Fast linear confocal scanning photoacoustic microscopic imaging system and imaging method thereof

Abstract

The invention discloses a fast linear confocal scanning photoacoustic microscopic imaging system and an imaging method thereof.The imaging system comprises a laser emitting module, a linear confocal scanning photoacoustic probe module and a system control and signal processing module, and optical fibers are made to resonate by controlling a piezoelectric displacement table; the electric control rotary table is controlled to repeat the scanning at small angles gradually and rotate to 180 degrees to complete full scanning of the surface of the sample, the sample generates an acoustic signal after absorbing the laser, the acoustic signal is received by the hollow line focusing transducer and converted into an electric signal, and the electric signal is transmitted to a computer for signal processing and image reconstruction. Through the linear confocal principle, the rapid and stable scanning of the sample is realized, and the imaging sensitivity is ensured while the miniaturization of the probe is optimized.

Description

Technical Field

[0001] The invention relates to the field of photoacoustic imaging technology and devices, and in particular to a fast linear confocal scanning photoacoustic microscopy imaging system and an imaging method thereof. Background Art

[0002] Photoacoustic imaging is a new biomedical imaging technology that combines the advantages of high contrast of optical imaging and deep penetration of ultrasonic imaging. When biological tissue absorbs the energy of laser irradiation, it will generate ultrasonic waves due to thermoelastic expansion. These ultrasonic waves are then detected by the ultrasonic transducer and converted into electrical signals. Through signal processing and image reconstruction algorithms, images reflecting the internal structure and function of the tissue are formed. The good spatial resolution and deep imaging depth make photoacoustic imaging technology have great development prospects in biomedical imaging.

[0003] Although photoacoustic imaging technology has significant advantages, existing technologies still face some challenges and limitations in practical applications. For example, to ensure resolution, traditional photoacoustic microscopes usually use single-point focusing raster scanning to achieve comprehensive imaging of samples through different mechanical or optical scanning methods. However, this single-point focusing scanning method is time-consuming and difficult to meet the needs of dynamic monitoring of biological processes. In addition, using a large spot to irradiate the sample can increase the scanning speed, but the imaging resolution is low and is limited by the size of the transducer array element, which is not conducive to system miniaturization and cost saving.

[0004] An existing waterless coupling fast linear confocal scanning photoacoustic probe and its imaging method (CN108742528A) use a galvanometer to realize fast linear scanning of the laser in the acoustic field focusing area of ​​the ultrasonic transducer, and use waterless coupling materials to reduce the cumbersomeness of the imaging operation, but the disadvantage is that the acoustic field space needs to accommodate other components, resulting in a certain loss of acoustic signals, and the sensitivity is subject to the acoustic reception efficiency and the acoustic numerical aperture; a new scanning method and device for an optical resolution photoacoustic microscope (CN106769876A) use a linear confocal signal generation and collection method to improve the imaging signal-to-noise ratio and sensitivity and ensure image quality, but the laser scanning and acoustic signal reception are driven by two sets of controller systems, and the laser scanning area of ​​the two-dimensional scanning galvanometer and the acoustic focal area of ​​the ultrasonic transducer need to be adjusted separately to ensure the overlap between the two, which limits the imaging speed and the miniaturization of the device. Summary of the invention

[0005] 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 microscopy imaging system and imaging method. By controlling the coordinated movement of a piezoelectric displacement stage and an electrically controlled rotating stage, the linear confocal principle is utilized to linearly scan a light beam over a sample to be tested to generate a photoacoustic signal, which is received by a hollow line focusing transducer and reconstructed by computer processing, thereby realizing fast scanning imaging of the image, ensuring high sensitivity and high signal-to-noise ratio of the imaging, and further improving the miniaturization of the system.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A fast linear confocal scanning photoacoustic microscopy imaging system comprises a laser emission module, a linear confocal scanning photoacoustic probe module and a system control and signal processing module; the laser emission module generates a light beam, which is emitted through an optical fiber and enters the linear confocal scanning photoacoustic probe module; the linear confocal scanning photoacoustic probe module controls the probe to rotate and quickly scan a sample to be tested to generate a photoacoustic signal, and converts the acoustic signal into an electrical signal, which is transmitted to the system control and signal processing module for data processing and image reconstruction.

[0008] Furthermore, the laser emission module includes a pulse laser, a neutral density filter, a fiber coupler and an optical fiber; the light beam generated by the pulse laser passes through the neutral density filter and enters the fiber coupler, and then enters the linear confocal scanning photoacoustic probe module through the optical fiber.

[0009] Further, the linear confocal scanning photoacoustic probe module includes a fiber collimator, an electrically controlled rotating stage, a piezoelectric displacement stage, an objective lens group, a hollow line focusing transducer, a probe housing and a water tank;

[0010] The piezoelectric displacement stage controls the resonant swing of the optical fiber, and cooperates with the electrically controlled rotating stage to control the rotation of the probe, quickly scanning the sample to be tested to generate photoacoustic signals. At the same time, the system controls and triggers the laser in the laser emission module of the signal processing module, and controls the movement of the piezoelectric displacement stage and the electrically controlled rotating stage.

[0011] The optical fiber collimator is arranged at the end of the optical fiber. After the laser emitted by the optical fiber collimator is focused by the objective lens group, it is irradiated on the sample to be tested placed in the water tank through the hollow line focusing transducer to generate a photoacoustic signal.

[0012] Furthermore, the probe housing is fixed to a hollow electrically controlled rotating table, the piezoelectric displacement table is fixed in the probe housing, and the probe housing, the electrically controlled rotating table, and the piezoelectric displacement table are assembled into one by a threaded structure;

[0013] The electrically controlled rotating stage uses the probe as the rotating axis and has a through hole in the center. The piezoelectric displacement stage drives the optical fiber at high frequency to produce resonance, causing the optical fiber to swing rapidly and evenly on a certain axis. The electrically controlled rotating stage rotates to the next axis to repeat the scan. The electrically controlled rotating stage and the piezoelectric displacement stage move in coordination to adjust the scanning area to achieve full scanning of the sample surface.

[0014] Furthermore, the piezoelectric displacement stage comprises a piezoelectric driver, a friction rod and a slider, two ends of the friction rod are respectively connected to the piezoelectric driver and the slider, and the slider is connected to the optical fiber.

[0015] Furthermore, the hollow line focusing transducer comprises a hollow cylindrical backing layer and a pair of symmetrically arranged high-frequency piezoelectric elements, and the high-frequency piezoelectric elements are attached to the concave surface at the bottom of the hollow cylindrical backing layer.

[0016] Furthermore, the laser area of ​​the optical fiber resonance scanning is always located within the acoustic focusing area of ​​the hollow wire focusing transducer, and the hollow wire focusing transducer converts the photoacoustic signal into an electrical signal and transmits it to the system control and signal processing module.

[0017] Furthermore, the system control and signal processing module includes an amplifier, a low-pass filter, a field programmable gate array and a computer; the electrical signal converted by the hollow line focusing transducer of the linear confocal scanning photoacoustic probe module is amplified by the amplifier, and then filtered by the low-pass filter and transmitted to the computer for photoacoustic signal processing and image reconstruction.

[0018] Furthermore, the field programmable gate array, computer, and pulse laser of the laser emission module are connected in sequence to synchronously control the pulse laser to emit laser pulses, the electrically controlled rotating table and piezoelectric displacement table of the linear confocal scanning photoacoustic probe module, and control the motion range and speed of the probe scanning.

[0019] The imaging method of the fast linear confocal scanning photoacoustic microscopy imaging system comprises the following steps:

[0020] (1) Light source excitation: The sample to be tested is placed in a water tank; the laser emission module excites the laser, which irradiates the sample surface through a series of light paths to generate a photoacoustic signal;

[0021] (2) Sample scanning: In the linear confocal scanning photoacoustic probe module, the piezoelectric displacement stage is controlled to make the optical fiber resonate, and a fast, equidistant scanning is performed on a certain axis plane. Then, the electrically controlled rotary stage is adjusted at small angles, and the above scanning is repeated on the next axis plane. The area of ​​the optical fiber resonance scanning is always within the acoustic focusing area of ​​the hollow line focusing transducer. The full scanning of the sample surface can be completed after the electrically controlled rotary stage rotates 180°.

[0022] (3) Data acquisition: The photoacoustic signal generated by the sample is received by the hollow wire focusing transducer and converted into an electrical signal and transmitted to the system control and signal processing module, and then stored in the computer after amplification and filtering;

[0023] (4) Image reconstruction: The computer uses the GPU to quickly process and reconstruct the collected and stored data to achieve the purpose of real-time imaging.

[0024] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0025] 1. The present invention proposes a fast linear confocal scanning photoacoustic microscopy imaging system and an imaging method thereof, which utilizes the linear confocal principle to linearly scan samples and receive signals. Compared with the single-point focusing grating scanning method of traditional photoacoustic microscopy, the present invention can significantly improve the imaging speed.

[0026] 2. The present invention designs the coordinated movement of the electrically controlled rotating table and the piezoelectric displacement table to respectively control the scanning of the probe and the light beam on the sample surface, and uses the hollow wire focusing transducer to always keep the laser area of ​​the optical fiber resonance scanning within the acoustic focusing area, thereby reducing the tedious steps of frequent adjustment of the photoacoustic confocal and further improving the imaging efficiency.

[0027] 3. The present invention utilizes a piezoelectric displacement stage to drive the optical fiber at high frequency, so that the optical fiber can generate resonant swings and achieve large-scale and rapid scanning of the optical fiber, thereby further improving the imaging speed.

[0028] 4. The present invention utilizes photoacoustic confocal to ensure a high signal-to-noise ratio and high sensitivity of the imaging system. At the same time, the larger acoustic numerical aperture and short focal length design of the transducer also improve the imaging sensitivity and enhance biological safety.

[0029] 5. The photoacoustic microscopy imaging device provided by the present invention has a simple and compact structure, a small size, and flexible operation, and can further promote and optimize the miniaturization of photoacoustic imaging equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 is a schematic structural diagram of the photoacoustic microscopy imaging system of the present invention;

[0031] Figure 2 It is a schematic diagram of the principle of fast linear confocal scanning used in the present invention;

[0032] Figure 3 is a flow chart of an imaging method provided by an embodiment of the present invention;

[0033] Among them, 1-laser emission module: 11-pulse laser; 12-neutral density filter; 13-fiber coupler; 14-optical fiber; 2-linear confocal scanning photoacoustic probe module: 21-fiber collimator; 22-electrically controlled rotating table; 23-piezoelectric displacement table; 24-objective lens group; 25-hollow line focusing transducer; 26-probe housing; 27-water tank; 3-system control and signal processing module: 31-amplifier; 32-low-pass filter; 33-field programmable gate array; 34-computer. DETAILED DESCRIPTION

[0034] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention will be further clearly and completely described in conjunction with the embodiments and drawings below. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0035] like Figure 1 As shown, a fast linear confocal scanning photoacoustic microscopy imaging system includes a laser emission module 1, a linear confocal scanning photoacoustic probe module 2 and a system control and signal processing module 3; the laser emission module 1 generates a light beam, which enters the linear confocal scanning photoacoustic probe module 2 through an optical fiber, wherein the piezoelectric displacement stage drives the optical fiber to resonate and swing at high frequency and cooperates with the electric control rotating stage to control the probe to rotate and scan the sample to be tested to generate a photoacoustic signal, and the acoustic signal is converted into an electrical signal by a transducer and transmitted to the system control and signal processing module 3 for signal processing and image reconstruction. At the same time, the system control and signal processing module 3 is responsible for the laser triggering in the laser emission module 1 and the motion range and speed of the piezoelectric displacement stage and the electric control rotating stage in the linear confocal scanning photoacoustic probe module 2.

[0036] The laser emission module 1 includes a pulse laser 11, a neutral density filter 12, a fiber coupler 13 and an optical fiber 14; one end of the optical fiber 14 is connected to the fiber coupler 13, and the other end is connected to the fiber collimator 21 of the linear confocal scanning photoacoustic probe module 2, and is installed and fixed through the FC / PC interface.

[0037] The light beam generated by the pulse laser 11 enters the fiber coupler 13 through the neutral density filter 12 , and then enters the linear confocal scanning photoacoustic probe module 2 through the optical fiber 14 .

[0038] In this embodiment, the laser wavelength, duration and repetition frequency of the pulse laser 11 can be freely selected according to the sample to be tested and the purpose to be tested. The central wavelength of the neutral density filter 12 is adjusted according to the laser.

[0039] The linear confocal scanning photoacoustic probe module 2 includes a fiber collimator 21, an electrically controlled rotating stage 22, a piezoelectric displacement stage 23, an objective lens group 24, a hollow line focusing transducer 25, a probe housing 26 and a water tank 27; after the laser emitted from the fiber collimator 21 is focused by the objective lens group 24, it is irradiated on the sample to be tested through the hollow line focusing transducer 25, so that it generates a photoacoustic signal.

[0040] As a specific embodiment, the electrically controlled rotating table 22 is precisely processed by worm gear transmission, and can rotate the photoacoustic probe in a full circle without limit and at a small angle; the piezoelectric displacement table 23 mainly includes a piezoelectric driver, a friction rod and a slider. The piezoelectric driver is composed of a piezoelectric material (such as PZT, i.e., lead zinc titanate), which will deform under the action of an electric field. The piezoelectric driver is connected to one end of the friction rod; the friction rod is usually made of hard ceramic or metal, and is an intermediate component connecting the piezoelectric driver and the slider. The other end of the friction rod is connected to the slider; the slider is connected to the optical fiber 14. Open-loop control is adopted. When the piezoelectric driver produces displacement, the slider moves along the length direction of the friction rod, and the optical fiber 14 can be driven at high frequency to achieve resonant swing. The electrically controlled rotating table 22 and the piezoelectric displacement table 23 are respectively connected and fixed to the top of the photoacoustic probe housing 26 through a threaded structure, and the bottom of the photoacoustic probe housing 26 is located in a water tank 27. The electrically controlled rotating table 22 uses the probe as the rotation axis, and the center is a through hole. The piezoelectric displacement stage 23 is connected to the optical fiber 14, and the high frequency drives the optical fiber 14 to produce resonance, causing it to swing rapidly and evenly on a certain axis. The electrically controlled rotating stage 22 rotates to the next axis at a small angle to repeat the above scanning. The two move together to adjust the scanning area to achieve full scanning of the sample surface.

[0041] The hollow line focusing transducer 25 includes a transducer housing, a matching layer, a piezoelectric material, a backing layer and a signal line. The transducer housing is the external structure of the entire hollow line focusing transducer 25, and aluminum and other metals can be used to reduce the influence of the surrounding magnetic field and protect the structure; the inside of the transducer housing is a matching layer, a piezoelectric material, and a backing layer in sequence, wherein the matching layer is closely attached to the outer surface of the piezoelectric material to compensate for the acoustic impedance mismatch; the piezoelectric material is located between the matching layer and the backing layer, and can be made of piezoelectric materials such as PVDF, i.e. polyvinylidene fluoride, or LiNbO3, i.e. lithium niobate crystal; the backing layer is a hollow cylindrical backing layer, which supports the piezoelectric material and is coaxially arranged in the transducer housing, which can reflect part of the acoustic signal to the piezoelectric material for reception to improve the acoustic signal reception efficiency. The signal line is connected to the piezoelectric material, and is led out from the transducer housing and connected to the external signal processing module.

[0042] The piezoelectric material, center frequency, bandwidth and other parameters of the transducer are selected according to the sample to be tested and the purpose of the test; the light beam is focused on the sample after passing through a series of optical paths to generate a photoacoustic signal, which is received by the transducer and converted into an electrical signal and transmitted to the system control and signal processing module 3.

[0043] The system control and signal processing module 3 includes: an amplifier 31, a low-pass filter 32, a field programmable gate array 33 and a computer 34; the received electrical signal is amplified by the amplifier 31 and filtered by the low-pass filter 32, and then transmitted to the computer 34 for data acquisition, signal processing and image reconstruction. At the same time, the computer 34 is used to synchronously control the laser excitation of the pulse laser 11 and the motion range and speed of the electric control rotating stage 22 and the piezoelectric displacement stage 23 through the field programmable gate array 33.

[0044] In this embodiment, the sample to be tested is placed in the water tank 27 and attached to the surface of the photoacoustic probe. The computer 34 controls the pulse laser 11 to excite the laser with a wavelength of 532nm, the repetition frequency can reach up to 1.5MHz, and the average power can reach up to 30W. The neutral density filter 12 has a central wavelength of 560nm and a bandwidth of 10nm. The emitted laser passes through the neutral density filter 12 for light intensity attenuation adjustment, enters the fiber coupler 13 and the optical fiber 14, and then enters the linear confocal scanning photoacoustic probe module 2.

[0045] In this embodiment, the laser generated by the laser emitting module 1 is emitted from the optical fiber collimator 21, focused by the objective lens group 24, and passed through the hollow line focusing transducer 25, and irradiated on the surface of the sample to be tested, so that it generates a photoacoustic signal. Specifically, Figure 2 As shown, the computer 34 controls the piezoelectric displacement stage 23 to drive the optical fiber 14 at high frequency to produce resonant oscillation, and performs fast, equidistant scanning on a certain axis plane, and then adjusts the electric-controlled rotating stage 22 at small angles, switches to the next axis plane and repeats the above scanning. The area of ​​the optical fiber resonance scanning is always located within the transducer acoustic focusing area, realizing photoacoustic linear confocalization. The electric-controlled rotating stage 22 can complete the full scan of the sample surface after rotating 180°.

[0046] In this embodiment, the hollow line focusing transducer 25 also includes a pair of symmetrically arranged high-frequency piezoelectric elements, which can be set according to the scanning length, width and curvature, and are pasted on the concave surface of the bottom of the hollow cylindrical backing layer through epoxy resin. The center frequency of the hollow line focusing transducer 25 is 50MHz and the bandwidth is 78%. The hollow line focusing transducer 25 receives the photoacoustic signal and converts it into an electrical signal and transmits it to the system control and signal processing module 3. The signal is amplified by the amplifier 31 and filtered by the low-pass filter 32 and then transmitted to the computer 34.

[0047] As a specific embodiment, in the system control and signal processing module 3, the amplifier 31 amplifies the signal by 48 dB; the cutoff frequency of the low-pass filter 32 is 70 MHz; the field programmable gate array 33 and the computer 34 collect and process the signal data at a frequency of 200 MHz, with a sampling accuracy of 14 bits, and then use the GPU to reconstruct the image.

[0048] In this embodiment, if Figure 3 As shown, the imaging method using the fast linear confocal scanning photoacoustic microscopy imaging system comprises the following steps:

[0049] (1) Light source excitation: The sample to be tested is placed in the water tank 27; the laser emission module 1 excites the laser, which is irradiated to the sample surface through a series of light paths to generate a photoacoustic signal.

[0050] (2) Sample scanning: In the linear confocal scanning photoacoustic probe module 2, the piezoelectric displacement stage 23 is controlled to make the optical fiber resonate, and a fast, equidistant scanning is performed on a certain axis plane. Then, the electrically controlled rotary stage is adjusted at small angles, and the above scanning is repeated on the next axis plane. The area of ​​the optical fiber resonance scanning is always located within the transducer acoustic focusing area. The full scan of the sample surface can be completed after the electrically controlled rotary stage rotates 180°.

[0051] (3) Data acquisition: The photoacoustic signal generated by the sample is received by the transducer and converted into an electrical signal and transmitted to the system control and signal processing module 3, and then stored in the computer after amplification and filtering.

[0052] (4) Image reconstruction: The computer 34 uses the GPU to quickly process and reconstruct the collected and stored data to achieve the purpose of real-time imaging.

[0053] Finally, it should be noted that the above embodiments are only embodiments adopted for facilitating the understanding of the present invention, and are not intended to limit the present invention. Those skilled in the art should understand that any modifications and changes can be made in the form and details of the implementation without departing from the spirit and scope disclosed by the present invention, but the scope of patent protection of the present invention shall still be subject to the scope defined by the attached claims.

Claims

1. A fast linear confocal scanning photoacoustic microscopy imaging system, characterized in that: The invention comprises a laser emission module (1), a linear confocal scanning photoacoustic probe module (2) and a system control and signal processing module (3); the laser emission module (1) generates a light beam, which is emitted through an optical fiber (14) and enters the linear confocal scanning photoacoustic probe module (2); the linear confocal scanning photoacoustic probe module (2) controls the probe to rotate and quickly scans the sample to be tested to generate a photoacoustic signal, and converts the acoustic signal into an electrical signal, which is transmitted to the system control and signal processing module (3) for data processing and image reconstruction.

2. A fast linear confocal scanning photoacoustic microscopy imaging system according to claim 1, characterized in that: The laser emission module (1) comprises a pulse laser (11), a neutral density filter (12), a fiber coupler (13) and an optical fiber (14); the light beam generated by the pulse laser (11) passes through the neutral density filter (12) and enters the fiber coupler (13), and then enters the linear confocal scanning photoacoustic probe module (2) through the optical fiber (14).

3. A fast linear confocal scanning photoacoustic microscopy imaging system according to claim 1, characterized in that: The linear confocal scanning photoacoustic probe module (2) comprises a fiber collimator (21), an electrically controlled rotating stage (22), a piezoelectric displacement stage (23), an objective lens group (24), a hollow line focusing transducer (25), a probe housing (26) and a water tank (27); The piezoelectric displacement stage (23) controls the resonant oscillation of the optical fiber (14), and cooperates with the electrically controlled rotating stage (22) to control the rotation of the probe, quickly scanning the sample to be tested to generate a photoacoustic signal. At the same time, the system control and signal processing module (3) triggers the laser in the laser emission module (1), and controls the movement of the piezoelectric displacement stage (23) and the electrically controlled rotating stage (22); The optical fiber collimator (21) is arranged at the end of the optical fiber (14). After the laser emitted by the optical fiber collimator (21) is focused by the objective lens group (24), it is irradiated on the sample to be tested placed in the water tank (27) through the hollow line focusing transducer (25), so that it generates a photoacoustic signal.

4. A fast linear confocal scanning photoacoustic microscopy imaging system according to claim 3, characterized in that: The probe housing (26) is fixed to the hollow electrically controlled rotating platform (22), the piezoelectric displacement platform (23) is fixed in the probe housing (26), and the probe housing (26), the electrically controlled rotating platform (22) and the piezoelectric displacement platform (23) are assembled into one body through a threaded structure; The electrically controlled rotating table (22) uses the probe as a rotating axis and has a through hole at its center; the piezoelectric displacement table (23) drives the optical fiber (14) at high frequency to generate resonance, so that the optical fiber (14) swings rapidly and evenly on a certain axial plane; the electrically controlled rotating table (22) rotates to the next axial plane to repeat scanning; the electrically controlled rotating table (22) and the piezoelectric displacement table (23) move in coordination to adjust the scanning area and realize full scanning of the sample surface.

5. A fast linear confocal scanning photoacoustic microscopy imaging system according to claim 4, characterized in that: The piezoelectric displacement stage (23) comprises a piezoelectric driver, a friction rod and a slider, the two ends of the friction rod are respectively connected to the piezoelectric driver and the slider, and the slider is connected to the optical fiber (14).

6. A fast linear confocal scanning photoacoustic microscopy imaging system according to claim 3, characterized in that: The hollow line focusing transducer (25) comprises a hollow cylindrical backing layer and a pair of symmetrically arranged high-frequency piezoelectric elements, wherein the high-frequency piezoelectric elements are attached to the concave surface at the bottom of the hollow cylindrical backing layer.

7. The fast linear confocal scanning photoacoustic microscopy imaging system according to claim 5, characterized in that: The laser area of ​​the resonant scanning of the optical fiber (14) is always located within the acoustic focusing area of ​​the hollow line focusing transducer (25), and the hollow line focusing transducer (25) converts the photoacoustic signal into an electrical signal and transmits it to the system control and signal processing module (3).

8. The fast linear confocal scanning photoacoustic microscopy imaging system according to claim 1, characterized in that: The system control and signal processing module (3) comprises an amplifier (31), a low-pass filter (32), a field programmable gate array (33) and a computer (34); the electrical signal converted by the hollow line focusing transducer (25) of the linear confocal scanning photoacoustic probe module (2) is amplified by the amplifier (31), then filtered by the low-pass filter (32) and transmitted to the computer (34) for photoacoustic signal processing and image reconstruction.

9. A fast linear confocal scanning photoacoustic microscopy imaging system according to claim 8, characterized in that: The field programmable gate array (33), the computer (34), and the pulse laser (11) of the laser emission module (1) are connected in sequence and are used to synchronously control the pulse laser (11) to emit laser pulses, the electrically controlled rotating table (22) and the piezoelectric displacement table (23) of the linear confocal scanning photoacoustic probe module (2), and to control the motion range and speed of the probe scanning.

10. An imaging method for a fast linear confocal scanning photoacoustic microscopy imaging system according to any one of claims 1 to 9, characterized in that: The steps include: (1) Light source excitation: placing the sample to be tested in a water tank (27); the laser emission module (1) excites the laser, which is irradiated onto the sample surface through a series of light paths to generate a photoacoustic signal; (2) Sample scanning: In the linear confocal scanning photoacoustic probe module (2), the piezoelectric displacement stage (23) is controlled to make the optical fiber resonate, and a fast, equidistant scanning is performed on a certain axis plane, and then the electric control rotating stage (22) is adjusted at a small angle, and the above scanning is repeated on the next axis plane. The area of ​​the optical fiber resonance scanning is always located within the acoustic focusing area of ​​the hollow line focusing transducer (25). After the electric control rotating stage rotates 180°, the entire surface of the sample can be scanned; (3) Data acquisition: The photoacoustic signal generated by the sample is received by the hollow wire focusing transducer (25) and converted into an electrical signal and transmitted to the system control and signal processing module (3), and then stored in the computer after amplification and filtering; (4) Image reconstruction: The computer (34) uses the GPU to quickly process and reconstruct the collected and stored data to achieve the purpose of real-time imaging.

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