CN108742528A - A kind of the fast linear cofocus scanning optoacoustic probe and its imaging method of no water coincidence - Google Patents

Abstract

The invention discloses a fast linear confocal scanning photoacoustic probe without water coupling and an imaging method. Coupler, ultrasonic transducer; the laser emitted from the fiber is collimated by the fiber collimator, reflected by the galvanometer, and then sequentially injected into the flat-field scanning lens, hollow two-dimensional translation adjustment frame, and ultrasonic coupler to reach the sample. After the sample absorbs the light, an acoustic signal is generated, which is converted into an electrical signal by the ultrasonic transducer and transmitted to the computer processing system, and then fast image reconstruction is performed through the GPU to realize real-time imaging. The advantage of the present invention is that while the high resolution is ensured by using point excitation, fast linear confocal scanning detection is realized, and the device without water coupling can achieve better results in matching the application of photoacoustic microscopy instruments.

Description

A fast linear confocal scanning photoacoustic probe without water coupling and its imaging method

technical field

The invention relates to the field of photoacoustic imaging technology and devices, in particular to a fast linear confocal scanning photoacoustic probe without water coupling and an imaging method thereof.

Background technique

Photoacoustic imaging is a new non-invasive and non-ionizing biomedical imaging method developed in recent years. When the pulsed laser is irradiated (thermoacoustic imaging specifically refers to irradiation with radio frequency pulsed laser) into biological tissue, the light absorption domain of the tissue will generate an ultrasonic signal. We call this ultrasonic signal generated by light excitation as photoacoustic Signal. The photoacoustic signal generated by biological tissue carries the light absorption characteristic information of the tissue, and the light absorption distribution image in the tissue can be reconstructed by detecting the photoacoustic signal. Photoacoustic imaging combines the advantages of high selectivity in pure optical tissue imaging and deep penetration in pure ultrasonic tissue imaging to obtain high-resolution and high-contrast tissue images, avoiding the influence of light scattering in principle, and breaking through High-resolution optical imaging depth "soft limit" (~1mm), can achieve 50mm deep in vivo tissue imaging.

Since photoacoustic imaging uses ultrasonic transducers to receive photoacoustic signals, photoacoustic signals need to pass through coupling substances from biological tissues to ultrasonic transducers. At present, most of the photoacoustic probes use water as the coupling material, but there are many disadvantages of using water as the coupling material. One is that there should be no air bubbles in the water, and a little air bubbles will cause distortion of the photoacoustic signal, which is harmful to the imaging device. The airtightness has extremely high requirements, which is difficult to achieve in engineering; second, even if the airtightness requirements can be met, the water will become dirty and deteriorate after a certain period of time, which is unavoidable, which leads to photoacoustic imaging every time Water needs to be changed before testing. This greatly increases the operational complexity of photoacoustic imaging detection.

In addition, it is difficult for traditional photoacoustic imaging systems to simultaneously achieve fast imaging and high-resolution imaging. In order to achieve fast imaging, the traditional photoacoustic imaging system uses a large spot to irradiate the sample, and uses an ultrasonic transducer array to collect signals. Although this can achieve real-time imaging, the resolution is limited by the size of the array elements, and high-resolution imaging cannot be achieved; In order to achieve high resolution, the light needs to be focused, and the resolution depends on the size of the focused spot, but when the light is focused, the light only illuminates a very small area, so light scanning is required to image the entire target area, the traditional The photoacoustic imaging system uses a motor to drive the probe or sample to move for optical scanning, but the motor has a large mass and large inertia, and it is basically impossible to achieve fast scanning. The CPU processes the data, and it is also difficult to image in real time.

Contents of the invention

The main purpose of the present invention is to overcome the shortcomings and deficiencies of the prior art, and provide a fast linear confocal scanning photoacoustic probe without water coupling. The photoacoustic probe uses a solid ultrasonic coupling material as the coupling material, which not only greatly reduces the optical The cumbersome operation of acoustic imaging detection will not affect the imaging effect.

Another object of the present invention is to provide an imaging method of a fast linear confocal scanning photoacoustic probe without water coupling, so as to realize high-resolution real-time imaging.

In order to achieve the above-mentioned first purpose, the present invention adopts the following technical solutions:

A water-free coupled fast linear confocal scanning photoacoustic probe proposed by the present invention includes a casing, an optical fiber collimator, a vibrating mirror, a flat-field scanning lens, a hollow two-dimensional translation adjustment frame, an ultrasonic coupler and an ultrasonic transducer The casing includes a pressing piece and a casing main body, and the casing main body is provided with mounting holes for respectively installing a vibrating mirror, an optical fiber collimator, a flat-field scanning lens, and a hollow two-dimensional translation adjustment frame; The ultrasonic coupler and the ultrasonic transducer are arranged on a hollow two-dimensional translation adjustment frame;

The ultrasonic coupler includes an upper part of the ultrasonic coupler, a lower part of the ultrasonic coupler and a light-transmitting sound mirror, and the light incident surface and the light exit surface of the ultrasonic coupler are all set horizontally to ensure the vertical incidence and exit of light and avoid In order to deflect the light, the light-transmitting acoustic mirror is set at an angle of 45 degrees to the horizontal direction, and is located in the middle of the upper part of the ultrasonic coupler and the lower part of the ultrasonic coupler. The upper part of the ultrasonic coupler, the light-transmitting acoustic mirror, The lower part of the ultrasonic coupler is tightly connected in turn;

The ultrasonic transducer is arranged on the lower part of the ultrasonic coupler, and after the connection is completed, the flat-field scanning lens, the hollow two-dimensional translation adjustment frame, and the ultrasonic coupler are arranged coaxially in sequence.

As a preferred technical solution, the mounting hole is configured as a threaded hole; the fiber collimator and flat-field scanning lens are threaded and connected directly through the matching threaded hole on the main body of the casing; the vibrating mirror is screwed The pressing piece with holes is pressed and fixed on the main body of the casing; the main body of the casing is connected with the hollow two-dimensional translation adjustment frame through screws at the four corners.

As a preferred technical solution, the optical fiber collimator is cylindrical, with an external thread at one end for cooperating and fixing with the threaded hole on the housing, and a threaded structure coupled with the fiber head at the other end.

As a preferred technical solution, the vibrating mirror includes a smooth coated reflective lens, a cylindrical motor that drives the lens to deflect, and a signal line. After power-on, the coated reflective lens is locked in the initial position, and the coated reflective lens is aligned with the Set at an angle of 45 degrees, so that the collimated light emitted from the fiber collimator is reflected by it and enters the flat-field scanning lens vertically. The module controls the motor to drive the lens deflection through the signal line, and the deflection angle of the lens is proportional to the amplitude of the control voltage.

As a preferred technical solution, the flat-field scanning lens has the function of focusing the light beam, so that the laser light can be focused into a very small light spot in the scanning area to achieve high resolution; the flat-field scanning lens can also solve the large-angle fan of the vibration mirror The problem that the light focus is not on the same horizontal plane caused by scanning, which makes the size of the focused spot on the periphery of the scanning area basically the same as the focused spot in the center when scanning the sample surface, thus ensuring that the lateral resolution in the entire scanning area is the best resolution ; Since the flat-field scanning lens is fixed on the casing through threads, the rotating flat-field scanning lens can realize the axial adjustment of the optical focus, thereby realizing confocal excitation and detection modes of light and sound.

As a preferred technical solution, the hollow two-dimensional translation adjustment frame is used to adjust the relative position of the center of the sound field and the light on the horizontal plane to achieve photoacoustic coaxiality; the hollow two-dimensional translation adjustment includes a hollow two-dimensional translation adjustment The frame shell, the adjusting screw and the translatable part with the hollow circular hole, the two-dimensional direction adjustment on the horizontal plane is carried out through the two adjusting screws, and the hollow circular hole of the translatable part is threaded to connect the ultrasonic coupler and the ultrasonic transducer.

As a preferred technical solution, the upper part of the ultrasonic coupler includes a shell of the upper part of the ultrasonic coupler and a first internal solid ultrasonic coupling substance; the upper half of the shell of the upper part of the ultrasonic coupler is cylindrical, with There is an external thread structure, which is used to connect with the translatable part of the hollow two-dimensional translation adjustment frame. The upper surface of the shell of the upper part of the ultrasonic coupler is a horizontal plane, and the light is vertically incident from the upper surface; the outer shell of the upper part of the ultrasonic coupler The lower half is a prism, and the lower surface is an inclined plane at an angle of 45 degrees to the horizontal direction; the axial center part of the upper part of the ultrasonic coupler is a square slot in the axial direction, and the first solid ultrasonic The coupling substance is closely connected with the shell of the upper part of the ultrasonic coupler;

The lower part of the ultrasonic coupler includes the shell of the lower part of the ultrasonic coupler and the second internal solid ultrasonic coupling substance. The shell of the lower part of the ultrasonic coupler is in the shape of a prism as a whole, and the left side of the shell is 45° from the horizontal direction. The slope of the ultrasonic coupler is matched with the lower surface of the upper part of the ultrasonic coupler; the shell of the lower part of the ultrasonic coupler has two through slots, one is located on the left side of the shell of the lower part of the ultrasonic coupler, which is an axial square through slot, and The upper part of the ultrasonic coupler is matched with the through groove, and the second solid ultrasonic coupling material matching the shape of the through groove is closely connected with the shell of the lower part of the ultrasonic coupler; Energizer matching connection.

As a preferred technical solution, the thickness of the light-transmitting acoustic mirror is less than 0.1mm, the light transmittance is above 92%, and the surface is smooth;

The first solid ultrasonic coupling substance and the second solid ultrasonic coupling substance are transparent and colorless, and the light transmittance is above 88%. The surface connected to the transducer and the surface in contact with the light-transmitting acoustic mirror are all polished to reduce the attenuation of light and sound during propagation, and the other surfaces are made of frosted surfaces to reduce the impact of external irrelevant light and sound on the experiment. influences.

As a preferred technical solution, the ultrasonic transducer includes an ultrasonic transducer housing, a matching layer, a piezoelectric material, a backing block, and a signal line, and the ultrasonic transducer housing is a prism whose size matches the lower part of the ultrasonic coupler The horizontal channel aligns the receiving/emitting end of the ultrasonic transducer with the light-transmitting sound mirror, so that the sound field is coaxial with the upper part of the ultrasonic coupler after being reflected by the light-transmitting sound mirror, and the transducer receives/transmits One end for emitting ultrasound is closely connected with the solid ultrasonic coupling material in the axial channel at the lower part of the ultrasonic coupler, the focal length parameter of the ultrasonic transducer is set so that the focal plane coincides with the surface of the solid ultrasonic coupling material at the bottom of the photoacoustic probe, and the ultrasonic The electrical signal obtained by the transducer is transmitted to the computer processing system through the signal line.

In order to achieve the above-mentioned second purpose, the present invention adopts the following technical solutions:

The imaging method of a fast linear confocal scanning photoacoustic probe without water coupling proposed by the present invention comprises the following steps:

(1) Apply a little ultrasonic coupling liquid on the surface of the sample to be tested, and stick it on the surface of the solid ultrasonic coupling material at the bottom of the photoacoustic probe;

(2) The galvanometer is powered on, and the laser emitting module emits laser light;

(3) According to the size of the A-scan signal, rotate the flat-field scanning lens, the ultrasonic coupler, and the adjusting screw of the hollow two-dimensional translation adjustment frame to adjust the relative position of the optical focus and the focal plane of the ultrasonic transducer, so as to realize the optical and acoustic co-existence. Focus and high-resolution imaging, and make the light focus just on the surface of the sample;

(4) The computer processing system synchronously triggers the signal to the vibrating mirror control module and the signal acquisition module simultaneously, so as to carry out parallel acquisition and storage of optical line scanning and photoacoustic signals;

(5) The computer processing system uses the GPU to quickly reconstruct the collected photoacoustic signals into photoacoustic images that reflect the different absorption of laser light by different structures of the sample, and perform real-time imaging.

Compared with the prior art, the present invention has the following advantages and beneficial effects:

1. A water-free coupled fast linear confocal scanning photoacoustic probe of the present invention uses a solid ultrasonic coupling material as the coupling material, which not only greatly reduces the cumbersomeness of photoacoustic imaging detection in operation, but also does not affect imaging Effect; the photoacoustic probe uses a vibrating mirror to achieve a large-scale optical scanning of more than 10mm, and the scanning speed of the vibrating mirror can fully meet the needs of real-time imaging; the use of a flat-field scanning lens can solve the optical focus caused by the large-angle fan scan of the vibrating mirror The problem of not being on the same horizontal plane makes the size of the focused spot on the periphery of the scanning area basically the same as that in the center when scanning the sample, thus ensuring high resolution in the entire scanning area.

2. The computer processing system of the present invention performs rapid image reconstruction on the photoacoustic signal transmitted by the photoacoustic probe through the GPU, realizing real-time imaging.

3. The ultrasonic transducer of the present invention adopts a reflective receiving method, and uses a light-transmitting anti-acoustic mirror to reflect the photoacoustic signal generated by the biological tissue to the ultrasonic transducer located on the side of the photoacoustic probe. Through the middle of the hollow ultrasonic transducer to irradiate the sample, compared with the way that the hollow ultrasonic transducer directly receives the photoacoustic signal, the advantage of using reflective reception is that the scanning range will not be limited by the hollow aperture of the hollow ultrasonic transducer .

4. The present invention uses a vibrating mirror instead of a motor for optical scanning, which reduces the volume, weight, cost and working noise of the photoacoustic probe.

Description of drawings

Fig. 1 is a schematic view of the front structure of a non-water coupling fast linear confocal scanning photoacoustic probe of the present invention.

Fig. 2(a) and Fig. 2(b) are front and left sectional views of a non-water-coupled fast linear confocal scanning photoacoustic probe of the present invention, respectively.

Fig. 3 is a solidworks design diagram of a water-free coupling fast linear confocal scanning photoacoustic probe of the present invention.

Fig. 4 is the result of photoacoustic imaging obtained by using the photoacoustic probe and imaging method described in the embodiment.

Among them, 1 is the casing, 1-1 is the main body of the casing, 1-2 is the pressing piece, 2 is the vibrating mirror, 2-1 is the vibrating mirror lens, 2-2 is the vibrating mirror motor, 2-3 is the vibrating mirror signal line, 3 is the fiber collimator, 4 is the flat-field scanning lens, 5 is the hollow two-dimensional translation adjustment frame, 5-1 is the shell of the hollow two-dimensional translation adjustment frame, 5-2 is the adjustment screw, and 5-3 is translational Part, 6 ultrasonic coupler, 6-1 is the upper part of the ultrasonic coupler, 6-2 is the lower part of the ultrasonic coupler, 6-1-1 is the shell of the upper part of the ultrasonic coupler, 6-2-1 is the ultrasonic coupler The shell of the lower part, 6-1-2, the first solid ultrasonic coupling material, 6-2-2 is the second solid ultrasonic coupling material, 6-3 is a light-transmitting acoustic mirror, 7 is an ultrasonic transducer, 7- 1 is the shell of the ultrasonic transducer, 7-2 is the matching layer of the ultrasonic transducer, 7-3 is the piezoelectric material of the ultrasonic transducer, 7-4 is the backing block of the ultrasonic transducer, 7-5 is the ultrasonic transducer signal line.

Detailed ways

The present invention will be further described in detail below in conjunction with the embodiments and the accompanying drawings, but the embodiments of the present invention are not limited thereto.

Example

As shown in Fig. 1, Fig. 2(a), Fig. 2(b) and Fig. 3, the present invention discloses a fast linear confocal scanning photoacoustic probe without water coupling, comprising: a casing 1, a vibrating mirror 2, an optical fiber Collimator 3, flat-field scanning lens 4, hollow two-dimensional translation adjustment frame 5, ultrasonic coupler 6 and ultrasonic transducer 7; described casing includes a pressing piece and casing main body, and described casing main body is set There are installation holes for respectively installing the vibrating mirror, the fiber collimator, the flat-field scanning lens and the hollow two-dimensional translation adjustment frame; the ultrasonic coupler and the ultrasonic transducer are arranged on the hollow two-dimensional translation adjustment frame.

The function of the casing 1 is to connect other parts; the function of the vibrating mirror 2 is to realize fast linear scanning of the laser in the sound field focusing area of the ultrasonic transducer; The divergent light emitted by the optical fiber is collimated; the function of the flat-field scanning lens 4 is to realize the confocal excitation and detection mode of light and sound; the function of the hollow two-dimensional translation adjustment frame 5 is to adjust the position of the center of the sound field; The function of the ultrasonic coupler 6 is to transmit the acoustic signal generated by the sample to the ultrasonic transducer; the function of the ultrasonic transducer 7 is to convert the acoustic signal into an electrical signal.

2(a), FIG. 2(b) and FIG. 3, more specifically, the photoacoustic probe of the present invention includes a casing main body 1-1, a pressing piece 1-2, a vibrating mirror lens 2-1, a vibrating mirror motor 2-2, galvanometer signal line 2-3, optical fiber collimator 3, flat-field scanning lens 4, hollow two-dimensional translation adjustment frame shell 5-1, adjustment screw 5-2, translatable part 5-3, ultrasonic coupling The shell 6-1-1 of the upper part of the ultrasonic coupler, the shell 6-2-1 of the lower part of the ultrasonic coupler, the first solid ultrasonic coupling substance 6-1-2, the second solid ultrasonic coupling substance 6-2-2, the light-transmitting Anti-acoustic mirror 6-3, ultrasonic transducer shell 7-1, ultrasonic transducer matching layer 7-2, ultrasonic transducer piezoelectric material 7-3, ultrasonic transducer backing block 7-4 and ultrasonic transducer Energizer signal line 7-5.

The structure of the non-water-coupled fast linear confocal scanning photoacoustic probe of the present invention is further described below:

The casing 1 includes a casing main body 1-1 and a pressing piece 1-2, and the casing main body 1-1 has four threaded holes, which are respectively used to connect the vibrating mirror 2, the optical fiber collimator 3, the flat field The scanning lens 4 and the hollow two-dimensional translation adjustment frame 5; the fiber collimator 3 and the flat-field scanning lens 4 have threads, which are directly connected through the matching threaded holes on the main body 1-1 of the casing; the vibrating mirror 2 is pressed by screws. The pressing piece 1-2 with holes is fixed on the casing main body 1-1; the casing main body 1-1 and the hollow two-dimensional translation adjustment frame 5 are connected by screws at the four corners; after the connection is completed, the flat-field scanning lens 4 It is coaxial with the hollow two-dimensional translation adjustment frame 5.

The vibrating mirror 2 is composed of a smooth coated reflective mirror 2-1, a cylindrical motor 2-2 that drives the deflection of the mirror, and a signal line 2-3. After power-on, the mirror 2-1 is locked at the initial position, and the The lens is set at an angle of 45 degrees to the horizontal, so that the collimated light emitted from the fiber collimator 3 is reflected by it and vertically incident on the flat-field scanning lens 4. After the vibrating mirror 2 is set, use the pressing sheet 1-2 to press the Tightly adjust the galvanometer 2, the galvanometer control module controls the motor 2-2 to drive the galvanometer lens 2-1 to deflect through the signal line 2-3, and the deflection angle of the galvanometer lens 2-1 is proportional to the amplitude of the control voltage. The deflection range is more than plus or minus 10 degrees, and the working frequency can reach more than 1KHz, which can realize fast line scanning of light in the range of more than 10mm.

The optical fiber collimator 3 is cylindrical, with an external thread at one end for cooperating and fixing with the threaded hole on the housing 1, and a threaded structure coupled with the fiber head at the other end.

The flat-field scanning lens 4 has the function of focusing the light beam, so that the laser light can be focused into a very small light spot in the scanning area, thus achieving high resolution; The resulting light focus is not on the same horizontal plane, which makes the size of the focused spot on the periphery of the scanning area basically the same as the focused spot in the center when scanning the sample surface, thus ensuring that the lateral resolution in the entire scanning area is the best resolution; because The flat-field scanning lens 4 is fixed on the casing 1 through threads, and the optical focus can be adjusted axially by rotating the flat-field scanning lens 4, so as to realize confocal excitation and detection modes of light and sound.

The hollow two-dimensional translation adjustment frame 5 is composed of a hollow two-dimensional translation adjustment frame housing 5-1, an adjustment screw 5-2 and a translatable part 5-3 with a hollow circular hole. Through two adjustment screws 5- 2. Two-dimensional direction adjustment on the horizontal plane. The hollow circular hole of the translatable part 5-3 has threads for connecting the ultrasonic coupler 6 and the ultrasonic transducer 7. The function of the hollow two-dimensional translation adjustment frame 5 is to adjust the relative position between the center of the sound field and the light on the horizontal plane, so as to realize photoacoustic coaxiality.

Described ultrasonic coupler 6 is made up of the upper part 6-1 of ultrasonic coupler, the bottom 6-2 two sections of ultrasonic coupler and light-transmitting acoustic mirror 6-3, and the light incident surface and light exit surface of ultrasonic coupler 6 are both It is set horizontally to ensure the vertical incidence and exit of light, and avoid the deflection of light. The light-transmitting acoustic mirror 6-3 is set at an angle of 45 degrees to the horizontal direction, and is located on the upper part of the ultrasonic coupler 6-1 of the ultrasonic coupler. 1. In the middle of the two sections of the lower part 6-2 of the ultrasonic coupler, the three are tightly connected by special glue.

The upper part 6-1 of the ultrasonic coupler is composed of the shell 6-1-1 of the upper part of the ultrasonic coupler and the first solid ultrasonic coupling substance 6-1-2 inside. The upper part of the shell 6-1-1 of the upper part of the ultrasonic coupler is a cylinder with an external thread structure, which is used to connect with the translatable part 5-3 of the hollow two-dimensional translation adjustment frame. The shell 6 of the upper part of the ultrasonic coupler The upper surface of -1-1 is a horizontal plane, and the light is incident vertically from the upper surface; the lower half of the casing 6-1-1 above the ultrasonic coupler is a prism, and the lower surface is a slope at an angle of 45 degrees to the horizontal direction; The axial part of the housing 6-1-1 at the upper part of the coupler is a square channel in the axial direction, and the first solid ultrasonic coupling substance 6-1-2 matching the shape of the channel is connected to the upper part of the ultrasonic coupler through special glue. The housings are 6-1-1 tightly connected.

The lower part 6-2 of the ultrasonic coupler is composed of the shell 6-2-1 of the lower part of the ultrasonic coupler and the second solid ultrasonic coupling substance 6-2-2 inside. The shell 6-2-1 of the lower part of the ultrasonic coupler is in the shape of a prism as a whole, and the left side of the shell 6-2-1 of the lower part of the ultrasonic coupler is an inclined plane at an angle of 45 degrees to the horizontal direction, which is aligned with the upper part of the ultrasonic coupler 6 The lower surface of -1 matches. The shell 6-2-1 of the lower part of the ultrasonic coupler has two through grooves, one is located on the left side of the shell, and is an axial square through groove, which matches the through groove of the upper part 6-1 of the ultrasonic coupler, and the shape of the through groove The matching second solid ultrasonic coupling substance 6-2-2 is tightly connected with the shell 6-2-1 of the lower part of the ultrasonic coupler through special glue; the other is a square through groove in the horizontal direction for connecting with the ultrasonic transducer 7 matching connections.

The thickness of the light-transmitting acoustic mirror 6-3 is less than 0.1mm, the light transmittance is above 92%, and the surface is smooth. The light-transmitting acoustic mirror 6-3 selected by the present invention is but not limited to a glass sheet.

The first solid ultrasonic coupling substance 6-1-2 and the second solid ultrasonic coupling substance 6-2-2 are transparent and colorless, with a light transmittance above 88%, stable physical and chemical properties, harmless to biological tissues, and acoustic impedance Between the human body tissue and the ultrasonic transducer matching layer 7-2, the light incident plane of the first solid ultrasonic coupling substance 6-1-2, the second solid ultrasonic coupling substance 6-2-2, and the surface of the contact sample The surface, the surface connected with the ultrasonic transducer 7 and the surface in contact with the light-transmitting anti-acoustic mirror 6-3 are all polished to reduce the attenuation of light and sound during propagation, and the other surfaces are all made of frosted surfaces to reduce In order to minimize the influence of external irrelevant light and sound on the experiment, the first solid ultrasonic coupling material 6-1-2 and the second solid ultrasonic coupling material 6-2-2 selected in the present invention are but not limited to polystyrene (PS).

The ultrasonic transducer 7 is composed of an ultrasonic transducer shell 7-1, an ultrasonic transducer matching layer 7-2, an ultrasonic transducer piezoelectric material 7-3, and an ultrasonic transducer backing block 7-4 Composed with the ultrasonic transducer signal line 7-5, the ultrasonic transducer shell 7-1 is a prism, the size matches the horizontal through groove of the lower part of the ultrasonic coupler 6-2, and the end of the ultrasonic transducer 7 receiving/emitting ultrasound Align the light-transmitting sound mirror 6-3 so that the sound field is coaxial with the upper part 6-1 of the ultrasonic coupler after being reflected by the light-transmitting sound mirror 6-3, and use special glue to connect the ultrasonic transducer 7 to receive/emit ultrasonic waves One end is closely connected with the second solid ultrasonic coupling substance 6-2-2 in the axial passage groove of the lower part 6-2 of the ultrasonic coupler, and the focal length parameter of the ultrasonic transducer 7 is set to be between the focal plane and the bottom of the photoacoustic probe. The surface of the second solid ultrasonic coupling substance 6-2-2 overlaps, and the electric signal obtained by the ultrasonic transducer 7 is transmitted to the computer processing system through the ultrasonic transducer signal line 7-5, and the ultrasonic transducer 7 selected by the present invention is but Not limited to line focused ultrasound transducers.

In the present invention, the flat-field scanning lens 4 , the hollow two-dimensional translation adjustment frame 5 , and the ultrasonic coupler 6 are arranged coaxially in sequence.

In this embodiment, the imaging method of the above-mentioned photoacoustic probe is applied, and the steps are as follows:

(1) Apply a little ultrasonic coupling liquid on the surface of the sample to be tested, and stick it on the surface of the second solid ultrasonic coupling substance 6-2-2 at the bottom of the photoacoustic probe;

(2) The vibrating mirror 2 is powered on, and the laser emitting module emits laser light;

(3) According to the size of the A-scan signal, rotate the flat-field scanning lens 4, the ultrasonic coupler 6 and the adjusting screw of the hollow two-dimensional translation adjustment frame 5 to adjust the relative position of the optical focus and the focal line of the line-focusing ultrasonic transducer 7 , to achieve confocal and high-resolution imaging of light and sound rays, and make the light focus just on the surface of the sample;

(4) The computer processing system synchronously triggers the signal to the vibrating mirror control module and the signal acquisition module simultaneously, so as to carry out parallel acquisition and storage of optical scanning and photoacoustic signals;

(5) The computer processing system uses the GPU to quickly reconstruct the collected photoacoustic signals into photoacoustic images that reflect the different absorption of laser light by different structures of the sample, and perform real-time imaging.

Fig. 4 is the result of photoacoustic imaging obtained by using the photoacoustic probe and imaging method described in the embodiment. The left side is the sample (XY plane), and the right side is the photoacoustic real-time tomographic slice (YZ plane) corresponding to the dotted line in the left figure. It can be seen from the resulting images that the photoacoustic probe and imaging method can obtain accurate high-resolution photoacoustic tomographic slices of carbon filaments with a diameter of 7 microns.

The above-mentioned embodiment is a preferred embodiment of the present invention, but the embodiment of the present invention is not limited by the above-mentioned embodiment, and any other changes, modifications, substitutions, combinations, Simplifications should be equivalent replacement methods, and all are included in the protection scope of the present invention.

Claims (10)

1. A fast linear confocal scanning photoacoustic probe without water coupling, characterized in that it comprises a casing, an optical fiber collimator, a vibrating mirror, a flat-field scanning lens, a hollow two-dimensional translation adjustment frame, an ultrasonic coupler and an ultrasonic Transducer; the casing includes a pressing piece and a casing main body, and the casing main body is provided with mounting holes for respectively installing a vibrating mirror, an optical fiber collimator, a flat-field scanning lens, and a hollow two-dimensional translation adjustment frame; the ultrasonic coupler and the ultrasonic transducer are arranged on a hollow two-dimensional translation adjustment frame; The ultrasonic coupler includes an upper part of the ultrasonic coupler, a lower part of the ultrasonic coupler and a light-transmitting sound mirror, and the light incident surface and the light exit surface of the ultrasonic coupler are all set horizontally to ensure the vertical incidence and exit of light and avoid In order to deflect the light, the light-transmitting acoustic mirror is set at an angle of 45 degrees to the horizontal direction, and is located in the middle of the upper part of the ultrasonic coupler and the lower part of the ultrasonic coupler. The upper part of the ultrasonic coupler, the light-transmitting acoustic mirror, The lower part of the ultrasonic coupler is tightly connected in turn; The ultrasonic transducer is arranged on the lower part of the ultrasonic coupler, and after the connection is completed, the flat-field scanning lens, the hollow two-dimensional translation adjustment frame, and the ultrasonic coupler are arranged coaxially in sequence. 2. A fast linear confocal scanning photoacoustic probe without water coupling according to claim 1, wherein the mounting hole is configured as a threaded hole; the fiber collimator and field-field scanning lens themselves have Threads are directly connected through the matching threaded holes on the main body of the case; the oscillating mirror is fixed on the main body of the case by pressing the pressing plate with holes; the main body of the case and the hollow two-dimensional translation adjustment frame pass through the four corners screw connection at the 3. A fast linear confocal scanning photoacoustic probe without water coupling according to claim 2, wherein the optical fiber collimator is cylindrical, and one end has an external thread for connecting with the casing. The threaded hole is fixed, and the other end is provided with a threaded structure coupled with the fiber optic head. 4. A fast linear confocal scanning photoacoustic probe without water coupling according to claim 1, wherein the oscillating mirror comprises a smooth coated reflective lens, a cylindrical motor and a signal line that drive the deflection of the lens, After power-on, the coated reflective lens is locked in the initial position, and the coated reflective lens is set at an angle of 45 degrees to the horizontal, so that the collimated light emitted from the fiber collimator is reflected by it and vertically incident on the flat-field scanning lens, vibrating mirror After setting, use the pressure piece to press the adjusted vibrating mirror with screws, and the vibrating mirror control module controls the motor to drive the lens deflection through the signal line. The deflection angle of the lens is proportional to the amplitude of the control voltage. 5. A fast linear confocal scanning photoacoustic probe without water coupling according to claim 1, characterized in that, the flat-field scanning lens has the function of focusing the light beam, so that the laser is focused to a minimum in the scanning area. The light spot can achieve high resolution; the flat-field scanning lens can also solve the problem that the light focus is not on the same horizontal plane caused by the large-angle fan scan of the galvanometer, which makes the focus spot size on the periphery of the scanning area different from that in the center when scanning the sample surface. The focus spot is basically the same, so as to ensure that the lateral resolution in the entire scanning area is the best resolution; because the flat-field scanning lens is fixed on the casing through threads, the optical focus can be adjusted axially by rotating the flat-field scanning lens, so that Realize optical and acoustic confocal excitation and detection modes. 6. A non-water-coupled fast linear confocal scanning photoacoustic probe according to claim 1, wherein the hollow two-dimensional translation adjustment mount is used to adjust the relative position of the center of the sound field and the light on the horizontal plane , to achieve photoacoustic coaxiality; the hollow two-dimensional translation adjustment includes a hollow two-dimensional translation adjustment frame shell, an adjustment screw and a translatable part with a hollow circular hole, and the two-dimensional direction adjustment on the horizontal plane is performed through two adjustment screws , the hollow circular hole of the translatable part is threaded for connecting the ultrasonic coupler and the ultrasonic transducer. 7. A fast linear confocal scanning photoacoustic probe without water coupling according to claim 1, characterized in that the upper part of the ultrasonic coupler comprises an outer shell of the upper part of the ultrasonic coupler and a first internal solid-state ultrasonic Coupling substance; the upper part of the shell of the upper part of the ultrasonic coupler is cylindrical with an external thread structure for connecting with the translatable part of the hollow two-dimensional translation adjustment frame, and the upper part of the shell of the upper part of the ultrasonic coupler The surface is a horizontal plane, and light is incident vertically from the upper surface; the lower half of the shell of the upper part of the ultrasonic coupler is a prism, and the lower surface is a slope at an angle of 45 degrees to the horizontal direction; the axis of the shell of the upper part of the ultrasonic coupler The core part is a square channel in the axial direction, and the first solid ultrasonic coupling material matching the shape of the channel is closely connected with the shell of the upper part of the ultrasonic coupler; The lower part of the ultrasonic coupler includes the shell of the lower part of the ultrasonic coupler and the second internal solid ultrasonic coupling substance. The shell of the lower part of the ultrasonic coupler is in the shape of a prism as a whole, and the left side of the shell is 45° from the horizontal direction. The slope of the ultrasonic coupler is matched with the lower surface of the upper part of the ultrasonic coupler; the shell of the lower part of the ultrasonic coupler has two through slots, one is located on the left side of the shell of the lower part of the ultrasonic coupler, which is an axial square through slot, and The upper part of the ultrasonic coupler is matched with the through groove, and the second solid ultrasonic coupling material matching the shape of the through groove is closely connected with the shell of the lower part of the ultrasonic coupler; Energizer matching connection. 8. A water-free coupled fast linear confocal scanning photoacoustic probe according to claim 7, characterized in that the thickness of the light-transmitting acoustic mirror is less than 0.1mm, the light transmittance is above 92%, and the surface is smooth ; The first solid ultrasonic coupling substance and the second solid ultrasonic coupling substance are transparent and colorless, and the light transmittance is above 88%. The surface connected to the transducer and the surface in contact with the light-transmitting acoustic mirror are all polished to reduce the attenuation of light and sound during propagation, and the other surfaces are made of frosted surfaces to reduce the impact of external irrelevant light and sound on the experiment. influences. 9. A fast linear confocal scanning photoacoustic probe without water coupling according to claim 1, wherein the ultrasonic transducer comprises an ultrasonic transducer shell, a matching layer, a piezoelectric material, a backing block and signal line, the ultrasonic transducer shell is a prism, the size matches the horizontal through groove of the lower part of the ultrasonic coupler, and the end of the ultrasonic transducer receiving/emitting ultrasonic is aligned with the light-transmitting sound mirror, so that the sound field passes through the The optical anti-acoustic mirror is coaxial with the upper part of the ultrasonic coupler after reflection, and the end of the transducer receiving/transmitting ultrasound is closely connected with the solid ultrasonic coupling material in the axial channel at the lower part of the ultrasonic coupler. The ultrasonic transducer The focal length parameter is set so that the focal plane coincides with the surface of the solid ultrasonic coupling material at the bottom of the photoacoustic probe, and the electrical signal obtained by the ultrasonic transducer is transmitted to the computer processing system through the signal line. 10. The imaging method of the fast linear confocal scanning photoacoustic probe without water coupling according to any one of claims 1-9, characterized in that, comprising the steps of: (1) Apply a little ultrasonic coupling liquid on the surface of the sample to be tested, and stick it on the surface of the solid ultrasonic coupling material at the bottom of the photoacoustic probe; (2) The galvanometer is powered on, and the laser emitting module emits laser light; (3) According to the size of the A-scan signal, rotate the flat-field scanning lens, the ultrasonic coupler, and the adjusting screw of the hollow two-dimensional translation adjustment frame to adjust the relative position of the optical focus and the focal plane of the ultrasonic transducer, so as to realize the optical and acoustic co-existence. Focus and high-resolution imaging, and make the light focus just on the surface of the sample; (4) The computer processing system synchronously triggers the signal to the vibrating mirror control module and the signal acquisition module simultaneously, so as to carry out parallel acquisition and storage of optical line scanning and photoacoustic signals; (5) The computer processing system uses the GPU to quickly reconstruct the collected photoacoustic signals into photoacoustic images that reflect the different absorption of laser light by different structures of the sample, and perform real-time imaging.