Photoacoustic microscope system and imaging method

Abstract

The present invention discloses a high-speed, large-field photoacoustic microscope system and imaging method. The system includes a carrying device, an excitation light generating device, an objective lens, a detection light generating device, an optical surface wave sensor and a total reflection film; wherein the processing and control device is used to control the movement of the excitation light beam and the detection light beam, so that the excitation light beam and the detection light beam move coaxially and synchronously; the total reflection film is used to fully reflect the detection light beam, so that the detection light beam is fully reflected in the original light path direction, and the processing and control device is also used to split the detection light beam, synthesize the photoacoustic signal and reconstruct the image to obtain the target image. The system is based on the photoacoustic detection principle of the optical surface wave sensor, realizes the purpose of high-sensitivity and large-bandwidth detection of the photoacoustic signal, and at the same time improves the signal-to-noise ratio and depth resolution of the imaging, and realizes the purpose of coaxial, synchronous and rapid scanning of the tissue sample by the two light beams by controlling the excitation light beam and the detection light beam, which can greatly shorten the imaging time and increase the imaging field of view.

Description

Technical Field

[0001] The present invention relates to the field of microscopic imaging, and in particular to a photoacoustic microscope system and an imaging method. Background Art

[0002] At present, mechanical scanning methods in photoacoustic imaging have the problems of slow imaging speed and long imaging time due to the limitations of the precision displacement platform and the accuracy requirements of photoacoustic imaging. Therefore, photoacoustic imaging technology uses fast optical scanning mechanisms such as galvanometers to improve the imaging speed. Fast photoacoustic imaging technology has shown many advantages, prompting many university scholars to invest in this field. For example, South China Normal University has developed optical imaging technology based on galvanometer scanning for cell and blood vessel imaging. The system composed of galvanometers, optical microscopes and ultrasound detectors is used for in vivo mouse ear vascular imaging, and the photoacoustic image of mouse ear blood vessels is clearly reconstructed; in 2009, scholars from the University of Wisconsin and the University of Southern California cooperated to invent a laser scanning optical resolution photoacoustic microscope, which keeps the ultrasonic transducer stationary and uses an XY galvanometer scanner to only raster scan the laser to obtain images.

[0003] However, in photoacoustic microscopy technology based on optical scanning, most systems use non-focused piezoelectric ultrasonic transducers, which have the disadvantages of narrow bandwidth and small detection angle of view, resulting in poor depth resolution and narrow field of view. These defects limit the application of photoacoustic imaging technology in the biomedical field. Summary of the invention

[0004] The purpose of the present invention is to provide a photoacoustic microscope system and an imaging method, aiming to solve the problems of poor depth resolution, narrow field of view and slow imaging speed in existing photoacoustic microscopy imaging technology.

[0005] In order to solve the above technical problems, the object of the present invention is achieved through the following technical solutions: a photoacoustic microscope system is provided, which comprises:

[0006] A carrying device, used for carrying a tissue sample and a deionized water layer, wherein the tissue sample is immersed in the deionized water layer;

[0007] An excitation light generating device, used for generating an excitation light beam;

[0008] an objective lens, used for focusing the excitation light beam so that the excitation light beam is incident on the tissue sample through the carrying device, wherein the tissue sample emits an ultrasonic signal under the excitation of the excitation light beam;

[0009] A detection light generating device, used for generating a detection light beam;

[0010] A processing and control device, used for controlling the movement of the excitation light beam and the detection light beam, so that the excitation light beam and the detection light beam move coaxially and synchronously;

[0011] An optical surface wave sensor, used to receive an incoming detection beam, wherein the detection beam passes through one side of the optical surface wave sensor and is incident on the bottom of the optical surface wave sensor and is reflected to the other side of the optical surface wave sensor, and the detection beam is used to receive the ultrasonic signal;

[0012] A total reflection film, used for totally reflecting the detection light beam, so that the detection light beam is totally reflected in the original light path direction, wherein the total reflection film is arranged on the other side of the optical surface wave sensor;

[0013] The processing and control device is also used to receive the returned detection light beam, and perform beam splitting, photoacoustic signal synthesis and image reconstruction on the detection light beam to obtain a target image.

[0014] In addition, the technical problem to be solved by the present invention is to provide an imaging method using the photoacoustic microscope system as described above, which comprises:

[0015] The excitation light generating device outputs an excitation light beam, and the detection light generating device outputs a detection light beam;

[0016] The objective lens focuses the excitation light beam so that the excitation light beam is incident on the tissue sample through the carrying device, wherein the tissue sample emits an ultrasonic signal under the excitation of the excitation light beam;

[0017] The processing and control device controls the movement of the excitation light beam and the detection light beam so that the excitation light beam and the detection light beam move coaxially and synchronously;

[0018] The optical surface wave sensor receives the detection beam, wherein the detection beam passes through one side of the optical surface wave sensor and is incident on the bottom of the optical surface wave sensor and is reflected to the other side of the optical surface wave sensor, and the detection beam is used to receive the ultrasonic signal;

[0019] The total reflection film totally reflects the detection light beam, so that the detection light beam is totally reflected in the original light path direction, wherein the total reflection film is arranged on the other side of the optical surface wave sensor;

[0020] The processing and control device receives the returned detection light beam and performs beam splitting, photoacoustic signal synthesis and image reconstruction processing to obtain a target image.

[0021] The embodiment of the present invention discloses a photoacoustic microscope system and an imaging method, wherein the system includes: a carrying device for carrying a tissue sample and a deionized water layer, wherein the tissue sample is immersed in the deionized water layer; an excitation light generating device for generating an excitation light beam; an objective lens for focusing the excitation light beam so that the excitation light beam passes through the carrying device and is incident on the tissue sample, wherein the tissue sample emits an ultrasonic signal under the excitation of the excitation light beam; a detection light generating device for generating a detection light beam; and a processing and control device for controlling the movement of the excitation light beam and the detection light beam so that the excitation light beam and the detection light beam are coaxially synchronized. movement; an optical surface wave sensor, used to receive an incoming detection beam, wherein the detection beam passes through one side of the optical surface wave sensor and is incident on the bottom of the optical surface wave sensor and is reflected to the other side of the optical surface wave sensor, and the detection beam is used to receive the ultrasonic signal; a total reflection membrane, used to totally reflect the detection beam, so that the detection beam is totally reflected in the original light path direction, wherein the total reflection membrane is arranged on the other side of the optical surface wave sensor; the processing and control device is also used to receive the returned detection beam, and perform beam splitting, photoacoustic signal synthesis and image reconstruction processing on the detection beam to obtain a target image.

[0022] The system is based on the photoacoustic detection principle of optical surface wave sensors, achieving high-sensitivity, wide-bandwidth detection of photoacoustic signals, improving the signal-to-noise ratio and depth resolution of photoacoustic microscopy. At the same time, by controlling the coaxial, synchronous, and rapid scanning of the excitation beam and the detection beam, the imaging time is greatly shortened and the imaging field of view is increased. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying any creative work.

[0024] Figure 1 A schematic diagram of the structure of a photoacoustic microscope system provided by an embodiment of the present invention;

[0025] Figure 2 A schematic flow chart of an imaging method of a photoacoustic microscope system provided in an embodiment of the present invention.

[0026] Description of reference numerals:

[0027] 1. Carrying device; 2. Excitation light generating device; 3. Objective lens; 4. Detection light generating device; 5. Optical surface wave sensor; 6. First group of optical galvanometers; 7. Controller; 8. Second group of optical galvanometers; 9. First polarizer; 10. First half-wave plate; 11. Fifth reflector; 12. Third lens; 13. First beam splitter; 14. Second beam splitter; 15. First analyzer; 16. Second analyzer; 17. First reflector; 18. Second reflector; 19. Third reflector; 20. Fourth reflector; 21. First lens; 22. Second lens; 23. Differential detector; 24. Processing terminal; 25. Second polarizer; 26. Second half-wave plate; 27. Total reflection film. DETAILED DESCRIPTION

[0028] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] It should be understood that when used in this specification and the appended claims, the terms "include" and "comprises" indicate the presence of described features, integers, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or combinations thereof.

[0030] It should also be understood that the terms used in this specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. As used in the specification of the present invention and the appended claims, unless the context clearly indicates otherwise, the singular forms "a", "an" and "the" are intended to include plural forms.

[0031] It should be further understood that the term "and / or" used in the present description and the appended claims refers to any and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0032] It should be noted that photoacoustic imaging is a booming biomedical imaging technology and the only imaging technology that can directly observe the intrinsic absorption contrast information in vivo. This technology mainly includes two physical processes: the generation and detection of photoacoustic waves. It detects substances with strong optical absorption characteristics such as hemoglobin and melanin. After absorbing short-pulse lasers, the transient thermoelastic effect generates ultrasonic waves related to their size and absorption coefficient, thereby achieving specific observation of their optical absorption characteristics. The optical absorption characteristic measurement of photoacoustic imaging has an efficiency of 100%, which is two orders of magnitude higher than confocal microscopy and optical coherence tomography. It shows great application prospects in life sciences and clinical diagnosis fields such as brain science and oncology.

[0033] Although photoacoustic imaging has made great progress, most photoacoustic imaging systems currently use mechanical scanning to move the sample to be tested or the imaging probe to obtain the photoacoustic microscopic image of the sample. Since photoacoustic imaging is applied to biological tissue imaging, and the characteristics of biological tissue miniaturization and refinement are required, the movement step of the displacement platform is required to be fine enough, and a sufficient number of steps are required, which leads to a long image acquisition time and is difficult to meet actual needs. In order to increase the imaging speed, optical scanning has been introduced into the field of photoacoustic imaging. Photoacoustic imaging is usually performed by combining a non-focusing piezoelectric transducer and an optical galvanometer, and the imaging time can be shortened to a few seconds. However, non-focusing piezoelectric transducers have defects such as low sensitivity, small detection angle of view, and narrow detection bandwidth, which leads to many problems such as poor depth resolution of photoacoustic imaging, limited imaging field of view, and low image quality.

[0034] In order to solve the above technical problems, this embodiment provides a photoacoustic microscope system to obtain photoacoustic microscopic images of the three-dimensional microscopic morphological structure of biological samples with "high speed, large field of view, and high resolution".

[0035] See also Figure 1 , Figure 1 A schematic diagram of the structure of a photoacoustic microscope system provided by an embodiment of the present invention;

[0036] like Figure 1 As shown, the system includes:

[0037] A carrying device 1, used for carrying a tissue sample and a deionized water layer, wherein the tissue sample is immersed in the deionized water layer;

[0038] An excitation light generating device 2, used for generating an excitation light beam;

[0039] A detection light generating device 4, used for generating a detection light beam;

[0040] an objective lens 3, used for focusing the excitation light beam so that the excitation light beam is incident on the tissue sample through the carrier device 1, wherein the tissue sample emits an ultrasonic signal under the excitation of the excitation light beam;

[0041] A processing and control device, used for controlling the movement of the excitation light beam and the detection light beam, so that the excitation light beam and the detection light beam move coaxially and synchronously, so as to perform synchronous scanning on the tissue sample;

[0042] The optical surface wave sensor 5 is used to receive a detection beam, wherein the detection beam passes through one side of the optical surface wave sensor 5 and is incident on the bottom of the optical surface wave sensor 5 and is reflected to the other side of the optical surface wave sensor 5, and the detection beam is used to receive the ultrasonic signal;

[0043] A total reflection film 27, used for totally reflecting the detection light beam, so that the detection light beam is totally reflected in the original light path direction, wherein the total reflection film 27 is arranged on the other side of the optical surface wave sensor 5;

[0044] The processing and control device is also used to receive the returned detection light beam, and perform beam splitting, photoacoustic signal synthesis and image reconstruction on the detection light beam to obtain a target image.

[0045] In an actual use scenario, a tissue sample (not shown in the figure) immersed in a deionized water layer (not shown in the figure) is first placed on the upper side of the carrier 1, and then the excitation light generating device 2 and the detection light generating device 4 are simultaneously started to output an excitation light beam and a detection light beam respectively, and the objective lens 3 focuses the excitation light beam so that the excitation light beam passes through the carrier 1 and is incident on the tissue sample; Figure 1 Point a, point b, and point c shown are the positions where the excitation light beam hits different positions of the tissue sample at different times. Point a, point b, and point c can also be connected to form a path line, that is, under the control of the processing and control device, the excitation light beam scans the tissue sample from point a, through point b, to point c, so that the tissue sample emits an ultrasonic signal under the excitation of the excitation light beam. It should be noted that the scan is a two-dimensional scan, and point a, point b, and point c respectively represent the incident conditions of the three light beams at different times, which is intended to show the deflection of the excitation light beam.

[0046] The detection beam also moves under the control of the processing and control device, following the movement of the excitation beam, that is, in the process of the excitation beam moving from point a, through point b, to point c, the detection beam moves along the path of point a′, through point b′, to point c′. It should be noted that the present application does not make specific restrictions on the order of scanning positions; in addition, the detection beam only receives the ultrasonic signal excited by the excitation beam and undergoes corresponding phase changes, and is not directly incident on the tissue sample.

[0047] When the excitation light beam is irradiated at point a of the tissue sample, the detection light beam is correspondingly irradiated at position a′ above the tissue sample. Similarly, when the excitation light beam is irradiated at point b of the tissue sample, the detection light beam is correspondingly irradiated at position b′ above the tissue sample. This allows the excitation light beam and the detection light beam to coaxially move synchronously to perform synchronous scanning of the tissue sample. During the imaging process, the tissue sample remains stationary. Such a design achieves high-sensitivity detection of photoacoustic signals, ensuring rapid, large-field-of-view acquisition of biological sample information.

[0048] It should be noted that the tissue sample will emit an ultrasonic signal (ultrasound) under the action of the excitation light beam, and the ultrasonic signal will cause the refractive index of water to change. The ultrasonic signal propagates in the coupling medium water to the inner wall (upper surface) of the optical surface wave sensor 5, and interacts with the evanescent field, wherein the evanescent field is generated when the detection light beam undergoes total internal reflection. That is to say, the excitation light beam acts on the tissue sample, and the tissue sample emits ultrasonic information, which is first transmitted to the water, and then the detection light beam receives this information (that is, the phase change) when passing through the interface between the optical surface wave sensor 5 and the water, and finally obtains the required image information by detecting the phase change.

[0049] At the same time, in this embodiment, in terms of photoacoustic signal detection, optical surface wave sensing technology is introduced, and optical surface wave sensor 5 (i.e., total reflection optical sensor) is used for photoacoustic wave detection. The sensor can ensure that the detection light beam returns to its original path, thereby achieving high-sensitivity and broadband detection of photoacoustic waves, and significantly improving the signal-to-noise ratio and depth resolution capability of photoacoustic imaging.

[0050] In a specific embodiment, the optical surface wave sensor 5 is placed above the tissue sample, and the objective lens 3 is located below the tissue sample.

[0051] Through such a design, the structure of the entire microscope system is made more compact.

[0052] In a specific embodiment, the shape of the optical surface wave sensor 5 is set to be an isosceles trapezoid or a rectangle, and the total reflection film 27 is a gold film or a silver film.

[0053] In this embodiment, it should be noted that the shape of the optical surface wave sensor 5 is not limited to an isosceles trapezoidal prism or a rectangular prism. The present application prefers to set the shape of the optical surface wave sensor 5 to an isosceles trapezoidal prism because the isosceles trapezoidal prism has a larger field of view than prisms of other shapes.

[0054] In addition, the detection light beam is preferably returned through the gold film 27 or the silver film. Depending on the actual situation, the detection light beam can also be returned by using films of other materials, and this application does not make any specific limitations. Specifically, the gold film 27 or the silver film is fixedly arranged on an inner wall of the isosceles trapezoidal prism away from the second group of optical galvanometers 8, so that the detection light beam can be incident on the tissue sample from the other inner wall opposite to the optical surface wave sensor 5, and then reflected onto the gold film 27 or the silver film, and finally totally reflected back to the second group of optical galvanometers 8 in the direction of the original light path.

[0055] In a specific embodiment, the excitation light generating device 2 is a laser with a wavelength of 532 nm or 266 nm; the detection light generating device 4 is a pulsed laser with a wavelength of 632.8 nm.

[0056] It should be noted that an excitation light beam with a wavelength of 532nm is commonly used for melanin imaging in the eye, while an excitation light beam with a wavelength of 266nm is often used in the optimal band for nucleus imaging. At the same time, in actual usage scenarios, red light with a wavelength of 632.8nm is often used as a detection light beam.

[0057] It is worth noting that the initial detection light beam is not limited to linearly polarized light, but can also be elliptically or circularly polarized light, depending on the highest signal sensitivity; the wavelength of the photoacoustic excitation light beam is not limited to 532nm, and the wavelength can be changed for different samples, based on the maximum absorption coefficient of the sample and the strongest photoacoustic signal generated; the detection light wavelength is not limited to 632.8nm, and different detection light wavelengths correspond to different excitation angles.

[0058] In a specific embodiment, the processing and control device includes a first group of optical galvanometers 6 and a controller 7 connected to the first group of optical galvanometers 6 by signal. The first group of optical galvanometers 6 is located between the excitation light generating device 2 and the objective lens 3. The controller 7 is used to control the movement of the first group of optical galvanometers 6 based on a movement instruction.

[0059] Specifically, the first group of optical galvanometers 6 is located below the objective lens 3, and in the present embodiment, the first group of optical galvanometers 6 includes two optical galvanometers, the excitation light generating device 2 emits an excitation light beam, the excitation light beam is incident on one of the optical galvanometers along the light path direction, then reflected on the other optical galvanometer, and finally reflected on the objective lens 3 through the optical galvanometer. In the process of scanning the tissue sample, it is only necessary to control the movement of one or two optical galvanometers through the controller 7, that is, to change the deflection angle of one or both optical galvanometers at the same time to change the position where the excitation light beam is incident on the tissue sample; the use of two optical galvanometers can significantly expand the imaging field of view, so that the photoacoustic imaging has the characteristics of high speed and large field of view while having good imaging sensitivity.

[0060] In a specific embodiment, the processing and control device also includes a second group of optical galvanometers 8 connected to the controller 7 by signal, and the second group of optical galvanometers 8 is located between the detection light generating device 4 and the optical surface wave sensor 5. The controller 7 is also used to control the movement of the second group of optical galvanometers 8 based on a movement instruction.

[0061] Specifically, the second group of optical galvanometers 8 is located on one side of the optical surface wave sensor 5, and two second group of optical galvanometers 8 are provided. It should be noted that the use principle of the second group of optical galvanometers 8 is consistent with that of the first group of optical galvanometers 6. The movement of the first group of optical galvanometers 6 and the second group of optical galvanometers 8 is simultaneously controlled by the controller 7, thereby realizing the coaxial synchronous movement of the excitation light beam and the detection light beam to perform synchronous scanning of the tissue sample, that is, for example, when the excitation light beam is irradiated at point a of the tissue sample, the detection light beam is correspondingly irradiated at position a′ of the tissue sample.

[0062] In a specific embodiment, a plurality of polarizers, half-wave plates, reflectors and lenses are sequentially arranged along the light path between the excitation light generating device 2 and the first group of optical galvanometers 6 , wherein the lens is used to expand the excitation light beam.

[0063] Specifically, the polarizer (i.e. Figure 1 The first polarizer 9 shown), the half-wave plate (i.e. Figure 1 The first half-wave plate 10 shown in the figure is provided with only one reflector (i.e. Figure 1 The fifth reflector 11 shown in the figure is provided with two lenses (i.e. Figure 1 There are two third lenses 12 shown in the figure, and the two third lenses 12 constitute a 4F system, which can amplify the light spot, which is equivalent to expanding the excitation light beam, so that the expanded excitation light beam can fill the mirror surface of one of the optical galvanometers in the first group of optical galvanometers 6 to the maximum extent, that is, the excitation light beam can better fill the back aperture of the objective lens 3 through the expansion operation, thereby improving the imaging resolution, wherein the first polarizer 9 is used to modulate the incident light beam (that is, the excitation light beam in the present embodiment) into standard linear polarized light, the first half-wave plate 10 is used to adjust the polarization direction of the linear polarized light, and the two fifth reflectors 11 are used to reflect the excitation light beam and change the propagation direction of the excitation light beam.

[0064] In a specific embodiment, the processing and control device further includes a first beam splitting device 13, a second beam splitting device 14, a first polarizer 15, a second polarizer 16, a first reflector 17, a second reflector 18, a third reflector 19, a fourth reflector 20, a first lens 21 and a second lens 22, a differential detector 23 and a processing terminal 24;

[0065] The first beam splitting device 13 is located between the second group of optical galvanometers 8 and the detection light generating device 4;

[0066] The second beam splitting device 14 is located on the reflected light path of the first beam splitting device 13, and outputs the first beam splitting device and the second beam splitting device;

[0067] The first analyzer 15, the first reflector 17, the second reflector 18 and the first lens 21 are sequentially located in the optical path direction of the first split beam;

[0068] The second analyzer 16, the third reflector 19, the fourth reflector 20 and the second lens 22 are sequentially located in the optical path direction of the second split beam;

[0069] The differential detector 23 receives the first and second beams transmitted by the first lens 21 and the second lens 22, and performs photoacoustic signal synthesis;

[0070] The processing terminal 24 is signal-connected to the differential detector 23 and is used to receive the synthesized photoacoustic signal and perform data analysis and image reconstruction.

[0071] Specifically, the first beam splitting device 13 and the second beam splitting device 14 are both beam splitters, and are both used to split the detection light into two beams for different operations. The first polarizer 15 and the second polarizer 16 are used to adjust the polarization direction. The first reflector 17, the second reflector 18, the third reflector 19, and the fourth reflector 20 are all used to reflect the light beam and change the propagation direction of the light beam. The first lens 21 and the second lens 22 are both used to focus or collimate the detection light beam. The differential detector 23 is used to detect the high-speed changing s and p light intensity difference.

[0072] In a specific embodiment, a plurality of polarizers and half-wave plates are sequentially arranged between the detection light generating device 4 and the first beam splitting device 13 along the light path direction.

[0073] Specifically, the polarizer in this embodiment (ie Figure 1 The second polarizing plate 25 shown in the figure is provided with a half-wave plate (i.e. Figure 1 The second half-wave plate 26 shown is provided with a second polarizer 25 for modulating the incident light beam into standard linear polarized light, and the second half-wave plate 26 for adjusting the polarization direction of the linear polarized light.

[0074] In the actual imaging process, a pulsed laser with a wavelength of 632.8 nm is used as the detection light source. The polarization state is modulated by the second polarizer 25 and the second half-wave plate 26, and then incident on the second group of optical galvanometers 8 after passing through the first beam splitter 13 to adjust the detection light beam to ensure coaxial synchronous movement with the excitation light beam. After reflection, the detection light is incident on the coating layer (gold film 27 or silver film) of the optical surface wave sensor 5, and full emission occurs. The detection light beam returns along the original optical path and returns to the first beam splitter 13 for beam splitting. After beam splitting, one beam enters the second beam splitter 14, wherein the beam splitting ratio of the second beam splitter 14 is 50:50. After the detection light beam is divided into two equal beams, the two detection light beams are transmitted to two polarizers respectively, and the deflection directions of the two are respectively along the short axis direction and the long axis direction of the elliptically polarized light beam. The efficiency of converting the phase difference of the s and p light beams caused by the acoustic wave in the short axis direction into light intensity is high, and it is mainly used for sensing. The conversion efficiency in the long axis direction is low, and it is used as a reference arm.

[0075] One of the detection light beams is deflected by the first reflector 17 and the second reflector 18 in sequence, and then focused by the first lens 21, and the other detection light beam is deflected by the third reflector 19 and the fourth reflector 20 in sequence, and then focused by the second lens 22, so that the two detection light beams can enter the two detection units of the differential detector 23 in parallel, and finally the differential detector 23 realizes the detection of the photoacoustic signal, that is, after the differential detector 23 receives the detection light beam, the s and p polarization phase differences caused by the two light beams are differentially synthesized, and the output signal is a photoacoustic signal, and finally the photoacoustic signal is stored in the processing terminal 24 for subsequent data analysis and image reconstruction.

[0076] It should be noted that the device for decomposing the mixed light beam into s-polarized light and p-polarized light in the present application is not limited to a polarization beam splitter (PBS) but also includes polarization beam splitting devices such as a Wollaston prism.

[0077] In this embodiment, the processing terminal 24 includes but is not limited to a computer. LABVIEW is used on the computer host to write the galvanometer control program. During the operation process, the computer transmits movement instructions to the controller 7. The controller 7 transmits voltage to control the first group of optical galvanometers 6 and the second group of optical galvanometers 8, thereby ensuring coaxial synchronous scanning of the two groups of optical galvanometers.

[0078] The present application establishes the principle of photoacoustic detection based on the optical surface wave sensor 5, realizes high-sensitivity and wide-bandwidth detection of photoacoustic signals, and improves the signal-to-noise ratio and depth resolution of photoacoustic microscopy imaging. At the same time, based on the dual optical galvanometers, the excitation beam and the detection beam are coaxially, synchronously, and rapidly scanned, thereby greatly shortening the imaging time and improving the imaging sensitivity. In addition, the use of two optical galvanometers can significantly expand the imaging field of view, so that the photoacoustic imaging has the characteristics of high speed and large field of view while having good imaging sensitivity.

[0079] The embodiment of the present invention also provides an imaging method using the photoacoustic microscope system as described above, such as Figure 2 As shown, the method includes steps S101 to S106.

[0080] S101, the excitation light generating device 2 outputs an excitation light beam, and the detection light generating device 4 outputs a detection light beam;

[0081] S102, the objective lens 3 focuses the excitation light beam so that the excitation light beam passes through the carrying device and is incident on the tissue sample, wherein the tissue sample emits an ultrasonic signal under the excitation of the excitation light beam;

[0082] S103, the processing and control device controls the movement of the excitation light beam and the detection light beam, so that the excitation light beam and the detection light beam move coaxially and synchronously;

[0083] S104, the optical surface wave sensor 5 receives the detection beam, wherein the detection beam passes through one side of the optical surface wave sensor 5 and is incident on the bottom of the optical surface wave sensor 5, and is reflected to the other side of the optical surface wave sensor 5, and the detection beam is used to receive the ultrasonic signal;

[0084] S105, the total reflection film 27 totally reflects the detection light beam, so that the detection light beam is totally reflected in the original light path direction, wherein the total reflection film is arranged on the other side of the optical surface wave sensor 5;

[0085] S106, the processing and control device receives the returned detection light beam and performs beam splitting, photoacoustic signal synthesis and image reconstruction processing to obtain a target image.

[0086] In this embodiment, the method is based on the photoacoustic detection principle of the optical surface wave sensor 5, realizes high-sensitivity and wide-bandwidth detection of photoacoustic signals, and improves the signal-to-noise ratio and depth resolution of photoacoustic microscopy imaging. At the same time, based on the dual optical galvanometer, the excitation light beam and the detection light beam are coaxially, synchronously, and rapidly scanned, thereby greatly shortening the imaging time and improving the imaging sensitivity. In addition, the use of two optical galvanometers can significantly expand the imaging field of view, so that the photoacoustic imaging has the characteristics of high speed and large field of view while having good imaging sensitivity.

[0087] It should be noted that before step S102, the excitation light beam will first be expanded by the 4F system, and the light spot will fill the back aperture of the objective lens 3, thereby improving the light beam utilization and the imaging sensitivity.

[0088] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working process of the method described above can refer to the corresponding process in the aforementioned system embodiment, and will not be repeated here.

[0089] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can easily think of various equivalent modifications or replacements within the technical scope disclosed by the present invention, and these modifications or replacements should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be based on the protection scope of the claims.

Claims

1. A photoacoustic microscope system, characterized in that: include: A carrying device, used for carrying a tissue sample and a deionized water layer, wherein the tissue sample is immersed in the deionized water layer; An excitation light generating device, used for generating an excitation light beam; an objective lens, used for focusing the excitation light beam so that the excitation light beam is incident on the tissue sample through the carrying device, wherein the tissue sample emits an ultrasonic signal under the excitation of the excitation light beam; A detection light generating device, used for generating a detection light beam; A processing and control device, used for controlling the movement of the excitation light beam and the detection light beam, so that the excitation light beam and the detection light beam move coaxially and synchronously; An optical surface wave sensor, used for receiving a detection beam, wherein the detection beam passes through one side of the optical surface wave sensor and is incident on the bottom of the optical surface wave sensor and is reflected to the other side of the optical surface wave sensor, and the detection beam is used for receiving the ultrasonic signal; A total reflection film, used for totally reflecting the detection light beam, so that the detection light beam is totally reflected in the original light path direction, wherein the total reflection film is arranged on the other side of the optical surface wave sensor; The processing and control device is also used to receive the returned detection light beam, and perform beam splitting, photoacoustic signal synthesis and image reconstruction on the detection light beam to obtain a target image; The processing and control device includes a first group of optical galvanometers and a controller connected to the first group of optical galvanometers by signal, wherein the first group of optical galvanometers is located between the excitation light generating device and the objective lens, and the controller is used to control the movement of the first group of optical galvanometers based on a movement instruction; The processing and control device further comprises a second group of optical galvanometers connected to the controller signal, the second group of optical galvanometers being located between the detection light generating device and the optical surface wave sensor, and the controller is further used to control the movement of the second group of optical galvanometers based on the movement instruction; The processing and control device also includes a first beam splitting device, a second beam splitting device, a first analyzer, a second analyzer, a first reflector, a second reflector, a third reflector, a fourth reflector, a first lens and a second lens, a differential detector and a processing terminal; The first beam splitting device is located between the second group of optical galvanometers and the detection light generating device; The second beam splitting device is located on the reflected light path of the first beam splitting device and outputs the first beam splitting device and the second beam splitting device; The first analyzer, the first reflector, the second reflector and the first lens are sequentially located in the optical path direction of the first split beam; The second analyzer, the third reflector, the fourth reflector and the second lens are sequentially located in the optical path direction of the second split beam; The differential detector receives the first and second beams transmitted by the first and second lenses, and performs photoacoustic signal synthesis; The processing terminal is connected to the differential detector signal and is used to receive the synthesized photoacoustic signal and perform data analysis and image reconstruction.

2. The photoacoustic microscope system according to claim 1, characterized in that: A plurality of polarizers, half-wave plates, reflectors and lenses are sequentially arranged between the excitation light generating device and the first group of optical galvanometers along the light path direction, wherein the lens is used to expand the excitation light beam.

3. The photoacoustic microscope system according to claim 1, characterized in that: A plurality of polarizing plates and half-wave plates are sequentially arranged between the detection light generating device and the first beam splitting device along the light path direction.

4. The photoacoustic microscope system according to claim 1, characterized in that: The optical surface wave sensor is placed above the tissue sample, and the objective lens is located below the tissue sample.

5. The photoacoustic microscope system according to claim 1, characterized in that: The shape of the optical surface wave sensor is set to be an isosceles trapezoid or a rectangle, and the total reflection film is a gold film or a silver film.

6. The photoacoustic microscope system according to claim 1, characterized in that: The excitation light generating device is a laser with a wavelength of 532nm or 266nm; the detection light generating device is a pulse laser with a wavelength of 632.8nm.

7. An imaging method using the photoacoustic microscope system according to any one of claims 1 to 6, characterized in that: include: The excitation light generating device outputs an excitation light beam, and the detection light generating device outputs a detection light beam; The objective lens focuses the excitation light beam so that the excitation light beam is incident on the tissue sample through the carrying device, wherein the tissue sample emits an ultrasonic signal under the excitation of the excitation light beam; The processing and control device controls the movement of the excitation light beam and the detection light beam so that the excitation light beam and the detection light beam move coaxially and synchronously; The optical surface wave sensor receives the detection beam, wherein the detection beam passes through one side of the optical surface wave sensor and is incident on the bottom of the optical surface wave sensor and is reflected to the other side of the optical surface wave sensor, and the detection beam is used to receive the ultrasonic signal; The total reflection film totally reflects the detection light beam, so that the detection light beam is totally reflected in the original light path direction, wherein the total reflection film is arranged on the other side of the optical surface wave sensor; The processing and control device receives the returned detection light beam and performs beam splitting, photoacoustic signal synthesis and image reconstruction processing to obtain a target image.

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