Optoacoustic enhanced imaging system and imaging method based on speckle variance

Abstract

The application discloses a kind of based on speckle variance's photoacoustic enhancement imaging system and imaging method, imaging system includes laser, modulation component, beam expander component, optical galvanometer, objective, container, ultrasonic transducer, galvanometer controller, data acquisition card and imaging processing terminal.Compared with prior art, the application utilizes the dynamic change characteristic of the amplitude and position of photoacoustic signal emitted by flowing red blood cells with time, adopts optical scanning mode to carry out fast, multiple scanning at the same site to obtain multiple ultrasonic signals at the same site, the ultrasonic signals of multiple sites obtained by scanning are processed by speckle variance extraction algorithm, photoacoustic blood vessel enhancement image based on speckle variance method can be obtained, imaging efficiency is greatly improved, and non-invasive, non-marking, specific, high-contrast, high-resolution imaging of melanoma and nourishing blood vessels can be realized.

Description

Technical Field

[0001] This invention relates to the field of microscopic imaging technology, and more particularly to a photoacoustic enhancement imaging system and method based on speckle variance. Background Technology

[0002] Melanoma, which develops from melanocytes, is the least common but most deadly form of skin cancer. Its incidence has increased significantly over the past 20 years. Melanoma staging determines clinical decisions, and mortality increases with tumor stage. Unlike benign lesions, malignant melanoma alters local skin microvessels, exhibiting a higher vascular density. Therefore, non-invasive observation of the microvascular morphology of suspected malignant melanoma lesions can serve as an important basis for melanoma diagnosis. Histological studies report that vascular changes caused by malignant melanoma can extend throughout the entire depth of the skin. As melanoma thickness increases, its internal blood vessels become more disordered and heterogeneous. Clearly, observing vascular morphology is crucial for a deeper understanding and accurate diagnosis of melanoma.

[0003] Clinical diagnosis of melanoma relies primarily on histopathological examination. In histological sections, blood vessels collapse after excision, fixation, and staining, and histology only provides two-dimensional sections, offering little knowledge of the three-dimensional vascular network within the tumor. It is well known that tumor structure influences areas of angiogenesis. Non-invasive, in vivo methods providing three-dimensional microvascular mapping within melanoma offer the possibility of preoperative risk assessment for malignant melanoma. Current non-invasive imaging methods cannot fully resolve microvessels across the entire depth of the skin, hindering the full development of tumor vascular features as biomarkers for melanoma detection.

[0004] Therefore, existing techniques for vascular tissue imaging suffer from poor depth resolution accuracy. Summary of the Invention

[0005] This invention provides a photoacoustic enhancement imaging system and method based on speckle variance, aiming to solve the problem of poor depth resolution accuracy in traditional pathological section imaging techniques used for vascular tissue imaging.

[0006] In a first aspect, embodiments of the present invention provide a photoacoustic enhancement imaging system based on speckle variance, wherein the system includes a laser, a modulation component, a beam expander component, an optical galvanometer, an objective lens, a container, an ultrasonic transducer, a galvanometer controller, a data acquisition card, and an imaging processing terminal.

[0007] The laser is positioned upstream of the beam expander assembly, and the modulation assembly is positioned between the laser and the beam expander assembly; the optical galvanometer is positioned downstream of the beam expander assembly; and the objective lens is positioned downstream of the optical galvanometer.

[0008] The ultrasonic transducer is disposed inside the container, which contains a coupling solution, and the sample is placed inside the container; the objective lens is disposed above the container, and the ultrasonic transducer is disposed to the side of the sample.

[0009] The optical galvanometer is connected to the galvanometer controller, the ultrasonic transducer is connected to the data acquisition card, and the imaging processing terminal is connected to both the galvanometer controller and the data acquisition card.

[0010] The laser generated by the laser is transmitted through the modulation component into the optical galvanometer; the galvanometer controller sends a galvanometer control signal to control the optical galvanometer to perform a scanning operation to generate a scanning beam; the scanning beam is transmitted into the objective lens and focused; the focused beam emitted from the objective lens illuminates the sample;

[0011] The data acquisition card acquires the ultrasonic signals detected by the ultrasonic transducer and outputs them to the imaging processing terminal; the imaging processing terminal processes the ultrasonic signals from multiple sites obtained by scanning using a speckle variance extraction algorithm to generate sample images.

[0012] In the speckle variance-based photoacoustic enhancement imaging system, the sample is placed at the focal point of the beam emitted from the objective lens.

[0013] The photoacoustic enhancement imaging system based on speckle variance, wherein the laser is a green laser.

[0014] The photoacoustic enhancement imaging system based on speckle variance includes a modulation component comprising a polarizer and a half-wave plate; the polarizer is disposed upstream of the half-wave plate.

[0015] The photoacoustic enhancement imaging system based on speckle variance, wherein the beam expander component includes a first focusing lens and a second focusing lens.

[0016] The photoacoustic enhancement imaging system based on speckle variance, wherein the ultrasonic transducer is a needle-shaped ultrasonic transducer.

[0017] In the speckle variance-based photoacoustic enhancement imaging system, the coupling solution is deionized water.

[0018] Secondly, embodiments of this application also provide a photoacoustic enhancement imaging method based on speckle variance, wherein the imaging method is applied to the imaging system described in the first aspect above, and the imaging method includes:

[0019] The laser is turned on to emit a laser beam, which is modulated by the modulation component and expanded by the beam expander component before entering the optical galvanometer.

[0020] The optical galvanometer performs a scanning operation according to the received galvanometer control signal to generate a scanning beam and inject it into the objective lens. The objective lens focuses the scanning beam and illuminates the sample and scans the sample. The sample is excited by the scanning beam to generate ultrasonic waves, which are then transmitted to the ultrasonic detector through the coupling solution.

[0021] The data acquisition card acquires the ultrasonic signals detected by the ultrasonic transducer and transmits them to the imaging processing terminal in real time.

[0022] The imaging processing terminal uses a speckle variance extraction algorithm to process the ultrasonic signals from multiple sites obtained by scanning to generate sample images. Each point corresponds to a preset number of scans.

[0023] The photoacoustic enhancement imaging method based on speckle variance, wherein the formula corresponding to the speckle variance extraction algorithm is:

[0024] Among them, A v,m S is the photoacoustic signal obtained from the m-th scan of the v-th site in the sample, where M is the preset number of scans, which ranges from 4 to 8. v,m The speckle variance value is calculated based on the ultrasonic signals from multiple scans of the v-th site in the sample.

[0025] This invention provides a photoacoustic enhancement imaging system and method based on speckle variance. The imaging system includes a laser, a modulation component, a beam expander, an optical galvanometer, an objective lens, a container, an ultrasonic transducer, a galvanometer controller, a data acquisition card, and an imaging processing terminal. Compared with existing technologies, this invention utilizes the dynamic changes in amplitude and position of photoacoustic signals emitted by flowing red blood cells over time. It employs optical scanning to perform rapid, multiple scans at the same site to obtain multiple ultrasonic signals from the same location. By processing the ultrasonic signals from the multiple sites obtained through a speckle variance extraction algorithm, a photoacoustic vascular enhancement image based on speckle variance can be obtained, significantly improving imaging efficiency. This enables non-invasive, label-free, specific, high-contrast, and high-resolution imaging of melanoma and nutrient vessels. Attached Figure Description

[0026] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 This is a structural diagram of the photoacoustic enhancement imaging system based on speckle variance provided in an embodiment of the present invention.

[0028] Figure 2 This is a flowchart of the photoacoustic enhancement imaging method based on speckle variance provided in an embodiment of the present invention.

[0029] Figure 3 This is an application effect diagram of the photoacoustic enhancement imaging method based on speckle variance provided in the embodiments of the present invention;

[0030] Figure 4 This is another application effect diagram of the photoacoustic enhancement imaging method based on speckle variance provided in the embodiments of the present invention;

[0031] Figure 5 This is another application effect diagram of the photoacoustic enhancement imaging method based on speckle variance provided in the embodiments of the present invention.

[0032] Reference numerals: 1. Laser; 2. Modulation component; 3. Beam expander component; 4. Optical galvanometer; 5. Objective lens; 6. Container; 7. Ultrasonic transducer; 8. Galvanometer controller; 9. Data acquisition card; 10. Imaging processing terminal; 21. Polarizer; 22. Half-wave plate; 31. First focusing lens; 32. Second focusing lens; 101. First reflecting mirror; 102. Second reflecting mirror. Detailed Implementation

[0033] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0034] It should be understood that, when used in this specification and the appended claims, the terms "comprising" and "including" indicate the presence of the described features, integrals, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or collections thereof.

[0035] It should also be understood that the terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the invention. As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise.

[0036] It should also be further understood that the term "and / or" as used in this specification and the appended claims refers to any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0037] In this embodiment, please refer to Figure 1 As shown in the figure, this embodiment of the invention provides a photoacoustic enhancement imaging system based on speckle variance. The system includes a laser 1, a modulation component 2, a beam expander 3, an optical galvanometer 4, an objective lens 5, a container 6, an ultrasonic transducer 7, a galvanometer controller 8, a data acquisition card 9, and an imaging processing terminal 10. The laser 1 is positioned upstream of the beam expander 3, and the modulation component 2 is positioned between the laser 1 and the beam expander 3. The optical galvanometer 4 is positioned downstream of the beam expander 3. The objective lens 5 is positioned downstream of the optical galvanometer 4. The ultrasonic transducer 7 is positioned inside the container 6, which contains a coupling solution, and a sample is placed inside the container 6. The objective lens 5 is positioned above the container 6, and the ultrasonic transducer 7 is positioned to the side of the sample. The optical galvanometer 4 and the galvanometer controller 8 are connected. The ultrasonic transducer 7 is connected to the data acquisition card 9 via a communication connection with the controller 8. The imaging processing terminal 10 is connected to both the galvanometer controller 8 and the data acquisition card 9. The laser generated by the laser 1 is transmitted to the optical galvanometer 4 via the modulation component 2. The galvanometer controller 8 sends a galvanometer control signal to control the optical galvanometer 4 to perform a scanning operation to generate a scanning beam. The scanning beam is transmitted to the objective lens 5 and focused. The focused beam emitted from the objective lens 5 illuminates the sample. The data acquisition card 9 acquires the ultrasonic signals detected by the ultrasonic transducer 7 and outputs them to the imaging processing terminal 10. The imaging processing terminal 10 processes the ultrasonic signals obtained from multiple scanning points using a speckle variance extraction algorithm to generate a sample image, with each point corresponding to a preset number of scans.

[0038] Specifically, laser 1 is positioned upstream of the imaging optical path and serves as the excitation source. Modulation component 2 modulates the laser beam generated by the excitation light to change its polarization state. Beam expander component 3 expands the modulated beam to maximize the coverage of the optical mirror 4. The expanded excitation light is then incident on the optical mirror 4. Mirror controller 8 sends a mirror control signal to control the optical mirror 4 to perform a scanning operation, thereby generating a scanning beam. After scanning by the optical mirror 4, the excitation beam is focused by objective lens 5 and incident on the sample. The sample is placed on the bottom of container 6. Under the illumination of the incident light, due to the instantaneous thermoelastic effect, the sample generates ultrasonic waves. Ultrasonic transducer 7 detects the generated ultrasonic signals (the sample and ultrasonic transducer 7 are coupled using a coupling solution). The ultrasonic signals are acquired by data acquisition card 9 and sent to imaging processing terminal 10 (computer host). Imaging processing terminal 10 is used for subsequent data analysis and image reconstruction. When scanning is performed through the optical galvanometer 4, the imaging processing terminal 10 can transmit motion commands to the galvanometer controller 8. The galvanometer controller 8 outputs corresponding galvanometer control signals (different control voltages) according to the motion commands to control the optical galvanometer 4.

[0039] A first reflector 101 and a second reflector 102 are arranged between the beam expander 3 and the optical galvanometer 4. Both the first reflector 101 and the second reflector 102 can be used to reflect the beam. By combining the first reflector 101 and the second reflector 102, the beam can be reflected and the angle of the beam can be adjusted so that the beam can enter the optical galvanometer 4 more accurately.

[0040] In the imaging system described above, the same site of the sample can be scanned multiple times. Each scan by the irradiation beam can acquire a set of ultrasonic signals, so multiple scans can acquire multiple ultrasonic signals at the same site.

[0041] In a more specific embodiment, the sample is placed at the focal point of the beam emitted from the objective lens 5. Specifically, the laser 1 is a green laser 1.

[0042] Specifically, to achieve better imaging results, the sample is placed at the focal point of the beam emitted from objective lens 5. This setting enables the tissue sample to generate stronger ultrasound waves at the focal point of the irradiation beam, thereby increasing the concentration of the generated ultrasound waves and thus improving the signal strength of the ultrasound signal, thereby improving the imaging quality of the sample. Furthermore, to improve the quality of the ultrasound signal generated by the sample, laser 1 can be set to a green laser 1, which can generate near-green excitation light. In a more specific embodiment, laser 1 can be set to a 532nm short-pulse laser 1, which can generate a short-pulse laser beam with a wavelength of 532nm, thereby improving the effect of the laser beam in exciting the sample to generate ultrasound waves. The wavelength of the laser beam is not limited to 532nm; it can also be other wavelengths, depending on the peak wavelength of the irradiation beam suitable for exciting ultrasound waves from different substances in the sample.

[0043] In a more specific embodiment, the modulation component 2 includes a polarizer 21 and a half-wave plate 22; the polarizer 21 is disposed upstream of the half-wave plate 22. The beam expander component 3 includes a first focusing lens 31 and a second focusing lens 32.

[0044] To improve the modulation effect of modulation component 2, modulation component 2 can be configured to consist of polarizer 21 and half-wave plate 22. The combination of polarizer 21 and half-wave plate 22 modulates the incident excitation light, which can effectively change the polarization state of the beam, thereby improving the beam modulation effect. Beam expander component 3 can be configured to consist of first focusing lens 31 and second focusing lens 32. The first focusing lens 31 and second focusing lens 32 form a 4F system to expand the excitation beam.

[0045] In a more specific embodiment, the ultrasonic transducer 7 is a needle-shaped ultrasonic transducer 7. The coupling solution is deionized water.

[0046] To improve the quality of the ultrasonic signal generated by the coupling of the sample, deionized water can be used as the coupling solution. Furthermore, to improve the detection efficiency of the ultrasonic signal, the ultrasonic transducer 7 can be configured as a needle-shaped ultrasonic transducer 7. The needle-shaped ultrasonic transducer 7 can accurately detect the ultrasonic waves generated at the excitation site irradiated by the excitation beam, thereby efficiently acquiring the ultrasonic signal.

[0047] The imaging system disclosed in this invention is based on speckle variance and is suitable for enhanced imaging of blood vessels. First, compared to traditional melanoma biopsy diagnosis, the method proposed in this invention is a non-invasive, label-free, and rapid in vivo imaging method, which can reduce harm and pain to patients and improve diagnostic timeliness. Second, by combining the advantages of rapid scanning with an optical galvanometer and repeatedly scanning the same site of the sample with a scanning beam, rapid imaging of the morphological information of blood vessels inside melanoma can be achieved. Third, the imaging system requires only one excitation light source, making the system simple, reliable, and easy to develop, thus saving system costs. Fourth, compared to single-scan photoacoustic imaging technology, this invention can obtain richer morphological information of blood vessels.

[0048] This application also provides a photoacoustic enhancement imaging method based on speckle variance. Please refer to [link to relevant documentation]. Figure 2 As shown in the figure, the imaging method includes steps S110 to S140.

[0049] S110: The laser is turned on to emit a laser beam, which is modulated by the modulation component and expanded by the beam expander component before entering the optical galvanometer.

[0050] First, the plane to be imaged on the sample can be adjusted to be at the focal point of the beam emitted from the objective lens. Then, the laser is activated to emit a laser beam, which is modulated by the modulation component and expanded by the beam expander before entering the optical galvanometer. The laser wavelength emitted by the laser is 500-565nm, preferably 532nm.

[0051] S120, the optical galvanometer performs a scanning operation according to the received galvanometer control signal to generate a scanning beam and inject it into the objective lens. The objective lens focuses the scanning beam and illuminates the sample and scans the sample. The sample is excited by the scanning beam to generate ultrasonic waves, which are then transmitted to the ultrasonic detector through the coupling solution.

[0052] The imaging processing terminal can transmit motion commands to the galvanometer controller. The galvanometer controller outputs corresponding galvanometer control signals (different control voltages) according to the motion commands to control the optical galvanometer. The optical galvanometer performs a scanning operation according to the received galvanometer control signals, thereby generating a scanning beam to scan the sample. The sample is excited by the scanning beam to generate ultrasonic waves.

[0053] S130, the data acquisition card acquires the ultrasonic signals detected by the ultrasonic transducer and transmits them to the imaging processing terminal in real time.

[0054] The data acquisition card acquires the ultrasonic signals detected by the ultrasonic transducer and transmits them to the imaging processing terminal in real time.

[0055] S140 The imaging processing terminal uses a speckle variance extraction algorithm to perform imaging processing on the ultrasonic signals obtained from multiple scanning sites to generate sample images.

[0056] The imaging processing terminal performs imaging processing on the ultrasound signals obtained from multiple scanning sites. Each point corresponds to multiple scans, resulting in multiple ultrasound signals per point. The speckle variance of the ultrasound signal fluctuations across multiple scans at the same location can be calculated based on a speckle variance extraction algorithm. At locations with flowing red blood cells, the ultrasound signals acquired at different times vary significantly (including amplitude and depth), resulting in a larger calculated speckle variance. In contrast, the photoacoustic signal (ultrasound signal) in static melanin tissue is caused by noise, leading to a smaller speckle variance. Since the ultrasound signal itself contains depth information, its fluctuations include both amplitude and depth variations. The superposition of depth and amplitude variations in the photoacoustic signal at the same location significantly improves the signal-to-noise ratio of the dynamically extracted enhanced vascular image. The speckle variance extraction algorithm can be expressed using the following formula:

[0057]

[0058] Among them, A v,m S is the photoacoustic signal obtained from the m-th scan of the v-th site in the sample, where M is the preset number of scans, which ranges from 4 to 8. v,m The speckle variance value is calculated based on the ultrasound signals from multiple scans of the v-th site in the sample. Multiple acquisitions of ultrasound signals from the same site constitute multiple photoacoustic B-scan images. The number of times photoacoustic B-scan images are repeatedly acquired at the same lateral position determines the imaging time. To compare the ability of speckle variance-based vascular enhancement methods to suppress static tissue noise without reducing flowing blood signal, we introduce the contrast-to-noise ratio (CNR) to evaluate the impact of the number of repeated scans on the quality of vascular enhancement images. In vascular enhancement images, the average intensity of the blood vessel portion is greater than the average intensity of static tissue noise. To prevent the intensity range of the blood vessel image and the static tissue intensity range from overlapping, which could lead to misinterpretation of vascular information as static tissue noise and loss of vascular morphological information, the intensity variance of the enhanced blood vessel and the intensity variance of the static tissue should be as small as possible. The contrast-to-noise ratio (CNR) is implemented based on this principle. The preset number of scans can be set to 4-8.

[0059] In the phantom experiment, the contrast-to-noise ratio (CNR) was positively correlated with the number of repeated scans. When the number of repeated scans was less than 6, increasing the number of B-Scan scans caused a rapid increase in CNR. When the number of repeated scans was greater than 6, increasing the number of B-Scan scans resulted in a gradual increase in CNR. Considering both image quality and imaging speed, 6 repeated scans were selected, meaning the preferred preset scan number was 6. The formula for contrast-to-noise ratio (CNR) is as follows:

[0060]

[0061] μ b It is the mean of static tissue signal intensity, μ s It is the mean intensity of the blood vessel image. It is the variance of static tissue strength. It represents the variance of the intensity of the blood vessel image.

[0062] Multiple photoacoustic B-Scan images were acquired at the same location, and then speckle variance calculation was performed on the image set to extract the morphological information of blood vessels inside the melanoma. The number of repeated photoacoustic B-Scan scans was determined using an image evaluation system based on contrast-to-noise ratio (CNR). Validation through phantom experiments showed that only 6 repeated B-Scan scans were needed to achieve high-quality vascular enhancement imaging. First, in terms of photoexcitation, a galvanometer was used to perform high-speed scanning of 532nm wavelength excitation light. The galvanometer's own fast deflection speed ensured rapid multiple scans of the same spatial location of the biological sample. Since only 6 repeated B-Scan scans were needed, the entire imaging time was only 2 minutes. Second, speckle variance calculation was performed on the photoacoustic image set at the same spatial location to calculate the speckle variance of the photoacoustic signal amplitude fluctuations in the photoacoustic image set, extracting the morphological information of the blood vessels. Then, a threshold was used to distinguish blood vessels and noise in the vascular enhancement image, filtering out noise caused by fluctuations in the photoacoustic signal of static tissue. These two measures enable the present invention to acquire images of the enhanced internal blood vessels and enhanced three-dimensional microscopic morphological structure of melanoma in a "high-speed, label-free, and highly sensitive" manner.

[0063] This invention has been experimentally verified. The developed photoacoustic enhancement imaging system based on speckle variance has been experimentally verified in live mice. Multiple photoacoustic B-Scan images were acquired at the same lateral position, and speckle variance calculations were performed to obtain photoacoustic vascular enhancement imaging, acquiring morphological information of the blood vessels. Among these, Figure 3 Static images of melanoma; Figure 4 Photoacoustic enhanced images of blood vessels; Figure 5 This image is obtained by fusing a static image of a melanoma and an image with enhanced photoacoustic contrast on blood vessels.

[0064] Photoacoustic imaging was performed on the ears of mice inoculated with melanoma. Because the photoacoustic signal of melanin is much greater than that of hemoglobin, the vascular images almost disappeared into the background, making it impossible to observe the morphology and structure of the blood vessels. Figure 3 ). Figure 4 Based on speckle variance-based photoacoustic angiography, the morphological structure of the vascular network was clearly obtained, confirming the feasibility of the present invention. Figure 5 It is a high-contrast, label-free image of the fused melanoma and its nourishing blood vessels.

[0065] This invention provides a speckle variance-based photoacoustic enhancement imaging system and method. The imaging system includes a laser, a modulation component, a beam expander, an optical galvanometer, an objective lens, a container, an ultrasonic transducer, a galvanometer controller, a data acquisition card, and an imaging processing terminal. Compared with existing technologies, this invention utilizes the dynamic changes in amplitude and position of photoacoustic signals emitted by flowing red blood cells over time. It employs optical scanning to perform rapid, multiple scans at the same site to obtain multiple ultrasonic signals from the same location. By processing the ultrasonic signals from the multiple sites obtained through a speckle variance extraction algorithm, photoacoustic vascular enhancement images based on speckle variance can be obtained, significantly improving imaging efficiency. This enables non-invasive, label-free, specific, high-contrast, and high-resolution imaging of melanoma and nutrient vessels.

[0066] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in the present invention, and these modifications or substitutions should all be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A photoacoustic enhancement imaging system based on speckle variance, characterized in that, The system includes a laser, modulation components, beam expander components, optical galvanometer, objective lens, container, ultrasonic transducer, galvanometer controller, data acquisition card, and imaging processing terminal. The laser is positioned upstream of the beam expander assembly, and the modulation assembly is positioned between the laser and the beam expander assembly; the optical galvanometer is positioned downstream of the beam expander assembly; and the objective lens is positioned downstream of the optical galvanometer. The ultrasonic transducer is disposed inside the container, which contains a coupling solution, and the sample is placed inside the container; the objective lens is disposed above the container, and the ultrasonic transducer is disposed to the side of the sample. The optical galvanometer is connected to the galvanometer controller, the ultrasonic transducer is connected to the data acquisition card, and the imaging processing terminal is connected to both the galvanometer controller and the data acquisition card. The laser generated by the laser is transmitted into the optical galvanometer via the modulation component; the galvanometer controller sends a galvanometer control signal to control the optical galvanometer to perform a scanning operation to generate a scanning beam; the scanning beam is transmitted into the objective lens and focused. The focused beam emitted from the objective lens illuminates the sample; The data acquisition card acquires the ultrasonic signals detected by the ultrasonic transducer and outputs them to the imaging processing terminal; the imaging processing terminal processes the ultrasonic signals obtained from multiple scanning sites using a speckle variance extraction algorithm to generate sample images, with each point corresponding to a preset number of scans.

2. The photoacoustic enhancement imaging system based on speckle variance according to claim 1, characterized in that, The sample is placed at the focal point of the beam emitted from the objective lens.

3. The photoacoustic enhancement imaging system based on speckle variance according to claim 1, characterized in that, The laser is a green laser.

4. The photoacoustic enhancement imaging system based on speckle variance according to any one of claims 1-3, characterized in that, The modulation component includes a polarizer and a half-wave plate; the polarizer is disposed upstream of the half-wave plate.

5. The photoacoustic enhancement imaging system based on speckle variance according to claim 4, characterized in that, The beam expander assembly includes a first focusing lens and a second focusing lens.

6. The photoacoustic enhancement imaging system based on speckle variance according to claim 5, characterized in that, The ultrasonic transducer is a needle-shaped ultrasonic transducer.

7. The photoacoustic enhancement imaging system based on speckle variance according to any one of claims 1-3, characterized in that, The coupling solution is deionized water.

8. A photoacoustic enhancement imaging method based on speckle variance, characterized in that, The imaging method is applied to the imaging system as described in any one of claims 1-7, the imaging method comprising: The laser is turned on to emit a laser beam, which is modulated by the modulation component and expanded by the beam expander component before entering the optical galvanometer. The optical galvanometer performs a scanning operation according to the received galvanometer control signal to generate a scanning beam and shoot it into the objective lens. The objective lens focuses the scanning beam and illuminates the sample and scans the sample. The sample is excited by the scanning beam to generate ultrasonic waves, which are then propagated to the ultrasonic detector through the coupling solution. The data acquisition card acquires the ultrasonic signals detected by the ultrasonic transducer and transmits them to the imaging processing terminal in real time. The imaging processing terminal uses a speckle variance extraction algorithm to process the ultrasound signals from multiple sites obtained during scanning to generate sample images.

9. The photoacoustic enhancement imaging method based on speckle variance according to claim 8, characterized in that, The formula corresponding to the speckle variance extraction algorithm is: ; Among them, A v,m S is the photoacoustic signal obtained from the m-th scan of the v-th site in the sample, where M is the preset number of scans, which ranges from 4 to 8. v,m The speckle variance value is calculated based on the ultrasonic signals from multiple scans of the v-th site in the sample.

Images