A fast linear confocal scanning photoacoustic microscopy imaging system and imaging method thereof

Abstract

The present invention discloses a fast linear confocal scanning photoacoustic microscopy imaging system and its imaging method. The imaging system includes a laser emission module, a linear confocal scanning photoacoustic probe module, and a system control and signal processing module. By controlling a piezoelectric displacement stage to resonate an optical fiber, the emitted laser beam is rapidly scanned across the sample in a linear, uniform step. The electrically controlled rotating stage is controlled to repeat this scanning at small angles, rotating to 180° to complete a full scan of the sample surface. After the sample absorbs the laser beam, an acoustic signal is generated, which is received and converted into an electrical signal by a hollow line focusing transducer and transmitted to a computer for signal processing and image reconstruction. The present invention utilizes the principle of linear confocal scanning to achieve fast and stable scanning of the sample, while optimizing probe miniaturization and ensuring imaging sensitivity.

Description

Technical Field

[0001] The present 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 novel biomedical imaging technique that combines the high contrast of optical imaging with the deep penetration of ultrasound imaging. When biological tissue absorbs laser energy, it generates ultrasound waves due to thermoelastic expansion. These waves are then detected by an ultrasound transducer and converted into electrical signals. Through signal processing and image reconstruction algorithms, images are formed that reflect the internal structure and function of the tissue. The superior spatial resolution and deep imaging depth of photoacoustic imaging hold great promise for biomedical imaging.

[0003] Despite the significant advantages of photoacoustic imaging, existing technologies still face challenges and limitations in practical applications. For example, to ensure resolution, traditional photoacoustic microscopy typically uses single-point focused raster scanning, using various mechanical or optical scanning methods to achieve comprehensive imaging of the sample. However, this single-point focused scanning method is time-consuming and difficult to meet the needs of dynamic monitoring of biological processes. In addition, using a large spot to illuminate the sample can increase scanning speed, but the imaging resolution is low and is limited by the size of the transducer array, which is not conducive to system miniaturization and cost savings.

[0004] An existing waterless coupling fast linear confocal scanning photoacoustic probe and imaging method thereof (CN108742528A) utilizes a galvanometer to achieve fast linear scanning of a laser within the acoustic field focal area of ​​an ultrasonic transducer, and utilizes waterless coupling materials to reduce the complexity of the imaging operation. However, the disadvantage is that the acoustic field space must accommodate other components, resulting in a certain amount of acoustic signal loss, and the sensitivity is limited by the acoustic reception efficiency and acoustic numerical aperture. A new scanning method and device for an optical resolution photoacoustic microscope (CN106769876A) utilizes a linear confocal signal generation and collection method to improve the imaging signal-to-noise ratio and sensitivity, ensuring image quality. However, the laser scanning and acoustic signal reception are driven by two controller systems, requiring the laser scanning area of ​​the two-dimensional scanning galvanometer and the acoustic focal area of ​​the ultrasonic transducer to be adjusted separately to ensure their overlap, 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 existing technology and provide a fast linear confocal scanning photoacoustic microscopy imaging system and imaging method. By controlling the coordinated movement of a piezoelectric translation stage and an electrically controlled rotation stage, and utilizing the linear confocal principle, a light beam is linearly scanned across a sample to be tested to generate a photoacoustic signal, which is received by a hollow line focusing transducer and reconstructed by computer processing. This achieves fast scanning imaging, ensures high imaging sensitivity and a high signal-to-noise ratio, and further improves 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 includes 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 the sample to be tested to generate a photoacoustic signal, and converts the acoustic signal into an electrical signal. The electrical signal 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 into the fiber coupler, and then enters the linear confocal scanning photoacoustic probe module through the optical fiber.

[0009] Furthermore, 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 rotary 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 control and signal processing module triggers the laser in the laser emission module, and controls the movement of the piezoelectric displacement stage and the electrically controlled rotary stage.

[0011] The fiber collimator is set at the end of the optical fiber. After the laser emitted by the 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 platform, the piezoelectric displacement platform is fixed in the probe housing, and the probe housing, the electrically controlled rotating platform, and the piezoelectric displacement platform are assembled into one through a threaded structure;

[0013] The electrically controlled rotary stage uses the probe as the rotation axis and has a through hole in the center. The piezoelectric displacement stage drives the optical fiber at high frequency to generate resonance, causing the optical fiber to swing rapidly and evenly on a certain axis. The electrically controlled rotary stage rotates to the next axis to repeat the scan. The electrically controlled rotary 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 includes 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 includes 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 of 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, 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 rotation stage and piezoelectric displacement stage 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 includes 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, equal-step scanning is performed on a certain axis. Then, the electric-controlled rotary stage is adjusted at small angles, and the above scanning is repeated on the next axis. The area of ​​the optical fiber resonance scanning is always within the acoustic focusing area of ​​the hollow line focusing transducer. The full scan of the sample surface is completed after the electric-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 imaging method thereof, which utilizes the linear confocal principle to linearly scan samples and receive signals. Compared with the single-point focusing raster 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 an electrically controlled rotary stage and a piezoelectric displacement stage to control the scanning of the probe and light beam on the sample surface respectively. Utilizing a hollow wire focusing transducer, the laser area of ​​the fiber resonance scanning is always kept within the acoustic focusing region, thus reducing the tedious steps of frequent photoacoustic confocal adjustments and further improving imaging efficiency.

[0027] 3. The present invention utilizes a piezoelectric displacement stage to drive the optical fiber at high frequency, causing the optical fiber to generate resonant oscillations, thereby enabling 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 imaging sensitivity and enhance biological safety.

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

[0030] Figure 1 Schematic diagram of the structure of the photoacoustic microscopy system of the present invention;

[0031] Figure 2 This is a schematic diagram of the principle of rapid 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-pulsed laser; 12-neutral density filter; 13-fiber coupler; 14-optical fiber; 2-linear confocal scanning photoacoustic probe module: 21-fiber collimator; 22-electrically controlled rotation stage; 23-piezoelectric displacement stage; 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] To make the purpose, technical solutions and advantages of the present invention clearer, the present invention will be further clearly and completely described below in conjunction with the embodiments and drawings. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts 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. A piezoelectric displacement stage drives the optical fiber to resonate and oscillate at high frequency, and cooperates with an electrically controlled rotary stage to control the probe's rotation and scanning of the sample to be measured to generate a photoacoustic signal. 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. The system control and signal processing module 3 is also responsible for triggering the laser in the laser emission module 1 and the range and speed of motion of the piezoelectric displacement stage and electrically controlled rotary stage in the linear confocal scanning photoacoustic probe module 2.

[0036] The laser emission module 1 includes a pulsed 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 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 .

[0038] In this embodiment, the wavelength, duration, and repetition frequency of the pulsed laser 11 can be freely selected according to the sample to be tested and the purpose of the test. The center 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 rotary 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 laser emitted by the fiber collimator 21 is focused by the objective lens group 24, and then irradiated onto the sample to be tested through the hollow line focusing transducer 25, causing it to generate a photoacoustic signal.

[0040] As a specific embodiment, the electrically controlled rotary stage 22 is precision-machined using a worm gear drive, enabling full-circle, infinitely narrow angle rotation of the photoacoustic probe. The piezoelectric displacement stage 23 primarily comprises a piezoelectric driver, a friction rod, and a slider. The piezoelectric driver is constructed from a piezoelectric material (such as PZT, or lead-zinc titanate) that deforms under the influence of an electric field. The piezoelectric driver is connected to one end of the friction rod. The friction rod, typically made of hard ceramic or metal, serves as an intermediate component connecting the piezoelectric driver and the slider, with its other end connected to the slider. The slider is connected to the optical fiber 14. Open-loop control is employed. When the piezoelectric driver is displaced, the slider moves along the length of the friction rod, driving the optical fiber 14 at high frequency to achieve resonant oscillation. The electrically controlled rotary stage 22 and the piezoelectric displacement stage 23 are respectively secured to the top of the photoacoustic probe housing 26 via threaded connections. The bottom of the photoacoustic probe housing 26 is located within a water tank 27. The electrically controlled rotary stage 22 rotates around the probe and has a through-hole at its center. The piezoelectric displacement stage 23 is connected to the optical fiber 14, and the high-frequency driving optical fiber 14 produces resonance, causing it to swing rapidly and evenly on a certain axis. The electrically controlled rotary stage 22 rotates to the next axis at a small angle and repeats the above scanning. The two move together to adjust the scanning area to achieve a full scan 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 can be made of metals such as aluminum to reduce the impact of the surrounding magnetic field and protect the structure. Inside the transducer housing are the matching layer, piezoelectric material, and backing layer, respectively. The matching layer is tightly 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 that supports the piezoelectric material and is coaxially arranged in the transducer housing. It can reflect part of the acoustic signal to the piezoelectric material for reception, thereby improving the efficiency of acoustic signal reception. The signal line is connected to the piezoelectric material and is led out of the transducer housing to connect 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. Received electrical signals are amplified by the amplifier 31 and filtered by the low-pass filter 32 before being transmitted to the computer 34 for data acquisition, signal processing, and image reconstruction. Furthermore, the computer 34, through the field-programmable gate array 33, synchronously controls the laser excitation of the pulsed laser 11 and the range and speed of motion of the electrically controlled rotary stage 22 and the piezoelectric translation stage 23.

[0044] In this embodiment, the sample to be tested is placed in a water tank 27 and attached to the surface of the photoacoustic probe. Computer 34 controls pulsed laser 11 to emit laser light with a wavelength of 532 nm, a repetition rate of up to 1.5 MHz, and an average power of up to 30 W. Neutral density filter 12 has a central wavelength of 560 nm and a bandwidth of 10 nm. The emitted laser light passes through neutral density filter 12 for intensity attenuation adjustment, enters fiber coupler 13 and optical fiber 14, and then enters 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 generate resonant oscillation, performs rapid, equi-step scanning on a certain axial plane, and then adjusts the electric-controlled rotary stage 22 at small angles, switches to the next axial plane and repeats the above scanning. The area of ​​the optical fiber resonant scanning is always located within the acoustic focusing area of ​​the transducer, achieving photoacoustic linear confocalization. The electric-controlled rotary stage 22 can complete the full scan of the sample surface after rotating 180°.

[0046] In this embodiment, the hollow-wire focused transducer 25 also includes a pair of symmetrically arranged high-frequency piezoelectric elements. These elements can be configured to adjust the scanning length, width, and curvature. They are attached to the concave surface of the bottom of the hollow cylindrical backing layer using epoxy resin. The center frequency of the hollow-wire focused transducer 25 is 50 MHz, and its bandwidth is 78%. The hollow-wire focused transducer 25 receives the photoacoustic signal and converts it into an electrical signal, which is transmitted to the system control and signal processing module 3. The signal is amplified by an amplifier 31 and filtered by a low-pass filter 32 before being transmitted to a 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 is as follows:

[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, equal-step scanning is performed on a certain axial plane. Then, the electric-controlled rotary stage is adjusted at small angles, and the above scanning is repeated on the next axial plane. The area of ​​the optical fiber resonance scanning is always within the transducer acoustic focusing area. After the electric-controlled rotary stage rotates 180°, the entire sample surface can be scanned.

[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 embodiments described above are merely intended to facilitate 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 variations in the form and details of the embodiments may be made without departing from the spirit and scope of the present invention. However, the scope of patent protection of the present invention shall remain subject to the scope defined by the appended 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 scan 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; The laser emission module (1) comprises a pulse laser (11), a neutral density filter (12), a fiber coupler (13) and an optical fiber (14); a light beam generated by the pulse laser (11) passes through the neutral density filter (12) and enters the optical fiber coupler (13), and then enters the linear confocal scanning photoacoustic probe module (2) through the optical fiber (14); 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); The piezoelectric displacement stage (23) controls the resonant oscillation of the optical fiber (14) and cooperates with the electrically controlled rotary 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) controls the laser triggering in the laser emission module (1) and controls the movement of the piezoelectric displacement stage (23) and the electrically controlled rotary stage (22); The optical fiber collimator (21) is provided at the end of the optical fiber (14). After the laser light 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 the sample generates a photoacoustic signal. The probe housing (26) is fixed to the hollow electrically controlled rotating table (22), the piezoelectric displacement table (23) is fixed in the probe housing (26), and the probe housing (26), the electrically controlled rotating table (22), and the piezoelectric displacement table (23) are assembled into one body via a threaded structure; The electrically controlled rotating stage (22) uses the probe as a rotating axis and has a through hole at its center; the piezoelectric displacement stage (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 axis plane, and the electrically controlled rotating stage (22) rotates to the next axis plane to repeat the scanning, and the electrically controlled rotating stage (22) and the piezoelectric displacement stage (23) cooperate to adjust the scanning area to achieve full scanning of the sample surface; 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 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), filtered by the low-pass filter (32), and then transmitted to the computer (34) for photoacoustic signal processing and image reconstruction.

2. A fast linear confocal scanning photoacoustic microscopy system according to claim 1, 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).

3. The fast linear confocal scanning photoacoustic microscopy imaging system according to claim 1, 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.

4. The fast linear confocal scanning photoacoustic microscopy imaging system according to claim 2, characterized in that: The laser area of ​​the optical fiber (14) resonant scanning 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).

5. The fast linear confocal scanning photoacoustic microscopy imaging system according to claim 1, 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 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.

6. A method for implementing the fast linear confocal scanning photoacoustic microscopy imaging system according to any one of claims 1 to 5, characterized in that: The steps include: (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 onto the sample surface 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, equal-step scanning is performed on a certain axis. Then, the electric-controlled rotary stage (22) is adjusted at small angles, and the above scanning is repeated on the next axis. 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-controlled rotary stage rotates 180°, the entire sample surface 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, which is transmitted to the system control and signal processing module (3), amplified and filtered, and then stored in the computer; (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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