JP6696782B2 - Beamforming method, measurement imaging device, and communication device - Google Patents

Description

  The present invention relates to a beamforming method that performs beamforming using arbitrary waves coming from a measurement target. Furthermore, the invention relates to a metrology imaging device and a communication device using such a beamforming method.

  In particular, the present invention is based on an arbitrary wave such as an electromagnetic wave, light, mechanical vibration, sound wave, or heat wave that comes from a measurement target, images the measurement target, or temperature or displacement in the measurement target. The present invention relates to a digital beam forming method in an imaging apparatus for nondestructively measuring a physical quantity, a composition, a structure, or the like. There are various objects to be measured, such as organic substances, inorganic substances, solids, liquids, gases, objects according to rheology, living things, astronomical objects, the earth, the environment, etc., and the application range is extremely wide.

  INDUSTRIAL APPLICABILITY The present invention is applied to non-destructive inspection, diagnosis, resource exploration, generation and manufacturing of materials and structures, monitoring of various physical or chemical repairs and treatments, application of revealed functions and physical properties, etc. Relevantly, in those cases, accuracy may be required under conditions such as non-invasive, minimally invasive, non-invasive that do not cause a large disturbance to the measurement target. Ideally, the object to be measured should be observed in situ, in situ.

  Further, the measurement object may be treated or repaired by the action of the wave itself, and the situation may be observed by performing beamforming on the response from the measurement object at that time. In addition, beamforming is performed in satellite communication, radar, sonar, etc. to realize an energy-saving, information-safe environment, and accurate communication is performed. Beamforming has also been applied to ad-hoc communication devices and mobile communications. When the measurement target is dynamic, real-time property is required, and beamforming is required to be completed in a short time.

  In the case of waves such as electromagnetic waves, light, mechanical vibrations, sound waves, or heat waves, the behavior as waves differs depending on the frequency, bandwidth, intensity, or mode. Many kinds of wave transducers have been developed so far, and imaging using a transmitted wave, a reflected wave, a refracted wave, a scattered wave (a forward scattered wave, a back scattered wave, or the like) of those waves is performed.

  For example, it is well known that ultrasonic waves having a high frequency among sound waves are used in nondestructive inspection, medical treatment, and sonar. Also in the radar, electromagnetic waves having appropriate frequencies (radio waves, FM waves, microwaves, terahertz waves, infrared rays, visible light, ultraviolet rays, radiation such as X-rays, etc.) are used according to the measurement target. The same is true for other waves, and since each wave behaves differently depending on frequency, different names are used, and various sensing and communication are performed according to the measurement target, medium, and frequency band (if electromagnetic waves are used, , Polarization can also be used).

  In those applications, a beam forming process is often performed by mechanically scanning a measurement target with a transducer, using the same transducer a plurality of times, or using a plurality of transducers arranged in an array in advance. .. It is well known that aperture surface synthesis processing is performed when observing the earth, land, ocean, and weather with satellite or airplane radar. In many cases, beamforming has a purpose to provide appropriate directivity and obtain high spatial resolution and high contrast in a region of interest or a point of interest, particularly when imaging a measurement target.

  As a result, by observing the waves generated from the measurement target, we observe reflections and transmissions caused by spatial changes in impedance, various types of scattering (Rayleigh scattering, Mie scattering, etc.), attenuation, or their frequency dispersion. It is possible to observe the structure and composition of the inside and the surface of the measurement target, as well as what the measurement target is. The measurement target may be observed with various spatial resolutions. Characterization can be done at the structure or composition level (eg, individual level, molecular level, atomic level, nuclear level, etc.).

  For the purpose of high-accuracy and high-resolution imaging, a signal compression technique has been used for a long time, and a typical one is a chirp wave technique or a coding compression technique. In some cases, such as ISAR (inverse synthetic aperture radar), the observed wave is subjected to inversion of the beam characteristics to perform super-resolution, but this is not always the case during aperture surface synthesis. ), There is also a case where the resolution is positively reduced. Among them, singular value decomposition, regularization, Wiener filter, etc. are effective.

  In addition, the encoding technique is also used in the case of separating a plurality of signals, for example, in the case of separating a received signal into a received signal corresponding to a transmitted signal having a different transmission position. It may separate waves coming from different directions, and may also identify and separate sources. In such a case, there is a great deal of reliance on a matched filter having high signal detection capability. However, while the signal energy can be obtained, when the movement of the measurement target accompanied by the deformation, the displacement, the strain, and the like are obtained, the spatial resolution becomes low, and the measurement accuracy thereof decreases. In separating waves and signals, it is also useful to use frequencies, bands, or multidimensional spectra.

  In imaging using the above-mentioned waves, the distribution of amplitude data normally obtained through quadrature detection, envelope detection, or square detection is displayed as a gray image or color image in one-dimensional, two-dimensional, or three-dimensional display. It often becomes a morphological image. In addition, functional observation is also possible, for example, in Doppler measurement using those waves, raw coherent signals are processed (ultrasonic Doppler, radar Doppler, laser Doppler, etc.).

  In addition, for example, in the field of medical ultrasonic waves, there is also a useful technique capable of detecting a moving tissue although there is no information on the displacement direction, unlike power Doppler. When microwaves, terahertz waves, or far infrared rays are used, the temperature distribution of the measurement target can be observed. The measured physical quantities may be displayed by being superimposed on the morphological image. In the field of image measurement, it is well known that motion is observed using a signal made incoherent through detection (cross-correlation processing, optical flow, etc.). In medical ultrasound and sonar, imaging using physically generated harmonics, chords, and difference tones is also performed. In particular, when the measurement target is dynamic, real-time property is required for the beam forming process.

  Also, in satellite communication, radar, sonar, etc., beamforming is performed to realize an information-safe environment while saving energy, and accurate communication is performed. Beamforming has also been applied to ad-hoc communication devices and mobile communications. It is also effective for communication with a specific person, a specific signal source, or a specific position. In communication, information may be sent in waves from the sender to the receiver, and the purpose alone may be achieved, or the receiver may respond to the sender with the results of the communication, or It may respond to the request, but of course, this is not the only example of communication. Depending on the communication target or the observation target, real-time property is required when the information content is dynamic, and in that case, beamforming is required to be completed in a short time.

  Under such circumstances, the inventor of the present application is developing an ultrasonic imaging technique for differentially diagnosing a lesion such as a cancer lesion or sclerosis of human tissue. The inventor of the present application is performing high resolution and high efficiency of HIFU (High Intensity Focus Ultrasound) treatment together with high resolution of echo imaging and high precision measurement imaging of tissue displacement. Their imaging is also based on the reception of echoes during intense ultrasonic radiation. These imagings are based on performing high-speed and appropriate beamforming, and have previously reported high-speed and appropriate detection methods, tissue displacement measurement methods, shear wave propagation measurement methods, and the like.

  The medical ultrasonic diagnostic imaging apparatus has been digitalized for more than 20 years. In older times, a device that performs mechanical scanning using a single-aperture conversion element, and then electronic scanning using a plurality of conversion elements and an array-type device composed of them, and performs signal processing is an analog device. To digital devices. Actually, the classical aperture synthesis processing itself was digital beamforming from the time when it was used in the radars mounted on satellites and airplanes, but the received signal strength was weak. For that reason, it was rarely used in medical ultrasound.

  On the other hand, in recent years, the inventor of the present application invented a multidirectional aperture plane synthesis method and invented beamforming in multiple directions from received echo data for aperture plane synthesis. As a result, it is possible to obtain a steering (deflection) image signal in multiple directions at the same frame rate as that of a normal electronic scan, and by performing coherent addition of these signals, lateral modulation imaging (depth direction It has a carrier frequency in the transverse direction, which is orthogonal to this, and it has become possible to achieve higher spatial resolution compared to ordinary imaging. Furthermore, by using the multidimensional autocorrelation method also invented by the inventor of the present application, it is possible to measure the displacement vector distribution in real time. In addition, in the case of incoherent addition, it is possible to reduce the speckle (usually, the transmission beam is generated in different directions to reduce the speckle, but according to the multidirectional aperture plane synthesis method, , High frame rates can be achieved). In addition to the field of ultrasonic waves, digitization is progressing in sensing devices that use microwaves, terahertz waves, radiation such as X-rays, other electromagnetic waves, vibration waves including sound, and waves such as heat waves for nondestructive inspection. Has been.

  For example, aperture surface synthesis in these sensing devices is active beamforming, and the waves to be processed are transmitted waves, reflected waves, refracted waves, or scattered waves (forward wave) of those waves generated by a transducer. Scattered waves or backscattered waves). On the other hand, in passive beamforming, for example, as in the case of observing temperature distribution based on the above microwave observation and observing the electrical activity source by the brain magnetic field of the living thing, self-divergence A transmission wave, a reflection wave, a refraction wave, or a scattered wave (a forward scattered wave, a back scattered wave, or the like) based on a wave emitted from a (self-emanating) signal source is targeted. There are many other examples that correspond to them, but as another example, recently, biological organisms are called photoacoustic, which is used as a measurement target. It has also been performed that a volume change is caused by a certain heat absorption, an ultrasonic wave is generated using this as a sound source, and peripheral blood vessels are identified as a result of beamforming.

  Digital devices require more processing time than analog devices, but their computing power has been significantly improved, and they have been downsized, are cheaper including data storage media, and have higher-order computations. There are many advantages such as easy application and high degree of freedom. In fact, even in the case of a digital device, particularly in a sensing device, high-speed analog processing after a signal is received by a sensor is extremely important, and AD conversion (Analogue-to-Digital conversion) is relatively close. It is properly realized in combination with the digital processing after being performed.

  In an analog device, transmission and reception beamforming are performed by analog processing. On the other hand, in the digital apparatus, transmission beamforming is performed by analog processing or digital processing, and reception beamforming is performed by digital processing. Therefore, in the present application, the digital beam former refers to one that performs reception beam forming by digital processing without fail.

  After receiving waves from a measurement target through a plurality of conversion elements, an array type device composed of them, or mechanical scanning of one or more conversion elements, so-called aperture plane synthesis processing, DAS (Delay and Summation: phasing) Processing is performed. In transmission, a plurality of elements may be driven to perform transmission beamforming, and classical aperture plane synthesis based on single element transmission may be performed. However, in reception beamforming, common , DAS processing is performed.

  That is, the transmission beamforming is performed by analog processing or digital processing. On the other hand, in receive beamforming, a wave is received by each element in the array or an element at a different position to generate a receive signal, and the analog receive signal is generated after level adjustment by analog amplification or attenuation and analog filtering. AD conversion is performed on the digital received signal, and the digital received signal is stored in the memory. After that, a device or computer equipped with general-purpose calculation processing power, PLD (Programmable Logic Device), FPGA (Field-Programmable Gate Array: rewritable gate array), DSP (Digital Signal Processor: Digital Signal Processor), A stored signal is digitally processed by using a GPU (Graphical Processing Unit), a microprocessor, a dedicated computer, a dedicated digital circuit, a dedicated device, or the like. It

  A device that performs these digital processes may include an analog device, an AD converter, a memory, or the like. In some cases, the computing device or computer has multi-core. As a result, at the time of reception, it becomes possible to easily carry out dynamic focusing, which is almost impossible with an analog device. Parallel processing is also performed. A transmission line (for example, a laminated circuit or the like) or a wideband wireless path is important in accelerating analog processing and digital processing.

  The dynamic focusing improves the spatial resolution of the generated image signal in the range direction and the depth direction (depth direction) of the measurement target. On the other hand, transmission dynamic focusing is possible only in classical aperture plane synthesis by single element transmission. In order to secure the energy of the transmission wave, transmission beamforming at a fixed focus position by driving a plurality of elements is often performed instead of aperture plane synthesis by single element transmission.

  The inventor of the present application has invented high frame rate echo imaging in which a wave such as a plane wave having a wide wavefront in the lateral direction is transmitted and a wide range of areas is interrogate in one transmission. Further, the inventor of the present application performs coherent addition (superposition) of a plurality of waves of this type having different steering (deflection) angles to perform lateral modulation and lateral band broadening (horizontal lateral high resolution). In particular, when the above-mentioned multidimensional autocorrelation method is realized, blood flow in the carotid artery with shear wave propagation and fast blood flow, or blood flow in the heart chamber with complicated flow, etc. Was invented to measure as a multidimensional displacement vector. The same applies when multi-directional aperture plane synthesis is performed and when transmission beam forming is performed. In addition, a wave having a plurality of different carrier frequencies may be generated and superposed on each other to realize a wide band in the axial direction (higher resolution in the axial direction).

  Such a process is performed in the case of active beamforming, but the transmitter is not used in passive beamforming. Thus, a digital beamformer usually consists of a transmitter (in the case of active beamforming), a receiver, and a DAS processing device, and is realized by assembling those devices. A small package is now available at low cost.

  This DAS processing is performed by interpolating approximation processing in the spatial domain to delay the received signal at high speed for phasing, and by phase rotation processing that takes a huge amount of time but multiplies the complex exponential function in the frequency domain. There is one that applies a delay with high accuracy based on the Nyquist theorem (a past invention of the inventor of the present application), and adds received signals in the spatial domain after phasing (phasing addition). In a digital device, a command signal generated by a control unit may be used as a trigger signal for digital sampling (AD conversion) of an analog reception signal, for example, for a transmitter to generate a transmission signal to a driving element. ..

  In addition, when a plurality of elements are driven by transmission delay in one beamforming, an analog or digital transmission delay that is mounted in advance in the transmission unit and realizes a transmission focus position, steering direction, etc. that can be selected by the operator. May use patterns. Further, in the reception digital processing, the command signal for the element to be driven first, the command signal for the element to be driven last, or the command signal for driving another element is used as the trigger signal, and There is a case where sampling is started for the signal of and the digital delay is applied. These command signals may be generated based on command signals for starting beamforming for one frame.

  If a digital delay is performed in the transmission delay, an error determined by the clock frequency for generating the digital control signal is inevitably generated unlike the analog delay. Therefore, the transmission delay is preferably the analog delay. Further, if a digital delay is applied in the reception to realize the reception dynamic focusing, an error occurs due to the above-mentioned interpolation approximation processing. Therefore, it is necessary to increase the sampling frequency of the AD converter at a high cost or to increase the above-mentioned high frequency. There was no choice but to perform low-speed beamforming by applying an accurate digital delay (phase rotation processing).

  In the former case involving interpolation approximation processing, phasing addition may simply add echo signals from a position including the coordinate position of the generated signal value, or bi-linear or multi-dimensional polynomial The accuracy may be improved by interpolation using, for example. The former is significantly faster but less accurate than the latter, which uses complex exponentials. The latter is highly accurate but extremely slow. This phasing addition is performed under the assumption that the wave propagation velocity is known, or is assumed to be constant in the region of interest in many cases. On the other hand, it is also performed to measure the propagation velocity and correct the phase aberration. For example, before or after beam forming, the phase is evaluated by evaluating a cross-correlation function between adjacent beam signals or beam signals at different angles. Aberration can be obtained (if the propagation velocity is uniform, then interference analysis is performed).

  Compared with the case where the aperture elements are distributed or arrayed in a one-dimensional space, the aperture elements are distributed two-dimensionally or three-dimensionally, or the aperture elements form a two-dimensional or three-dimensional array. In this case, it is necessary to perform more processing for beamforming, and many processors are mounted to perform parallel processing. Beam forming at a distant position with less interference, transmission beam forming in a plurality of directions with different steering angles, and single transmission beam forming may be processed in parallel.

  In terms of communication control, it is necessary for waves to be generated appropriately, reflecting the type and amount of communication data, or the characteristics of the medium, and optimized under these observations. Communication is desirable. Separation of interfering waves is also performed using analog devices or by analog or digital signal processing. Controlled waves of propagation direction, coding, frequency and / or bandwidth are important.

  As another invention of the inventor of the present application, which is similar to the above-described multidirectional aperture plane synthesis processing, it is possible to perform multidirectional receive beamforming for one transmit beamforming to improve the frame rate. Also, apodization may be important in beamforming. For example, each of transmission and reception apodization may be performed in order to reduce side lobes, which has a trade-off with lateral resolution and should be performed appropriately. On the other hand, with emphasis on spatial resolution, a simple beam former that does not perform apodization is often used. However, the inventor of the present application has reported that appropriate apodization is necessary to obtain lateral resolution while suppressing side lobes during steering. In addition, some of the past inventions of the inventor of the present application remove side lobes in the frequency domain.

  In addition, contrast agents (for example, microbubbles in medical ultrasonic imaging) may be used to apply the nonlinear characteristics of waves in a target, and the inventor of the present application is actively involved in applying these. It is possible to irradiate waves with high intensity or waves containing harmonics (broadband transmission) and to perform nonlinear processing on received coherent signals or coherent signals after phasing and addition, and high spatial resolution and side Invented high contrast imaging by suppressing lobes. The inventor of the present application also invented a highly accurate tissue displacement (vector) measurement based on the non-linear processing.

  It is also possible to generate an imaging signal using a virtual source. As for the virtual source, it has been reported in the past that the virtual source is installed in front of the physical aperture and the virtual source is installed at the transmission focus position. Further, the inventor of the present application has set up not only a virtual source but also a detector at an arbitrary position without using a focus, and a physical source or detector of a wave may be an arbitrary scatterer or diffraction grating. It reports that it can be installed in the position. It is possible to realize high resolution spatial resolution and widen the field of vision (FOV).

  As the imaging form, quadrature detection, envelope detection, or square detection is used, but the inventor of the present application is also actively displaying the corrugation itself as a color image or a gray image, and the phase information We emphasize display including. As described above, development of multidimensional devices using various waves is being promoted for various purposes.

  There are several digital beamformings using the fast Fourier transform disclosed so far, and one of them is an analog processing (Fourier transform) which is an analytical solution of classical monostatic aperture synthesis. Non-Patent Document 1) is digitized, and exactly the classical aperture plane synthesis is performed at high speed and high accuracy through Fast Fourier Transform (see Non-Patent Document 2). In this processing, interpolation approximation is not required, but in the case of steering (deflection) or multi-static type aperture plane synthesis (generally, reception by using one element or a plurality of peripheral elements in transmission). Digital processing is not disclosed.

  All of the other digital beam forming methods disclosed require an interpolation approximation process and have low accuracy. For example, there is disclosed a method of performing wave number matching through fast Fourier transform including steering in plane wave transmission (see Non-Patent Document 3-5), but in that case and the array shape of the array is not flat. In cases where calculation and image display are performed (when the array aperture is a circular arc (see Non-Patent Document 6)), interpolation approximation processing is required and accuracy is low. The method using the fast Fourier transform at the time of transmitting a plane wave is also disclosed in Patent Documents 1-4, but all of them perform wave number matching through interpolation approximation. By performing wave number matching by the interpolation approximation, the wave number vector coordinate system of the angular spectrum is set at equal intervals to obtain a multidimensional spectrum, and fast inverse Fourier transform is performed, whereby the beam forming can be completed at high speed.

  Recently, Non-Patent Document 5 discloses performing Fourier transform on wave number matching for non-equidistant sampling signals, but again, this is also based on interpolation approximation processing. As mentioned above, digital beamforming has a long history, but when the real time (computation speed) before displaying an image is the most important, interpolation approximation is often performed and it provides the best accuracy. It does not mean that In addition, regarding the most popular (fixed) fixed focus processing known to perform the DAS processing and the steering at that time, the processing method performed through the digital fast Fourier transform is not disclosed.

  Further, although there is a report on the migration method (for example, refer to Non-Patent Document 7), this also requires interpolation approximation in wave number matching. In order to obtain accuracy in the processing involving these interpolation approximations, it is usually necessary to increase the sampling frequency of the AD converter and oversample sufficiently.

US Pat. No. 5,720,708 US Pat. No. 6,685,641 US Pat. No. 7,957,609 U.S. Patent Application Publication No. 2009/0036772 U.S. Pat. No. 8,211,019 US Pat. No. 7,775,980 US Patent Application Publication No. 2011/0172538

J. W. Goodman, "Introduction to Fourier Optics" 2nd ed., McGraw-Hill Co, Inc., 1996 L. J. Busse, IEEE Trans. UFFC, vol. 39, no. 2, pp. 174-179, 1992 J. Cheng, J.-y. Lu, IEEE Trans UFFC, vol. 53, no. 5, pp. 880-899, 2006 H. Peng, J.-y. Lu, X. Han, Ultrasonics, 44, e97-e99, 2006 P. Kruizinga et al, IEEE Trans. UFFC, vol. 59, no. 12, pp. 2684-2691, 2012 M. A. Haun, D. L. Jones, W. D. O'Brien, Jr., IEEE Trans. UFFC, vol. 49, pp. 861-870, 2002 C. Sumi, IEEE Trans. UFFC, vol. 55, pp. 2607-2625, 2008 C. Sumi, S. Uga, "Effective ultrasonic virtual sources which can be positioned independently of physical aperture focus positions," Rep. Med. Imag., Vol. 3, pp. 45-59, 2010 M. Soumekh, "Fourier array imaging," PTR Prentice-Hall, Englewood Cliffs, New Jersey 07632, 1994 S. Haykin, A. Steinhardt ed. "Adaptive rader detection and estimation," John Wiley & Sons, inc. New York. 1992 K.W.Hollman, K.W.Rigby, M.O'Donnell, "Coherence Factor of Speckle from a Multi-Row Probe," Proc. Of IEEE Ultrasonics Symp, pp. 1257-1260, 1999. D. Garcia, L. L. Tarnec, S. Muth, E. Montagnon, J. Poree, G. Cloutier, IEEE Trans. UFFC, vol. 60, no. 9, pp. 1853-1867, 2013 C. Sumi, IEEE Trans. UFFC, vol. 55, pp. 24-43, 2008 C. Sumi, Y. Ishii, Rep. Med. Imag., Vol. 5, pp. 57-101, 2012 C. Sumi, IEEE Trans. UFFC, vol. 46, pp. 158-166, 1999 S. Srinivasan, F. Kallel, and J. Ophir, Ultrasound Med. Biol., Vol. 28, pp. 359-368, 2002 C. Sumi, IEEE Trans. UFFC, vol. 55, pp. 297-307, 2008 C. Sumi and K. Sato, IEEE Trans. UFFC, vol. 55, pp. 787-799, 2008 C. Sumi, Y. Takanashi, K. Ichimaru, Rep. Med. Imag., Vol. 5, pp. 23-50, 2012 J. A. Jensen, "Field: A program for simulating ultrasound systems," Med, Biol, Eng, Comp, 10th Nordic-Baltic Conference on Biomedical Imaging, Vol. 34, Supplement 1, Part 1: pp. 351-353, 1996 B. Schrope, V. L. Newhouse, V. Uhlendorf, "Simulated capillary blood flow measurement using a nonlinear ultrasonic contrast agent," Ultrason. Imag., Vol. 14, pp. 134-158, 1992 P. N. Burns, S. R. Wilson, D. H. Simpson, "Pulse Inversion Imaging of Liver Blood Flow: Improved Method for Characterizing Focal Masses with microbubble Contrast," Investigative Radiology, vol. 35, no. 1, pp. 58-71, 2000 M. A. Averkiou, D. N. Roundhill, J. E. Powers, "A new imaging technique based on the nonlinear properties of tissues," 1997 IEEE Ultrasonics symp, pp. 1561-1566, 1997 B. Haider, R. Y. Chiao, "Higher order nonlinear ultrasonic imaging," 1999 IEEE Ultrasonics symp., Pp. 1527-1531, 1999 A. Needles, M. Arditi, NG Rognin, J. Mehi, T. Coulthard, C. Bilan-Tracey, E. Gaud, P. Frinking, D. Hirson, FS Foster, "Nonlinear contrast imaging with an array-based micro -ultrasound system, "Ultrasound Med. Biol., vol. 36, no. 12, pp. 2097-2106, 2010 J. R. Doherty, G. E. Trahey, K. R. Nightingale, M. L. Palmeri, "Acoustic Radiation Force Elasticity Imaging in Diagnostic Ultrasound," IEEE Trans. On UFFC, vol. 60, no. 4, pp. 685-701, April 2013 K. Hynynen, "Demonstration of enhanced temperature elevation due to nonlinear propagation of focused ultrasound in dog's thigh in vivo," Ultrasound Med. Biol. Vol. 13, no. 2, pp. 85-91, 1987. Y. Huang, NI Vykhodtseva, K. Hynynen, "Creating brain lesions with low-intensity focused ultrasound with mcrobubbles: A rat study at half a megahertz," Ultrasound Med. Biol., Vol. 39, no. 8, pp. 1420 -1428, 2013 C. Sumi, "Utilization of an ultrasound beam steering angle for measurements of tissue displacement vector and lateral displacement," Reports in Medical Imaging, vol. 3, pp. 61-81, 2010

  As described above, if a digital delay is applied in the reception in order to realize the reception dynamic focusing, an error occurs due to the above-described interpolation approximation processing, so that the sampling frequency of the AD converter is increased sufficiently at a high cost. Or, the above-mentioned high-precision digital delay (phase rotation processing) must be applied to achieve low-speed beamforming.

  Up to now, the target waves are electromagnetic waves, vibration waves (mechanical waves) including sound waves (compression waves), shear waves, surface waves, etc., or waves such as heat waves. (Scattered or backscattered waves, etc.), refracted waves, surface waves, shock waves, or methods of digital beamforming for those waves originating from a self-emanating wave source are disclosed. As described above, it is limited to the monostatic type aperture plane synthesis that does not include steering, the plane wave transmission that includes steering, and the migration method. Further, except for the monostatic type aperture plane synthesis, digital beam forming could not be performed without the need for interpolation approximation. Therefore, its accuracy was low.

  On the other hand, when using a transmitting or receiving transducer array device having an arbitrary aperture shape (which may be used for both transmission and reception, or transmission and reception may be related to different waves), or a passive When only the receiving transducer is used in beam forming, no interpolation approximation is required even if the coordinate system of the transmit / receive beam and the coordinate system of the image display are different, regardless of the presence or absence of transmission or reception focusing or steering. Moreover, it is desired to perform arbitrary beamforming at high speed and with high accuracy.

  For active beamforming, transmit and receive transducer array devices with arbitrary aperture shapes (transducers may be used for both transmission and reception) are used. Also, in the case of passive beamforming, only receive transducer array devices with arbitrary aperture shapes are used. In these cases, it is desired to realize arbitrary beamforming at high speed and with high accuracy by digital processing. Virtually any focusing and any steering is desired to be performed with a transducer array device having an arbitrary aperture shape.

  After beamforming after phasing addition, linear or non-linear signal processing is applied to a plurality of beams having different wave parameters such as frequency in each direction, bandwidth, pulse shape, and beam shape. A beam having a new value for at least one of those wave parameters may be newly generated (frequency modulation, broadband, multi-focus, etc.), and focusing is performed in such beam forming. Steering (deflection) and apodization are performed using a transducer array device having an arbitrary aperture shape based on DAS processing.

  Since the propagation velocity of waves is determined by the physical properties of the medium under physical conditions, if the aperture element forms a two-dimensional or three-dimensional distribution or a multidimensional array for imaging in a multidimensional space, it is a one-dimensional case. Compared to the above, a large number of beamformings are performed, and the number of processing data used for one beamforming also increases, which requires a huge amount of time, but the high speed of beamforming is obtained, It is desired to use a device that processes these beamformings in so-called real time or a device that can display the results in a short time.

  Further, up to now, regarding digital beam forming through Fourier transform, what is performed through interpolation approximation in a Cartesian coordinate system mainly when using a one-dimensional or two-dimensional linear array transducer is disclosed. Even when the coordinate system at the time of reception and the coordinate system of the result (image) display are different, it is desired to perform digital beamforming without performing any interpolation approximation.

  The method disclosed regarding the case where the array aperture shape is not flat (for example, when the array aperture is a circular arc) also performs interpolation approximation. As a typical example, when a convex type transducer is used, or when electronic or mechanical sector scanning or IVUS (intravascular ultrasound) scanning is performed, transmission and reception are performed in an arbitrary coordinate system such as a polar coordinate system. It is desired to process the digital signal obtained from the wave motion and obtain the beam-formed signal directly in an arbitrary image display system (arbitrary coordinate system) such as a Cartesian coordinate system without performing interpolation approximation.

  In recent years, memories and AD converters have become very inexpensive, but by sampling the waves based on the Nyquist theorem without oversampling, it is possible to perform time-consuming DAS processing when interpolation approximation is not performed. It is desired that the corresponding beamforming can be performed at high speed. Proper apodization can also be important.

  As a result of solving these problems, the spatial resolution and contrast (including the effect of suppressing side lobes) of the image signal obtained in real time or in a short time are high, and the movement of the target (displacement) is obtained from the obtained signal. ), Deformation, or measurement of temperature or the like, it is desired to realize highly accurate measurement. For example, in the field of medical ultrasonic waves, in recent years, Doppler method is applied to echo signals to measure tissue displacement and speed, and then spatiotemporal differentiation is applied to this to obtain acceleration, strain, etc. to form an image. became. Spatial-temporal differentiation is a process that amplifies a high-frequency measurement error and deteriorates the SN ratio (Signal-to-Noise Ratio). Therefore, it is necessary to realize a highly accurate displacement measurement using a phase. The high-precision beamforming that achieves this is dynamic focusing based on so-called DAS processing. A three-dimensional imaging device using a two-dimensional array or a three-dimensional array also tends to become popular. As described above, it is desired to achieve arbitrary beam forming including dynamic focusing at high speed and with high accuracy without performing interpolation approximation.

  Recently, the inventor of the present application has proposed a highly accurate measurement method for relatively fast moving tissue displacement and shear wave propagation based on high-speed beamforming (high-speed transmission / reception in a region of interest) by polarized plane wave transmission. Although realized, it is desired to perform beamforming at high speed and with high accuracy without requiring interpolation approximation even when such focusing is not performed. By performing high-speed beam forming while changing the steering angle and performing coherent addition, it is also possible to obtain almost the same high image quality (spatial resolution and contrast) at high speed as compared with scanning using a normal focusing beam. .. High-speed beamforming is also effective for multidimensional imaging using a multidimensional array.

  In addition, steering and multi-static type aperture plane synthesis in the classical aperture plane synthesis (monostatic type) based on scanning by driving one element at a time, which has not been disclosed so far, can be performed at high speed without requiring interpolation approximation. It is desirable to implement it with high accuracy. Further, even when so-called migration processing is used, it is desired to perform arbitrary beamforming at high speed and with high accuracy without performing interpolation approximation in an arbitrary coordinate system. Other specific examples of beamforming that are desired to be realized are as described in other portions of the present specification, and it is desirable that those beamforming can be similarly performed at high speed and with high accuracy. Be done.

  Therefore, a first object of the present invention is to use a digital beam former having a digital operation function and perform arbitrary beam forming at high speed and with high accuracy without performing approximate calculation. This enables various applications of the wave motion described below, including super-resolution using non-linear processing.

The present invention has been made to solve at least part of the above problems. A beamforming method according to a first aspect of the present invention, in an orthogonal coordinate system defined by a receiving aperture element array, when an arbitrary wave is transmitted from a wave source located in an arbitrary direction toward a measurement target, the measurement is performed. A beamforming method used in a measurement imaging apparatus for generating an image signal of an object, the method comprising: receiving a wave coming from the object to be measured by at least one receiving aperture element and generating a received signal; By performing at least Fourier transform and wave number matching on the reception signal generated in step (a), a zero-degree or non-zero degree deviation angle or elevation angle or azimuth angle with respect to the front direction of the reception aperture element. There line beamforming processing of the transmission component or reception component includes performing a transmission content or receive content steering makes the steering angle that is desired to be the first direction and the second direction or the third coordinate axis direction Step (b) of generating an image signal in the Cartesian coordinate system of step (b), wherein step (b) is applied to an angular spectrum in a wave number domain or a frequency domain obtained by performing a multidimensional Fourier transform on the received signal. In order to perform wave number matching without directly performing interpolation approximation processing, (b1) Fourier transform in the first direction with respect to the received signal when the deviation angle or elevation angle of the steering angle is zero degrees. And performing a Fourier transform in the second direction or the third direction, and then multiplying by a complex exponential function having an exponent part including the spatial coordinates in the first direction and the wave number or carrier frequency of the wave. By shifting the angular spectrum in a wave number space or a frequency space, (b2) in the first direction with respect to the received signal when the steering angle deviation or elevation angle is non-zero. After performing the Fourier transform, it is multiplied by a complex exponential function having an exponential part including the spatial coordinates in the second direction or the third direction and the wave number or carrier frequency of the wave, and the second direction or the third In the wavenumber space or frequency space by multiplying by a complex exponential function having an exponential part containing the spatial coordinates in the first direction and the wavenumber or carrier frequency of the wave after performing a Fourier transform in the direction Including shifting .
A measurement imaging apparatus according to a second aspect of the present invention provides the measurement when an arbitrary wave is transmitted from a wave source located in an arbitrary direction to a measurement target in a rectangular coordinate system defined by a receiving aperture element array. A measurement imaging apparatus for generating an image signal of an object, comprising: at least one reception aperture element for receiving a wave coming from the measurement object to generate a reception signal; and a reception signal generated by the reception aperture element. On the other hand, by performing at least Fourier transform and wave number matching, a transmission component or a reception component that forms a steering angle represented by a declination angle or elevation angle or azimuth angle of zero degree or non-zero degree with the front direction of the reception aperture element. There line beamforming processing of the transmission component or reception component comprises performing a steering, the first direction and the second direction or the third signal to generate an image signal in a desired orthogonal coordinate system with the direction of the coordinate axis of the A signal processing unit, wherein the signal processing unit performs wave number without directly performing interpolation approximation processing on an angular spectrum in a wave number domain or a frequency domain obtained by performing a multidimensional Fourier transform on the received signal. In order to perform matching, when the declination or elevation of the steering angle is zero degrees, the received signal is subjected to Fourier transform in the first direction, and then in the second direction or the third direction. After applying a Fourier transform, the angular spectrum is shifted in wavenumber space or frequency space by multiplying by a complex exponential function having an exponential part containing the spatial coordinates in the first direction and the wavenumber or carrier frequency of the wave. When the declination or elevation of the steering angle is non-zero, after performing Fourier transform on the received signal in the first direction, the spatial coordinates of the second direction or the third direction And a wavenumber or carrier frequency of the wave, and a complex exponential function having an exponential part, and Fourier transform is performed in the second direction or the third direction. Then, the spatial coordinates of the first direction and the wave The angular spectrum is shifted in wavenumber space or frequency space by multiplying by a complex exponential function having an exponential part containing the wavenumber or carrier frequency .
A beamforming method according to a third aspect of the present invention is directed to an arbitrary direction in a Cartesian Cartesian coordinate system that uses coordinates in an axial direction y defined by the orientation of an aperture of a flat receiving aperture element array and a lateral direction x orthogonal thereto. Arbitrary waves are transmitted from the located wave source toward the measurement target, and the waves coming from the measurement target are transmitted or received in the direction in which the deflection angle (deflection angle) θ that forms the axial direction is zero degrees or non-zero degrees. In the case where the same wave coming from the measurement target is further subjected to dynamic reception focusing in the direction in which the deflection angle (declination angle) φ formed with the axial direction is zero degree or non-zero degree, the measurement target is measured. (A) receiving a wave arriving from the device by at least one receiving aperture element to generate a received signal, and performing at least Fourier transform and wave number matching on the received signal generated in step (a) And (b) performing a beam forming process according to the step (b), wherein the step (b) does not perform wave number matching including interpolation approximation processing in the wave number domain or the frequency domain on the received signal, The wave number k ₀ (= ω ₀ / c) represented by using the wave number k of the wave and the carrier frequency ω _{0 of the} wave in the Fourier transform with respect to y, and the complex exponential function represented by the imaginary unit i (101) The wave number matching in the lateral direction x is performed by multiplying by
Further, the product is Fourier-transformed in the horizontal direction x so as to have a resolution in the axial direction y, and a complex exponential function (which can be implemented by removing the effect of wave number matching performed in the horizontal direction x on the obtained calculation result ( 102) and at the same time, by performing a complex exponential function (103), the wave number matching in the axial direction is performed, where the wave number in the lateral direction is represented by k _x ,
This includes directly generating an image signal in a Cartesian coordinate system by performing wave number matching without performing interpolation approximation processing.

  The present invention is based on performing fast Fourier transform or multiplication of complex exponential function, and Jacobi operation appropriately, without performing approximation calculation required when performing normal digital processing, An apparatus and a method for performing arbitrary beam forming in an arbitrary orthogonal coordinate system at high speed and with high accuracy are included. In order to solve the problem, the reflected wave, the transmitted wave, and the scattered wave are targeted for the waves such as electromagnetic waves, vibration waves (mechanical waves) including sound waves (compression waves), shear waves, surface waves, etc., or heat waves. Waves (forward scattered wave or back scattered wave, etc.), refraction waves, surface waves, shock waves, those waves generated from self-emanating wave sources, waves emitted from moving bodies, or unknown wave sources An appropriately set digital signal processing algorithm (in the implemented digital circuit or software) and analog or digital hardware is used for the observed waves such as those coming from.

  The hardware configuration may include a device equipped with a phasing addition device of a normal digital beam former of each wave device, and further include a device having an arithmetic function for performing digital wave signal processing. The software may be installed, or a digital circuit for realizing the calculation may be configured and used. As other necessary devices, at least a normally used transducer, transmitter, receiver, storage device for received signals, and the like may be provided, which will be described in detail later. Harmonic waves are also processed. Beamforming using virtual sources and receivers is also performed. Parallel processing is also performed to generate multiple beams at the same time.

  Further, in the present invention, in order to realize high-speed and high-precision processing, in addition to analog devices such as level adjustment by analog amplification or attenuation and analog filtering described above, analog signal processing devices (driving signal waveform Effective application of linear elements and especially non-linear elements for changing waveforms such as emphasizing and attenuating features, and devices, computers, PLDs (Programmable Logic Device) equipped with general-purpose computational processing capacity as described above. ), An FPGA (Field-Programmable Gate Array), a DSP (Digital Signal Processor), a GPU (Graphical Processing Unit), a microprocessor, or the like may be used, but a dedicated computer or a dedicated digital circuit, or The stored signal may be digitally processed using a dedicated device.

  It is important that those analog devices, AD converters, memories, and devices that perform digital signal processing (multicore, etc.) have high performance, but the number of communications between devices, communication line capacity, wiring, or Broadband wireless communication is also important. Particularly, in the present invention, in addition to the case where the functional devices are properly mounted on one chip or the substrate (when they are removable), the functional devices are directly mounted on the one chip or the substrate. (Including lamination) is desirable. Parallel processing is also important. When the device is non-detachable, when the computer also serves as the control unit, it is possible to obtain a significantly higher security performance than the security obtained under normal program control. On the other hand, current legislation will increasingly require disclosure of processing details.

  According to one aspect of the present invention, a digital beamformer having a digital operation function is used, and arbitrary beamforming can be performed at high speed and high accuracy through fast Fourier transform without performing approximate calculation. It will be possible. As will be described in detail later, the present invention is based on the proper use of multiplication of complex exponential functions and Jacobi operation, and enables high-speed arbitrary beamforming in arbitrary Cartesian coordinate systems including curved coordinate systems. In addition, it is realized with high accuracy without interpolation approximation.

  Although any beam forming including conventional beam forming can be realized by using DAS (Delay and Summation) processing, according to the present invention, when a physical aperture constitutes a one-dimensional array, a general-purpose PC (personal computer) is used. ), The calculation speed is significantly faster than 100 times faster. When the aperture elements form a two-dimensional or three-dimensional distribution or a multi-dimensional array, the problem that a lot of processing time is required can be more effectively solved, and the high speed of beamforming becomes more effective.

  That is, according to the present invention, a transmission or reception transducer array device (which may be used for both transmission and reception) or a sensor array device having an arbitrary aperture shape is used, and any beamforming is approximated at high speed. It can be realized by digital processing with high accuracy without performing. Substantially any focusing and any steering (deflection), any apodization can be performed with an array device having any aperture shape.

  For example, in the field of medical ultrasound images, in addition to a Cartesian coordinate system using a linear transducer, in a convex type, a sector scan, or IVUS (intravascular ultrasound), physical transmission, reception, and digitization are performed using a polar coordinate system. What is done is popular and is used properly according to the observation target. For example, when observing the dynamics of the heart through the sternum gap, a sector scan is usually performed. Further, in the case of an array type opening shape or a transducer based on PVDF (polyvinylidene fluoride), the opening may be deformable in some cases. That is, according to the present invention, a digital signal obtained from a wave transmitted and received in an arbitrary coordinate system is processed, and a beam-formed signal is directly obtained in an arbitrary coordinate system such as an image display system without performing interpolation approximation. be able to.

  In multi-static aperture plane synthesis, echo data frames composed of echo signals received at the same position among multiple reception positions with respect to the transmission position are generated by the number of reception elements, and each echo in the frequency domain is generated. The data frame is subjected to monostatic aperture plane synthesis processing according to the present invention, and the result of these processings superimposed is subjected to inverse Fourier transform. As a result, since echo data can be generated by the same number of aperture plane combining processes as the number of channels of the receiving aperture, a low spatial resolution image signal is generated by the DAS known as a multi-static type processing method and superposed to obtain high spatial resolution. It is faster than the method of generating an image signal.

  Further, based on the multi-static processing according to the present invention, dynamic reception and steering at the time of general transmission fixed focus can be performed at high speed and with high accuracy. Either can be achieved by performing the appropriate phase rotation process using complex exponential multiplication.

  Further, regarding the coordinate system, the present invention is based on performing Jacobi operation in the Fourier transform, for example, in the signal processing of convex or sector scan, or IVUS, to echo data transmitted and received in the polar coordinate system. Based on this, the echo data can be directly generated in the Cartesian coordinate system of the display system with high accuracy and high speed without interpolation approximation.

  According to the present invention, even if so-called migration processing is used, arbitrary beamforming can be processed at high speed and with high accuracy without performing interpolation approximation in an arbitrary coordinate system. Further, according to the present invention, high SN ratio and high resolution imaging using a virtual source can be performed at high speed. Further, according to the present invention, the frequency modulation and widening of the beam performed under linear processing or non-linear processing, multi-focus, parallel processing, virtual sources and virtual receivers, etc. can be performed at high speed with high accuracy under digital processing. Can be realized. The present invention is also useful in beamforming optimization that requires a large amount of calculation.

  As described above, according to the present invention, electromagnetic waves, vibration waves (mechanical waves) including sound waves (compression waves), shear waves, shock waves, surface waves, etc., or waves such as heat waves are targeted, Arbitrary beamforming even when the coordinate system of transmission and reception is different from the coordinate system of generating a beamformed signal, regardless of the focusing of transmission or reception, steering of transmission or reception, and the presence or absence of apodization of transmission or reception. Can be performed with high accuracy and high speed without performing interpolation approximation based on digital processing.

  This not only improves the frame rate when displaying an image of the beamformed signal, but also provides high spatial resolution and high contrast in terms of image quality. Furthermore, the beamformed signal is used for displacement and deformation. Or, if the temperature or the like is measured, the measurement accuracy is also improved. The high-speed processing has a great effect in multidimensional imaging using a multidimensional array. The present invention relates to a mathematical algorithm related to wave propagation, and is the result itself of deriving a solution that does not include approximation calculation through digital calculation, but is not easily conceivable.

The typical block diagram which shows the structural example of the measurement imaging apparatus or communication apparatus which concerns on the 1st Embodiment of this invention. FIG. 2 is a representative block diagram showing in detail a configuration example of the apparatus main body shown in FIG. 1. The schematic diagram which shows the example of arrangement | positioning of the some transmission aperture element in a transmission transducer. FIG. 3 is a block diagram showing a configuration of a receiving unit or a receiving device equipped with a phasing adder and its peripheral devices. The schematic diagram of transmission of a polarized plane wave. The flowchart which shows the digital signal processing at the time of polarization plane wave transmission. The schematic diagram in the case of transmitting a wide wave in the radius r direction in the angle θ direction in polar coordinates (r, θ) (cylindrical wave transmission). Schematic diagram when a wide wave is transmitted in the radius r direction in the angle θ direction of the polar coordinate system (r, θ) using a virtual source installed behind a physical aperture of an arbitrary aperture shape (cylindrical wave transmission) .. The schematic diagram at the time of generating another opening or a wave in the position of the physical opening of arbitrary opening shape, or its back or front. Schematic diagram of monostatic aperture plane composition. The schematic diagram of a spectrum generated by steering in monostatic type aperture plane synthesis (θ is a steering angle). Schematic diagram of multi-static type aperture plane synthesis. Schematic diagram of fixed focusing using a linear array. The flowchart which shows the digital signal processing at the time of cylindrical wave transmission. Schematic diagram of fixed focusing using a convex array. 6 is a flowchart showing a migration process when a polarized plane wave is transmitted. The figure which shows the numerical phantom used in the simulation. The figure which shows the sound pressure waveform of the transmission pulse used in the simulation. The figure which shows the image obtained using the method (1) in polarization plane wave transmission. The figure which shows the image obtained using the method (1) in polarization plane wave transmission. The figure which shows the deflection angle and error which were obtained using method (1) in polarization plane wave transmission with respect to a set angle. The figure which shows the error of the deflection angle obtained using the method (1) in polarization plane wave transmission. The figure which shows the image acquired using the method (1) with the compound method in polarization plane wave transmission. The figure which shows the point spread function implement | achieved using the method (1) in polarization plane wave transmission. The figure which shows the image obtained using the migration method of method (6) in polarization plane wave transmission. The figure which shows the image obtained by the monostatic type aperture plane synthesis | combination of method (2). The figure which shows the image obtained by the multi-static type aperture plane synthesis | combination of method (3). The figure which shows the point spread function implement | achieved by the multi-static type aperture plane synthesis | combination of method (3). The figure which shows the image obtained by the fixed focusing transmission of the method (4). The image obtained by the method (5-1) in the cylindrical wave transmission using the convex array and the image obtained by the method (5-1 ') in the cylindrical wave transmission using the linear array are shown. Fig. The figure which shows the image obtained by fixed focusing transmission of a convex type array and the method (5-2). The block diagram which shows the structural example of the imaging device which concerns on the 3rd Embodiment of this invention. The block diagram which shows the structural example of the imaging device which concerns on the 4th Embodiment of this invention and its modification. The schematic diagram which shows the example of arrangement | positioning of a some transducer. The figure for demonstrating the form of a wave when using a one-dimensional transducer array. The figure which shows the angle of the beam direction in the space domain and frequency domain in the case of two-dimensional measurement, and the angle of arrival of a wave, and the gravity center of a spectrum. The figure which shows two deflection beams used for a lateral direction modulation method in a two-dimensional space. FIG. 6 is a diagram showing changes in the spectrum of an echo signal according to an embodiment of the present invention. FIG. 6 is a diagram showing changes in an autocorrelation function of an echo signal according to an embodiment of the present invention. FIG. 6 is a diagram showing changes in an autocorrelation function of an echo signal according to an embodiment of the present invention. FIG. 6 is a diagram showing changes in an autocorrelation function of an echo signal according to an embodiment of the present invention. FIG. 6 is a diagram showing changes in a B-mode echo image according to an embodiment of the present invention. FIG. 6 is a diagram showing changes in a B-mode echo image according to an embodiment of the present invention. FIG. 6 is a diagram showing changes in a B-mode echo image according to an embodiment of the present invention. The figure which shows the image of the displacement vector, strain tensor, and relative shear elastic modulus measured in the agar phantom by one Embodiment of this invention. The figure which shows the sound pressure change by one Embodiment of this invention when using a concave type HIFU applicator.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In addition, the same components will be denoted by the same reference numerals and redundant description will be omitted. The device according to the present invention can be used as a measurement imaging device or a communication device. In the following, the sound pressure or particle velocity is mainly used when the wave is a sound wave such as an ultrasonic wave, the compression wave (longitudinal wave) or shear wave as a mechanical wave, the shock wave, the surface wave, etc. When distorted waves and electromagnetic waves are targeted, electric field or magnetic field, and when thermal waves are targeted, image signals such as transmitted or refracted waves of temperature or heat flux, reflected waves, and scattered waves (forward scattered waves or backscattered waves) are displayed. The case of generation will be described.

<< First Embodiment >>
First, the configuration of the measurement imaging apparatus or the communication apparatus according to the first embodiment of the present invention will be described. FIG. 1 is a typical block diagram showing a configuration example of a measurement imaging apparatus or a communication apparatus according to the first embodiment of the present invention. As shown in FIG. 1, the measurement imaging apparatus (or communication apparatus) according to the present embodiment includes a transmission transducer (or applicator) 10, a reception transducer (or reception sensor) 20, a device body 30, and an input device 40. An output device (or display device) 50 and an external storage device 60.

  FIG. 2 is a typical block diagram showing in detail a configuration example of the apparatus main body shown in FIG. The device body 30 mainly includes a transmission unit 31, a reception unit 32, a digital signal processing unit 33, and a control unit 34. Here, the receiving unit 32 may include the digital signal processing unit 33. 1 and 2 are appropriately simplified block diagrams, and the present embodiment is not limited to these, and the details of the present embodiment are as follows. As an example, appropriate communication is performed between the above-mentioned devices, between units within the device main body 30 and within each unit, based on a wired or wireless technology, and may be installed at distant locations. The device main body 30 is composed of a plurality of such units, and is referred to as such for convenience.

<Transmit Transducer>
The transmission transducer (or applicator) 10 shown in FIG. 2 generates a wave by the drive signal supplied from the transmission unit 31 in the apparatus body 30, and transmits the wave. In the present embodiment, the plurality of transmitting aperture elements 10a of the transmitting transducer 10 form an array.

  FIG. 3 is a schematic diagram showing an arrangement example of a plurality of transmission aperture elements in a transmission transducer. FIG. 3 (a1) shows a plurality of transmission aperture elements 10a densely arranged in a one-dimensional array, and FIG. 3 (b1) shows a plurality of transmission aperture elements 10a sparsely present in one dimension. Is shown. FIG. 3 (a2) shows a plurality of transmission aperture elements 10a densely arranged in a two-dimensional array, and FIG. 3 (b2) shows a plurality of transmission aperture elements 10a sparsely present in a two-dimensional array. Is shown. FIG. 3 (a3) shows a plurality of transmission aperture elements 10a densely arranged in a three-dimensional array, and FIG. 3 (b3) shows a plurality of transmission aperture elements 10a sparsely present in a three-dimensional array. Is shown.

  Each transmitting aperture element 10a has a rectangular, circular, hexagonal, or other aperture shape, and can be flat, concave, convex, and the array can be one-dimensional, two-dimensional, or There are three-dimensional ones. The directivity of one transmission aperture element 10a is determined by the frequency and bandwidth of the generated wave and the shape of the aperture of the transmission aperture element 10a, and is usually expressed in a two-dimensional or more space, but at least orthogonal. One element may be counted as having two directions in which so-called openings are orthogonal to each other so as to have directivity in two directions, and three directions in which so-called openings are orthogonal so as to have directivity in three orthogonal directions. The one that is suitable for may be counted as one element. There is also an element having openings in which the openings are oriented in more than three directions so as to have directivity in more than three independent directions. They differ depending on the position and may be mixed.

  The transmission aperture elements 10a may exist spatially densely or sparsely (at distant positions), but this embodiment will be described without being particularly distinguished from the one-dimensional to three-dimensional array type. Aperture element array is used in IVUS for linear type (element arrangement is flat), convex (convex arc shape arrangement), focus type (concave arc shape arrangement), circular type (for example, medical ultrasonic wave). ), Spherical, convex or concave spherical shell shape, and other shapes arranged in a convex or concave shape, and various modes are taken for the object (communication object) and the observation object that propagate the wave. , But not limited to these. By appropriately driving these aperture element arrays, transmission and steering of waves in which the wavefront of the plane wave or the like broadens in the lateral direction, aperture synthesis, fixed transmission focus, etc. are performed, and one beam or generated beam is generated. A transmitted wave with a wavefront is realized.

  As for electronic scanning, as will be described later in detail, in order to generate one transmission beam or a transmission wave having a wavefront, its driving is performed by independent drive signals generated by a plurality of transmission channels included in the transmission unit 31 shown in FIG. The same number of transmission aperture elements 10a as the number of signals can be driven independently. The transmit aperture element array used to generate the transmit wave with one transmit beam or wavefront is also referred to as the transmit effective aperture. In addition, the full aperture element is distinguished from the physical aperture element array collectively referred to, and the transmission aperture realized by the transmission aperture element 10a driven simultaneously is also referred to as a transmission sub aperture element array or simply a transmission sub aperture. is there.

  In the case where the wave propagation target (communication target) is wide, or in order to observe the entire region of interest at once, the number of transmission channels is equal to the total number of aperture elements in the physical aperture element array, and all of them can be used at all times. However, in order to reduce the cost of the device, it is possible to electronically switch the transmission channel to shift the transmission sub-aperture element array (electronic scanning) or mechanically scan the physical aperture element array (mechanical scanning). , Waves may be transmitted over the region of interest using a minimum number of transmission channels. When the target (communication target) for propagating the wave is wide or the size of the observation target is large, both electronic scanning and mechanical scanning may be performed.

  When a sector scan is performed, a spatially fixed aperture element array of the type described above is electronically driven for scanning (electronic scanning), or the aperture element array itself is mechanically scanned. (Machine scanning), or both may be performed together. In classical aperture plane synthesis, electronic scanning is performed electronically for each element of the aperture element array, or mechanical scanning of one aperture element is performed to transmit at different positions to form a transmission aperture array. In the above, the transmission unit 31 may have the number of transmission channels equal to the number of elements of the physical aperture array. However, the number of transmission channels can be reduced by using a switching device, and at least one channel is always required like the mechanical scanning. Need. When transmitting polarized waves, at least the number of channels obtained by multiplying the number of elements driven at one time by the number of polarized waves is required for the transmission unit 31.

<Reception transducer>
The receiving transducer (or receiving sensor) 20 shown in FIG. 2 may also serve as the transmitting transducer 10, but it may be an array-type sensor that is used separately from the transmitting transducer 10 and is dedicated to reception. Therefore, the receiving transducer 20 may be set at a position different from that of the transmitting transducer 10. Further, the receiving transducer 20 may sense a wave different from the wave generated by the transmitting transducer 10. Such a receiving transducer 20 may be installed at the same position as the transmitting transducer 10 or may be integrated with it.

  Like the transmitting transducer 10, the receiving transducer 20 in the present embodiment has at least one or more receiving aperture elements 20a forming an array, and the signals received by the respective elements are independently stored in the device body 30. Is transmitted to the receiving unit 32 (FIG. 2). Like the transmit aperture element 10a, the receive aperture element 20a has a rectangular, circular, hexagonal, or other aperture shape, and can be flat, concave, convex, or an array of 1 There are three-dimensional, two-dimensional, or three-dimensional shapes. The directivity of one reception aperture element 20a is determined by the frequency and bandwidth of the received wave and the shape of the aperture of the reception aperture element 20a, and one having a plurality of apertures may be counted as one element. The number of openings in one element varies depending on the position and may be mixed. In addition, the receiving aperture elements 20a may exist spatially densely or sparsely (positions distant from each other), and are not distinguished from the array type here (see the example of the transmitting array in FIG. 3).

  The aperture element array is similar to that of the transmission transducer 10, and is linear (element arrangement is flat), convex (convex arc arrangement), focus type (concave arc arrangement), circular (for example, For the object (communication target) or the observation target that propagates the wave, such as medical ultrasonic waves used in IVUS), spherical, convex or concave spherical shell shape, and other things arranged in a convex or concave shape Therefore, various aspects are taken, and the present invention is not limited to these. Waves are received by using these aperture element arrays, and reception and steering of waves in which the wavefront of the above-mentioned plane wave widely spreads in the lateral direction, aperture plane synthesis, fixed reception focus, dynamic focus, etc. are performed. Received waves with beams and generated wavefronts are realized.

  Transducer apertures (elements) may not be spatially dense and may be sparse (distant positions), or may be mechanically scanned to transmit or receive a measurement target. The received signal may be processed in the same manner even when a transducer not called an array type is used, but in the present application, the case where an array type device is used will be emphasized without making a particular distinction between them. The present invention will be described. For example, each radar may or may not form an array when there are radar openings at remote locations on land.

  Not only the radar installed on satellites and airplanes, but also the transducer may mechanically scan the measurement target. In some cases, the signal is transmitted or received continuously continuously with high density, or spatially sparsely at distant positions. Therefore, in addition to classical aperture plane synthesis (transmission by a single aperture element), a signal may be received while performing transmission beamforming. The aperture element may exist in one dimension, or may exist in a two-dimensional or three-dimensional space. In addition, mechanical scanning may be performed while electronically scanning.

  Regarding electronic scanning, as will be described later in detail, in order to realize one reception beam or a reception wave having a generated wavefront, the reception unit 32 receives the reception signals independent of the number of reception channels at one time in the aperture element. It is possible (the effective reception aperture is determined). The receive effective aperture may be different than the transmit effective aperture. The full aperture element may be distinguished from a physical aperture element array collectively referred to, and the reception aperture realized by the reception aperture element 20a used at the same time may be referred to as a reception sub aperture element array or simply a reception sub aperture.

  In the case where a wave propagation target (communication target) is wide or in order to observe the entire region of interest at one time, the receiving unit 32 is provided with the number of receiving channels of the total number of aperture elements provided in the physical aperture element array, and these are always All may be used, but to make the device inexpensive, electronically switching the receive channel to transition the receive sub-aperture array (electronic scanning) or mechanically scanning the physical aperture array. The (mechanical scan) may also receive the incoming waves from the entire region of interest with a minimum number of receive channels.

  When the target (communication target) for propagating the wave is wide or the size of the observation target is large, both electronic scanning and mechanical scanning may be performed. When a sector scan is performed, a spatially fixed aperture element array of the type described above is electronically driven, and scanning is performed by alternately repeating transmission and reception (electronic scanning), or The aperture element array itself may be mechanically scanned (mechanical scanning), or both may be performed together. Further, in the classical aperture plane composition, regarding transmission, as described above, transmission is performed at different positions through electronic scanning that is electronically driven for each element of the aperture element array or mechanical scanning of one aperture element. In order to configure the transmission aperture array, the transmission unit 31 may have the same number of transmission channels as the number of elements of the physical aperture array in electronic scanning. Need.

  On the other hand, regarding the reception at that time, in the monostatic type in which only the same element as the active transmission element is used for reception, the reception unit 32 may have the reception channel similarly to the transmission channel. Further, in a multi-static type in which reception is often performed by a plurality of surrounding elements including an active transmission element, the reception unit 32 may have the same number of reception channels as the number of elements of the physical aperture array in electronic scanning. By using the switching device, it is sufficient that the receiving unit 32 has at least as many receiving channels as there are elements of the receiving effective aperture in both electronic scanning and mechanical scanning. When receiving polarized waves, at least the number of channels obtained by multiplying the number of receiving elements by the number of polarized waves is required for the receiving unit 32.

<Specific example of transducer>
There are various transducers 10 or 20 that can generate or receive arbitrary waves such as electromagnetic waves, light, mechanical vibrations, sound waves, or heat waves. For example, the transducer 10 may be capable of transmitting an arbitrary wave to the measurement target and receiving a reflected wave reflected in the measurement target, a backscattered scattered wave, or the like (also serving as the transducer 20). For example, when the arbitrary wave is an ultrasonic wave, it is possible to use an ultrasonic transducer that transmits an ultrasonic wave according to a drive signal and receives the ultrasonic wave to generate a reception signal. It is well known that the ultrasonic element (PZT (Pb (lead) zirconate titanate), polymer piezoelectric element, etc.) is different and the structure of the transducer is different depending on the application.

  In medical applications, narrow band ultrasonic waves have historically been used in blood flow measurement, but the inventor of the present application has found that the soft tissue displacement and strain (in the static case Including the case) and shear wave propagation (velocity) measurement, we have been the first in the world to use a wideband transducer for (echo) imaging. HIFU treatment is also the same, and continuous waves are sometimes used, but the inventor of the present application has also developed an applicator using a high-frequency type or broadband type device in order to realize high-resolution treatment. There is. When high-intensity ultrasonic waves are used, the tissue may be stimulated in a range that does not produce a heating effect, and a force source may be generated in the measurement target as described above, and a transducer for (echo) imaging is used. Sometimes. Heat treatment, force source generation, and (echo) imaging may be performed simultaneously. The same applies to other wave sources and transducers.

  In the digital signal processing unit 33, a plurality of force sources can be generated in the object temporally or spatially, and the propagation direction of shear waves can be controlled by superposing shear waves. It is possible to measure the anisotropy of shear modulus and its propagation velocity. Since the shear waves generated almost at the same time are physically overlapped, the shear waves may be separated under the spectral analysis after the shear waves are observed through ultrasonic displacement meter measurement. If they do not physically overlap, the shear waves generated by the respective force sources are observed by analyzing the ultrasonic signals, and the results are superposed to determine the propagation direction, propagation velocity, and propagation direction (viscosity). ) The shear modulus may be obtained, but it may also be obtained by observing the superposition of shear waves by superposing and analyzing the ultrasonic signals when the respective force sources are generated. The same applies when a heat source is generated and heat waves and thermophysical properties are observed. Hereinafter, various other processes are performed.

  The shape of heat source, force source, sound pressure can be adjusted by apodization of transmission and reception, delay (delay), radiation intensity, and by detecting transmitted waves or reflected waves when they are generated and optimizing them It is possible to realize a desired heat source, power source, and sound pressure. The shape of the signal may be observed with high sensitivity using a hydrophone, or the shape may be estimated by obtaining the autocorrelation function for the signal captured by the detector. Then, linear or non-linear optimization is performed. The propagation directions of shear waves and heat waves may be optimized. In each case, it is desirable to use the estimation results of mechanical properties and thermophysical properties.

  For example, when a concave applicator is used, it is possible to focus high-intensity ultrasonic waves on the focal position, and a wide band is formed in the lateral direction. However, since the sound pressure shape has a distribution that draws a foot from the focus position, the spectrum obtained after receiving the reflected wave or the transmitted wave is processed (filtering, weighting, etc.) to make the sound pressure shape an ellipse. It can be processed (Patent Document 7). It may be applied that the spectrum components in each direction of the wave or beam are confirmed as a spectrum in the same direction in the frequency domain. As a result, the quality of imaging is improved and the accuracy of displacement measurement is improved.

  As wave parameters and beamforming parameters, focus position with transmission focusing, plane wave, cylindrical wave and spherical wave without transmission focusing, deflection angle (including zero degree without deflection), with apodization or None, F number, transmission ultrasonic frequency or transmission band, reception frequency or reception band, different pulse shapes, different beam shapes, etc. To generate a wave or beam with new characteristics that cannot be generated by wave generation or beam forming by single transmission and reception (for example, when the waves or beams are crossed and overlapped to each other for lateral modulation or broadband, multi-focus) In the above case), the same effect may be obtained by performing the same process. The superposition may be performed at the same time in real time, or may be performed with respect to those received at different times in the same time phase of interest. Each of them may be subjected to reception beamforming and overlapped with each other, or may be subjected to reception beamforming after being overlapped with each other.

  A received signal obtained from a single wave or beam or a superposition of a plurality of those waves or beams may be weighted in the frequency domain to be broadened and super-resolution may be performed (higher resolution). . The method described in paragraph 0009 may be used together, and the observed wave may be subjected to the conjugate or reciprocal of the frequency response as an inversion of the beam characteristic. In addition, the conjugate of the observed wave or the conjugate of the frequency response may be applied (these are detection processes, and the square of the envelope is obtained by the former, and the self spectrum, that is, the autocorrelation function is obtained by the latter. can get). Super-resolution may be applied to the beam-formed (including aperture plane synthesis), or super-resolution to reception beamforming or no beamforming (transmission / reception signal for aperture plane synthesis). Beam forming may be performed after performing image processing.

  Further, in the displacement (vector) measurement, in order to improve the accuracy of the displacement component, the frequency in the displacement component direction may be increased. If high resolution is also required, it is necessary to widen the band. For example, the displacement measurement can be performed with high accuracy by discarding the low frequency spectrum and increasing the frequency. The amount of calculation can also be reduced. In the case of physically generating multiple waves or beams, or by dividing the spectrum by signal processing to generate multiple waves or beams, an over-determined system can be configured to perform highly accurate displacement measurement, etc. Sometimes it is done. Envelope detection, square detection, and absolute value detection are performed for imaging, but by overlapping a plurality of waves or beams after detection, speckle can be reduced and specular reflection can be emphasized.

  It should be noted that these treatments can be carried out not only when using ultrasonic waves and medical treatment, but also when electromagnetic waves are used and in various fields. For example, it is possible to observe audible sound waves using ultrasonic waves (that is, the Doppler effect), observe sound waves and heat waves using electromagnetic waves or light, and observe seismic waves using them. In conjunction with this, it is also possible to observe related physical properties (distribution).

  There are two types of transducers, contact type and non-contact type, each time through a matching material (in the case of ultrasonic waves, gel, water, etc.), or one in which the matching material is built in the transducer in advance (for ultrasonic waves. In this case, a matching layer) is used and the impedance matching of each wave is appropriately performed on the object to be measured. Aperture element level and array such as power and carrier frequency, band (wide band or narrow band, determines axial spatial resolution), waveform shape, element size (determines lateral spatial resolution), directivity, etc. The one designed for both performance is used (details are omitted). As an ultrasonic transducer, there is also a composite ultrasonic transducer in which PZT and PVDF are laminated to have both transmission acoustic power and wide band property.

  When forced vibration is generated by a drive signal, the drive signal may adjust or encode the frequency or band of the generated ultrasonic wave (with respect to reception, for signals within the band of the transducer). , Bands may be selected using analog or digital filters). In some cases, aperture elements having different characteristics such as frequency and sensitivity are arranged. Originally, medical ultrasonic transducers were handy and easy to use, but recently, a non-cable type transducer has been used together with a handy-sized device body. If the sound has a low frequency (for example, audible sound), there is a speaker or a microphone. Other wave transducers may, but need not, be implemented from similar perspectives.

  Alternatively, the transducer 10 may be a transmitting transducer that generates an arbitrary wave, and the transducer 20 may be a receiving transducer (sensor) that receives the arbitrary wave. In that case, the transmitting transducer transmits an arbitrary wave to the measurement target, and the sensor, the reflected wave or the backscattered scattered wave reflected in the measurement target, or the transmitted wave transmitted through the measurement target, Refractive waves, forward scatter, etc. can be received.

  For example, when an arbitrary wave is a heat wave, a heat source that does not intentionally generate sunlight, lighting, metabolism in the living body, etc. may be used, but an infrared warmer, a heater, etc. There are also relatively steady ones, ultrasonic transducers that transmit ultrasonic waves for heating that are often controlled according to drive signals (sometimes a force source is generated in the measurement target), electromagnetic wave transducers, lasers, etc. used. In addition, infrared sensors that receive heat waves and generate received signals, pyroelectric sensors, microwave and terahertz wave detectors, temperature sensors such as optical fibers, ultrasonic transducers (temperature dependence of ultrasonic sound velocity and volume change, etc. A change in temperature can be detected by using the property) or a nuclear magnetic resonance signal detector (the temperature can be detected by using a chemical shift of nuclear magnetic resonance). For each wave, a transducer is used that can receive it properly.

  CCD (charge coupled device) technology is used for optical digital cameras and mammography, and an integrated circuit and a sensor body may be integrated. The same technique is also applied to an ultrasonic two-dimensional array, which enables real-time three-dimensional imaging. A combination of a scintillator and a photocoupler is used to detect X-rays, but it has long been possible to observe them as waves. In capturing a high-frequency signal as a digital signal, it is effective to perform analog pre-processing for detection or modulation, reduce the frequency, perform AD conversion, and store in a memory or a storage device (storage medium). Sometimes digital detection is performed. These may be integrated with a transmitter or a receiver by a chip or a substrate.

  In addition, each aperture may form an array, for example, when the radar is located at a position distant from the land, and it may not be the case. The aperture may be mechanically scanned to provide a wide directivity. Apertures are spatially continuous, dense, spatially sparse at distant locations, even with regularity, such as evenly spaced, and irregular under physical constraints In some cases, it is installed. In addition, the position may be fixed with respect to the target (communication target) and the observation position where the wave is propagated, such as in the ocean, a building, or indoors. They may be dedicated openings for the transmission or reception of waves. Further, although each opening may serve as both, it may not only receive the response of the wave transmitted by itself, but may also receive the wave transmitted by another opening. In medical and biological observation, it is also called photoacoustic, and an ultrasonic wave generated by laser irradiation may be observed (a plurality of wave transducers may be integrated). According to the present invention, Photoacoustics by the combined use of the ultrasonic diagnostic apparatus and OCT, for example, not only the distinction between arteries and veins, it is also possible to measure the blood flow velocity in each (it is also possible to perform super-resolution it can). Alternatively, a magnetic substance having an affinity for the lesion may be intravenously injected as a contrast agent, and vibration such as ultrasonic waves may be applied to the affected area to observe electromagnetic waves. It may use radio waves to communicate with various mobile units.

  There are various transducers (arrays) used for passive observation such as seismic waves (seismometers), magnetoencephalography (SQUID array), brain waves, neural network (electrode array), radio waves (antenna), radar, etc. , It may be used to observe the wave source. The propagation direction of the incoming wave is obtained based on multidimensional spectrum analysis (past achievements of the inventor of the present application), and further, in the device of the present invention, a plurality of transducers or receiving effective apertures provided at different positions are provided. Even when the information about the propagation time cannot be obtained by using it (generally, the position of the wave source is calculated from the time when the wave is observed at multiple positions), the position of the wave source can be calculated geometrically. It is possible. Waves can be observed as continuous waves instead of pulse waves or burst waves. Through any processing, when the arrival direction of the wave is known, various beams can be steered and focused in that direction for detailed observation. In those processes, always receiving the beamforming while changing the steering angle, observing the obtained image or image, the spatial resolution, the contrast, the signal strength, or the like, with emphasis on the highly probable direction, or It is also possible to identify the direction of the wave source through multidimensional spectral analysis. Therefore, the transducer used in the device of the present invention may be equipped with a mechanism that is also used for steering and performs electronic scanning, mechanical scanning, or both scanning.

  As transducers that can demonstrate the effectiveness of the present invention, some of the typical transducers and special ones that are relatively familiar to us are enumerated. It is not limited, and various ones capable of generating or receiving arbitrary waves such as electromagnetic waves, light, mechanical vibrations, sound waves, or heat waves can be used.

<Beamforming>
Simultaneously, or at the same time, when the state of the object (communication object) or the observation object to propagate the wave is the same or substantially the same, or at different times or different time phases, one or more beam forming at each aperture. Alternatively, transmission or reception may be performed. Further, similarly, one or more beamforming, or transmission or reception may be performed with one combination of apertures. Similarly, each of the plurality of combinations of apertures may perform one or more beamforming, or transmission or reception. Further, in these cases, new data may be generated through linear or non-linear calculation using them, including the case where a plurality of beamforming or reception results are obtained. The received signals to be processed may be overlapped or originally overlapped.

  Further, for example, in a spatially movable object such as a radar mounted on a satellite or an airplane, the mounted aperture may or may not form an array, and the mechanical scanning In some cases, a wide directivity may be obtained, and a certain regularity such as spatially continuous and high density, spatially sparse at distant positions, or evenly spaced. Alternatively, transmission and reception may be performed irregularly as necessary. There are various moving objects such as cars, ships, trains, submarines, and mobile robots. In addition, it may be something that is distributed, living things, etc. that move regularly or randomly. In such cases, mobile communicators are used. An RFID (Radio Frequency Identification) tag, an IC card, or the like may be used.

  In that case, not only classical aperture plane synthesis (aperture plane synthesis based on transmission for each aperture element) is performed, but also receive beamforming may be performed while generating transmit beamforming. Moreover, mechanical scanning may be performed regularly or irregularly while performing electronic scanning, so that waves are appropriately propagated in a spatially wide range (communication), or a spatially wide range is appropriately observed. Sometimes Of course, by using a multi-dimensional array, the wave may be appropriately propagated in a spatially wide area (communication) or the spatially wide area may be appropriately observed only by electronic scanning (physical aperture). Not only becomes larger, but also multi-directional steering is possible).

  The mounted aperture may double as both the aperture for transmitting and receiving the wave, but it does not only receive the response of the wave transmitted by itself, but also receives the wave transmitted by any other aperture. Sometimes. In addition, a plurality of moving objects may be provided with an opening, and simultaneously, or a simultaneous phase in which the states of the target (communication target) and the observation target for propagating the waves are the same or substantially the same, or at different times or In another phase, there may be more than one beamforming or transmission or reception at each aperture.

  Further, similarly, one or more beamforming, or transmission or reception may be performed with one combination of apertures. Further, similarly, each of the plurality of combinations of apertures may perform one or more beamforming, or transmission or reception. In addition, in these cases, new data may be generated through linear or non-linear calculation using them, including the case where a plurality of beamforming or reception results are obtained. In the above, a combination of an aperture of a moving object and a fixed aperture may be used for an object (communication object) or an observation object for propagating waves.

  Thus, in the present embodiment, there are a plurality of transmission aperture elements 10a and a plurality of reception aperture elements 20a (one aperture element may also serve as the transmission aperture element 10a and the reception aperture element 20a), Beamforming is actively performed. In this active beamforming, arbitrary beamforming can be realized by digital processing without performing interpolation approximation at high speed through fast Fourier transform. In addition, substantially any focusing and any steering can be performed using a transducer array device having an arbitrary aperture shape.

  The transmission is generally performed in an orthogonal coordinate system determined by the shape of the physical aperture element array in order to emphasize the direction of each aperture element (a virtual sound source will be described separately). In order to generate a signal that directly represents a wave in a different display coordinate system, the main focus is to perform reception digital beamforming without performing interpolation approximation processing. Sometimes forming is also done. In addition, since a virtual source or a virtual receiver may be used, beamforming is performed as in the case of the physical aperture element array.

<Sending unit>
Next, the transmission unit 31 (FIG. 2) included in the device body 30 will be described. The transmission unit 31 includes a plurality of transmission channel transmitters 31a. The number of transmission channels is the number of lines for sending different drive signals to the aperture elements used for performing one beamforming. For example, there are various forms of this transmission channel as described below. The frequency, bandwidth, waveform, and directivity of the wave generated in each transmission aperture element 10a are determined by the transmission aperture element 10a and the transmission unit 31.

  When an impulse signal is applied to the transmitting aperture element 10a, a wave is generated which is determined by the shape (thickness, size and shape of the aperture) and material (a single crystal is a typical ultrasonic element) of the transmitting aperture element 10a. , The frequency and band of the wave generated by forcibly exciting the transmission aperture element 10a with a drive signal having a frequency, a bandwidth, and a waveform (which may be encoded) generated in the transmission unit 31. The width, waveform, and directivity are adjusted. The characteristics of the generated drive signal are set as parameters under the control of the control unit 34. The control unit 34 may recognize the transducer to be used, and the recommended setting may be automatically performed, but setting or adjustment using the input device 40 is also possible.

  Usually, in performing one beam forming, the transmission unit 31 is equipped with an analog or digital delay pattern in order to drive a plurality of aperture elements by drive signals with different delays. In some cases, a delay pattern that realizes a transmission focus position, a steering direction, and the like that can be selected using is used. These patterns are programmable, and the patterns to be used and selectable patterns may be installed through various media such as a CD-ROM, a floppy disk, or an MO depending on the purpose. In some cases, a program may be started to interactively select a pattern from the input device 40, or a delay (pattern) value may be directly input, or a file in which data is recorded may be read and set. There is a case. Particularly, in the case of an analog delay, the delay value used may be changed in an analog or digital manner, or the delay circuit or pattern itself may be replaced with another one or switched separately.

  In the device body 30 (FIG. 2), a command signal for generating a drive signal (which may be encoded) for driving the corresponding transmission aperture element 10 a is transmitted from the control unit 34 to the multi-channel transmitter 31 a. It These command signals may be generated based on command signals for starting beamforming for one frame. When the transmission delay is digital, for example, a digital delay may be applied using the command signal sent to the transmitter 31a for the first transmitting aperture element to be driven as a trigger, and the command signal may be sent to each transmitter 31a. is there. A digital circuit delay device may be used for the digital delay.

  Further, the drive signal itself generated in the transmitter 31a for the element to be driven first may be subjected to analog delay and transmitted to each aperture element. In this case, where an analog delay that does not require synchronization is used, the transmitter 31a can drive a plurality of transmitting aperture elements 10a with at least one transmitter. Therefore, the transmission analog delay may be provided before or after or inside the transmitter 31a or in the control unit 34, while the transmission digital delay may be provided inside or before the transmitter 31a or in the control unit 34. There is.

  The pattern may be selected by switching the analog circuit or the analog device, or the digital circuit or the digital device, and the delay of these delay devices may be changed under the control of the control unit 34. It may be programmable through installation, input settings, etc. Also, a delay device may be provided in the control unit 34. Further, when the control unit 34 is configured by a computer or the like as described below, a command signal delayed by software control may be directly output from the control unit 34.

  The control unit 34 and the digital delay are devices or computers having general-purpose calculation processing capability, PLD (Programmable Logic Device), FPGA (Field-Programmable Gate Array), DSP (Digital Signal Processor), GPU (Graphical Processing Unit), or , A microprocessor, a dedicated digital circuit, or a dedicated device. They are preferably of high performance (multi-core etc.) and may also be responsible for analog devices, AD converters 32b, memories 32c and / or digital signal processing units 33 for performing transmit or receive beamforming processes.

  In addition, the number of times of communication between devices, communication line capacity, wiring, or broadband wireless communication is important. In particular, in the present invention, when those functional devices are properly mounted on one chip or substrate ( If removable, there is). In addition, they may be directly mounted on a single chip or substrate (including stacking). Parallel processing may be performed. If the device is non-detachable, when the computer also serves as the control unit 34, it is possible to obtain much higher security performance than the security obtained under normal program control. On the other hand, current legislation will increasingly require disclosure of processing details.

  Some control software and delay values are directly coded or entered or installed. How to apply the digital delay is not limited to these. When this digital delay is performed in the transmission delay, an error determined by the clock frequency for generating the digital control signal is inevitably generated unlike the analog delay. Therefore, from the viewpoint of accuracy, the transmission delay is preferably the analog delay. Basically, it uses costs and uses high clock frequencies to reduce errors. On the other hand, the analog delay can be changed in an analog manner or can be programmable so that it can be digitally controlled. However, when the degree of freedom is lower than that of the digital delay and the cost is reduced, the delay pattern mounted as an analog circuit may be switched and used.

  The transmission apodization is performed by the energy of the drive signal for the aperture element and the temporal change of the amplitude of the time-varying waveform (which may be encoded). The drive signal is adjusted based on the calibration data of the conversion efficiency (conversion ability) of the drive signal of the aperture element to the wave. For other purposes, adjustment of the drive signal may be performed solely for calibration purposes. The command signal sent from the control unit 34 to the transmitter 31a may represent the waveform and phase information of the drive signal generated by the transmitter 31a as a time series, or the transmitter 31a recognizes and outputs a predetermined signal. It may be encoded so as to generate a drive signal, or may simply issue a transmission command to the transmitter 31a that generates a predetermined drive signal for the position of each aperture element to be driven within the effective aperture. It may be.

  Further, like the delay, the transmitter 31a may be programmable so as to generate a predetermined drive signal for the position of each aperture element to be driven within the effective aperture, and various forms are possible. A power supply and an amplifier are used to generate a drive signal, but power supplies with different amounts of power or energy supply and amplifiers with different amplification levels are used by switching or used simultaneously to generate one drive signal. In some cases, like the transmission delay pattern, it is directly set as described above or is programmable. The delays and apodizations can be implemented in the transmission unit in the same or different form at the same or different hierarchical levels.

  The transmission channel for driving the aperture element in the transmission effective aperture is switched through a switching device such as a shift register or a multiplexer, and the effective aperture at another position is used to scan the region of interest while performing beamforming. There is. Some delay elements have variable delay values, and the delay pattern (delay element group) may be switched. Further, steering may be performed in a plurality of directions in one effective opening, or steering may be performed in a plurality of directions while appropriately changing the opening position and the effective opening width.

  When switching a high voltage signal, a dedicated switching device is used. In addition, the apodization value of the apodization element may be variable in the transmission time direction or the array direction of the aperture element, and the apodization pattern (apodization element group) may be switched, and the aperture position, range direction, or steering direction may be changed. The beam shape may be adjusted depending on Specifically, it means that a transmitting element with an apodization value of zero is inactive and is off. Apodization also serves as a switch for the effective element and can also determine the effective aperture width (apodization in the aperture element array direction). If the function is a rectangular window, the switch is on, if it is not a constant value, it is weighted on).

  Regarding the delay pattern and the apodization pattern, the device body 30 may be provided with a plurality of patterns or may be programmable, and based on the response from the transmission target and the beamforming result by the receiving unit 32 described below, In the digital signal processing unit 33 (FIG. 2) in the device body 30 which will be described later, attenuation or scattering of waves (forward scattering or backscattering), transmission, reflection, refraction, or frequency dispersion of sound velocity in the medium in the propagation process. In some cases, the delay and intensity of the wave transmitted from each aperture, the steering direction of the beam or wavefront, the apodization pattern, etc. may be optimized.

  Note that there are a monostatic type and a multistatic type that are used in the transmission by the one-aperture element in the classical aperture plane synthesis, and the active transmission aperture element 10a operates under the switching or apodization as described above. Can be switched. In some cases, all transmitting elements have a transmitting channel including the transmitter 31a. In aperture plane synthesis, it is necessary to generate waves of sufficient intensity or energy, and the transmission apodization function itself is not always important. Substantially, aperture plane synthesis is usually performed at the same time as reception apodization in the phasing adder, and in the present invention, it is often performed at the digital signal processing unit 33 at the same time as reception apodization. The representative transmission unit of the present embodiment has been described above, but any transmission unit that can perform transmission beamforming can be used and is not limited to the description.

<Reception unit and digital signal processing unit>
Next, the receiving unit 32 and the digital signal processing unit 33 (FIG. 2) included in the device body 30 will be described. The reception unit 32 includes a receiver 32a for a plurality of reception channels, an AD converter 32b, and a memory (or storage device or storage medium) 32c. The frequency, bandwidth, waveform, and directivity of the reception signal generated by each reception aperture element are determined by the reception aperture element 20a and the reception unit 32. When a wave arrives at the reception aperture, a reception signal determined by the shape (thickness, size and shape of the aperture) of the reception aperture element 20a and the material (single crystal as a typical ultrasonic element) is generated. The frequency, bandwidth, and directivity of the received signal generated by the filtering process (which may also serve as an analog amplifier) in the unit 32 are adjusted. The generated reception signal is substantially adjusted based on the parameters (frequency characteristics such as frequency and bandwidth) of the filter set under the control of the control unit 34. The control unit 34 may recognize the transducer to be used, and the recommended setting may be automatically performed, but setting or adjustment using the input device 40 is also possible.

  A normal digital receiving unit or a digital receiving apparatus has such a function and further has a phasing addition function. That is, the DAS processing in the digital receiving unit or the digital receiving apparatus is to perform a phasing process on a plurality of received signals and add the plurality of received signals subjected to the phasing process. As the phasing process, the reception signals are AD-converted in the reception channels of the plurality of reception apertures and basically stored in a memory, a storage device, a storage medium or the like that can perform high-speed reading and writing, and It takes a lot of time to delay the received signal read from the storage destination by interpolation approximation processing in the spatial domain in order to perform phasing with respect to the position of interest. In (1), there is a method of multiplying a delay with high accuracy based on the Nyquist theorem by phase rotation by multiplying a complex exponential function (past invention of the inventor of the present application). In addition, in the storage destination, the reception signals of the respective reception openings may be stored at positions corresponding to the reception delays, and these reception signals are read and added, or they are further subjected to the above processing. Sometimes added.

  FIG. 4 is a block diagram showing a typical configuration of a receiving unit or receiving apparatus equipped with a phasing adder that implements phasing addition processing and its peripheral devices. The receiving unit (or receiving device) 35 shown in FIG. 4 performs a phasing addition process in addition to a receiver 35a for a plurality of receiving channels, an AD converter 35b, and a memory (or storage device or storage medium) 35c. It includes a phasing adder 35d that performs the phasing adder and another data generation unit 35e that digitally processes the generated image signal. For example, the other data generation unit 35e generates image display data, calculates displacement based on the Doppler method, calculates temperature by high-order calculation, and calculates the temperature with respect to the target. Analyze.

  Dynamic focusing is performed by performing this phasing addition process at each position in the region of interest. Originally, dynamic focusing was the term used in the direction of the range received at the effective aperture, but in fact it is not the case in the receive digital beamforming implemented by the present invention. The receiving unit 32 according to the embodiment of the present invention shown in FIG. 2 has a high-accuracy digital processing in which a calculation process for performing phasing addition (DAS) processing is different from the above-mentioned calculation processing represented by its name and does not require approximation processing. Beam forming is performed. Therefore, in the embodiment of the present invention, the digital signal processing unit 33 shown in FIG. 2 is used instead of the phasing adder 35d shown in FIG. In the digital signal processing unit 33, other data as described above may be generated based on the image signal.

  An ordinary phasing adder can be similarly realized by the digital signal processing unit 33 in the embodiment of the present invention, but in particular, the characteristic of the receiving unit 32 in the embodiment of the present invention is high speed and high accuracy. In order to realize the processing, the reception signal normally generated in the reception aperture element 20a is level-adjusted by analog amplification or attenuation and analog filtering (programmable, which operates under the frequency characteristics and parameters set through the control unit 34). In addition to ensuring signal strength and reducing noise using analog devices, such as analog signal processing, the advantage that analog signal processing is faster than digital signal processing allows linear or especially non-linear A high-speed memory (or a storage device or a storage medium) that includes effectively using a device that performs analog signal processing, AD-converts a signal obtained through those processes, and reads and writes the resulting digital signal. 32c.

  As the mounted digital signal processing unit 33, a device or computer having general-purpose calculation processing capability, PLD (Programmable Logic Device), FPGA (Field-Programmable Gate Array), DSP (Digital Signal Processor), GPU (Graphical Processing) Unit), a microprocessor, or the like is used, or a dedicated computer, a dedicated digital circuit, or a dedicated device is used, and the digital wave signal processing of the present invention is performed on the stored digital signal. Is given.

  It is important that those analog devices, the AD converter 32b, the memory (or storage device or storage medium) 32c, and the devices that are responsible for the digital signal processing unit 33 (multicore, etc.) have high performance. The number of communications, communication line capacity, wiring, or broadband wireless communication is important. Especially, in the present invention, when these functional devices are properly mounted on one chip or substrate (when removable, ), And may be directly mounted on one chip or substrate (including stacking). Parallel processing may be performed.

  When the device is non-detachable, when the computer also serves as the control unit 34, it is possible to obtain much higher security performance than the security obtained under normal program control. On the other hand, current legislation will increasingly require disclosure of processing details. Further, the digital signal processing unit 33 may also serve as the control unit 34 that sends a command signal to another unit and controls them.

  In the receiving unit 32 embodied in the present invention, the trigger signal (that is, the AD conversion is started by which the AD converter 32b starts sampling (AD conversion) of the received signal generated in the receiving transducer (or receiving sensor) 20) The acquisition start command signal for starting the storage of the digital signal in the memory (or the storage device or the storage medium) 32c is similar to the trigger signal used in a normal receiving unit. For example, one of the command signals generated by the control unit 34 may be used so that the transmitter 31a generates a transmission signal to the transmitting aperture element 10a to be driven. In the case of receiving a wave, a command signal for the element to be driven first, a command signal for the element to be driven last, or a command signal for driving another element is used. The AD conversion may be started by applying the digital delay of.

  These command signals may be generated based on command signals for starting beamforming for one frame. That is, the number of times the transmission trigger signal is generated is counted, and it is determined that the predetermined number or the number that may be a programmable parameter that is appropriately input by the input device 40 or the like is set by hardware or When confirmed in the control program, a command signal may be generated to start the generation of a new frame. Like the other parameters, the number may be installed through various media such as a CD-ROM, a floppy disk, or MO. There are various cases in which a program can be activated to interactively select from the input device 40, a numerical value can be directly input, or a file in which data is recorded is read and set. The number can be determined by using a DIP switch or the like. If it is not required that the number of reception delay patterns is large, a product obtained by multiplying the received signal by the installed analog delay pattern may be AD-converted.

  In order to realize reception dynamic focusing at a high speed, the product of the complex exponential function is applied to the signal in the frequency domain which is the past invention of the inventor of the present application, and the normal high speed is achieved without using the method based on the Nyquist theorem. When the reception digital delay is applied, an error determined by the sampling interval of the AD conversion is generated. Therefore, it is necessary to increase the sampling frequency of the AD converter 32b at a sufficiently high cost, or by using a highly accurate digital delay (phase rotation processing). There was no choice but to perform slow beamforming. On the other hand, according to the present invention, if the received signal is digitally sampled in synchronization as described above, high-speed received digital beamforming can be performed without causing such an approximation error. Such reception digital beamforming is also significantly faster than the method of calculating the product of complex exponential functions in the frequency domain, which is the past invention of the inventor of the present application.

  In the present invention as well, usually, the number of lines for sending the signal received by the receiving aperture element 20a used for performing one beam forming to the receiving unit 32 is the number of receiving channels. In that respect, the receiving unit 32 is as follows, and there are various types of receiving channels. That is, in order to apply different delays to the signals generated by the plurality of receiving aperture elements 20a in performing the normal beamforming once, the receiving unit 32 is equipped with the analog or digital delay pattern as described above. A delay pattern that realizes a reception focus position, a steering direction, and the like that the operator can select using the input device 40 may be used.

  These patterns are programmable, and the patterns to be used or selectable may be installed through various media such as a CD-ROM, a floppy disk, or an MO depending on the purpose. In some cases, a program may be started to interactively select a pattern from the input device 40, or a delay (pattern) value may be directly input, or a file in which data is recorded may be read and set. There is a case. Particularly in the case of an analog delay, the delay value used may be changed in an analog or digital manner, or the delay circuit or pattern itself may be replaced with another one or switched separately. Sometimes.

  When the reception delay is digital, the reception signals stored in the memory (or storage device or storage medium) 32c of each reception channel are read out and phased (added). In the apparatus of the present embodiment, the digital signal processing unit 33 delays the digital received signal, passes the digital received signal through a delay device of a digital circuit, or AD converter 32b and a memory (or a storage device or It is possible to delay the fetch start command signal from the control unit 34 for turning on the storage medium 32c. Therefore, the digital delay can be applied at any position after the inside of the AD converter 32b or in the control unit 34.

  In the case of analog delay, the delay can be applied at any position after the reception aperture element 20a has generated a reception signal or in the control unit 34. When the analog delay pattern is used, at least one receiver 32a can receive the reception signals of the plurality of aperture elements. Therefore, in the storage destination of the reception signal, the reception signal of each reception aperture may be stored at a position corresponding to the reception delay, or the reception delay may not be applied at all. The digital signal processing unit 33 may perform digital wave signal processing, which will be described later, (the digital signal processing unit 33 may also be able to perform normal phasing addition processing).

  The pattern may be selected by switching the analog circuit or the analog device or the digital circuit or the digital device. Further, the delay of those delay devices may be changed under the control of the control unit 34, or may be programmable through installation, input setting, or the like. Further, since the control unit 34 may be provided with a delay device, when the control unit 34 is configured by a computer or the like as described above, the command signal delayed is controlled under software control. It may be output directly from the unit 34.

  The control unit 34 and the digital delay may be a device or a computer having a general-purpose calculation processing capability, a PLD, an FPGA, a DSP, a GPU, a microprocessor, or the like, a dedicated digital circuit, or a dedicated device. They are preferably of high performance (multi-core etc.) and may also be responsible for analog devices, AD converters 32b, memories 32c and / or digital signal processing units 33 for performing transmit or receive beamforming processes.

  In addition, the number of times of communication between devices, communication line capacity, wiring, or broadband wireless communication is important. In particular, in the present invention, when those functional devices are properly mounted on one chip or substrate ( If removable, there is). In addition, they may be directly mounted on a single chip or substrate (including stacking). Parallel processing may be performed. If the device is non-detachable, when the computer also serves as the control unit 34, it is possible to obtain much higher security performance than the security obtained under normal program control. On the other hand, current legislation will increasingly require disclosure of processing details. Some control software and delay values are directly coded or input, and some are installed. How to apply the digital delay is not limited to these.

  In the present embodiment, based on the above trigger signal sent from the control unit 34 (FIG. 2) of the apparatus body 30, the trigger signal (command signal) for instructing the start of AD conversion is the AD of each reception channel. It is supplied to the converter 32b. In accordance with this command signal, AD conversion of the received analog signal of each channel and storage of the digitized signal in the memory (or storage device or storage medium) 32c are started. The transmission unit 31, the reception unit 32, and the digital signal processing unit 33 are under the control of the control unit 34 until the reception signals for one frame are all stored, the transmission aperture position, the transmission effective aperture width, or While changing the transmission steering direction, etc., the processing from transmission to storing the digital signal is repeated while changing the reception aperture position, the reception effective aperture width, or the reception steering direction etc. each time a wave or beam is transmitted. Every time one frame of received signals is stored, the received signal group is subjected to the digital wave signal processing method used in the present invention, that is, the digital beam forming method, to generate a coherent signal.

  Therefore, even if the device according to the present invention is equipped with the analog or digital delay described above, it is not always used as a delay for beamforming, and a memory, a storage device, or a storage medium is saved. In some cases, it is used to delay the timing of starting AD conversion of received signals and storing them in the memory (or storage device or storage medium) 32c in order to make effective use of them and shorten access time. The reception delay in beamforming is always mainly performed by the digital wave signal processing performed by the digital signal processing unit 33, and the saving and shortening of the access time are significant in the present invention. In addition, physical beamforming at the time of transmission (for example, a physical process using a computer or a dedicated device, which is different from that performed in soft beamforming using a computer or a dedicated device, etc. When performing classical aperture plane synthesis without performing processing such as focusing, steering, and apodization that may be performed at the time of reception or at the time of reception, the transmission delay is the same as the reception delay in digital wave signal processing. You can hang at the timing.

  From the above, according to the present invention, the receiving unit 32 is always provided with an independent analog or digital delay, a receiver 32a, an AD converter 32b, and a memory (or a storage device or a storage medium) in each reception channel. 32c and, if necessary, level adjustment by analog amplification or attenuation, an analog filter, and other analog arithmetic devices. That is, in the apparatus of the present invention, when the digital delay is performed by the reception delay, an error that depends on the clock frequency does not occur as in the analog delay unless a delay for beamforming is applied.

  In other words, an error determined by the clock frequency is always generated in the transmission digital delay, so it is necessary to use a high clock frequency to reduce the error at a high cost, but the reception digital delay does not need to do so. . If a digital delay is used as the reception delay, the accuracy is not lowered and the degree of freedom in setting the delay pattern is high. If an analog delay is used as the transmission delay, the accuracy is good and the clock frequency can be lowered. The analog delay can be changed in an analog manner or can be programmable so that it can be digitally controlled. However, the analog delay has a lower degree of freedom than the digital delay, and when the cost is reduced, the delay pattern mounted as an analog circuit may be switched or used by being replaced with an appropriate one. When a high degree of freedom is required to set the transmission delay pattern, it is necessary to operate the digital delay with a high clock.

  Hereinafter, the coherent signal generated by the beam forming itself of the present invention will be referred to as an image signal. The reception effective aperture elements and their positions are controlled similarly to the transmission effective aperture elements (described later). It should be noted that this digital beam forming is not always performed every time a received signal for one frame is stored. For example, the effective aperture width, a predetermined number other than that, or an appropriate input from the input device 40 or the like. It may be performed at each timing when a number of channels of hardware such as those set by the above or a number of received signals which may be a programmable parameter are stored (there are various input means as described above). Further, the image signals generated by the partial beamforming may be combined to form an image signal of one frame.

  In that case, the received signals that are processed at consecutive positions in the scanning direction may overlap, and when these received signals are combined, simple superposition is performed (overlapping in the frequency domain). In some cases, they may be combined and inverse Fourier transformed), in some cases appropriately weighted and superimposed, or in some cases simply connected. The number of stored reception signals can be confirmed in the hardware or the control program by counting the trigger signal (command signal that arrives from the control unit 34) for capturing the reception signal. The command signal for starting the one-frame digital wave signal processing generated by the control unit 34 for each frame can be similarly confirmed, and the one-frame image signal is appropriately continuously generated.

  The maximum achievable frame rate depends on the beamforming mode to be implemented, and basically depends on the wave propagation velocity, but in actual applications, it is the time required to digitally calculate one frame image signal. Decided. Therefore, it is useful to carry out the above-mentioned processing for partially generating the image signal by parallel processing. Further, as described above, the inventor of the present application has developed a multi-directional aperture plane synthesis, generates a reception beam at a plurality of positions and a reception beam in a plurality of directions with respect to one transmission beam, and performs multi-focusing. It is useful to do, and to do them at high speed, it is useful to do parallel processing. In either case, a reception signal for beamforming for one frame or a part thereof may be stored based on the above transmission and reception, and the digital wave signal processing according to the present invention described in detail later may be performed. In addition, when the image signal cannot be generated in real time, the frame rate may be lowered or the processing may be performed off-line.

  It should be noted that the reception apodization weights the reception signal in the reception channel of each aperture element, and may be variable in the range direction. It is not impossible to make it analog, but it is easy to make it digitally variable. In a normal receiving unit, when performing phasing addition, it is often performed at each position, each range position, etc. and is variable, but in the device of the present invention, it is performed in the digital signal processing unit 33. become. On the other hand, although it is rare that non-variable apodization is performed, in that case, the apodization is performed when the received signal generated by the aperture element is level-adjusted by analog amplification or attenuation.

  Although it has a different meaning from apodization, at least the level calibration may be performed based on the calibration data of the conversion efficiency (conversion ability) of the drive signal of the aperture element to the wave, and at the same time as the level calibration, the apodization is also performed. There are times when you are told. It may be used for such processing, or may nonlinearly expand or compress the dynamic range of the waveform of the received analog signal, and other analog devices such as nonlinear elements are used in each reception channel. Sometimes. The analog device used including these amplifiers and the like may be programmable, and the setting method may take various forms. Like other parameters, it may be set directly using various input devices. Normally, the delay and the apodization are implemented in the receiving unit 32 in the same or different form at the same or different hierarchical levels, but usually in a phasing adder, in the present invention. Can be implemented with a high degree of freedom in the digital signal processing unit 33.

  The receive channel of each aperture element within the receive effective aperture may be switched through a switching device such as a shift register or multiplexer, and the effective aperture at another position may be used to scan the region of interest while beamforming. Further, the delay value of the delay element may be variable, and the delay pattern (delay element group) may be switched. Further, steering may be performed in a plurality of directions in one effective opening, and steering may be performed in a plurality of directions while appropriately changing the opening position and the effective opening width. Access time may be shortened by saving the device or the storage medium. The effect of storing frequently used data in a small-sized memory that is easy to read and write is also great.

  In the present invention, the saving and shortening of access time are significant. The apodization element group forming the apodization pattern may be switched. The beam shape may be adjusted depending on the opening position, the range direction, and the steering direction. Specifically, it means that the receiving element with an apodization value of zero is inactive and is off, and apodization also serves as a switch for the effective element and can also determine the effective aperture width (apodization in the aperture element array direction). If the function is a rectangular window, the switch is on, if it is not a constant value, it is weighted on). Therefore, the apodization element is at the same level as the switch.

  In addition, when the delay pattern or the apodization pattern includes a plurality of patterns or is programmable, the digital signal processing unit 33 in the device body 30 propagates the propagation based on the response from the transmission target and the result of beamforming. Wave attenuation and scattering (forward scattering, back scattering, etc.), transmission, reflection, refraction, or frequency dispersion and spatial distribution of sound velocity calculated in the medium of the process are calculated and transmitted from each aperture and received at each aperture. Delay, intensity, steering direction of beam or wavefront, apodization pattern, etc. may be optimized.

  In the classical aperture plane synthesis, all the receiving elements may have a receiving channel including the receiver 32a. Normally, aperture plane synthesis is performed at the same time as reception apodization in the phasing adder, and in the present invention, aperture plane synthesis may be performed at the same time as reception apodization in the digital signal processing unit 33.

  Further, ultrasonic frequency and bandwidth as parameters in the transmission unit 31 and the reception unit 32, codes, delay patterns, apodization patterns, analog devices for signal processing, effective aperture width, focus position, steering direction, and , The number of times of transmission and reception required for performing beamforming are installed in each functional device in the unit through various media such as a CD-ROM, a DVD, a floppy disk, or an MO. Sometimes.

  In some cases, you can start the program and select them interactively from the input device 40, you can directly enter numerical values, select them on the operation panel of the input device 40, or you can select other files in which data is recorded. There are various cases, such as reading and setting. It is also possible to set them using a dip switch or the like. It may be due to replacement or switching of units. In addition, when measuring objects are selected or the transducers to be used are mounted on the device, the devices may be recognized and the device may automatically operate under the recommended parameters. Subsequent adjustments are possible. Further, when a functional device of an ordinary receiving unit is installed, an image image obtained by using the apparatus of the present invention and an image image obtained by a process including an interpolation approximation, which is performed through ordinary phasing addition, as appropriate. It is possible to compare

<Input device>
The input device 40 is used, for example, to set various parameter values as described above. The input device 40 itself includes various devices such as a keyboard, a mouse, a button, a panel switch, a touch command screen, a foot switch, and a trackball, but is not limited to them. Various parameters, such as general-purpose memory, USB memory, hard disk, flexible disk, CD-ROM, DVD-ROM, floppy disk, or MO, to install or upgrade the operating system (OS) and device software. It may set or update the value. The input device 40 is provided with various devices that can read data from a storage medium, or the input device 40 is provided with an interface and various devices are mounted and used as necessary.

  The input device 40 is used not only for setting parameters of various operation modes of the device according to the present embodiment, but also for controlling and switching the operation modes. When the operator is a human, those input devices 40 are also so-called man-machine interfaces, but are not necessarily controlled by humans. As described above, the parameter value, data, or control signal is received from another device through various standards and connectors, or is received through wired or wireless communication (that is, a communication device having at least a receiving function), and the same. It is not limited to the above example because the effect can be obtained. Dedicated or regular networks may be used.

  The input data are stored in a memory, a storage device, or a storage medium inside or outside the apparatus, and the functional device in the apparatus operates by referring to the stored data. Alternatively, when the functional device in the apparatus has a dedicated memory, data is written in the device and the operation setting is determined by software, updated, or set by hardware. Or it may be changed. In some cases, the calculation function in the device operates and, based on the input data, the resource of the device is taken into consideration, and the optimized setting parameter is calculated and used. The operating mode may be determined by a command. In addition, the wave to be measured (the type and characteristics of the wave, intensity, frequency, bandwidth, or code), and the object or medium that propagates (propagation velocity, physical property values related to the wave, attenuation, forward scattering, back scattering, In some cases, additional information regarding transmission, reflection, refraction, etc., or frequency dispersion thereof, etc. is given, and the received signal may be appropriately processed in analog or digital.

<Output device>
A typical output device 50 is a display device. The display device not only displays the generated image signal, but also displays various results measured based on the image signal as numerical values, images, and the like. Used to display. The image signal is converted into an image display or a moving image or still image format (scan conversion) by a calculation process, but a graphic accelerator may be used. A brightness image (gray image) or a color image may be displayed, and the meaning of brightness or color may be displayed on a scale (bar) or logo. In addition, the result may be displayed in a bird's-eye view or a graph, and the display method of the result is not limited to them.

  When the result is displayed, various parameter values and patterns (names) when the operation mode is operating may be appropriately displayed simultaneously as a logo or characters together with each operation mode. In addition, supplemental information and various data regarding the measurement target input from the operator or another device may be displayed. The display device may also be used to display a GUI (Graphical User Interface) used when setting each parameter value or pattern using the input device 40, or using a touch command screen. The input device 40 may also be used to specify an arbitrary position and an arbitrary range of an image to be displayed by enlarging the image and to display various numerical values.

  As the display device, various devices such as a CRT, a liquid crystal, or a device using an LED are used, but other than that, a dedicated three-dimensional display device or the like is used, and the display device is not limited thereto. In addition, the output data is not limited to being directly interpreted and interpreted by humans, and the device body (computer) understands the output data based on predetermined calibration data and calculation and displays the result. In some cases (for example, understanding the composition and structure of the measurement target from the spectrum analysis of the received signal), the output data is output to another device and interpreted by the other device, and the same device (for example, a robot) Alternatively, another device may apply the output data.

  One device may receive a plurality of types of waves and generate an image signal for data mining, fusion, or the like, or another device may be used to perform such a process. is there. The characteristics (intensity, frequency, bandwidth, code, etc.) of the generated image signal may be analyzed. As described above, the data obtained by the device according to the present embodiment may be used by another device, and substantially, the communication device having at least the transmission function may be one of the output devices 50. A dedicated or regular network may be used.

<Memory device>
The generated image signal and various results (numerical values, images, etc.) measured based on the image signal are stored in a memory, a storage device, or a storage medium inside or outside the device which also serves as the output device 50. Here, they are referred to as a “storage device” and distinguished from the display device. An external storage device 60 is also shown in FIG. When the image signal is stored, the operation mode, the setting parameter value, the supplementary information regarding the target input from the operator or another device, or various data may be stored together with the image signal. As the storage device, a general-purpose or special memory, a USB memory, a hard disk, a flexible disk, a CD-R (W), a DVD-R (W), a video recorder, an image data capturing device, or the like is used. The device is not limited to them. The storage device is appropriately used according to its application, including the amount of data to be stored, writing and reading times, and the like.

  The image signal or other data stored in the past may be read out from the storage device and reproduced, but the main part is that the storage device is important for storing the OS, device software, or setting parameters. Is. Each functional device may have a dedicated storage device. The removable storage device may be used by other devices.

  The device main body 30 reads out the image signal stored in the storage device, performs high-order digital signal processing, and re-synthesizes the image signal (frequency modulation by a linear process or non-linear process, wide band, multi-focus, etc.), Image processing (super-resolution, enhancement, smoothing, separation, extraction, CG conversion, etc.) of the image signal, displacement and deformation of the object, and other various temporal changes, etc. The measurement results may be output and may be displayed on the display device.

  Also, the stored measurement results include wave attenuation and scattering (forward scattering and back scattering, etc.), transmission, reflection, and refraction, which are read out and optimized for various parameters that generate an image signal. It is also used for computerization and may be stored in a storage device for use. The optimization is performed by a calculation function provided in the control unit 34 or the digital signal processing unit 33.

<Control unit>
The control unit 34 controls the operation of the entire device. The control unit 34 is composed of various computers, dedicated digital circuits, etc., and may also function as the digital signal processing unit 33. Basically, the control unit 34 performs wave transmission / reception and wave digital signal processing based on various control programs and various data read from the storage device in response to various requests input via the input device 40. The transmitter unit 31, the receiver unit 32, and the digital signal processing unit 33 are controlled so as to generate an image signal.

  When the control unit 34 is configured by a dedicated digital circuit, the parameter may be variable, but only a fixed operation may be realized in some cases, including the case of switching to switch the operation. When a computer is used as the control unit 34, the degree of freedom is high, including when performing a version upgrade. The basis of the control unit 34 is the number of aperture elements for transmission and reception (number of channels for each), the number of beams to be generated, the number of frames (some continue operation unless stopped without specifying), frame rate, etc. According to the above, by providing the transmission unit 31 and the reception unit 32 with the repetition frequency, the transmission / reception position information, and the like, the scanning control and the image signal generation control are performed. Also controls. In addition, various interfaces may be provided and various devices may be used in conjunction with each other.

  The device according to the present embodiment may be used as one of devices such as a general network and a sensor network, may be controlled by a control device of a network system, and may control a network device. It may be used as a device or may be a control device for controlling a locally configured network. An interface for that may be provided.

<Beamforming method>
Next, a useful high-speed operation through digital Fourier transform in the case of using a plurality of transmission / reception aperture elements (including arrayed elements), which is performed in the digital signal processing unit 33 of the apparatus body 30 shown in FIG. A digital beam forming method will be described. In digital signal processing, intermediate data generated in the calculation process and data to be used repeatedly may be stored in a storage device or a built-in memory as appropriate, and when multiple image signals are generated in the same phase. Also, the storage device is used efficiently. Sometimes small size memory comes in handy.

  The generated image signal may be displayed as a moving image or a still image on the output device 50 such as a display device, or may be stored in the external storage device 60 using a recording medium such as a hard disk. When the digital signal processing unit 33 is a computer, various languages can be used and the assembler is useful, but especially when the computer is operated under a high-level language program such as C language or Fortran. In some cases, optimization and parallel processing may be performed at the time of compilation to realize high-speed calculation. A general-purpose one such as a matlab (MatLab), various control software, or one having a graphic interface may be used, or a special one may be used.

  Hereinafter, as an example, the beam forming method used in the apparatus of the present invention will be described through the case where the wave is an ultrasonic wave. The beamforming methods that can be used in the present embodiment are the following methods (1) to (7). In method (7), in addition to various beamforming methods, the method is generated in the digital signal processing unit 33. The representative observation data will be disclosed.

  The method (1) has been required until now in performing wave number matching in the Fourier space in plane wave transmission and / or reception beam forming at the time of reception, including the case where the transmission direction is deflected (steering). This is a method that does not require approximation processing. The method (1) performs wave number matching in the case of performing deflection by performing wave number matching in the depth direction and the lateral direction by dividing the complex exponential function regarding the cosine and the sine of the deflection angle and multiplying the received signal. Including this, the measurement results are highly accurate as in the classical monostatic type aperture plane synthesis. Further, as the method (2), high-speed digital processing of deflection dynamic focusing by monostatic aperture plane synthesis will be disclosed.

  Further, as the method (3), high-speed digital processing of multi-static type aperture plane synthesis will be disclosed. In the digital monostatic type aperture plane synthesis for deflection, the centroid (center) or the instantaneous frequency of the multidimensional spectrum of the generated image signal is ideally expressed by using the deflection angle and the carrier frequency (described later). As described above, the wave number matching is performed in the same manner as in method (1) so that the wave vector becomes the carrier frequency multiplied by the sine of the deflection angle and the cosine. Can be realized with precision. On the other hand, the multi-static type aperture plane synthesis generates echo data frames containing echo signals received at the same position of multiple reception positions with respect to the transmission position by the number of reception elements, and in the frequency domain, each echo data frame is generated. The above-mentioned monostatic digital aperture plane synthesis processing is applied to the data frame, and the result of superimposing the processing results is inversely Fourier transformed to achieve high accuracy. As a result, the method (3) can generate echo data by the number of digital aperture plane synthesis processes equal to the number of channels of the receiving aperture, generate a so-called low spatial resolution image signal frame, and superimpose it on the high spatial resolution image signal. It is significantly faster than the conventional DAS (Delay and Summation) method for generating frames.

  By the way, in the DAS method, phasing is applied to the received signal at high speed by interpolating and approximating it in the spatial domain, and phasing is implemented with high accuracy in the frequency domain ( The past results of the inventor of the present application), and the received signals are summed in the spatial domain. The former has high speed but low accuracy, and the latter has high accuracy but extremely low speed.

  As a method (4), a method of performing digital dynamic focus reception with high accuracy during transmission fixed focus is disclosed based on the beamforming of the methods (1) and (3). As the method (5), for the application to convex or sector scan or IVUS, the echo data transmitted and received in the polar coordinate system is also processed through the Jacobi operation and displayed with high accuracy without interpolation approximation processing. It is disclosed that echo data can be generated directly in the Cartesian coordinate system of the system.

  Further, as the method (6), it is disclosed that even in the migration process, the present invention can be used to perform the process with high accuracy and at high speed without performing the interpolation approximation process. All the beam forming processes of the methods (1) to (5) can be performed based on the migration process. Finally, method (7) discloses these beamforming-based applications. These demonstrate that any beamforming based on focusing and steering can be performed.

Method (1): Plane wave transmission and / or plane wave reception beamforming (i) Echo signal (image signal) during plane wave transmission
FIG. 5 is a schematic diagram of transmission of a polarized plane wave. The plane wave transmission is a method in which all elements in a linear array type transducer simultaneously emit ultrasonic waves to emit plane waves. When the wave number is k and a plane wave having a wave number vector represented by the equation (0) is transmitted (x is the scanning direction, y is the depth direction, and the position of the receiving effective aperture element array is zero in the y coordinate. In the Cartesian Cartesian coordinate system), the sound pressure field at the position (x, y) is represented by the equation (1).

Here, A (k) is the frequency spectrum of the transmitted pulse and has the relationship of equation (2).

When there is a scatterer of reflection coefficient f (x, y _i ) at the depth y = y _i , the echo signal from this scatterer is represented by equation (3).
The angular spectrum of this equation is represented by equation (4).

Assuming that the frequency response of the probe is T (k), the angular spectrum at the aperture plane (y = 0) of the echo signal from depth y = y _i is expressed by equation (5) based on the principle of angular spectrum. To be done.

Therefore, by adding the angular spectra from the respective depths, the angular spectrum of the echo signal represented by equation (6) can be obtained.

Therefore, the echo signal (image signal) can be expressed by Expression (9) by this inverse Fourier transform by performing wave number matching as Expression (7) and Expression (8).

  Considering transmit and receive in reverse, arbitrary transmit beamforming (eg, deflection plane wave, deflected fixed focusing beam, steering dynamic focusing based on aperture synthesis, undeflected wave or beam, etc.) It is possible to realize a situation in which the wave arriving from the measurement target is received as a plane wave having a deflection angle θ (including a case of zero degree) when the measurement is performed on the measurement target. This idea has not been disclosed so far. Considering in this way, it is possible to receive waves at the same or different steering angles θ (zero degrees or non-zero degrees) when transmitting any beam or any wave at any steering angle (zero degrees or non-zero degrees). . Further, any wave source, any transmitting effective aperture array (for example, an aperture having the same shape as the receiving effective aperture array or an arbitrary shape different from the receiving effective aperture array, and having an aperture in any direction, or existing at another position) , Or an arbitrary wave transmitted from an effective aperture at the same physical aperture but at a different position), the reception beamforming can be performed in the coordinate system defined by the reception aperture.

  Incidentally, when the plane wave is transmitted, the steering is physically performed at the deflection angle α (including the case of zero degree), and the steering of the deflection angle θ (including the case of zero degree) of the method (1) is performed by software. Then, the plane wave is steered at the deflection angle (α + θ) (the transmission deflection angle finally generated is the average thereof). It can be considered that the soft steering (deflection angle θ) reinforces the physical transmission steering (deflection angle α) or realizes the pure plane wave transmission steering softly. It can be considered that the reception steering is performed by a plane wave.

  In the method (1), the plane wave is steered at the physical deflection angle α, the soft deflection angle θ, or the both deflection angles α + θ at the time of transmission, and the dynamic focusing is performed at the steering angle φ at the time of reception. In this case, the soft steering described in the method (2) may be performed, which will be described later (the deflection angle finally generated is the average of the transmission deflection angle and the reception deflection angle). In this case, it can be considered that the soft steering (deflection angle θ) reinforces the physical transmission steering (deflection angle α) or realizes purely plane wave transmission steering by software. In addition to the reception dynamic focusing (including the case where the deflection angle φ is zero degrees), it can be considered that the reception steering is performed by a plane wave in software.

  In these cases, soft transmission and reception can be considered in reverse. Even if the soft deflection plane wave transmission (including the case where the deflection angle is 0 degree) and the reception deflection dynamic focusing (including the case where the deflection angle is 0 degree) are interchanged, the processing is the same (equivalent). It is also possible to interpret that the signal generated by the transmission beamforming is physically received by the deflection plane wave (including the case where the deflection angle is zero degree) and beamformed. Normally, it is not rational to physically perform the transmission dynamic focusing with or without the deflection, but it can be interpreted as being physically received by the polarization plane wave.

  Also, use this method to perform arbitrary transmit beamforming (eg, deflection plane wave, deflected fixed focusing beam, steering dynamic focusing based on aperture plane synthesis, undeflected wave or beam, and many others). it can. That is, it is possible to handle an arbitrary wave or beam (for example, the above example) physically generated by beamforming by the same process using a plane wave for transmission. That is, reception beamforming (dynamic focusing or the like) can be performed regardless of any transmission. It can also be processed at once when a plurality of transmissions are made. Further, in addition to the transmission deflection angle (including the case where the steering angle is zero), it is possible to perform the steering of the plane wave or the dynamic focusing (including the case where the steering angle is zero) in the transmission or the reception by software. (The finally generated deflection angle is the average of the transmission deflection angle and the reception deflection angle). Further, as described above, transmission and reception can be considered in reverse, and various combinations of beamforming are possible. Beamforming is performed in each of transmission and reception, and plane wave processing may be performed for both transmission and reception in terms of software. The same applies to three-dimensional beam forming using a two-dimensional array described later.

J.-y. calculation method disclosed by Lu et al. (Non-Patent Documents 3 and 4) is based on the above theory, first, fast two-dimensional Fourier transform of the received signal with respect to time and space, R (k _x , k) is calculated, and then wave number matching is performed by Expression (7), and fast two-dimensional inverse Fourier transform is performed (also described in paragraph 0352). Wave number matching is performed through linear interpolation approximation or approximation with the nearest data itself, and it is necessary to oversample the received signal in order to obtain accuracy. Higher-order interpolation approximation may be performed, or the sinc function may be used. In the case of three dimensions, the fast three-dimensional Fourier transform and the fast three-dimensional inverse Fourier transform are similarly used. One feature of the present invention is that the wave number matching is performed without interpolation approximation. However, when it is applied to various beam forming as described in paragraphs 0190 to 0194, interpolation approximation processing is performed to perform high-speed approximation. Another feature is that a solution may be required.

(Ii) Calculation procedure of an echo signal (image signal) at the time of transmitting and / or receiving a plane wave according to the present invention A case of transmitting and / or receiving a plane wave having a deflection angle θ will be described below. In the present invention, the matching of the wave number is first performed in the lateral direction by multiplying by the complex exponential function (equation (9a)) before the Fourier transform of the received signal in space (horizontal direction), and then in the depth y direction. Is performed by multiplying by the complex exponential function (equation (9b)) excluding the above-mentioned lateral matching processing so as to have resolution in the depth y direction. . Of course, the deflection angle θ can be used not only at non-zero degrees but also at zero degrees. This process is not disclosed in prior art documents.

FIG. 6 is a flowchart showing digital signal processing when transmitting a polarized plane wave. The calculation procedure is as follows. First, in step S11, the received signal is Fourier-transformed with respect to time t (FFT is good) as shown in Expression (10).
However, when ω is the angular frequency (angular frequency) and c is the speed of sound, the wave number k = ω / c. From this, an analytic signal is obtained. Here, in accordance with the above description, the processing in which the core sign of the complex exponential function is positive is shown as the Fourier transform, but the sign of the kernel of the complex exponential function is calculated as negative, as in the normal Fourier transform. It is also possible. In any case, in the inverse Fourier transform to be calculated later, the complex exponential function whose sign is always the inverse of that in the Fourier transform is used. The same applies to the other methods (2) to (7).

Next, in step S12, matching processing is performed on the wave number k _x for deflection, and equation (10) is multiplied by equation (11). In step S13, the received signal is subjected to Fourier transform (FFT Then, the equation (12) is obtained. For the calculation of the product of the fast Fourier transform result (10) with respect to time t and the complex exponential function (11), the dedicated fast Fourier transform that directly generates the calculation result is useful.
By the way, the result of the equation (12) can also be obtained by directly calculating.

The received signal is decomposed into plane wave components by the two Fourier transforms. The angular spectrum created by each plane wave at an arbitrary depth y can be obtained by multiplying equation (13) and shifting the phase, as described above.

Further, in step S14, the matching process is simultaneously performed on the wave number ky by simultaneously multiplying the equation (14).

In step S15, the angular spectrum of each depth y is calculated. That is, the formula (16) is obtained by multiplying the formula (15).

The sound pressure field created by each plane wave component at the depth y is obtained as an equation (17) by performing an inverse Fourier transform (IFFT) on the horizontal direction x.
An image signal is obtained by adding a plurality of wave number k components (or frequency components) to this.

Here, the order of the integration of the wave number k (or frequency) and the spatial frequency kx can be exchanged. Therefore, even if the wave number k components of the angular spectrum are added together in step S16 and the inverse Fourier transform (IFFT) is performed on the wave number k _x in the lateral direction in step S17, an image signal is obtained in step S18. In this case, the calculation can be performed by one inverse Fourier transform, and the calculation is faster. The same applies to the other methods (1) to (6). The matching of the wave numbers for deflection is performed by the equations (11) and (14). Unlike the method of matching wave numbers through interpolation approximation in the frequency domain (Non-Patent Documents 3 and 4), the present invention does not perform approximation processing, and therefore can be calculated with high accuracy. Physically and mathematically, the wave number matching can be performed at the first Fourier transform, and the wave number matching can be performed at the last inverse Fourier transform. The same applies to the other methods (1) to (6).

Further, by using the two-dimensional aperture element array, an arbitrary wave is transmitted from the wave source located in an arbitrary direction toward the measurement target, and the wave coming from the measurement target is received as a plane wave to generate a three-dimensional wave. In the case of performing digital signal processing, for example, a Cartesian Cartesian coordinate system (x, y, z) using coordinates of an axial direction y determined by the direction of the aperture of a flat receiving aperture element array and lateral directions x and z orthogonal thereto. ), The zero-degree or non-zero-degree deflection angle formed by the direction received as a plane wave and the axial direction is expressed using the elevation angle θ and the azimuth angle φ , the Fourier transform is performed in the depth y direction and the lateral directions x and z. The three-dimensional Fourier transform of R ′ (k _x , k, k _z ) of the received signal is performed as in the case of performing the two-dimensional wave digital signal processing described above.
The wave number matching expressed as is performed without interpolation approximation as follows. Similar to the two-dimensional case, in applying various beam forming as described in paragraphs 0190 to 0194, wave number matching is performed by interpolation approximation processing according to equations (7 ') and (8'), There be carried out in that _{case, F (k x ', k} y', k z ') are three-dimensional inverse Fourier transform.

When the interpolation approximation processing is not performed in the wave number matching, first, the received signal is Fourier transformed in the axial direction y and the complex exponential function (C21) represented by using the wave number k of the wave and the imaginary unit i is multiplied in the lateral direction. Perform wavenumber matching on x and z,
Furthermore, the product can be implemented on an angular spectrum obtained by Fourier transforming in the horizontal directions x and z so as to have a resolution in the axial direction y, except for the effect of wave number matching performed in the horizontal directions x and z. Multiplying the complex exponential function (C22) and the complex exponential function (C23) at the same time performs wave number matching in the axial direction, where the wave numbers in the lateral direction are represented by k _x and k _z ,
By performing wave number matching without performing interpolation approximation processing, it is possible to directly generate an image signal in a Cartesian coordinate system. That is, the sound pressure field created by each plane wave component at the depth y is obtained by performing a two-dimensional inverse Fourier transform (IFFT) on the horizontal direction x and z and adding a plurality of wave number k components (or frequency components). To obtain an image signal. Of course, it can also be used when the deflection angle is zero degrees (that is, the elevation angle θ and the azimuth angle φ are zero degrees) or at least one of the angles is zero degrees.

  In the above calculation, only the signal component within the band determined by the transmission signal or within the band determined in consideration of the SN ratio of the reception signal is the calculation target. For example, when generating the analytic signal based on the equation (10), only the signal within the required band may be generated and stored (corresponding to downsampling). In the method or apparatus of the present invention, interpolation approximation processing is not performed when performing wave number matching, but by oversampling the echo signal in the depth direction and the lateral direction, there is an effect of being robust against noise that is mixed. is there. The same applies to the other methods (1) to (6).

  Further, in the formulas (13) to (15), the formula (C22), and the formula (C23), by determining the position coordinate and range in the depth y direction to be calculated, the interval between the coordinates, and the like, an arbitrary depth position and It is possible to generate an image signal in an arbitrary range in the depth direction or at an arbitrary interval or an arbitrary density in the depth direction without performing an interpolation approximation process (regardless of the presence or absence of downsampling described in paragraph 0206). , Up-sampling can be performed, and the down-sampling is effective in a range where the Nyquist theorem is satisfied, provided that a high-frequency signal component is intentionally subjected to out-of-band processing (filtering out). Regardless of the presence or absence of downsampling, downsampling is possible within the range where the Nyquist theorem is satisfied). Further, in the inverse Fourier transform in the lateral direction such as Expression (17), by defining the position coordinate and the range in the lateral x direction to be calculated (as necessary, the complex exponential function of the past invention of the inventor of the present application can be calculated). Analog phase shifting is performed by phase rotation using multiplication), an image signal in an arbitrary lateral position or an arbitrary lateral range can be generated without performing interpolation approximation processing. In the conversion, narrow the band in the horizontal direction (spatial low density) excluding the frequency coordinates of the high frequency band, or widen the band in the horizontal direction by zero-filling the angular spectrum (spatial high density). Through, through, it is possible to generate an image signal having an arbitrary interval and an arbitrary density in the horizontal direction without performing interpolation approximation.

  In this way, the image signal can be generated at any desired position, range, interval, and density. That is, it is possible to generate the image signal at an interval shorter than the sampling interval of the reception signal and shorter than the interval of the reception aperture element. It is also possible to make the intervals of the image signals coarse in each direction (however, the Nyquist theorem must be satisfied). In order to improve accuracy when performing wave number matching through interpolation approximation according to equations (7) and (8), or equations (7 ′) and (8 ′), the amount of calculation increases, but at the cost of It should be processed under proper oversampling. In that case, it should be noted that the number of data of the Fourier transform is increased unlike the case where the signal at an arbitrary position can be selectively generated when the interpolation approximation process is not performed. The same applies to the other methods (1) to (6).

  In a convex transducer, sector scan, or IVUS, when transmitting or receiving in the radial direction r of polar coordinates to generate a wide wave (cylindrical wave) in the direction of angle θ (FIG. 7), or in other aperture shapes, When performing the same beamforming (cylindrical wave) using a virtual source installed at the rear (see FIGS. 8A to 8C, Patent Document 7 and Non-Patent Document 8), in the above method, The Cartesian coordinates (x, y) may be read as polar coordinates (r, θ) for processing, and an image signal can be generated at the polar coordinates (r, θ). The same applies to spherical waves in a spherical coordinate system. Further, as shown in FIGS. 8B (d) to 8 (f), transmission or reception at an arbitrary distance position is performed by using the physical aperture element array represented by the polar coordinate system as described above or the physical aperture having an arbitrary aperture shape. Alternatively, both plane waves may be generated and beamforming may be performed in the same manner. It is equivalent to generating a virtual linear aperture array (or plane wave) at that distance position, and setting the distance position to zero corresponds to the case where the linear aperture array is virtually used. The distance positions can be set not only in front of the physical aperture but also in the rear, and a virtual linear aperture array (or plane wave) can be generated at those positions. The virtual linear aperture array may be used as a virtual receiver instead of a virtual source, or may also serve as a virtual source.

  FIG. 7 is a schematic diagram in the case of transmitting or receiving a wide wave in the angle θ direction in the radial direction in the polar coordinates (r, θ) (cylindrical wave transmission). FIG. 7A shows a cylindrical wave transmission using a convex aperture element array, and FIG. 7B shows a cylindrical wave transmission using a sector aperture element array. (C) shows cylindrical wave transmission using an IVUS (circular type) aperture element array. It should be noted that FIG. 7B shows an arcuate opening, but a flat opening may be used to perform the sector scan. Also, these apertures may be used to generate a focus beam.

  FIG. 8A shows a case where a wide wave is transmitted in the radius r direction in the angle θ direction of the polar coordinate system (r, θ) by using a virtual source installed behind a physical aperture having an arbitrary aperture shape (cylindrical wave transmission ) Is a schematic view. FIG. 8A (a) shows a cylindrical wave transmission using the linear aperture element array, and FIG. 8A (b) shows a cylindrical wave transmission using the convex aperture element array. (C) shows cylindrical wave transmission using another arbitrary aperture element array. The reception may be performed in the same manner. 8B (d) to 8 (f) show a case where a transmission plane wave is generated at an arbitrary distance position using a physical aperture element array represented by a polar coordinate system or a physical aperture having an arbitrary aperture shape. (In the figure, when the convex type aperture element array is physically used). When the distance position is set to zero, it virtually corresponds to the case where a linear aperture array is used (FIG. 8B (d)). The distance positions can be set not only in the rear (FIG. 8B (e)) of the physical aperture but also in the front (FIG. 8B (f)), and a virtual linear aperture array (or plane wave) is generated at those positions. You can also do it. The reception may be performed in the same manner. FIG. 8B (g) is a special case, for example, in the case where a linear array type transducer is physically used, a case where a cylindrical wave is generated using a virtual source behind the physical aperture is applied, and an arbitrary distance position It is a schematic diagram in the case of generating a plane wave or a linear array type transducer virtually expanded in the lateral direction. The reception may be performed in the same manner. The virtual linear array transducer may be used as a virtual receiver instead of a virtual source, or may serve as a virtual source.

  In the case of transmission focusing, there is a report in Non-Patent Document 6, and similarly, the result is obtained in polar coordinates (r, θ). For example, there is an effect that a wide FOV can be obtained. As a method different from Non-Patent Document 6, as one of the features of the present invention, the present method (1) is used for these, and steering having a steering angle also at the coordinate position of these polar coordinate systems (r, θ) It is possible to generate a beam, which is also the case when the following methods (2) to (4) and (6) are used, in which Cartesian coordinates (x, y) are changed to polar coordinates (r, θ). Should be replaced with "" and processed. However, when these beamformings are performed, it is necessary to perform interpolation processing in order to obtain the signal value at the coordinate position of the Cartesian coordinate system of the display system, and the phase rotation due to the product of the complex exponential functions in the frequency domain is performed. The strict interpolation processing used is performed over time, or the interpolation approximation processing is performed as a short-time processing with an approximation error. The same applies to spherical coordinates.

  Further, in those cases where beam forming is performed in a polar coordinate system, displacement measurement can be performed, for example, displacement component in the radius r direction or angle θ direction can be measured, or displacement components in both directions can be measured. The displacement vector can be measured. However, in order to obtain the measurement result at the coordinate position of the Cartesian coordinate system of the display system after the measurement, it is necessary to perform the interpolation process. The strict interpolation processing used is performed over time, or the interpolation approximation processing is performed as a short-time processing with an approximation error. The same applies to the spherical coordinate system.

  From the result of the displacement measurement, strain, strain velocity (tensor), velocity (vector), acceleration (vector) are obtained by partial differential processing using a differential filter, and further, mechanical characteristics (for example, bulk modulus or The shear elastic modulus (for example, Non-Patent Document 7), the elastic modulus tensor of an anisotropic medium, and the like, temperature, and the like may be obtained through calculation. When performing the interpolation approximation, it is often possible to reduce the calculation time by performing the approximation process and performing those calculations in the Cartesian coordinate system, but the calculation is performed in the polar coordinate system to obtain the result, and the interpolation approximation It is better to display by doing so, and the propagation of error can be reduced. That is, the only error that occurs in the process after the displacement measurement is the interpolation approximation when obtaining the final display data (a plurality of display data may be obtained from the same displacement data).

  It should be noted that, as described above, it is also possible to express the echo signal in the Cartesian coordinate system and perform displacement measurement and a series of measurement through the interpolation processing. Although an error occurs when the approximation process is performed in the interpolation process, the amount of calculation required for the whole is small. When performing measurement based on processing of other echo signals, the processing can be performed as described above. The same applies to three-dimensional beamforming using a two-dimensional array.

  Further, with respect to any of the above, similar processing can be performed for any orthogonal coordinate system other than the polar coordinate system.

  On the other hand, similarly, in the case of a convex type transducer, a sector scan, or IVUS, etc., when a wide wave is transmitted or received (cylindrical wave) in the radius r direction in the angle θ direction in polar coordinates (r, θ) (FIG. 7). And, using a virtual source installed behind a physical aperture of arbitrary aperture shape, transmit a wide wave in the radius r direction in the angle θ direction of the same polar coordinate system (r, θ) as in FIG. 7 (cylindrical wave). 8A (see FIGS. 8A to 8C), the method of directly generating the image signal in Cartesian coordinates is the method (5) and the methods (5-1) and (5-1 '), respectively. ) Etc. Further, by using the physical aperture element array represented by the polar coordinate system as described above or the physical aperture having an arbitrary aperture shape, transmission or reception or a plane wave of both is generated at an arbitrary distance position, and similarly, a beam is generated. Forming may be performed and an image signal may be generated in the Cartesian coordinate system (see FIGS. 8B (d) to 8 (f)). It is equivalent to generating a virtual linear aperture array (or plane wave) at that distance position, and setting the distance position to zero corresponds to the case where the linear aperture array is virtually used. The distance positions can be set in front of the physical aperture as well as behind the physical aperture, and virtual linear aperture arrays (or plane waves) can be generated at those positions. The virtual linear aperture array may be used as a virtual receiver instead of a virtual source, or may also serve as a virtual source. Similarly, the beamforming method will be described as method (5), method (5-1), and (5-1 '). In these cases, echo signal imaging, displacement measurement, and the like can be consistently performed in the same Cartesian coordinate system. The same applies to the polar coordinate system. In such a case, it is also possible to convert the echo signal and the measured value from the Cartesian coordinate system to the polar coordinate system through interpolation processing. The same applies to three-dimensional beamforming using a two-dimensional array. Transmission focusing may also be performed.

  Further, with respect to any of the above, similar processing can be performed for any orthogonal coordinate system other than the polar coordinate system. Further, as described above, the virtual source and the virtual receiver are not always installed behind the physical aperture, and may be installed in front of the aperture. This can be done (Patent Document 7, Non-Patent Document 8). As described above, the present invention is not limited to the above. Further, in wave number matching in these beam forming processes, an interpolation approximation process may be performed to obtain an approximate solution at high speed. In addition, any of them may be similarly processed in the methods (1) to (7).

  In addition, in the methods (1) to (7), the apodization processing of transmission or reception, or both of the reception signals is linear processing, and therefore can be performed at various timings. That is, it can be performed by hardware at the time of reception, or at various timings after reception by software. As described above, it may be physically apodized during transmission (the same applies below).

  Incidentally, as a matter of course, when receiving a transmitted wave instead of an echo signal for beamforming, the coordinate y is half the round trip distance (expressed as ct / 2 using the propagation time t). Rather, it is the distance (ct) from the aperture element in the coordinate system determined by the receiving aperture element array.

Next, a case of performing aperture plane synthesis will be described. There are monostatic type and multistatic type in aperture plane composition.
Method (2): Monostatic type aperture plane synthesis FIG. 9 is a schematic diagram of monostatic type aperture plane synthesis. Monostatic aperture plane synthesis is one in which one element of the array emits an ultrasonic wave and the element itself receives an echo. Also in the aperture plane synthesis, the echo signal (image signal) can be calculated by performing the wave number matching in the procedure of FIG.

Since transmission and reception are performed by the same element in the monostatic type aperture plane synthesis, the propagation path of sound to the scatterer at the time of transmission and the propagation path of reflected sound of the scatterer at the time of reception are the same. Therefore, in a Cartesian Cartesian coordinate system in which the position of the receiving effective aperture element array is zero in the y-axis direction, when steering is not performed (θ is 0 degrees), the wave number k is doubled as shown in equation (18a). (When reflected waves, s = 2, the same applies hereinafter), and the matching of the wave numbers represented by equations (7) and (8) is performed. In the case of a transmitted wave, k is used instead of 2k (s = 1, and so on).

When the steering angle θ is non-zero, the wave number is (0, k ₀ ) with the wave number k ₀ (= ω ₀ / c) expressed using the carrier frequency ω ₀ of the ultrasonic signal. Beamforming is performed to shift the spectrum to generate an image signal having the vector (sk ₀ sin θ, sk ₀ cos θ) as the centroid (center) or the instantaneous frequency of the multidimensional spectrum (see FIG. 10). That is, the wave number matching represented by the equation (18b) in the equations (7) and (8) is performed.

The signal processing is performed in the same manner as in the method (1), and in particular, the wave number matching is performed by using the ultrasonic wave instead of the complex exponential function (equation (9a)) before the Fourier transform of the received signal in space (transverse direction). By multiplying by a complex exponential function (equation (19a)) represented by using the carrier frequency ω _{0 of the} signal, first performing in the lateral direction, and with respect to the depth y direction, in order to have resolution in the depth y direction, In place of the complex exponential function (equation (9b)), the complex exponential function (equation (19b)) excluding the lateral matching processing (equation (19a)) is multiplied, and at the same time, the complex exponential function (equation (9c)) Instead, it is performed by multiplying by a complex exponential function (equation (19c)). Of course, it can also be used when the deflection angle is zero degrees. This process is not disclosed in prior art documents.

Further, for example, in the echo method (reflection method), the deflection angles of the transmission beam and the reception beam may be different, and in that case, assuming that the deflection angles of the transmission beam and the reception beam are θ _t and θ _r , respectively. In equations (7) and (8), wave number matching represented by equation (18c) is performed under s = 2.

The signal processing is performed in the same manner as in the case where the deflection angles of the transmission beam and the reception beam are equal to each other, and in particular, the wave number matching is performed before the complex exponential function (equation (19a)) is multiplied by a complex exponential function (Equation (19d)) expressed by using the carrier frequency ω ₀ of the ultrasonic signal, and is first carried out in the lateral direction. In order to have a resolution in the y direction, instead of the complex exponential function (equation (19b)), the complex exponential function (equation (19e)) excluding the lateral matching processing (equation (19d)) is multiplied, and at the same time, the complex exponential function is obtained. Instead of the exponential function (formula (19c)), a complex exponential function (formula (19f)) is multiplied. Of course, it can also be used when the deflection angles θ _t and θ _r are zero degrees. This process is also not disclosed in the prior art document.

From the equations (19a) to (19c) and the equations (19d) to (19f), the two-dimensional Fourier transform R ′ (k _x , k) of the received signal is expressed by the equations (7) and (8). It is possible to realize a situation in which each of the wave number matchings of Expression (18b) and Expression (18c) is performed without performing interpolation approximation. In contrast, there is be performed by performing the interpolation approximation process beamforming fast, in which _{case, F (k x ', k} y') are two-dimensional inverse Fourier transform. In the formulas (18b) and (18c), the approximation process including the approximate wave number matching process corresponding to the formula (18a) when the deflection angle is set to zero is not disclosed in the prior art document.

Further, when performing three-dimensional wave digital signal processing using the two-dimensional aperture element array, for example, the axial direction y (y of the position of the reception effective aperture element array is determined by the direction of the aperture of the flat reception aperture element array). Zero or non-zero deflection between the direction and axis of the beam produced in a Cartesian Cartesian coordinate system (x, y, z) using the coordinates (zero) and the transverse x and z coordinates orthogonal thereto. When the angle is expressed by using the elevation angle θ and the azimuth angle φ , the Fourier transform performs a three-dimensional Fourier transform with respect to the depth y direction and the lateral directions x and z (the wave number in the axial direction y and the lateral directions x and z is calculated. Considering wave number regions (k _x , k _y , k _z ) respectively defined as k _y , k _x , and k _z ), as in the case of performing the above two-dimensional wave digital signal processing, the following processing is performed. It

First, for a wave number vector (0, k ₀ , 0) having a wave number k ₀ (= ω ₀ / c) expressed using the carrier frequency ω ₀ of the wave, the wave number vector (sk ₀ sin θ cos φ , sk ₀ cos θ , sk ₀ sin θ sin φ ) as the centroid (center) of the multi-dimensional spectrum or the instantaneous frequency, in order to perform dynamic focusing of transmission and reception with spectrum shifting in order to generate an image signal, the received signal is Fourier-transformed in the axial direction y. A parameter s having a value of 2 when the y coordinate of the transmitting aperture element is zero and having a value of 1 when the y coordinate of the transmitting aperture element is non-zero, and the center of gravity (center) frequency k _{0 of the} wave , And a complex exponential function (C41) represented using the imaginary unit i, to perform wave number matching in the horizontal directions x and z,
Further, the product can be implemented by removing the effect of wave number matching performed in the horizontal directions x and z on the angular spectrum obtained by Fourier transforming the product in the horizontal directions x and z so as to have resolution in the axial direction y. Multiplying the exponential function (C42) and the complex exponential function (C43) at the same time performs wave number matching in the axial direction,
By performing wave number matching without performing interpolation approximation processing, it is possible to directly generate an image signal in a Cartesian coordinate system. That is, the sound pressure field created by each plane wave component at the depth y is subjected to a two-dimensional inverse Fourier transform with respect to the lateral directions x and z, and a plurality of frequency k components are added together to obtain an image signal. Of course, the calculation can be performed even when the deflection angle is zero degrees (that is, the elevation angle θ and the azimuth angle φ are zero degrees) or at least one of the angles is zero degrees.

As a result, the following wave number matching [Equation (C44)] is performed on the three-dimensional Fourier transform R ′ (k _x , k, k _z ) of the received signal as in Equations (7 ′) and (8 ′). You can realize the situation. While the above is intended to make this wavenumber matching without interpolation approximation, according to formula (C44), there is be performed at high speed by performing the interpolation approximation process, in which _{case, F (k x ', k} y', k _z ') is three-dimensional inverse Fourier transformed. This process is also not disclosed in the prior art document.

Further, for example, in the echo method (reflection method), the deflection angles of the transmission beam and the reception beam may be different, and in that case, the deflection angles are (elevation angle, azimuth angle) = (θ _t , φ _t ) And (θ _r , φ _r ), the signal processing is performed under s = 2 as in the case where the deflection angles of the transmission beam and the reception beam are equal, and in particular, The wave number matching is a complex exponential function (expressed by using the carrier frequency ω ₀ of the ultrasonic signal instead of the complex exponential function (equation (C41)) before the Fourier transform of the received signal in space (lateral direction) ( Equation (D41)) is first applied to the horizontal direction, and in the depth y direction, horizontal matching is performed instead of the complex exponential function (equation (C42)) in order to have resolution in the depth y direction. The complex exponential function (formula (D42)) excluding the processing (formula (D41)) is multiplied, and at the same time, the complex exponential function (formula (D43)) is multiplied instead of the complex exponential function (formula (C43)). . Of course, it can also be used when the deflection angles of the transmission beam and the reception beam are zero degrees (that is, θ _t , φ _t , θ _r , and φ _r are zero degrees). This process is also not disclosed in the prior art document.
It should be noted that in aperture plane synthesis in which both transmission and reception beamforming are performed by software, the same processing is performed even if these transmission and reception are interchanged.

As a result, the following wave number matching [Equation (D44)] is performed on the three-dimensional Fourier transform R ′ (k _x , k, k _z ) of the received signal as in Equations (7 ′) and (8 ′). The situation can be realized. While the above is intended to make this wavenumber matching without interpolation approximation, according to formula (D44), there is be performed at high speed by performing the interpolation approximation process, in which _{case, F (k x ', k} y', k _z ') is three-dimensional inverse Fourier transformed. This process is also not disclosed in the prior art document.

The aperture plane synthesis can generate arbitrary beamforming using the echo signals collected for aperture plane synthesis (not only in the monostatic method of the present method (2) but also in the multistatic method of the method (3)). However, an image signal can be generated by subjecting those data to the processing described in methods (1) and (4) to (7)). Also in the plane wave processing of the method (1), the aperture plane synthesis processing can be performed by using the reference sign. That is, it is possible to obtain a signal for aperture plane synthesis by decoding the coded received signal during plane wave transmission.
Further, as described in the method (1), it is possible to perform steering in the dynamic focusing. In the method (1), steering is physically performed at the deflection angle α (including the case of zero degree) at the time of transmitting the plane wave, and the steering of the deflection angle θ (including the case of zero degree) of the method (1) is performed. If applied, it can be interpreted that the plane wave is steered at the steering angle (α + θ) (the steering angle finally generated is the average thereof). Therefore, in the method (1), when the plane wave is steered at the deflection angle α or θ or α + θ at the time of transmission and the dynamic focusing is performed at the steering angle φ (including the case of zero degree) at the time of reception, The reception steering described in the method (2) may be performed, and the steering angle finally generated is the average of the transmission deflection angle and the reception deflection angle. Note that this soft plane wave steering (deflection angle θ) reinforces the physical transmission steering (deflection angle α) as described in method (1), or purely plane wave transmission steering can be performed softly. In addition to the reception dynamic focusing (including the case where the deflection angle φ is zero degrees), it can be considered that the reception steering is performed by a plane wave in software.

That is, in the case of two dimensions, (F41), (F42), and (F43) obtained by combining (9a) and (19a), (9b) and (19b), (9c) and (19c), respectively. The same process can be performed using.

In the three-dimensional case, that is, when a plane wave is physically transmitted by steering at a deflection angle (α, β) of an elevation angle α and an azimuth angle β, or when at least one of the angles is zero degrees, , In the case of performing steering dynamic focusing with the deflection angle (θ ₂ , φ ₂ ) by steering the plane wave with the deflection angle (θ ₁ , φ ₁ ) in software (at least one of the angles is 0 degree) (Including the case), (C21) and (C41), (C22) and (C42), (C23) and (C43), which are combined in the same manner as (G41), (G42), and (G43). In this case, the average deflection angle of the transmission deflection angle and the reception deflection angle can be finally generated.

  The processing is the same even if the soft transmission and reception beamforming are interchanged, and it is as described in the method (1) that it is equivalent to the interchanged beamforming. That is, even in these cases, the soft transmission and reception beamforming can be considered in reverse, and any physical transmission beamforming (eg, deflection plane wave, deflected fixed focusing beam, aperture plane) Various combinations of beam forming are possible in terms of software, such as steering dynamic focusing based on composition, undeflected waves and beams, and others). In addition to the steering angle (including zero) of any physically generated wave or beam (eg, the examples above), soft-wave steering (steering) of plane waves or dynamic focusing in transmission or reception. The angle can be zero (including zero). This soft plane wave steering can be thought of as, among other things, augmenting the physical transmit steering, or purely steering any physically transmitted wave or beam, or receiving dynamic focusing. In addition to the case where the angle φ is zero degrees, it can be considered that the reception steering is performed by software. The same applies to three-dimensional beamforming using a two-dimensional array. Besides, it is as described in the method (1).

Wave number matching in beam forming using equations (F41), (F42) and (F43) in the case of two dimensions and equations (G41), (G42) and (G43) in the case of three dimensions is performed through interpolation approximation. , Sometimes get results fast.
In the case of two dimensions, the wave number matching of equation (18b) or equation (18c) is interpolated and approximated together with equations (7) and (8) for the two-dimensional Fourier transform R ′ (k _x , k) of the received signal. performed expression (F 44)] _{through, F (k x ', k} y') are two-dimensional inverse Fourier transform. This approximation process is also not disclosed in the prior art document.
Further, in the case of three dimensions, for the three-dimensional Fourier transform R ′ (k _x , k, k _z ) of the received signal, the equation (C44) or the equation (D44) is used together with the equations (7 ′) and (8 ′). the wavenumber matching) performed through interpolation approximation expression (G44)], F (k x ', k y', k z ') are three-dimensional inverse Fourier transform. This process is also not disclosed in the prior art document.

  Further, in the case of a convex type transducer, a sector scan, or IVUS, etc., when a wide wave is transmitted or received (cylindrical wave) in the radius r direction in the polar angle (r, θ) in the angle θ direction (FIG. 7), When transmitting a wide wave in the radius r direction (cylindrical wave) in the angle θ direction of the same polar coordinate system (r, θ) as in FIG. 7 using a virtual source installed behind a physical aperture of arbitrary shape (See FIGS. 8A to 8C) and echo signals collected for aperture plane synthesis in the polar coordinate system, the Cartesian coordinates (x, y) are changed to polar coordinates (in the same manner as the method (1). The image signal can be generated in the Cartesian coordinate system (x, y) and the polar coordinate (r, θ) by replacing it with r, θ). Further, a plane wave of transmission or reception may be generated at an arbitrary distance position using the physical aperture element array represented by the polar coordinate system as described above or a physical aperture having an arbitrary aperture shape, and beamforming may be performed in the same manner (FIG. 8B (d)-(f)). It is equivalent to generating a virtual linear aperture array (or plane wave) at that distance position, and setting the distance position to zero corresponds to the case where the linear aperture array is virtually used. The distance positions can be set in front of the physical aperture as well as behind the physical aperture, and virtual linear aperture arrays (or plane waves) can be generated at those positions. The virtual linear aperture array may be used as a virtual receiver instead of a virtual source, or may also serve as a virtual source. The same applies when other transmission beam forming is performed or when they are performed in the spherical coordinate system. On the other hand, similarly, in the case of using a convex type transducer, a sector scan, IVUS, or the like, or in the case of using a virtual source installed behind a physical aperture having an arbitrary aperture shape, according to the method (5), An image signal can be generated in Cartesian coordinates. Further, a plane wave of transmission or reception may be generated at an arbitrary distance position using the physical aperture element array represented by the polar coordinate system as described above or a physical aperture having an arbitrary aperture shape, and beamforming may be performed in the same manner (FIG. 8B (d)-(f)). It is equivalent to generating a virtual linear aperture array (or plane wave) at that distance position, and setting the distance position to zero corresponds to the case where the linear aperture array is virtually used. The distance positions can be set in front of the physical aperture as well as behind the physical aperture, and virtual linear aperture arrays (or plane waves) can be generated at those positions. The virtual linear aperture array may be used as a virtual receiver instead of a virtual source, or may also serve as a virtual source. In these cases, echo signal imaging, displacement measurement, and the like can be consistently performed in the same Cartesian coordinate system. The same applies to the polar coordinate system. In these, similarly to the method (1), the same processing can be performed in an arbitrary rectangular coordinate system or by converting to an arbitrary rectangular coordinate system. In these, transmission focusing may be performed. Further, as described above, the virtual source and the virtual receiver are not always installed behind the physical aperture, and may be installed in front of the aperture. This can be done (Patent Document 7, Non-Patent Document 8). As described above, the present invention is not limited to the above. Further, in wave number matching in these beam forming processes, an interpolation approximation process may be performed to obtain an approximate solution at high speed.

  Further, the apodization processing of transmission, reception, or both of the reception signals can be performed at various timings because it is a linear processing (hardware at the time of reception, or softly after reception). As described above, it may be physically apodized at the time of transmission. In the case where the wave number matching is performed through interpolation approximation using the equations (7) and (7 ′), in order to improve the accuracy, the amount of calculation is increased, but the processing is performed under appropriate oversampling. There is a need. In that case, it should be noted that the number of data of the Fourier transform is increased unlike the case where the signal at an arbitrary position can be selectively generated when the interpolation approximation process is not performed. These processes are performed in the same manner as the method (1), and are also performed in the other methods (3) to (7).

Method (3): Multi-Static Open Area Synthesis FIG. 11 is a schematic diagram of multi-static open area synthesis. The multi-static type aperture plane synthesis is a method in which an ultrasonic wave is emitted from one element of an array and echoes are received by a plurality of elements around the element. A low resolution image signal is obtained for each radiation, and a high resolution image signal is generated by superimposing a plurality of low resolution image signals. The present invention may be used to generate this low resolution echo signal.

  As described above, usually, the conventional method is to generate a low-resolution echo signal from the echo signal received for each radiation of each element and superimpose them. On the other hand, in the present invention, a signal group consisting of signals having the same transmission / reception position relationship is set as one set, and digital monostatic type aperture plane synthesis is performed for each set to obtain a plurality by the method (3). The low-resolution image signals obtained are overlaid to complete the process. In practice, the overlay, which is a linear process, can be performed in the frequency domain before the inverse Fourier transform process in the lateral direction, which is faster, and the lateral alignment for performing the overlay is also At the time of superimposing, a complex exponential function for performing a horizontal shifting process is applied to rotate the phase in the horizontal direction, thereby performing at high speed, and an image signal can be generated without performing interpolation approximation. As the inverse Fourier transform, the fast inverse Fourier transform may be performed once. In addition, when performing the inverse Fourier transform in the horizontal direction to generate each low-resolution echo signal, at the same time, the phase is rotated in the horizontal direction by multiplying by the complex exponential function for performing the shifting process in the horizontal direction. It can also be overlapped in the area. In that case, a dedicated fast inverse Fourier transform may be implemented.

However, what is important is that, when applying the program of the monostatic aperture plane synthesis processing, when s = 2, if the distance in the x direction between the reception position at y = 0 and the transmission position at y = 0 is Δx, This is to calculate and use the converted distance y ′ of the propagation path until the signal is received at a position separated by Δx with respect to the distance y (coordinate y) of the point of interest. When the deflection angle is 0 degree, the equation (20a ) Is to calculate the reduced distance. Further, when s = 1, if the distance in the x direction between the receiving position of y coordinate y = 0 and the transmitting position of non-zero y coordinate y = Y is Δx, the distance y of the point of interest (coordinate y) is deflected. When the angle is 0 degree, the conversion distance represented by the equation (20b) is calculated (the y coordinate of the transmission position and the reception position may be considered oppositely).

  When the deflection angle is θ (including zero degree), multi-static aperture plane synthesis that generates a beam subjected to at least reception dynamic focusing (when s = 2, transmission dynamic focusing can also be realized) is performed. As a beam forming method to be performed, a wave is transmitted from each of the plurality of transmitting aperture elements in the transmitting effective aperture element array, and the wave arriving from the measurement object is transmitted by at least one of the plurality of receiving aperture elements at different positions. It receives and generates a reception signal (even if it is one, it can be processed by the device of the present invention), and the transmission aperture element is one in which the wave is generated by at least reflection or backscattering in the measurement object. (S = 2), or at least that which is generated by transmission, forward scattering, or refraction in the measurement object (s = 1) regardless of the x coordinate of the reception aperture element that generates the reception signal. Of any of a plurality of transmitting aperture elements that have an arbitrary x coordinate and a y coordinate of zero and that also serve as any of the receiving aperture elements in the array of receiving effective aperture elements, or that are different from any of the receiving aperture elements. One by one, or one by one of a plurality of transmitting aperture elements in the transmitting effective aperture element array having a constant non-zero y-coordinate and facing the receiving effective aperture element array (s = When 1, the y-coordinates of the transmission position and the reception position may be considered as opposites).

That is, when steering is performed, the steering process described in method (2) is applied to each of the monostatic type aperture plane synthesis data groups generated by the same combination of the positions of the transmitting element and the receiving element. It may be applied and similarly processed. The same applies when the steering angles for transmission and reception are different. However, even when the deflection angle is non-zero, when applying the program of the monostatic type aperture plane synthesizing process, as in the case where the deflection angle is zero degree, the distance y (coordinate y) of the point of interest is s = 2, the conversion distance represented by formula (20a) is used, and when s = 1, the conversion distance represented by formula (20b) is used. Therefore, similarly to the methods (1) and (2), in the program capable of deflecting, the deflection angle may be set to zero degree or non-zero degree and the processing may be performed.
In addition, the transmission can be performed when the plane wave of the method (1) is transmitted, and also when the arbitrary transmission beamforming such as fixed focusing is performed.

As another method, the y-coordinates of the transmission and reception aperture elements are zero for each of the reception signal groups obtained by arranging the reception signals having the same distance Δx in the lateral coordinate between the transmission position and the reception position. When (s = 2), between the transmission aperture element and the interest point and the reception aperture element, which are expressed using the deviation angle θ, the y coordinate of the interest point including the positions of the transmission and reception apertures, and the distance Δx. When the distance is half the straight line distance (equation (20c)) or the y coordinate of the transmission aperture element is non-zero (s = 1, the y coordinates of the transmission position and the reception position may be considered opposite). , The deviation angle θ, the y coordinate of the interest point, the y = Y coordinate of the transmission aperture element, and the distance Δx between the transmission aperture element, the interest point, and the reception aperture element (equation (20d)). The image signals obtained by setting the deflection angle in the monostatic aperture plane synthesis described above are corrected with respect to the lateral position in the frequency domain, and the image signals are superimposed without performing interpolation approximation processing. Can be generated. Although the spatial resolution in the depth direction is reduced, a large steering angle can be generated.

When three-dimensional wave digital signal processing is performed using the two-dimensional aperture element array, for example, the axial direction y determined by the orientation of the aperture of the flat reception aperture element array and the lateral directions x and z orthogonal thereto. In the Cartesian Cartesian coordinate system using the coordinates of, the same processing can be performed, and the deflection angle of zero degree or non-zero degree formed by the generated beam direction and the axial direction is represented by the elevation angle θ and the azimuth angle φ. In, the wave is transmitted from each of the plurality of transmitting aperture elements in the transmitting effective aperture element array, and the wave coming from the measurement object is received and received by at least one of the plurality of receiving aperture elements at different positions. A signal is generated, and its transmission aperture element has a wave generated by at least reflection or backscattering in the measurement object (s = 2), or at least transmission, forward scattering, or refraction in the measurement object. The generated x-coordinates and z-coordinates do not depend on the x-coordinates and z-coordinates of the receiving aperture element that generates the reception signal, and the y-coordinate of zero is set as the generated one (s = 1). Having either one of the receiving aperture elements in the array of receiving effective aperture elements, or one of a plurality of transmitting aperture elements different from any of the receiving aperture elements, or having a non-zero constant y coordinate, It is one of a plurality of transmitting aperture elements in the transmitting effective aperture element array at a position facing the receiving effective aperture element array (when s = 1, the y coordinates of the transmitting position and the receiving position are considered in reverse. May be). Whether the deflection angle is zero degrees (without steering) or non-zero degrees (with steering), similar to the two-dimensional wave digital signal processing using the one-dimensional aperture element array, the transmission element and the reception element The processing with or without steering described in the method (2) may be applied to each of the monostatic type aperture plane synthesis data groups generated by the combination having the same position, and the same processing may be performed. The same applies when the steering angles for transmission and reception are different. However, what is important is that when applying the program of the monostatic type aperture plane synthesis processing regardless of whether the deflection angle is 0 degree (without steering) or non-zero degree (with steering), when s = 2, y If the distance in the x direction (horizontal direction) between the receiving position of = 0 and the transmitting position of y = 0 is Δx, and the distance in the z direction (elevation direction) is Δz, the signals are received at positions separated by Δx and Δz in two directions. It is to calculate and use the reduced distance y ′ of the propagation path up to, and to calculate the reduced distance represented by the equation (20e). Further, when s = 1, if the distance in the x direction between the receiving position with y coordinate y = 0 and the transmitting position with non-zero y coordinate y = Y is Δx and the distance in z direction is Δz, then according to equation (20f). It is to calculate the conversion distance represented (y-coordinates of the transmission position and the reception position may be considered oppositely).

  In addition, the transmission can be performed when the plane wave of the method (1) is transmitted, or when any transmission beamforming such as fixed focusing is performed.

Alternatively, as another method, transmission and reception are performed for each reception signal group obtained by arranging reception signals having the same distances Δx and Δz in the horizontal x-coordinate and z-coordinate between the transmission position and the reception position. When the y coordinate of the aperture element is zero (s = 2), the elevation aperture θ and the azimuth angle φ , the y coordinate of the interest point including the aperture positions of the transmission and reception, and the transmission aperture represented by the distances Δx and Δz. Half the distance of the straight line connecting the element, the point of interest and the receiving aperture element, or the y coordinate of the transmitting aperture element is non-zero (s = 1, the y coordinates of the transmitting position and the receiving position may be considered conversely. Between the transmitting aperture element and the interest point and the receiving aperture element expressed by using the elevation angle θ and the azimuth angle φ , the y coordinate of the interest point, the y coordinate of the transmission aperture element, and the distances Δx and Δz. Using the distance of, correct each of the image signals obtained by setting the deflection angle in the above-mentioned monostatic aperture plane synthesis in the frequency domain, and superimpose them to perform interpolation approximation processing. Image signals can be generated without Although the spatial resolution in the depth direction is reduced, a large steering angle can be generated.

  Further, in order to generate an image signal representing the propagation of an unknown wave source or a wave generated by it (so-called passive mode), the y coordinate of the estimated unknown wave source is set to the y coordinate of the transmission aperture element, Beamforming is good. It is also effective to observe while changing the y coordinate by trial and error. For example, effects such as image formation, high spatial resolution, high signal strength, and high contrast may be obtained, and a series of processing is automatically performed using these as criteria. Is also possible.

  As will be described later, the information about the wave source position or the transmission aperture element may be given a position with respect to the reception aperture element, a direction or distance of an existing position, a direction of the aperture, or a propagation direction of the generated wave. Moreover, the time when the wave is generated may be given by an arbitrary wave source. It may be observed by other devices, or the received signal itself or the wave propagating faster than it may be emitted and transmitted from the wave source.

  For the received signal, the centroid (center) frequency or the instantaneous frequency of the multidimensional spectrum is obtained, and from this, the direction in which the wave source exists or the propagation direction of the wave is obtained, and the deflection angle for transmission or reception is adjusted to obtain the beam. Forming may also take place. For the beamformed image signal, the centroid (center) frequency or the instantaneous frequency of the multidimensional spectrum is obtained, and from this, the direction in which the wave source exists or the propagation direction of the wave is obtained, and the deflection angle of transmission or reception is determined. May be adjusted to perform beamforming. It is also possible to perform these processes in a plurality of reception apertures or reception effective apertures to geometrically determine the position or direction in which the wave source exists. These processes are useful and may be applied to other beamforming.

  As described in the method (2) of monostatic type aperture plane synthesis, also in the multistatic type aperture plane synthesis of the method (3), arbitrary beamforming can be generated by using the echo signals collected for aperture plane synthesis. (Actually, an image signal can be generated even if those data are subjected to the processes described in methods (1) and (4) to (7)). It may be effective that the amount of data is abundant as compared with the monostatic type, but the amount of calculation increases. Also in the plane wave processing of the method (1), the aperture plane synthesizing processing can be performed by using the sign. Further, in the case of a convex type transducer, a sector scan, or IVUS, etc., when a wide wave is transmitted or received (cylindrical wave) in the radius r direction in the polar angle (r, θ) in the angle θ direction (FIG. 7), When transmitting a wide wave in the radius r direction (cylindrical wave) in the angle θ direction of the same polar coordinate system (r, θ) as in FIG. 7 using a virtual source installed behind a physical aperture of arbitrary shape (See FIGS. 8A to 8C) and echo signals collected for aperture plane synthesis in the polar coordinate system, the Cartesian coordinates (x, y) are changed to polar coordinates (in the same manner as the method (1). The image signal can be generated in the Cartesian coordinate system (x, y) and the polar coordinate (r, θ) by replacing it with r, θ). The same applies when other transmission beam forming is performed or when they are performed in the spherical coordinate system. On the other hand, similarly, in the convex type transducer, sector scan, IVUS, or the like, the image signal can be directly generated in Cartesian coordinates according to the method (5). In that case, echo signal imaging, displacement measurement, and the like can be consistently performed in the same Cartesian coordinate system. In these, similarly to the method (1), the same processing can be performed in an arbitrary rectangular coordinate system or by converting to an arbitrary rectangular coordinate system. In addition, beamforming described in paragraphs 0209 to 0220 and the like of method (1) and paragraph 0238 and the like of method (2) can be performed in the same manner. It can be installed arbitrarily regardless of the shape (Patent Document 7, Non-Patent Document 8). Further, the present invention is not limited to this (hereinafter, the same).

  Further, as described above, although the spatial resolution in the depth direction is lowered, it is possible to perform deflection by another method in order to generate a large steering angle. Even in that case, the transmission beam forming and the reception beam forming are performed. The case where the steering angles are different can be similarly processed. The converted distance may be calculated using the lateral distance between the transmission aperture element and the reception aperture element, the transmission steering angle and the reception steering angle, and in the case of the transmission type, the distance between the transmission aperture element and the reception element.

  Basically, any steering in the method (3) is performed by software. Also, apodization may or may not be performed during transmission. Further, since the reception apodization process is also a linear process, it can be performed at various timings (hardware or software). It can be easily implemented at an appropriate timing by taking into account the amount of calculation that depends on the effective aperture width that determines the number of For example, each set may be weighted to initiate the generation of the low resolution echo signal, or the generated low resolution signal may be apodized in the frequency or spatial domain.

In applying the monostatic aperture plane synthesis of the method (2), wave number matching may be performed at high speed through the above-described interpolation approximation. In the interpolation approximation, linear interpolation approximation or approximation by the nearest data itself may be performed, high-order interpolation approximation may be performed, or sinc function may be used. In order to improve the accuracy of wave number matching through the interpolation approximation, it is necessary to perform processing under appropriate oversampling at the cost of increased calculation amount. In that case, it should be noted that the number of data of the Fourier transform is increased unlike the case where the signal at an arbitrary position can be selectively generated when the interpolation approximation process is not performed.
Further, in the horizontal alignment for performing superposition described in paragraphs 0241, 0245, and 0248, a complex exponential function for performing horizontal shifting processing is applied to rotate the phase in the horizontal direction. Alternatively, spatial shifting may be performed through interpolation approximation to achieve faster processing. In the interpolation approximation, linear interpolation approximation or approximation by the nearest data itself may be performed, high-order interpolation approximation may be performed, or sinc function may be used. Even in this case, in order to improve the accuracy of the interpolation approximation, it is necessary to perform processing under appropriate oversampling at the cost of an increase in the amount of calculation.

Method (4): Fixed Focusing FIG. 12 is a schematic diagram of fixed focusing using a linear array. The fixed focusing is a method of setting one point as a focus point and delaying each element so that the ultrasonic waves reach the focus point at the same time. A part or all of the physical aperture of the array type transducer is received as an effective aperture, and the measurement target is scanned. Of course, sometimes steering is performed. The steering angles of transmission and reception may be different.

The fixed focusing is performed by method (1): beam forming during plane wave transmission, or method (3): multi-static aperture plane synthesis, or method (1) plane wave transmission beam forming and method. This is performed by a method that combines the reception dynamic focusing of (2) or method (3). In that case, there are the following three methods.
(I) Image signal generation processing is performed once for each received signal obtained in the effective aperture width.
(Ii) A so-called normal low-resolution image signal is generated using the reception signal for each transmission, and they are superimposed.
(Iii) Similar to the multi-static type aperture plane synthesis, those having the same transmission / reception positional relationship are set as a set to generate image signals and superpose them.

  When transmitting and receiving in the radius r direction of polar coordinates in a convex type transducer or sector scan or IVUS, or when performing beamforming using a virtual source installed at the rear in an arbitrary aperture shape, Cartesian coordinates ( It is only necessary to replace (x, y) with polar coordinates (r, θ) for processing, and an image signal can be generated at polar coordinates (r, θ). As mentioned above, interpolation approximation may be required after the generation of the image. The same applies to transmission and reception using the spherical coordinate system. There is a report (Non-Patent Document 6) of a process that is performed with an approximation process when the transmission focus is performed, and similarly, the result is obtained in the polar coordinates (r, θ). The inventors of the present application have proposed a method of directly generating an image signal in a Cartesian coordinate system as a result of beam forming of transmission or reception in those polar coordinate systems, spherical coordinate systems, and arbitrary orthogonal curved coordinate systems (5). , (5-1), (5-1 '), and (5-2) have also been invented. In that case, the imaging of the transmission signal, the reflection signal, the scattering signal, the attenuation signal, and the like, the displacement measurement, and the like can be consistently performed in the same Cartesian coordinate system. In these, similarly to the method (1), the same processing can be performed in an arbitrary rectangular coordinate system or by converting to an arbitrary rectangular coordinate system. In addition, beamforming described in paragraphs 0209 to 0220 and the like of method (1) and paragraph 0238 and the like of method (2) can be performed in the same manner. It can be installed arbitrarily regardless of the shape (Patent Document 7, Non-Patent Document 8). Further, the present invention is not limited to this (hereinafter, the same). Further, although the deflection can be performed as described above, it is possible to process the case where the physical transmission beamforming and the soft reception beamforming have different deflection angles. It is also possible to softly perform transmission steering. In that case, the deflection angle may be different from other deflection angles. It is also possible to physically perform beamforming upon reception. Transmission and reception can be interpreted in reverse. It may be apodized at the time of transmission, or may be subjected to reception apodization processing on the received signal (hardware at the time of reception, or softly after reception). When performing apodization by software, it is performed according to the method (1) or the method (3). The apodization is performed in the same manner when the method of combining the beam forming of plane wave transmission and the receiving dynamic focusing of the method (2) or the method (3) is used.

  It should be noted that any processing of the method (4) using the method (1) of performing the plane wave processing can theoretically and practically perform arbitrary physical transmission or reception beamforming. By performing the processing as described above, various combinations of beamforming can be performed (for example, physical beamforming using a computer or a dedicated device, etc., which is different from that performed in soft beamforming using a computer or a dedicated device). It is possible to perform plane wave transmission and reception processing for each or both of those that involve processing such as focusing, steering, apodization, etc. that may be performed during transmission and reception, or, as described above, reverse transmission and reception. Can be processed by catching). For example, regarding simultaneous transmission of a plurality of beams as described in paragraphs 0107, 0110, 0363, 0365, 0366, etc., these beams may or may not interfere with each other with or without physical deflection. Including the case, or when performing their focus beamforming at different timings in the target simultaneous phase, or in the case where both received signals are mixed, physical focus (sub-aperture width, distance and depth, The same process (4) is effective regardless of whether the physical transmission deflection angles are the same or different, and in particular, (i A high frame rate is realized by using the method of performing the image signal generation processing once for the superposition of the received signals obtained in the effective aperture width. In the method (4), it is not always necessary to perform beamforming at a position where the waves do not interfere with each other (described in paragraphs 0030 and 0362), and even if the waves interfere, such as when overlapping sub-apertures are used at the same time. A high frame rate can be realized by processing. At this time, if the soft transmission deflection angle and the reception deflection angle applied to the plurality of focus beams to be implemented are the same, the above processing may be performed. In addition, even in the case of performing multiple times of focusing such as focusing at a plurality of positions or transmission dynamic focusing in the target simultaneous phase, the same processing can be performed for superimposing received signals. With respect to the received signal group received in the target simultaneous phase, if the received signals are in a state in which the times are aligned based on the position and timing of the transmission element, this processing can be performed on all of them.

  In addition, in the case where a soft deflection angle or a reception deflection angle to be applied to a plurality of focus beams is different, it is divided into the same ones, and the same processing is applied to each of the same ones to obtain the final result. It suffices to perform superposition in the frequency domain to obtain it. A plurality of deflected receive beams (including a deflection angle of 0 °) may be generated for one physical transmission beam (with or without deflection), and are similarly processed. Even when a plurality of different physical deflections are performed, they may be divided into the same one to obtain the respective processing results, or may be processed without being divided. When divided, superposition may be performed in the spatial domain or the frequency domain.

  When transmitting physically in multiple directions, software-specific transmission and reception deflection may be applied to each transmission deflection angle. In that case, should the transmission beams be separated in the frequency domain? , Or independent component analysis (as a reference, there are many references including Te-Won Lee, Independent Component Analysis: Theory and Applications, Springer, 1998 etc. which are relatively old books) May be processed. Analog devices may also be used. As an example, it is possible to set a soft transmission or reception deflection angle that is the same as each physical deflection angle. Signal separation is also described elsewhere (eg, paragraph 0368).

  Although it has been described here that the present method is performed for various fixed focusing processes, the present method is not limited to these, and can be used when other transmission beamforming is performed. Focusing (multi-focus that realizes multiple different focus positions with respect to the effective aperture) or not, deflection (multiple steerings with different deflection angles) or not, apodization (including different positions) Also, in the case of performing a plurality of transmissions or receptions with different wave or ultrasonic parameters such as none, F number, different transmission ultrasonic frequency or transmission band, different reception frequency or reception band, different pulse shape, different beam shape, etc. , Which can be processed in the same manner and which has a new feature that cannot be generated by one fixed beamforming. For example, it is known that a plurality of focuses can be obtained by superimposing and a wide band (high resolution) can be achieved in both the depth direction and the lateral direction, but these processes can be performed at high speed. When a so-called pulse inversion method (radiating pulses having different polarities as ultrasonic parameters) is used in order to obtain harmonics, received signals are superposed and similarly processed at high speed. Of course, it is also possible to superimpose received signals after performing beamforming. The received signals of two or more beams may be superposed.

  The above-mentioned processing may be applied to the simultaneous reception beamforming on the basis that the above-mentioned transmission and reception are considered in reverse. Further, the above processing may be applied to both transmission and reception.

  When the processing is divided into a plurality of beamformings, the processing may be performed in parallel. It may be divided into a plurality of beamformings depending on various waves such as the above-mentioned deflection angle, ultrasonic parameters, the position of the region of interest, and the like. For example, one received signal may be used for multiple purposes such as for imaging, measurement, and treatment, and a large amount of information, such as a transmitted signal, a reflected signal, a scattered signal, or an attenuated signal, which has high accuracy and high resolution, is beamed. There is a case where a signal that is generated by forming and is subjected to post-processing such as filtering is generated to meet a purpose, but appropriate beam forming is performed according to a purpose, and they may be processed in parallel.

In addition to arbitrary beams such as fixed focus beams, beamforming during transmission of arbitrary waves (including waves that have not been beamformed), superposition processing during transmission of multiple beams or waves, and simultaneous multiple beams It is possible to perform processing when transmitting waves or waves. In other words, reception beamforming (dynamic focusing, etc.) can be performed at one time regardless of any single or multiple transmissions. A plurality of beamformings may be performed by using the multi-directional aperture plane synthesis method, and in that case, the beamformings are similarly performed at high speed. The present invention is not limited to these.
Note that one of the features of the present invention is that the interpolation approximation processing is not performed in the wave number matching, but in the present method (4) applying the method described in the above methods (1) to (3). In the same manner as in methods (1) to (3), interpolation approximation processing may be performed in wave number matching, and approximate wave number matching described in them may be performed to perform high-speed beam forming. There is. In order to perform highly accurate approximate wave number matching, it is necessary to appropriately oversample the received signal at the cost of an increased calculation amount. In that case, it should be noted that the number of data of the Fourier transform is increased unlike the case where the signal at an arbitrary position can be selectively generated when the interpolation approximation process is not performed.

Method (5): Image signal generation in polar coordinate system In method (5), ultrasonic cylindrical waves (a part of) are transmitted or received in a two-dimensional polar coordinate system (r, θ) such as convex array, sector scan, IVUS, etc. This is a method of generating an image signal in the Cartesian coordinate system in the case (see FIG. 7). The methods (1) to (4) and (6) can be carried out.

The polar coordinate display of the Fourier transform will be described below. The two-dimensional Fourier transform is represented by equation (22).
Since the received echo signal in the polar coordinate system is represented by f (r, θ), the equation (23) is established.
Therefore, the expression (24) is obtained through the Jacobi operation. In this way, the waves represented in the polar coordinate system can be decomposed into plane wave components (k _x , k _y ) in the Cartesian coordinate system. Similarly, a wave represented in arbitrary rectangular coordinate can be decomposed into a plane wave component (k _x , k _y ) in the Cartesian coordinate system.

Method (5-1): Image Signal Generation for Cylindrical Wave Transmission or Reception FIG. 13 is a flowchart showing digital signal processing at the time of cylindrical wave transmission. From Equation (24), the Fourier transform in the angle θ direction on the aperture is represented by Equation (25).
Here, r ₀ is the radius of curvature of the convex probe, and x ₀ and y ₀ are the x-axis and y-axis coordinates representing the array element position of the convex probe. In step S21, the received signal is Fourier-transformed with respect to time t, and in step S22, the received signal is Fourier-transformed (FFT) with respect to the angle θ, so that the signal received in the polar coordinate system is converted into a plane wave component (k _x , can be decomposed into k _y ).

Therefore, for example, the image signal can be generated by subjecting this to the wave number matching represented by the equation (26) (step S23) and performing the inverse Fourier transform on the space (x, y).

Further, in step S24, the two-dimensional spectrum is multiplied by the following complex exponential function to calculate the angular spectrum at each depth y.
Alternatively, step 23 and step 24 may be performed in reverse.

Alternatively, without using the equations (26a) and (26b), according to the method (5), the following complex exponential function may be applied to perform the wave number matching and the angular spectrum at each depth position y may be obtained. good.

  Further, for example, in step S25, the frequency components k of the angular spectra are added together, and in step S26, the inverse Fourier transform (IFFT) is performed on the horizontal wave number kx, so that an image signal is obtained in step S27. A pure two-dimensional inverse Fourier transform may be performed.

  When steering is performed, according to the method (1), the wave number matching in the x direction and the y direction may be performed and the spatial resolution may be obtained according to the equations (9a) to (9c) using the deflection angle θ. As will be described later, when the calculation is performed in the polar coordinate system (r, θ), the steering angle (angle formed with the radial direction) can be provided in the polar coordinate system and steering can be performed in the same manner. Physical steering can be performed, soft steering for transmission or reception, or transmission / reception can be performed, or a combination of physical steering and soft steering can be performed. There are like other methods such as method (1).

  This method does not require interpolation processing for wave number matching and coordinate system conversion when obtaining an image signal of Cartesian coordinate system (x, y) from a signal of polar coordinate system (r, θ). Beam forming is performed. Similar to the plane wave transmission in the linear array type transducer, the cylindrical wave can be deflected in the polar coordinate system. The same processing can be performed when the steering angles of the transmit beam forming and the receive beam forming are different. You can also apply soft steering. Apodization can be performed similarly. In the case of a cylindrical wave, the above-mentioned transmission is simultaneously performed and received at different positions in the z-axis direction orthogonal to the two-dimensional polar coordinate system (that is, the z-axis in the cylindrical coordinate system (r, θ, z)). The above-mentioned processing may be performed by superimposing the received data by performing the above-mentioned transmission at different times, although it is a time phase. In the z-axis direction, it may be focused by an analog device (lens), and arbitrary processing can be performed by the digital signal processing of the present invention. The same calculation can be performed when the wave propagation direction is in the center direction (for example, useful for HIFU treatment, various imaging by a circular-based array transducer surrounding an object, CT, etc.). Of course, there may be reception-only beamforming in them, and they are similarly processed. The received signal represented by polar coordinates (r, θ) can be processed by replacing the Cartesian coordinates (x, y) in method (1) with polar coordinates (r, θ). , θ) can generate an image signal as described above, and interpolation approximation is performed in the subsequent processing. In these, steering can be performed similarly. The methods (2) to (4) and (6) can be similarly carried out.

  Further, when the received signal is represented as a digital signal of Cartesian coordinates (x, y), f (x, y) is Fourier-transformed with respect to the radius r and the angle θ, which is the opposite of the equation (22). After all, it is also possible to generate the image signal in the polar coordinate system (r, θ), or use each method to generate the image signal in the Cartesian coordinate system (x, y). Steering and apodization may occur as well.

  Further, as shown in FIGS. 8B (d) to 8 (f), the physical aperture element array represented by the polar coordinate system as described above or the physical aperture having an arbitrary aperture shape is used to transmit or receive at an arbitrary distance position. , Or both plane waves may be generated and beamforming may be performed in the same manner, and an image signal is generated in a Cartesian coordinate system or a polar coordinate system, or an orthogonal curved coordinate system set according to the physical aperture shape. Sometimes. It is equivalent to generating a virtual linear aperture array (or plane wave) at that distance position, and setting the distance position to zero corresponds to the case where the linear aperture array is virtually used. The distance positions can be set in front of the physical aperture as well as behind the physical aperture, and virtual linear aperture arrays (or plane waves) can be generated at those positions. The plane wave may be steered or the virtual linear aperture may be tilted (virtually mechanically steered). Of course, the physical aperture is mechanically steered if desired. When only those plane waves are transmitted or only received, other beamforming may be performed on the basis of the case of transmitting and receiving cylindrical waves, respectively.

Method (5-1 '): Image signal generation using virtual source and aperture array of other arbitrary shape When transmitting wave from arbitrary aperture shape such as linear array type transducer as well as circular aperture array, A case where a part of the cylindrical wave is generated using the installed virtual source (see FIGS. 8A (a) to 8 (c)) will be described.

  (I) When using the received signal acquired for monostatic aperture plane synthesis, a complex exponential function is added to Fourier transform for the received signal transmitted / received in each element and stored in the memory or the like. Multiply the response of the wave generated from the virtual source into a digital received signal represented by polar coordinates (r, θ), and then follow method (5) or use method (5-1) , Can directly generate an image signal in the (x, y) coordinate system. Similarly, the received signal can be represented as a digital signal with polar coordinates (r, θ), and the Cartesian coordinates (x, y) in method (1) can be replaced with polar coordinates (r, θ) to perform processing. It is also possible to generate an image signal at (r, θ). Of course, the monostatic processing of method (2) is also possible in the polar coordinate system (r, θ).

  (Ii) When using the received signals acquired for multi-static aperture plane synthesis, it is necessary to use the received signals transmitted by each element, received by surrounding elements, and stored in the memory. For example, the Fourier transform is multiplied by the complex exponential function, and the response of the wave generated from the virtual source is used as the digital received signal represented by polar coordinates (r, θ), and the multi-static aperture plane synthesis of method (3) is performed. it can. As another processing, according to the method (5), or by superimposing the digital received signals on each receiving element and then using the method (5-1), the (x, y) coordinate system is directly used. An image signal can be generated at. Similarly, it is also possible to superimpose the digital received signals on each receiving element and then perform the process of replacing the Cartesian coordinates (x, y) of method (1) with polar coordinates (r, θ). It is also possible to generate an image signal at (r, θ). Of course, the multistatic processing of the method (3) can also be performed in the polar coordinate system (r, θ) without overlapping.

  (Iii) In these processes, in order to omit the process of rewriting the signal received by the physical aperture array into the digital signal of the polar coordinate system (r, θ), the sampling is performed from the original in the polar coordinate system (r, θ). In some cases, a transmission or reception delay pattern is used to transmit and receive sampling from each aperture element. Then, the image signal can be directly generated in the (x, y) coordinate system based on the method (5-1) or the method (2) or the method (3) based on the method (5). Similarly, the received signal is represented as a digital signal with polar coordinates (r, θ), and the Cartesian coordinates (x, y) in methods (1) to (3) are replaced with polar coordinates (r, θ). It is also possible to generate an image signal in polar coordinates (r, θ).

  (iv) Similarly, when a part of the cylindrical wave is generated by using a virtual source installed in the rear in an arbitrary opening shape (see FIGS. 8A (a) to 8 (c)), (i) to (i) above. In iii), the Fourier transform of the received signal received by each element and stored in the memory or the like is multiplied by a complex exponential function to represent the received signal as a digital signal of Cartesian coordinates (x, y) (however, time is (Required) or interpolation approximation is performed, and conversely to the equation (22) in the method (5-1), f (x, y) is Fourier-transformed with respect to the radius r and the angle θ, and processed. It is also possible to generate the image signal in the system (r, θ), or use each method to generate the image signal in the Cartesian coordinate system (x, y). An image signal can be generated in the same manner even in an orthogonal curved coordinate system (curved coordinate system) set according to the opening shape.

  In addition to (i) to (iv), various beamforming and the like described in the method (5-1) can be performed.

  As described in the method (1) and the like, a virtual source (Fig. 8A (Fig. 8A (Fig. 8A ( When a cylindrical wave is transmitted (using a transmission delay) using (a) to (c)), each element is coded and transmitted as in the case of plane wave transmission, and the received reception is performed. By decoding the signals to generate a received signal group for aperture plane synthesis, the above process can directly generate an image signal in any Cartesian coordinate system such as Cartesian coordinate system or polar coordinate system. it can. In addition, a virtual receiver may be set instead of the virtual source, and the virtual receiver may double as a virtual source.

In addition, a virtual source (FIG. 8A (shown in FIG. 8A (Fig. 8A ( When a cylindrical wave is transmitted (using a transmission delay) using (a) to (c)), the following can be performed using the above method.
(A) The method (1) itself is directly applied to the received signal represented by the Cartesian coordinate system (x, y) obtained by the linear array transducer or mechanical scan, and imaged in the Cartesian coordinate system. Get the signal.
(B) The signal received at each receiving position by a linear array transducer or mechanical scan is multiplied by a complex exponential function to the frequency response obtained by the (fast) Fourier transform in the y direction, and spatially in the y direction. In the polar coordinate system (r, θ) that shifts and uses the virtual source as the origin, correct it to position coordinates in the radius r direction under θ determined by the receiving position, and apply method (5) or method (5-1). , An image signal is obtained in the Cartesian coordinate system (x, y) or the polar coordinate system (r, θ). Approximate spatial shifting by zero padding of signal values in the r coordinate system may be performed instead of spatial shifting using a complex exponential function, but to improve accuracy, appropriate oversampling It is necessary to take into account that a high sampling rate AD converter and many memories are required, and the number of data increases before Fourier transform.
(C) The method (5) or the method (5-1) is applied to a signal received in an arbitrary aperture shape different from the linear array transducer or the pseudo linear array aperture by the mechanical scanning, and the Cartesian method is similarly performed. An image signal can be similarly generated in the coordinate system (x, y), the polar coordinate system (r, θ), or the orthogonal curve coordinate system (curved coordinate system) set according to the aperture shape.
(D) A virtual receiver may be used instead of the virtual source, or the virtual receiver may double as a virtual source.

As a result of these methods (5-1 '), for example, by using another type of transducer or another mechanical scan, a convex type or sector type transducer as shown in FIG. The image signal when () is used can be generated in the Cartesian coordinate system (x, y), the polar coordinate system (r, θ), or the orthogonal curvilinear coordinate system (curved coordinate system) set according to the aperture shape. .
In addition, conversely, when a linear type transducer is virtually used by using a physically different type transducer (for example, FIGS. 8B (d) to (f) in the case of physically using a convex type transducer). ), When the virtual source or virtual receiver is at the position of the physical aperture or behind or in front of the physical aperture) in the same manner, the Cartesian coordinate system (x, y) or polar coordinate system (r, θ), and can be generated in an orthogonal curve coordinate system (curved coordinate system) set according to the opening shape.
As a special case, for example, when a linear array type transducer is physically used, a case where a cylindrical wave is generated by using a virtual source or a virtual receiver behind the physical aperture is applied, and a horizontal wave is generated at an arbitrary distance position. An image signal in the case of generating a plane wave spreading in a direction or a virtually linear array type transducer (FIG. 8B (g)) can also be generated.
In these, the transmitted or received wave generated may be steered or the aperture may be virtually tilted (virtually mechanically steered). Of course, the physical aperture is mechanically steered if desired.

Method (5-2): Image Signal Generation at Fixed Focus FIG. 14 is a schematic diagram of fixed focusing using a convex type array. Also in the convex array, fixed focusing can be performed as shown in FIG. Each of FIGS. 14A and 14B is a schematic view when the position of fixed focusing is equidistant from each effective aperture and when it is set to an arbitrary distance position from the convex type array, as an example. Similar to the case of the linear array type (method (4)), the image signal can be generated by the same calculation process as that of the cylindrical wave transmission. That is, there are the following three methods based on the processing of the method (1) or the method (3).
(I) Image signal generation processing is performed once for each of the received signals obtained in the effective aperture width.
(Ii) A so-called normal low-resolution image signal is generated using the reception signal for each transmission, and they are superimposed.
(Iii) Similar to the multi-static type aperture plane synthesis, those having the same transmission / reception positional relationship are set as a set to generate image signals and superpose them.
As described above, the image signal can be directly generated in the Cartesian coordinate system, but it is also possible that the method (4) is carried out using the coordinate axes of the polar coordinate system to generate the image signal in the polar coordinate system. Deflection and apodization can be carried out as well. The z-axis direction can be processed in the same manner as (5-1).

  When the received signal is represented as a digital signal of Cartesian coordinates (x, y), f (x, y) is Fourier-transformed with respect to the radius r and the angle θ, and finally processed in the polar coordinate system (r , θ), or each method can be used to generate an image signal in the Cartesian coordinate system (x, y). Steering, apodization, and z-axis processing may be performed in the same manner.

  Even when steering is performed, the wave number matching in the x direction and the y direction may be performed and the spatial resolution may be obtained according to the method (4). As will be described later, when the calculation is performed in the polar coordinate system (r, θ), the steering angle (angle formed with the radial direction) can be provided in the polar coordinate system and steering can be performed in the same manner. Physical steering can be performed, soft steering for transmission or reception, or transmission / reception can be performed, or a combination of physical steering and soft steering can be performed. There are like other methods such as method (1).

  When a virtual source or a virtual receiver is used, a virtual aperture is realized at the position or before or after using the physical aperture described in the method (5-1 '). Transmit fixed focusing can be performed. For example, a linear array transducer may be virtually realized. In addition, a transducer having an arbitrary aperture shape may be realized. The image signal is generated in a Cartesian coordinate system, a polar coordinate system, or an orthogonal curved coordinate system set according to the physical aperture shape. Physical steering can be performed, soft steering for transmission or reception, or transmission / reception can be performed, or a combination of physical steering and soft steering can be performed. There are like other methods such as method (1). In these, the transmitted or received wave generated may be steered or the aperture may be virtually tilted (virtually mechanically steered). Of course, the physical aperture is mechanically steered if desired.

  As described above, the beam forming of the methods (1) to (4) can be performed, but the present invention is not limited to them, and the same effect can be obtained by adapting to any beam forming. In particular, when the method (4) is used, reception beamforming can be performed on any transmission beam or wave in addition to the transmission fixed focus beam. Needless to say, the beam forming of a batch reception signal at the time of simultaneous transmission of a plurality of different beams or waves or superposition of reception signals for each transmission can be similarly performed.

Method (5-3): Image signal generation at the time of reception in a spherical coordinate system When a spherical nucleus-shaped wave aperture element array is used, three-dimensional digital wave signal processing is performed. If the element array is so, the reception of the wave is performed in the spherical coordinate system (r, θ, φ ), so the received signal of the wave received is represented as f (r, θ, φ ). Also in this case, various beamforming can be performed through the Jacobi calculation as in the case of the two-dimensional polar coordinate system (r, θ).

Specifically, the three-dimensional Fourier transform performed on the received signal f (r, θ, φ ) in order to decompose the received wave into a plane wave in the Cartesian coordinate system (x, y, z) causes the Cartesian coordinate system ( x, y, wavenumber or frequency domain of _{z) (k x, k y} , represented by formula k _z) to (27), x = rsinθcos φ , y = rcosθ, and, with z = rsinθsin φ The image signal can be directly generated in the Cartesian coordinate system without performing the interpolation approximation processing by performing the calculation according to the equation (28) by the Jacobi calculation. Of course, the beamformings of the methods (1) to (4) and (6) can be performed, but the present invention is not limited to them, and the same effect can be obtained by adapting and using any beamforming. In particular, when the method (4) is used, similarly to the two-dimensional case, reception beamforming can be performed on all transmission beams or waves in addition to the transmission fixed focus beam. Of course, the beam forming of the batch reception signal at the time of simultaneous transmission of a plurality of different beams or waves or the superposition of reception signals for each transmission can be similarly performed. In addition, when using a virtual source or a virtual receiver, or when performing steering, all can be performed in the same manner as in the two-dimensional case, according to the Cartesian coordinate system or the spherical coordinate system, or the physical aperture shape. An image signal can be generated in the set orthogonal curved coordinate system.

Method (5 "): Image signal generation in arbitrary orthogonal curve coordinate system when transmitting or receiving in Cartesian coordinate system Inversely to the above series of methods, reception obtained by performing transmission or reception in Cartesian coordinate system An image signal represented by a two-dimensional polar coordinate system or a spherical coordinate system can be directly obtained from the signal without performing interpolation approximation, and can be realized by the same calculation, for example, when the received signal is f (x, y, z), the Fourier transform in the r , θ , and φ directions is performed , and the received signal is decomposed into a circular wave or a spherical wave corresponding to a plane wave in the Cartesian coordinate system through the Jacobian operation. These methods may also be used to vary the FOV (eg, may be wider), using the Jacobi operation to generate image signals in any Cartesian coordinate system as well. It is also possible to generate an image signal in any Cartesian coordinate system when transmitting or receiving in any coordinate system, as in any other method described in the method (5). And waves can be processed, steering can be performed as well, and virtual sources and receivers can be used.

  Note that one of the features of the method (5) is that beam forming is performed in an arbitrary coordinate system without performing interpolation approximation processing in wave number matching. However, the method (1) is applied by applying the method (1). -When performing the beam forming described in the method (4), the method (6), and the method (7) in an arbitrary coordinate system, interpolation approximation processing may be performed in wave number matching, which is described in each of them. Approximate wave number matching may be performed and beam forming may be performed at high speed. In order to perform highly accurate approximate wave number matching, it is necessary to appropriately oversample the received signal at the cost of an increased calculation amount. In that case, it should be noted that the number of data of the Fourier transform is increased unlike the case where the signal at an arbitrary position can be selectively generated when the interpolation approximation process is not performed.

Method (6): Migration method In the apparatus of the present invention, it is possible to perform the migration processing without performing the interpolation approximation processing in the wave number matching. The migration equation (the following equation (M6 ′)) itself is well known, and the derivation of the equation is also well known, so the derivation of the equation will be omitted here.

  Non-Patent Document 12 describes a normal migration process based on one-element reception by one-element transmission (that is, corresponds to a non-deflecting process using transmission / reception data for monostatic aperture plane synthesis of method (2)). As a basis, in the case of plane wave transmission and / or reception with and without steering (processing corresponding to method (1)), a wave is generated from any transmission aperture element for any one of the same positions. Since the propagation time, which is the time until the wave is received by the reception aperture element that also serves as the transmission aperture element, is different from that in the case of the normal migration, the propagation velocity and the coordinates of the target position are reread (the following formula (M1 )), The method of calculating the value represented by the same form (Formula (M6)) is disclosed.

  However, the processes of the other methods (2) to (5) are not disclosed in Non-Patent Document 12 (when steering is performed in the method (2), they are not disclosed). Further, in calculating the formula (M6 ′), conventionally, interpolation approximation has been performed when performing wave number matching (formulas (M4) and (M4 ′)), but in the device of the present invention, Wave number matching is performed with high accuracy without performing interpolation approximation (formula (M7) and formula (M7 ′)).

Two-dimensional coordinates are taken with the x-axis in the horizontal direction and the y-axis in the depth direction, and the time coordinate is t. Specifically, in the normal migration, the propagation time required for the wave to travel back and forth between the arbitrary aperture element position (x, 0) and the arbitrary position (x _s , y _s ) is expressed by the equation (M0). To be done.

On the other hand, in the plane wave transmission with the steering angle θ (including 0 °), the propagation time is represented by the formula (M0 ′).

Therefore, in the calculation performed based on the migration method when transmitting the deflected plane wave of the method (1), each of the carrying speed c and the coordinate system (x _s , y _s ) representing the position of the target is replaced with the expression (M1). A normal migration formula is calculated (formula (M4) and formula (M5)).

  In summary, among the methods (1) to (5), migration is performed in the same manner except for the normal migration in which the non-biasing process using the transmission / reception data for monostatic aperture plane synthesis of the method (2) is performed. It can be processed. For example, the calculation procedure of migration when transmitting a polarized plane wave (including 0 °) in the method (1) will be mainly described.

  FIG. 15 is a flowchart showing a migration process when a polarized plane wave is transmitted. When the received signal is represented as r (x, y, t), the received signal at the aperture element array position is represented as r (x, y = 0, t).

First, as shown in equation (M2), the received signal is subjected to a two-dimensional Fourier transform with respect to time t and horizontal direction x (two-dimensional fast Fourier transform is preferable).
Here, k = ω / c, the wave number k and the angular frequency (angular frequency) ω are related by the proportional constant 1 / c, and there is a one-to-one correspondence, and ω is used instead of k Can be calculated.

  As described above, a special two-dimensional fast Fourier transform method can be used, but a general method is as follows. First, in step S31, the received signal is detected at the time t at the horizontal coordinate x. Fast Fourier Transform (FFT) is performed to obtain the spectrum of the analytic signal. Then, at each frequency coordinate within the band k, the fast Fourier transform in the horizontal direction x may be performed (faster than calculating each of the two-dimensional spectra according to the equation (M2)).

If the plane wave is not deflected and transmitted, the above calculation is sufficient. However, if the plane wave is deflected, trimming must be performed. For that purpose, in step S32, for the trimming, the fast Fourier transform for the time t is performed. Multiply the transformed R '(x, 0, k) by the complex exponential function (M3) (similar to the complex exponential function (11) in method (1), Operations can be calculated directly at once, or a dedicated Fast Fourier Transform that allows such calculations is also useful).

Then, in step S33, the received signal is subjected to fast Fourier transform (FFT) in the horizontal direction x. The result will be represented as R ″ (k _x , 0, k) here. By the way, even if it is programmed to perform trimming, it is possible to process the case of transmitting a plane wave without steering (steering angle 0 °).

Usually, wave number matching (or mapping) is then performed. When the beamforming is a method (1) to (5) other than the normal migration (when there is no steering in the method (2)), the propagation velocity c and the coordinate system (x _s , y _s ) are calculated by the above equation. As in (M1), the processing is performed by replacing the propagation velocity (E1) and the coordinate system (E2) for each beamforming.

For the two-dimensional Fourier transform R ″ (k _x , 0, k) calculated in the case of the method (including the method (1)) other than the normal migration (when there is no steering of the method (2)), Or, for the above R (k _x , 0, k) calculated in normal migration, through interpolation approximation (using bi-linear interpolation using the angular spectrum closest to the frequency coordinate, etc.) , And the wave number matching represented by the formula (M4) or the formula (M4 ′) is performed, respectively.
However, s = 2 when the received signal is a reflected signal, and s = 1 when it is a transmitted signal.
However, when the interpolation approximation is not performed in the wave number matching of the equations (M4) and (M4 ′), the wave number in the depth direction represented by the proviso in each equation is used. The wave number in each depth direction is obtained by dividing the angular frequency ω by the propagation velocity c by the equation (E1). The same applies hereinafter.

By performing wave number matching in this way, the following function (M4 ″) is obtained.
Further, the following formula (M5) or formula (M5 ′) is obtained using the function (M4 ″).

An image is obtained by performing a two-dimensional inverse Fourier transform on the wave number k _x and the wave number (E3) on the expression (M5) or (M5 ′) as represented by the expression (M6) or the expression (M6 ′). The signal f (x, y) is generated.
The two-dimensional inverse Fourier transform in the calculation of the equations (M6) and (M6 ′) may be performed by the fast two-dimensional inverse Fourier transform (IFFT), and a special fast two-dimensional inverse Fourier transform can be used. As a general method, in each of the equations (M6) and (M6 ′), first, a fast inverse Fourier transform is performed for one wave number k _x in the signal band with respect to the other wave number (E3). Then, the fast inverse Fourier transform with respect to the wave number k _x (within the signal band) may be performed on each coordinate of the generated spatial coordinates y (each of the two-dimensional image signals is expressed by the formula (M6) or It is faster than calculating according to equation (M6 ')).

Non-Patent Document 12 does not disclose the formula (M6) using y _S in the formula, and discloses that y is used instead of y _S for calculation, and the coordinates are corrected after the calculation. .. The correction of the coordinates is performed without approximation by performing approximation processing or by taking time based on multiplication of a complex exponential function, which is a past invention of the inventor of the present application. Formula (M6) can be used even when the deflection angle is 0 °.

In the apparatus of the present invention, the wave number matching is performed with the two-dimensional inverse Fourier transform or with the depth-direction inverse Fourier transform without performing interpolation approximation. That is, the two-dimensional Fourier transform R ″ (k _x , 0, k) calculated in the case of a method (including method (1)) other than the normal migration method (when steering is not included in method (2)) On the other hand, or for the above R (k _x , 0, k) calculated in the normal migration method, as represented by the formula (M7) or the formula (M7 ′), first, The integration with respect to k is performed for each k _x , the wave number matching of the wave number (E3) in the depth direction and the inverse Fourier transform (IFFT) are performed at the same time (step S34), and then, in the lateral (x) direction. Performs a fast inverse Fourier transform.
Non-Patent Document 12 does not disclose the formula (M7) using y _S in the formula. Formula (M7) can also be used when the deflection angle is 0 °. Similar to the methods (1) to (6), the frequency k components of the spectrum are added together, and then the inverse Fourier transform (IFFT) regarding the wave number k _x in the lateral direction is performed, and the calculation can be performed by one inverse Fourier transform. The calculation is fast.

Further, if the migration is different from the normal migration (processing corresponding to the method (2) without steering), correction of the position in the lateral (x) direction is performed in the process of calculating the formula (M6) and the formula (M7). It can be performed. For example, when the polarized plane wave of the method (1) is transmitted, first, in step S34, the wave number (E3) is calculated as described above, and in step S35, each result is obtained for position correction. The function (M8) is multiplied by the complex exponential function (M9), and then, in step S36, the fast inverse Fourier transform (IFFT) is performed on the transverse wave number k _x . Alternatively, it may be calculated by multiplying by the formula (M9) together with the complex exponential function of the inverse Fourier transform related to the wave number k _{x in the} horizontal direction, or the dedicated inverse fast Fourier transform may be carried out. Formula (M9) can be used even when the deflection angle is 0 °. As described above, the image signal f (x, y) is generated in step S37.
In summary, a new process can be performed by using the formula (M6), the formula (M7), or the formula (M7 ′), and the image signal f (x, y can be processed at high speed without error due to interpolation approximation. ) Can be generated.

If the same result is obtained without multiplying the formula (M9) without the approximation process, the formula (M6) or the formula (M7) is calculated by using the following formula (N4) instead of the formula (M4). good.
That is, in the wave number matching, when interpolation approximation is not performed, the wave number in the depth direction represented by the proviso in the equation is used. It is divided by the speed (E1).
The equation of the wave number in the depth direction expressed in this equation is similar to the equation (13) in the method (1), but in the method (1), kx in the equations (13) to (15) is used. When the same result is obtained when (-zero) is used without using -ksinθ of -ksinθ, paragraph 0202 or paragraph 0202 or Equation (16) may be multiplied by equation (M9) before performing the processing described in 0203. However, the deflection of the plane wave realized by the method (6) is realized only by approximation calculation. Therefore, when the equation (N4) and the equation (M7) are used in the method (6), Is highly accurate without any approximation processing, but the accuracy is reduced by using the formula (M9) in the method (1). Further, when the final inverse Fourier transform is performed by the two-dimensional fast inverse Fourier transform (as will be described later, the three-dimensional fast inverse Fourier transform in the case of three-dimensional), if these processes are performed, the calculation speed becomes Method (6) speeds up, but method (1) slows down (the processing described in paragraph 0203 is high speed).
Further, in each of these modified methods (1) and (6), when performing interpolation approximation processing in wave number matching and obtaining the same result using equations (M9) and (N4), , The equation of the interpolation approximation changes correspondingly (described in paragraphs (352) and (B)).
Further, in each of these modified methods (1) and (6), when the interpolation approximation processing is performed in wave number matching, the above equations (11) and (M3) are used (deflection angle data θ , And the case where the formulas (11) and (M3) are not used (deflection angle θ is set to zero), the formula of interpolation approximation changes correspondingly (when not used). Is described in paragraphs (352) (A ′) and (B ′)).
Beamforming using plane wave transmission has various beamforming applications, as described herein, but in those applications, the processes described in this paragraph may be used instead. It should be noted that, when receiving dynamic focusing is performed on an object subjected to arbitrary transmission beamforming such as transmission focusing by applying the method (6), the angular frequency ω is Since (M3 ″) represented by using the wave number [Equation (M13)] represented by and the converted propagation velocity (E1) is used instead of Equation (M3), -ksinθ in the interpolation approximation expression is used. _For wave number k of _t , it is necessary to use the equation (M13) instead.
In each of the method (1) and the method (6), the methods described in this paragraph may be combined and performed. For example, similar to the method of J.-y. Lu et al. (See paragraph 0195, the formula is described in paragraph (C ′) of paragraph 0352) of performing interpolation approximation in the method (1), the wave number matching is performed in the method (6). Is performed through interpolation approximation, and the first two-dimensional Fourier transform and the last two-dimensional inverse Fourier transform can be performed by the fast two-dimensional Fourier transform (described in paragraph 0352 (D ′). 3D fast Fourier transform in the case of 3D). In each of these, there are cases where the formula (11) is used (deflection angle data θ is used) and the formula (M3) is used (described in paragraphs (C) and (D) of paragraph 0352). Of course, it can also be used when there is no deflection.
As described above, the plane wave transmission based on the method (1) and the method (6) is applied to various beam forming.

  Here, the migration method is mainly used to perform the beam forming at the time of transmitting the plane wave with and without the steering in the method (1) at high speed without interpolation approximation in the wave number matching. Method (2) (monostatic aperture plane synthesis method including steering), method (3) (multistatic method with or without steering), method (4) (transmission fixed focus with or without steering), and All beamformings described in each of the methods (5) (beamforming in polar coordinate system or arbitrary orthogonal curvilinear coordinate system) can be similarly performed. The same processing can be performed when the deflection angle is different between transmission and reception. Apodization may occur as well.

  A three-dimensional case can be processed similarly. When the received signal obtained using the two-dimensional aperture element array is expressed as r (x, y, z, t), the received signal at the aperture element array position (y = 0) is r (x, y = It is expressed as 0, z, t).

First, as shown in Expression (M′2), the received signal is subjected to three-dimensional Fourier transform with respect to time t, horizontal direction x, and elevation direction z (three-dimensional fast Fourier transform is preferable).
Here, k = ω / c.

Generally, the received signal is subjected to fast Fourier transform (FFT) with respect to time t at each position coordinate (x, 0, z) to obtain the spectrum R (x, 0, z, k) of the analytic signal. Be done. Then, at each frequency coordinate within the band k, the fast Fourier transform in the horizontal direction x and the elevation direction z is performed to obtain R (k _x , 0, k _z , k) (of the three-dimensional spectrum It is faster than computing each according to equation (M'2)).

If when the plane wave is not deflected transmitting is good in the above calculations, the deflection angle of zero degree or non zero formed by the direction and the axial direction to be transmitted as a plane wave represented using elevation θ and azimuth angle φ Must be trimmed, for which R ′ (x, 0, z, k) after fast Fourier transform with respect to time t is multiplied by a complex exponential function (M′3) (fast Fourier with respect to time t). The transform and the multiplication of the complex exponential function can be calculated directly at once, or a dedicated Fast Fourier Transform capable of such calculation is also useful).

Then, the received signal is subjected to a fast Fourier transform (FFT) in the horizontal direction x. The result is R ″ (k _x , 0, z, k). By the way, even if it is programmed to perform trimming, it is possible to process the case of transmitting a plane wave without steering (steering angle 0 °).

Next, wave number matching (or mapping) is performed. In the case of methods (1) to (5) other than the normal migration (when there is no steering in the method (2)), beamforming is performed by using the propagation velocity c and the coordinate system (x _s , y _s , z _s ). The propagation velocity (E′1) and the coordinate system (E′2) for each beamforming are read as the processing.

For the three-dimensional Fourier transform R ″ (k _x , 0, z, k) calculated in the case of methods (including method (1)) other than normal migration (when steering is not included in method (2)) Or, for the above R (k _x , 0, z, k) calculated in normal migration, interpolation approximation (using the angular spectrum closest to the frequency coordinate, bi-linear) The wave number matching represented by the formula (M′4) or the formula (M′4 ′) is performed through interpolation, etc., respectively.
However, s = 2 when the received signal is a reflected signal, and s = 1 when it is a transmitted signal.
However, when interpolation approximation is not performed in the wave number matching of the equations (M′4) and (M′4 ′), the wave numbers in the depth direction represented by the proviso in each equation are used, but the interpolation approximation is performed. Each wave number in the depth direction in the case of performing is obtained by dividing the angular frequency ω by the propagation velocity c by the equation (E′1). The same applies hereinafter.

By performing wave number matching in this way, the following function (M'4 '') is obtained.
Further, the following formula (M'5) or formula (M'5 ') is obtained using the function (M'4'').

For the formula (M'5) or (M'5 '), as represented by the formula (M'6) or the formula (M'6'), the wavenumbers k _x and k _{z in} the three-dimensional case An image signal f (x, y, z) is generated by performing a three-dimensional inverse Fourier transform on the wave number (E'3).

For the three-dimensional inverse Fourier transform in the calculation of the formula (M'6) and the formula (M'6 '), a fast three-dimensional inverse Fourier transform (IFFT) may be applied, and a special fast three-dimensional inverse Fourier transform should be used. However, as a popular method, in each of the formulas (M′6) and (M′6 ′), first, for two wave numbers k _x and k _z in the signal band, A fast inverse Fourier transform for the other wave number (E′3) is performed, and then, for each coordinate of the generated spatial coordinates y, a fast inverse Fourier transform for the wave numbers k _x and k _z (in the signal band) is performed. (It is faster than calculating each of the three-dimensional image signals according to the formula (M′6) or the formula (M′6 ′)).

In the device of the present invention, the wave number matching is performed with the three-dimensional inverse Fourier transform or with the depth-direction inverse Fourier transform without performing interpolation approximation. That is, the three-dimensional Fourier transform R ″ (k _x , 0, k _z , calculated in the case of a method (including method (1)) other than the normal migration method (when steering is not included in method (2)) k) or the above R (k _x , 0, k _z , k) calculated in the usual migration method, expressed by the formula (M'7) or the formula (M'7 '). As described above, first, the integration with respect to k is performed for each (k _x , k _z ) in the band, and the wave number matching of the wave number (E′3) in the depth direction and the inverse Fourier transform (IFFT) are performed. Simultaneously, and thereafter, fast inverse Fourier transforms in the lateral (x) direction and the elevation (z) direction are performed.

Non-Patent Document 12 does not disclose the formulas (M′6) and (M′7) using y _S in the formulas. Both equations can be used even when the deflection angle is 0 °. Similar to the methods (1) to (6), the frequency k components of the spectrum are added together, and then the inverse Fourier transform (IFFT) is performed on the wave numbers k _x and k _z in the lateral direction and the elevation direction, and the inverse of one degree is performed. It can be calculated by Fourier transform, and the calculation is fast.

Further, when the migration is different from the normal migration (the processing corresponding to the method (2) without steering), in the process of calculating the formula (M′6) or the formula (M′7), the lateral (x) direction And the position in the elevation direction (z) can be corrected. For example, when the polarized plane wave of the method (1) is transmitted, first, as described above, the calculation regarding the wave number (E′3) is performed, and the function (M′8) obtained as each result for the position correction is calculated. Is multiplied by a complex exponential function, and then a fast inverse Fourier transform (IFFT) is performed on the wave numbers k _x and k _{z in} the lateral direction and the elevation direction.
In summary, a new process can be performed using the formula (M'6), the formula (M'6 '), the formula (M'7), or the formula (M'7'). The image signal f (x, y, z) can be generated at high speed without error.

When the same result is obtained without multiplying the complex exponential function corresponding to the equation (M9) in the two-dimensional case without the approximation process, the following equation (N'4) is used instead of the equation (M'4). Equation (M6) or Equation (M7) may be calculated using.
That is, in the wave number matching, when interpolation approximation is not performed, the wave number in the depth direction represented by the proviso in the equation is used, but the wave number in the depth direction when performing the interpolation approximation propagates the angular frequency ω. It is divided by the speed (E'1).
The equation of the wave number in the depth direction represented in this equation is similar to the equation (C22) in the method (1), but in the method (1), kx in the equation (C22) and the equation (C23) is used. without using the -Ksinshitacos phi and -Ksinshitasin phi of -Ksinshitacos phi and kz-ksinθsin φ (as zero) in the case of obtaining the same result when calculation method of the two-dimensional case (6) the formula (M9) As in the case of performing the inverse Fourier transform by multiplying by the complex exponential function corresponding to, the multiplication may be performed during the processing described in paragraph 0205. However, the deflection of the plane wave realized by the method (6) is realized only by approximation calculation. Therefore, as in the two-dimensional case, the equation (N′4) in the method (6) is used. When using the formula (M7) and the formula (M7), the accuracy is improved without any approximation processing. However, when the complex exponential function corresponding to the formula (M9) in the two-dimensional case is used in the method (1), the accuracy is improved. descend. In addition, when the final inverse Fourier transform is performed by the three-dimensional fast inverse Fourier transform, the processing speed is increased by the method (6) as in the two-dimensional case, if the processes are performed. , Method (1) is slower (the processing described in paragraph 0203 is faster).
Further, in each of these modified methods (1) and (6), when performing the interpolation approximation processing in the wave number matching, the complex exponential function and the expression (N) corresponding to the expression (M9) in the case of two dimensions are used. When the same result is obtained by using '4), the equation of the interpolation approximation changes correspondingly as in the two-dimensional case (described in paragraphs (352) and (B)).
Further, in each of these modified methods (1) and (6), when the above-mentioned formulas (C21) and (M'3) are used in the case of performing interpolation approximation processing in wave number matching (deflection angle In the case of using the data θ and φ ) and the case of not using the equations (C21) and (M′3) (setting all the deflection angles θ and φ to be zero), the case of two-dimensional Similarly, the equation of the interpolation approximation changes correspondingly (when not used, it is described in each of paragraphs (A ') and (B') in paragraph 0352).
Beamforming using plane wave transmission has various beamforming applications, as described herein, but in those applications, the processes described in this paragraph may be used instead. As in the case of the two-dimensional case, it should be noted that in the case where the receiving dynamic focusing is performed on an object subjected to arbitrary transmission beamforming such as transmission focusing by applying the method (6). As will be described later, (M′3 ″) represented by using the wave number [Equation (M′13)] represented by using the angular frequency ω and the converted propagation velocity (E′1) is represented by the equation (M Since it is used instead of '3), for the wave number k of -ksin θ ₁ (cos φ ₁ x + sin φ ₁ z) in the interpolation approximation formula, it is necessary to use the formula (M'13) instead.
In each of the method (1) and the method (6), the methods described in this paragraph may be combined and performed. For example, similar to the method of J.-y. Lu et al. (See paragraph 0195, the formula is described in paragraph (C ′) of paragraph 0352) of performing interpolation approximation in the method (1), the wave number matching is performed in the method (6). Can be performed through interpolation approximation, and the first three-dimensional Fourier transform and the final three-dimensional inverse Fourier transform can be performed by the fast Fourier transform (described in paragraph 0352 (D ′)). In each of these, there are cases where the formula (C21) is used (deflection angle data θ is used) and the formula (M′3) is used (described in paragraphs (C ′) and (D ′) of paragraph 0352). . Of course, it can also be used when there is no deflection.
As described above, the plane wave transmission based on the method (1) and the method (6) is applied to various beam forming.

  Also in this migration method, similarly to the methods (2) and (3), monostatic or multistatic aperture plane synthesis can be performed without performing interpolation approximation processing in wave number matching.

In the case of the monostatic aperture plane synthesis, when the soft transmission deflection angle and the reception angle are represented by θt and θr, the ultrasonic angular frequency ω ₀ and the propagation velocity c are used instead of the formula (M3). Wave number
Represented by
In the same manner, and in the case where the interpolation processing is not required in the wave number matching of the normal migration processing,
However, s = 2 when the received signal is a reflected signal, and s = 1 when it is a transmitted signal.
It should be done.

Further, in the three-dimensional case, it is assumed that each of the deflection angles of the transmission beam and the reception beam is expressed by using (elevation angle, azimuth angle) = (θ _t , φ _t ) and (θ _r , φ _r ). , The wave number matching is performed in the lateral direction first by multiplying by the complex exponential function (equation (D41)) represented by using the carrier frequency ω ₀ of the ultrasonic signal, as in the method (2). Regarding the direction, in order to have a resolution in the depth y direction, the complex exponential function (equation (D42)) excluding the lateral matching processing (equation (D41)) is multiplied, and at the same time, the complex exponential function (equation (D43) )) Is done. That is, the formula (D41) is used instead of the formula (M3 ′) in the case of two dimensions, and the product of the formula (D42) and the formula (D43) is used instead of the formula (M11).

  As described above, the migration process in the present invention corresponding to the method (2) and the method (3) based on the method (2) is equivalent to the methods (2) and (3).

Also in these cases, it is possible to perform interpolation processing in wave number matching to perform fast inverse Fourier transform in the same manner as in normal migration processing. In that case, method (2) and a method (based on this) 3) is not equivalent, and after the above-mentioned processing using the equation (M3 ′) and the like, instead of the equation (M4 ′) which is wave number matching with interpolation processing, based on the equation (M11),
However, s = 2 when the received signal is a reflected signal, and s = 1 when it is a transmitted signal. When interpolation approximation is not performed in wave number matching, the wave number in the depth direction represented by the proviso in the equation is used, but the wave number in the depth direction when interpolation approximation is performed It is divided by c. The same applies hereinafter.
Whether to implement the two-dimensional inverse Fourier transform [Equation (M6 ′)] of Equation (M5 ′) represented by using the same ky of (M4 ′ ″) , Or instead of the formula (M4 ′),
However, s = 2 when the received signal is a reflected signal, and s = 1 when it is a transmitted signal. When interpolation approximation is not performed in wave number matching, the wave number in the depth direction represented by the proviso in the equation is used, but the wave number in the depth direction when interpolation approximation is performed It is divided by c. The same applies hereinafter.
The equation (M4 ″) is obtained by performing wave number matching involving the interpolation processing represented by, and the equation (M5 ′) represented using the same ky of (M4 ″ ″)
A two-dimensional inverse Fourier transform [corresponding to the equation (M6 ′)] of the product obtained by multiplying by is executed.

  Also in this case, the multistatic aperture plane synthesis is performed in exactly the same manner as the method (3) is realized by applying the method (2), and the monostatic method using the migration method is used instead of the method (2). It can be realized by applying the aperture plane synthesis method.

A three-dimensional case can be processed similarly. That is, after the processing using the equation (M′3 ′) in the case of three dimensions and the like, the equation (D42) and the equation (D42) and the equation ( Based on the product of D43) [corresponding to (M11) in two dimensions],
However, s = 2 when the received signal is a reflected signal, and s = 1 when it is a transmitted signal. When interpolation approximation is not performed in wave number matching, the wave number in the depth direction represented by the proviso in the equation is used, but the wave number in the depth direction when interpolation approximation is performed It is divided by c. The same applies hereinafter.
The equation (M'4 '') represented by the following equation is obtained, and the three-dimensional inverse Fourier transform of the equation (M'5 ') represented by the same ky of (M'4''') [the equation (M ' 6 ')], or instead of formula (M'4'),
However, s = 2 when the received signal is a reflected signal, and s = 1 when it is a transmitted signal. When interpolation approximation is not performed in wave number matching, the wave number in the depth direction represented by the proviso in the equation is used, but the wave number in the depth direction when interpolation approximation is performed It is divided by c. The same applies hereinafter.
The equation (M'4 '') is obtained by performing wave number matching involving the interpolation process represented by, and the equation (M'5 ') represented by the same ky of (M'4'''') is obtained. ),
The three-dimensional inverse Fourier transform [corresponding to the equation (M′6 ′)] of the product obtained by multiplying by is executed.

  Also in this case, the multi-static aperture plane synthesis is performed in exactly the same way as when the method (3) is realized by applying the method (2), and instead of the method (2), a monostatic aperture plane by the migration method is used. It can be realized by applying a synthetic method.

  Based on these migration methods, all the beamformings described in the methods (2) and (3) can be similarly performed.

  Further, by using the migration process [equation (M7), etc.] at the time of transmitting the plane wave corresponding to the method (1), any beam such as the fixed focus beam of the method (4) can be used without performing interpolation approximation in the wave number matching. In addition, you can perform beamforming when transmitting arbitrary waves (including waves that have not been beamformed), superposition processing when transmitting multiple beams or waves, and processing when transmitting multiple beams or waves at the same time. . The plurality of beam forming operations may be performed by using the multi-directional aperture plane synthesis method, and in that case as well, it is similarly performed at high speed. Nor are they limited. In those cases, as in the case of using the method (1), as a combination with the method (2), the deflection dynamic focusing of reception can be performed for arbitrary transmission beamforming.

When the physical transmission deflection angle of the focus beam is A and the soft transmission deflection angle and the reception angle are θ (= θt) and θr, respectively, the angular frequency ω is given instead of the equation (M3). Wave number expressed using reduced propagation velocity (E1)
Represented by
Is also used, and when the physical transmission deflection angle of the plane wave is A and the soft transmission deflection angle and the reception angle are θ (= θt) and θr, respectively, instead of the formula (M3), To
Is similarly used, and in the formula (M7),
It should be done.

Also, the same processing can be performed in the case of three dimensions. When the physical transmission deflection angle of the focus beam is represented by the elevation angle A and the azimuth angle B (including the case where at least one of the angles is zero degree), the soft transmission deflection angle (elevation angle θ ₁ and When steering is performed at azimuth angle φ _{1 and} steering dynamic focusing is performed at deflection angles (elevation angle θ ₂ , azimuth angle φ ₂ ) (including the case where at least one of the angles is zero degrees), the formula (M Wave number expressed using angular frequency ω and reduced propagation velocity (E'1) instead of '3)
Represented by
Is used similarly, and when the physical transmission deflection angle of the plane wave is represented by the elevation angle A and the azimuth angle B (including the case where at least one of the angles is zero degree), the soft transmission deflection angle Steering at (elevation angle θ ₁ and azimuth angle φ ₁ ) and steering dynamic focusing at deflection angle (elevation angle θ ₂ , azimuth angle φ ₂ ) (including the case where at least one of the angles is zero degrees) ), Instead of formula (M′3),
Is similarly used, and in the formula (M′7),
It should be done.

Also in this case, it is possible to perform the interpolation processing in the wave number matching to perform the fast inverse Fourier transform as in the case of the normal migration processing. In that case,
Instead of equation (M4), which is wave number matching with interpolation processing, based on equation (M11 ′ ″),
However, when interpolation approximation is not performed in wave number matching, the wave number in the depth direction represented by the proviso in the equation is used. It is divided by the speed (E1). The same applies hereinafter.
Is the expression (M4 ″) represented by the above expression obtained, and the two-dimensional inverse Fourier transform [Expression (M6)] of the expression (M5) represented by the same ky of (M4 ′ ″ ″)? , Or instead of formula (M4),
However, when interpolation approximation is not performed in wave number matching, the wave number in the depth direction represented by the proviso in the equation is used. It is divided by the speed (E1). The same applies hereinafter.
The equation (M4 '') is obtained by performing wave number matching involving the interpolation processing represented by, and the equation (M5) represented by using the same ky of (M4 '''''')
A two-dimensional inverse Fourier transform [corresponding to the equation (M6)] of the product obtained by multiplying by is executed.

In the above, if the equations (M3 ″) and (M3 ′ ″) are interchanged and processed, an error occurs that the imaging position shifts when soft transmission steering is performed (when θt is non-zero). Cause Further, in these processes, the wave number represented by using the ultrasonic angular frequency ω ₀ and the converted propagation velocity (E1) instead of the formula (M10) which is the wave number corresponding to the ultrasonic frequency.
When using soft reception steering (when θr is non-zero), the generated deflection angle is larger than that when the equation (M10) is used (the deflection angle is 20 °). However, an image can be obtained.

Also, the same processing can be performed in the case of three dimensions. That is, after the processing using the equation (M′3 ″) in the case of three dimensions and the like, instead of the equation (M′4) which is the wave number matching with interpolation processing, the equation (M′11 ″) is used. ')On the basis of,
However, when interpolation approximation is not performed in wave number matching, the wave number in the depth direction represented by the proviso in the equation is used. It is divided by the speed (E'1). The same applies hereinafter.
And the three-dimensional inverse Fourier transform [Equation (M'4 ″) of Equation (M′5) represented by the same ky of (M′4 ′ ″ ″) is obtained. '6)] or instead of formula (M'4),
However, when interpolation approximation is not performed in wave number matching, the wave number in the depth direction represented by the proviso in the equation is used. It is divided by the speed (E'1). The same applies hereinafter.
The equation (M′4 ″) is obtained by performing wave number matching involving the interpolation process represented by the equation (M′4 ″ ″ ″) and the equation (M′4 ′) represented by the same ky. 5),
A two-dimensional inverse Fourier transform [corresponding to the equation (M′6)] of the product obtained by multiplying by is executed.

In the above, if the equations (M′3 ″) and (M′3 ′ ″) are interchanged and processed, the result is that soft transmission steering is performed (when the deflection angle is non-zero). An error occurs that the image position shifts. In addition, in these processes, the wave number represented by using the ultrasonic angular frequency ω ₀ and the converted propagation velocity (E′1) instead of the expression (M′10) which is the wave number corresponding to the ultrasonic frequency.
If the soft reception steering is performed (when the deflection angle is non-zero), the generated deflection angle causes a larger error than the equation (M'10). However, an image is obtained.

Further, in this case, when the migration method based on the equation (N4) described in paragraph 0314 is used, when the physical transmission deflection angle of the focus beam is A, the soft transmission deflection angle and reception angle Where θ (= θt) and θr are respectively expressed by the wave number (M13) expressed by using the angular frequency ω and the reduced propagation velocity (E1) instead of the expression (M3) (M3 ′). ') In the same way, and when the physical transmission deflection angle of the plane wave is A and the soft transmission deflection angle and the reception angle are θ (= θt) and θr, respectively, the equation (M3) Instead of (M3 ′ ″), the following formula (N4 ′) may be similarly used instead of formula (N4) in formula (M6) or (M7).
However, when interpolation approximation is not performed in wave number matching, the wave number in the depth direction expressed by the proviso in the equation is used, and the wave number in the depth direction when performing interpolation approximation is the angular frequency ω converted propagation velocity ( It is divided by E1). The same applies hereinafter.

Further, the three-dimensional case (when the migration method based on the formula (N′4) described in paragraph 0329 is used) can be similarly processed. When the physical transmission deflection angle of the focus beam is represented by the elevation angle A and the azimuth angle B (including the case where at least one of the angles is zero degree), the soft transmission deflection angle (elevation angle θ ₁ and When steering is performed at azimuth angle φ _{1 and} steering dynamic focusing is performed at deflection angles (elevation angle θ ₂ , azimuth angle φ ₂ ) (including the case where at least one of the angles is zero degrees), the formula (M Instead of '3), an equation (M'3'') represented by using a wave number (M'13) represented by using an angular frequency ω and a converted propagation velocity (E'1) is similarly used, Further, when the physical transmission deflection angle of the plane wave is represented by the elevation angle A and the azimuth angle B (including the case where at least one of the angles is zero degree), the soft transmission deflection angle (elevation angle θ ₁ and When steering is performed at azimuth angle φ _{1 and} steering dynamic focusing is performed at deflection angles (elevation angle θ ₂ , azimuth angle φ ₂ ) (including the case where at least one of the angles is zero degrees), the formula (M The formula (M′3 ′ ″) is similarly used instead of the formula (3), and the following formula (N ′) is used instead of the formula (N′4) in the formula (M′6) or (M′7). 4 ') may be similarly used.
However, when interpolation approximation is not performed in wave number matching, the wave number in the depth direction represented by the proviso in the equation is used, and the wave number in the depth direction when performing interpolation approximation is the angular frequency ω converted propagation velocity ( It is divided by E'1). The same applies hereinafter.

  In this way, beamforming based on these migration methods can also be performed in the same manner as the method described in paragraphs 0314 and 0329, with or without interpolation approximation processing in wave number matching.

In addition, when the processing described in paragraphs 0314 and 0329 for method (1) is combined with method (1) and method (2) (reception deflection dynamic focusing is performed in method (1) described in paragraphs 0233 to 0236). ) Can be similarly implemented. That is, in the two-dimensional case, when the same result is obtained when the deflection angle θ in the formulas (F42) and (F43) is calculated as zero, the formula (M9) is multiplied in the method (6) to calculate the inverse Fourier transform. Similar to the case of performing the conversion, the expression corresponding to the expression (16) may be multiplied by the expression (M9) before performing the processing described in paragraph 0202 or 0203. In the case of three dimensions, when the same result is obtained when all the deflection angles θ and φ in equations (G22) and (G23) are calculated as zero, the two-dimensional case in method (6) is used. As in the case of performing the inverse Fourier transform by multiplying the complex exponential function corresponding to the equation (M9), the multiplication may be performed while performing the processing described in paragraph 0205.
Also in these beam forming, as described in paragraphs 0314 and 0329, the interpolation processing may be performed or not performed in the wave number matching. Others are as described in the same paragraph.

  Based on these migration methods, all beamforming described in the method (4) can be similarly performed.

  Further, as described in the method (5), when transmission and reception are performed in a rectangular coordinate system other than the Cartesian coordinate system such as the polar coordinate system, the equation (M6), the equation (M6 ′), the equation ( It is possible to obtain the result directly in the Cartesian coordinate system by calculating the result obtained by performing the Jacobian operation on M7) and the equation (M7 ′) and performing the above-mentioned beam forming. Also in the case of three dimensions, the Jacobian operation is applied to the formula (M'6), the formula (M'6 '), the formula (M'7), and the formula (M'7') in exactly the same manner. Can be processed. Besides, all the beamforming described in the method (5) can be similarly performed.

It is to be noted that one of the objects of the present invention is to realize high-speed and high-precision beamforming on the basis of Fourier transform. However, interpolation approximation using the above methods (1) to (6) is performed. Any of the non-existing processes can be used by modifying it into a process in which various forms of interpolation approximation are mixed, and the accuracy may be reduced, but the speed may be increased. In the three directions of the lateral direction, the elevation direction, and the depth direction, at least one direction, two directions, or all three directions are approximated by wave number matching, or whether multiplication of a complex exponential function is used. The method can be modified and used. If many approximations are performed, the speed can be increased, but the accuracy is reduced. Some of the above explanations have already been given. In this paragraph, (A), (A '), (B), (B'), (C), (C '), ( Interpolation approximation formulas are shown for the eight cases of D) and (D ').
For example, when the plane wave steering is performed by the migration method of the method (6), the same processing can be performed, and when the wave number matching in all directions is approximated by interpolation (corresponding to (D ')), the interpolation approximation by the method (1) is performed. Similar to the method of J.-y. Lu et al. (See paragraph 0195, which corresponds to (C ′)) for processing, the calculation is the fastest when migration is used. However, the accuracy is the lowest in the migration. On the other hand, in the method of J.-y. Lu et al. (See paragraph 0195, corresponding to (C ′)), for example, if only the wave number matching in the lateral direction is performed before the Fourier transform, the accuracy is improved, but the calculation speed is higher. It falls (corresponds to (C)). Including the cases of (A), (A ′), (B), and (B ′), the interpolation process (expression) in the case of two dimensions (paragraph 0314) is shown below (in the case of three dimensions (paragraph 0329). ) Is also represented in the same way, omitted). Note that (A), (A '), (C), and (C') are represented according to the equations (7) and (8). In addition, in (B ′) and (D ′), the inverse Fourier transform in the horizontal direction is performed on kx ′ instead of kx.
The wave number k _y in the depth direction when performing the interpolation approximation in the wave number matching is the angular frequency ω divided by the propagation velocity c, but can be processed as described above when the interpolation approximation is not performed.
The wave number k _y in the depth direction when performing the interpolation approximation in the wave number matching is the angular frequency ω divided by the propagation velocity c, but can be processed as described above when the interpolation approximation is not performed.
However, when interpolation approximation is not performed in wave number matching, the wave number in the depth direction represented by the proviso in the equation is used. It is divided by the speed (E1).
However, when interpolation approximation is not performed in wave number matching, the wave number in the depth direction represented by the proviso in the equation is used. It is divided by the speed (E1).
The wave number k _y in the depth direction when performing the interpolation approximation in the wave number matching is the angular frequency ω divided by the propagation velocity c, but can be processed as described above when the interpolation approximation is not performed.
The wave number k _y in the depth direction in the case of performing the interpolation approximation in the wave number matching is the angular frequency ω divided by the propagation velocity c, which is one of the present invention. According to (1), the processing can be performed as described above.
However, in the case where the interpolation approximation is not performed in the wave number matching which is one of the present invention (one of the method (6)), the wave number in the depth direction represented by the proviso in the equation is used. The wave number in the depth direction when performing is the angular frequency ω divided by the converted propagation velocity (E1).
However, when interpolation approximation is not performed in wave number matching, the wave number in the depth direction represented by the proviso in the equation is used. It is divided by the speed (E1).
Also in these cases, the method (2) may be used together in the reception beamforming.
It is important to perform the initial multidimensional Fourier transform and the multidimensional inverse Fourier transform at high speed, and various fast Fourier transform algorithms can be used appropriately. In addition, all of the methods other than the beamforming [method (1) to method (6), etc.] described in the present specification can be realized by the processing without interpolation approximation processing or through the approximation processing. When performing interpolation approximation processing, the sampling frequency may be increased to improve accuracy, but unlike the case where a signal at an arbitrary position can be generated when interpolation approximation processing is not performed, the number of Fourier transform data increases. Things need attention. However, even when the interpolation approximation processing is not performed, it is important to appropriately perform oversampling to realize a situation in which the signal is processed with a high SN ratio.
In such a case, also in the case of using the migration process [method (6)], the beam forming (collective reception signal at the time of simultaneous transmission of a plurality of different beams or waves) described in methods (1) to (5) Beamforming for superimposing received signals for each transmission, including the case of using a virtual source or a virtual receiver) can be performed with or without interpolation approximation.

Method (7): Others In the above methods (1) to (6), the case where a one-dimensional array is mainly used has been described. Then, in each of the other one or the other two axial directions, the processing performed in the lateral direction may be similarly performed. These can be implemented in all Cartesian coordinate systems, including Cartesian curved coordinate systems. That is, it is sufficient to simply extend the above methods (1) to (6) to higher dimensions. Further, during the processing of the methods (1) to (6) and the method (7) described here, a horizontal direction or a vertical direction DC component or a low frequency component may be generated. It is advisable to perform the zero padding processing of the spectrum before the inverse Fourier transform of. Before starting the digital signal processing, analog processing or digital processing is performed as a pre-processing to turn off the direct current, but the spectrum may be zero-filled in the angular spectrum.

Further, also in beamforming using other Fourier transforms in Non-Patent Document 9 or the like, the method disclosed in the methods (1) to (7) can be used, and the same effect can be obtained. .
For example, Section 2.4 of Non-Patent Document 9 discloses a method of calculating an arbitrary beam or wave using a general solution (Green function) of the wave equation. There, spherical waves, cylindrical waves, and plane waves are treated as examples of analytical calculation. As a feature of using the Green's function, the signal to be obtained has a denominator in the frequency domain as
have. Using the method, it is possible to calculate using the Green's function in a cylindrical coordinate system, a spherical coordinate system, or any other orthogonal coordinate system.
That is, in the method or the formulas disclosed in the methods (1) to (7) (when interpolation approximation is not performed in wave number matching and when it is performed), the spectrum of the signal to be obtained has the denominator as the formula (GR1) or (GR2). Should be calculated in the situation that The methods and mathematical expressions described in the methods (1) to (7) can be applied to various other methods and beamforming.
Further, in these cases using the Green's function, since a point source can be considered, it is suitable to represent a virtual source (Patent Document 7 or Non-Patent Document 8) set before and after the physical aperture. In that case, the processing for the actual radiation pattern of the physical aperture (element) described in the next paragraph is important.

  Further, the methods (1) to (7) can be applied, for example, to the calculation in consideration of the radiation pattern of the aperture (element) described in Section 3.2 of Non-Patent Document 9. In that case, the signal strength may be appropriately corrected and signal processed by physical or soft apodization. As described in many cases in this specification, for example, ISAR, non-linear processing, adaptive beamforming (Non-Patent Document 10), and various other processing are performed to improve resolution (particularly, orthogonal to the propagation direction). Direction) and side lobes may be suppressed to increase the contrast. The coherent factor and the like in Non-Patent Document 11 and the like can also be applied. Further, the apodization (which may also serve as a delay by using a complex signal) is appropriately performed without being limited thereto. The apodization includes a case where the apodization is variable not only in the propagation direction but also in the scanning direction.

  The methods (1) to (7) can also be used when transmitting or receiving apertures at various positions are used or when various other beamformings are performed. For example, Non-Patent Document 9 provides abundant examples. For example, there are descriptions of Geophysical Imaging (for example, pay attention to the form of formula 7.9 to formula 7.12) and so-called X-ray CT (Computed Tomography) in Section 7.3. Also, the present methods (1) to (7) can be used. Also noteworthy is FIG. 7.3 and equations 7.5-7.9 disclosed in the case of certain transmission imaging described in Section 7.2 of Non-Patent Document 9. In these, processing including wave number matching and the like can be performed without performing the interpolation approximation processing (in those cases, the interpolation approximation processing may be performed).

  In addition, the present methods (1) to (7) are predetermined biplanes, multiple planes, planes or tomographic planes that spread in a desired arbitrary direction (in these, planes or tomographic planes are not necessarily flat, but curved surfaces). In some cases) or on a line (a line is a straight line or a curved line) rather than a surface, the image signal can be selectively and directly generated. For example, while an image can be presented on the basis of a three-dimensional or two-dimensional image signal, the image may be presented on the basis of those image signals, or the image may be presented on its own. It is possible. Further, in signal processing, those image signals and images may be presented through interpolation approximation. Further, in those cases, the measurement data such as the displacement, strain, temperature, etc. measured based on the image signal or the image may be displayed individually, or may be displayed by being superimposed on these images.

  As described multiple times herein, apodization can be determined and performed in various ways. There are various adaptive beamforming, minimum variance beamforming, Capon method, etc. described in Non-Patent Document 10 and the like. In these, when the covariance matrix is regularized, the parameter for adjusting the degree of regularization (regularization parameter) can be appropriately determined for each position based on the SN ratio of the signal at each position. , Can be processed spatially as a variant. Alternatively, instead of using an identity matrix for the regularization operator, it is also possible to use other positive definite operators such as gradient operators and Laplacians. It is possible to increase the resolution of the image signal (in particular, the direction orthogonal to the propagation direction), and it is also possible to increase the contrast by suppressing the side lobes. Also, in independent component analysis (independent signal separation), it is effective to regularize the covariance matrix in the same manner. These regularization methods have not been disclosed so far. Alternatively, in both processes, the process is also stabilized by lowering the rank based on singular value decomposition or eigenvalue decomposition. These processes are similarly effective in other methods in beamforming. As described elsewhere, MIMO (Multiple-input and Multiple-output: wireless communication technology that combines a plurality of antennas on the transmitting side and the receiving side to expand the band of transmitted and received signals) and SIMO (Single-input and Multiple-output) : It is also effective to use one antenna on the transmission side and use a plurality of antennas on the reception side to expand the band of the received signal. Further, the inventor of the present application has long preferd to use absolute value detection or power-law detection in addition to envelope detection, but the coherence factor in Non-Patent Document 11 or the like is effective. Absolute value detection and exponentiation detection are effective in visualizing wave undulations. If you take an absolute value or apply exponentiation, it will have a high frequency component, especially if the order is high, but you may assign brightness to the amplitude of the wave itself or assign it to color (these Can also be considered as a biased detection). Non-Patent Document 10 describes various other adaptive beamforming, and this specification also describes MUSIC (Multiple Signal Classification: wireless communication technology using eigenvalues or eigenvectors of correlation matrix of received signal) and the like. Various processes are described. The effective processing is not limited to that, and there are various other types. Such various treatments can be performed before, during, and after the beam forming treatment, and can also be performed at the apodization level. In that case, it is extremely effective to perform the processing after performing the spatiotemporal alignment based on the correlation processing.

  Further, in the present invention, in particular, the SN ratio of the signal may be improved by performing integration processing (calculation) in the time direction (distance direction) in which the rf data is acquired. This integration processing is also performed by analog processing (so-called integrator) or digital processing (integrator or integration calculation).

  Further, in the above description, the calculation of the product with the weight value, which is easy to perform in the apodization process and has a small amount of calculation, has been described. Convolutional integration may be performed based on a dual relationship between the product at and the convolutional integration. Appropriate apodization is possible at each depth position or at equal distances from each aperture element.

The above-described lateral modulation signal (image signal) and the lateral broadband are obtained by the process of superposing the multi-directional deflected beams and plane waves generated by the apparatus according to the present embodiment using the methods (1) to (6). In some cases, a signal (image signal) that has been converted into high resolution in the horizontal direction is generated. Similar to the case of single transmission, physical or soft steering, or both steering may be performed in each, and the same steering may be applied to all of them. Although the reception beamforming is mainly described as being performed by software, the reception beamforming using the reception delay or the reception apodization may be physically performed alone or in combination as occasion demands. On the other hand, although transmission beam forming is described mainly as being physically performed, a high frame rate can be obtained by, for example, transmitting a plane wave or transmitting a plurality of beams or waves. In order to perform surface synthesis, transmission may be performed for each element (multi-directional aperture surface synthesis is also possible, plane waves, cylindrical waves, spherical waves, etc. are coded and transmitted, and decoding is performed for aperture surface synthesis. It is also possible to do). As described above, in terms of software, it is possible to consider and implement transmission and reception in reverse. Compared to the focus beam, the plane wave reaches a deeper position (the echo is also obtained from a deeper position), but the SN ratio as a wave or beam is compared when the displacement is measured. And low. In the first place, the resolution in the horizontal direction is also low in comparison. On the other hand, when plane waves in multiple directions are superposed, almost the same lateral resolution can be obtained regardless of the position. On the other hand, when using the focus beam, it is effective to intersect the beams in multiple directions at the focus position, but in order to obtain high lateral resolution at multiple positions, multi-focusing is required. Will be done. In any case, it is possible to achieve high-speed beamforming with respect to a received signal when a plurality of waves or beams are transmitted at the same time, or a signal obtained by superimposing received signals transmitted at different times even in the same phase. .. In addition, a plurality of waves having different carrier frequencies may be used to generate a signal (image signal) having a wide band in the axial direction and a high resolution in the axial direction. In those cases, the bands may be broadened so that the spectra overlap with each other to improve the resolution. These plural beams may be simultaneously generated in parallel, and the measurement targets may be generated at the same time phase but at different times. Multi-directional waves may be generated by the above multi-directional aperture plane synthesis.
When the deflection angle is increased, the image forming positions of the reflector and the strong scatterer may be spatially displaced. For example, when the deflection angle is transmitted to the front of the aperture element by changing the deflection angle in increments (for example, 1 °) up to ± 45 ° and the beamformed signals are superimposed, the plane wave is opened in the front direction. The case of surface synthesis can be simulated, and a band corresponding to a deflection angle of ± 45 ° cannot be obtained in the lateral direction (signals are canceled during superposition). It is natural to consider the case where the beam forming in the front direction is decomposed into a plane wave as an angular spectrum. When widening the band in the horizontal direction by superposition in the space-time or frequency space, not only in the case of polarized plane wave transmission, but also in the case of performing other polarized beam forming, it is necessary to select a spectrum whose spectrum does not overlap in the frequency space. It is necessary to superimpose them, but there is a cause that the image forming position is spatially displaced. Therefore, when superimposing signals with large deflection angles, at the time of transmission at the time of beamforming, or at least one of the reception signal before reception beamforming, during reception beamforming, and after beamforming, It may be necessary to correct the position of the signal. When performing super-resolution (spectral processing or nonlinear processing of superposition, or superposition of spectral processing or nonlinear processing, etc.) in combination when performing super-resolution by spectral processing or nonlinear processing of these signals, The effect (positional error, etc.) that the positional deviation has on the result becomes remarkable, and such positional correction may be important. In addition to this, the frequency dependency of the converted propagation velocity is also a factor that causes the positional deviation, and the same problem may occur when signals with different frequencies are superposed, and may be similarly processed. The position correction is also described in paragraph 0369 and the like. Various signal processing techniques such as motion compensation and phase aberration correction can be used. The signal strength correction is also described in paragraph 0663 and the like. Regarding the beamforming component and the speckle component of the weak scattering signal, unlike these decisive signals, a virtual sound source and a virtual receiver assuming a scatterer invented by the inventor of the present application (Patent Document 7, As confirmed by experiments using Non-Patent Document 8, it can be used for imaging and displacement measurement without performing position correction processing (for example, for displacement measurement, combined use of plane wave transmission and Gaussian apodization is effective. , A power type apodization such as a square function is effective at the time of focusing, and the latter has high resolution even in single beam forming).

  Further, it is different in order to form multi-focus (including not only normal multi-focus in which the transmission focus is formed at a plurality of positions in the beam propagation direction, but also including transmission focus at an arbitrary plurality of positions including the lateral direction). A process of transmitting a plurality of waves focused on a position and performing reception beamforming may be performed. Further, a process of generating a reception beam at a plurality of positions or a reception beam in a plurality of directions may be performed on one transmission beam. In addition, beamforming may be performed based on transmission in a plurality of directions with different steering angles. In addition, beam forming may be performed at a distant position where there is little interference, or beam forming may be performed at each part divided within one frame on the basis of performing transmission and reception. In some cases, parallel beam forming, such as parallel processing, is performed, and in each case, the results are overlapped at each position in the region of interest where a plurality of beam forming results are obtained. The method (4) itself has a characteristic that it is possible to process a received signal of an interfering wave as long as the wave propagates in the region of interest, and by utilizing this, a high frame rate can be realized. (Method (4) is capable of receive beamforming for any transmit beam or wave, single or multiple transmissions). In addition, beam forming may be performed using appropriate signal components after performing various signal separation processes. Depending on the degree of interference, the waves outside the region of interest may be processed without being eliminated.

  In addition, the opening for transmitting or receiving the wave may be a dedicated opening for each, but since it may serve as both, it does not always receive the response of the wave sent by itself, but it was sent from another opening. Waves may also be received and the resulting beamforming results may be overlaid, including when processed in parallel. In summary, the above-mentioned superimposition is simultaneous or simultaneous phase in which the states of the object (communication target) and the observation target for propagating the waves are the same or substantially the same, or different time, or different time. In one phase, there may be more than one beamforming or transmission or reception at each aperture, and likewise one combination of apertures may have more than one beamforming or transmission or reception. Sometimes it is done. Similarly, each of the plurality of combinations of apertures may perform one or more beamforming, or transmission or reception. In addition, in those cases, when a plurality of beamforming or transmission or reception results are obtained, new data may be generated through the calculation of their superposition.

  Since the superposition processing is linear processing, it is possible to superpose a plurality of complex spectrum signals having the same frequency in the frequency domain in the calculation process of the above methods (1) to (6). The inverse Fourier transform of the superposed complex spectra may be performed at a time, and in the case of superposing as described above in the spatial domain after the generation of a plurality of beamformed waves, the inverse Fourier transform of the number of superposed waves can be performed. Processing can be completed faster than needed. Although not limited to this, incoming waves, etc., may be processed in a single direction or a plurality of directions, for example, those superimposed in the state of angular spectra. As the process itself, it is good to superimpose a plurality of waves in the spatial domain and perform Fourier transform to obtain the superposed angular spectrum (the Fourier transform is effective only once). It may be possible to confirm the location of the target object.

  Further, in the above, in the case of transmitting a plurality of beam-formed waves (at least with a predetermined transmission delay and sometimes with transmission apodization) (methods (1) to (6), In methods (2) and (3) other than aperture plane synthesis, the first excited aperture element in the effective aperture array of each transmitted wave when physically transmitting at the same time. Are excited at the same time), and the respective received signals are stored in the memory or the storage device (storage medium) in an overlapped state, so it is sufficient to perform the generation processing of the image signal of one frame according to each method. (In some cases, one frame is divided and each part is processed in parallel.)

  On the other hand, in the other case described above in which beamforming is performed a plurality of times at different times, it is possible to grasp the timing of transmission from the first excited aperture element in the effective aperture array in the channel of each reception aperture element. In the apparatus according to the embodiment, the digital signal processing unit may appropriately superpose a plurality of received signals so as to obtain the same signal as a received signal when a plurality of waves are transmitted at the same time, and perform the same processing ( In this case as well, parallel processing may be performed in which one frame is divided and each part is processed). In these cases, in effect, the first Fourier transform only needs to be done once (there may be processing divided in each part).

  In such an active case, the beamforming can be completed at a higher speed in the beamforming except the aperture plane combination (methods (2) and (3)). However, the received signals for aperture plane synthesis collected for the methods (2) and (3) are subjected to transmission beamforming (transmission delay or transmission apodization is applied if necessary) and superimposed. And may be processed in the same way. By the way, if the reception signals are superposed without applying the transmission delay, in this case, the reception signal when the plane wave is transmitted without steering can be generated. Even in the aperture plane synthesis processing, the division parallel processing may be performed to increase the speed. In particular, when performing multi-directional aperture plane synthesis, which is the past invention of the inventor of the present application, one time phase is used. In the apparatus or method of the present invention, it is possible to generate beams in a plurality of directions from the signals collected in the above, and under the deflection angle in each direction, the same angle obtained by one Fourier transform is obtained. The calculation is performed using the spectral data, and finally the multidimensional spectra obtained by superimposing the multidimensional spectra obtained for each deflection angle are not performed multiple times, and the multidimensional spectra are superposed one time. It is possible to generate a final image signal at high speed by Fourier transform (sometimes performing division processing). However, even if fixed focusing of reception or other beam forming is performed by passive processing even by aperture plane synthesis, as described above, for superimposed reception signals (that is, one angular spectrum), For example, it is effective to perform processing in a single direction or a plurality of different directions.

  Further, in the case where the superposition of a plurality of waves obtained in these processes is obtained, for example, if the propagation direction, the frequency, or the band is different, it is also effective to process the spectrum separately. In addition, encoding, MIMO, SIMO, MUSIC, independent signal separation (independent component analysis), principal component analysis, code, or a parametric method can be used for separation in the digital signal unit. The superimposing process may be effective in other cases (for example, the SN ratio is improved by using a plurality of signals obtained in the same phase).

  Independent signal separation (independent component analysis) is effective, for example, in separating a specular reflection signal and a scatter signal. In contrast to a signal including the specular reflection signal, an independent scatter signal is generated between two or more frames. When the processing is performed by realizing the state that the signal has or the state in which the independent scattering signal is mixed, the specular reflection signal that commonly exists can be effectively separated. This is useful for automating the detection / separation (removal) of high-intensity signals from blood vessels, etc., and the identification (detection) of the blood flow region when measuring tissue displacement such as blood flow. is there. In addition, it is also useful for detecting and extracting boundaries such as organs and tumors, and can similarly detect (specify) specular reflection (tissue), separate (remove), and identify (detect) the range of characteristic regions. . At the same time, it is also possible to separate the mixed independent scattered signals, and rather than detect the corresponding signals from each of the sums (that is, the arithmetic mean) and differences of the signals between frames, independent component analysis (independent Component separation) has higher detection ability for specular reflection signals and separation ability for mixed signals. The ability of them is higher when they are processed after detection (envelope detection, square detection, absolute value detection, etc.). This is not limited to visual confirmation, but can be quantitatively and quantitatively evaluated for confirmation or confirmation. In addition, by applying measurement of displacement, strain, etc., performing motion compensation (translation, rotation, expansion / contraction) with respect to translation, rotation, deformation, etc., and performing alignment and processing, their capabilities are improved (( When displacement measurement based on cross-correlation is performed with a simulation of 3 MHz frequency, even if the specular reflectance distribution of 0.1 to 0.5 when the standard deviation of the scattered signal is 1.0, even if the scattered signal of similar intensity is mixed, Motion compensation is required.) Processing with spatial resolution is desirable. It is more accurate to measure displacement etc. before detection, but it may be performed after detection. When high-precision displacement measurement is performed using, block matching (phase matching) in the spatiotemporal domain, which may be performed through oversampling or upsampling, or movement by phase matching based on phase rotation in the frequency domain. Compensation is useful: a separate signal can be used with a medical ultrasound transducer by tilting the transducer to pick up the specular signal at the same position from another angle, or using a different sub-aperture based on the steering process. Alternatively, it is also effective to shift the scan plane and collect signals including specular reflection signals from the same specular reflection signal source (series of the same structure and composition) (measurement technique). It is also possible to positively apply motion (scan plane is shifted or signals from other tissues are mixed) and deformation (possibly including noise), and as mentioned above, signals including specular reflection signals. Similarly, when using ultrasonic waves (sonar, etc.) or electromagnetic waves other than medical ultrasonic waves, the movements of sensors, signal sources, and detectors (camera shakes, disturbances of their holders, etc.) are similarly detected. It is sufficient to collect and process reflected or transmitted waves by applying wave or beam steering, target movement or deformation. Occasionally, the generated analog or digital (including software-like noise) noise is mixed in. Note that these processes are not only for separating specular reflection signals and scattered signals, but also for common signals between signals. It can also be used to obtain the same effect for signals and mixed signals, and the application range is not limited to this. Homogeneous propagation velocity, medium disturbances and condition changes (eg pressure and temperature changes, etc.) Depending on the change in the propagation velocity, etc., the signal may be processed in pure signal analysis. Although the frame signal was described, it may be applied to the beam-formed (including aperture plane synthesis), or before the reception beam forming or without beam forming (transmission / reception signal for aperture plane synthesis). Beam forming may be performed after the treatment. That is, it may be performed before, during, or after beamforming. In each case, super resolution may be used together. The motion compensation process described above is effective not only for correcting the spatiotemporal shift, but also for correcting the shift when the signals at the time of transmitting the focusing beam or the plane wave are compared and referenced (for example, in super-resolution). . In addition, the above-described motion compensation processing, which may be performed before or during beamforming, may also serve as a delay (delay) processing in the DAS processing. Also, detection (absolute value detection, square detection, envelope detection, etc.) and high resolution through linear or non-linear processing, which will be described in detail later, are similarly applied to the beamformed (including aperture plane synthesis). In some cases, the beam forming may be performed before the reception beam forming or after the beam forming is not performed at all (a transmission / reception signal for aperture plane synthesis). That is, it may be performed before, during, or after beamforming. When widening the band in these processes, if necessary, oversampling or upsampling is performed in the space-time, or the band is widened by zeroing the spectrum in the frequency domain (inverse Fourier transform is performed. For example, the result of oversampling or upsampling is obtained).

  Signal separation is performed by frequency operation and power band expansion (when the order is greater than 1) or frequency band narrowing (when the order is less than 1) by power calculation, and then the frequency domain In, there is a case where it is performed with high accuracy. Restoration of the signal after separation may be performed simply by using the reciprocal power of the power order used.

On the other hand, in the methods (1) to (6), the spectrum is frequency-divided and the received signal stored in the memory or the storage device (storage medium) to generate the image signal of one frame is displayed after the wave number matching. It is also possible to obtain a plurality of processed waves in a situation where the spectrum is divided in the frequency domain. In some cases, the angular spectrum is divided and each is processed. In either case, the band of the signal component may be limited for processing. Even if a plurality of waves overlap, the spectrum may be frequency-divided in the same manner. The frequency division of these spectra corresponds to the generation of physically pseudo waves having new wave parameters (frequency, band, propagation direction, etc.). The divided spectra may be processed in parallel. The superposition process is also a process of generating new wave parameters, but it may be superposed in the spatial domain and the angular spectra may be superposed, or the spectra may be superposed before the inverse Fourier transform. However, if necessary, the angular spectra after the Fourier transform may be superposed, or the signals after the inverse Fourier transform may be superposed. Applying the reversibility of Fourier transform (Fourier transform and inverse Fourier transform), the generated signal is returned to the signal before receiving beamforming (before transmitting and receiving beamforming in case of aperture synthesis), and other beamforming is performed. It may be performed (for example, different steering angles for transmission or reception, a plurality of waves with different steering angles for one transmission, etc.).
As super-resolution processing, we will describe spectral weighting processing, non-linear processing, and imaging of instantaneous phase excluding phase rotation, but in addition to this Fourier beamforming, it may be processed under DAS processing. .. For example, as described above, high-speed imaging is possible when transmitting a wave widely spread in the lateral direction such as a plane wave, a circular wave, a cylindrical wave, and a spherical wave. As described above, it is possible to enhance their effects by generating and superimposing a plurality of waves with different steering angles for transmission or reception, superimposing them on a wide band in the lateral direction, and then performing super-resolution processing on them. It is valid. The superposition of plane waves, etc. is realized when focusing is performed without depending on the depth position in terms of phase, and based on the above-mentioned spectrum weighting processing, for example, in the case of performing apodization using a Gaussian function, a rectangular wave is used. It is effective to target high-resolution imaging using aperture surface synthesis based on apodization using a power function and to compensate for its spectral intensity. So to speak, the superposition corresponds to calculating the inverse of the calculation of the Angular spectrum based on plane wave separation in Fourier imaging. In some cases, focus and aperture plane synthesis may be performed on each other. It is important to adjust the steering angle to be overlapped, and if the angle difference is small, the band is not widened only by looking at the spectral intensity relatively in the lateral direction (the relatively low spectral intensity is not widebanded. There is a SN ratio of the band, especially when the aperture plane synthesis process is performed), but if they are overlapped with a certain angle difference, the band is broadened in the situation where there is spectral intensity. For the band having a relatively low spectral intensity when the angle difference is small, for example, the weighting process of the spectrum is effective. Since the signals having different phases are superposed, the signal strength is low, and therefore it is necessary to perform double-precision calculation processing (beamforming, super-resolution processing, etc.) as necessary. On the other hand, if there is a certain angle difference, a wide band signal can be easily obtained with a small number of waves or beams. In them, it is also effective to normalize and superimpose wave energy. Similarly, the other two super-resolutions are also effective. Of course, a superposition process in which waves with different focus positions and ultrasonic frequencies are superposed is also effective as a super-resolution method. Although it is possible to superimpose the results obtained by subjecting each wave to super-resolution, the amount of processing is smaller and the effect is higher when the superposition is performed. Phase compensation (compensating for inhomogeneity of sound velocity) in superposition is important.
Also, so-called compressed sensing may be performed. Similarly, it may be performed in the DAS process. Similar to the above three super-resolutions, it may be applied to superposition of a plurality of waves. The above three super-resolutions require less computation, but combinations of them, including Compressed Sensing, may be processed.
Here, some examples of DAS processing that may be performed in the present invention will be summarized.
-DAS processing (method D1) performed by a normal digital diagnostic device
In order to perform reception dynamic focusing, when reading the ultrasonic signal stored in the memory of each channel after AD (Analogue-to-Digital) conversion processing, the distance between each receiving element position of each channel and each point of interest is measured. The stored signal is read (ie, Delay) from the memory at the address that means the time of digital reception. Then, those signals within the effective aperture width are added (Summation). According to this method, since an error occurs in Delay depending on the sampling frequency of the received signal, it is natural to perform sampling based on the Nyquist theorem, but sampling should be performed at a high frequency as much as possible. It has the characteristic of being fast.
・ High-precision DAS processing of method D1 (method D2)
While performing DAS processing based on method D1, in order to improve the accuracy of Delay processing, the complex exponential function is applied to the analytic signal a (t) of the received signal calculated based on the Hilbert transform, and the phase rotation is performed. By performing the delay, the accuracy of the time t ₀ shorter than the sampling time interval is obtained, and the addition processing is performed.
a (tt ₀ ) = a (t) exp [-jω ₀ (t) t ₀ ]
Here, ω ₀ (t) is either the ultrasonic nominal frequency, the center of gravity (center) frequency, or the instantaneous frequency. Although it is more accurate than the method D1, it is an approximation process using the frequency ω ₀ (t) at the sampled position. It is affected by frequency modulation such as attenuation and scattering. As with method D1, a higher sampling frequency is better. It has high speed.
The theoretically most accurate DAS process (method D3)
This is a method that the present inventor has invented in the past, but the spectrum A (ω) of the local signal including the signal at the point of interest is multiplied by a complex exponential function in the frequency domain, and the phase of the local signal is rotated to perform Delay. ..
A '(ω) = A (ω) exp [jωt ₀ ]
This is an interpolation process that satisfies the sampling theorem, and is theoretically the most accurate, but requires a calculation time.
・ Fourier beam forming (method D4)
This is beamforming, which is the basis of the present invention. This is a method of performing digital wave number mapping in the multidimensional frequency domain of the received signal, and can perform fast Fourier transform to calculate the accuracy equivalent to that of method D3 at a significantly high speed. As a feature different from the other commonly reported Fourier imaging methods, interpolation approximation processing is not required in the digital wave number mapping, but interpolation near processing can be performed in order to achieve higher speed. However, in that case, it is required to increase the sampling frequency in order to reduce the deterioration of the accuracy caused by the artifact.

  A displacement vector (multidimensional autocorrelation method, multidimensional auto Doppler method, etc. (Non-Patent Document 13)) that moves in an arbitrary direction is used in a digital signal unit by using a plurality of waves generated in these processes. A method of solving simultaneous equations regarding components is used to measure the displacement in one direction with high accuracy by the inventors of the present application's past invention) (derivation of more equations than the required number of displacement components and overdetermination) In an (over-determined) system, an accurate result can be obtained in a state where the least squares method, the average value of calculation results, and waves overlap each other and the frequency is high and the band is wide, for example. An equation is derived one by one from each wave generated. Ordinary Doppler method may be applied to one wave. Each wave may be a superposition of waves, or may be a spectrum that is frequency-divided or a spectrum is processed. It is desirable that each wave has a high frequency, a low frequency spectrum may be removed, and a wide band is desirable when high spatial resolution is also required (Non-patent Document 1). Reference 14). A window capable of weighting the spectrum may be used for the division and processing. From the displacement (vector), strain (tensor), strain velocity (tensor), velocity (vector), and acceleration (vector) are obtained by partial differential processing using a differential filter with respect to space or time. These can be used to determine the (viscous) shear modulus, viscosity, average normal stress, density, etc. In addition to this, as a method for measuring the displacement (vector), a multi-dimensional cross spectrum phase gradient method (one of block matching methods, Patent Document 6 and Non-Patent Document 15), which is the past invention of the inventor of the present application, is used. There is also a digital demodulation method (Patent Document 7), and similarly, distortion and the like can be measured. Further, by using these, it is possible to measure the propagation of shear waves and waves of low frequency vibration. (Viscosity) Shear elastic modulus, shear wave propagation velocity, propagation direction, shear wave displacement, frequency, phase, vibration amplitude, vibration velocity, vibration acceleration, etc. can be measured. These can also be obtained as a distribution.

  In order to improve the accuracy of this displacement measurement, the inventor of the present application invented that the regularization is performed in the past. In order to determine the regularization parameter of the punishment term, for example, in a posteriori, the variation of the measured displacement (vector) is estimated and used under a (local) steady process (Patent Document 6), or in a priori, The inventors invented using Ziv-Zakai Lower Bound (ZZLB, for example, the variation shown in Non-Patent Document 16) by using the characteristics of waves or beams (for example, Non-Patent Documents 17 and 18).

  In the present invention, these variations and ZZLB are used for weighting in order to adjust the reliability of each equation when the Doppler equations derived as described above are simultaneous (the high reliability is heavy, The one with low reliability is set low). That is, at each position in the region of interest, their values are obtained from each of the above-mentioned waves or beams, and the Doppler equations derived from the corresponding waves or beams at each position are weighted to obtain simultaneous equations. solve. Using the least squares method, Weighted Least Squares Solution (WLSQS) can be obtained in a posteriori or a priori.

The simultaneous equations of the Doppler equation derived above are
Where u is an unknown displacement vector of the interest point or the local area including the interest point or its distribution, b is a vector representing the phase change of the interest point or the local area relating to the interest point or the distribution thereof, and A is the corresponding It is a matrix composed of frequency components in a local region or distributions of the respective interest points arranged in parallel, and the components of A and b may be subjected to moving average processing in the time direction and the space direction. In the case of demodulation, the Doppler equations in which only the displacement components having the carrier frequency in the two or one directions are unknown are in a simultaneous state.
When it is expressed as follows, the reciprocal of variability or ZZLB is used and weighted using itself or its power or a matrix W representing its distribution.

In particular, focusing on one point of interest or local region, one Doppler equation (or multiple, ie, cross-spectral phase gradient method) derived from one of the waves or beams p (= 1 to N). When is used, the number of simultaneous equations that hold for the phase spectrum in the signal band for the cross spectrum obtained in the local region, and the block based on the multidimensional autocorrelation method or the multidimensional Doppler method are used. When performing matching, the reciprocal value Wp of ZZLB calculated at the interest point or the local region is the same as the number of formulas that are simultaneous at the position in the local region). Since it is the reciprocal of ZZLB of the displacement in the beam direction, for example, when the unknown displacement of the interest point or the local region is the three-dimensional vector u = (Ux, Uy, Uz) ^T ,
However, Axp, Ayp, and Azp (p = 1 to N) are frequency components in the x, y, and z directions, and are components of the matrix A of formula (A1) or formula (A2), and bp (p = 1 to N) is a phase change between frames, which is a component of the vector b of the same formula, and Wp is a diagonal component of the matrix W of the formula (A2). Wp is applied to all simultaneous equations when the cross-spectral phase gradient method (one of the block matching methods) is used and when the block matching is performed based on the multidimensional autocorrelation method or the multidimensional Doppler method. (That is, in one p, multiple equations are simultaneous, and all of them are multiplied by Wp).

For example, when Cramer-Rao Lower Bound (CRLB) is established according to ZZLB described in Non-Patent Document 16, its squared variance is:
However, T is the moving average width when calculating the frequency or phase change in the case of the multidimensional autocorrelation method or the multidimensional Doppler method, and is the multidimensional cross spectrum phase gradient method, the multidimensional autocorrelation method, or the multidimensional Doppler method. When the block matching is performed by the block measurement, the length in the beam direction of the local region of the displacement measurement is used, f _0b is the ultrasonic frequency in the beam direction, B _b is the rectangular bandwidth in the beam direction, and SNRc is the SN of the echo. SNRe, which is the ratio, and SNRρ, which is the correlated SN ratio (the signal ratio for the noise component that is generated due to the reduced correlation due to the distortion of the waveform due to the displacement or the deformation of the object)
However, ρ is a correlation value when a local cross spectrum is obtained between frames, or a correlation value locally obtained by the length of the moving average width.
Combined SN ratio
Is.

Therefore, the variation may be estimated by measuring and using T, f _0b , B _b , SNRc, SNRe, SNRρ, and ρ, as described in Patent Document 17, for example. As described in Non-Patent Document 19, f _0b may be obtained by obtaining an instantaneous frequency or a first-order moment (center of gravity, that is, a weighted average value), and B _b is a second-order central moment. It can be estimated by finding the square root.
In the case of a multidimensional signal, it may be calculated including two axes (that is, three dimensions) or one axis direction (two dimensions) orthogonal to the frequency axis of the beam direction. For example, when the signal is three dimensions,

  On the other hand, the SN ratio SNRe of the echo can be statistically estimated by repeatedly collecting the echo for the object or the calibration phantom. In some cases, a typical value is used a priori based on the object, its state, measurement experience, and the like. On the other hand, the correlation SN ratio SNRρ can be estimated using the correlation value ρ locally evaluated at each interest point. The methods for obtaining these are not limited to these. In addition, if either value is lacking and the variation cannot be estimated absolutely, the typical value can be used, but when setting the regularization parameter, it is expressed in the possible range. The variation may be multiplied by an undetermined proportional constant, and the best situation result may be obtained from the good or bad results obtained by changing the proportional constant (for regularization, for example, Patent Document 6, Non-Patent Document 17 or 18).

Here, when the first moment and the second central moment in the beam direction are not directly estimated but they are estimated in each direction (for example, when the signal is three-dimensional, the first moment in the x-axis direction is estimated). The first moment f _0x and the second central moment Bx are
Alternatively, when a method different from ZZLB is used and the variation in each component of the displacement vector is estimated without directly estimating the variation in the beam direction displacement, the following estimation can be performed. That is, the propagation of the error to the beam direction displacement may be considered under the assumption that the stochastic processes of the measurement errors of those displacement components are independent. For example, when each of the average value and the variation of the displacement of the three-dimensional displacement vector is estimated to be (mx, σx), (my, σy), (mz, σz), the average value m _beam of the displacement in the beam direction is Each of the variations σ _beam can be estimated as follows.

Further, parameters described in equation (A4) ~ formula _{(A6) (T, f 0b} , B b, SNRc, SNRe, SNRρ) is provided for each direction, the average f _0x in each direction of displacement, f _0y, f _0z and variation σ _CRLBx, σ _CRLBy, σ _CRLBz are each when estimation variance sigma _CRLB beam direction of displacement, according to equation (A8),
It can be estimated that

It is similarly derived when the unknown displacement of the position of interest is a two-dimensional vector u = (Ux, Uy) (when there is one unknown displacement, such as a displacement U in one direction or a displacement U in the beam direction). Is used for the estimated value itself).

  When the displacement is obtained for each point of interest or each of the local regions related to the point of interest, the equation (A2) that is established by simultaneous establishment of the weighted Doppler equations (A3) [p = 1 to N] that hold at that position is solved. The number of waves or beams (ie the number of equations) N must be greater than or equal to the number of unknown displacement components. However, when the above block matching is performed, a plurality of equations (A3) are established from one wave or beam p as described above. Therefore, the measurement may be performed with a smaller number of waves or beams as compared with the case of using another displacement measurement method.

At the same time, in the case where regularization is also performed, when all the equations (A3) that are satisfied in a plurality of points of interest in the area of interest or local areas related to the points of interest are simultaneous, and the unknown vector u has a displacement component distribution. The regularized weighted least squares solution (RWLSQS) may be obtained by obtaining the equation (A2). The variation or ZZLB may be used as the regularization parameter at that time (a value proportional to the variation, a value proportional to a power, etc.). Details of regularization are described in, for example, Patent Document 6 and the like. The dispersion of displacement in each wave propagation direction or beam direction may be used as a regularization parameter of displacement in all directions, and the dispersion of displacement in each direction estimated for each wave or beam may be different. It is also used as a regularization parameter for displacement in the direction. For example, as the distribution of the unknown three-dimensional displacement vector (Ux, Uy, Uz) ^T , an unknown vector whose distribution vectors Ux, Uy, Uz are displacement vectors Ux, Uy, Uz When u = (Ux, Uy, Uz) ^T is calculated, a matrix W having a displacement Wp (p = 1 to N) in the beam direction as a diagonal component, or a displacement Wpx, Wpy in each direction, Using the matrices Wx, Wy, and Wz each having Wpz [p = 1 to N] as diagonal components, the least squared error energy E (u) and its solution u are expressed as follows.

The variation and ZZLB may be subjected to an averaging process on the measurement result of the displacement component obtained by simultaneous selection of the selected Doppler equations, and may be used for weighting in that case. Using the reciprocal Wp (p = 1 to N) of the displacement variation in the beam direction or the reciprocal (Wpx, Wpy, Wpz) of the displacement variation in each direction [p = 1 to N], the weighted average is calculated. It may be required.

  In addition to the steady process and ZZLB, the variation may be obtained based on an ensemble average under a non-steady process, may be obtained using a calibration phantom, or may be obtained from the measurement target itself. As described above, the regularization parameter and the weighted matrix are determined, but in some cases, a typical value may be a priori determined based on the object, its state, measurement experience, and the like. Also, this is not the case.

  As described above, the weight value and the regularization parameter can be set with high accuracy in the state of having a spatial resolution, but when the deformation is small or the calculation amount is reduced, a region larger than the local region (for example, In some cases, the variation is estimated for the entire region), and the waves or beams are globally set and processed. The phase matching method (Patent Document 6 and Non-Patent Document 15) invented in the past by the inventor of the present application is required to enable the measurement itself and to improve the measurement accuracy. The expansion and contraction methods that have been reported elsewhere are useful for chemical conversion.

A Wiener filter can also be applied as Wp. In the spatiotemporal region, the signal itself is directly weighted, and then the signal is imaged or displacement is measured. The signal is a signal r (x, y, z) before or after detection.

  The noise signal n (x, y, z) can be statistically estimated by repeatedly collecting echoes on an object or a calibration phantom. For example, variation can be used, and a case where a steady process is assumed is locally used for the estimation by an addition average, or an estimation is performed with an ensemble average. In some cases, a typical value is used a priori based on the object, its state, measurement experience, and the like. Also, this is not the case. When envelope detection, square detection, or absolute value detection is performed to detect the signal r (x, y, z) for imaging, the formula (A12) or the formula (A13) is applied at each position. Sometimes. Also, when the conjugate of the analytic signal is multiplied by the analytic signal to obtain the power spectrum and the self function is obtained, the weighting can be similarly performed. It should be noted that it is also possible to use the auto-correlation method and the Doppler method, which are displacement measurement methods that use analytic signals, as well as the pre-processing of signals before using the cross-spectral phase gradient method or cross-correlation method (the analytic signals may not be used). Can be used.

  When the signal is two-dimensional or one-dimensional, r (x, y) instead of r (x, y, z) and n (x, y, z) in the formula (A12) and the formula (A13), respectively. And n (x, y), and r (x) and n (x) can be similarly processed. Further, in each beam or in a region of interest obtained by scanning with each beam, the formula (A12) or the formula (A13) may be globally obtained and used. Instead of equation (A12) or equation (A13), equations (A4) to (A6) may also be directly used for echo weighting.

Further, in particular, when the multidimensional cross spectrum phase gradient method (Patent Document 6, Non-Patent Document 15) is used, the Wiener filter can be applied not only in the spatiotemporal domain but also in the frequency domain. As described above, for each wave or beam, the frequency range of cross spectrum Hp (ωx, ωy, ωz) [p = 1 to N] between signals before and after deformation or displacement acquired under the same conditions ( In obtaining the gradient (three-dimensional unknown displacement vector) of the phase spectrum θ (ωx, ωy, ωz) in ωx, ωy, ωz) using the least squares method,
However, PWpn (ωx, ωy, ωz) and PWps (ωx, ωy, ωz) are power spectra of noise and signal, respectively, and PWps (ωx, ωy, ωz) is a cross spectrum size instead. Squared (|| Hp (ωx, ωy, ωz) || ² ) may be used. q is an arbitrary positive value.

The least squares are obtained by weighting represented by For example, in formulas (1) to (14 ′) of Patent Document 6, a description is given when the square of the magnitude of the cross spectrum (|| Hp (ωx, ωy, ωz) || ² ) itself is used for weighting. However, Wp (ωx, ωy, ωz) may be used instead of the weight (variation of displacement in the beam direction and ZZLB may be used as described above). is there). It should be noted that the least-squares is evaluated for each of the N waves or beams with p = 1 to N and is least-squared at each interest location at once.

  The power spectrum PWpn (ωx, ωy, ωz) of noise can be statistically estimated by repeatedly collecting echoes on an object or a calibration phantom. In some cases, a typical value is used a priori based on the object, its state, measurement experience, and the like. Also, this is not the case.

  In addition, n (x, y, z) / r (x, y, z) represented in the formulas (A12) and (A13), the formula (A12 ′) and the formula (A13 ′) PWpn (ωx, ωy, ωz) / PWps (ωx, ωy, ωz) is the reciprocal of the echo SN ratio SNRe, or the combined SN of SNRe and SNRρ that is the correlated SN ratio. It may be set based on the reciprocal of the ratio. Further, in a state where there is a spatial resolution, or in each beam or in a region of interest obtained by scanning with each beam, the formula (A12 ′) or the formula (A13 ′) is globally obtained, and the formula (A12) or Like the formulas (A13) and (A4) to (A6), it may be directly used for echo weighting (imaging or displacement measurement). Further, when the signal r (x, y, z) is detected (envelope detection, square detection, absolute value detection, etc.) for imaging, the expression (A12) or the expression (A13) may be used. However, in that case, the square norm of the first spectrum Hp (ωx, ωy, ωz) [however, the spectrum of the local signal or the signal extending to the region of interest] in the equation does not have to be used. The same applies to the case where the conjugate of the local spectrum Hp (ωx, ωy, ωz) is multiplied by the spectrum Hp (ωx, ωy, ωz) to obtain the power spectrum and the autocorrelation function signal is obtained.

  When the unknown displacement is the two-dimensional vector u = (Ux, Uy) or the unknown displacement is U (one) in the beam direction, H (ωx, ωy, ωz in Equation (A12 ′) and Equation (A13 ′) ), The weights similarly expressed by using the respective Wiener filters for the cross-spectrum H (ωx, ωy) and H (ωx) between the signals before and after the deformation or displacement can be used.

  Further, when performing regularization, the above-described variation and the like may be used to set the regularization parameter in the same manner according to Equation (10) and Equation (10 ′).

  When using the cross spectrum phase gradient method or another block matching method, it is possible to obtain displacement vectors in two or more directions by using one wave or beam independently, and one wave or beam is used independently. Even so, an over-determined system can be constructed.

  Further, in any of the above displacement measurements, it is possible to perform the measurement without using the over-determined system, and in that case, the above weighting or regularization may be performed.

There are also various techniques for detecting or imaging the movement of an object based on the observed wave motion.For example, in the field of medical ultrasound, the average velocity and dispersion of blood flow and tissue displacement and deformation can be determined. There are some that can display speed information, presence / absence of movement, complexity, and the like. In some cases, a contrast agent (microbubble) is actively used, and measurement imaging is performed in a state in which the intensity of waves from blood in blood vessels or heart chambers is enhanced. It may be effective not only for morphological observation but also for functional measurement. Radioisotopes used in PET (positron emission tomography) are typical examples of self-emanating contrast agents, and observation based on counting the number of occurrences is performed. This is a target device of the passive device of the second embodiment. For example, a magnetic substance (which may have an affinity for a target such as a cancer lesion) is intravenously injected, and the mechanical force is applied to the device. Vibration may be applied to generate a magnetic field. Therefore, the transmitting transducer is mechanically stimulated, and as a response, electromagnetic waves are observed by the receiving transducer. Further, the above-mentioned photoacoustic and the like are also possible. For example, ¹⁸ FDG is a typical PET imaging agent ⁽¹⁸ F- fluorodeoxyglucose, label the positron-emitting nuclide in glucose) are ingested glucose more than cancer cells are normal cells (3 to 20 fold) It is used for the early detection of cancer in the whole body by applying this property, and by applying photoacoustics (photoacoustic) to this, it is possible to detect cancer early by receiving ultrasonic waves (accumulation mechanism by metabolic trapping There is, like glucose, is taken up by the cell membrane via the glucose transporter of the cell membrane and metabolized by the enzyme hexokinase, but unlike glucose, it remains in the cell without proceeding to the glycolysis system.) It may be used in combination with PET, but ultrasonic examination may be performed separately from PET. The processing itself is based on the reception beam forming for an incoming ultrasonic wave (transmitted wave) using a trigger based on the timing of laser irradiation. Positrons are emitted from positron-emitting nuclides (positron nuclides) by β ⁺ decay, attract each other, and combine with the electrons after a few mm to disappear, and at that time, two photons emitted in almost opposite directions ( γ-rays, Chi immediately, such as by observing the annihilation radiation), but the spatial resolution is low, in the region that can be observed ultrasonic waves are generated, as compared, there is an advantage that can be observed with high resolution. It is also suitable for early detection, and it is also possible to observe the presence or absence of disease depending on the presence or absence of accumulation, and to determine the degree of malignancy or progression by observing the extent of the disease from the intensity of the photocoustic signal ( Glucose metabolism is increased in malignant tumor cells, resulting in high accumulation). In addition, for example, the brain has the most glucose metabolism in the human body, and Alzheimer-type dementia is accompanied by metabolic abnormality from an early stage. Further, in the myocardium, glucose metabolism is enhanced when ischemia progresses (positive), but glucose metabolism is not performed when necrosis occurs. Photoacoustic can be used for those observations. May is craniotomy in the case of the brain, when the target disease abdominal deep organs, abdominal or, such as using a laparoscope (Haraanakyo) and catheters, Ya laser irradiation in the vicinity of the disease Ultrasonic detection may also be performed. In these applications, in many of them the light absorption frequency characteristic of the contrast agent has become known are elucidated, sometimes the frequency dispersion of the ultrasonic signal generated illumination laser 及 beauty is actively used, Further, imaging is not always performed, and only quantitative observation based on numerical values may be performed. As described above, the glucose concentration is an observation target, and can be applied to blood glucose level observation and imaging. Further, the PET imaging agent, in addition to sugar, oxygen, which water, amino acids, nucleic acids, a positron emission nuclide to neurotransmitters such as labeled ⁽¹¹ C - methionine, ¹¹ C - acetate, ¹¹ C - choline, ¹¹ C - methyl spiperone, ¹³ N-ammonia, ¹⁵ O-water, ¹⁵ O-oxygen gas, ¹⁸ F- Furuorodo Pas etc.) have been put into practical use, such as those developed for them and Photoacoustics, separately developed It can also be used for various contrast agents. In these photoacoustics, Doppler measurement (including vector measurement) may be performed on blood, urine, and body fluids with and without the use of contrast agents, and soft and hard tissues may be measured. In some cases, displacement and deformation of organs, viscoelasticity, and thermodynamic characteristics are also observed.

  In addition, the wave is separated before the final inverse Fourier transform and detected (square detection, envelope detection, etc.), or after the last inverse Fourier transform is separated and detected, or is separated from the original. Can be detected before and after Fourier transform (Non-Patent Document 1), and an image showing the intensity distribution of each wave can be imaged, or those that have become incoherent signals by detection can be superimposed. , Enhances deterministic signals (eg, reflection signals or specular signals) and reduces stochastic signals (eg, scatter signals or speckle signals) to reduce the space of the structure of the object or medium. Change is effectively visualized (past invention of the inventor of the present application).

  In some cases, coherent signals with overlapping waves are detected and their intensity distribution is imaged. In addition, a coherent signal that has not been detected may be imaged to image the corrugation itself, or an image of a phase distribution obtained together with an image of signal intensity (amplitude) may be presented. It may be imaged similarly for a single wave.

  The display method is generally gray image or color image (popular), but at that time, if quantitativeness is required, a numerical value corresponding to the displayed brightness or color may be displayed as a bar. is there. In addition, it may be displayed in a bird's-eye view or the like, and may also be displayed in combination with CG. They may be displayed as still images or videos, videos may be displayed frozen, they may be displayed in real time, or they may be processed and displayed offline. There is also. The wave data or image data stored in the storage device (or storage medium) may be read and displayed. The change over time of arbitrary numerical values may be displayed as a graph.

  In addition, for example, it is also possible to observe the temperature distribution of the measurement target by using a signal in the microwave, infrared ray, or terahertz band. The wave transmitted to the radiating object is modulated and detected (the passive type device according to the second embodiment also measures the temperature distribution of the target from the radiated wave itself). Sometimes it will be). As with other waves, spatial resolution can be obtained by using pulse waves, burst waves, or beamforming instead of continuous waves, and infrared rays are mainly used when observing the temperature distribution on the surface of the target ( It may be considered that only the surface of the target is considered), and microwaves or terahertz can also be used to observe the temperature distribution inside the target. On the basis of these observed physical and chemical quantities, higher-order processing such as an inverse problem approach is performed, and the viscoelastic modulus, elastic modulus, viscosity, thermophysical properties, and electrical properties (conductivity and dielectric constant) , Magnetic permeability, wave propagation velocity (light velocity, sound velocity, etc.), attenuation, scattering (forward scattering, backward scattering, etc.), transmission, reflection, refraction, or wave source may be obtained including frequency dispersion. .. In medical applications, including the use of ultrasound and MRI, observation of viscoelasticity in addition to the temperature and thermophysical properties of the inflamed part after cancer lesions and heating / heat treatment, and those treatments and surgery. And monitoring may be performed. In addition, body temperature observation (morning, day, night, metabolism, growth, aging, before and after eating, smoking, including peripheral system load, electrophysiological nerve control, etc.), exercise load in various organs, etc. Then, it may be observed. It is not limited to medical applications, but other organic and inorganic substances, as well as those composed by mixing, may be the target of observation, and various observations and monitoring are linked in diagnosis, repair, application, etc. May be implemented. The application of terahertz can be applied not only to those measurements but also to other waves such as transmitted waves and reflected waves, and can be applied to Doppler measurement and the like. Characteristically, it can be applied to the observation of inorganics as well as X-rays. Other waves may be used for observing organisms and inorganics, but it is also possible to use them simultaneously with other waves for Fusion.

  The measured physical quantities such as displacement and temperature may also be displayed as an image in the same manner, but may also be displayed by being superimposed on a morphological image obtained at the same time. An image showing these distributions is often required to have a quantitative property, and a numerical value corresponding to the displayed brightness or color may be displayed as a bar. In addition, it may be displayed in a bird's-eye view or the like, or may be displayed together with CG. They may be displayed as still images or videos, videos may be displayed frozen, they may be displayed in real time, or they may be processed and displayed offline. There is also. The wave data or image data stored in the storage device (or storage medium) may be read and displayed. The change over time of arbitrary numerical values may be displayed as a graph.

  Further, other devices may provide additional information regarding the wave to be observed through the input device, and may also provide observation data of other physical quantities or chemical quantities. In addition to processing, data mining, independent signal separation (independent component analysis), principal component analysis, sign, multidimensional spectrum analysis, signal separation by MIMO, SIMO, MUSIC, signal separation based on object identification by parametric method, In some cases, high resolution processing such as super-resolution or ISAR (Inverse synthetic aperture), which may use these methods together, is performed. In other words, the beam-formed (including aperture plane synthesis) may be subjected to super-resolution, or it may be used before reception beam forming or when no beam forming is performed (aperture plane synthesis transmit / receive signal). Although beam forming may be performed after performing super-resolution processing, in each case, those methods may be used together.

  Since these processes are performed also in the passive type device according to the second embodiment, a detailed description will be given there. However, unlike the case of the passive device, in the active type device according to the present embodiment, Since it is transmitted and scanned, the position of interest can be specified in the received signal that is received is greatly different, and if transmission focus or multi-focus is performed, the state and function of those focus positions and the wave source If there is information about the wave source, it modulates and demodulates the wave with high resolution to understand them, and also a plane wave (flat array), a cylindrical wave (ring array), a spherical wave (spherical shell array). It is also possible to catch them at a high frame rate at high speed by using waves similar to.

  When performing communication, the position of the communication destination can be narrowed down from the transmitting transducer to save energy and improve communication security. The observation system has a high degree of freedom in constructing the measurement system. Further, in the processing based on those system theory, it is easy to identify the point spread function to be generated and adjust it according to the purpose. It is possible to use multiple transmitters and receivers (which may also serve as transmitters), and the waves to be transmitted and received may or may not be of the same type. As a result, a plurality of device main bodies dedicated to a plurality of transducers that operate in synchronization may be used, or a passive device according to the second embodiment may be used in combination, and It may be connected to another device including a device that controls the device via a dedicated or ordinary network, or the device body may have a network control function.

  Based on various observation data, devices for manufacturing materials and structures, devices for treatment and repair, devices to which they are applied (robots, etc.) may operate in conjunction, but are not limited to these. . It should be noted that measurement using these waves and high-order calculation processing may be carried out by another device using the wave data stored in a removable storage device (storage medium). Data may be stored in a storage device (storage medium) of the same type and used by another device.

  When the received signal received and stored in the memory or the storage device (storage medium) contains the harmonic component generated in the target or medium, the fundamental wave or the harmonic wave is generated before the beamforming process. In some cases, the beam (only the second harmonic may be used, or a plurality of higher harmonics may be used without ignoring higher-order components) may be separated for beamforming processing (normal phasing addition). However, it may be separated after the beam forming is performed. Although there is a method of separating the spectrum in the frequency domain as the separation method, the bands may overlap, and so-called pulse inversion method in so-called medical ultrasound produces waves with opposite polarities in the simultaneous phase. In the device according to the present embodiment, when the received signals for each transmission are superposed before or after beamforming, the second harmonic component can be extracted and the fundamental wave can also be obtained.

  In addition, a method of separating using a polynomial is also known. In the device according to the present embodiment, one-dimensional processing in the wave propagation direction, or when the wave is modulated in the lateral direction, or the propagation direction of the wave is strictly different. It is possible to perform multidimensional processing in consideration of the change in position, and it can be performed before or after beamforming. However, in the case of performing beamforming after separation, when performing beamforming of each of the fundamental wave and the harmonics, each beamforming process needs to be performed, which requires a calculation time, and therefore parallelism is required. Although processing may be performed, separation is faster after beamforming.

  On the other hand, when the wave transmitted from each transmission aperture is encoded, the wave generated by which transmission aperture element is transmitted is generated for the reception signal received by each reception aperture element when performing beamforming. It is well known that the components may be separated by signal detection based on a matched filter to perform not only the dynamic focusing of reception but also the dynamic focusing of transmission. This is effective for high-speed transmission by plane wave transmission, and is also effective when performing a focus beam or steering.

  Further, in the case of simultaneously transmitting a plurality of waves or beams, for example, waves having a plurality of different frequencies or a plurality of different propagation directions described above are transmitted as encoded signals, and the received signal is received. May be improved in the same way by separating them into received signals generated by their respective waves and transmission beams. This is effective, for example, in the case where the propagation directions are the same due to waves with overlapping bands, refraction, reflection, transmission, and scattering. It is based on the basic idea of encoding separate waves with a different code. It may be simply encoded under the same physical parameters.

  In these, simultaneous equations can be solved, but the processing is fast and the effect of the matched filter can be obtained. Code suitable for the target and medium has also been developed. However, as the number of elements used increases, the code length increases and the signal energy increases, making effective use of this important, but on the other hand, for example, when the target or medium is deformed, the accuracy Is known to be unsuitable due to a decrease in the noise, and a similar problem occurs in the chirp signal compression.

  In communication, the wave transmitted from each transmission aperture element is coded with information to be transmitted and transmitted (as the beamforming, for example, a plane wave, a cylindrical wave, or a spherical wave is used. In some cases, the focus may be in multiple positions, the accuracy at those positions is guaranteed, and security may be ensured to communicate locally or with a specific target, or energy may be saved. ), The received signal is beamformed and then decoded. Applications of encoding in the device according to the present embodiment are not limited to those, but these processes are performed in a digital signal processing unit (also having a memory built-in type), a memory, or a storage device (storage medium). ..

  In addition, a physical quantity (displacement, velocity, acceleration, strain, size or direction of strain rate, temperature, etc.), chemical quantity, or additional information observed by the device according to the present embodiment or provided by others. In addition, viscoelasticity and elastic modulus related to waves, viscosity, thermophysical properties, electrical properties (conductivity and permittivity), transparency, etc. Constant or appropriate or fixed time based on magnetic susceptibility, wave propagation velocity (speed of light or sound, etc.), attenuation, scattering, transmission, reflection, refraction, wave source, material, structure, or frequency dispersion thereof. Beamforming parameters such as transmit intensity, transmit / receive apodization, transmit / receive delay, steering angle, transmit / receive time interval (scan rate), frame rate, number of scan lines, number of effective apertures, etc. The shape, size, orientation and position, shape, size and orientation of the aperture element, orientation of the physical aperture, polarization mode, etc.) may be optimized. This allows, for example, spatially uniform qualities (spatial resolution, contrast, scan rate, etc.), and certain targets to be detected (based on shape, material, structure, motion characteristics, temperature, humidity, etc.). High quality (spatial resolution, contrast, scan rate, etc.) at the selected position and its related position, scattered wave (forward scattered wave or back scattered wave), transmitted wave, reflection according to the movement, composition and structure of the object. Optimized beamforming is performed such that a wave or a refracted wave is appropriately captured or is observed from a wide direction in a focused manner.

  The propagation velocity of waves is determined by the physical properties of the medium, but the physical properties change depending on the environmental conditions such as pressure, temperature, and humidity, and the physical properties are often inhomogeneous in the medium. Is. The propagation velocity may be measured in real time, or the propagation velocity can be obtained from the observed environmental condition based on the calibration data for the environmental condition. The apparatus according to the present embodiment further includes a phase aberration correction unit that corrects the non-uniformity of the propagation velocity, and substantially adjusts the transmission delay itself of each channel or the delay dedicated to correction at the time of transmission. Phase aberration can be corrected. Further, after the reception, in order to correct the inhomogeneity of the propagation velocity in the transmission path of the transmission and / or the reception, the digital signal unit can be corrected by the multiplication of the complex exponential function in the frequency domain. Alternatively, it is also possible to directly correct the above-mentioned calculation of the Fourier transform and the inverse Fourier transform. The reliability of the measured propagation velocity is calculated by generating an imaging signal for the measurement target itself or a reference object that is present in the vicinity of the measurement target or installed, and measures the imaging state, spatial resolution, signal intensity, contrast, etc. It can be confirmed as an index and may be further adjusted based on this. Also in the passive second embodiment described below, phase aberration correction of transmission and / or reception may be performed after reception.

  Waves propagate and spread while being affected by attenuation, scattering, transmission, reflection, refraction, etc., and basically, the strength of the wave becomes weaker with the propagation distance. Therefore, in the device according to the present embodiment, for example, based on the Lambert's law, a function for performing attenuation correction on a signal before or after beamforming is installed, The correction may be provided at each position or each distance, but as described above, it may be provided with the function of performing the optimal correction before or after the beam forming process in accordance with the object. In these processes, although the degree of freedom is low, the high speed of the process is emphasized, and the analog process by the analog device or circuit may be performed instead of the digital process.

  In the above processing, the superposition and the spectral frequency division are linear processing, but after the generation of the wave by the beam forming of the above methods (1) to (6) or after the generation of the wave, a non-linear processing is performed, and another A signal with wave parameters is generated. In the beamforming process, when the received signal is an analog signal, it is based on analog signal processing using an analog circuit (diode, transistor, amplifier, dedicated non-linear circuit, etc.), and when it is a digital signal, a digital signal processing unit is used. Based on the signal processing, the received signal may be subjected to exponentiation operation, multiplication operation, or other non-linear processing. Non-linear processing may be performed on the spectrum in the frequency domain.

  In addition, as a modification of DAS, DAM (Delay and Multiplication) processing, which is the invention of the inventor of the present application, may be performed in the frequency domain in the apparatus of the present invention. The products such as exponentiation and multiplication in the space-time domain can be calculated by convolution in the frequency domain. Regarding the frequency of a signal, widening the band, simulating harmonics, and steering wave, it is possible to obtain a signal that is detected from at least any one direction to all directions. For example, the resulting wave In some cases, it is possible to generate an image of, and it is possible to measure the displacement vector by using a normal one-direction displacement measuring method.

  It is also possible to generate an imaging signal using a virtual source. As for the virtual source, it has been reported in the past that the virtual source is installed in front of the physical aperture and the virtual source is installed at the transmission focal point position. Has been reported to be installed at an arbitrary position, and a physical source of wave motion and a detector can be installed at an arbitrary position of an appropriate scatterer or diffraction grating (Patent Document 7, Non-Patent Document 8). The invention can also be implemented in those virtual sources and virtual detectors, as described above. It is possible to increase the spatial resolution and widen the field of view (FOV). Further, in the case of performing beam forming of transmission or reception, or transmission / reception with respect to a reception signal obtained by transmission using one or more apertures (transmission / reception for aperture plane synthesis when beam forming is performed or not) , At least one of a plurality of wave parameters, a plurality of beam forming parameters, and a plurality of transducer parameters (element shape and size, arrangement, number, effective aperture width, element material, etc.) are different from each other. By doing so, multiple beams or waves with different characteristics can be generated (including obtaining multiple beams or waves from the same received signal), and an over-determined system can be configured. Similarly, an over-determined system can be constructed by changing the position and distribution (shape, size, etc.) of the. Also in this case, a plurality of beams or waves having different characteristics may be generated from the same received signal. In some cases, the characteristics of the over-determining system, such as high SN ratio and high resolution by coherent superposition of them and speckle reduction by incoherent superposition of them through detection, are effective for imaging. In addition, the effect of improving the accuracy of various measurements such as displacement measurement and temperature measurement can be obtained. At least one of the plurality of wave parameters, the plurality of beam forming parameters, and the plurality of transducer parameters together with the virtual source or the virtual receiver may be different (eg, electrical or electronic or mechanical). To change the steering angle physically or softly).

An arbitrary wave source causes the wave to rotate around a coordinate system determined by the receiving aperture element array around an arbitrary position, or to be spatially shifted (for example, the axis of the transmitting aperture and the horizontal coordinate). The beam forming may be performed after the received signal is corrected for the coordinates when it is generated at a coordinate determined by the above and different from that determined by the receiving aperture). For example, when it is desired to directly generate an imaging signal in a state in which the above two-dimensional Cartesian coordinate system (x, y) is rotated about the origin by θ, the analytic signal obtained by the first Fourier transform in the time direction On the other hand, it suffices to multiply the equation (29) to proceed with the calculation, and to calculate the Jacobian and the rotation of the wave vector (kx, √ (k ² -kx ² )) and the coordinates (x, y). An image signal can be generated at high speed without losing the high speed achieved by the present invention.

However, in the case of a reflected wave, s = 2, and in the case of a transmitted wave, s = 1. Substantially, if the correction is for the transmission amount, s = 1 may be performed. Spatial shifting can also be performed in the frequency domain by multiplication with a complex exponential function. The method of rotating the wave number vector (kx, √ (k ² -kx ² )) and the coordinates (x, y) and calculating the Jacobian is as follows: (S = 1) is performed, and in that situation, the reception beamforming (s = 1) is performed and the speed is low.

  In the active type device according to the present embodiment, the same applies to the passive type device according to the second embodiment described later, but as an analog device, it may be incorporated in a transducer or a device main body. Lens and reflector (mirror), scatterer, deflector, polarizer, polarizer, absorber (attenuator), multiplier, conjugator, phase delay device, adder, differentiator, integrator, matching device, Special devices such as filters (space or time, frequency), diffraction gratings, spectroscopes, collimators, splitters, directional couplers or nonlinear media, wave amplifiers may be used in combination. In addition, in the case of targeting light, a polarization filter, an ND filter, a shield, an optical waveguide, an optical fiber, an optical Kerr effect device, a nonlinear optical fiber, a light mixing optical fiber, a modulation optical fiber, an optical confinement device, an optical memory, a dispersion shift. Optical node technology, optical cross connect (OXC), optical fiber, band pass filter, time inverting device, optical mask, etc., and optical control (wavelength conversion / switching / routing) of them. An optical add / drop multiplexer (OADM), an optical multiplexer / demultiplexer, or an optical switch element is used, and the device itself may be an optical transmission network or an optical network. Not limited to this. In beamforming, they are controlled with the device, either artificially or naturally, or likewise optimally under the mechanism as described above. Non-linear processing may be performed on the spectrum in the frequency domain.

  Under such a combination, the device according to the present invention is also used in a conventional device using waves. Examples of medical devices include ultrasonic diagnostic devices (including reflection / echo method and transmission type), X-ray CT (a contrast agent that enhances the attenuation effect may be used), X-ray X-ray, Angiography, mammography, MRI (Magnetic resonance Imaging, a contrast medium may be used), OCT (Optical Coherent Tomography), PET (Positron Emission Tomography, corresponding to the second embodiment), SPECT (Single Photon Emission Computed) Tomography), endoscope (also capsule type), laparoscope, catheter equipped with various sensing functions, terahertz imaging device, various microscopes, various radiotherapy devices (chemotherapy may be used together to enhance the therapeutic effect) ), An SQUID meter, an electroencephalograph, an electrocardiogram meter, and a HIFU (High Intensity Focus Ultrasound). Among them, the nuclear magnetic resonance imaging apparatus is originally a digital apparatus, and its application range is extremely wide, including its capability. For example, when using the electromagnetic wave observation and the inverse problem that the present inventor is working on, current distribution and electrical property reconstruction (measurement), observation of displacement and mechanical wave propagation, mechanical property reconstruction (measurement), temperature It can also be applied to all observations of distribution and heat waves, and reconstruction (measurement) of thermophysical properties. In addition to the nuclear magnetic resonance imaging system, we are also working on ultrasonic waves. As another approach, for example, in OCT, absorption spectra can be measured, and based on infrared spectroscopy, for example, basal cell carcinoma of the skin and oxygen and glucose concentrations in blood can be imaged. become. Although it can be applied to normal Near InfraRed (NIR), its distribution can be captured with a higher spatial resolution as compared with so-called NIR-based reconstruction. Further, in those cases, an ultrasonic sensor device (a microscope is also possible) is used in combination with an OCT or a laser device to perform photoacoustic imaging, and the application is not limited to them. Further, a laser or an OCT apparatus may be used to capture a tissue fluctuation with high sensitivity when no mechanical stimulus is applied, for imaging. In addition, the response to any (mechanical) stimulus, including that caused by laser light, may be the target of imaging (including observation using dynamic light generated using light). In other imaging, a chemical sensor etc. may be used. The combination of waves is not limited to these, and other sensors such as a chemical sensor may be used together with the physical sensor. The device according to the present invention is also used in various radars, sonars, optical system devices, and the like. Waves are not limited to pulse waves and burst waves, and continuous waves may be used. In addition, digital processing with a high degree of freedom may be realized and used by a dedicated analog circuit with a short operating time, and vice versa. There are various devices in various fields such as resource exploration, nondestructive inspection, and communication fields, and the device according to the present invention is also used in these fields. The device of the present invention can be used as a device in an ordinary device with respect to an operation mode (for example, imaging mode, Doppler mode, measurement mode, communication mode, etc.), It is not limited.

When the above mentioned fixed focusing beams, multi-focusing, and other arbitrary beams and waves such as plane waves are physically transmitted at the same time, it is possible to achieve a high frame rate if they can be transmitted to a wide range at once in a region of interest. .. In some cases, the same effective aperture may simultaneously transmit in a plurality of directions, and in other cases, different effective apertures may simultaneously transmit in the same direction or different directions. In addition to such cases where the steering angle and focus position are the same or different, ultrasonic frequency and bandwidth (beam direction, wave propagation direction, direction orthogonal to them), pulse shape, wave number, aperture shape and apodization In some cases, beam forming parameters such as a beam shape depending on the like, and transducer parameters such as an element shape and a size and an array condition may be the same or different at the same time.
The following can be considered as a representative case when the parameters are different in the physical multiple transmission.
(A1) When the same soft steering is applied to all of them.
(A2) When a plurality of different soft steering wheels are applied (for example, when the same steering wheel is softly applied for different transmission steering angles).
When the parameters are the same, the following can be considered as a typical case.
(B1) When soft steering is applied.
(B2) When performing a plurality of soft steering.
However, they may be implemented in combination. In some cases, so-called adaptive beamforming is performed due to obstacles in the propagation process and influences of scattering and attenuation (including a case depending on frequency). At that time, when the same combination of soft transmission and reception steering or apodization is implemented, they are processed at a time in a superposed state. When the combinations include different combinations, each combination is processed at a time in the state where the same combination is superimposed for each combination, and they are superimposed before the final inverse Fourier transform.
In the cases of (A1) and (B1), the received echo signal received as a superposition of the echo signals for the respective transmitted ultrasonic waves can be subjected to one soft processing.
In the case of (A2), it is classified into echo signals to be subjected to the same processing in terms of software, superposed for each subject to the same soft steering, and subjected to the soft processing once for each, and finally. Superimpose them before the inverse Fourier transform of. It should be noted that signal separation may be performed by using the various methods described above, and is not limited to these.
In the case of (B2), a plurality of different soft processes are applied to all the overlapping angular spectra, and they are overlapped before the final inverse Fourier transform.
In the case where those beams and waves are not transmitted physically at the same time, if the target time phases are the same or if multiple transmissions and receptions are performed under that assumption, the above simultaneous It may be processed according to the case of transmission. In addition, when the same combination of soft transmission and reception steering or apodization is implemented, they are superposed and processed at one time, and when different combinations are included, they are implemented. The combinations are superposed for each identical one, each processed at once, and superposed before the final inverse Fourier transform. Those that are transmitted at the same time and those that are not transmitted at the same time may be processed similarly under the same conditions or assumptions described above. Incidentally, those parameters in the physical transmission may be known in advance, or the beam or wave may be analyzed and used. This is true even in the case of the passive type described later.
By performing simultaneous or non-simultaneous transmission of multiple beams and waves, it is possible to realize high frame rate and focusing at the same or multiple points. Also, based on the same process including overlay processing, beams and waves with new parameters can be generated. It can be generated (for example, high resolution by widening the band), and also with frequency division processing of the spectrum, it is also possible to generate beams and waves with new parameters, and the beams and waves generated by them can be used as parameters. In some cases, each of them is used after being separated into different ones (for example, displacement measurement and displacement vector measurement in the generated beam direction and wave propagation direction). Bandwidth may be applied to the superposed state, the spectrum frequency-divided one, and the separated one based on the nonlinear or linear processing described later. In addition, superposition or spectral frequency division, separation, or non-linear or linear processing may be used for displacement measurement or the like. Each of them may be detected and imaged, or they may be superimposed and imaged (for example, speckle can be reduced). The applications are not limited to these, and are various as described above, and are not limited to those.

<Simulation result>
The following mainly shows the results of confirming the feasibility of the above beamforming methods (1) to (7) by simulation when the wave is an ultrasonic wave (a monostatic type aperture during plane wave transmission or steering). Surface synthesis, multi-static aperture plane synthesis, generation of image signal by fixed focusing, generation of image signal in Cartesian coordinate system during transmission and reception in polar coordinate system, and result of migration method).

  FIG. 16 is a diagram showing a numerical phantom used in the simulation. Here, a numerical phantom including five point scatterers existing at 2.5 mm intervals at a depth of 30 mm in an echoless and non-attenuating medium was treated. Field II (see Non-Patent Document 20) was used to generate the echo signal. Here, the depth direction is the z axis and the lateral direction is the x axis.

  A one-dimensional linear array type transducer (128 elements, element width 0.1 mm, gap 0.025 mm, slice direction thickness 5 mm) was used for plane wave transmission, migration method, and monostatic type aperture plane synthesis. In fixed focusing and multi-static type aperture plane synthesis, a one-dimensional linear array type transducer (256 elements, element width 0.1 mm, gap 0.025 mm, slice direction thickness 5 mm, effective aperture width 33 to 129 elements) was used. A convex type transducer (128 elements, element width 0.1 mm, gap 0.025 mm, slice direction thickness 5 mm, curvature radius 30 mm) was used for transmission and reception in the polar coordinate system. The center frequency of the radiated ultrasonic pulse is 3 MHz, and its sound pressure waveform is shown in FIG. The deflection angle is defined with respect to the depth direction of the front surface, and will be represented as “θ” in the following.

(1) Transmission of deflection plane wave FIG. 18A (respectively (a) to (d)) shows simulation results when deflection plane waves with deflection angles θ = 0 °, 5 °, 10 °, and 15 ° were transmitted. . Further, FIG. 18B shows a simulation result when interpolation approximation is performed in wave number matching when the deflection angle is θ = 0 °. These are the results of reception at the same angle. 18A and 18B, the horizontal axis represents the position [mm] in the horizontal direction (Lateral x), and the vertical axis represents the depth (Depth) z [mm]. As shown in FIG. 18A, a focused echo image is obtained, and it can also be confirmed that the image is deflected. Both are results of down-sampling (paragraphs 0206 and 0207) from 100 MHz to 10 MHz in the frequency domain and generating image signals at intervals corresponding to a sampling frequency of 25 MHz (the same applies to others).
On the other hand, when the deflection angle is θ = 0 °, interpolation approximation is performed in wave number matching, and FIG. 18B (e) shows sampling frequencies of 100 MHz (left) and 25 MHz (right) when replaced with a spectrum in the vicinity. 18B (f) shows the results when the sampling frequencies are 100 MHz (left) and 25 MHz (right) when linear interpolation approximation is applied to the spectrum. Although the image was more stable when the sampling frequency was high and the linear interpolation approximation was performed, the image did not reach that in FIG. 18A (a) when the interpolation approximation was not performed. When the deflection angle was set to non-zero, the result was further unstable.

  The results of calculating the obtained deflection angle from the spectrum of the generated image signal are shown in FIGS. 19 and 20. For this evaluation, the number of scatterers in the numerical phantom was increased, and 300 scatterers were randomly arranged at a depth of 0 to 40 mm. The reflection coefficient of each scatterer was a random value of -1 to 1. An error of 0.5 to 0.8 degrees was confirmed regardless of the set deflection angle. The error depends on the position of the scatterer with respect to the generated wave. The accuracy increases as the number of scatterers increases (omitted).

  FIG. 21 shows the result of superimposing a plurality of images obtained at different deflection angles. The deflection angles are set at 1 ° intervals, and 1 wave (0 °), 11 waves (-5 ° to 5 °), 21 waves (-10 ° to 10 °), 41 waves (-20 ° to 20 °). Overlaid each. FIG. 22 is a diagram in which the lateral distribution of the point spread function estimated from the generated image signal is plotted. In FIG. 22, the horizontal axis represents the position [mm] in the horizontal direction (Lateral x), and the vertical axis represents the relative value of the brightness (Brightness). As shown in FIG. 22, it can be confirmed that the resolution improves as the number of superpositions increases.

Migration method [Method (6) is applied to beamforming when transmitting the same polarized plane wave]
The result of generating the image signal by the migration method according to the present invention is shown in FIG. The deflection angles were θ = 0 °, 5 °, 10 °, and 15 °, as in FIG. 18A. In the wave number matching, the result when interpolation approximation is omitted is omitted, but the image is unstable.

(2) Deflection Monostatic Type Aperture Surface Synthesis FIG. 24 shows the simulation result during deflection by the method (2) monostatic type aperture surface synthesis. As in FIG. 18A, the deflection angles were set to θ = 0 °, 5 °, 10 °, 15 °. As shown in FIG. 24, it can be confirmed that an image is formed and the image is deflected.

(3) Synthesis of Multi-Static Aperture Surface A simulation result by the method of (3) multi-static aperture surface synthesis is shown in FIG. FIG. 25A shows a low resolution image generated by using only the received signals (that is, one set) with the receiving element equal to the transmitting element (that is, the same as the monostatic type). FIG. 25B shows a result of superposing results of a total of 33 sets in which 16 elements on the right and left sides are used for reception in addition to the element at the transmission position. 25 (c) and 25 (d) show the result of overlapping 65 sets (32 elements on the left and right of the transmission element) and the result of overlapping 129 sets (64 elements on the left and right of the transmission element), respectively. As shown in FIG. 25, it can be confirmed that an image has been formed. FIG. 26 shows the result of plotting each point spread function. From FIG. 25 and FIG. 26, it can be confirmed that the larger the number of overlapping, the more the side lobes are suppressed and that the resolution is high.

(4) Fixed Focusing The result of fixed focusing transmission is shown in FIG. Here, the method (1) was used. FIG. 27A shows the result of superimposing the echo signals received at each transmission effective aperture and performing the echo signal generation process once. FIG. 27B shows the result of generating low-resolution echo signals for each effective aperture width and superimposing them. FIG. 27 (c) shows the result of superimposing the echo signals by using the same positional relationship for transmission and reception as a set, as in the multistatic aperture plane synthesis. As shown in FIG. 27, an image is formed in any of them, and no particular difference is seen. The method (1) is faster and more effective than the other two methods. Further, the result of the method (1) shows that the reception beam forming is possible even by using a reception signal when ideally transmitting a plurality of beams or all beams simultaneously (for a transmission beam having interference) It can also process received signals and achieve high frame rates). This processing can be performed not only in fixed focusing transmission but also in multiple transmission of all types of waves (including a combination of different waves). That is, there are cases where a plurality of waves include those with different transmission beam forming, cases with and without beam forming, and cases with different kinds of waves (electromagnetic waves, mechanical waves, thermal waves, etc.). However, it may include those processed such as nonlinear processing, detection processing, super-resolution or adaptive beamforming, minimum variance processing, or signal separation. These processes may be performed during beam forming. Of course, the received signals for each transmission may also be superposed. Interpolation approximation processing may also be performed in the wave number matching in these cases.

(5) Image signal generation in Cartesian coordinate system for transmission / reception in polar coordinate system (5-1) Cylindrical wave transmission Ultrasonic waves are simultaneously radiated from all the elements of the convex array and the echo signal when transmitting a cylindrical wave The result of processing in the area is shown in FIG. As a matter of fact, as described in (5-1 '), a plane wave or a virtual linear array is generated at a depth of 30 mm in transmission and reception. As shown in FIG. 28A, it can be confirmed that the scatterer is imaged.
(5-1 ') Cylindrical Wave Transmission Using Linear Array Next, an echo signal when a cylindrical wave is transmitted using the linear array and a virtual sound source (FIG. 8A (a)) set at a position behind the linear array. The result of generating is shown. FIG. 28 (b) shows the result of using the method (1) described in the method (5-1 ′) with the virtual sound source positioned 30 mm rearward, and FIG. 28 (c) shows the virtual sound source. The result of using the method (2) described in the method (5-1 ') at a position of 60 mm rearward is shown. It can be confirmed that the scatterer is imaged.
Further, in the case of using the linear array type transducer, the method (1) described in the method (5-1 ') is used to generate a cylindrical wave using a virtual source located 30 mm behind the physical aperture. 28 (d) shows the result of the case where a plane wave or a linear array type transducer virtually expanded in the lateral direction is generated at a distance position of 30 mm (FIG. 8B (g)).

(5-2) Fixed Focusing FIGS. 29 (a) and 29 (b) show the results of processing the received signal when fixed focusing (FIG. 14 (a)) at a distance of 30 mm from each element using the convex array. . FIG. 29 (a) shows the result of superimposing the received signals obtained at the respective effective transmission apertures and performing one echo signal generation process, and FIG. 29 (b) shows the low resolution for each transmission. The result of having generated and superposed the images is shown. Similar to the multi-static aperture plane synthesis, the result of generating and superimposing echo signals with the same positional relationship for transmission and reception as a set is omitted, but these three operations are almost the same as in (4). The result of. Further, FIG. 29C shows the result of performing echo signal generation processing once on the received signal when fixed focusing (FIG. 14B) at a depth of 30 mm. The scatterers were well imaged.
These results are obtained in the same manner as (4), and it is shown that the reception beam forming is possible even if the reception signals when ideally transmitting a plurality of or all beams simultaneously are used. (Received signals for interfering transmission beams can also be processed, and high frame rates can be achieved). This processing is not limited to these fixed focusing transmissions, but can be performed when multiple types of waves of all types are transmitted (including combinations of different waves). That is, there are cases where a plurality of waves include those with different transmission beam forming, cases with and without beam forming, and cases with different kinds of waves (electromagnetic waves, mechanical waves, thermal waves, etc.). In some cases, it may include those processed such as non-linear processing, detection processing, super-resolution or adaptive beamforming, minimum variance processing, or signal separation. These processes may be performed during beam forming. Of course, the received signals for each transmission may also be superposed. Interpolation approximation processing may also be performed in the wave number matching in these cases.

  The beamforming using the digital Fourier transform according to the present invention executed in the above simulation is based on the proper use of multiplication of complex exponential functions and Jacobi operation, and performs arbitrary beamforming processing in an arbitrary orthogonal coordinate system. It was proved that it can be realized with high accuracy without interpolation approximation. Although any beamforming can be realized by using the DAS (Delay and Summation) method, the beamforming according to the present invention is speeded up by the difference between the wave number matching and the Fourier transform in the lateral direction, and when the one-dimensional array is used, a general-purpose beamforming is performed. When using a PC, the calculation time is significantly faster than 100 times. When the aperture elements form a two-dimensional or three-dimensional distribution, a two-dimensional or three-dimensional array, the above method may be made more multidimensional, and more processing than in the one-dimensional case may be performed. It solves the problem of cost, and its high speed becomes more effective. Further, an example in which superposition and the like when transmitting plane waves with different deflection angles is effective is also described. It is possible to obtain an effect that the resolution is increased, the side lobes are suppressed, the contrast is increased, and the like at high speed.

  In the above example, it was confirmed that arbitrary focus (including no focus) and steering can be performed in an arbitrary array type aperture surface shape, and the arbitrary beamforming processing in an arbitrary rectangular coordinate system can be performed at high speed and without interpolation approximation. It was confirmed that it could be realized with accuracy. The time required to obtain a high-order measurement result such as displacement measurement based on the generated image signal is shortened, and the measurement accuracy is improved. In the present invention, as described in methods (1) to (7), interpolation approximation processing may be performed in wave number matching of arbitrary beam forming, and beam forming may be performed at higher speed. In order to perform highly accurate approximate wave number matching, it is necessary to appropriately oversample the received signal at the cost of an increased calculation amount. In that case, it should be noted that the number of data of the Fourier transform is increased unlike the case where the signal at an arbitrary position can be selectively generated when the interpolation approximation process is not performed.

  The example in which the typical transducer, the reception sensor, the transmission unit and the reception unit, the control unit, the output device, and the external storage device according to the first embodiment are used has been described above. The possibility of beamforming of the methods (1) to (7) proves that arbitrary beamforming based on focusing and steering can be performed in an arbitrary Cartesian coordinate system, and the apparatus of the present invention can be used. The beamforming and the application that can be realized by using are not limited to those described in the other.

<< Second Embodiment >>
Next, the configuration of the measurement imaging apparatus or the communication apparatus according to the second embodiment of the present invention will be described. FIG. 1 is a representative block diagram showing a configuration example when the device according to the first exemplary embodiment is an active type, and FIG. 2 is a representative block diagram showing a configuration example of the device body in detail. However, in the second embodiment, a passive type device is used, and therefore the device according to the second embodiment does not include at least a transducer for transmission in FIG. It does not have a wired or wireless path for sending drive signals to the transducer.

  In the case of the active device according to the first embodiment, detailed configuration examples of the device and the unit have been described with reference to FIGS. 1 and 2 as a representative configuration, but the active device has an arbitrary opening shape. However, the passive type device is a device for transmitting and receiving a transducer array device of arbitrary aperture shape, while the transducer device array device (the transducer may be used for both transmission and reception) is always used. Not used.

  That is, the basic configuration of the device according to the second embodiment is a receiving transducer (or receiving sensor) 20, a device body 30, an input device 40, an output device (or display device) 50, and an external storage device 60. Equipped with. The device body 30 mainly includes a reception unit 32, a digital signal processing unit 33, a control unit 34, and a storage unit (memory or storage device or storage medium) not shown. Further, the device body 30 may include a transmission unit 31. The description of these components in the first embodiment also applies to the second embodiment.

  Similar to the first embodiment, each of these devices and each unit in the device main body 30 can be installed at distant places. The device main body 30 is composed of a plurality of such units, and is referred to as such for convenience. Further, similarly to the first embodiment, the reception transducer 20 may be mechanically scanned to perform reception. The same processing may be performed even when not generally called an array type.

  However, the device according to the second embodiment, unlike the device according to the first embodiment, comes from an arbitrary wave source, as will be described in detail below, in order to sense the timing at which the wave is generated. The control unit senses the timing signal generated by receiving the wave itself of the observed object itself or generating the timing signal through another process through wired or wireless communication, and captures the data of the receiving unit (each receiving channel It may be used as a trigger signal for starting AD conversion and writing to memory).

  As a method for the control unit to detect a timing signal indicating the timing at which the wave is generated, the receiving transducer (or receiving sensor) of the device according to the present embodiment is used when the wave itself coming from the wave source is used as the timing signal. The reception signal itself received by the reception aperture element 20a of 20 is used, or the timing signal received by a dedicated reception device that may be included in the device body 30 is used.

  In this case, the receiving aperture element 20a (all the elements may be used, but the elements or the like at the end or the central position may be sparsely used in the physical aperture) or a dedicated receiving device (at least a plurality of receiving channels are used). The information received about the signal strength, the frequency, the band, or the code of the received signal is continuously detected through the various input means as described above. However, it is set to the control unit 34 itself (internal memory) or the analog determination circuit (in this case, it is not variable in terms of software or hardware, but may be fixed in terms of hardware). Alternatively, the detection of the timing at which the wave is generated is performed by detecting the signal received by the receiving aperture element 20a or the dedicated receiving device in the memory or the storage device (storage medium), and determining the characteristics of the wave or the wave to be observed. It is based on matching with discrimination data such as a database regarding

  When the received signal is discriminated in an analog manner, it is discriminated by a dedicated analog circuit provided, and only when it is discriminated that the signal is an observation target, a trigger signal for data acquisition is generated and the received signal is AD. The converted beam may be stored in a memory or a storage device (storage medium), and a beam forming process may be performed.

  When a received signal is digitally discriminated, the received signal is continuously AD-converted in time and stored in a memory or a storage device (storage medium), either constantly or at any time (when a command is issued through an input device, etc.). ), At a predetermined time interval (such as set through an input device), the stored signal is read by the digital signal processing unit 33, and the digital signal processing unit 33 discriminates based on the collation with the discrimination data, and judges that the signal is an observation target signal. The beam forming process may be performed only in the case where the beam forming process is performed.

  Since the storage capacity of the memory and the storage device (storage medium) is finite, in the case of digital determination, the wave signal of the observation target was not observed within the predetermined time (such as setting through the input device). In this case, the memory address is initialized. In addition, although it is not efficient from the viewpoint of energy saving, beam forming may be performed at any time, and the wave signal may be discriminated using the discrimination data based on the image signal whose accuracy is increased by the beam forming. The process is the same even when a normal wave for communication purposes is an observation target.

  Further, the dedicated receiving device may be installed at a position apart from the units of other devices, for example, at a position near the wave source to be measured or a position where the timing signal reception environment is good. Yes, a wave that propagates at a higher speed than the wave received at the receiving aperture (a wave that becomes a timing signal) is used, and the timing signal may be transmitted to the control unit in the apparatus main body via the dedicated receiving device. .. A dedicated line (wired or wireless) that may use a relay station may be used. In this case, the reception signal is captured (AD conversion and stored in a memory, a storage device or a storage medium) and beam forming is performed using the timing signal as a trigger signal.

  Also, the timing signal in which the wave is generated may arrive after the device of the present invention receives the wave. That is, the propagation speed may be slow, or such a mechanism may be used, but it may result in such a situation. In order to deal with such a case, the reception signal is always continuously captured, the reception signal stored in the memory or the storage device (storage medium) is read back in time, and the beam forming is performed. . In that case, the information regarding the wave obtained by another observer or the observation device is added to the timing signal as additional information at the relay station, etc., and the timing signal with the additional information is transmitted for exclusive reception. Information including additional information may be read by the device and used not only in the device of the present invention but also in other devices. The line used is not limited to a dedicated line, and a normal network may be used. A similar timing signal may be used even when a wave for normal communication is an observation target. The additional information may be conveyed in a wave or signal different from the timing signal.

  In addition to the generation of the wave to be observed, a wave that propagates faster or slower than the wave received by the receiving aperture element before, during, or after the generation (wave serving as a timing signal) is the wave source. In some cases, the dedicated receiving device and the dedicated line are similarly installed and used. In that case, the information about the wave of the observation target may be added to the wave serving as the timing signal, and the information about the wave obtained by another observer or observation device is added by the relay station or the like and transmitted. The information including the additional information may be read by the dedicated receiving device and used by the device of the present invention or another device. The line used is not limited to a dedicated line, and a normal network may be used. A similar timing signal may be used even when a wave for normal communication is an observation target. The additional information may be conveyed in a wave or signal different from the timing signal.

  As these dedicated receiving devices, dedicated sensing devices capable of sensing timing signals or reading additional information are used, but any observer or any observing device (observation target Any active or passive observing device or similar observing device related to wave motion, which is a sign that the wave motion is generated, is generated simultaneously with the wave motion, or is different after the wave motion is generated. Any active type or passive type observing device or a similar observing device regarding the phenomenon or wave) is used. Anomalously, the dedicated receiving device may only receive the timing signal, and the reading of the additional information itself may be performed by the digital signal processing unit via the control unit in the dedicated device or the device body.

  Even when the active or passive device itself of the present invention is used as the sensing device, the additional information may be read by the digital signal processing unit 33 as well. The timing signal may be generated by a sensing device provided. If you do not know when, where, when, or when the wave is generated, the efficiency of the data acquisition operation and the beamforming process, the power saving, the memory and the storage device are improved. It is important to save (storage medium). Data acquisition and beamforming are performed based on the clock signal of the control unit 34. If the wave source is digital, it is better to be able to synchronize and the device may operate at high clock frequencies and high sampling frequencies based on the digital reception of the waves of interest. The same applies when the timing signal is an analog signal, but when the timing signal is a digital signal, synchronization may be taken in the device main body.

  The observation target is the wave itself generated by the self-emanating wave source, and the characteristics of the wave source (strength, what kind of source it is, etc.), position, time when the wave source is active, etc. May be observed. Further, as in the case where the device is an active type, the distribution of the target temperature (distribution), displacement, velocity, acceleration, strain, or strain velocity may be obtained from the wave spectrum. In addition, the characteristics of the medium in the propagation process (propagation velocity, physical properties related to waves, attenuation, scattering, transmission, reflection, refraction, etc., or their frequency dispersion) are observed, and the observation target, structure and composition of the medium, etc. May be revealed. For example, radioactive materials (isotopes in PET, etc.), materials with non-zero thermodynamic temperature, seismic sources, neural activity, astronomical observation, weather, arrivals, moving objects, communication equipment including mobile communication equipment, physical Alternatively, an object that reacts to a chemical stimulus, an electric source, a magnetic source, a radiation source, various energy sources, or the like is observed, and the observation target is not limited to these.

  Multiple different types of wave receiving transducers and sensors may be used for multi-physics or multi-genomics for fusion of measurement results and data mining. For things that function based on multiple functions and many physical properties, or things that affect the surroundings in a different way, etc. It is also performed to observe the behavior of the subject (whole body in the case of human) or local behavior newly or in detail. For example, various nerve controls (body temperature, blood flow, metabolism, etc.) that are performed in an organism for a short period of time or for a long period of time, and an effect exerted on the organism for a short period of time or a long period (radiation) It can be used to monitor artificial movements, nutrition intake, etc., and to develop artificial organs and cultured tissues that contribute to prolonging life and prolonging life, their hybrids, drugs, supplements, and their actions. It includes alternatives to various sensors that living organisms have, supplements to them, and cases where new sensors are provided. When targeting organisms, there are cases where it is required to be miniaturized and wearable, and to have a form and material that are easily familiar to the organisms. The processing contents are also various. For example, when a plurality of compression waves or shear waves arrive at the same time as mechanical waves, a dedicated analog device is used by using the mode, frequency, band, code, propagation direction, etc. Alternatively, the beamforming may be performed after separating the waves using the digital signal processing unit as in the first embodiment. When there are a plurality of wave sources of electromagnetic waves, a plurality of electromagnetic waves having different characteristics may be superposed and similarly separated. Alternatively, due to the phasing addition effect of beamforming, a highly accurate image signal may be generated even when a plurality of waves arrive (for example, when the medium is a scattering medium).

  Of course, after the beam forming is performed, the signals may be separated based on the same process. In order to obtain the effect of phasing addition, it is necessary to find the arrival direction of the wave and the position of the wave source, and steering in that direction or focusing to that position may be required. Fixed focusing is also useful in reception in addition to dynamic focusing. In order to obtain them, the center of gravity (center) frequency and the instantaneous frequency and band of the multidimensional spectrum of the wave received by the receiving aperture element array, so-called MIMO, SIMO, MUSIC, independent component analysis, code, or various parametric methods, etc. Is sometimes used. The same process may be performed after performing beamforming, but in addition, in particular, after performing beamforming at multiple positions, the wave may be observed using geometric information. . The processing method is not limited to these, and may be performed under an inverse problem approach, for example.

  For example, the propagation direction of an incoming wave is obtained based on multidimensional spectrum analysis of a received signal (past achievements of the inventor of the present application), and further, in the device of the present invention, a plurality of transducers provided at different positions are provided. Or even when the information about the propagation time cannot be obtained by using the reception effective aperture (usually, the position and distance of the wave source are calculated from the time when the wave is observed at multiple positions), the wave source is geometrically determined. It is possible to determine the position and distance. Waves can be observed not only in pulse waves or burst waves but also in continuous waves. Through any processing, when the arrival direction of the wave is known, the reception beam can be steered and focused in that direction (monostatic type or multistatic type aperture plane synthesis) and can be observed in detail. If necessary, transmission beamforming may also be performed by making the active type of the first embodiment. In those processes, always receiving the beamforming while changing the steering angle, observing the obtained image or image, the spatial resolution, the contrast, the signal strength, or the like, with emphasis on the highly probable direction, or It is also possible to identify the direction of the wave source through multidimensional spectral analysis. It may be automatically controlled.

  The super resolution may increase the resolution of the image signal. It is also described in paragraphs 0009 and 0404. In some cases, it is easy to measure the size, intensity, position, etc. of the wave source, scattering in the measurement target or medium, and the reflector. The band is always limited by the physically generated wave field, but typical super-resolution is to broaden the band by inverse filtering and restore them as the original signal source or signal. is there. In addition, waves are usually affected by frequency-dependent attenuation, may not be in focus, the wave source may be a moving body, and the intervening medium may be disturbed. . Super-resolution may be performed to correct these.

  In addition, the measurement target or the like may move during the transmission and / or reception required to generate one image signal, and it may be necessary to perform motion compensation. In many cases, the point spread function is unknown. In that case, blind deconvolution may be performed, including the case where the above signal separation processing (in particular, blind separation) is also used. The method described in paragraph 0404 and the like are known. It is desirable to evaluate the point spread function by some method and ideally obtain a coherent point spread function. It is possible.

  When the point spread function cannot be obtained when the observation is desired, for example, the point spread function may be evaluated and stored as a database when the observation is possible. One effective method of performing inverse filtering is to weight the observed spectrum so that it becomes the same as the desired spectral distribution of the signal distribution such as the point spread function or echo distribution (of course, the spectral intensity distribution). Is possible. Spectral distribution of desired signal distribution such as point spread function and echo distribution may be set through analytical or simulation, optimization, etc., and beam forming is performed under ideal parameters for the measurement target. , That may be done only once, or ensemble averaging may be performed under multiple measurements, and the measurement target phantom (calibration phantom) may be used in the same way. It may be required. For example, fixed focusing or aperture plane synthesis (Non-Patent Document 15) is performed using a power function apodization to obtain a desired high-resolution point spread function or a signal distribution such as an echo distribution, and a plane wave capable of high-speed transmission / reception. A low resolution signal (Non-Patent Document 15) obtained by performing transmission using Gaussian apodization may have a high resolution. The latter is suitable for high-accuracy measurement of high-speed motion and shear wave propagation, and it is possible to simultaneously realize that measurement and high-resolution ultrasonic imaging. Alternatively, it is possible to perform inversion using the power spectrum of the signal itself. These processes can be applied to the angular spectrum before wave number matching or the spectrum after wave number matching. That is, super-resolution can be performed using a desired point spread function, an angular spectrum or spectrum of a signal distribution such as an echo distribution, or an angular spectrum or spectrum of a received signal. In addition, in weighting, care must be taken when dividing by zero value or small spectrum, in particular, it is not effective to amplify various noises included in the received signal, and as described above, regularization (high frequency components Is suppressed), Wiener filter (suppresses the amplification of frequency components with low signal to noise ratio), singular value decomposition (discards small singular values or spectra, and does not use the signal component of the corresponding frequency). It is valid.

  Inverse filtering can also be performed in the processes of methods (1) to (7) in the above digital wave signal processing. The resolution of the image signal is increased and the effect may be obtained in terms of quantitativeness (numerical value), but the same effect may be obtained even when displayed as an image. The effect that the blurred image is restored and the image is in focus can be obtained. The inverse filtering may be performed on the incoherent signal, or is effective when applied in the state of the coherent signal, and in particular, it may be possible to understand the spatial change of the physical property distribution and the like. In some cases, super-resolution is applied to those that are superposed and those whose spectrum is frequency-divided. Applications of super-resolution are not limited to these.

  Also, a new super-resolution can be implemented. One is based on the non-linear processing described below, and the other is to image the instantaneous phase described here.

Now, the signal of the position coordinate s in the propagation direction (coordinate axis t) in the region of interest obtained using a single wave or beam
Where t = 0 represents a reference position in the t-axis direction, that is, the position of the wave source (t = 0), and δθ (t) represents a phase change caused by reflection or scattering at the position coordinate t.

Then, from this, the instantaneous angular frequency ω (t) in the propagation direction t, the instantaneous phase θ (t), and the like are obtained and imaging is performed. The propagation direction t may be directed in the front direction without steering, or may be steered to have a deflection angle, and is two-dimensional or one-dimensional even when the region of interest is three-dimensional. Sometimes. As described in Non-Patent Document 19, the propagation direction of a wave or beam can be measured with a spatial resolution (using the center of gravity of the spectrum or the instantaneous frequency), and at the same time, the frequency in that direction can also be measured. The frequency in the direction of the integration path (tangential direction) set in the spatial integration process can be calculated with high accuracy. For example, the integration path is linear in the steering direction (angle) of the wave or beam set at the time of transmission, or in the generated wave or beam similarly, but in the steering direction (angle) estimated globally. Can be taken. In addition, in order to simplify the processing, it is possible to use the nominal frequency or the frequency in that direction which is globally estimated at the same time. It is not impossible to perform the integration in the propagation direction estimated in the state having the spatial resolution, because it involves the interpolation processing of the frequency distribution, but it is not practical.

By the way, A (s) is an amplitude and represents the reflection intensity and the scattering intensity at the position coordinate t = s. For example, it can be obtained by envelope detection (square root of sum of squares of IQ signal) through quadrature detection of Expression (30-1). Or, through the Hilbert transform using the Fourier transform,
Is also generated and is obtained by the square root of the sum of the squares of Expression (30-1) and Expression (31) (Patent Document 7 and Non-Patent Document 14). The latter is particularly suitable for digital signal processing.

A complex analytic signal (Patent Document 6 or Non-Patent Document 7) is displayed using Equations (30) and (31),
Can be expressed as

In order to obtain the instantaneous phase θ (s), the instantaneous angular frequency is first obtained. As a conventional means, the method described in Patent Document 6 or Non-Patent Document 7 assumes that at the position coordinate t = s, the instantaneous frequencies at the next sampling position coordinates t = s + Δs are equal and the instantaneous phases are not equal ( δθ (t) is a phase change (that is, random) that is determined by random scattering intensity and reflectance, and changes significantly at random with respect to t),
Assuming that, the signal at the position coordinate t = s + Δs is
When the conjugate product of Equation (32) and Equation (35) is obtained,
Therefore, the instantaneous frequency at the position coordinate t = s is
It is estimated to be.

As described in Patent Document 6 and Non-Patent Document 7, noise is actually mixed in the signal r (s), and estimation is performed under the assumptions of Expression (33) and Expression (34). , The s-axis direction or the two or one directions orthogonal to the s-axis direction may be subjected to the moving average process to improve the accuracy. When this moving average processing is applied to Expression (36) and is obtained according to Expression (37)
And when applied to formula (37) itself
However, it has been confirmed that the equation (38-1) has higher accuracy in the displacement (vector) measurement.

The instantaneous frequency on which the moving average is applied may be used to detect the instantaneous frequency at each coordinate. The estimated value of the instantaneous frequency is unbiased, and in the case of digital signal processing, with respect to equation (32),
By multiplying by, the estimated value under the assumption that the instantaneous phase θ (s) is the integrated value of phase changes (that is, random) determined by random scattering intensity and reflectance.
Is obtained.

  It should be noted that instead of the instantaneous frequency obtained by the equations (38-1) and (38-2) being subjected to the moving average, the center of gravity obtained from the first moment of the spectrum (center of gravity, that is, weighted average value) The frequency (× 2π) may be used. The equation is shown in equation (S1).

  In the equation representing the observation signal, t = 0 represents the reference position in the t-axis direction, that is, the wave source position. On the other hand, the reference position t = t'in the equation (39) may also be set to t '= 0 (wave source position), and in that case, θ' (s) obtained as a distribution of position coordinates t = s Is an estimated value of the instantaneous phase [Equation (30-2)] itself represented by the integrated value of the phase change caused by reflection or scattering. The instantaneous frequency is an averaged value, and the obtained θ ′ (s) is the estimated value obtained in that situation.

In addition, due to the influence of the moving average process and the influence of the window length when obtaining the spectrum, the instantaneous frequency can be obtained from the wave source position (t = 0) to t = s' (nonzero and s is not equal). If not, with t ′ = 0, using the nominal angular frequency or the previously measured / estimated angular frequency ω ₀ ,
Equation (39) is used as Alternatively, the equation (39) may be used as t '= s' (non-zero, but not equal to s), in which case the estimated bias θ' (s) has the following bias error. It will be.

However, when estimating Δθ (s), which is the amount of change in the instantaneous phase at sampling Δs intervals, based on equations (30-2) and (34), the bias does not pose a problem. The estimation result is
Is obtained as. A conjugate product of a complex exponential function whose core is ω (s) Δs may be obtained from the equation (36). In addition, in the above formulas (34), (36), (43) and the like, the case where the phase subtraction is obtained by using the forward difference is described, but instead, the backward difference can be performed. Further, in equation (37), equation (38-1), and equation (38-2), the calculation of the differential of the phase is performed by the approximation of dividing the above phase difference by the sampling interval, but it has a high cutoff frequency. Differentiation may be performed using a differential filter. Further, various well-known integration operations including the trapezoidal rule can be performed for the integration of the estimated value of the instantaneous frequency in Expression (39).
In order to obtain the estimation result of the instantaneous phase [Expression (30-2)] that does not include the phase rotation expressed by Expression (40), the imaginary number of the analytic signal expressed by Expression (32) Arctan (inverse function of tangent) is applied to the part / real part to find the angle of the cosine (that is, the instantaneous phase including the phase rotation) in formula (30-1), and s' = s in formula (42) It is also possible to directly subtract by using the moving average of the instantaneous frequency or the phase rotation obtained by the integral calculation of the first moment of the spectrum. However, since the direct calculation result of arctan is a result of −π to π, it is necessary to perform the subtraction processing after unwrapping the result. Since the instantaneous phase including phase rotation is monotonically increasing, unwrapping may be performed by adding 2π times an integer m when the arctan result is negative. Here, m is the number of times the result of arctan observed in the beam direction or the wave propagation direction becomes negative. Like the above case, the equation (41) may be used in some cases, and the bias error represented by the equation (42) may occur. Further, in order to estimate Δθ (s), which is the amount of change in the instantaneous phase at the sampling interval Δs that does not include a bias error, the phase rotation estimated at a position separated by Δs is not included, apart from the equation (43). It is also possible to directly calculate the difference from the estimated value of the instantaneous phase by subtraction.
The image related to the phase represented by the formula (40) or the formula (43) has a wide band and is a kind of super-resolution. The phases themselves can be displayed, multiplied by a cosine or a sine function, and further weighted by an envelope. By the way, the square root of the sum of the squares of the real part and the imaginary part of the complex analytic signal for which the phase of Expression (40) is obtained is the same as that of the envelope signal. Therefore, it is preferable to image as it is without destroying the square detection, the absolute value detection, or ideally the waviness (the sign and the phase of the signal value) (a gray image or a color image can be displayed). The image mainly represents the signal intensity determined by reflection and scattering and the phase and phase change. On the other hand, if the obtained instantaneous frequency is imaged, it becomes an image showing the influence of attenuation and the like (similarly, gray and color can be displayed). Although it has been described that the Hilbert transform is performed based on the Fourier transform (Non-Patent Document 13), it goes without saying that the original Hilbert transform may be calculated. Also, if noise is mixed in the signal, the accuracy decreases, but the target real-time signal is differentiated to generate a signal with a 90 ° phase advance, and it is multiplied by -1 to calculate the imaginary component. It is also possible to calculate (the angular frequency multiplied by the differential process is the same calculation result (phase) at the neighboring position as the phase obtained by applying the inverse function of the cosine or sine signal to the original real-time signal. And the difference (so-called forward difference, backward difference, central difference, etc., multiplied by 1 and -1 to add or subtract) are calculated and divided by the distance between those positions (difference approximation). It is sufficient, and a differential filter may be applied instead of the difference approximation).
For example, when a differentiating process is performed on an arbitrary signal represented by the equation (30-1), a spatial derivative (a spatial (s) -like change) of the amplitude A (s) is smaller than the instantaneous frequency ω (s). By making a case and its assumptions, and regarding the result of the expression (30-1) and its derivative, by applying a moving average in the multidimensional including the partial derivative direction or in the partial derivative direction, the following approximation is made. To do.
The moving average process may not be performed on the signals themselves. In addition to the above calculation, ω (s) can be estimated as follows, for example. The expression (30-1 ′) is further differentiated, and under the above conditions, assumptions, and processing, and further, the case where the spatial differentiation of ω (s) is also small and the assumption is made, the approximation is performed as follows.
At that time, the moving average process may not be performed on the signals themselves. Ω ² (s) can be estimated by dividing equation (30-1 ″) by equation (30-1) and multiplying by −1. However, the estimation result of ω ² (s) may be a negative value, and it is replaced by a positive value in the multidimensional direction including the partial differential direction s, or a positive value near the partial differential direction s, or a positive value in the vicinity Interpolation approximation using only the values, median filtering, moving average processing, and combinations thereof may be performed. The median filter is particularly effective in removing a large estimation error that suddenly occurs. In addition, ω (s) obtained by applying a square root to a positive value may be subjected to a median filter or moving average processing. Ω (s) may be obtained through these processes. The imaginary number component of the analytic signal of the equation (30-1) is obtained (that is, the analytic signal is obtained) by dividing the equation (30-1 ′) by ω (s) and multiplying by −1. This second-order differential may be obtained by applying the differential filter or the difference approximation twice to the equation (30-1), or the second-order differential filter or the second-order difference approximation (using the so-called central difference, 1, -2, 1 and the product of the additions are divided by the square of the distance at those positions). In addition to this, for the differentiation, for example, a differential filter using an operational amplifier in an analog circuit may be used, or in a digital circuit or digital signal processing, a differential filter or differential calculation based on difference approximation may be performed. Since these differentiating processes are a kind of high-pass filtering, they may be processed by providing a high-frequency cutoff frequency, or a moving average process may be performed on the result of the differentiating process. Further, for the above ω (s), in order to simplify the calculation, a nominal frequency or a globally estimated frequency (such as the first moment of the spectrum) can be used instead. This detection process is significantly faster than other detection processes. This processing can also be used for envelope imaging of r (s) (the magnitude of the analysis signal may be obtained) and measurement of displacement, velocity, acceleration, strain, strain rate, temperature and the like. When performing these measurements, multiple waves or beams are used, or multiple pseudo waves or beams obtained by frequency division of the spectrum are used, and the Doppler equations derived from each of them are used in simultaneous equations. (30-1) represents the respective wave or beam, pseudo wave or beam, and each analytic signal is obtained in the same manner. Used.

Also, when the signal is a multidimensional signal and the carrier frequency exists in a plurality of orthogonal coordinate axis directions (lateral modulation), the instantaneous phase can be estimated in the same manner. As described in Non-Patent Document 19, the propagation direction of a wave or beam can be measured with a spatial resolution (using the center of gravity of the spectrum or the instantaneous frequency), and at the same time, the frequency in that direction can also be measured. The frequency in the direction of the integration path (tangential direction) set in the spatial integration process can be calculated with high accuracy. In the case of the above-mentioned one-dimensional signal, as an example, the integral path is estimated in the steering direction (angle) of the wave or beam set at the time of transmission, or in the wave or beam generated, similarly, but from the global perspective. Although it is described that the steering path (angle) is linearly taken, in this multidimensional case, the integration path can theoretically be arbitrarily set in the dimensional space. However, in actually calculating the integral, it is important to set the integration path in a state suitable for the coordinate system in which beamforming has been performed. Often used. It is also possible to use a nominal frequency or at the same time a globally estimated frequency (project to the integration path) to simplify the process. It is not impossible to perform the integration in the propagation direction estimated in the state having the spatial resolution, because it involves the interpolation processing of the frequency distribution, but it is not practical. Now, the signal in the region of interest
When, than this, the direction _{(t 1, t 2, t} 3) the instantaneous angular frequency [omega ₁ of _{(t 1, t 2, t} 3), ω 2 (t 1, t 2, t 3), ω ₃ (t ₁ , t ₂ , t ₃ )] and the instantaneous phase θ (t ₁ , t ₂ , t ₃ ), etc. are obtained for imaging. When the region of interest is two-dimensional,
Is expressed as It is processed in the same manner as the following three-dimensional time.

Incidentally, A (s ₁ , s ₂ , s ₃ ) is an amplitude and represents the reflection intensity and the scattering intensity at the position coordinates (s ₁ , s ₂ , s ₃ ). For example, it can be obtained by envelope detection (square root of sum of squares of IQ signal) through quadrature detection of equation (30′-1). Or, through the Hilbert transform using the Fourier transform,
Is generated and is also obtained by the square root of the sum of squares of Expression (30′-1) and Expression (31 ′) (Patent Document 7 and Non-Patent Document 14). The latter is particularly suitable for digital signal processing.

A complex analytic signal (Patent Document 6 or Non-Patent Document 7) is displayed using Equation (30 ′) and Equation (31 ′),
Can be expressed as

In order to obtain the instantaneous phase θ (s ₁ , s ₂ , s ₃ ), first, the instantaneous angular frequency is obtained. The usual practice, the method described in Patent Document 6 and Non-Patent Document 7, in the position coordinates _{(s 1, s 2, s} 3), for example, t ₁ the direction of the next sampling position coordinates (s ₁ + Δs _1, Suppose that the instantaneous frequencies in (s ₂ , s ₃ ) are not equal and the instantaneous phases are not (δθ (t ₁ , t ₂ , t ₃ ) is the phase change determined by random scattering intensity or reflectance (that is, random ), And changes greatly with respect to (t ₁ , t ₂ , t ₃ )),
Assuming that, the signal at the position coordinates (s ₁ + Δs ₁ ,, s ₂ , s ₃ ) is
And the conjugate product of the equation (32 ′) and the equation (35 ′) is obtained, under the assumption of the equation (33 ′) and the equation (34 ′),
Is expressed as, Accordingly, the position coordinates _{(s 1, s 2, s} 3) s 1 direction instantaneous frequency omega ₁ in _{(s 1, s 2, s} 3) are
It is estimated to be.

As described in Patent Document 6 and Non-Patent Document 7, in fact, noise is mixed in the signal r (s ₁ , s ₂ , s ₃ ), and the formula (33 ′) or the formula (34 ′) As an estimation under the assumption of, the moving average processing may be performed in the s ₁ axis direction and two directions or one direction orthogonal to the s ₁ axis direction to improve accuracy. This moving average processing is applied to the equation (36 ') and is obtained according to the equation (37').
And when applied to ω ₁ (s ₁ , s ₂ , s ₃ ) itself
However, it has been confirmed that the equation (38'-1) has higher accuracy in the displacement (vector) measurement. Instantaneous frequencies in the directions of s ₂ and s ₃ are similarly obtained by obtaining R ₂ (s ₁ , s ₂ , s ₃ ) and R ₃ (s ₁ , s ₂ , s ₃ ).

The instantaneous frequency on which the moving average is applied may be used to detect the instantaneous frequency at each coordinate. The estimated value of the instantaneous frequency is unbiased, and in the case of digital signal processing, with respect to the equation (32 ′),
By multiplying by, the instantaneous phase θ (s ₁ , s ₂ , s ₃ ) is the estimated value under the assumption that it is the integrated value of the phase change (that is, random) determined by the random scattering intensity and reflectance.
Is obtained.

  In addition, instead of the instantaneous frequency obtained by the equations (38'-1) and (38'-2), the first moment of the spectrum (center of gravity, that is, the weighted average value) is used. You may use the gravity center frequency (* 2 (pi)) calculated | required. The formula of the center of gravity in the x-axis direction, which is one axis of the three-dimensional Cartesian coordinate system, is shown in formula (S1 ″). The other directions are similarly obtained, and are also obtained in two dimensions.

The integral path c of the expression representing the observation signal is an arbitrary line from the starting point 0 to the point of interest (s ₁ , s ₂ , s ₃ ) which considers the position where the instantaneous phase is zero as the reference position. 0 represents the position of the wave source. On the other hand, the starting point of the integration path c'in the equation (39 ') may be 0 (wave source position), and in that case, position coordinates (t ₁ , t ₂ , t ₃ ) = (s ₁ , s _2, s ₃₎ of obtained as distribution _{θ '(s 1, s 2} , s 3) is the instantaneous phase [equation (30'-2)] represented by the integral value of the phase change caused by reflection and scattering themselves Is an estimated value of. The instantaneous frequency is averaged, and the obtained θ ′ (s ₁ , s ₂ , s ₃ ) is the estimated value obtained in that situation.

Also, due to the effect of the moving average process and the effect of the window length when obtaining the spectrum, the instantaneous frequency changes from the wave source position 0 to (t ₁ , t ₂ , t ₃ ) = (s ₁ ′, s ₂ ′, s ₃ ′). ) (Not the wave source position and not equal to (s ₁ , s ₂ , s ₃ )), the starting point of the integration path c ′ is set to 0, and the nominal angular frequency or pre-measurement / estimation is performed. Using the angular frequency (ω ₀₁ , ω ₀₂ , ω ₀₃ ) in each direction,
Equation (39 ′) is used as Alternatively, the starting point of the integration path c'is (t ₁ , t ₂ , t ₃ ) ＝ (s ₁ ', s ₂ ', s ₃ ') ((s ₁ , s ₂ , s ₃ In some cases, the equation (39 ′) is used, and in that case, the following bias error occurs in the estimated value θ ′ (s ₁ , s ₂ , s ₃ ).

However, for example, based on Equations (30′-2) and (34 ′), Δθ ₁ (s ₁ , s ₂ , s ₃ ) that is the amount of change in the instantaneous phase in the t ₁ axis direction at sampling Δs ₁ intervals is calculated. The bias does not matter when estimating. The estimation result is
Is obtained as. A conjugate product of a complex exponential function whose core is ω ₁ (s ₁ , s ₂ , s ₃ ) Δs ₁ may be obtained from the equation (36 ′). In addition, the estimated value of the phase change in the directions of t ₂ and t ₃ Δθ ₂ '(s ₁ , s ₂ ,, s ₃ ) Δθ ₃ ' (s ₁ , s ₂ , s ₃ ) is also the sampling interval Δs _{2 in} each direction. It can be calculated by Δs ₃ . In addition, in the above formulas (34 ′), (36 ′), (43 ′), etc., the case where the phase subtraction is obtained by using the forward difference is described, but instead, the backward difference may be performed. is there. Further, in the formulas (37 ′), (38′-1), and (38′-2), the calculation of the differential of the phase is performed by the approximation of dividing the phase difference by the sampling interval. Differentiation may be performed using a differential filter having a frequency. In addition, various well-known integration operations including the trapezoidal rule can be performed for the integration of the estimated value of the instantaneous frequency in Expression (39 ′). In order to obtain the estimation result of the instantaneous phase [Expression (30′-2)] that does not include the phase rotation expressed by Expression (40 ′), the analysis expressed by Expression (32 ′) is performed regardless of the above. Arctan (inverse function of tangent) is applied to the imaginary part / real part of the signal to find the cosine kernel (that is, the instantaneous phase including the phase rotation) in Expression (30′-1), and in Expression (42 ′) Directly using (s ₁ ', s ₂ ', s ₃ ') = (s ₁ ,, s ₂ , s ₃ ) as the moving average of the instantaneous frequency or the phase rotation obtained by the integral calculation of the first moment of the spectrum. You can also subtract. However, since the direct calculation result of arctan is a result of −π to π, it is necessary to perform the subtraction processing after unwrapping the result. Since the instantaneous phase including phase rotation is monotonically increasing, unwrapping may be performed by adding 2π times an integer m when the arctan result is negative. Here, m is the number of times the result of arctan observed in the beam direction or the wave propagation direction becomes negative. As in the above case, the equation (41 ′) may be used, or the bias error represented by the equation (42 ′) may occur. Further, in order to estimate Δθ ₁ (s ₁ , s ₂ , s ₃ ), which is the amount of change in the instantaneous phase of the sampling interval Δs _{1 in} the t ₁ direction and does not include a bias error, separately from the equation (43 ′), It is also possible to directly subtract the difference from the estimated value of the instantaneous phase that does not include the phase rotation estimated at the position separated by Δs _{1 in the} t ₁ direction. Similarly, the estimated value of the amount of change in the instantaneous phase of the sampling intervals Δs ₂ and Δs ₃ in the directions of t ₂ and t ₃ Δθ ₂ '(s ₁ , s ₂ ,, s ₃ ) Δθ ₃ ' (s ₁ ,, s ₂ , s ₃ ) can also be obtained.
The image relating to the phase represented by the formula (40 ′) or the formula (43 ′) has a wide band and is a kind of super-resolution. The phases themselves can be displayed, multiplied by a cosine or a sine function, and further weighted by an envelope. By the way, the square root of the sum of the squares of the real part and the imaginary part of the complex analytic signal for which the phase of equation (40 ′) is obtained is the same as the envelope signal. Therefore, it is preferable to image as it is without destroying the square detection, the absolute value detection, or ideally the waviness (the sign and the phase of the signal value) (a gray image or a color image can be displayed). Although it has been described that the above Hilbert transform is performed based on Fourier transform (Non-Patent Document 13), it goes without saying that the calculation of the original Hilbert transform may be applied as in the case of one dimension. Also, if noise is mixed in the signal, the accuracy will decrease, but as in the one-dimensional case, the target real-time signal is differentiated to generate a signal with a 90 ° phase advance. , -1 can also be used to calculate the imaginary number component (the angular frequency multiplied by the differential process is the phase obtained by applying the inverse function of the cosine or sine signal to the original real-time signal The difference with the same calculation result (phase) at the position (so-called front difference, rear difference, center difference, etc.) should be calculated and then corrected by dividing by the distance of those positions (difference approximation), not difference approximation. , Sometimes a differential filter is applied).
For example, when the partial differentiation process is performed on an arbitrary signal represented by the equation (30′-1) or the like, the partial differentiation is performed in one direction from s ₁ to s ₃ . Amplitude _{A (s 1, s 2,} s 3) spatial partial derivative (spatial variation) of instantaneous frequency omega ₁ of the partial derivative direction _{(s 1, s 2, s} 3) or ω ₂ (s _1, s ₂ , s ₃ ), ω ₃ (s ₁ ,, s ₂ ,, s ₃ ), which is smaller than or assumed, and the partial differential direction with respect to the formula (30′-1) and the partial differential result thereof. By performing a moving average in the included multi-dimension or in the partial differential direction, the approximation is performed as follows. For example, when partial differentiation is performed in the s ₁ direction, it is as follows.
The moving average process may not be performed on the signals themselves. For example, in the case of lateral modulation, depending on the direction, the instantaneous frequency in that direction may be lower than the instantaneous frequency in other directions. In such a case, the direction of partial differentiation can be taken in that direction. However, if it is in the steering direction, the sampling interval of the signal may be rough, and care must be taken when performing the approximate calculation. In addition to the above calculation, ω ₁ (s ₁ , s ₂ , s ₃ ) can be estimated as follows, for example. The expression (30′-1 ′) is further partially differentiated in the same direction, and under the above conditions, assumptions, and processing, further, when the spatial differentiation of ω ₁ (s ₁ , s ₂ , s ₃ ) is also small or We make an assumption and approximate as follows.
At that time, the moving average process may not be performed on the signals themselves. By dividing Expression (30′-1 ″) by Expression (30′-1) and multiplying by −1, ω ₁ ² (s ₁ , s ₂ , s ₃ ) can be estimated. However, the estimation result of ω ₁ ² (s ₁ , s ₂ , s ₃ ) may be a negative value, and in a multidimensional including the partial differential direction, or a positive value near the partial differential direction s _1. May be replaced with, or interpolation approximation using only positive values in the vicinity, median filtering, moving average processing, or a combination thereof. The median filter is particularly effective in removing a large estimation error that suddenly occurs. Further, ω ₁ (s ₁ , s ₂ , s ₃ ) obtained by applying a square root to a positive value may be subjected to a median filter or a moving average process. Through these processes, ω ₁ (s ₁ , s ₂ , s ₃ ) may be obtained. By dividing expression (30′-1 ′) by ω ₁ (s ₁ , s ₂ , s ₃ ) and multiplying by −1, the imaginary component of the analytic signal of expression (30′-1) is obtained (that is, , Analytic signal is obtained). This second-order differential may be obtained by applying a differential filter or difference approximation twice to Equation (30′-1), or by applying a second-order differential filter or second-order difference approximation (so-called central difference). May be. even when partial differentiation in the direction of each of s ₁ than the s ₂ and s _3, in the same _{way, ω 2 (s 1, s} 2, s 3) and _{ω 3 (s 1, s 2} , s 3) is Although the analytic signal is obtained, it is desirable to appropriately select the partial differential direction as described above. In addition to this, for the differentiation, for example, a differential filter using an operational amplifier in an analog circuit may be used, or in a digital circuit or digital signal processing, a differential filter or differential calculation based on difference approximation may be performed. Since these differentiating processes are a kind of high-pass filtering, they may be processed by providing a high-frequency cutoff frequency, or a moving average process may be performed on the result of the differentiating process. In addition, for the instantaneous frequency such as ω ₁ (s ₁ , s ₂ , s ₃ ) above, in order to simplify the calculation, instead of the nominal frequency or the globally estimated frequency (the first moment of the spectrum) Etc.) can also be used. This detection process is significantly faster than other detection processes. This processing is performed by envelope imaging of r (s ₁ , s ₂ , s ₃ ) (the magnitude of the analytic signal should be obtained), displacement (vector), velocity (vector), acceleration (vector), and distortion (tensor). ), Distortion rate (tensor), etc. When measuring vectors and tensors, multiple waves and beams are used, and multiple pseudo waves and beams obtained by frequency division of the spectrum are used, and Doppler equations derived from each of them are simultaneous. To obtain simultaneous equations (transverse modulation or over-determined system), in which case equation (30'-1) represents each wave or beam, pseudo wave or beam, and each analytic signal is It is similarly obtained and used. In addition, it may be similarly used for measuring temperature and the like.
When this method is used, the image mainly represents the signal intensity and phase or phase change determined by reflection or scattering. On the other hand, if the obtained instantaneous frequency is imaged, it becomes an image showing the influence of attenuation and the like (similarly, gray and color can be displayed). The presence of the above-mentioned instantaneous phase deteriorates any measurement accuracy, even if it is a minute displacement, when the above-mentioned tissue displacement measurement method based on the Doppler method or the classical measurement method is independently performed. However, the inventor of the present application has overcome this by developing a phase matching method between frames (for example, Non-Patent Document 15). Although other methods of expanding and contracting signals that represent tissue deformation have also been reported, the former phase matching method is used for high-strength and random signals in measuring tissue displacement and strain. Indispensable for measurement. Normally, blood flow is measured using a narrow band signal, but this method enables high resolution measurement and opens up highly accurate viscosity measurement and the like. It is also possible to measure multidimensional vectors and tensors.

  Further, the envelope detection is usually performed on the generated image signal, but in the frequency domain, the calculation by the angular spectrum or the conjugate product of the spectrum, which is also performed before the addition processing, is performed. Those operations related to wave number (frequency) components are also useful (one of the nonlinear processes in the present invention). In addition to the above, square detection, absolute value detection, or the like may be performed for amplitude detection. It is to be noted that what is obtained by Fourier transform from an image signal obtained by performing beamforming (that is, focusing and deflection realized by applying delay or apodization) is a spectrum, but further beamforming is performed. If so, the Fourier transform in the axial direction and in at least one lateral direction is an angular spectrum. That is, after the image signal is generated, the beam forming process may be further performed. Also, what has undergone super-resolution processing including this processing and other processing (spectral weighting, nonlinear processing on signals, inverse filtering, etc., which will be described in detail later) is used for the above coherent addition. Or in the above incoherent addition. The targets of addition are different or the same signals (they are before or after beamforming) and subjected to other processing, or the raw signals thereof. The coherent addition is suitable for wide band (higher resolution) and higher SN ratio, while the incoherent addition is suitable for reduction of speckle and higher SN ratio. In the reduction of speckles, the spatial resolution may be lowered, but the processing with super-resolution may give a high spatial resolution result without that being a problem. Basically, incoherent addition is performed on a value that has been positively detected by some kind of detection (including power-law detection), but the detection processing other than envelope detection described above This is a process in which coherence remains in the signal (at least the vibration of the wave is known). Envelope detection is also useful, but such detection with residual coherence is particularly useful as detection processing that does not impair spatial resolution. Compared with this, according to the envelope detection, the spatial resolution may be easily deteriorated.

  The operating mode may be determined by a command (signal) input to the device. In addition, the wave of the observation target (type and characteristics of wave, intensity, frequency, bandwidth, code, etc.) and propagating medium (propagation velocity, physical property value related to wave, attenuation, scattering, transmission, reflection, refraction, or , Their frequency dispersion, etc.), and the received signal may be appropriately analog-processed or digital-processed. The characteristics (intensity, frequency, bandwidth, code, etc.) of the generated image signal may be analyzed. The data obtained by the device according to the present embodiment may be used in other devices. The apparatus according to the present embodiment may be used as one of network devices, may be controlled by the control apparatus of the network system, and may be used as a control apparatus for controlling the network device. It may also be a control device that controls a locally configured network.

  When the passive device according to the present embodiment is used as an active device, the transmission transducer (or applicator) 10 is connected to the transmission unit 31 of the device body 30, and the transmitter 31a is an analog device and a trigger signal. If there is a mode in which the trigger signal is generated and applied by the control unit 34, or if the transmitter 31a is a digital device and operates according to an external clock signal, either in the device main body 30 Or a mechanism for providing a clock signal from the control unit 34 or operating the device main body 30 with the clock signal of the transmitter 31a may be provided. When transmitter 31a is a digital device, any of these mechanisms synchronize the transmit and receive clock signals. This is important when generating one image signal based on multiple transmissions. If synchronization cannot be achieved, the error may be reduced in a situation where the clock frequency and sampling frequency are high.

  As described above, arbitrary beamforming can be realized by digital processing through fast Fourier transform without performing interpolation approximation at high speed. Virtually any focusing and any steering can be performed with any aperture shaped transducer array device. In the present invention, as described in methods (1) to (7), interpolation approximation processing may be performed in wave number matching of arbitrary beam forming, and beam forming may be performed at higher speed. In order to perform highly accurate approximate wave number matching, it is necessary to appropriately oversample the received signal at the cost of an increased calculation amount. In that case, it should be noted that the number of data of the Fourier transform is increased unlike the case where the signal at an arbitrary position can be selectively generated when the interpolation approximation process is not performed. The second embodiment can be used in an ordinary apparatus as an apparatus and with respect to an operation mode (for example, an imaging mode, a Doppler mode, a measurement mode, a communication mode, etc.), and those or the above. It is not limited to.

  In the first and second embodiments described above, targeting electromagnetic waves, vibration waves (mechanical waves) including sound waves (compression waves), shear waves, shock waves, surface waves, or waves such as heat waves, Regardless of whether transmission or reception is focused, transmission or reception is steered, or transmission or reception is apodized, any beamforming is performed digitally, including the case where the coordinate system for transmission and reception is different from the coordinate system for generating the beamformed signal. It can be performed with high accuracy and high speed without performing interpolation approximation based on the processing. Not only the frame rate at the time of image display of the beamformed signal is improved, but also high spatial resolution and high contrast can be obtained in terms of image quality. Furthermore, displacement or deformation using the beamformed signal, or, If the temperature or the like is measured, the measurement accuracy will be improved. In the present invention, as described in methods (1) to (7), interpolation approximation processing may be performed in wave number matching of arbitrary beam forming, and beam forming may be performed at higher speed. In order to perform highly accurate approximate wave number matching, it is necessary to appropriately oversample the received signal at the cost of an increased calculation amount. In that case, it should be noted that the number of data of the Fourier transform is increased unlike the case where the signal at an arbitrary position can be selectively generated when the interpolation approximation process is not performed. Superposition of waves or beams that have been beamformed at high speed or spectral frequency division, or high-speed beamforming in situations where received signals of unreceived beamforming are superposed or spectral frequency division realizes various applications. To do. The application of the present invention is not limited to this. The high-speed processing has a great effect in multidimensional imaging using a multidimensional array. It should be noted that it is desirable to perform the fast Fourier transform including the dedicated fast Fourier transform or fast inverse Fourier transform in the Fourier transform or inverse Fourier transform processing performed in the above calculation algorithm. Further, the present invention is not limited to the above embodiments, and many modifications can be made within the technical idea of the present invention by a person having ordinary knowledge in the art.

  There are various objects to be measured, such as organic substances, inorganic substances, solids, liquids, gases, objects according to rheology, living things, astronomical objects, the earth, the environment, etc., and the application range is extremely wide. Contribute to non-destructive inspection, diagnosis, resource exploration, generation and manufacturing of materials and structures, monitoring of various physical and chemical restorations and treatments, application of revealed functions and physical properties, etc. In, there is a case where accuracy is required under conditions of non-invasive, minimally invasive and non-invasive without causing a large disturbance to the object to be measured. Ideally, the object may be observed in situ, in situ. In addition, the subject may be treated or repaired by the action of the wave itself, and the situation may be observed by performing beamforming on the response from the subject at that time. In addition, beamforming is performed in satellite communication, radar, sonar, etc. to save energy, realize an information-safe environment, and enable accurate communication. The present invention is also effective in normal communication including ad hoc communication devices and mobiles. It can also be applied to sensor networks. When the object is dynamic, real-time property is required, but according to the present invention, it is possible to complete the digital beam forming in a short time at high speed and with high accuracy.

<< Third Embodiment >>
In the case of waves such as electromagnetic waves, light, mechanical vibrations, sound waves, or heat waves, the behavior as waves differs depending on the frequency, bandwidth, intensity, or mode. Many kinds of various wave transducers have been developed so far, and imaging using a transmitted wave, a reflected wave, or a scattered wave of these waves is performed. For example, it is well known that ultrasonic waves having a high frequency among acoustic waves are used in nondestructive inspection, medical treatment, and sonar. Also in the radar, electromagnetic waves (microwaves, terahertz waves, infrared rays, visible light, radiation such as X-rays, etc.) having an appropriate frequency are used according to the observation target. The same applies to other waves.

  In imaging using those waves, the distribution of amplitude data obtained through quadrature detection, envelope detection, or square detection is usually displayed as a gray image or a color image in one dimension, two dimensions, or three dimensions. .. Further, in the Doppler measurement using those waves, raw coherent signals are processed (ultrasonic Doppler, radar Doppler, laser Doppler, etc.). Further, in the field of image measurement, it is well known that motion is observed using a signal made incoherent through detection (cross-correlation processing, optical flow, etc.). In medical ultrasound and sonar, imaging using physically generated harmonics, chords, and difference tones is also performed.

  Under such circumstances, the inventor of the present application is developing an ultrasonic imaging technique for differentially diagnosing cancer lesions or sclerosis lesions in human tissues. The inventor of the present application is performing high resolution and high efficiency of HIFU (High Intensity Focus Ultrasound) treatment together with high resolution of echo imaging and high precision measurement imaging of tissue displacement. They are also imaging them based on the reception of echoes during ultrasonic radiation. Such imaging is based on performing appropriate beamforming, and requires an appropriate detection method and tissue displacement measurement method.

  For example, the inventor of the present application, as a beamforming method, a lateral modulation method using a cross beam, a spectral frequency division method, a method using many cross beams, an over-determined system method, and the like, , In particular, as square wave detection in addition to quadrature detection and envelope detection as a detection method for multidimensional signals, and as a displacement vector measurement method, multidimensional autocorrelation method, multidimensional Doppler method, multidimensional cross spectrum phase gradient method, In addition, the inventors have devised a phase matching method, etc., and have reported a technique for reconstructing and imaging a (viscous) shear elastic modulus distribution and a thermophysical property distribution based on displacement and strain measurement (see Non-Patent Documents 13 and 29). ). Some of them are already in clinical use. Recent reports by the inventor of the present application include ITEC (International Tissue Elasticity Conference), IEEE Trans. on UFFC, Ultrasonics Study Group, Acoustic Imaging Study Group, etc.

  In this connection, the inventor of the present application focuses on nonlinear imaging. Non-linear imaging (so-called harmonic imaging) based on the result of physical action in the propagation process of ultrasonic waves is currently performed in medical ultrasonic waves. In the following, in particular, the application of nonlinear ultrasound to diagnosis and treatment will be described.

  Harmonic imaging is a technique in which harmonics generated during propagation are caused by the large propagation velocity of a wave component with high sound pressure intensity (which is usually explained by the large bulk elastic modulus for high intensity sound pressure). It is for imaging the wave component. In this harmonic imaging, a contrast agent (ultrasonic contrast agent) may be used in order to enhance a nonlinear effect in ultrasonic wave propagation.

  It has already a long history that its effectiveness has been clinically recognized, such as the capability of blood flow imaging of capillaries (see Non-Patent Document 21). Doppler measurement using a non-linear component (harmonic component) is also possible, and in the near future, we will report the multi-dimensional vector measurement realized by the inventor of the present application. In Non-Patent Document 22, the so-called pulse inversion method is used to separate the fundamental wave.

  Further, tissue imaging has a history of being preceded by blood flow imaging, and at first, harmonics were separated by filtering (see Non-Patent Document 23), but now, the pulse in Separated by the version method. When the transmitted signal has a wide band, the band of the fundamental wave and the harmonic wave is covered, so that the filtering method has a limit. In addition, there is a report that a multidimensional polynomial consisting of power terms is separated into a fundamental wave and a harmonic represented by each dimensional term based on the method of least squares (see Non-Patent Document 24).

  Recently, there have been reports of applying harmonic components and chords in ultrasonic microscopes (see Non-Patent Document 25) and radiation pressure imaging (see Non-Patent Document 26). Further, since the nonlinear propagation and the heat absorption are deeply related to each other, the HIFU is used by concentrating high-intensity ultrasonic waves at the focal position, including the case of causing cavitation (Non-Patent Document 27). Etc.). Also, when energy (or mode) is converted from ultrasonic waves to shear waves (for example, when sound waves obliquely enter the boundary where the acoustic impedance between soft tissue and bone changes significantly or when shear causes shear). The generated high frequency shear wave is easily absorbed by the tissue during propagation in the vicinity of the generation position (Girke).

  The contrast agent used for the purpose of enhancing the non-linear effect in HIFU treatment (see Non-Patent Document 28, etc.) is considered effective also in these respects. Regarding the treatment of cancer lesions, the inventor of the present application was the first in the world to mention about the effect of coagulating blood to occlude the feeding artery 17 years ago, and it is believed that this effect can also be obtained. .. Recently, an applicator having a frequency band similar to that of a probe for clinical diagnosis has become available at low cost, but the present inventor believes that it is necessary to develop a dedicated contrast agent. .. The inventor of the present application considers at least the fragile characteristic and the fragile characteristic to be both attractive, but recently, it is possible to use the same characteristic for diagnosis or a mixture of several kinds. is there.

  Waves are subject to attenuation during propagation, and thus the energy of the wave becomes smaller as the propagation distance increases. In addition, the diffusing wave is also affected by diffusing. In such a case, the transmitted wave, the reflected wave, or the scattered wave reflects the change in impedance, the presence of the reflector or the scatterer, and is used for imaging or Doppler measurement of them. In those imagings, it is desirable that the signal contains high frequency components and has a wide band as much as possible or within a required range, and the same is true in the Doppler measurement.

  However, normally, high-frequency signal components are strongly affected by attenuation, their energy is lost, the frequency of the signal is lowered, and the band becomes narrower as the propagation distance increases. That is, the imaging at a position far from the signal source is affected by a low signal-to-noise ratio (SN ratio) and a low spatial resolution. In Doppler measurement, the accuracy is reduced. Reducing their effects due to damping is extremely important in the engineering sense.

  In addition, if a high-frequency signal that cannot be realized with a single signal source can be generated, higher resolution imaging and highly accurate Doppler measurement will be possible. It may be possible to simply generate a high-frequency signal. In general, the influence of attenuation is strong on high-frequency components, and for example, in a microscope susceptible to the influence of attenuation, it is preferable to be able to observe as deep as possible at a high frequency. In addition, low frequency imaging or measurement using low frequency signals may be possible. Further, it may be possible to generate a low-frequency signal that cannot be realized by a single signal source. For example, the deep part of the object can be deformed at low frequencies. In medical ultrasound images, nuclear magnetic resonance images, OCT, and laser applications, deep tissue is deformed at low frequencies using a plurality of signal sources (Tissue Elasticity).

  For example, vibration is applied from multiple directions to generate a vibration wave of a lower frequency than that frequency, or multiple ultrasonic beams are crossed at their focal positions etc. to realize a low-frequency force source there. May generate low-frequency vibration waves, and these generated vibration waves may be ultrasonic waves (longitudinal waves), and those generated vibration waves may be shear waves (transverse waves). In some cases, it may be observed by ultrasonic waves. It may be possible to adjust the propagation directions of the generated waves. If these signals can be realized theoretically or on a computational basis, it may also be possible to control the waves generated. Furthermore, a detection method that can be easily implemented in a short time, which is an alternative to the normal quadrature detection, envelope detection, and square detection, is also important.

  Therefore, in view of the above points, a second object of the present invention is to enhance a high frequency component having a relatively weak intensity or a lost high frequency component in an arbitrary wave propagating from the inside of the measurement object. It is an object of the present invention to provide an imaging apparatus capable of improving spatial resolution and measurement accuracy by performing or newly generating. Further, the imaging device enhances or simulates the non-linear effect in the measurement target, newly generates it when there is no non-linear effect in the measurement target, or virtually realizes imaging. May be. A third object of the present invention is to generate a high frequency signal that cannot be realized by a single wave source. Further, a fourth object of the present invention is to realize a detection method that can be easily implemented in a short time.

  In order to solve the above problems, an imaging apparatus according to an aspect of the present invention performs (i) nonlinear processing on an arbitrary wave propagating from within a measurement target using an nonlinear device at an arbitrary position of a propagation path. And then receiving by the transducer to generate a reception signal, (ii) processing of receiving by the transducer to generate an analog reception signal and subjecting the analog reception signal to analog nonlinear processing, and (iii) a transducer A non-linear reception processing unit that generates at least one of the processes of receiving an analog reception signal to generate an analog reception signal, digitally sampling the analog reception signal, and performing digital non-linear processing on the digital reception signal; An image signal generation unit that generates an image signal representing an image to be measured based on a reception signal obtained by the reception processing unit.

  According to one aspect of the present invention, by performing non-linear processing on a signal having a frequency at which the influence of attenuation does not pose a problem in arbitrary waves propagating from the inside of the measurement object, the strength is generally relatively weak. It is possible to enhance the spatial resolution and measurement accuracy by enhancing or newly generating the high frequency component and the lost high frequency component. In addition, waves coming from signal sources of arbitrary waves such as electromagnetic waves, light, mechanical vibration, sound waves, or heat waves, and transmitted waves, reflected waves, or scattered waves of waves emitted from those signal sources. The non-linear effect in the measurement target can be enhanced by the effect of multiplication or exponentiation during wave propagation, and the processing including analog operation and digital operation of the coherent signal obtained by detecting the signal. Alternatively, similar effects can be simulated, newly generated, or virtually realized.

  For example, in imaging using a coherent signal or Doppler measurement, compared to imaging using the original signal, high-resolution imaging was realized using a wideband signal containing high-frequency components, and the original signal was used. It is possible to realize highly accurate measurement of displacement, velocity, acceleration, strain, or strain rate as compared with Doppler measurement. Further, the same processing is applied to the same problem for the incoherent signal. As the hardware, a normal device can be used. Of course, analog processing (circuit) is faster than digital processing (circuit). A computer or a device having an arithmetic function (FPGA, DSP, or the like) can be used in the case of performing calculations including higher-order calculations and in that the degree of freedom is wide.

  In particular, it is robust against the influence of attenuation in the wave propagation process, and it is also possible to generate high-frequency components that cannot be realized with a single signal source, which enables high-resolution imaging and high-precision Doppler measurement. It is also possible to generate high-frequency signals that cannot be physically realized with a single signal source. When a plurality of 100 MHz ultrasonic transducers are used, it is possible to physically generate ultrasonic waves as many times as high, and it is possible to realize a high frequency that cannot be generated by an ordinary transducer. Further, it may be possible to simply generate a high frequency signal. According to the present invention, such a high frequency can be realized by calculation. Therefore, it is possible to generate high-frequency waves and signals that cannot be physically realized. Similarly, low-frequency imaging and measurement using low-frequency signals can be realized. It is also possible to generate low frequency signals that cannot be physically realized with a single signal source. It is also possible to realize these signals theoretically or on the basis of arithmetic and control the generated waves.

  For example, in an ultrasonic microscope, a high frequency ultrasonic wave (signal) of several hundred MHz is applied to generate an ultrasonic wave having a frequency higher than a frequency determined by a sound source, and the ultrasonic wave is robust against attenuation. Therefore, an ultrasonic microscope capable of higher-resolution imaging and higher-precision Doppler measurement than usual can be realized. Also, low frequency imaging and measurement using low frequency signals can be performed. When measuring the deformability of the tissue, for example, the deep part of the target can be deformed at a low frequency. In medical ultrasound images, nuclear magnetic resonance images, OCT, laser applications, etc., deep tissue is deformed at low frequencies using multiple signal sources. The same applies to other imaging devices and Doppler devices. In addition, effects such as heating, heating, cooling, freezing, welding, heat treatment, cleaning, or repair are improved, and high resolution at that time is possible. Similar effects can be obtained with incoherent signals after various detections.

  Further, in the technical aspect of signal processing, the processing of quadrature detection and envelope detection can be facilitated. For example, when the present invention is applied to a deflected beam or a deflected wave, an IQ signal obtained by orthogonal detection with respect to all coordinate axes can be obtained, so that envelope detection becomes easy. Further, when the present invention is applied to a cross beam, an IQ signal obtained by orthogonal detection on each coordinate axis can be obtained, and therefore displacement vector, velocity vector, acceleration vector, strain tensor, Alternatively, the distortion factor tensor can be measured. Of course, in imaging, square detection can be performed as the detection processing.

  Transducer of waves arriving from signal sources of arbitrary waves such as electromagnetic waves, light, mechanical vibration, sound waves, or heat waves, and transmitted waves, reflected waves, or scattered waves of waves emitted from these signal sources. Imaging and Doppler measurement using a coherent signal obtained by detection are widely performed in radar, sonar, non-destructive inspection, diagnosis, etc., using appropriate frequencies for each medium. Further, the wave motion generated from the signal source is also applied to heating, heating, cooling, freezing, welding, heat treatment, cleaning, repair, and the like. Further, in recent years, image measurement of movements and the like using incoherent signals has come to be performed, and various imaging and measurement are performed based on image processing and signal processing. The present invention is effective in all of these, and the applicability and marketability of the present invention are very high.

  FIG. 30 is a block diagram showing a configuration example of an imaging device according to the third embodiment of the present invention. This imaging device, based on an arbitrary wave such as electromagnetic waves, light, mechanical vibrations, sound waves, or heat waves coming from a measurement target, images the measurement target, or a physical quantity such as displacement in the measurement target. It is a non-destructive measuring device.

  As shown in FIG. 30, the imaging device includes at least one transducer 110 and an imaging device body 120. The transducer 110 may be capable of generating and receiving arbitrary waves such as electromagnetic waves, light, mechanical vibrations, sound waves, or heat waves. In that case, the transducer 110 can transmit an arbitrary wave to the measurement target 1 and receive a reflected wave or a scattered wave reflected in the measurement target 1. For example, when the arbitrary wave is an ultrasonic wave, it is possible to use an ultrasonic transducer that transmits an ultrasonic wave according to a drive signal and receives the ultrasonic wave to generate a reception signal. It is well known that the ultrasonic element (PZT, polymer piezoelectric element, etc.) is different and the structure of the transducer is different depending on the application.

  Although narrow band ultrasonic waves have historically been used for blood flow measurement, the present inventor has found that in recent years, soft tissue displacements and strains (including static cases), shear waves, which have been put to practical use in recent years, have been used. We have pioneered the use of broadband transducers for (echo) imaging, including in the case of propagation (velocity) measurements. The same applies to HIFU treatment, and continuous waves are sometimes used, but the inventor of the present application is developing using a broadband device in order to realize high-resolution treatment. When high-intensity ultrasonic waves are used, the tissue may be stimulated within a range that does not produce a heating effect and a force source may be generated in the measurement target 1 as described above, and a transducer for (echo) imaging is used. Sometimes Heat treatment, force source generation, and (echo) imaging may be performed simultaneously. The same applies to other wave sources and transducers. There are contact type and non-contact type transducers, and impedance matching of each wave is appropriately performed and used.

  Alternatively, as the transducer 110, a transmitting transducer that generates an arbitrary wave and a receiving transducer (sensor) that receives the arbitrary wave may be used. In that case, the transmitting transducer transmits an arbitrary wave to the measurement target 1, and the sensor transmits the reflected wave or the scattered wave reflected in the measurement target 1 or the transmission transmitted through the measurement target 1. Can receive waves, etc.

  For example, when an arbitrary wave is a heat wave, a heat source that does not intentionally generate sunlight, lighting, metabolism in the living body, etc. may be used, but an infrared warmer, a heater, etc. Relatively stationary ones, ultrasonic transducers that transmit ultrasonic waves for heating that are often controlled according to drive signals (sometimes a force source is generated in the measurement target 1), electromagnetic wave transducers, lasers, etc. Also used. In addition, infrared sensors that receive heat waves and generate received signals, pyroelectric sensors, microwave and terahertz wave detectors, temperature sensors such as optical fibers, ultrasonic transducers (temperature dependence of ultrasonic sound velocity and volume change, etc. A change in temperature can be detected by using the property) or a nuclear magnetic resonance signal detector (the temperature can be detected by using a chemical shift of nuclear magnetic resonance). For each wave, a transducer is used that can receive it properly.

  The transducer 110 may actively generate a wave including a harmonic when actively generating the wave according to the drive signal. For example, the transducer 110 produces a wave according to the non-linear characteristics of the wave source or the circuitry of the transmitter 121 that drives it. Further, the transducer 110 may have one transmission surface or reception surface, or may have a plurality of transmission surfaces or reception surfaces. A non-linear device 111 that performs non-linear processing on the generated arbitrary wave may be provided on the transmission surface of the transducer 110. On the receiving surface of the transducer 110, a non-linear device 111 that performs non-linear processing on arbitrary waves propagating from the inside of the measurement target 1 may be provided. The non-linear device 111 does not necessarily have to be in contact with the transmission surface or the reception surface of the transducer 110, and may be provided at any position in the propagation path of any wave.

  Further, a working device 112 such as a filter (spectrometer or the like), a shield, an amplifier, or an attenuator may be provided between the measurement target 1 and the transmission surface or the reception surface of the transducer 110. When the non-linear device 111 is used, the working device 112 may be provided on both front and rear sides of the non-linear device 111. The transducer 110, non-linear device 111, and working device 112 may be separate or may be integral in combination.

  In FIG. 30, the case where the wave source is provided in the measurement target 1 is also shown, or it may be directly controllable by the control unit 133. In addition, a wave generated by the transducer 110 may be concentrated using a lens or the like, or focus transmission may be performed using a plurality of transducers 110 to generate a wave source (dynamic wave or Using a heat wave source, or a mechanical wave or electromagnetic wave, to generate a new electromagnetic wave for a magnetic substance, which may be a contrast agent, or to create a physical action or physical property between waves. Including the case of controlling the strength and propagation direction of the wave by the stimulus).

  Of course, there may be a wave source in the measurement target 1 (for example, the electrical activity of the brain or the heart becomes the current source, and the heart becomes the power source). Further, there are cases where the wave source can be controlled, cases where the wave source cannot be controlled, and the measurement target 1 is sometimes observed in situ, or the wave source itself is an imaging target or measurement target. Sometimes. Alternatively, originally, such a wave source may exist outside the measurement target 1, and may be treated in the same manner and become the measurement target. In some cases, the nonlinear device 111 or the acting device 112 may be appropriately provided between the wave source and the measurement target 1.

  Furthermore, in order to obtain a non-linear effect in the measurement target 1 or to positively enhance the non-linear effect in the measurement target 1 in at least a part of the measurement target 1, a contrast agent (non-linear enhancement) such as microbubbles is used. Agent 1a may be injected. As the contrast agent 1a, there is a case where an agent having an affinity for the target lesion, fluid, or the like in the measurement target 1 is used. As described above, a wave that is generated by a plurality of wave sources may arrive at the transducer that receives the wave.

  The transducer 110 is supplied with a drive signal from the imaging device body 120 and / or outputs a reception signal to the imaging device body 120 by wire or wirelessly. In the case of wireless, a wireless receiver and / or a wireless transmitter are provided in the transducer 110, and a wireless transmitter and a wireless receiver are also provided in the imaging device main body 120.

  In Part A, the imaging apparatus main body 120 includes a transmitter 121, a receiver 122, a filter / gain adjusting unit 123, a non-linear element 124, a filter / gain adjusting unit 125, a detector 126, and an AD (Analogue-Analog- A to-digital converter 127 and a storage device 128 may be included. Further, in Part B, the imaging apparatus main body 120 includes a reception beam former 129, a calculation unit 130, an image signal generation unit 131, a measurement unit 132, a control unit 133, a display device 134, and an analog display device 135. May be included. The control unit 133 controls each unit of the imaging device main body 120.

  When a plurality of transducers 110 are used, part A having the same number of channels as the number of transducers 110 may be provided. The case where those transducers 110 form an array will be described later. As shown in FIG. 30, when the multi-channel part A is provided, the reception signal output from the storage device 128 of the multi-channel part A may be supplied to the reception beamformer 129 of the part B. . Alternatively, each part B may be connected in series to each part A and processed independently, and in that case, the received signal output from the storage device 128 of the part A of each channel is the same for each channel. To the receive beamformer 129 of Part B of FIG. It should be noted that the plurality of transducers 110 may be related to different different types of waves, in which case the nonlinear effects of different types of waves may be observed at the same time, and not the nonlinear effects of the same wave. May observe nonlinear effects between different types of waves.

  In Part A, the transmitter 121 to the detector 126 may be configured by analog circuits, or at least part of them may be configured by digital circuits. Further, in Part B, the reception beam former 129 to the control unit 133 may be configured by a digital circuit, or a central processing unit (CPU) and software for causing the CPU to perform various processes are recorded. It may be configured with a recording medium. A hard disk, flexible disk, MO, MT, CD-ROM, DVD-ROM, or the like can be used as the recording medium. Note that at least a part of the reception beam former 129 to the control unit 133 may be configured by an analog circuit.

  The transmitter 121 includes a signal generator such as a pulser that generates a drive signal according to the trigger signal supplied from the control unit 133. The control unit 133 may control the frequency, carrier frequency, bandwidth, transmission signal strength (apodization), or the waveform or shape of a pulse wave, a burst wave, or the like. The control unit 133 may set the timing or delay time of the trigger signal for each channel. Alternatively, the timing of the trigger signal output from the control unit 133 may be fixed for all channels, and the transmitter 121 may further include a delay element that delays the trigger signal according to the delay time set by the control unit 133. ..

  The transmitter 121 causes the transducer 110 to generate an arbitrary wave by applying the generated drive signal to the transducer 110. For example, the transmitter 121 includes a drive signal amplifier (which can also serve as apodization) in order to adjust the intensity of the transmitted wave and the intensity of the generated harmonic wave, and the delay time set by the control unit 133 is set. An element may be further included. A drive signal including harmonics may be generated and used. Various waves are generated and used, such as a chirp wave, when apodization or forced vibration is performed instead of resonance. When the drive signals generated by the transmitters 121 of a plurality of channels are applied to the plurality of transducers 110, focusing and steering of the transmission beam and transmission of a plane wave can be performed by setting the delay time by the control unit 133. (A plane wave is a narrow band wave in the direction orthogonal to the propagating direction, and it is effective when the band is widened).

  Further, the transmitter 121 may further include a non-linear element (an analog device such as a transistor, a diode or a non-linear circuit, or a digital device such as a non-linear calculator) in which the non-linear effect is similarly set. A frequency, a carrier frequency, a bandwidth, an apodization, a delay, and a non-linear effect that are prepared in advance may be set, but the operator may control them via the control unit 133, and In some cases, the computing unit 130 adaptively determines and controls them according to the observation situation.

  When driving a plurality of transducers 110, the frequency and carrier frequency, bandwidth, apodization, delay element, and non-linear element of the transmitter of each channel are controlled, but set to those patterns prepared in advance. In some cases, the operator may control those patterns via the control unit 133, and in the arithmetic unit 130, those patterns may be adaptively determined and set according to the observation situation. is there.

  The receiver 122 includes, for example, an amplifier that amplifies a received signal or an attenuator (which may also function as an apodization or a filter) that attenuates the received signal, and may further include a delay element whose delay time is set by the control unit 133. Further, the receiver 122 may further include a non-linear element that produces a non-linear effect (an analog device such as a transistor, a diode, or a non-linear circuit, or a digital device such as a non-linear calculator). They may be configured similar to those of transmitter 121, including when receiving waves by multiple transducers 110. The receiver 122 amplifies the reception signal generated by the transducer 110 that has received the arbitrary wave, and outputs the amplified reception signal to the filter / gain adjustment unit 123 and the AD converter 127.

  The filter / gain adjusting unit 123 includes a filter that limits the frequency band of the received signal, or an amplifier or an attenuator that adjusts the gain of the received signal. The filter / gain adjusting unit 123 adjusts the frequency band or gain of the received signal and outputs the received signal to the non-linear element 124.

  The non-linear element 124 includes, for example, an analog device such as a transistor, a diode, or a non-linear circuit, and subjects the received signal to analog non-linear processing. This non-linear processing may be a power operation on at least one frequency component signal included in the received signal, or a multiplication operation on a plurality of frequency component signals included in the received signal ( Hall effect elements etc. can be used).

  The filter / gain adjustment unit 125 includes a filter that limits the frequency band of the reception signal, or an amplifier or an attenuator that adjusts the gain of the reception signal. The filter / gain adjusting unit 125 adjusts the frequency band or gain of the received signal and outputs the received signal to the detector 126 and the AD converter 127.

  The filter / gain adjusting units 123 and 125 and the non-linear element 124 may be set to those prepared in advance by the control unit 133, but the operator controls them via the control unit 133. In some cases, the calculation unit 130 may adaptively determine and control them according to the observation situation. When a plurality of transducers 110 are driven, they are independently controlled in each channel, but in some cases they may be set in a prepared pattern or the operator may control those patterns via the control unit 133. May be controlled, and the calculation unit 130 may adaptively determine and set those patterns in accordance with the observation situation.

  The detector 126 generates an analog image signal by performing envelope detection processing, square detection processing, or the like on the reception signal when reception beamforming is not performed, for example. Further, displacement measurement may be performed through quadrature detection. The analog display device 135 displays the image of the measurement target 1 or the wave source based on the image signal generated by the detector 126 and the measurement result.

  The AD converter 127 selects the reception signal output from the filter / gain adjustment unit 125 when analog non-linear processing is performed on the reception signal, and the receiver 122 when the analog non-linear processing is not performed on the reception signal. Select the received signal output from. The AD converter 127 converts an analog reception signal into a digital reception signal by digitally sampling the analog reception signal. The digital reception signal obtained by the AD converter 127 is output to the storage device 128. The storage device 128 is composed of, for example, a memory such as a RAM and stores the received signal.

  The reception signal stored in the storage device 128 is supplied to the reception beamformer 129. While the signal is being processed by the reception beam former 129, the signal being processed may be temporarily stored in the storage device 128 or the external storage device 140, and those signals are read out as needed. When a single or a plurality of transducers 110 are used, the reception beamformer 129 may perform separation of harmonics by a pulse inversion method, a polynomial fitting method, or the like (the same processing is performed in the arithmetic unit 130. Sometimes it will be).

  Further, when a plurality of transducers 110 are used, the reception beamformer 129 performs a reception beamforming process on the reception signals supplied from the storage devices 128 of a plurality of channels. For example, the reception beamformer 129 delays the reception signals of a plurality of channels according to the delay time set by the control unit 133 to perform phasing processing, and then adds or multiplies the reception signals to combine the reception signals, To generate a new received signal.

  Alternatively, when the receiver 122 includes a delay element, the receivers 122 of a plurality of channels may delay each reception signal according to the delay time set by the control unit 133. The reception beamformer 129 synthesizes the reception signals by performing addition or multiplication operations on the reception signals of a plurality of channels. The reception beamformer 129 may perform apodization during reception beamforming.

  In addition, by mounting a (multi-dimensional) fast Fourier transformer on the imaging apparatus main body 120 to obtain the spectrum of the received signal, filtering or beam or wave characteristics (frequency, carrier frequency, bandwidth) based on spectrum processing. , Frequency in any direction, carrier frequency, bandwidth in any direction, waveform, beam shape, steering direction, propagation direction, etc.) may be adjusted. By performing spectral frequency division (see Non-Patent Document 29), a plurality of received signals (corresponding to a plurality of different pseudo beamformings) can be obtained from a single received signal, and further non-linear processing can be performed on them. is there. These processes may be performed on the signal that has been subjected to the non-linear process.

  In this imaging device, the plurality of wave signals (those that have undergone the non-linear effect or those that have not undergone the non-linear effect) generated using a single or a plurality of transducers are stored in the storage device 128 or the external storage device 140, In the reception beam former 129 or the arithmetic unit 130, the results are read and arithmetic operations of addition (superposition, linear processing) and multiplication (non-linear processing) are performed, which may be used for imaging and various measurements. In that case, the phasing process is appropriately performed.

  The calculation unit 130 mainly performs digital nonlinear processing on the digital reception signal output from the reception beamformer 129. This non-linear processing may be a power calculation for at least one frequency component signal included in the received signal, or a multiplication calculation for a plurality of frequency component signals included in the received signal. As described above, the arithmetic unit 130 may also serve as the reception beam former 129. Including that case, while the signal is being processed, the signal being processed may be temporarily stored in the storage device 128 or the external storage device 140, and those signals are read as needed.

  Here, the transducer 110 to the working device 112, and the receiver 122 to the arithmetic unit 130 perform nonlinear processing on an arbitrary wave propagating from within the measurement target 1 or a received signal obtained by receiving the arbitrary wave. It constitutes a non-linear reception processing unit. In the non-linear reception processing unit, at least one of the non-linear device 111, the non-linear element 124, and the calculation unit 130 converts an arbitrary wave propagating from the measurement target 1 or a received signal obtained by receiving the arbitrary wave. Non-linear processing is applied to it. In other cases, a non-linear effect may be obtained as described above.

  That is, the non-linear reception processing unit performs (i) non-linear processing on the arbitrary wave propagating from the inside of the measurement target 1 using the non-linear device 111 at an arbitrary position of the propagation path, and then receives it by the transducer 110. You may perform the process which produces | generates a received signal. The nonlinear reception processing unit (ii) receives an arbitrary wave propagating from the inside of the measurement target 1 by the transducer 110 to generate an analog reception signal, and converts the analog reception signal into an analog non-linear signal, for example. A process for performing analog non-linear processing may be performed using the element 124. Further, the nonlinear reception processing unit is obtained by (iii) receiving an analog received signal by the transducer 110 for an arbitrary wave propagating from the inside of the measurement target 1 and digitally sampling the analog received signal. The digital received signal may be subjected to digital non-linear processing using, for example, the digital arithmetic unit 130. In other cases, a non-linear effect may be obtained as described above.

  The image signal generation unit 131 and the measurement unit 132 select the reception signal output from the calculation unit 130 when performing the digital nonlinear processing on the reception signal, and receive when the reception signal is not subjected to the digital nonlinear processing. The received signal output from the beam former 129 is selected.

  The image signal generation unit 131 generates an image signal representing the image of the measurement target 1 based on the reception signal obtained by the nonlinear reception processing unit. Alternatively, the image signal generation unit 131 may generate an image signal based on the received signal obtained by the non-linear processing and the received signal not subjected to the non-linear processing. Further, the image signal generation unit 131 may generate an image signal representing the image of the measurement target 1 by selectively using the received signal obtained when the non-linear processing is not performed. For example, the image signal generation unit 131 generates an image signal by performing envelope detection processing, square detection processing, or the like on the received signal. The display device 134 generates an image signal representing the image of the measurement target 1 based on the image signal generated by the image signal generation unit 131.

  The measurement unit 132 measures the displacement or the like in the measurement target 1 using at least one of the plurality of signals obtained by the non-linear processing. For example, when observing the propagation of a mechanical or electromagnetic wave, the measurement unit 132 measures the particle displacement or particle velocity caused by any wave propagation of its own wave or another wave based on the measured displacement. In that case, the image signal generation unit 131 generates an image signal representing wave propagation based on the particle displacement or particle velocity measured by the measurement unit 132. When a plurality of waves arrive, the waves may be separated in advance, or measurement may be performed through a process of separating the waves by analog processing or digital processing after reception.

  Alternatively, when observing thermodynamic wave propagation, the measuring unit 132 uses an infrared sensor, a pyroelectric sensor, a microwave or terahertz wave detector, a temperature sensor such as an optical fiber, or an ultrasonic transducer (ultrasonic transducer) when observing thermodynamic wave propagation. Temperature changes are detected using the temperature dependence of sound velocity and volume changes of sound waves), or heat waves are measured using a nuclear magnetic resonance signal detector (temperature is detected using the chemical shift of nuclear magnetic resonance) You may. In that case, the image signal generation unit 131 generates an image signal representing thermodynamic wave propagation based on the heat wave measured by the measurement unit 132. The image signal generated by the image signal generation unit 131 and the measurement data obtained by the measurement unit 132 can be stored in the external storage device 140.

  In the above, the non-linear reception processing unit obtains the result of the exponentiation operation by the non-linear processing with respect to the arbitrary wave propagating from the measurement target 1, or the non-linear processing is the exponentiation operation, so As a result of the chord, the difference tone, and the overtone, a reception signal whose frequency is higher or lower than that of the reception signal obtained when the non-linear processing is not performed may be obtained. Further, the non-linear processing may be a multiplication operation. The non-linear processing may be high-order non-linear processing, and the effect thereof may mainly result in a power operation or a multiplication operation.

  As a result, the received signal has a wider band than the received signal obtained when the non-linear processing is not performed when the arbitrary wave has a plurality of different frequency components. Alternatively, the higher-frequency received signal becomes a higher-frequency, higher spatial resolution, lower sidelobe, or higher-contrast harmonic signal than the received signal obtained when non-linear processing is not performed. . Alternatively, the low-frequency received signal becomes a signal in a band including direct current obtained by substantially orthogonally detecting a harmonic signal. The image signal generation unit 131 generates an image signal based on at least one signal obtained by the non-linear processing.

  Alternatively, a plurality of arbitrary waves propagating from the inside of the measurement target 1 may be transmitted in the measurement target 1 in a propagation direction, a steering angle, a frequency, a carrier frequency, a pulse shape, a beam shape, a frequency or a carrier frequency in any direction, Alternatively, when at least one of the bandwidths is different, the non-linear reception processing unit performs at least one of the processes (i) to (iii) on a plurality of arbitrary waves that overlap and arrive. Is also good. The image signal generation unit 131 generates an image signal based on the reception signal obtained by the nonlinear reception processing unit.

  Here, the non-linear reception processing unit passes the plurality of arbitrary waves to at least one of the analog delay device and the analog storage device as the acting device 112 before the reception of the plurality of arbitrary waves, so that a plurality of arbitrary waves are transmitted. The waves may be overlapped at each position in the measurement target 1. This is so-called aberration correction.

  In addition, the non-linear reception processing unit obtains the result of the power operation by the non-linear processing with respect to the superposition of a plurality of arbitrary waves propagating from the measurement target 1, or the non-linear processing is the power operation, Based on a plurality of arbitrary waves, as a result of chords, difference tones, and overtones, a reception signal whose frequency is higher or lower than that of the reception signal obtained when the non-linear processing is not performed may be obtained. This also provides the same effect as above. The image signal generation unit 131 generates an image signal based on at least one signal obtained by the nonlinear reception processing unit.

  Alternatively, a plurality of arbitrary waves propagating from the inside of the measurement target 1 are propagated within the measurement target 1 in a propagation direction, a steering angle, a frequency, a carrier frequency, a pulse shape, a beam shape, and a frequency or a carrier in any direction. In the case where at least one of the frequencies or the bandwidths is different, the nonlinear reception processing unit performs at least one of the above processes (i) to (iii) for a plurality of arbitrary waves that overlap and arrive. The received signal may be separated into a plurality of signals at any time after reception of the plurality of arbitrary waves by using an analog or digital device or based on analog or digital signal processing. The image signal generation unit 131 generates an image signal representing the image of the measurement target based on at least one of the plurality of signals separated by the nonlinear reception processing unit. In the non-linear operation, the multiplication effect is obtained. Further, after the analog or digital aberration correction is performed, these signals may be added again to obtain the power effect.

  Alternatively, a plurality of arbitrary waves propagating from the inside of the measurement target 1 are propagated within the measurement target 1 in a propagation direction, a steering angle, a frequency, a carrier frequency, a pulse shape, a beam shape, and a frequency or a carrier in any direction. Non-overlapping incoming waves, non-overlapping waves that have been blocked using the working device 112, and devices (analog or digital), if at least one of the frequencies or bandwidths is different. The nonlinear reception processing unit may perform at least one of the above processes (i) to (iii) on at least one of the waves separated by using analog or digital signal processing. .. The image signal generation unit 131 generates an image signal based on the reception signal obtained by the nonlinear reception processing unit.

  Here, the non-linear reception processing unit passes the plurality of arbitrary waves to at least one of the analog delay device and the analog storage device as the acting device 112 before the reception of the plurality of arbitrary waves, so that a plurality of arbitrary waves are transmitted. The waves may be overlapped at each position in the measurement target 1. This is so-called aberration correction.

  Alternatively, the non-linear reception processing unit allows the analog reception signal to pass through at least one of the analog delay device and the analog storage device, or delays the digital reception signal by a digital operation, or a digital reception signal. May be passed through a digital storage device so that a plurality of arbitrary waves overlap each other at each position in the measurement target 1.

  In addition, the non-linear reception processing unit obtains the result of the power operation by the non-linear processing for each of the plurality of arbitrary waves propagating from the inside of the measurement object 1, or the non-linear processing is the power operation, As a result of the chord, the difference tone, and the overtone, the received signal whose frequency is higher or lower than that obtained when the non-linear processing is not performed may be obtained based on each of the arbitrary waves . This also provides the same effect as above. The image signal generation unit 131 generates an image signal based on at least one signal obtained by the nonlinear reception processing unit.

  Alternatively, the non-linear reception processing unit obtains the result of the multiplication operation by the non-linear processing for each of the plurality of arbitrary waves propagating from the measurement target 1, or the non-linear processing is the multiplication operation, and thus the plurality of arbitrary waves are calculated. Based on the wave, as a result of the chord and difference tones, or overtones, it is possible to obtain a reception signal whose frequency is higher or lower than that of the reception signal obtained when non-linear processing is not performed.

  As a result, the received signal has a wider band than the received signal obtained when the non-linear processing is not performed when the plurality of arbitrary waves have a plurality of different frequency components. Alternatively, the high-frequency or low-frequency received signal has higher spatial resolution, lower side lobes, or higher contrast than the received signal obtained when non-linear processing is not performed, and at least an arbitrary 1 A signal having a band including direct current by being substantially quadrature-detected in one direction and a harmonic frequency in at least another direction. The image signal generation unit 131 generates an image signal based on at least one signal obtained by the non-linear processing.

  In the above, the image signal generation unit 131 performs an arbitrary detection process on at least one of the plurality of signals obtained by the non-linear processing, or performs an arbitrary detection process on a combination of the plurality of signals, Alternatively, an image signal may be generated by subjecting a plurality of signals to arbitrary detection processing and then superimposing the plurality of signals.

<< Fourth Embodiment >>
Next, a fourth embodiment of the present invention will be described. FIG. 31 is a block diagram showing a configuration example of an imaging device according to the fourth embodiment of the present invention and its modification. The imaging apparatus according to the fourth embodiment and its modification is an apparatus that drives a plurality of transducers 110 or a transducer array to generate a wave, or receives a wave by them to perform imaging (see FIG. 31). Indicates a transducer array), and as the constituent element, one having the same performance as the constituent element in the third embodiment can be used.

  In the imaging apparatus according to the fourth embodiment shown in FIG. 31A, a plurality of transducers 110 or transducer arrays are used as in the imaging apparatus according to the third embodiment shown in FIG. The transducer 110 or element is connected to a plurality of transmitters 121 or receivers 122, respectively. However, in the imaging device main body 120a, a plurality of transmitters 121 or receivers 122 are provided in one part A '.

  The addition processing unit adds (linear processing ), Or the multiplication processing unit performs analog processing of multiplication (non-linear processing, Hall effect element or the like is used). As a result, the reception beamforming is performed, so that the reception beamformer 129 (FIG. 30) in Part B is unnecessary.

  Then, the digital received signal obtained through the AD converter 127 is stored in the storage device 128. The part B of the imaging device main body 120a has the same structure as the third embodiment by controlling the respective parts by the control unit 133 so as to obtain all the nonlinear effects that can be realized by the third embodiment based on the received signal. Similarly, imaging and measurement imaging are performed. Note that, in FIG. 31, wiring from the control unit 133 to the receiver 122 and the like is omitted.

  Also in the fourth embodiment, similarly to the transmitter and the receiver in the third embodiment, a delay can be given to the drive signal or the reception signal of each transducer, and the focusing or steering of transmission or reception or the like can be performed. It is also possible to perform processing. In the fourth embodiment, one AD converter 127 and one storage device 128 are provided as compared with the third embodiment in which the same number of AD converters 127 and storage devices 128 as the number of channels are required. Since it is sufficient to provide the device, the device can be simplified.

  On the other hand, in the imaging apparatus according to the modification of the fourth embodiment shown in FIG. 31B, in the part A ″ of the imaging apparatus main body 120b, the transmission delay element 121a and the reception delay element 122a have the transmitter 121 and the reception delay element 122a. It is provided outside the container 122. The imaging apparatus shown in FIG. 31 (b) is different from the imaging apparatus shown in FIG. 31 (a) in that it is added to an analog reception signal that is phased or unphased in the reception delay element 122a. The processing unit performs analog processing of addition (linear processing), or the multiplication processing unit performs analog processing of multiplication (nonlinear processing), and then the signal is received by the receiver 122. Therefore, since one transmitter 121 and one receiver 122 may be provided, the device can be significantly simplified and the same non-linear effect as in the third embodiment can be obtained.

  An imaging apparatus according to the third embodiment shown in FIG. 30, an imaging apparatus according to the fourth embodiment shown in FIG. 31 (a), and an imaging according to a modification of the fourth embodiment shown in FIG. 31 (b). The device or other types of imaging devices and their components may also be used simultaneously. For example, it is possible to display each of coherent or incoherent image signals and measurement results obtained using a plurality of types of devices, display them side by side at the same time, superimpose them or multiply them. You can also display things. Basically, it is possible to target signals obtained from reception signals at the same time or the same time phase. Even in the same imaging apparatus, the same process may be performed when a plurality of image signals and measurement results are obtained using signals received at the same time or the same time phase. The target signal is an analog or digital signal after phasing, and its addition and multiplication are performed by analog processing (using a Hall effect element or the like) or digital processing (using a computer or a computing unit). .

  The imaging apparatus according to the first or fourth embodiment of the present invention uses an analog computing unit, a digital computing unit, a computer of various devices, or a device similar thereto (FPGA, DSP, etc.) to perform nonlinear computation on a signal. It is based on applying. As will be described in detail later, the non-linear operation mainly focuses on obtaining the effects of power and multiplication, but the operation itself is not limited to this and may be a high-order calculation having other non-linear characteristics. These effects can be extracted or separated through polynomial fitting, spectrum analysis, pulse inversion method, numerical calculation, signal processing, or the like. Non-linear operation may be performed not only on the signal but also on the wave, and the wave is extracted using a device (time or space, or a filter or spectroscope of those frequencies) before reception. It can also be separated. A dedicated device may be available.

  As described above, this imaging apparatus includes the transducer 110 for arbitrary waves, the transmitter 121, and the receiver 122, and also includes the nonlinear device 111, the nonlinear element 124, or the arithmetic unit 130. According to the above, a data storage device (memory, hard disk, photograph, CD-RW, or other recording medium), a display device, and the like are provided. The general-purpose devices may be assembled and configured, or the non-linear device 111, the non-linear element 124, the arithmetic unit 130, or the existing device not equipped with the non-linear device may be subjected to the non-linear processing of the present invention. Non-linear processing can also be performed by adding a device to perform.

  A pulse wave, a burst wave, a coded wave such as phase modulation, or the like is used as a wave transmitted from the transmitter 121 or the transducer 110 which is a wave source, and imaging or measurement with spatial resolution is possible. is there. However, when measurement is possible without requiring spatial resolution, this is not a limitation and continuous waves may be used.

  The generated wave is determined by the conversion characteristic of the electric signal (driving signal) into the wave in the transducer 110, and an appropriately designed device and driving signal are used. For example, in the case of light waves, various light sources (coherent or incoherent, light emitting diodes (LEDs), light mixing LEDs, (tunable wavelength) lasers, optical oscillators, etc.) are used, and in the case of sound waves, electrical sources are used as sound sources. An acoustic transducer or vibrator is used. An actuator-based vibration source is used for vibration waves, and a heat source or the like is used for heat waves. As described above, in the present embodiment, the transducer 110 that generates various kinds of waves can be used.

  The transducer 110 used includes a typical transducer in targeting the above-mentioned various waves, and it is also possible to positively use a transducer which is not normally used because it has a non-linear characteristic. Normally, in an ultrasonic element, when a high pressure is applied, an ultrasonic wave containing harmonics is generated by a nonlinear phenomenon, but the pulse inversion method is used to perform harmonic imaging to extract the nonlinear component generated in the medium. In some cases, only the signal in the fundamental wave band is used after filtering out harmonic components.

  Also in this embodiment, a nonlinear wave may be positively generated and used. That is, when a nonlinear characteristic appears during transmission, the transmitted wave is in a state of containing harmonics, but this may be effectively applied in the present invention. On the other hand, a wave that does not include a non-linear component is generated to search for a non-linear phenomenon in the measurement target.

  In addition, in a wave having a non-linear component, a non-linear phenomenon may occur in harmonics. When the transmitted wave originally contains harmonics or when there are multiple intersecting waves (frequency or carrier frequency, pulse shape, beam shape, or frequency or carrier frequency seen in each direction, or bandwidth) May be different, that is, the wave parameters other than the propagation direction and the steering angle are different). The present invention may be carried out after separation by processing or by digital processing such as those or signal processing, or the present invention may be carried out without separation. Also, in the propagation process, a shield such as an obstacle, a filter device, or a spectroscope (of time or space, or those frequencies) is given a physical stimulus to change the refractive index of the medium (optical Each of them may be received in a state where the wave is separated in advance by using a switch or the like. When the source of each wave can be controlled, each wave may be generated independently and each wave may be observed.

  Further, after the wave is generated in the transducer 110 and before the wave propagates to the measurement object, a device that directly causes a nonlinear phenomenon with respect to the wave is used to measure the wave including the nonlinear component. May be propagated to. It is also possible to use a device that causes a non-linear phenomenon after or during propagation in the measurement object. The multiplication effect may be obtained by combining waves or signals, or by mixing them.

  For example, regarding light, (i) a non-linear optical element (for example, an optical harmonic generation device used for wavelength conversion of laser light into a short wavelength region, etc.), (ii) a light mixing device, (iii) optical parametric generation , Stimulated Raman scattering, coherent Raman scattering, stimulated Brillouin scattering, stimulated Compton scattering, or devices that produce optical parametric effects such as four-wave mixing, (iv) multiphoton transitions such as ordinary Raman scattering (spontaneous emission Raman scattering) Can be used, (v) a device that causes a nonlinear refractive index change, and (vi) a device that causes an electric field-dependent refractive index change. Couplers and optical fibers can also be used effectively. Multi-point observation (multi-channel) is also possible, and it is suitable for signal processing.

  When using light, it is relevant to a wide range of fields such as optoelectronics, nonlinear optical effects, or laser engineering for the generation, control, or measurement of light. The commonly used optical device can be used as the working device 112 or the non-linear device 111, and a specially realized optical device may be used. These include optical amplifiers (photon multi-tubes, etc.), absorbers (attenuators), reflectors, mirrors, scatterers, collimators, (focus variable) lenses, deflectors, polarizers, polarization filters, ND filters, deflected beams. Splitter (separation), shield, optical waveguide (using photonic crystal, etc.), optical fiber, optical Kerr effect device, nonlinear optical fiber, optical mixing optical fiber, optical fiber for modulation, optical confinement device, optical memory, coupler (coupler) , Directional coupler, distributor, mixing distributor, spectroscope, dispersion-shifted optical fiber, bandpass filter, phase conjugator (such as degenerate four-wave mixing and photorefractive effect), optical control switch of ferroelectric semiconductor, phase The delay device, the phase correction device, the time reversal device, the optical switch, the encoding by the optical mask, etc. may be used alone or in combination. Also, this is not the case. Under optical control (wavelength conversion / switching / routing), optical node technology, optical cross connect (OXC), optical add / drop multiplexer (OADM), optical multiplexer / demultiplexer, or optical switch element is used, and the device itself May constitute an optical transmission network or an optical network, and optical signal processing may be performed.

  CCD cameras, photodiodes, mixed photodiodes, or virtual sources (also as wave sources) described herein can be used for detection. Optical signal processing includes time and space filters, correlation calculation and matched filter processing, signal extraction, heterodyne and super-heterodyne (low frequency signals can be AD and demodulated), and homodyne. In some cases, vessels are used.

  Further, in particular, regarding non-linear media, there are various kinds such as carbon disulfide, sodium vapor, semiconductors such as silicon and gallium arsenide, quantum wells, and organic dyes such as fluorescein and erythrosine. Also, for crystals of barium titanate or the like, there is also a self-pump that performs four-wave mixing without supplying a pump wave from the outside.

  Although various general-purpose devices can be used for visible light, infrared light, microwaves, terahertz waves, and other waves such as radiation, a dedicated device may be realized and used. Not only SAW, but also devices that have a relationship between a vibration system and an electromagnetic system are useful. Also, non-linear devices can be used. There are various materials that exhibit non-linearity in heat conduction, such as alumina and zirconia synthesis, solder, and layered cobalt oxide. Heat may act on optical devices and produce non-linearity, which makes it possible to broadly consider their applications.

  Although the transducer 110 is of a contact type or a non-contact type with respect to the measurement target, an impedance matching device for each wave may be necessary as an action device. A matching device may be used between the devices in the measurement space, although this is true between the devices in the apparatus and in the electric circuit. For example, gel or water is used as a matching material when observing living tissue by ultrasonic waves. In an ultrasonic microscope, the sample is usually observed on a pedestal in many cases, but an array type or mechanical scan type (an element or element array mechanically moves through a matching material such as water in a housing). In some cases, it can be easily installed on the sample (the direction can be freely determined, etc.), or it can be used as a sample as a handy type. It may also be possible to directly observe in situ or in vivo without cutting out (in vitro). Many ultrasonic microscopes are of a fixed type whose focal position is determined by a lens or the like, which is a good method especially when such an element or element array is used. Therefore, the mechanical scan is not limited to the lateral direction or the elevation direction, and may be movable in the propagation direction. An antenna is used for the RF wave, and an electrolyte gel and an electrode, or a SQUID meter is used for observing each of the biological tissue potential and the magnetic field, depending on the size of the measurement target. , A miniaturized one may be used (such as a microscope). A weak signal may not have non-linearity, and in such a case, non-linearity may be pseudo-generated or virtually generated. When the non-linear signal is weak and cannot be observed, the non-linearity is also enhanced.

  The non-linear device may be integrated with the transmitter 121 or the transducer 110, or the non-linear device may be separately assembled and used. As described above, the nonlinear device can perform the nonlinear operation on the wave itself by using the nonlinear device at an arbitrary position as well as on the signal after reception, including performing high frequency and wide band. it can.

  Further, the present invention may be applied to cases where the wave source cannot be controlled when passively observing the waves. The present invention may be applied by obtaining the signal source position and the direction of arrival, the intensity of the signal source, and the size and distribution of the signal source using various methods or devices. In some cases, the location or direction of arrival of the source is required. At that time, they may be obtained by separating the wave and signal, or the wave and signal may be separated after the signal and the source and direction of arrival of the wave are obtained, and both are requested at the same time. Sometimes. When the wave source and the direction of arrival are obtained, the accuracy of the received beamforming is improved. The signal is subjected to signal processing such as analog processing or digital processing, and for the wave motion, a filter or spectroscope of time or space or those frequencies can be used.

  When a transducer receives a wave propagating through a medium containing an object to be measured, the transducer used for transmission may also be used for reception (when observing a reflected signal). On the other hand, a transducer different from the transducer used for transmission may be used for reception. In that case, when the transmitting transducer and the receiving transducer are in the vicinity position (when observing the reflected signal) or when the transmitting transducer and the receiving transducer are at different positions (for example, observing the transmitted wave or the refracted wave) In some cases.

  The transducer 110 may have a single aperture, or a plurality of transducers 110 may be closely arranged in an array (one-dimensional array or two-dimensional array, three-dimensional array). In some cases, a sparse array or those installed at distant positions are used at the same time. There are various shapes of openings (circular, rectangular, flat, concave, convex, etc.), and their directivities are various. Some elements are integrated with openings in multiple directions, and some have multidirectional directivity at the same position. In addition to scalar measurement of electric potential, pressure, temperature, etc., there is also one that performs vector measurement of electromagnetic waves or electric field vectors. Some are polarized. Of course, even for the same wave, the material and structure of the element are diverse. Further, there are various arrangements using them, for example, there are some in which the openings are oriented in multiple directions.

  FIG. 32 is a schematic diagram showing an arrangement example of a plurality of transducers. In FIG. 32, (a1) shows a plurality of transducers 110 densely arranged in a one-dimensional array, and (b1) shows a plurality of transducers 110 sparsely present in one-dimensional array. . (A2) shows a plurality of transducers 110 densely arranged in a two-dimensional array, and (b2) shows a plurality of transducers 110 sparsely present in a two-dimensional array. (A3) shows a plurality of transducers 110 densely arranged in a three-dimensional array, and (b3) shows a plurality of transducers 110 sparsely present in a three-dimensional array.

  The beam may be generated or adjusted in an analog manner by using a lens or the like in the opening of the transducer, but may be adjusted by the above-mentioned drive signal. Further, the imaging apparatus according to the present embodiment includes a mechanical scanning device having a maximum of 6 degrees of freedom (3 degrees of translation and 3 degrees of rotation), and the mechanical scanning device has at least one transducer 110 or at least one transducer. By mechanically moving the array in at least one direction, scanning of the measurement target 1, adjustment of the focus position, and steering may be performed.

  On the other hand, when using a plurality of transducers 110, a transmitter 121 having the same number of channels as the number of transducers 110 is provided in order to generate the same number of drive signals as the number of transducers 110 to be driven. Alternatively, a delay element group is used to generate a plurality of drive signals from a limited number of generation signals, so that a desired beamforming (focusing at a desired position or steering in a desired direction) is performed. ) May be performed.

  A conventional analog or digital beamformer can also be used. The above-mentioned beam forming (including the case of only reception) may be performed in parallel processing to improve the real-time property when scanning the measurement target.

  In addition, a plurality of transducers 110 may be driven at the same time to perform a plurality of beamformings simultaneously. Alternatively, including the case where the transmitter 121 is switched and used, beam forming may be performed multiple times using different transducers 110 at different times within a time period in which signals of the same phase are allowed to be received. Mechanical scanning may be performed on the same transducer, and beam forming may be performed multiple times.

  In each beamforming, classical aperture plane synthesis may be performed, including the case of performing mechanical scanning, and ordinary delay addition (Delay-and-Summation) or delay multiplication (Delay) based on the present invention is performed. -and-Multiplication) is performed (both are monostatic type or multistatic type). At the time of transmission, a plane wave may be generated without focusing, and in that case, it is possible to observe a wide area at once in a short time. At that time, a plane wave may be steered. The wave may be received as a plane wave or may be dynamically focused (when steering during transmission, it is better to steer during reception). The plane wave is a narrow band wave in the direction orthogonal to the propagating direction, and it is effective when the band is widened.

  FIG. 33 is a diagram for explaining the form of waves when a one-dimensional transducer array is used. In FIG. 33, (a) shows focusing of a wave, and at the time of transmission or reception, the wave beam narrowed down to the focus position determined by the setting of the delay time is formed. (B) shows the steering of the wave, and at the time of transmission or reception, the wave beam deflected in the direction determined by the setting of the delay time is formed. (C) shows the transmission or reception of the plane wave, and the plane wave is formed in the direction determined by the setting of the delay time. The plane wave is a narrow band wave in the direction orthogonal to the propagating direction, and it is effective when the band is widened.

  Before the reception by the transducer 110, the waves are passed through at least one of the analog delay device and the analog storage device so that the plurality of waves are overlapped at each position in the measurement target 1. is there. In addition, an analog signal obtained after reception by the transducer 110 is passed through at least one of an analog delay device and an analog storage device, or a digitally sampled digital signal obtained after reception is delayed by digital calculation, Alternatively, a plurality of waves may be overlapped at each position in the measurement target by passing through the digital storage device. So-called phase aberration correction may be performed as described above or in connection with the above-mentioned beamforming phasing. There are various devices. For example, in the case of light, an optical fiber can be a delay line and an optical confinement device can be a delay device or a storage device.

  On the other hand, regarding the measurement target, a signal that is strongly affected by a nonlinear phenomenon as a result of propagating in the measurement target may be observed, but conversely, a nonlinear component may not be obtained. Generally, a nonlinear phenomenon is easily observed when the wave intensity is strong, and a nonlinear phenomenon is difficult to be observed when the wave intensity is weak. In any case, the present invention can be implemented. The received signal may be separated into independent signals by performing appropriate signal processing or the like to implement the present invention.

  In order to separate signals, analog devices of various waves (time or space, filters or spectroscopes of those frequencies, etc.) may be used, and analog processing or digital processing (based on signal processing) may be used. Processing for decoding the above coding, processing for obtaining the center of gravity of the spectrum through spectrum analysis, processing for obtaining the instantaneous frequency by obtaining the analysis signal, MIMO, SIMO, MUSIC, or independent signal separation processing) .. In the passive case, various methods or devices may be used to obtain and process the signal source position and direction of arrival, the signal source intensity, the signal source size and distribution, and the present invention has been implemented. The signal source position and direction of arrival may be required later. At the same time as beamforming, the signal source position and direction, the signal source intensity, and the signal source size and distribution may be required. As will be described in detail later, in some cases, non-linear processing is performed to accurately separate signals in the situation represented by harmonics or the like. Specifically, in the frequency domain, after performing high frequency and wide band (when the order is greater than 1) or low frequency and narrow band (when the order is less than 1) processing by exponentiation , It may be performed with high accuracy. Restoration of the signal after separation may be performed by using the reciprocal power of the power order used.

  FIG. 34 is a diagram showing the angle of the beam direction and the arrival direction of the wave and the center of gravity of the spectrum in the spatial domain and the frequency domain in the case of two-dimensional measurement. In FIG. 34, (a) shows the beam direction angles θ1 and θ2 of the beam 1 and the beam 2 at the point of interest (x, y) in the spatial domain. Further, (b) shows the center of gravity of the spectra of the beam 1 and the beam 2 and the instantaneous frequency (fx, fy) of the beam 1 in the frequency domain.

  Basically, the beam forming is performed in an analog manner with respect to the wave, or when using a plurality of transducers 110, the beam forming (focusing or steering) is performed. As described above, the signal may be separated and then beamformed, but the signal may be separated after the beamforming.

  Further, in the case of performing aperture plane synthesis processing, it is possible to generate focusing signals at different positions and steering signals in different directions from the same received signal set (Delay-and-Summation, or Delay based on the present invention). -and-Multiplication). The invention may also be implemented on those generated signals. The transmitter 121 and the receiver 122 may be integrated or may be separated.

  There are various nonlinear elements 124, and a diode or a transistor can be used for an electrical analog signal after being received by the transducer 110. In addition, any non-linear element that applies a non-linear phenomenon to a signal by a circuit can be used, including one applying a superconducting phenomenon. Further, it is also possible to use a nonlinear element of a distributed constant system. An appropriate one is used according to the frequency of the wave (signal). The gain of the wave or signal may be appropriately adjusted using various amplifiers and attenuators.

  The non-linear operation may be performed using a non-linear device that directly causes the non-linear phenomenon to the wave before it is received at the transducer 110. For example, regarding light, the above-mentioned (i) nonlinear optical element, (ii) light mixing device, (iii) optical parametric effect, (iv) multiphoton transition such as ordinary Raman scattering (spontaneous emission Raman scattering), (v) ) Non-linear refractive index change, or (vi) electric field dependent refractive index change can be used. Non-linear devices can be used for other waves as well. The non-linear devices may be integrated with the transducer 110, or the non-linear devices may be separately assembled and used. In addition, the non-linear phenomenon itself at the time of converting a wave into an electric signal in the transducer 110 used at the time of reception may be used.

  In any of the above cases, the wave itself may be subjected to an analog operation (non-linear processing) or the signal after reception may be subjected to an analog operation. A signal may be subjected to a non-linear operation using a computer, a computer, or a similar device (FPGA, DSP, etc.).

  Regarding the imaging apparatus according to the embodiment of the present invention, when referred to as an analog type, it means that the calculation is performed by analog processing as described above. For example, an analog signal subjected to a nonlinear effect is displayed on a cathode ray tube display or an oscilloscope (analog or analog It is displayed by a display device such as digital) and is recorded in a storage medium such as a photograph (analog or digital) or holography as necessary. Alternatively, it may be digitized through AD conversion, recorded in a memory, a hard disk, or a digital data storage medium such as a CD-RW, if necessary, and displayed using a display device.

  On the other hand, the term "digital type" includes a case where the analog signal is AD-converted after appropriate analog processing (gain adjustment or filtering) and the signal is stored in a memory or a hard disk as a recording medium. The data is stored in a data storage device (such as the above-mentioned photograph or digital recording medium) as needed, and displayed on a display device.

  In the above configuration, the received signal may include a non-linear phenomenon in the measurement target, and in that case, the effect can be enhanced by using the analog device or the digital device described above, but the non-linear component is included. For a non-received signal, it is possible to newly generate a non-linear effect, simulate the non-linear effect, or virtually realize it. In addition, the non-linear effect (harmonic component) generated in the measurement target and the non-linear component (harmonic component) generated in the signal source may be separated from the effect of the non-linear operation. Exceptionally, the above devices and signal processing may be used to separate the former two non-linear effects (non-linear components), including the case where no non-linear operation is performed.

  In the above description of the imaging apparatus, the case where a transducer (transducer) for the wave to be observed is used has been described. For example, the propagation of the vibration wave is optically observed based on laser Doppler or optical image processing. The propagation of the shear wave, which becomes dominant as a low-frequency vibration wave in human tissues, can be observed using the Doppler effect of ultrasonic waves, which are also vibration waves.

  It is also possible to optically capture the propagation of sounds such as audible sound waves and ultrasonic waves. The optical treatment generally treats electromagnetic waves and includes radiation such as X-rays. Audible sound waves may be observed using ultrasonic waves. The heat wave can also be observed by an infrared camera based on radiation, a change in sound velocity of microwaves, terahertz waves, and ultrasonic waves, a change in volume of an object, a chemical shift of nuclear magnetic resonance, or the use of an optical fiber. This is based on coherent signal processing or incoherent processing such as image processing. The cases in which the behavior of the wave of interest can be observed using other waves are not limited to those, and in any case, the measurement result is an analog signal or a digital signal. Therefore, the present invention can also be implemented for those observed waves (signals). In addition to the Doppler effect, the physical properties of the medium may be modulated by the wave of the observation target, and the wave used for sensing may be interpreted. In these, the process of detecting the wave that has undergone the Doppler effect or modulation is useful. In particular, electromagnetic waves can be applied to polarized waves to easily observe waves propagating in various directions, and also to easily grasp structures having various directions. On the other hand, sound waves are also based on divergence, which enables various measurements as described in the present specification. Radiation measurement is also important. In addition to temperature distribution measurement, various remote sensing is performed using microwaves. For example, distribution of raindrops, water, atmospheric pressure, etc. is measured by measuring scattering and attenuation. Even in such a case, it is effective to obtain a high spatial resolution by various processes such as beam forming described in the present specification, and in particular, an effect that a desired position can be observed at high speed is obtained. The effect of observing any surface, region, and space directly and at high speed can be obtained without depending on the image processing after the image is generated.

  Further, in the above description of the imaging device, the non-linear operation device for electromagnetic waves, vibrations including sound, heat waves, or signals corresponding thereto has been described, but it is possible to enhance the non-linear effect between different types of physical energy. , To simulate non-linear effects, or to virtually realize non-linear effects (that is, to produce non-linear effects except when physically, chemically, or biologically) (Including the case), in which case the signals received at different times can be received by simultaneously using the devices related to the different types of waves used, or if they are simultaneous phases. The invention can also be implemented as a basis. That is, the present invention can handle a case where a plurality of types of waves are simultaneously generated and a case where one type of waves is independently generated.

  Further, in vibrations and heat waves including electromagnetic waves and sounds, if the frequency is different, the dominant behavior is different depending on each measurement object (medium), and the name is different (it may be considered that the types are different). For example, regarding electromagnetic waves, radiation such as microwaves, terahertz waves, and X-rays exists, and regarding vibration, when human soft tissue is targeted, shear waves do not propagate as waves in the megaHz band due to the effect of attenuation. The ultrasonic waves are dominant, but at low frequencies such as 100 Hz, the incompressibility is strong, and the shear wave is dominant.

  The present invention can also enhance the non-linear effect between waves having such different behaviors, simulate the non-linear effect, or virtually realize it. In that case, the present invention can also be implemented based on signals received at different times in the case of simultaneous phases by simultaneously using a plurality of types of wave devices. Of course, phenomena such as attenuation, scattering, or reflection of those waves have dispersion characteristics, and there is a limit that they must be properly used in consideration of the SN ratio of the received signal. However, the application range of the present invention is extremely wide, including that it is possible to physically generate a high frequency component or to generate a high frequency component that cannot be captured.

  In addition, in the case of positively observing the non-linear effect in the measurement object and in the case of positively performing the non-linear processing according to the present invention, both can be switched and used, or both can be used simultaneously. Through computation, it may be possible to elucidate non-linear effects within the measurement object.

  Next, an embodiment in which the present invention is applied to an ultrasonic echo signal using the configuration of the above imaging device will be described. The generation of harmonics in the ultrasonic wave propagation process is represented by multiplication or exponentiation. In particular, chords and difference tones are represented by multiplication of waves having different propagation directions or frequencies (see Non-Patent Document 26), and harmonics are generally represented by powers of waves of the same frequency ( See Non-Patent Document 24). As a physical phenomenon, it tends to occur when the intensity of waves is high. Also, the wave distortion has the effect of increasing with propagation for high-intensity components, but during propagation it is more susceptible to attenuation than the fundamental wave. On the other hand, when the intensity is not so strong, only superposition (sum or difference) is strongly observed as the wave interference, and the lateral modulation method developed by the inventor of the present application is applied to this ( See Non-Patent Documents 13 and 29).

  FIG. 35 is a diagram showing two deflected beams used in the lateral modulation method in a two-dimensional space. In FIG. 35, the horizontal axis represents the horizontal position y and the vertical axis represents the depth position x. Here, as a typical example, there are two cases, that is, beamforming in any one direction (direction of angle θ in the drawing) and lateral modulation with any one direction as an axis (X axis). For two cases, we confirm the effect of the non-linear operation after receiving beamforming. It can be confirmed that this calculation can be easily extended to the three-dimensional space and the same effect can be obtained in the three-dimensional space. In the following, “λ” is a wavelength corresponding to the center of gravity frequency of ultrasonic waves. Further, the distance x in the depth direction and the distance y in the lateral direction are ultrasonic waves propagated at time t / 2, where t is the time until the ultrasonic wave transmitted from the origin is reflected at a certain point and returns to the origin. It represents the distance.

<0> Lateral modulation: Superposition of two beams or waves (plane waves etc.) in the angles θ ₁ and θ ₂ (simultaneous transmission / reception or superposition of respective transmission / reception)
The superposition (addition, that is, sum) of two RF echo signals is represented by the following equation.
A (x, y) cos [2π (2 / λ) (xcos θ ₁ + ysin θ ₁ )]
+ A '(x, y) cos [2π (2 / λ) (xcosθ 2 + ysinθ 2)] ··· (5 0')

Here, assuming that reflection or scattering is equal and A (x, y) = A '(x, y), a coordinate composed of the X axis in the central direction of the propagation directions of the two waves and the Y axis orthogonal thereto. The superposition of two RF echo signals at (X, Y) is represented by the following equation.
A (x, y) cos {2π (2 / λ) cos [(1/2) (θ ₂ −θ ₁ )] X}
× cos {2π (2 / λ ) sin [(1/2) (θ 2 -θ 1)] Y} ··· (5 0)
In this way, lateral modulation is realized in the (X, Y) coordinate system. The two waves may have different frequencies. For example, in the following <2> and <3>, this is subjected to non-linear processing. In the case of lateral modulation in a three-dimensional space, there are two modulation directions, and therefore at least three intersecting beams need to be generated (see Non-Patent Documents 13 and 29).

<1> Power calculation of 1 beam or 1 wave in θ direction The RF echo signal is expressed by the following equation.
A (x, y) cos [2π (2 / λ) (xcosθ ＋ ysinθ)]
In this case, for example, the square is represented by the following equation (51).
(1/2) A ² (x, y) × {1 + cos [2π (2 ・ 2 / λ) (xcosθ + ysinθ)]} (51)
In this way, the second harmonic component is generated at the same time as the DC component, and the basebanded signal is also obtained (envelope signal is also directly obtained). The calculated squared echo signal has a wider bandwidth than the spectrum of the fundamental wave due to the effect of the product of different frequencies in the band, and has a short pulse length and beam width, resulting in high spatial resolution.

As a more understandable example, for example, when the RF echo signal at the position in the depth direction x has the frequencies f ₁ and f ₂ , the squared echo signal is expressed by the following equation by the square calculation.
e _I (x; f ₁ , f ₂ ) ² = e _II (x; 0,2f ₁ , 2f ₂ , f ₁ + f ₂ , f ₁ -f ₂ )
Thus, the squared echo signal has direct current (frequency 0) and signal components of frequencies 2f ₁ , 2f ₂ , f ₁ + f ₂ and f ₁ -f ₂ .

  That is, those signals generated by the power calculation have a plurality of different frequency signal components as compared to the received wave when the wave calculation has a plurality of signal components of different frequencies, when the wave calculation has no nonlinear calculation. Is a band widened with respect to the direction having, the higher harmonics, higher spatial resolution, or lower side lobes, or higher than the waves received when non-linear calculation is not performed. A signal that has obtained at least one effect of increasing the contrast, and a signal generated in a band including direct current (basebanded signal) is a signal in which harmonics are substantially quadrature detected. Waves can be imaged based on at least one.

  When a higher-order exponentiation is calculated, a signal component having a high frequency n times that of the fundamental wave is obtained by the n-th power, and the spatial resolution is further increased. Strictly speaking, the basebanded signal is different from a signal obtained by quadrature detection of the second harmonic of the baseband signal (normal baseband signal), and the calculation result thereof includes pure DC, but the original signal is obtained regardless of the processing. A high-resolution image can be easily obtained compared to the echo image of. The DC component generated by the non-linear calculation is obtained from the intensities of high frequency, low frequency, harmonics, etc., which are simultaneously generated, and the DC component contained in the basebanded signal is basically excluded. Sometimes the calculation is simplified to remove all DC in the basebanded signal. By this processing, it may be possible to image a deeper portion as compared with the case where a direct current is included, without performing the brightness adjustment depending on the depth.

  According to the theorem of double angle or fractional angle, the harmonic signal and the low frequency signal are expressed in various forms (the four arithmetic operations of the sine wave and the cosine wave), and when necessary, the digital Hilbert transform (see Non-Patent Document 13 Can be calculated through Measured harmonics can also be used. These are obtained by calculating a nonlinear signal at each position with respect to a wave of arbitrary intensity.Unlike the nonlinear component that is physically accumulated in the propagation process and affected by attenuation, new harmonics or low It realizes frequency imaging.

<2> Calculation of Power of Lateral Modulation Echo Signal For example, the square of Expression (0) is expressed by the following Expression (52).
A (x, y) ² × cos ² {2π (2 / λ) cos [(1/2) (θ ₂ −θ ₁ )] X}
× cos ² {2π (2 / λ) sin [(1/2) (θ ₂ −θ ₁ )] Y}
= A (x, y) ² × [1 ＋ cos {2π (2 ・ 2 / λ) cos [(1/2) (θ ₂ −θ ₁ )] X}
+ Cos {2π (2 ・ 2 / λ) sin [(1/2) (θ ₂ −θ ₁ )] Y}
+ Cos {2π (2 ・ 2 / λ) cos [(1/2) (θ ₂ −θ ₁ )] X}
× cos {2π (2 ・ 2 / λ) sin [(1/2) (θ ₂ −θ ₁ )] Y}] (52)
Thus, the direct current (the above-mentioned base banded signal), two signals of the second harmonic detected in one different direction, and the lateral modulation signal of the second harmonic are obtained. Similar to <1>, higher resolution is also performed. Basebanded signals and other high-order harmonic signals can be calculated in the same manner as <1>.

As an easy-to-understand example, the cross echo signal at the position (x, y) is e ₁ ((x, y); (f ₀ , f ₁ )), and e ₂ ((x, y); (f ₀ , f ₂ )) and is symmetrical in the y direction, the squared signal of the superposition signal is represented by the following equation.
[e ₁ ((x, y); (f ₀ , f ₁ )) ＋ e ₂ ((x, y); (f ₀ , f ₂ ))] ²
= E ₁ ((x, y); (f ₀ , f ₁ )) ² +2 e ₁ ((x, y); (f ₀ , f ₁ )) e ₂ ((x, y); (f ₀ , f ₂ )) ＋ e ₂ ((x, y); (f ₀ , f ₂ )) ²
= E ₁ '((x, y); (0,0), (2f ₀ , 2f ₁ )) + e ₁₂ ' ((x, y); (2f ₀ , 0), (0,2f ₁ ), (0,2f ₂ ))
＋ e ₂ '((x, y); (0,0), (2f ₀ , 2f ₂ ))
Thus, the squared signal of the superimposed signal has frequencies (0,0), (2f ₀ , 2f ₁ ), (2f ₀ , 2f ₂ ), (2f ₀ , 0), (0,2f ₁ ), ( It can be seen that it has a signal component of 0,2f ₂ ).

  That is, those signals generated by the power calculation are harmonic signals of linearly superimposed signals (signals corresponding to intersecting waves) and basebanded signals (bandwidths including DC in at least one direction). Signal), and when the wave has a plurality of signal components of different frequencies, the band is broadened in the direction having a plurality of different frequency signal components as compared to the received wave when the non-linear operation is not performed. And the harmonic is at least one of higher frequency, higher spatial resolution, lower sidelobe, or higher contrast than the corresponding wave received when non-linear operation is not performed. A basebanded signal is a signal obtained by effecting, and a baseband signal is a signal obtained by quadrature detection or substantially quadrature detection of harmonics in each direction or a plurality of directions, and it is possible to image a wave based on at least one of those signals. it can. When the same process is applied when the intersecting waves or beams have different frequencies or when they are not symmetrical with respect to the coordinate axes, chords and difference tones can be obtained in a multidimensional space. Used for. They also work in situations where other parameters are different.

  In three-dimensional space, lateral modulation requires the generation of at least three crossed beams, as described above, but in this case, the resulting basebanded signal is a quadrature detection of harmonics of each beam as well. In addition to the above-mentioned signals (near-current signals including direct current), signals obtained by quadrature detection in only one arbitrary direction or in two arbitrary directions can be obtained. That is, since the polarities of the frequencies in the symmetrical directions are opposite to the symmetrical axis, the sum thereof becomes zero. All waves and beams may be generated symmetrically with respect to the coordinate axes, but this is not the case. Also, the frequency and other parameters may be different.

<3> Multiplying Two Waves of Lateral Modulation Echo Signal For example, since two waves in the equation (0 ′) can be treated separately, the propagation direction is x If two directions are symmetrical with respect to the axis, θ ₁ = −θ ₂ , and the multiplication (product) of the two RF echo signals is represented by the following equation (53).
A (x, y) cos [2π (2 / λ) (xcos θ ₁ + ysin θ ₁ )]
× A '(x, y) cos [2π (2 / λ) (xcos θ ₁ −ysin θ ₁ )]
= A (x, y) A '(x, y) × {cos [2π (2 ・ 2 / λ) cos θ ₁ x]
＋ cos [2π (2 ・ 2 / λ) sin θ ₁ y]} ・ ・ ・ ・ (53)
As a result, two signals of the second harmonic wave detected in different one directions are obtained. These are the signal components obtained also in equation (52).

As an easy-to-understand example, the cross echo signal at the position (x, y) is e ₁ ((x, y); (f ₀ , f ₁ )), and e ₂ ((x, y); (f ₀ , f ₂ )) and is symmetrical in the y-direction, the multiplication of the signal is represented by
e ₁ ((x, y); (f ₀ , f ₁ )) × e ₂ ((x, y); (f ₀ , f ₂ ))
= E ₁₂ '((x, y); (2f ₀ , 0), (0,2f ₁ ), (0,2f ₂ ))
Thus, multiplication of signals, the frequency _{(2f 0, 0), (} 0,2f 1), it can be seen that it has a signal component of the (0, 2f _2).

  That is, the signal generated by the multiplication operation is a basebanded signal (a signal in a band including direct current in at least one direction) for each of the linearly superimposed signals (the signals corresponding to the crossed waves), When a wave has a plurality of signal components of different frequencies, the band is broadened in the direction having the signal component of a plurality of different frequencies as compared with the wave received when the non-linear operation is not performed. The signal has at least one effect of higher frequency, higher spatial resolution, lower sidelobe, or higher contrast than the corresponding wave received when non-linear operation is not performed. It is a signal obtained by orthogonally detecting a harmonic signal in each direction or a plurality of directions, and the wave can be imaged based on at least one of the signals. When the same process is applied when the intersecting waves or beams have different frequencies or when they are not symmetrical with respect to the coordinate axes, chords and difference tones can be obtained in a multidimensional space. Used for. They also work in situations where other parameters are different.

  In three-dimensional space, the lateral modulation needs to generate at least three crossed beams as described above, but in this case, the obtained basebanded signal is only one arbitrary direction or two arbitrary directions. A quadrature-detected signal is obtained. That is, since the polarities of the frequencies in the symmetrical directions are opposite to the symmetrical axis, the sum thereof becomes zero. All waves and beams may be generated symmetrically with respect to the coordinate axes, but this is not the case. Also, the frequency and other parameters may be different.

  It should be noted that, in addition to the case where the propagation direction or steering angle of each beam or wave is different as in the above cross beam, other parameters are different, such as frequency, carrier frequency, pulse shape, beam shape, and frequency seen in each direction. The carrier frequency or bandwidth may be different. Further, unlike the case of generating two (or sometimes three) intersecting waves or beams in the two-dimensional case and the three-dimensional case in the lateral modulation, in each dimension , More waves or beams may be used. Particularly, when a plane wave, a cylindrical wave, or a spherical wave is transmitted, high-speed transmission / reception is possible, and even if a plurality of waves are used like these, it is faster than the beamforming in the case of normal imaging. In addition, even when using a focusing beam, it is possible to perform high-speed beam forming using the fast Fourier transform on the received signals that have been superimposed, so that it is possible to apply the same method, especially when multiple beams are transmitted simultaneously. It can be processed at high speed (as described above, interpolation approximation may be performed in wave number matching). It is also effective to send and receive multiple times with the same parameters and superimpose them to stabilize non-linear processing (additional averaging). Also, the same processing as above is possible for signals received when so-called pulse inversion transmission is performed, and harmonics obtained by superposition of received signals during pulse transmission with different polarities. It is possible to apply the same processing to the above, or to perform the same processing before performing the superposition. When these are superposed (that is, added), a harmonic having a frequency that is an even multiple of the frequency of the fundamental wave is obtained, but if subtraction is performed instead of addition, an odd multiple is obtained. It is also important to use these for imaging (the mere subtraction of the received signal of pulse inversion mainly obtains the third harmonic). When the superposition of harmonic signals is obtained using the present invention for a signal whose band is limited by the band of the transducer at the time of reception or by positively applying an analog or digital filter, filtering (analog or digital) ) Or by performing signal processing (analog or digital) with various superpositions and fundamental waves. Further, instead of pulse inversion, a signal having a phase difference other than 180 ° may be transmitted, but the present invention can also be applied to such a case. That is, even in a beam or wave in which at least one of the parameters is different, the same non-linear effect can be obtained and effectively used in a superposed state, a separated state, a non-superposed state, or the like. Sometimes. It can be understood that the wave or beam generated by not only the linear effect but also the nonlinear effect can be designed (parameter of wave or beam such as propagation direction) and controlled through theory or calculation.

  The harmonic signals, chords, difference tones, harmonics, etc. generated by these non-linear operations have the above-mentioned characteristics and improve the image quality of echo imaging. There is also no effect of attenuation that occurs in normal harmonic imaging. The present invention is also effective for interpreting a physically generated nonlinear signal that virtually generates a nonlinear component at each position. The present invention is also effective when it is weak and cannot be observed. Furthermore, in displacement measurement, higher frequency is welcomed, and it is expected that high-precision measurement will be possible because the rotation of the phase will be faster, but in the phantom experiment shown below, the spatial resolution becomes higher. , When the high spatial resolution was measured as it was, the noise tended to increase.

  In such a case, regularization (see, for example, Non-Patent Document 18) and the weighted least squares method and the averaging process through the above-described statistical evaluation are effective. For example, the two signals of the second harmonics detected in different one directions obtained in <2> and <3> should be used for displacement measurement in each direction by using a normal one-way displacement measurement method. You can In order to measure the displacement or displacement vector generated between different time phases, for the signal having the carrier frequency in only one arbitrary direction, the change in the instantaneous phase generated between the time phases at each of the points of interest is measured as the instantaneous frequency and the center of gravity frequency. , Or it can be divided by the nominal frequency or the like to measure the displacement in that direction, and further, the displacement vector can be synthesized based on the measurement in different directions. In the past, although it requires more calculation than the multidimensional autocorrelation method (see Non-Patent Document 13), in order to realize the displacement vector measurement using the normal one-way displacement measurement method, the digital signal of the laterally modulated echo signal is used. A demodulation method has been devised and reported (computing the product of the analytic signal and the conjugate product: see Non-Patent Document 29, etc.). According to the present invention, a laterally modulated echo signal can be demodulated with a small memory and calculation amount in each stage, and the obtained signal is a harmonic signal. When a plurality of same waves can be acquired in the same condition, noise can be averaged after the received raw signal or after the non-linear processing after the reception, or the received raw signal or It is effective to reduce it by performing non-linear processing after reception and then performing integration processing. Further, instead of power or multiplication, the square norm or inner product can be calculated, and in that case, the spatial resolution is determined by the signal length at the time of the calculation. These methods may be effective in imaging and the like other than displacement measurement.

The digital demodulation method described in Non-Patent Document 29 invented by the inventor of the present application specifically derives the phase determined only by the displacement component in each direction to obtain the displacement component in each direction. As described below, for example, when measuring a two-dimensional displacement vector (dx, dy), a difference in instantaneous phase between two temporal phases at different points in the two-dimensional region of interest is generated by two intersecting beams or waves. It is expressed as the phase of the complex autocorrelation signals expj (fxdx ＋ fydy) and expj (fxdx−fydy) by using two independent single quadrant spectrums. By calculating expj (2fxdx) and expj (2fydy) and dividing the instantaneous phase difference 2fxdx and 2fydy in each direction by the instantaneous frequencies 2fx and 2fy in each direction, the unknown displacement vector (dx, dy ). Further, in the case of measuring a three-dimensional displacement vector (dx, dy, dz), expj (fxdx + fydy + fzdz), expj (fxdx + fydy−fzdz), of complex autocorrelation signals obtained from four or at least three crossed beams or waves, It can be similarly easily obtained by using four or at least three of expj (fxdx-fydy + fzdz) and expj (fxdx-fydy-fzdz). This digital demodulation method or the non-linear calculation of <2> or <3> has a carrier frequency in each direction of the symmetry axis of any wave intersecting in any direction and the direction orthogonal thereto. Since it generates waves (waves detected in one direction or two directions), avoid waves where obstacles or shields related to those waves exist, and cross waves in that way behind them. This makes it possible to generate waves with a carrier frequency in the arbitrary direction that cannot be generated directly through obstacles or shields behind obstacles or shields, which is usually difficult. It is possible to perform imaging and displacement measurement of the rear of the. For example, when a wave having a carrier frequency in the depth direction and the lateral direction is generated through an obstacle or a shield, it is equivalent to realizing a situation in which the obstacle, the shield, etc. are watermarked from the front direction. Also, at that time, the movement of the target in an arbitrary direction can be measured. The present imaging and displacement measurement can be performed not only from the front direction of the obstacle or the shield, but also from any direction. In those cases, at least one mirror may be used to generate a reflected wave and observe the back of an obstacle or a shield. For example, a wave that is steered from the front direction of an obstacle or a shield may be generated, reflected by a mirror in the steered direction, and the wave may be crossed behind the obstacle or the shield. The wave source may exist in a direction other than the front direction. The steering angle and the carrier frequency can be used in various combinations, but considering that it is necessary to obtain the effect of the complex product or the complex conjugate, the method of solving the simultaneous equations is not restricted in terms of the combination and the amount of calculation is small.
In these digital demodulation methods or in the non-linear calculation of <2> or <3>, a frequency twice as large as the instantaneous frequency in each direction is generated. Therefore, the bandwidth is widened in advance based on the Nyquist theorem. It is necessary to perform beam forming in advance, interpolate the number of beams in space, or to widen the spectrum (data interpolation) in the frequency domain other than the signal spectrum by zero padding. These processes are also a kind of signal separation. Alternatively, in these digital demodulation methods or in the non-linear calculation of <2> or <3>, in a situation where the Nyquist theorem is satisfied for the signal before processing without widening the band in such a manner. , Each of them is also subjected to the same processing, and the difference in the instantaneous phase in each direction calculated in that case is 2fxdx, 2fydy, 2fzdz, while the instantaneous frequency fx, fy, fz in each direction is the original signal. , And multiply them by 2 to remove the difference in their instantaneous phases. There is an effect that a process for widening the band is not required, the amount of calculation is small, the speed is high, and the memory is small. Instead of double the instantaneous frequency described above, the sum of the instantaneous frequencies estimated in each wave or beam in each direction may be used. If the processing is performed in the wide band, the accuracy may be deteriorated, and the processing without the wide band is useful also in this respect. It may be subjected to regularization processing if necessary.

  In the above, some examples in which the present invention is applied to ultrasonic imaging or ultrasonic measurement have been presented. When the band of the signal component calculated and generated according to the present invention overlaps the band of another signal, they cannot be separated in the frequency domain. In that case, the pulse inversion method or the separation of multidimensional terms is used, but the inventor of the present application has previously reported that the spectrum of the superposed state is treated or divided and processed ( See Non-Patent Document 29). In the present invention, as another method of accurately separating the waves, including the case where the spectra are superposed, in order to obtain the effect of separating them in the frequency space, the non-linear processing is performed on the superposed waves as a power. In a situation where a multiplication operation is performed and the bandwidth is widened to be expressed as a harmonic, it may be separated in the frequency space. On the contrary, a high frequency signal may be lowered in frequency, or a wide band signal may be narrowed in band for display or handling. Performs high frequency and wide band (when the order is greater than 1) or low frequency and narrow band (when the order is less than 1) processing by exponentiation, and then performs with high accuracy in the frequency domain. There are times when you are told. The propagation direction of the wave is the center of gravity of the generated spectrum of the harmonic (direction in the local area, that is, there is spatial resolution, or macroscopic low spatial resolution, or no), or the instantaneous frequency from the analysis signal ( It has a spatial resolution) and can be calculated. In addition, using the order of the exponentiation performed, other parameters of the wave, such as the frequency and bandwidth of the original wave, are back-calculated and can be restored in a separated state (the power order also used to restore the signal after separation). It is easy to multiply it by the reciprocal of. In such cases, the position and direction of arrival of the signal source, the intensity of the signal source, the size and distribution of the signal source can be measured with high accuracy. Further, in the case of generating a signal having a frequency higher than the original signal, it is necessary to widen the calculable bandwidth in advance before performing the calculation. Therefore, the zero padding of the spectrum is effective without the approximation (see Non-Patent Document 29), but the sampling interval may be shortened directly in the space-time based on the interpolation approximation.

  In recent years, it has become possible to simulate nonlinear propagation at low cost. Therefore, it is possible to generate the nonlinear signal by applying the nonlinear calculation of the present invention or such a simulation technique to the non-beamforming signal (plane wave or the like) or the echo signal for aperture plane synthesis. Further, based on these, it is also possible to analyze the measured nonlinear signal based on the inverse problem approach (inverse analysis) and apply it to tissue diagnosis.

  For example, in the case of ultrasonic waves, as tissue properties of a living body, sound velocity, bulk modulus, acoustic impedance, reflection, Rayleigh scattering, backscattering, multiple scattering, or attenuation is evaluated and applied to diagnosis. Sometimes. For other waves, related phenomena and inverse analysis of physical properties are effective (Mie scattering in light, scattering in radiation, Compton scattering, etc.).

  In addition, in the treatment by heating or heating, it is necessary to clarify the heat receiving characteristics (for example, the characteristics of sound waves of high-intensity ultrasonic waves, the effect of contrast agents, etc.) and the characteristics of temperature rise of the target. In some cases, it is necessary to understand the situation in advance or in the field. However, in such cases, the calculation including the nonlinear calculation is effective. Further, in therapy, it is useful to evaluate and apply the effect based on the imaging of the nonlinear effect according to the present invention. Alternatively, echo imaging and tissue displacement measurement can be performed by using the present invention on a received signal that has been physically subjected to a nonlinear effect, separated basebanded signals, and a plurality of harmonics.

  The present invention, in addition to ultrasonic waves, electromagnetic waves, light, radiation, mechanical vibration, sound waves other than ultrasonic waves, and non-linear operations such as multiplication and exponentiation for coherent signals of arbitrary waves such as heat waves. The present invention relates to an imaging device that increases the frequency, band, or contrast of a signal by applying the above method. According to the present invention, a harmonic signal can be enhanced, simulated, or newly generated. Further, the harmonic signal can be virtually realized.

  Further, it is possible to simultaneously obtain the baseband signal and the detection signal of the harmonic signal in an arbitrary direction with a smaller calculation amount as compared with the normal detection processing. As a result, for example, higher frequency and wider band, higher contrast, or side lobe suppression can be achieved, and nonlinear imaging with a high SN ratio becomes possible. In addition, the displacement vector can be easily measured with a small amount of calculation by using the normal displacement measurement method in one direction. From the viewpoint of generating chords, difference tones, harmonics, etc., high-frequency signals and low-frequency signals cannot be obtained, including cases where the wave or beam frequency or carrier frequency, steering direction, or propagation direction is different. Yes, these may be effectively used for imaging and measurement. Through theory or calculation, not only linear effects but also waves and beams generated by nonlinear effects (wave and beam parameters such as propagation direction) can be designed and controlled.

  On the other hand, in the field of image measurement, a signal (result display is an image) made incoherent by performing various kinds of detection (including simply taking absolute values of waveforms) on a coherent signal is used to detect motion. It is also well known that observations are made. Cross-correlation processing, optical flow, or a method based on the SAD (Sum and Difference) method may be used. Further, even if the present invention is applied to an incoherent signal, it is possible to widen the band (increase the resolution). The above-mentioned high-resolution detection signal obtained by the present invention can also be used. The situation in which the data becomes dense due to the increase in bandwidth is suitable for such processing, and the accuracy of motion measurement is also improved. The above method can also be applied to a coherent signal, and broadening the band is effective for improving accuracy. That is, the present invention can be applied to arbitrary coherent signals and incoherent signals.

  In addition, according to the present invention, heating (heating, cooling, freezing, welding, repair, cancer in medical treatment of any object performed by using waves (laser, ultrasonic waves, focused intense ultrasonic waves, etc.) In heating of lesions, cryotherapy, or washing of arbitrary objects (glasses, etc.), enhancing their effects through non-linear phenomena, increasing resolution, and predicting their effects (eg, It is possible to improve the effect through the exponentiation effect at the time of heating using sound waves and the effect of multiplication as well as the addition when enhancing the effect using a cross beam.

  In heat treatment using high-intensity ultrasonic waves, harmonics are generated by the non-linear effect of the tissue, and since it is a high frequency, its absorption effect as heat energy is strong, so it is easy to understand and predict the heat generation in the tissue. It is also possible to do so. From the same point of view, transmitting a high frequency signal, a broadband signal, a harmonic wave, a superposed beam, or a crossed beam is effective for treatment. Yes, it is still easy to understand and predict. Specifically, the sound pressure shape or the point spread function can be estimated based on the evaluation of the autocorrelation function in a system that can simulate the sound field or obtain the received signal. It is also effective to evaluate the harmonic signal, or to perform a non-linear operation on the fundamental signal. The same applies to other waves.

  The present invention also obtains a non-linear effect under physical conditions in which no non-linear effect is physically obtained (for example, when intensity cannot be increased with respect to a measurement target or when high intensity cannot be obtained due to high frequency). It is also effective. On the contrary, for example, the present invention can be carried out under a condition in which a non-linear effect is enhanced by using a contrast agent such as microbubbles in ultrasonic echo imaging, displacement measurement, or treatment. The tissue is sometimes permeated into the tissue, but it is also suitable for measurement and imaging of blood in blood vessels or heart chambers. That is, the present invention can enhance the non-linear effect, can be simulated, or can be newly generated. Furthermore, the present invention can virtually realize the nonlinear effect. It is also possible to evaluate non-linear effects, as described above. Contrast agents may also be used to enhance the effects of heat treatment. The same applies to other waves.

  Further, when a high-frequency signal that cannot be realized by a single signal source is generated, higher resolution imaging and highly accurate Doppler measurement are possible. In general, the influence of attenuation is strong on high-frequency components, and for example, in a microscope susceptible to the influence of attenuation, it is preferable to be able to observe as deep as possible at a high frequency. For example, when a plurality of 100 MHz ultrasonic transducers are used, it is possible to physically generate ultrasonic waves that are twice as high as the number, and it is possible to realize a high frequency that cannot be generated by a normal transducer. Further, it is possible to simply generate a high frequency signal (chord). According to the present invention, such a high frequency can be realized by calculation. Therefore, according to the present invention, it is possible to generate high-frequency waves and signals that cannot be physically realized. Similarly, low-frequency imaging and measurement using low-frequency signals (for example, a difference tone) can be realized. It is also possible to generate low frequency signals that cannot be physically realized with a single signal source. It is also possible to realize these signals theoretically or on the basis of arithmetic and control the generated waves.

  In the following, in order to prove the effect of the present invention, experimental data, simulation results, and materials such as photographs will be described. These demonstrate the effectiveness of the present invention by performing ultrasonic echo imaging and measurement imaging through ultrasonic simulation and agar phantom experiments. INDUSTRIAL APPLICABILITY The present invention can be applied to arbitrary signals (lasers, light waves, OCT, electricity, magnetic field signals, radiation such as X-rays, heat waves, etc.) other than the ultrasonic echo method and between different signals. Is. This has applications in raw coherent signals or incoherent signals after signal processing.

  With respect to the echo data for synthesizing the aperture surface of the agar phantom disclosed in Non-Patent Document 29 (linear array type probe, 7.5 MHz), beam forming in the front direction and lateral modulation of 3.5 MHz in the lateral direction are performed. The processes <1> to <3> were performed using the respective echo signals obtained when the above procedure was performed.

  FIG. 36 is a diagram showing changes in the spectrum of the echo signal according to the embodiment of the present invention. In FIG. 36, the horizontal axis represents the horizontal frequency [MHz] and the vertical axis represents the depth frequency [MHz]. In FIG. 36, (a1) and (a2) show the spectrum of the original echo signal and the spectrum of the square of the echo signal, respectively, in the case without steering. (B1), (b2), and (b3) show the spectrum of the original echo signal, the spectrum of the square of the one-way steering echo signal, and the spectrum of the square of the transverse modulation echo signal during lateral modulation. Shown respectively. (C) shows the spectrum of the product of the cross-steering beam echo signals. From FIG. 36, the spectrum of each signal derived by the above theory can be confirmed. In any echo signal, the second harmonic spectrum is generated as a result of square or multiplication, and its bandwidth is wider than the original spectrum.

  37A to 37C are diagrams showing changes in the autocorrelation function of the echo signal according to the embodiment of the present invention. Here, the horizontal axis represents the horizontal position [mm], and the vertical axis represents the normalized autocorrelation function. FIG. 37A shows a comparison between the autocorrelation function of the original echo signal and the autocorrelation function of the second harmonic of the square of the echo signal without steering. FIG. 37B shows a comparison between the autocorrelation function of the original laterally modulated echo signal and the autocorrelation function of the second harmonic of the squared laterally modulated echo signal during lateral modulation. FIG. 37C shows the autocorrelation functions of the transverse and depth components for the product of the crossed beam echo signals and the square of the transversely modulated echo signal. Based on the autocorrelation function, the lateral profile of the sound pressure or the point spread function can be evaluated (for a central depth of the region of interest of 19.1 mm). Although omitted here, if a two-dimensional autocorrelation function is obtained for this two-dimensional echo signal, the two-dimensional distribution of the sound pressure and the point spread function can be estimated and the three-dimensional autocorrelation can be obtained for the three-dimensional echo Find a function.

  38 to 40 are diagrams showing changes in the B-mode echo image according to the embodiment of the present invention. The depth of these echo images is 10.0 mm to 28.1 mm, and the width is 20.7 mm. In the agar phantom, a columnar (10 mm in diameter) claw whose shear elastic modulus is about 3.29 times higher than that of the surroundings exists around a depth of 19 mm.

  38 to 40, (a1), (a2), and (a3) show the echo image based on the original echo signal, the echo image based on the basebanded signal, and the echo signal without steering. Each of the echo images based on the second harmonic by square is shown. When there are two images on the left and right, the image on the left is from envelope detection and the image on the right is from squared detection.

  (B1), (b2), (b3), (b4), and (b5) show the echo image based on the original laterally modulated echo signal, the echo image based on the basebanded signal, and the lateral image during lateral modulation. An echo image based on the second harmonic by the square of the directional modulation echo signal, an echo image based on the lateral component of the second harmonic by the square of the lateral modulation echo signal, and a second image by the square of the lateral modulation echo signal. Each echo image based on the depth direction component of the second harmonic is shown.

  Further, (c1) and (c2) respectively show an echo image based on the lateral component and an echo image based on the depth component of the second harmonic generated by the product of the crossed beam echo signals. In the case where a plurality of waves are present, detection of superposition of coherent signals has been reported in the past, but here, the results of superposition of detection signals are shown.

  It can be confirmed from FIGS. 37A to 37C and FIGS. 38 to 40 that the spatial resolution is increased in response to the broadening of the spectrum shown in FIG. Here, the DC of the basebanded data is not turned off. By removing the direct current or, if necessary, the extremely low frequency spectrum in the depth direction or the horizontal direction by filtering, the high- or low-intensity lines (vertical stripes) running in the vertical direction can be completely removed. Is omitted). From FIG. 37A to FIG. 37C, it can be confirmed that the side lobe is lowered. Corresponding to these, the effect of increasing the contrast can be confirmed from FIGS. 38 to 40 (note the strong scatterer and the like). Since the attenuation is not corrected in the original echo signal, the image obtained from the processed signal has a shallower signal strength at the deep position as a result of the increase in contrast due to the uncorrected signal. Extremely low compared to that of position.

  In imaging using the original signal, so-called attenuation correction in the wave propagation process is performed on the coherent signal or the incoherent signal after detection, but in this device, the original coherent signal is corrected in advance. Then, the coherent signal is subjected to non-linear processing, or the coherent signal or the incoherent signal is corrected after the non-linear processing. The correction process itself may be performed mainly on the basis of the signal strength before or after the reception beamforming or after the imaging, as in the case of the normal correction. The correction may be performed according to Lambert's law.

  In that case, an average attenuation coefficient may be used, but the attenuation coefficient at each position on the path of the wave or beam is calculated by signal processing or inverse analysis in the calculation unit 130, and the correction is performed with high accuracy. It may be implemented. That is, it may be performed adaptively or automatically. Alternatively, the operator may adjust the intensity in a predetermined range at each depth via the control unit 133 while looking at the generated image. In some cases, a selectable pattern is prepared depending on the measurement target.

  The gain adjustment is performed by the receiver 122, the amplifier / attenuator in the filter / gain adjustment unit 123 or 125, the amplifier / attenuator in the reception beamformer 129 or digital processing, or the analog processing or digital processing in the arithmetic unit 130. Be seen. In the transmitter 121, the intensity of the transmitted beam or wave may be adjusted. Further, an amplifier or an attenuator may be used as the working device 112 to adjust the intensity of the wave itself. Care should be taken because the contrast agent 1a greatly influences those decisions.

  In the square calculation (<2>) of the laterally modulated echo signal in the above experiment, the laterally detected spectrum and the second harmonic of the two signals of the second harmonic detected in one different direction. Because of the overlap of the waves, the inventor split the spectrum in the eye. The result was compared with the result of multiplication of two waves of the laterally modulated echo signal (<3>) in the autocorrelation function (see FIG. 37C), except that the harmonic frequency was slightly lowered. There was no difference.

  In addition to these experiments, displacement vector measurement, strain tensor measurement, and shear modulus reconstruction were performed using the multidimensional autocorrelation method. As a result thereof, here, FIG. 41 shows the result of displacement measurement in each direction using two second harmonic signals detected in only one different direction in <3>.

FIG. 41 is a diagram showing images of the displacement vector, strain tensor, and relative shear elastic modulus measured in the agar phantom according to the embodiment of the present invention. In a part of FIG. 41, the average value and variation (in parentheses) evaluated in the center of the pawl are also shown. Noise tended to increase as compared to the result of digital demodulation of the same laterally modulated echo data (variation in distortion in the lateral direction (y) was 3.08 × 10 ⁻³ to 9.52 × 10 ^{3. -3} ), the spatial resolution is doubled, and the regularization of the shear modulus reconstruction improves the accuracy (improved from 3.37 to 3.23).

  Although the result is omitted here, as described in paragraph 0629, as described in paragraph 0629, a large number of waves and beams are generated and nonlinear processing is performed in a superposed state, and non-linear processing is performed in a non-superposed state. May be overlapped after applying. In addition, as described elsewhere, a non-linear process may be performed on a raw reception signal that has not been subjected to beamforming (such as transmission beamforming only or aperture plane synthesis). A plurality of waves or beams generated under the same wave or beam forming parameters may be processed, but waves or beams generated under different parameters may be processed.

Regarding the resolution enhancement, the super-resolution in the above linear model is effective, and those super-resolutions may be used for such a plurality of waves and beams. That is, individual waves or beams that are not superposed may be super-resolution-superimposed, or super-resolution may be superposed in the superposed state. In some cases, both may be mixed and processed. In some cases, noise is reduced by superimposing (arithmetic mean) under the same parameter. A significantly higher spatial resolution can be realized for the original signal (including the case of harmonics). Although various super-resolutions have been described, for example, as described in paragraph 0361, when inverse filtering is performed using a spectrum of a signal distribution such as a desired point spread function or echo distribution as a target, the displacements described in paragraphs 0373 to 0397 are described. As described with the measurement, the Wiener filter can be applied and weighted for imaging the signal itself. Among them, for example, based on the Wiener filter used in the formula (A12 ′) or the formula (A13 ′), Inverse filter when using weights (excluding the square norm of the first signal spectrum)
However, each of Hp (ωx, ωy, ωz) and G (ωx, ωy, ωz) is the spectrum of the signal to be processed and the target signal.
Weighted by the norm of
However, PWpn (ωx, ωy, ωz) and PWps (ωx, ωy, ωz) are power spectra of noise and signal, respectively. q is an arbitrary positive value.

Can be used for processing. Similarly, in other super-resolutions in the linear model described above, it is possible to suppress the amplification of noise by applying the Wiener filter. When the norm itself of (AA1) is applied without using the Wiener filter, ε (<1) times the norm (maximum norm, L ₂ norm, L ₁ norm, etc.) of the signal spectrum Hp (ωx, ωy, ωz). In some cases, only the spectrum of the frequency having the above spectrum is processed (the spectrums of other frequencies are set to zero). In these, irregularly, instead of the norm of (AA1), (AA1) itself may be used, and the phase may be adjusted. In that case, Gp (ωx, ωy, ωz) often has the phase information of the measurement target.
In addition, these weighting processes may be performed in blind deconvolution. In addition, including the case where whitening is performed by inverse filtering using the point spread function or the system transfer function obtained separately, the case where the point spread function or the system transfer function is conjugated, and the case where the conjugate of the formula (AA1) is applied, These weighting processes are also useful when they are performed before or after beam forming (a state of only transmitting beam forming or a received signal obtained for aperture plane synthesis). Particularly, in inverse filtering, regularization may be performed.

    The above non-linear processing may be performed on the signal subjected to super-resolution under such a linear model. Further, the resolution can be increased and the contrast can be increased. As a result of the super-resolution obtained under the linear model, the original (including the case where it is a harmonic, the same applies below) signals are super-resolved, and those super-resolved signals are The objects to be processed include a plurality of objects existing and superposed, a plurality of originals superposed and super-resolved, and a mixture of these processed. In addition, there may be a plurality of original signals, each of which is super-resolved under a linear model and subjected to non-linear processing to be superimposed. Sometimes they are mixed and processed.

  In addition, as described above, the non-linearly processed signal may be subjected to super-resolution performed by a linear model. Although the resolution is increased, the contrast may be reduced. As a result of super-resolution obtained by non-linear processing, the original (including the case where it is a harmonic) signal is super-resolved, and multiple super-resolved signals are present and superposed. The processed object is a processed image, a super-resolution image obtained by superimposing a plurality of originals, a mixed image thereof, and the like. In addition, there are cases where a plurality of original signals exist, each of which is super-resolved by non-linear processing, and each of which is subjected to super-resolution performed by a linear model and superposed. Sometimes they are mixed and processed.

In addition, when performing these non-linear processes on a plurality of signals (a signal representing a beam or a wave, which is not limited to a fundamental wave and may be a harmonic wave) at the same position of interest, the directivity of the aperture or If the original signal itself before processing has different intensities due to the influence of scattering or attenuation (including the case where it depends on the frequency) on the target, the difference may be emphasized. Once generated, it can be noticeable. This difference may be positively imaged or may be quantitatively confirmed in the spectral image (in some cases, their frequency characteristics may be emphasized and confirmed). On the other hand, in order to reduce the difference and perform imaging, a process of weighting a signal energy or a spectrum of a specific frequency may be performed before or after the non-linear process to perform imaging. The plurality of signals may be superimposed and imaged. The spectrum or energy of the signal may be evaluated in a local region including the position of interest, or may be evaluated in the entire region of interest. Of course, regardless of whether or not the non-linear processing is performed, the weighting may be similarly performed in the linear superposition processing.
Further, although the signal strength becomes weaker in the distance direction due to the influence of attenuation in the propagation process and reflection / scattering, for example, the degree of attenuation of the plane wave is weaker than that at the time of focusing. When non-linear processing is performed, the higher the order, the more the effect is emphasized. Therefore, as described above, the signal strength may be corrected before or after the non-linear processing (may be corrected even when the non-linear processing is not performed). It is processed before or after the detection.
There are various other types of super-resolution, and at least one of them may be used in combination, applied to the same or different signals, coherently added, and used. In addition, they may be incoherently added, and speckle may be reduced. Incoherent addition through super-resolution may not reduce the spatial resolution as described above.
Further, in each of those super-resolution processings, spatially non-uniform addition may be performed depending on the signal strength, the SN ratio, and the spatial resolution. That is, the parameters of each method may be variable depending on those at each position. The case of processing the spectrum is as described above. For example, in the case of nonlinear processing, the order of power or the number of multiplications is used. When the coherent signal and the incoherent signal are added, the number of additions, the weighting value, and the like are used. Of course, it may be processed spatially uniformly.
As a result of the high contrast achieved by the non-linear processing, the scatterers and reflectors in the tissue may be visualized remarkably well, and if the power order or the number of multiplications is increased, the signal strength (gray image is displayed). In this case, the effect that the difference in the brightness) becomes remarkable may be obtained. For example, it may be easier to capture post-necrotic calcification of biological tissue. In addition, for example, coloring may be performed depending on those signal intensities, and the images may be displayed by being superimposed on a normal gray image, a Doppler image, a power Doppler image, a contrast image, or the like. The processing may be performed after the intensity of the signal distribution is corrected. For example, nonlinear processing is performed after correction to make the intensity of a signal (before or after detection) received from within the region of interest spatially uniform, and the scattered intensity distribution, the scattered intensity of a plurality of scatterers, or the reflected intensity distribution, The level of the reflection intensity of the plurality of reflectors may be visualized. Processing may be performed for the purpose of counting the number of reflectors and scatterers. If a plane wave, a spherical wave, or a cylindrical wave is used in addition to the focus beam and aperture plane synthesis, the spatial resolution is low, and in such a case, various super-resolutions such as nonlinear processing are useful, In particular, when non-linear processing is performed, scattered waves and reflected waves may be outstandingly visualized at their generation positions. For example, when these cross waves are generated, a cross-type waveform is emphasized and displayed at the scatterer position as a scattered wave.

  Also, the power or multiplication of the point spread function was calculated when a concave aperture HIFU applicator (simulation, frequency 5 MHz, aperture diameter 12 mm, focal depth 30 mm) was used (single aperture and two apertures were used). .. As mentioned above, this kind of calculation is effective in considering the heating effect. By collecting experimental data, it is possible to formulate the relationship between sound pressure (point spread function), sound pressure of harmonics, heat reception, etc., design of applicator and radiated sound pressure (ultrasonic parameters), etc. Can be used to improve the efficiency of heat treatment. The same applies when other waves are used.

FIG. 42 is a diagram showing changes in sound pressure according to an embodiment of the present invention when a concave HIFU applicator is used. In FIG. 42, (a1) and (a2) show an image of the sound pressure by the original signal and the sound pressure of the square signal (the left includes direct current and the right only harmonics) when one aperture is used. The image of is shown. (B1) and (b2) show the sound pressure image of the original signal and the sound pressure of the multiplication signal (left is DC when the two openings are used (the intersection angle is ± 5 ° with respect to the lateral direction). , And the image on the right shows only harmonics. The image is based on envelope detection, and the image size is 3.8 × 12.8 mm ² . It can be confirmed that the sound pressure of the second harmonic component obtained by each of the square and the multiplication is concentrated in a desired region and the contrast is increased. In this way, it is possible to evaluate the intensity (Intensity, that is, electric power) of the fundamental wave and to estimate the sound pressure distribution shape of the generated harmonic (second or higher harmonic). In addition, the power consumed by harmonics (Intensity) can also be evaluated. The harmonics that are actually observed can be evaluated in the same manner.

  In the above, regarding the imaging apparatus according to the embodiment of the present invention, mainly, the non-linear operation device for electromagnetic waves, vibration including sound, heat wave, or a corresponding signal is described. Enhance effect, simulate non-linear effect, or realize virtually (that is, non-linear effect is generated except when physical, chemical, or biological non-linear effect is produced). It is also possible). In that case, the device relating to the wave used can be used simultaneously to receive the wave, or the invention can be implemented on the basis of signals received at different times if they are in phase. That is, the present invention can handle a case where a plurality of waves are simultaneously generated and a case where the waves are independently generated.

  Also, in electromagnetic waves, vibrations, or heat, if the frequency is different, the dominant behavior differs depending on each measurement object (medium), and it is appropriate to change the name (for example, regarding electromagnetic waves, Regarding vibrations such as microwaves, terahertz waves, and radiation such as X-rays, for example, when human soft tissues are targeted, shear waves do not propagate as waves due to the effect of attenuation in the mega Hz band, and ultrasonic waves are dominant. However, at low frequencies such as 100 Hz, the incompressible characteristic is strong and the shear wave is dominant.) The present invention enhances the non-linear effect between those having different behaviors, or the non-linear effect. Can be simulated or virtually realized.

  In that case, the device relating to the wave used can be used simultaneously to receive the wave, or the invention can be implemented on the basis of signals received at different times if they are in phase. Of course, phenomena such as the propagation velocity of each wave, attenuation, scattering, and reflection have dispersion characteristics, and there is a limit that it must be used appropriately in consideration of the SN ratio of the received signal. However, the application range of the present invention is extremely wide, including the capability of generating high-frequency signals and low-frequency signals that cannot be physically generated or captured.

  In addition, it is described that the nonlinear calculation and the nonlinear effect in the measurement target are imaged, or that they are applied to other measurement, and that the harmonics may be actively propagated to the measurement target. The fundamental wave may be actively used in them. It is also possible to construct an over-determined system. The fundamental wave is processed similarly to the harmonic wave.

  Further, at least one of the plurality of signals obtained through the non-linear operation is subjected to arbitrary detection processing, or a plurality of signals which may include a fundamental wave is subjected to arbitrary detection processing and then superimposed, or In some cases, an arbitrary detection process may be performed on a plurality of signals, which may include a fundamental wave, that have been superimposed as they are, and other measurements such as imaging or displacement may be performed. Regarding superposition, the former incoherent addition (incoherent compounding) is effective in reducing speckles, and the spatial resolution does not decrease when a high frequency signal is generated and used. The low spatial resolution that often occurs with ordinary speckle reduction does not pose a problem. When a low frequency signal is generated and used, it may be useful although the spatial resolution is lowered. On the other hand, the latter coherent addition (coherent compounding) can widen the band of signals, that is, can improve the spatial resolution. In particular, when a high frequency signal is generated and used, the frequency can be increased, and when a low frequency signal is generated and used, the frequency can be decreased. As a result, the imaging can have a high spatial resolution, and the displacement and other measurements can be highly accurate. As described above, signals obtained when a plurality of beams or waves are generated or obtained by frequency division of the spectrum are also included in these processing targets including the non-linear processing.

  The displacement measurement can be applied as described above, for example. The range of applications is immeasurable, such as radar, sonar, and environmental measurement. In addition to displacement, temperature may be measured, for example. In some cases, temperature sensing is performed directly using a temperature sensor, or the temperature dependence of wave propagation characteristics is detected.For example, when ultrasonic waves are used, heat that reflects changes in sound velocity and changes in volume due to temperature changes is used. The temperature distribution may be measured based on signal processing for the purpose of strain measurement. The chemical shift of the nuclear magnetic resonance frequency may be detected based on signal processing. A heat wave is observed and its nonlinearity can be imaged and it can be applied to increase the efficiency of heat treatment.

  In addition, in the case of actively observing the non-linear effect in the measurement object and in the case of positively performing the non-linear processing according to the present invention, both can be switched and used, or both can be used simultaneously. Through computation, it may be possible to elucidate non-linear effects within the measurement object. That is, by making full use of the non-linearity of the signal source, the contrast agent, and the analog or digital non-linear operation used, the non-linearity effect in the measurement target can be measured with high accuracy and imaged.

  The above-mentioned imaging and measurement are based on performing appropriate beam forming, and an appropriate detection method and tissue displacement measuring method are also important. In the past, the inventor of the present application has particularly used a lateral modulation method using a crossed beam as a beam forming method such as square detection in addition to quadrature detection and envelope detection as a detection method for a multidimensional signal (Non-Patent Document 13 and 29), spectral frequency division method (see Non-Patent Document 29), adjustment of wave or beam shape by filtering of spectrum, method of using many crossed beams, and over-determined system method. In addition, as a displacement vector measuring method, a multidimensional autocorrelation method, a multidimensional Doppler method, a multidimensional cross spectrum phase gradient method, a phase matching method, etc. have been developed (see Non-Patent Documents 13 and 29). In addition, the (viscous) shear elastic modulus distribution and thermophysical property distribution can be reconstructed and imaged based on displacement and strain measurements. Not only the original wave or signal, but also the wave or beam generated by superposition of multiple waves or signals, or non-linear effects (sometimes including pseudo), a pseudo wave in spectral frequency division Or a beam can be generated, and the wave or beam shape can be adjusted in spectral filtering.

  A signal obtained by superimposing a plurality of signals that may include a fundamental wave, or a signal that is obtained by spectrally dividing or filtering at least one of the plurality of signals that may include a fundamental wave in the frequency domain ( Non-Patent Document 29), or an original signal that has not been subjected to these processes, or a combination of these signals to form an over-determined system, and image processing is performed by the above process. Or, other measurement such as displacement may be performed.

  As described above, according to the present invention, a non-linear reaction or wave for high intensity during wave propagation is superposed on a coherent signal obtained by detecting a transmitted wave, a reflected wave, or a scattered wave of an arbitrary wave by a sensor. Imaging using the original signal by obtaining non-linear effects (generation of harmonics, chords, difference sounds, etc.) such as multiplication and exponentiation when performing analog calculation or digital calculation using a computer. In comparison with, it realizes high-frequency and wide-band, high-contrast, and high spatial resolution imaging. It is also possible to perform low-frequency imaging instead of high-frequency imaging. Further, under the same effect, as compared with the Doppler measurement using the original signal, the displacement, velocity, acceleration, strain, or distortion rate can be measured with higher spatial resolution and higher accuracy.

  The superposition of waves means what is physically realized during beamforming, between beamformed waves, unbeamformed waves, and the like. When the intensity of the wave is weak, the principle of superposition that is established by the linear law is mainly observed, but when the intensity of the wave is strong, signals other than superposition that are affected by nonlinear effects such as multiplication and exponentiation (that is, harmonics). (Waves, chords, difference tones) are observed, and the present invention focuses on this latter phenomenon. The present invention is also characterized in that it can be used for all of these wave components and superposed waves without depending on their intensities. Of course, it also applies to the fundamental wave and a wave containing a harmonic component artificially radiated or generated during propagation. Examples of harmonics generated during propagation include ultrasonic harmonic signals and the like.

  On the other hand, according to the present invention, for example, a beam generated by beamforming (physical one including apodization, delay processing, or addition processing, or calculation) or a wave which is not subjected to beamforming is used. With regard to arbitrary waves such as itself (including received signals for plane waves and aperture plane synthesis), transmitted waves, reflected waves, or scattered waves, multiple non-linear effects due to high intensity and a plurality of waves propagating in the same or different directions Highly accurate measurement of non-linear effects such as multiplication and exponentiation caused by overlapping waves (waves of the same physical quantity but different directions, waves of the same physical quantity with different parameters, waves of different types of physical quantities), etc. Or, in order to simulate, for example, after the signal is detected by the transducer, those signals are positively calculated by using the analog calculator or the digital calculator, and the broadband harmonics, chords, and difference You can get the sound. It is also possible to emphasize a physical, chemical, or biological non-linear effect, and to produce a non-linear effect when the non-linear effect cannot be observed or does not occur. It is possible. Moreover, a plurality of detection signals can be obtained at the same time. In addition, the application of a basebanded signal generated by receiving a physical action is also included in the present invention (such as removing harmonics obtained by a pulse inversion method or a filtering method from a received signal, or performing the above calculation). Or applying the signal estimated by calculation).

  The inventor of the present application has previously disclosed a lateral modulation method using a crossing wave (plane wave or the like) or a crossing beam based on a linear law (having carrier frequencies in the depth direction and the lateral direction). According to the invention, it is possible to obtain the effect of exponentiation even in this lateral modulation, and it is also possible to obtain the effect of multiplication between crossed waves. Further, normally, the power effect and the product effect can be obtained by increasing the wave intensity, but according to the present invention, those nonlinear effects can be obtained regardless of the intensity.

  Further, according to the present invention, a basebanded signal can be obtained by a new detection process that can be easily implemented with a small amount of calculation instead of ordinary quadrature detection or envelope detection, and its effect can be obtained in echo imaging and Doppler measurement. Is obtained. However, the detected signal includes direct current, which is different from the normal baseband signal, and therefore it is used as it is or after the direct current is removed by analog processing or digital processing. Besides, the application of the base banded signal obtained by receiving the physical action is also included in the present invention. A signal in the baseband band generated by calculation is also called a basebanded signal.

  For example, in the fields of medical ultrasonic waves and sonar, nonlinear phenomena in the propagation process of ultrasonic waves in a living body (when the sound pressure is high, the bulk elastic modulus acts high, the sound velocity is fast, the waveform is distorted, and the accumulation occurs in the propagation process. However, the application of a physically generated basebanded signal is not disclosed. Application of a basebanded signal physically generated by other non-linear phenomena is also not disclosed. It should be noted that baseband signals, baseband signals, and incoherent signals such as envelope detection or square-law detection are also included in the processing target of the present invention.

  In particular, with regard to Doppler measurement, the present inventor uses a multidimensional signal, which is different from normal Doppler measurement in which displacement in the propagation direction of a wave is measured, and displacement vector, velocity vector, acceleration vector, strain It is possible to measure tensor or distortion tensor with high accuracy. According to the present invention, unlike normal detection, a signal (base banded signal) detected in any one direction from a multidimensional signal can be obtained at the same time. It is also possible to easily perform those measurements in a short time with a calculation amount. Even in this case, echo imaging using the harmonics obtained at the same time and the above-mentioned base banded signal is possible. In addition, it is possible to suppress side lobes and increase the contrast. The temperature is measured as described above.

  Basically, multiplication of sine and cosine signals of different single frequencies produces chords and difference tones, and when power calculation is performed, the frequency of the signal becomes twice as high as the power factor. It is possible to not only increase the frequency but also widen the band for signals (distorted waves) having a plurality of frequency components. In addition to this, an effect of suppressing so-called side lobes is obtained, and the contrast is increased. These effects are often observed as effects during propagation of particularly strong waves, but in the present invention, an analog or digital arithmetic process is applied to an arbitrary signal to enhance the nonlinear effect regardless of the strength. Or simulated or newly generated. It can also be realized virtually. Not only in the case of having the spatial resolution, but also in the continuous wave, similarly, the harmonic or the detection signal can be physically or artificially obtained. Understanding the physically generated basebanded signal under the present invention makes its application engineering useful. For example, it may be possible to measure a displacement or a displacement vector component (a normal one-dimensional displacement measuring method can be used). In addition, it is possible to measure displacements and displacement vector components using observed harmonics (the above-mentioned various multidimensional displacement vector measurement methods can be used), and to configure an over-determined system. It can also be applied to imaging (high SN ratio, high resolution, speckle reduction, etc.), displacement component measurement (high accuracy), and the like, as in the case of using the nonlinear processing of the present invention. In these cases, it is also effective to positively apply the contrast agent to enhance the non-linear effect.

  In addition, the present invention provides heating, heating, cooling, freezing, welding, repairing, heating of cancer lesions and the like in any object, which is performed by using waves (laser, ultrasonic waves, focused intense ultrasonic waves, etc.). , Cryotherapy, or cleaning of arbitrary objects (glasses, etc.), enhancing their effects through non-linear phenomena, increasing resolution, and predicting their effects (for example, using strong ultrasound The power effect during heating and the high spatial resolution due to addition when enhancing the effect using crossed beams, as well as high frequency and high spatial resolution as the effect of multiplication) It becomes possible. Even in these cases, the continuous wave may be used, and the same effect can be obtained.

  The present invention can also obtain a non-linear effect under physical conditions in which no non-linear effect is physically obtained (for example, when the intensity cannot be increased with respect to the measurement target or when high intensity cannot be obtained due to high frequency). Effectively, but conversely, the invention is carried out under conditions in which, for example, ultrasound echo imaging, displacement measurement, temperature measurement, or contrast agents such as microbubbles are used during treatment to enhance the nonlinear effect. It is also effective. That is, the present invention can enhance the non-linear effect, but can also be simulated, newly generated, or virtually realized. Further, the present invention can be carried out in imaging, displacement measurement, treatment, etc. for the purpose of purely achieving high resolution, high accuracy, and high efficiency.

  According to the present invention, similarly to the harmonic imaging, it is possible to increase the frequency and bandwidth, increase the contrast, or suppress side lobes, and it is possible to perform nonlinear imaging with a high SN ratio. Besides, analog detection or digital detection can be performed at the same time without requiring a large amount of memory or calculation.

  The effectiveness of the present invention has been verified by performing ultrasonic echo imaging and measurement imaging through simulations and agar phantom experiments. INDUSTRIAL APPLICABILITY The present invention is applicable to arbitrary coherent signals other than the ultrasonic echo method (light waves, OCT, electricity, magnetic field signals, radiation such as X-rays, and heat waves in familiar objects) and different types of coherent signals. Can also be applied. Signals including those that have been made incoherent by analog processing (for example, energy detection of a received signal using a sensor or energy detection using a non-linear element) or digital processing may be processed together with the coherent signal.

  On the other hand, in the field of image measurement, it is often observed that a coherent signal is converted into an incoherent signal (result display is an image) through various kinds of detection (physical phenomenon or normal signal processing). Known (various such as cross-correlation processing and optical flow). If this method is used for an incoherent signal, a wide band (higher resolution) can be obtained. The high resolution detection signal obtained by the present invention can also be used. The measurement accuracy of those movements is also improved. That is, the invention applies to any coherent or incoherent signal.

  Imaging and motion measurement using the above coherent signals and incoherent signals have been carried out in various fields including the above examples and have a very long history. Alternatively, it is effective and useful to perform wideband high-resolution and high-contrast imaging including low frequencies and to measure displacement and the like with high accuracy. It is effective, including the fact that it has the engineering effect of multidimensional signal processing. Further, in the above other applications such as treatment, it is also effective and useful to evaluate and apply the effect based on imaging of the non-linear effect.

  In an imaging device, it is useful to perform multiplication or calculation to generate a harmonic component and a basebanded signal (the above new detection signal) and generate an image signal based on them, but multiplication and calculation The same effect can be obtained not only when the high-order nonlinear processing is performed. Depending on cost and the like, it may be selectively adopted or used in combination with the conventional technique.

  The present invention is not limited to the above embodiments, and many modifications can be made within the technical idea of the present invention by a person having ordinary skill in the art.

  INDUSTRIAL APPLICABILITY The present invention can be used in a beamforming method for performing beamforming using arbitrary waves coming from a measurement target, and a measurement imaging device and a communication device using such a beamforming method. is there.

  Radar, sonar, and other wave signals such as optical system waves, sound waves, and heat waves are often already generated by digital devices at present, and it is also high-level for the purpose of applying the signals. It can be applied in conjunction with signal generation only with the processing ability to perform the next calculation. Various devices have been made multidimensional, and the importance of the present invention is increased. The objects to be measured are solids, fluids, rheology, inorganic substances, organic substances, living things, the environment, etc. are immeasurable, and the measurement range is expected to expand. In the future, the miniaturization of each device in the equipment will continue to progress, and the computational stress will be much higher, so it will be possible to incorporate a computer at a lower cost, and many convenient and real-time equipment will be realized. You can expect to go. Further, it is considered that not only a mere wave imaging device but also development of applications through measurement using waves becomes more active, and the range of applications is broadened. It is expected that the digitization of various devices will further progress in the future, and in that case, the demand for high-precision and high-speed beamforming capable of generating a high-precision signal according to the present invention in real time will increase. After all, in addition to the fast processing, there is no need to perform the interpolation approximation that has been required up to now. However, in the present invention, further high speed is emphasized, and if necessary, processing involving interpolation approximation may be performed, although accuracy is reduced. It is also an effective device for ordinary communication and sensor networks. The applicability and marketability of the digital beamforming according to the present invention based on digital signal processing are far higher.

  10 ... Transmitting transducer (or applicator), 10a ... Transmitting aperture element, 20 ... Receiving transducer (or receiving sensor), 20a ... Receiving aperture element, 30 ... Device body, 31 ... Transmitting unit, 31a ... Transmitter, 32 ... Receiving Unit, 32a ... Receiver, 32b ... AD converter, 32c ... Memory (or storage device or storage medium), 33 ... Digital signal processing unit, 34 ... Control unit, 35 ... Reception unit (or reception device), 35a ... Reception 35b ... AD converter, 35c ... Memory (or storage device or storage medium), 35d ... Phasing adder, 35e ... Other data generating section, 40 ... Input device, 50 ... Output device, 60 ... External storage device, 1 ... Object to be measured, 1a ... Contrast agent, 110 ... Transducer, 111 ... Non-linear device, 112 ... Working device, 120, 120a, 120b ... Imaging device main body, 121 ... Transmitter, 121a ... Transmission delay element, 122 ... Receiver, 122a ... Reception delay element, 123 ... Filter / gain adjustment section, 124 ... Non-linear element, 125 ... Filter / gain adjustment section, 126 ... Detector, 127 ... AD converter, 128 ... Storage device, 129 ... Reception beamformer, 130 Computation unit 131 Image signal generation unit 132 Measurement unit 133 Control unit 134 Display device 135 Analog display device 140 External storage device

Claims (73)

In an orthogonal coordinate system defined by a receiving aperture element array, a beam used in a measurement imaging apparatus that generates an image signal of the measurement target when an arbitrary wave is transmitted from a wave source located in an arbitrary direction toward the measurement target. A forming method,
(A) receiving a wave coming from the measurement target by at least one receiving aperture element and generating a received signal;
By performing at least Fourier transform and wave number matching on the reception signal generated in step (a), a zero-degree or non-zero degree deviation angle or elevation angle or azimuth angle with respect to the front direction of the reception aperture element. There line beamforming processing of the transmission component or reception component includes performing a transmission content or receive content steering makes the steering angle that is desired to be the first direction and the second direction or the third coordinate axis direction (B) generating an image signal in the Cartesian coordinate system of
Equipped with,
Step (b), in order to perform wave number matching without performing a direct interpolation approximation process on the angular spectrum in the wavenumber domain or the frequency domain obtained by performing multi-dimensional Fourier transform on the received signal, ( b1) When the declination of the steering angle or the elevation angle is zero degrees, the received signal is subjected to Fourier transform in the first direction, and is subjected to Fourier transform in the second direction or the third direction. And then shifting the angular spectrum in wavenumber space or frequency space by multiplying by a complex exponential function having an exponential part comprising spatial coordinates in the first direction and the wavenumber or carrier frequency of the wave , (B2) When the declination of the steering angle or the elevation angle is non-zero, the received signal is subjected to Fourier transform in the first direction, and then in the second direction or the third direction. After multiplying by a complex exponential function having an exponential part including spatial coordinates and the wave number or carrier frequency of the wave, and performing Fourier transform in the second direction or the third direction, the spatial coordinates in the first direction are obtained. A beamforming method comprising shifting the angular spectrum in wavenumber space or frequency space by multiplying by a complex exponential function having an exponential part including the wavenumber of the wave or the carrier frequency . Step (b) is
And facilities Fourier transform with respect to (i) before Symbol received signal, and to perform wave number matching is subjected directly interpolation approximation at least one orthogonal axis,
(Ii) performing phasing addition on the received signal,
2. The beamforming method according to claim 1, comprising directly generating an image signal different from the image signal in a desired rectangular coordinate system based on at least one of the above . In a Cartesian coordinate system defined by the receiving aperture element array, when an arbitrary wave is transmitted from a wave source located in an arbitrary direction toward a measurement target, a measurement imaging device that generates an image signal of the measurement target,
At least one receiving aperture element that receives a wave coming from the measurement target and generates a received signal;
By performing at least Fourier transform and wave number matching with respect to the reception signal generated by the reception aperture element, a zero-degree or non-zero degree deviation angle, an elevation angle, or an azimuth angle is expressed with respect to the front direction of the reception aperture element. There line beamforming processing of the transmission component or reception component includes performing a transmission content or receive content steering makes the steering angle that is desired to be the first direction and the second direction or the third coordinate axis direction A signal processing unit that generates an image signal in the Cartesian coordinate system of
Equipped with,
To the signal processing unit performs a wavenumber matching without applying direct interpolation approximation process on the angular spectrum in the wavenumber domain or the frequency domain obtained by performing multi-dimensional Fourier transform on the received signal, the When the declination or the elevation angle of the steering angle is zero degrees, the received signal is subjected to Fourier transform in the first direction, and after subjected to Fourier transform in the second direction or the third direction, The angular spectrum is shifted in a wave number space or a frequency space by multiplying by a complex exponential function having an exponential part including the spatial coordinate in the first direction and the wave number or carrier frequency of the wave , and the steering angle declination angle is shifted. Alternatively, when the elevation angle is non-zero, after the Fourier transform is performed on the received signal in the first direction, the spatial coordinates in the second direction or the third direction and the wave number or carrier frequency of the wave. After multiplying by a complex exponential function having an exponential part including and performing Fourier transform in the second direction or the third direction, the spatial coordinates in the first direction and the wave number or carrier frequency of the wave are included. A metrology imaging device that shifts the angular spectrum in wavenumber space or frequency space by multiplying by a complex exponential function having an exponential part . The signal processing unit,
And facilities Fourier transform with respect to (i) before Symbol received signal, and to perform wave number matching is subjected directly interpolation approximation at least one orthogonal axis,
(Ii) performing phasing addition on the received signal,
The measurement imaging apparatus according to claim 3, wherein an image signal different from the image signal is directly generated in a desired rectangular coordinate system based on at least one of the above .   The signal processing unit performs beamforming processing for transmission or reception by at least one of beamforming processing without focus and dynamic focusing based on monostatic or multistatic aperture plane synthesis processing. Item 5. The measurement imaging device according to Item 3 or 4.   The measurement imaging apparatus according to claim 3, wherein the reception aperture element or the signal processing unit performs apodization processing for transmission or reception by using linearity of apodization processing.   When the signal processing unit performs phasing addition on the received signal, it determines the apodization of the transmission or reception based on an adaptive beamforming method including a minimum variance beamforming and a Capon method. , When regularizing the covariance matrix used therein, the regularization parameter for adjusting the degree of regularization is spatially variant based on the SN ratio of the signal at each position, or 7. The metrology imaging device according to claim 4, wherein a positive definite operator including a gradient operator or a Laplacian is used as the regularization operator instead of the unit matrix.   The signal processing unit, for the same received signal generated by the receiving aperture element, performs a plurality of times of beam forming processing for transmission or reception with different wave parameters or beam forming parameters or beam forming itself, The metrology imaging apparatus according to claim 3, wherein the results are superimposed in the spatial domain, the wavelength domain, or the frequency domain to generate a new wave parameter, beamforming parameter, or beamforming itself.   The signal processing unit divides the multi-dimensional spectrum of the received signal in the wave number domain or frequency domain before performing the wave number mapping after the Fourier transform, or in the wave number domain before performing the inverse Fourier transform after the wave number mapping. Alternatively, the measurement imaging according to any one of claims 3 to 8, which is divided in a frequency domain and has a new wave parameter or a beam forming parameter, or generates a plurality of pseudo beam with a new beam forming. apparatus.   The measurement imaging apparatus according to claim 3, wherein the signal processing unit processes only a spectrum of a band selected in a wave number domain or a frequency domain.   The at least one transmission aperture element for transmitting at least one beam or wave forming a steering angle represented by a zero degree or non-zero degree declination angle or elevation angle and azimuth angle toward the measurement target, further comprising at least one transmission aperture element. Item 10. The measurement imaging device according to any one of items 10.   At the same time or at different times of the same time phase, or at substantially the same time phase, the declination angle or elevation angle and azimuth angle are the same toward the measurement target, or at least one of them is different. And further comprising at least one transmit aperture element transmitting a plurality of beams or waves in which all other wave parameters and beamforming parameters are the same or at least one of which is different. Item 11. The measurement imaging device according to any one of items 1 to 11.   The beam or wave transmitted from the at least one transmitting aperture element is one of a focused or unfocused plane wave, circular wave, cylindrical wave, spherical wave, and any curved wave. The measurement imaging apparatus according to claim 11 or 12. If multiple waves are received at the same or different times of the same time phase, or at substantially the same time phase, they are superposed or superposed in the spatial domain before performing the Fourier transform. Or before being subjected to wavenumber mapping after Fourier transform, superposed in the wavenumber domain or frequency domain, or superposed, or before performing inverse Fourier transform after wavenumber mapping, respectively. The measurement imaging apparatus according to any one of claims 3 to 13, wherein the multidimensional spectrums of the waves are overlapped in the wave number domain or the frequency domain, or are overlapped after the inverse Fourier transform .   The measurement imaging apparatus according to claim 14, wherein the plurality of waves are at least one or two of an arbitrary electromagnetic wave, an arbitrary mechanical wave, and an arbitrary heat wave.   The measurement imaging apparatus according to any one of claims 3 to 15, wherein the received wave is a wave of a type physically different from the wave transmitted toward the measurement target. Dynamic of the transmitted or received component in a two-dimensional or three-dimensional Cartesian coordinate system using the coordinate in the axial direction y defined by the array of mechanically scanned or electronically scanned effective aperture elements and the transverse direction x or z orthogonal thereto. A measurement imaging apparatus for performing multi-static aperture plane synthesis for generating a focused beam, wherein a deflection angle of zero degree or non-zero degree formed by the beam direction and the axial direction of the generated transmitted or received beam is polarized. When expressed in angle or elevation and azimuth,
The at least one transmit aperture element has any x-coordinate or so that the incoming wave is generated by at least transmission, forward scatter, refraction, reflection, backscatter, or diffraction at the measurement object. A plurality of transmitting aperture elements having x and z coordinates and further having a y coordinate of zero, which doubles as any of the receiving aperture elements in the receiving effective aperture element array or which is different from any of the receiving aperture elements. At least one of the following, or has an arbitrary x coordinate or x and z coordinates, and further has a non-zero constant y coordinate, at a position facing the reception effective aperture element array. At least one of a plurality of transmit aperture elements in the transmit effective aperture element array,
Wherein the at least one receiving opening elements, a plurality of reception for generating the received signal received at one of the same or different transmission aperture element waves of different positions the wave arrives from the measurement target for each transmitted from the at no less It is one of the aperture element,
The signal processing unit performs at least Fourier transform and wave number matching or phasing addition on the reception signals generated by the plurality of reception aperture elements, and thus has a multi-static type having a deflection angle for transmission or reception. In order to perform the aperture plane synthesis processing of (1), the transmission aperture is set for each of the reception signal groups obtained by arranging the reception signals in which the relative position Δx or the relative positions Δx and Δz in the lateral coordinate between the transmission position and the reception position are equal. When the y-coordinate of the element is zero, the transmitting aperture element represented by the y-coordinate of the interest point including the position of the transmission or reception aperture and the relative position Δx or the relative positions Δx and Δz, the interest point, and the reception point When the distance is half the linear distance connecting the aperture element or the y coordinate of the transmitting aperture element is non-zero, the y coordinate of the point of interest and the y coordinate of the transmitting aperture element and the relative position Δx or relative position Δx. And a distance between the point of interest and the receiving aperture element, which is represented by using Δz and Δz, in monostatic aperture plane synthesis performed based on the beamforming processing of the transmission component or the reception component. The measurement imaging apparatus according to claim 11, wherein each of the image signals obtained by setting the deflection angle is corrected with respect to the position in the lateral direction, and they are superimposed to generate an image signal.   The signal processing unit sets the estimated value of the y-coordinate of the unknown wave source to the same value as the y-coordinate of the effective transmission aperture element in order to generate an image signal representing the unknown wave source or the propagation of the wave generated by the unknown wave source. The measurement imaging apparatus according to claim 11, wherein the beam forming is performed by performing the beam forming. In a two-dimensional or three-dimensional Cartesian coordinate system using the coordinate in the axial direction y determined by the array of receiving aperture elements and the coordinate in the transverse direction x or z orthogonal thereto, at least one generated by at least one arbitrary wave source. In the case where a deflection angle of zero degree or non-zero degree formed by a propagation direction and an axial direction of any wave or at least one arbitrary beam or wave to be transmitted is represented by an argument or an elevation angle and an azimuth angle,
The at least one receiving aperture element constitutes a plurality of receiving effective aperture arrays consisting of a plurality of receiving aperture elements at different positions set in the physical aperture, and at least one beam or wave arriving from the object to be measured. To generate a received signal,
The signal processing unit performs at least Fourier transform and wave number matching or phasing addition on the reception signals generated by the plurality of reception effective aperture element arrays, and thereby the transmission component having the steering angle of transmission and reception and In the beamforming processing of the transmission portion or the reception portion including the steering of the reception portion, the transmission wave is processed as a wave without focus to perform the dynamic focusing processing of the reception, or the aperture surface of the transmission portion or the reception portion is received. While performing the combining process, with respect to the received signal,
(I) reception of received signals by overlapping received signals generated by receiving aperture elements at the same position of the plurality of receiving effective aperture element arrays or by overlapping beams or waves. Obtaining one received signal group consisting of superposition of received signals generated by the aperture element, and performing the image signal generating process once by the beam forming process;
(Ii) The beamforming process is performed on each of the reception signals generated by the plurality of reception effective aperture element arrays each time a beam or a wave is transmitted from at least one identical or different transmission aperture element . Generate low resolution image signals and overlay them,
(Iii) An image signal obtained by the beamforming process as an echo group having an equal relative distance between the effective transmission aperture element array or each transmission aperture element in the effective transmission aperture element array and each reception aperture element in the reception effective aperture element array. And superimpose them,
The measurement imaging apparatus according to any one of claims 3 to 18, which generates an image signal based on any one of the above.   The signal processing unit performs a coherent addition (coherent compounding) on a wave parameter, a steering angle, other beam forming parameters, or a plurality of wave signals different in beam forming, thereby generating a new wave parameter or an axial direction or A method for generating a non-overlapping spectrum in a frequency domain or a wave number domain when a wave having a wide band in the lateral direction or another new beamforming parameter or generating a new beamformed wave is generated. The measurement imaging device according to any one of 3 to 19.   21. The measurement imaging apparatus according to claim 3, wherein the signal processing unit performs spatial alignment when superimposing a plurality of wave signals having different steering angles. The measurement imaging apparatus according to any one of claims 3 to 21, wherein the signal processing unit performs phase aberration correction on a received signal in order to correct an error that occurs in a propagation time of a wave that is transmitted or received.   The measurement imaging apparatus according to any one of claims 3 to 22, wherein the signal processing unit directly generates an image signal in a rectangular coordinate system based on a migration method.   The measurement imaging apparatus according to any one of claims 3 to 22, wherein the signal processing unit calculates an arbitrary beam or wave using a Green's function that is a general solution of a wave equation.   A two-dimensional Cartesian Cartesian coordinate system (x, y) or a three-dimensional Cartesian Cartesian coordinate system (x, y, z) using the coordinates of the axial direction y defined by the receiving aperture element array and the lateral direction x or z orthogonal thereto, or , A two-dimensional polar coordinate system (x, y) or a spherical coordinate system (x, y) using coordinates of a radial direction y and a deflection angle x or a radial direction y and an elevation angle x and an azimuth angle z determined by a receiving aperture element array having a circular shape. , Z), or a two-dimensional orthogonal curve coordinate system (x, y) or a three-dimensional orthogonal curve using coordinates of an axial direction y defined by a receiving aperture element array having another shape and a lateral direction x or z orthogonal thereto. The signal processing unit performs beamforming processing at least once using the coordinate axes of the coordinate system when at least one wave is received in the coordinate system (x, y, z). 25. The measurement imaging apparatus according to any one of items 24 to 24.   Two-dimensional Cartesian Cartesian coordinate system (x, y) or three-dimensional Cartesian Cartesian coordinate system (x, y, z) determined by the receiving aperture element array, or two-dimensional polar coordinate system (x , Y) or a spherical coordinate system (x, y, z), or a two-dimensional orthogonal curved coordinate system (x, y) or a three-dimensional orthogonal curved coordinate system (x, y) defined by a receiving aperture element array having another shape. , Z), when the reception of at least one wave is performed, the signal processing unit causes the at least one wave to be focused or focused in the beamforming processing of the transmission or reception. The measurement imaging apparatus according to any one of claims 3 to 25, which processes as one of a plane wave, a circular wave, a cylindrical wave, a spherical wave, and an arbitrary curved surface wave. The signal processing unit directly generates an image signal in the same Cartesian coordinate system as the Cartesian coordinate system, which is a Cartesian Cartesian coordinate system or a Cartesian curvilinear coordinate system in which waves are received, or a Jacobi operation Accordingly, to produce a direct image signals in different orthogonal coordinate system with no orthogonal coordinate system receiving wave is Cartesian rectangular coordinate system or orthogonal curvilinear coordinate system Ru done by performing the interpolation approximation process, according to claim 3 27. The measurement imaging apparatus according to any one of items 26 to 26.   When a wave is generated by an arbitrary wave source in a rectangular coordinate system in which transmission beamforming is different from a rectangular coordinate system in which reception beamforming is performed, the signal processing unit includes (i) a beam after reception. Prior to the forming process, the received signal is converted into a signal in a rectangular coordinate system where reception beam forming is performed by using a signal processing or a transmission or reception delay device, or (ii) the wave source transmits 28. The measurement imaging apparatus according to any one of claims 3 to 27, wherein transmission beamforming is performed so as to also serve as conversion using the delay device of. The signal processing unit, a physical wave sources, physical transmission aperture array, or virtual wave source is a physical transmit aperture element array is set separately, virtual transmission aperture array, Alternatively, the measurement imaging apparatus according to any one of claims 3 to 28, which processes the reception signal with respect to a virtual reception aperture element or a reception aperture element array.   The signal processing unit, for the same reception signal generated by the reception aperture element, a virtual wave source, a virtual transmission aperture element array, or a virtual reception aperture element or a reception aperture element array. At the time of use, a beam forming process for transmission or reception is performed in which at least one of virtual parameters including their position, orientation, size, shape, or distribution, beam forming parameters, and beam forming itself is different. Performed multiple times to have new wave or beamforming parameters, or to generate new beamformed waves, or to superimpose the results in the spatial, wavelength or frequency domain The metrology imaging apparatus according to any one of claims 3 to 29, which additionally generates a new wave parameter, beamforming parameter, or beamforming itself. The signal processing unit generates an image signal in an arbitrary range having an arbitrary coordinate in the axial direction or an arbitrary interval and an arbitrary range having an arbitrary coordinate in the lateral direction or an arbitrary interval. The measurement imaging device according to any one of 30. 32. The signal processing unit performs oversampling or upsampling in space-time before, during, or after beamforming, or widens a band through zero padding of a spectrum in a frequency domain. The measurement imaging apparatus according to any one of items.   33. The signal processing unit oversamples or upsamples the received signal in order to reduce the deterioration or artifact of the generated image signal due to the interpolation approximation process. The described measurement imaging device. Wherein the at least one transmission aperture element or the at least one receiving aperture element is one of a plurality of aperture element for transmitting or receiving waves, measuring imaging according to any one of claims 3-33 apparatus.   The measurement imaging apparatus according to any one of claims 3 to 34, wherein the signal processing unit performs parallel processing to reduce calculation time.   The said signal processing part implements the fast Fourier transform which directly produces | generates the result of the wave number matching obtained by multiplying the Fourier transform regarding the time of the said received signal by a complex exponential function. The measurement imaging device according to [1]. The signal processing unit includes (i) a wave including a longitudinal wave, a transverse wave, or a surface wave to be observed, (ii) a wave source to be observed, (iii) a medium to be observed, and (iv) an object to be observed. Measuring or analyzing at least one of the waves transmitted or received for sensing in more detail, or the wave itself transmitted or received for sensing in order to have a new characteristic, or The result directly measured for the observation target from the wave transmitted or received for sensing, or the result measured directly for the observation target from the wave itself or the wave transmitted or received for sensing The measurement imaging device according to any one of claims 3 to 36, which uses a result processed or processed in a spatial domain, a wavenumber domain, or a frequency domain for measurement or imaging. The signal processing unit, based on the reversibility of the Fourier transform and the inverse Fourier transform, returns the generated image signal to the reception signal before the beam forming for the transmission or the reception, and performs another beam forming. The measurement imaging device according to any one of 3 to 37 . The measurement imaging device according to any one of claims 3 to 38 , wherein the signal processing unit performs compressed sensing. The signal processing unit, instead of performing the beam forming process on the received signal, the performing beamforming processing on the image signal after generating the image signal, to any one of claims 3-39 The described measurement imaging device. In the case where the coordinate system in which the physical transmission beamforming is physically performed is a Cartesian coordinate system or a Cartesian coordinate system which is a Cartesian curve coordinate system, the signal processing unit determines the Cartesian Cartesian coordinate system or Cartesian curve coordinate determined by the receiving aperture element array. It generates an image signal in physically orthogonal coordinate system is performed with transmit beamforming instead of the orthogonal coordinate system is a system, measuring imaging apparatus according to any one of claims 3-40. The signal processing unit, as the information about the wave source position or the transmission aperture element, the position with respect to the reception aperture element, the direction or distance of the existing position, the direction of the aperture, or information about the time or propagation direction of the generated wave. The measurement imaging apparatus according to any one of claims 3 to 41 , which, when provided, performs beamforming according to the information. The signal processing unit, for the received signal or the image signal generated by beamforming, determines the centroid frequency or the instantaneous frequency of the multidimensional spectrum, from which the direction of the wave source or the propagation direction of the wave is determined. determined, performs beamforming by adjusting the deflection angle of transmission or reception, measuring imaging apparatus according to any one of claims 3-42. The signal processing unit performs a process of obtaining a direction in which a wave source exists or a propagation direction of a wave for a plurality of reception apertures or reception effective apertures, and geometrically obtains a position or direction in which the wave source exists. The measurement imaging device according to any one of 3 to 43 . When the received signal includes a plurality of received signals of waves generated from a plurality of different wave sources, the signal processing unit performs beamforming having a deflection angle of a propagation direction of the waves to be observed. The measurement imaging device according to any one of 3 to 44 . When the received signal includes a plurality of received signals of waves generated from a plurality of different wave sources or a plurality of received signals of interfering waves , the signal processing unit causes the multi-dimensional spectrum analysis , MIMO (Multiple-input). and Multiple-output), SIMO (Single-input and Multiple-output), MUSIC (Multiple Signal Classification), blind separation, independent component analysis, principal component analysis, code, matched filter, or various parametric methods. whether to separate by beam forming process the plurality of received signals, or to separate a plurality of image signals obtained by the beam forming process for the plurality of received signals, according to any one of claims 3-45 Measurement imaging device. The signal processing unit regularizes a matrix to which an inverse is applied in the signal processing, and sets a regularization parameter that adjusts the degree of regularization as a spatial variant based on the SN ratio of the signal at each position. 47. The metrology imaging device of claim 46 , or using a positive definite operator comprising a gradient operator or Laplacian instead of an identity matrix as the regularization operator. The plurality of different wave sources include a reflector that produces a specular reflection signal and a scatterer that produces a scatter signal;
In order to separate the specular reflection signal and the scattered signal, the signal processing unit processes two or more input data including the specular reflected signal as a common signal and the independent scattered signal or noise mixed as a mixed signal. The measurement imaging device according to claim 46 or 47 . The signal processing unit directly calculates an image signal in a Cartesian coordinate system that is a Cartesian Cartesian coordinate system or a Cartesian curve coordinate system in which an image signal is generated by the beam forming process, or through an interpolation process or a Jacobi calculation. the performing an operation on the image signal represented by using different orthogonal coordinate system and the orthogonal coordinate system is a Cartesian rectangular coordinate system or orthogonal curvilinear coordinate system the image signal is generated, the wave motion of the observation target propagation displacement The measurement imaging apparatus according to any one of claims 3 to 48 , which calculates at least one of: a velocity, an acceleration, a strain, a strain velocity, a temperature, and a characteristic. The signal processing unit uses at least one of ultrasonic waves or optical ultrasonic waves that are mechanical waves, and MRI waves that are electromagnetic waves, OCT waves, laser light, microwaves, terahertz waves, or X-rays. The measurement imaging apparatus according to any one of claims 3 to 49 , which performs Doppler observation. The signal processing unit performs measurement using microwave or terahertz wave or infrared, based on radiation, performs observing internal imaging of temperature distribution measurement according to any one of claims 3-50 Imaging equipment. 52. The signal processing unit according to claim 3, wherein the observed wave is a target, and the observed wave or the dynamic state or state of the medium is observed based on Doppler processing or image processing. Measurement imaging device. The signal processing unit is a wave or spectrum generated by superimposing a plurality of different physically generated waves or a plurality of different waves on the equation relating to the displacement vector component of each position of interest or the displacement component of the wave propagation direction. When more than the number of unknown displacement components is obtained from the wave generated by the frequency division of, the reciprocal of the variation of the displacement observed or the reciprocal of ZZLB (Ziv-Zakai Lower Bound) is used as the weight of the equation (i). The measurement imaging apparatus according to any one of claims 3 to 52 , which is solved by the method of least squares or regularization, or (ii) is used as a weight value when obtaining a weighted average of a plurality of observation results. When observing the displacement vector, the signal processing unit performs digital demodulation processing on the received signals of a plurality of intersecting waves, and in the direction in which aliasing occurs, digital demodulation is performed without widening the processing of the received signals. The measurement imaging apparatus according to any one of claims 3 to 53 , which performs Doppler processing based on a carrier frequency of each previous reception signal in the direction. In order to observe the wave source behind the obstacle or the shield from the front side of the obstacle or the shield, a diffracted wave is reflected by using at least two mirrors and a crossing wave is transmitted in front of the obstacle or the shield. passively receiving Te to or, in order to observe the measurement target of the rear of the obstacle or person or found the obstacle or shield prior to shield the wave that intersects with at least two mirrors Actively transmitting to the measurement target from the front, receiving transmission, forward scattering, refraction, reflection, or backscattering waves in the measurement target, and the signal processing unit performs axial or lateral direction by demodulation processing. Generating at least two waves having a carrier frequency of, and performing imaging through the obstacle or the shield, or measuring and imaging displacement of the wave source or the measurement target in an arbitrary direction. 54. The measurement imaging device according to any one of 54 . In the case of observing the isotropic or non-isotropic physical properties or its determines the propagation velocity of the wave to be observed, the signal processing unit,
(I) propagating a wave to be observed in at least one desired direction and transmitting or receiving a wave for sensing to perform Doppler observation;
(Ii) by propagating wave to be observed in a plurality of different directions at different times, overlay the results of measuring Doppler view wave for sensing each of the wave transmitted or received by, propagate in a new direction To artificially generate the wave of the observation target , or to transmit or receive the wave for sensing each wave and superimpose it on Doppler observation,
(Iii) Doppler observation was performed by propagating the waves of the observation target in multiple different directions at the same time, and transmitting or receiving the waves for sensing the superposition of these waves, or performing Doppler observation. Filtering, separating or splitting the spectrum represented in wavenumber space or frequency space with respect to at least one wave of interest;
The measurement imaging apparatus according to any one of claims 3 to 55 , which obtains an observation result based on at least one of the above. The receiving aperture element or the signal processing unit observes audible sound waves or ultrasonic waves or shear waves using electromagnetic waves including radiation, light or microwaves, or observes audible sound waves or shear waves using ultrasonic waves . The measurement imaging device according to any one of claims 3 to 56 . The signal processing unit performs Hilbert transform approximately and at high speed by performing a differentiating process on a one-dimensional signal or a multi-dimensional signal to generate a signal having a phase difference of 90 °, instead of the process using the Fourier transform. The measurement imaging device according to any one of claims 3 to 57 . The signal processing unit obtains an instantaneous phase excluding the phase rotation related to the spatial position of the one-dimensional signal or the multi-dimensional signal and displays the phase itself, or displays by multiplying the cosine function or the sine function, or The measurement imaging apparatus according to any one of claims 3 to 58 , further performing super-resolution for weighting and displaying with an envelope of the one-dimensional signal or the multi-dimensional signal. As the non-linear processing, the signal processing unit increases or decreases the frequency of the same signal when the power is higher than 1, or lowers the frequency when the power is lower than 1. It produces harmonics that are narrowed, or in the case of multiplication between different signals, produces chords that are high-frequency, low-frequency, or wide-band, and in the case of wide-band, the effect of super-resolution. The measurement imaging device according to any one of claims 3 to 59 for obtaining. The receiving opening element or the signal processing unit, to broaden or narrow-band by performing nonlinear processing on the wave reception is signal or overlapping of a plurality of wave, separates the signal, any one of claims 3-60 The measurement imaging device according to [1]. The signal processing unit is obtained from the received signal, with respect to the angular spectrum before wave number matching or the spectrum after wave number matching, the angular spectrum or spectrum of a predetermined point spread function, or the angular spectrum obtained from the received signal or The measurement imaging apparatus according to any one of claims 3 to 61 , which performs linear supervision based on division or non-linearity based on conjugate product using a spectrum. The signal processing unit performs fixed focusing or aperture plane synthesis using a power function apodization to obtain a high-resolution point spread function and uses it to achieve focusless transmission that achieves a high frame rate. The measurement imaging apparatus according to claim 62 , which performs linear or non-linear super-resolution for increasing the resolution of a low-resolution received signal obtained by using apodization. 4. The signal processing unit performs linear processing or non-linear processing super-resolution on the received signal after beam forming, or performs beam forming after linear processing or non-linear processing super-resolution on the received signal. 63. The measurement imaging apparatus according to any one of items 63 to 63 . The signal processing unit is a state in which a plurality of received signals of different waves are superimposed, spectral frequency division, separation, or a combination thereof, a super solution based on linear processing or nonlinear processing. The measurement imaging apparatus according to any one of claims 3 to 64 , which is subjected to an image and used for imaging or measurement. The signal processing unit, by coherent addition of a plurality of super-resolution processed reception signals to further increase the resolution, or by incoherent addition of a plurality of super-resolution processed reception signals for imaging, spatial resolution The measurement imaging apparatus according to any one of claims 3 to 65 , which is used for imaging or measurement by reducing speckle while suppressing a decrease in the temperature. The signal processing section performs nonlinear processing on a plurality of received signals having different signal intensities to generate harmonics of each signal, thereby emphasizing the difference in the signal intensities for imaging, or reducing the difference in the signal intensities. in order to image Te, before or after the linear processing or based on nonlinear processing super-resolution processing by weighting the energy or specific spectrum of a plurality of received signals, or, or superimposed them of claim 3-66 The measurement imaging apparatus according to any one of items. Using a magnetic substance that has an affinity for human lesions as a contrast agent, irradiate the diagnosis site with ultrasonic waves or other mechanical waves, and perform lesion detection, diagnosis, or treatment based on magnetic field observation using a magnetic field sensor. The measurement imaging device according to any one of claims 3 to 67 . The measurement according to any one of claims 3 to 68 , wherein, in addition to the optical absorption frequency characteristic of the contrast agent, the frequency characteristic of the optical ultrasonic wave generated with respect to the irradiation light is observed using the optical ultrasonic wave. Imaging equipment. The measurement imaging apparatus according to any one of claims 3 to 69 , which includes a Fusion that simultaneously uses an ultrasonic image diagnostic apparatus and an OCT apparatus, or that also performs observation based on optical ultrasound at the same time. The measurement imaging apparatus according to any one of claims 3 to 70 , which has a Fusion function of simultaneously performing PET observation using an ultrasonic diagnostic apparatus or an optical ultrasonic apparatus. The measurement imaging device according to any one of claims 3 to 67 and 70 , which measures an absorption spectrum in OCT, and performs diagnostic imaging based on a spectroscopic method. When the observation target includes an inorganic substance and an organic substance, the terahertz wave or the X-ray is used to observe the inorganic substance, and the ultrasonic wave, the optical ultrasonic wave, the MRI wave, or the OCT wave is used to observe the organic substance, and the observation is performed. The measurement imaging device according to any one of claims 3 to 72 , which displays a result in Fusion.