CN113842158B - Photoacoustic/ultrasound endoscopic probe and dynamic focus reconstruction algorithm based on fixed-focus sound field - Google Patents

Abstract

The invention relates to the field of endoscopic imaging and discloses a photoacoustic/ultrasonic endoscopic probe based on a fixed Jiao Shengchang and a dynamic focusing reconstruction algorithm, which comprises the following steps of 1) determining an equivalent focusing sound field and an equivalent focus of a transducer according to inherent parameters of the transducer; 2) The equivalent focus is taken as a reference point, the path length of a signal fed back by the equivalent focus received by the transducer is determined to be F, and the equivalent beam waist radius omega of the sound field collected by the transducer is determined ₀ And equivalent half depth of focus Z ₀ The method comprises the steps of carrying out a first treatment on the surface of the 3) According to the parameters, calculating the pixel value of a single pixel point obtained by scanning of the transducer, and processing the pixel point through a delay superposition algorithm to obtain a final image. The invention optimizes the conventional time delay superposition algorithm to obtain a novel time delay superposition algorithm, and adopts a novel endoscopic probe, and the endoscopic probe is combined with the algorithm for use, so that the imaging definition and accuracy of final imaging can be improved on the premise of ensuring the imaging speed.

Description

Photoacoustic/ultrasound endoscopic probe and dynamic focus reconstruction algorithm based on fixed-focus sound field

Technical field

The invention relates to the field of endoscopic imaging, and specifically to a photoacoustic/ultrasonic endoscopic probe based on a fixed-focus sound field and a dynamic focus reconstruction algorithm.

Background technique

Acoustic focusing photoacoustic endoscopic imaging is an emerging biomedical endoscopic imaging method that integrates high resolution, high penetration depth, and high optical contrast. In many sound-focused photoacoustic endoscopic imaging systems, since a transducer based on the piezoelectric effect can be used to receive ultrasound, and this transducer can also emit ultrasound, photoacoustic/ultrasound imaging uses the same transducer. The devices can be easily integrated together to form an acoustic focusing photoacoustic/ultrasonic imaging system. Photoacoustic/ultrasound imaging has good application prospects in specific occasions.

In conventional photoacoustic/ultrasonic endoscopic imaging probes, its basic structure allows it to perform 360-degree circular scanning imaging. In addition, a planar ultrasonic transducer can also be used, and then parabolic ultrasonic and laser reflectors can be used to form a focused sound field. When imaging such systems, the photoacoustic and ultrasonic endoscopic imaging algorithms are relatively similar. They generally use a linear propagation model of the ultrasonic beam commonly used in B-ultrasound, which is calculated directly based on the distance of the pixel relative to the transducer and the speed of sound. The delay time and the rotation angle of the transducer during endoscopic scanning are used to arrange and combine the obtained data into a sector-shaped image. Among them, since ultrasound involves the round trip of signals, the sound speed needs to be set to half of the actual sound speed during ultrasound imaging.

This imaging method is simple and direct, but due to the application of a fixed-focus probe, it can only obtain the best lateral resolution at the focus position, including the best resolution in the tangential direction and along the axis of the probe, while far away from the focus area, its lateral resolution will decrease rapidly. When the numerical aperture of the ultrasonic sensor is larger, its optimal lateral resolution is smallest, but in this case its imaging depth of field is also smaller, and vice versa. This current situation is mainly caused by the fact that the current acoustic focused photoacoustic/ultrasonic endoscopic imaging algorithm does not take into account the focused sound field of the actual transducer. Therefore, a new algorithm is urgently needed to consider the sound field of the transducer, so that The defocused area can also have higher lateral resolution, thereby ensuring that the overall image imaging is clear and accurate.

Contents of the invention

The problem to be solved by the present invention is to provide a photoacoustic/ultrasonic endoscopic dynamic focus reconstruction algorithm based on a fixed-focus sound field. This method can improve the lateral resolution of the defocused area and make the imaging clearer and more accurate.

A further problem to be solved by the present invention is to provide a photoacoustic/ultrasonic endoscopic probe based on a fixed-focus sound field, which can improve the lateral resolution of the defocused area and make the imaging clearer and more accurate.

In order to solve the above technical problems, the present invention provides a photoacoustic/ultrasonic endoscopic probe and dynamic focus reconstruction algorithm based on a fixed-focus sound field, which includes the following steps: 1) Determine the transducer according to the inherent parameters of the transducer The equivalent focused sound field and equivalent focus; 2) Taking the equivalent focus as the reference point, determine the path length traveled by the equivalent focus feedback signal received by the transducer as The equivalent beam waist radius ω ₀ and the equivalent half focal depth Z ₀ of the sound field gathered by the transducer; 3) According to the above parameters, calculate the pixel value of a single pixel scanned by the transducer, and superimpose the original delay The algorithm is optimized to obtain a new delay superposition algorithm. Through this new delay superposition algorithm, the scanned image pixels are processed, and the duration of the ultrasonic signal corresponding to the pixel received by the transducer is calculated. Sort to get the final image.

Preferably, in step 3, the final image is obtained through the following formula:

in, is the number of directional positions scanned by the transducer,/> are the pixel coordinates that need to be reconstructed,/> For the transducer in Chapter/> The signal received by the transducer at the position,/> is time,/> For the first/> The phase coefficient of the position of the pixel point,/> For the first/> The weight coefficient of the position of each pixel. Through this optimal technical solution, the traditional delay superposition algorithm is optimized to obtain a new delay superposition algorithm. The delay superposition algorithm can be derived through simple calculations to obtain the final image data, and through the calculation of this superposition algorithm, The required calculation time is shorter and the efficiency is higher, and this algorithm not only ensures the calculation efficiency, but also improves the clarity of imaging, making the final imaging clearer and more accurate.

Further preferably, the phase coefficient is determined by the relative position of the pixel point and the focus of the transducer. In photoacoustic imaging, the phase coefficient is:

In ultrasound imaging, the phase coefficient is:

in, is the propagation speed of ultrasonic waves in the medium,/> is the axial distance of the pixel point relative to the focus of the transducer, and b is the radial distance of the pixel point relative to the focus of the transducer. Through this preferred technical solution, by limiting the phase coefficients of photoacoustic imaging and ultrasonic imaging, the device can more accurately locate the relative positional relationship between the pixels and the focus of the transducer when performing photoacoustic imaging and ultrasonic imaging. , thereby improving imaging accuracy.

Preferably, the axial distance between the pixel point and the focus of the transducer The expression is as follows:

in, For the transducer in Chapter/> The focus when position,/> For the transducer/> the center of rotation at the position. Through this preferred technical solution, the axial distance between the pixel point and the focus of the transducer is determined, thereby improving the accuracy of imaging of the image pixel point in the direction of the axial distance.

Further preferably, the expression of the radial distance b between the pixel point and the focus of the transducer is as follows:

in, For the transducer in Chapter/> The focus when position,/> For the transducer/> the center of rotation at the position. Through this preferred technical solution, the radial distance between the pixel point and the focus of the transducer is determined, thereby improving the accuracy of imaging of the image pixel point in the direction of the radial distance.

Preferably, the For the first/> The weight coefficient of the position of a pixel, which can be calculated by the following formula:

in, is a position restriction function determined by the distance between the current pixel and the transducer. Through this preferred technical solution, the weight coefficient is limited by the position restriction function, which can further limit the position of the pixels, thereby more accurately determining the relative position of the pixels, thereby ensuring the accuracy of the superimposed image.

Further preferably, the position limitation function limits the range of delay superposition in the following manner:

Among them, a ₁ , a ₂ , b ₁ and b ₂ are the limiting parameters of the position limiting function. The limiting parameters are calculated by the following formula:

,

,/> ,

Among them, D is the diameter of the endoscopic probe, and R is the radius of the imaging area. Through this preferred technical solution, limiting parameters are introduced to further limit the range of delay superposition, and the limiting parameters are combined with the intrinsic parameters of the probe and the final imaging parameters, thereby improving the practicality of the limiting function and enabling the limiting function to Accurately limit the range of time-lapse superposition, thereby improving the accuracy of the image after time-lapse superposition.

The second aspect of the present invention provides a photoacoustic/ultrasonic endoscopic probe based on a fixed-focus sound field, including: a transparent shell, a calcium fluoride lens, a reflector, a protective structure and a transducer. The endoscopic probe is driven by a rotating motor Its movement is driven to complete the lateral annular scanning imaging operation. The transparent shell is wrapped around the outer surface of the endoscopic probe, and the sound waves emitted by the transducer are refracted and focused by the calcium fluoride lens and reflector. When illuminated on the detection object, the endoscopic probe can implement a photoacoustic/ultrasonic endoscopic dynamic focus reconstruction algorithm based on a fixed-focus sound field provided by the first aspect of the present invention.

Preferably, the transducer adopts a flat-field ultrasonic transducer. Through this preferred technical solution, a flat-field ultrasonic transducer is used, which has a more uniform sound field and is less difficult to manufacture than a focused ultrasonic transducer. The receiving surface is flat, which facilitates the reception of acoustic signals fed back from various positions. , thereby improving the clarity of the final image.

Further preferably, the reflector may be a parabolic reflector, and the arc height of the parabolic reflector is used as a reference line, and the reference line is perpendicular to the center of the calcium fluoride lens. Through this preferred technical solution, the parabolic reflector makes the transducer and the focusing point mirror symmetrical with respect to the center of the parabolic reflector, and the reflector can achieve photoacoustic and ultrasonic reflection, making the device universally applicable to various applications. Photoacoustic and ultrasound examinations.

Through the above technical solution, the photoacoustic/ultrasound endoscopic dynamic focus reconstruction algorithm provided by the present invention based on the fixed-focus sound field optimizes the conventional delay superposition algorithm, optimizes and limits the parameters, and introduces limiting parameters, thereby A new type of delayed superposition algorithm is obtained. Through this new delayed superposition algorithm, the imaging clarity and accuracy of the final imaging can be improved while ensuring the imaging speed.

The present invention also provides a photoacoustic/ultrasonic endoscopic probe based on a fixed-focus sound field. By using a planar ultrasonic transducer and a parabolic reflector to work, the universal applicability of the device is improved, and the device can receive signals from various sources. The angle feeds back the acoustic signal, thereby increasing the clarity and accuracy of its final imaging.

Other features and advantages of the present invention will be described in detail in the detailed description that follows.

Description of the drawings

Figure 1 is a structural diagram and a scanning equivalent structural diagram of an acoustic focusing photoacoustic endoscopic probe used in the prior art;

Figure 2 is a structural diagram and a scanning equivalent structural diagram of the acoustic focusing photoacoustic endoscopic probe based on parabolic reflectors used in the present invention;

Figure 3 is a schematic structural diagram of the reflector used in the present invention;

Figure 4 is a structural diagram of an object scanned by the present invention;

Figure 5(a) and (b) are photoacoustic result diagrams comparing the algorithm of the present invention and the original algorithm respectively;

Figures 6(a) and (b) are respectively ultrasound result diagrams comparing the algorithm of the present invention with the original algorithm.

Reference signs

1 Transparent shell 2 Hollow sound focused ultrasound transducer

3Multimode fiber 4Top 45 degree reflector

5 calcium fluoride lenses 6 reflectors

7 Protective structure 8 Flat field ultrasonic transducer

Detailed ways

Specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described here are only used to illustrate and explain the present invention, and are not intended to limit the present invention.

In the description of the present invention, it should be noted that, unless otherwise clearly stated and limited, the terms "installation", "setting" and "connection" should be understood in a broad sense. For example, the term "connection" can mean a fixed connection, or a fixed connection. It can be a detachable connection or an integral connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be an internal connection between two elements or an interactive relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

An embodiment of the present invention's photoacoustic/ultrasonic endoscopic probe and dynamic focus reconstruction algorithm based on a fixed-focus sound field, including the following steps: 1) Determine the equivalent focus of the transducer according to the inherent parameters of the transducer Sound field and equivalent focus; 2) Taking the equivalent focus as the reference point, determine the path length traveled by the signal fed back by the equivalent focus received by the transducer as F, and determine the length of the sound field gathered by the transducer. Equivalent beam waist radius ω ₀ and equivalent half focal depth Z ₀ ; 3) According to the above parameters, calculate the pixel value of a single pixel scanned by the transducer, and optimize the original delay superposition algorithm, A new type of delay superposition algorithm is obtained. Through this new type of delay superposition algorithm, the scanned image pixels are processed and sorted according to the time length of the ultrasonic signal corresponding to the pixel received by the transducer, thereby Get the final image.

Compared with the existing algorithm, the present invention not only considers the actual shape of the focused sound field, but also achieves dynamic focusing of the endoscopic probe in the tangential direction by delaying superposition and reconstruction of signals collected at multiple transducer positions, thereby achieving Effectively expand the depth of field of its imaging, thereby obtaining all-round high-resolution acoustic focused photoacoustic endoscopic imaging results.

In some embodiments of the photoacoustic/ultrasonic endoscopic probe and dynamic focus reconstruction algorithm based on the fixed-focus sound field of the present invention, in step 3, the data parameters obtained in the above steps 1 and 2 are used to obtain the final result through the following formula image:

in, is the number of directional positions scanned by the transducer,/> are the pixel coordinates that need to be reconstructed,/> For the transducer in Chapter/> The signal received by the transducer at the position,/> is time,/> For the first/> The phase coefficient of the position of the pixel point,/> For the first/> The weight coefficient of the position of each pixel.

Among them, the phase coefficient is determined by the relative position of the pixel point and the focus of the transducer. In photoacoustic imaging, the phase coefficient is:

In ultrasound imaging, the phase coefficient is:

in, is the propagation speed of ultrasonic waves in the medium,/> is the axial distance of the pixel point relative to the focus of the transducer, b is the radial distance of the pixel point relative to the focus of the transducer, and is the axial distance of the pixel point from the focus of the transducer/> and the expression of radial distance b is as follows:

in, For the transducer in Chapter/> The focus when position,/> For the transducer/> the center of rotation at the position, For the first/> The weight coefficient of the position of a pixel, which can be calculated by the following formula:

in, It is a position limitation function determined by the distance between the current pixel and the transducer. The position limitation function limits the range of delay superposition in the following ways:

Among them, a ₁ , a ₂ , b ₁ and b ₂ are the limiting parameters of the position limiting function. The limiting parameters are calculated by the following formula:

,

,/> ,

Among them, D is the diameter of the endoscopic probe, and R is the radius of the imaging area. It can be seen from the above endoscopic imaging algorithm that compared with the existing imaging algorithms in use, the new delayed superposition algorithm used in the present invention is optimized based on the conventional delayed superposition algorithm, thereby obtaining a new The new delay superposition algorithm not only retains the traditional delay superposition algorithm's effects of fast calculation speed and high imaging efficiency in imaging, but also improves the clarity of the final imaging, thus making it possible to use the algorithm of the present invention In the field of endoscopic imaging, it can not only ensure imaging efficiency, but also improve the clarity and accuracy of imaging.

As shown in Figure 1, the endoscopic imaging probe used by the existing endoscopic imaging algorithm includes a transparent shell 1, a hollow acoustic focusing ultrasonic sensor 2, a multimode optical fiber 3, and a top 45-degree reflector 4 components, which are used to reflect light and ultrasound. During scanning, as the top mirror 6 rotates, it can perform lateral annular scanning imaging.

In Figure 1, the equivalent beam waist radius ω ₀ and the equivalent half focal depth Z ₀ are obtained using the following formulas:

,/> ,/>

in is the center frequency of the endoscopic probe,/> is the numerical aperture of the transducer.

As shown in the figure, L1 represents the distance between the hollow focused ultrasonic sensor and the center of the reflector 6, and L2 represents the distance between the center of the reflector 6 and the focus of the hollow focused ultrasonic sensor. In the ordinary acoustic focusing photoacoustic endoscopic reconstruction algorithm , which usually adopts a linear propagation model of the ultrasonic beam similar to that used in B-ultrasound imaging. In this algorithm, any point on the image represented by polar coordinates The reconstruction value of is determined only by the signal of a single detector:

in Shown in/> The signal received by the transducer at the angle,/> is the propagation speed of ultrasound in the medium. However, since it does not consider the size and shape of the detection surface of the ultrasonic sensor, it can only obtain the best resolution result at the focused position.

As shown in Figures 2 to 3, it is an endoscopic imaging probe used in the endoscopic imaging algorithm of the present invention. The probe includes a transparent shell 1, a calcium fluoride lens 5, a reflector 6, a protective structure 7 and a flat surface. The field ultrasonic transducer 8 and the probe as a whole move under the drive of the rotating motor and complete the lateral circular scanning imaging operation. In the figure, L3 represents the distance between the flat field ultrasonic sensor 8 and the center of the calcium fluoride lens 5. L4 represents the distance between the center of the calcium fluoride lens 5 and the center of the reflector 6, and L5 represents the focal length of the parabolic reflector 6. During scanning, due to the existence of the reflector 6, it is equivalent to the flat-field ultrasonic sensor 8 being located at the dotted line in the figure. The marked mirror position, and the reflector 6 realizes the function of the acoustic lens, so the sound field at the rear end of the reflector 6 is a focused sound field, as shown in Figure 2. Therefore, during the scanning process, it is the same as that used in the existing algorithm. In comparison with the endoscopic imaging equipment, it is equivalent to the hollow focused ultrasonic sensor 2 in the existing endoscopic imaging equipment performing rotational scanning around the rotation center on a scanning path with a radius of L3+L4.

The calcium fluoride lens 5 can transmit light and reflect sound. When performing photoacoustic detection and using pulse laser to scan the tissue, the pulse laser can shine through the calcium fluoride lens 5 onto the reflector 6. The reflector 6 6 is a customized parabolic reflector 6. The parabolic reflector 6 can reflect light, sound and ultrasound. When the pulse laser passes through the calcium fluoride lens 5 and irradiates the parabolic reflector 6, the pulse laser passes through the parabolic reflector 6. Focusing, converging the pulsed laser at the equivalent focus of the focused sound field, and thereby determining the equivalent beam waist radius of the focused sound field and equivalent half-focal depth Z ₀ . When the pulse laser acts on the tissue, the irradiated tissue responds quickly, and the fed-back ultrasonic signal is received by the flat-field ultrasonic transducer 8 , thereby providing specific feedback information data. parameter.

When performing ultrasonic detection, the flat-field ultrasonic transducer 8 emits ultrasound for detection. The emitted ultrasound is refracted by the light-transmitting and sound-reflecting calcium fluoride lens 5. The refracted ultrasound is focused again by the parabolic reflector 6. Finally, Acting on the tissue, the tissue is affected by ultrasound and feedbacks an ultrasound signal. The ultrasound signal is finally received by the flat-field ultrasound transducer 8, and specific feedback information parameters are obtained.

Taking the situation shown in Figure 4 as an example, the diameter of the hollow area of this detection background is 5mm, the overall peripheral diameter is 23mm, and there are 9 point targets evenly distributed at positions from 3mm to 11mm in the x direction. The diameter of the transducer used for collection is 10mm, the focal length is 20mm, and the distance L5 from the focus to the center of rotation is 7mm. The focused ultrasonic sensor has a center frequency of 15MHz and a bandwidth of 75%.

Figure 5(a) is the photoacoustic image obtained using the original acoustic focusing photoacoustic endoscopic algorithm. The target at the 7mm position has the highest lateral resolution. The further away from the focus area, the greater the lateral resolution expansion of the target. The system Depth of field is very limited.

Figure 5(b) is a photoacoustic image obtained by using the photoacoustic endoscopic dynamic focus reconstruction algorithm based on fixed-focus sound field in the present invention. Comparing Figure 5(a), it can be seen that the algorithm of the present invention is used to remove the 7mm position target. Except that the lateral resolution is not much different from that in Figure 5(a), the lateral resolution of the other targets in the figure has been significantly improved. From this, it can be seen that the algorithm used in the present invention can produce more obvious results in photoacoustic imaging. improve.

Figure 6(a) is an ultrasound image obtained using the original acoustic focusing photoacoustic endoscopic algorithm. The lateral resolution of the target at the 7mm position is the highest. The farther away from the focus area, the greater the lateral resolution expansion of the target, and the depth of field of the system. Very restricted.

Figure 6(b) is an ultrasonic image obtained by using the fixed-focus sound field-based ultrasonic endoscopic dynamic focus reconstruction algorithm of the present invention. Comparing Figure 6(a), it can be seen that the lateral resolution of the 7mm position target is reduced by using the algorithm of the present invention. Except that the ratio is not much different from that in Figure 6(a), the lateral resolution of the remaining targets in the figure has been significantly improved. From this, it can be seen that the algorithm used in the present invention can produce a relatively obvious improvement in the field of ultrasound imaging.

Through the above dynamic focus reconstruction algorithm of photoacoustic/ultrasound endoscopy based on fixed-focus sound field, it can be clearly seen that this algorithm has universal applicability in different system structures, and in photoacoustic and ultrasonic endoscopy experiments, it retains Under the premise of lateral resolution of the focal area, the lateral resolution of the defocused area is significantly improved, resulting in a clearer and more accurate final image.

In the description of the present invention, reference to the description of the terms "one embodiment," "some embodiments," "an implementation," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in In at least one embodiment or example of the present invention. In the present invention, schematic expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

The preferred embodiments of the present invention are described in detail above with reference to the accompanying drawings, but the present invention is not limited thereto. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, including the combination of specific technical features in any suitable manner. In order to avoid unnecessary repetition, the present invention describes various possible combinations. No further explanation will be given. However, these simple modifications and combinations should also be regarded as the disclosed content of the present invention, and all belong to the protection scope of the present invention.

Claims (7)

1. A photoacoustic/ultrasonic endoscopic dynamic focusing reconstruction algorithm based on a stator Jiao Shengchang, which is characterized by comprising the following steps of:

1) Determining an equivalent focusing sound field and an equivalent focus of the transducer according to inherent parameters of the transducer;

2) The equivalent focus is taken as a reference point, the path length of the signal fed back by the equivalent focus received by the transducer is determined to be F, and the equivalent beam waist radius omega of the sound field gathered by the transducer is determined ₀ And equivalent half depth of focus Z ₀ ；

3) According to the parameters, calculating the pixel value of a single pixel point obtained by scanning the transducer, optimizing an original delay superposition algorithm to obtain a novel delay superposition algorithm, processing the scanned image pixel point by the novel delay superposition algorithm, and sequencing the ultrasonic signals corresponding to the pixel point received by the transducer according to the time length of the ultrasonic signals corresponding to the pixel point, so as to obtain a final image, wherein the final image is obtained by the following formula:

wherein,for the number of directional positions scanned by the transducer, +.>For pixel coordinates that need to be reconstructed, +.>In the (th)>Signals received by the transducer at the individual positions, +.>For time (I)>Is->Phase coefficient of the position of each pixel point, < ->Is->The weight coefficient of the position of each pixel point, wherein,

the phase coefficient is determined by the relative position of the pixel point and the focus of the transducer, and in photoacoustic imaging, the phase coefficient is as follows:

in ultrasound imaging, the phase coefficients are:

wherein,for the propagation speed of ultrasound in the medium, +.>And b is the radial distance of the pixel point relative to the focus of the transducer, wherein,

the saidIs->The weight coefficient of the position of each pixel can be calculated by the following formula:

wherein,is a position limiting function determined by the distance between the current pixel point and the transducer, and the position limiting function limits the range of the delay superposition by the following modes:

wherein a is ₁ 、a ₂ 、b ₁ And b ₂ Is a limiting parameter of the position limiting function.

2. The substrate according to claim 1The photoacoustic/ultrasonic endoscopic dynamic focusing reconstruction algorithm according to determination Jiao Shengchang is characterized in that the axial distance between the pixel point and the focus of the transducerThe expression of (2) is as follows:

wherein,in the (th)>Focal point at each position, +.>For transducer->Center of rotation at each position.

3. The photoacoustic/ultrasonic endoscopic dynamic focusing reconstruction algorithm based on the determination Jiao Shengchang according to claim 1, wherein the expression of the radial distance b of the pixel point from the transducer focus is as follows:

wherein,in the (th)>Focal point at each position, +.>For transducer->Center of rotation at each position.

4. The photoacoustic/ultrasonic endoscopic dynamic focusing reconstruction algorithm based on determination Jiao Shengchang according to claim 1, wherein said limiting parameter is calculated by the following formula:

，

， /> ，

wherein D is the diameter of the endoscopic probe, and R is the radius of the imaging region.

5. A photoacoustic/ultrasound endoscope probe based on a stator Jiao Shengchang, comprising: transparent shell, calcium fluoride lens, speculum, protection architecture and transducer, the endoscopic probe is driven its motion by rotating electrical machines, transparent shell parcel is in the surface of endoscopic probe, the signal wave that the transducer transmitted shines on the speculum through calcium fluoride lens to through the focus of speculum, shine on the probe, just endoscopic probe can realize the optoacoustic/supersound endoscopic dynamic focus rebuilding algorithm based on deciding Jiao Shengchang of any one of claims 1~ 4.

6. The constant Jiao Shengchang based photoacoustic/ultrasound endoscope probe according to claim 5, wherein said transducer is a flat field ultrasound transducer.

7. The constant Jiao Shengchang-based photoacoustic/ultrasonic endoscope probe of claim 5, wherein the reflecting mirror is a parabolic reflecting mirror and wherein the parabolic reflecting mirror is based on an arc height, the reference line being perpendicular to the center of the calcium fluoride lens.