Multi-channel photoacoustic microscopy imaging method and device

Abstract

The present invention relates to a multi-channel photoacoustic microscopy imaging method and device, comprising a light source, a beam expander, a digital micromirror array, a first lens, a second lens, a microlens array, a third lens, an objective lens, an ultrasonic point detector, and a sample motion stage; wherein the pulse laser emitted by the light source is incident on the digital micromirror array at a certain deflection angle after passing through the beam expander, and its reflected light is projected onto the microlens array through a group of first and second lenses with equal focal lengths, forming a multi-channel laser dot matrix on the focal plane of the microlens array, and then imaging onto the sample surface through the third lens and the objective lens, the multi-channel laser array is focused on the sample surface to stimulate the sample tissue to generate an ultrasonic signal, and the ultrasonic point detector receives the generated ultrasonic signal and reconstructs the sample target image after amplification and processing. The present invention uses a digital micromirror array and a microlens array to modulate the light beam, and has a fast imaging speed, a simple system structure, a low cost, and wide universality, and can be widely used in the field of medical imaging of biological tissues.

Description

Technical Field

[0001] The present invention belongs to the field of photoacoustic imaging, and in particular relates to a multi-channel photoacoustic microscopic imaging method and device. Background Art

[0002] Photoacoustic imaging is a non-invasive imaging technology that combines the high contrast of optical imaging and the high penetration of ultrasonic imaging. By irradiating the target tissue with a pulsed laser, the temperature of the tissue instantly rises and produces thermal elastic expansion, which then propagates outward in the form of ultrasonic waves. After the ultrasonic transducer obtains the ultrasonic signal, it processes the data and reconstructs the initial sound pressure distribution in the tissue, and then inverts the spatial distribution of the light absorption coefficient, thermal expansion characteristic parameters, etc., thereby obtaining information such as the structure and function of the tissue.

[0003] Photoacoustic microscopy (PAM) is an important way to achieve photoacoustic imaging. It can reflect the optical absorption characteristics of biological tissues through acoustic detection. It can overcome the limitations of pure optical microscopy and pure ultrasound imaging to a certain extent, and achieve high-resolution and high-contrast imaging of biological tissues. It has important applications in clinical medicine. An inevitable requirement for clinical imaging is fast imaging, and the mechanical scanning method of traditional photoacoustic microscopy (PAM) limits its scanning speed, hindering the further transformation of photoacoustic microscopy technology in clinical applications. The imaging speed of the photoacoustic microscopy system is related to the repetition frequency of the laser, the system scanning mechanism and the acquisition scheme of the ultrasonic signal. At present, most photoacoustic microscopy systems adopt the photoacoustic confocal point-by-point mechanical scanning method, including galvanometer scanning, micro-electromechanical system scanning, polygon mirror scanning, etc. The speed of this type of point-by-point scanning is still relatively slow compared to the imaging speed of the surface scanning method; in terms of ultrasonic signal acquisition scheme, a multi-element array ultrasonic transducer is used to synchronously acquire ultrasonic signals, which is faster than the traditional single ultrasonic transducer, but increases the complexity and cost of the system. For complex and diverse biological samples, there is still no photoacoustic microscopy imaging system that can simultaneously combine the characteristics of fast imaging speed, wide universality, multiple scanning modes, simple system structure and low cost. Summary of the invention

[0004] In view of the problems of single scanning mechanism and slow imaging speed in traditional photoacoustic microscopy imaging systems, the present invention aims to provide a multi-channel photoacoustic microscopy imaging method and device.

[0005] The objective of the present invention is achieved through the following technical solutions:

[0006] A multi-channel photoacoustic microscopy imaging device comprises a light source, a beam expander, a digital micromirror array, a first lens, a second lens, a microlens array, a third lens, an objective lens, a sample, a sample motion stage, an ultrasonic point detector and a data acquisition card, which are sequentially connected in the direction of light path propagation; wherein the light source emits a pulse laser which is incident on the digital micromirror array after beam expansion by the beam expander to form reflected light, and the pulse laser after beam expansion can irradiate a large area onto the micro-reflectors in the digital micromirror array; the reflected light is projected onto the microlens array after passing through the first lens and the second lens to form a multi-channel laser dot matrix, and then passes through the third lens and the objective lens to form an image on the sample surface and excite to generate an ultrasonic signal, and the ultrasonic signal is received and amplified by the ultrasonic point detector; the data acquisition card is used to store the data amplified by the ultrasonic point detector and reconstruct the target pattern of the sample; wherein the sample is placed on the sample motion stage.

[0007] Furthermore, the light source is a nanosecond pulse laser; when the target tissue receives pulse laser irradiation, the chromophores in the tissue absorb the pulse light energy and undergo non-radiative transitions, the tissue temperature rises instantaneously to produce thermoelastic expansion, and then propagates outward in the form of ultrasound (ie, PA signal).

[0008] Furthermore, the first lens and the second lens form a group of lenses with equal focal lengths, which are used to project the reflected light on the digital micromirror array onto the microlens array in a 1:1 ratio.

[0009] Furthermore, the digital micromirror array is used to reflect the expanded pulsed laser onto the microlens array, and the deflection angle of the reflected light can be adjusted by adjusting the micromirror switch in the digital micromirror array, thereby controlling the pulsed laser incident on the microlens array; wherein the digital micromirror array comprises a plurality of micromirrors of the same size, each of which can be individually adjusted, and each of which has the same deflection angle, and has two forms, "on" and "off", and the deflection angles of the two forms are the same in size and opposite in direction.

[0010] Furthermore, the microlens array includes a plurality of microlenses for forming a focused pulse laser dot matrix at the focal plane position of the microlens of the digital micromirror array to generate a multi-channel excitation light source for exciting the sample tissue to generate an ultrasonic signal.

[0011] The present invention also provides a multi-channel photoacoustic microscopy method, comprising the following steps:

[0012] The light source emits a pulsed laser, which is expanded by a beam expander and incident on a digital micromirror array to form reflected light;

[0013] The reflected light is projected onto a microlens array through a group of lenses with equal focal lengths to form a multi-channel laser dot matrix;

[0014] The multi-channel laser dot array passes through the third lens and the objective lens to form an image on the sample surface and excite to generate an ultrasonic signal. The ultrasonic signal is received and amplified by the ultrasonic point detector to reconstruct the target pattern of the sample.

[0015] Furthermore, the third lens and the objective lens are used to image the pulsed laser dot array formed on the focal plane of the microlens array onto the sample tissue; after the sample tissue is irradiated with the pulsed laser, an ultrasonic signal is generated and propagates outward, and the generated ultrasonic signal is detected and received by the ultrasonic point detector and converted into an electrical signal, which is stored in a data acquisition card, and then the sample target image can be reconstructed after a series of data processing.

[0016] Furthermore, the deflection angle of the digital micromirror is ±12°, and the pulsed laser is incident on the digital micromirror array at an angle of 24° after beam expansion. When a single lens in the digital micromirror array is in an open state (+12°), its emitted light is just perpendicular to the surface of the microlens array after passing through the first lens and the second lens. When a single lens in the digital micromirror array is in a closed state (-12°), its reflected light forms an angle of 48° with the vertical normal, and its reflected light will not enter the first lens and the second lens, so the corresponding microlens on the microlens array cannot receive the incident light, that is, no corresponding focusing spot will be formed at the focus.

[0017] Furthermore, when the incident light passing through the digital micromirror array is all "on" when the micromirrors are all "on", the reflected light will irradiate the surface of the microlens array to form an M*N arranged laser dot matrix, wherein M represents the number of rows of microlenses in the microlens array, and N represents the number of columns of microlenses in the microlens array; wherein the digital micromirror array can correspond to the size of the actual micromirrors and the size of the microlenses, and the n*n micromirrors in the micromirror array form an area that just corresponds to one microlens. When any one of the n*n micro-mirrors in the area of ​​micro-mirrors corresponding to a single micro-lens is turned on, a focused light spot can be formed at the focal plane position of the corresponding micro-lens; when all the micro-mirrors in the area of ​​micro-mirrors corresponding to a single micro-lens are turned on, the focused light spot formed at the focal plane position of the corresponding micro-lens has the strongest energy; when all the micro-mirrors in the area of ​​micro-mirrors corresponding to a single micro-lens are "off", the corresponding micro-lens will not form a laser light spot because it cannot receive incident light; in this way, different numbers of laser dot arrays can be formed at the focal plane of the micro-lens array by controlling the micro-mirror switches in the digital micro-mirror, and the distance and energy of the light spots between the laser dot arrays can be controlled.

[0018] Furthermore, the third lens and the objective lens constitute a 4F system. The laser dot array formed by the microlens array is imaged on the sample surface through the 4F system, exciting the sample to generate an ultrasonic signal. After the ultrasonic signal is detected and amplified by the ultrasonic point detector, a sample target image is reconstructed.

[0019] Furthermore, by controlling the micromirror switches in the digital micromirror array, any excitation light of a point, line array, rectangular array, etc. can be formed at the focal plane of the microlens array to achieve excitation of the sample target tissue. In this way, combined with the sample motion stage, various forms of scanning mechanisms can be realized to achieve rapid scanning photoacoustic microscopy imaging of the sample tissue.

[0020] Furthermore, the ultrasonic point detector is arranged off-axis. According to the different distances from the light sources of the laser dot array on the sample surface to the ultrasonic point detector, the propagation time of the ultrasonic signal generated by each light source to the ultrasonic point detector is different, so that a single ultrasonic detector can simultaneously collect and separate the ultrasonic signals generated by the excitation of multiple channel light sources.

[0021] Furthermore, the sample is arranged on a displacement table with displacement in the X direction, the Y direction and the Z direction, wherein the displacement motion in the X and Y directions is used for scanning and imaging of the sample surface to realize large-area stitching imaging of the sample tissue; the Z direction is used to realize focusing of the laser dot matrix on the sample, so that the optical focus just irradiates the surface position of the object and performs three-dimensional stereoscopic imaging.

[0022] Furthermore, the ultrasonic point detector probe should be arranged in water; the sample is placed in water or the sample surface is in close contact with the liquid, so that the ultrasonic detector can collect the ultrasonic signal generated by the sample tissue being excited by the pulsed laser.

[0023] The beneficial effects of the present invention are:

[0024] The present invention realizes any form of pulse laser array control by combining a micromirror array and a microlens array, and can realize rapid photoacoustic microscopic imaging of sample tissues;

[0025] The present invention can form various forms of pulsed laser combinations such as points, lines, rectangles, etc. at the focal plane of the microlens by controlling the switches of the micromirrors in the micromirror array. Combined with the X-axis motion stage and the Y-axis motion stage in the sample motion stage, various scanning mechanisms for sample tissues can be realized simultaneously. Compared with the existing photoacoustic microscopy imaging system, it has better universality and flexibility;

[0026] In the present invention, the ultrasonic detector is offset arranged to enable a single ultrasonic detector to collect ultrasonic signals generated by multi-channel pulse lasers exciting sample tissues, and the collected signals can be distinguished according to the time difference caused by the different distances between the light sources of each channel and the receiving end of the ultrasonic detector. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0028] Figure 1 is a schematic diagram of the photoacoustic microscopy imaging device of the present invention;

[0029] Figure 2 Schematic diagram of the corresponding relationship between the digital micromirror array and the microlens in the present invention; wherein a is a diagram when the micromirror is in an on state, and b is a diagram when the micromirror is in an off state;

[0030] Figure 3 Schematic diagram of the digital micromirror array debugging spot spacing in the present invention; wherein a is a spot distance of a single microlens spacing diagram, and b is a spot distance of a double microlens spacing diagram;

[0031] Figure 4 It is a schematic diagram of the signal collection of the multi-channel light source and the ultrasonic detector in the present invention;

[0032] Figure 5 It is a schematic diagram of multi-channel light source signal acquisition in the present invention;

[0033] Figure 6 It is a schematic diagram of scanning samples with a multi-channel light source in the present invention.

[0034] Reference numerals:

[0035] 1-light source; 2-beam expander; 3-digital micromirror array; 4-first lens; 5-second lens; 6-microlens array; 7-third lens; 8-objective lens; 9-ultrasonic detector; 10-sample; 11-sample motion stage; 12-data acquisition card. DETAILED DESCRIPTION

[0036] Exemplary embodiments will be described in detail herein, examples of which are shown in the accompanying drawings. When the following description refers to the drawings, the same numbers in different drawings represent the same or similar elements unless otherwise indicated. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present invention. Instead, they are merely examples of devices and methods consistent with some aspects of the present invention as detailed in the appended claims.

[0037] The terms used in the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The singular forms "a", "the" and "the" used in the present invention and the appended claims are also intended to include plural forms unless the context clearly indicates other meanings. It should also be understood that the term "and / or" used herein refers to and includes any or all possible combinations of one or more associated listed items.

[0038] It should be understood that although the terms first, second, third, etc. may be used in the present invention to describe various information, these information should not be limited to these terms. These terms are only used to distinguish the same type of information from each other. For example, without departing from the scope of the present invention, the first information may also be referred to as the second information, and similarly, the second information may also be referred to as the first information. Depending on the context, the word "if" as used herein may be interpreted as "at the time of" or "when" or "in response to determining".

[0039] The present invention is described in detail below in conjunction with the accompanying drawings. In the absence of conflict, the features of the following embodiments and implementations can be combined with each other.

[0040] Embodiment 1:

[0041] See also Figure 1 The present embodiment provides a multi-channel photoacoustic microscopy imaging device, which includes a light source 1, a beam expander 2, a digital micromirror array 3, a first lens 4, a second lens 5, a microlens array 6, a third lens 7, an objective lens 8, an ultrasonic detector 9, a sample 10, a sample motion stage 11 and a data acquisition card 12, etc., arranged in sequence along the optical path. The pulsed laser emitted by the light source 1 forms a multi-channel laser array after passing through the microlens array 6, and finally focuses on the tissue surface of the sample 10 through the objective lens 8, and at the same time excites the sample tissue to generate ultrasonic waves, which are received and converted by the ultrasonic detector 9 to reconstruct the sample target image.

[0042] The light source 1 in the present invention adopts a nanosecond pulse laser, wherein the pulse laser is a 532nm pulse nanosecond laser, the pulse width is 10ns, the repetition frequency is 2KHz, the single pulse energy is ≥1.5mj, and the spot diameter is 2mm; the multiple of the beam expander 2 is 8, the resolution size of the digital micro-mirror is 1920*1080, and the size of the digital micro-mirror is 10.8 The deflection angle of the digital micro-mirror is ±12°; the size of the micro-lens array 6 is 22*22 mm, and the size of a single micro-lens is 140 , the spacing between microlenses is 150 .

[0043] First, the light source 1 emits a pulsed laser, which is converted into parallel light with a diameter of 16 mm after passing through the beam expander 2. The beam spot after beam expansion can irradiate a larger area on the surface of the digital micromirror array 3, which is used to control the number of laser dot arrays formed on the focal plane of the microlens array 6 by controlling the switches of the micromirrors in the digital micromirror array 3.

[0044] The expanded parallel light is incident on the digital micromirror array 3 at an oblique angle of 24°. A set of reflectors can be added between the beam expander 2 and the digital micromirror array 3 to adjust the angle at which the expanded light beam is incident on the digital micromirror array.

[0045] Thus, when the digital micro-mirrors in the digital micro-mirror array 3 are just in the "on" state, since the deflection angle of the digital micro-mirrors is 12°, the emitted light is just as follows: Figure 1 The optical path shown in the figure passes through a group of first lens 4 and second lens 5 with equal focal lengths and is vertically projected onto the surface of microlens array 6, wherein the first lens 4 and the second lens 5 form a 4f system, which projects the reflected light passing through the digital micromirror array 3 onto the front surface of microlens array 6 and forms a pulsed laser dot matrix at the focal plane position of microlens array 6.

[0046] When the digital micro-mirrors in the digital micro-mirror array 3 are in the "off" state, an angle of 48° is generated with the optical axis, and the emitted light will not be collected by the first lens 4 and the second lens 5 below, and no dot light spot will be formed at the lens corresponding to the micro-lens array 6. In this way, the number of pulsed laser dot matrixes formed at the focal plane of the micro-lens array 6 can be adjusted by controlling the micro-mirror switches in the digital micro-mirror array 3.

[0047] Among them, since the focal length of the microlens array is relatively small, a first lens 4 and a second lens 5 with equal focal lengths are used to project the reflected light at the digital micromirror array 3 to the front of the microlens array 6 at a 1:1 ratio. The appropriate lens focal length can be selected according to the actual optical path layout to facilitate the system optical path layout.

[0048] Since the size of a single digital micromirror is 10.8*10.8 , the size of a single microlens is 140 According to the size relationship, it can be calculated that the number of digital micro-mirrors corresponding to a single micro-lens is 12*12. In theory, the reflected light on any digital micro-mirror in the area can form a pulsed laser at the focal plane position of the micro-lens.

[0049] The corresponding relationship between a single microlens and the three regions of the digital micromirror array is as follows: Figure 2As shown, the circle represents a single microlens and the square represents a single digital micromirror. When all the digital micromirrors in the digital micromirror area corresponding to a single microlens are "on", the light spot formed at the focus of the microlens has the maximum power due to the strongest incident light received, as shown in FIG. Figure 2 As shown in Figure a; when all the digital micro-mirrors in the digital micro-mirror area corresponding to a single micro-lens are "off", the micro-lens at the corresponding position does not receive the incident light and does not form a light spot at its focus, as shown in Figure a. Figure 2 As shown in Figure b; when the digital micro-mirror in the area corresponding to the micro-lens is partially "on" and partially "off", a light spot will be formed at the focal position, and the intensity of the light spot will be weak; the intensity of the light spot formed by the micro-lens and whether a light spot is generated can be controlled by controlling the digital micro-mirror switch in the digital micro-mirror area corresponding to the micro-lens.

[0050] After the laser dot array formed by the microlens array passes through a group of 4F systems of the third lens 7 and the objective lens 8, the formed light spot array is just located on the working surface of the objective lens 8 and is focused on the surface of the sample 10. In this way, a multi-channel light source can simultaneously excite the sample 10. The ultrasonic signal generated by the sample 10 when excited by the light source 1 is collected by the ultrasonic detector 9 offset from the main axis of the light source. In this way, since the distances between different light sources 1 and the ultrasonic detector 9 are different, the signal collection time is different, that is, a single ultrasonic detector 9 can simultaneously collect the ultrasonic signals generated by the excitation of multi-channel light sources 1.

[0051] In addition, the sample motion stage 11 is mainly composed of a Z-axis translation stage, a Y-axis translation stage, and an X-axis translation stage. The X- and Y-axis translation stages are used to generate relative movement between the sample 10 and the pulse excitation light source 1 to achieve scanning imaging of the sample area, and the Z-axis translation stage is used to achieve that the pulsed laser is just focused on the target tissue surface of the sample 10, thereby achieving higher optical imaging resolution and being used for three-dimensional stereo imaging.

[0052] Since the attenuation of ultrasonic signals in water is small, the sample 10 and the receiving end of the ultrasonic detector 9 are usually placed in water. When imaging animals or other living specimens, since the sample 10 is not suitable to be placed directly in water, a water tank can be arranged on the upper end of the sample 10. The sample 10 and the water tank are directly isolated by a thin transparent film with a very small thickness. The sample 10 and the water tank are placed on the sample moving table 11, so that the ultrasonic detector 9 can still better receive the ultrasonic signal generated by the sample tissue after being excited by the pulsed laser, thereby better realizing the reconstruction of the sample tissue image.

[0053] Embodiment 2:

[0054] This embodiment is based on the multi-channel microscopic imaging device in Embodiment 1, and provides a device for adjusting the spot spacing between light spot arrays formed at the focal plane of the microlens array by controlling the switches of micro-mirrors in a digital micro-mirror array.

[0055] like Figure 3 As shown in Figure a, when a horizontally arranged light spot array is required, it is only necessary to control the state of the digital micro-mirror in the corresponding area of ​​the micro-lens to be "on". In the figure, the micro-mirrors in the digital micro-mirror array 3 area corresponding to the 7 consecutive micro-lenses are on, and a 7-channel horizontally arranged multi-channel pulsed laser array can be formed at the focal plane of the corresponding lens array to simultaneously excite the sample target tissue.

[0056] Similarly, a longitudinally arranged pulsed laser dot matrix or a rectangular pulsed laser dot matrix can also be generated. This can be achieved by simply controlling the switches of the micro-mirrors in the corresponding digital micro-mirror array 3 region in a longitudinal or rectangular region of the micro-lens array 6. The number of dot matrixes that can be formed here depends on the number of micro-lenses in the micro-lens array 6.

[0057] When it is necessary to adjust the focal plane position of the microlens array 6 to form the distance between adjacent light spots of the pulsed laser dot array, the microlenses in the microlens array 6 are allowed to receive incident light at intervals, and pulsed laser light spots will be formed at the focal planes of the microlenses that receive the incident light, while pulsed laser light spots will not be formed at the focal planes of the microlenses that do not receive the incident light. Figure 3 As shown in Figure a, a spacing of 150 is generated. The light spot array, such as Figure 3 As shown in Figure b, a spacing of 300 is generated. Array of light spots;

[0058] Similarly, light spot arrays with spacings of other sizes can also be generated, where the distance between the light spot arrays is an integer multiple of the spacing between microlenses in the microlens array 6 .

[0059] Embodiment 3:

[0060] This embodiment is based on the multi-channel microscopic imaging device in Embodiment 1, and provides a device that uses a single ultrasonic detector to simultaneously collect ultrasonic signals generated by multi-channel pulse lasers exciting sample tissues.

[0061] like Figure 4 As shown, the 4-channel pulsed laser formed by the digital micromirror array 3 and the microlens array 6 is simultaneously focused on the surface of the sample 10. The distances between the ultrasonic signal generated by each pulsed laser irradiating the sample tissue and the ultrasonic detector 9 are L1, L2, L3, and L4, respectively. Assuming that the propagation speed of sound in water is C, the time for the ultrasonic signal generated by each channel light source 1 to be collected by the ultrasonic detector 9 is , , , Among them, the ultrasonic detector 9 can distinguish that the signal generated by each light source channel is related to the distance u between the light sources. When the distance between adjacent light spots between the light source arrays is too close, the ultrasonic detector 9 cannot distinguish which pulse laser excites the sample tissue to generate the collected ultrasonic signal, and thus cannot effectively reconstruct the sample tissue image. The ultrasonic detector 9 used in this case has a frequency of 20MHz and a bandwidth B of 16MHz, so the spacing between the light spots needs to be greater than , where C is the speed of sound, which is 1500 m / s in water. Calculation shows that the spacing between adjacent multi-channel pulse light sources focused on the sample tissue surface must be greater than or equal to 87.5 Only the ultrasonic detector 9 arranged in an offset manner can accurately distinguish the ultrasonic signals generated by the pulse lasers of each channel exciting the sample 10.

[0062] The microlens parameters in this embodiment are: the microlens spacing is 150 , the microlens size is 140 , the focal length of the objective lens 8 is 45mm, the focal length of the third lens 7 is 50mm, then the corresponding spacing between adjacent light spots is u=135 >87.5 , the ultrasonic signals between adjacent light spots can be collected by the detector. Since the distances between different light spots and the ultrasonic detector 9 are different, the time of signal collection is also different, and the signal will also attenuate with the distance. The acoustic signal collected and processed by the ultrasonic detector 9 is as follows Figure 5 As shown in the figure, the signals between different light spots are shown in the figure. The closer the distance is, the stronger the signal is. In this way, the signals collected by the four light spots can be collected by a single ultrasonic detector 9 at the same time. The collected data is amplified according to the distance compensation and stored in the data acquisition card 12, and then used to reconstruct the sample target image.

[0063] Embodiment 4:

[0064] This embodiment is based on the multi-channel microscopic imaging device in Example 1, and provides a device for performing multi-channel optical microscopic imaging scanning trajectories on samples when the excitation light generated as a rectangular pulse laser array after passing through a microlens array is irradiated onto sample tissue to generate an ultrasonic signal.

[0065] like Figure 6As shown, when the digital micromirror array 3 is controlled to form a rectangular (4x4) laser dot matrix on the focal plane of the microlens array 6, scanning photoacoustic microscopy imaging can be simultaneously performed on a local surface of the sample 10. Theoretically, the speed of photoacoustic microscopy imaging of sample tissue is 16 times faster than that of a single-channel pulsed laser. The imaging speed depends on the number of rectangular laser dot matrices, which can greatly improve the imaging speed compared to traditional photoacoustic microscopy imaging systems.

[0066] By controlling the movement of the X- and Y-axis motion stages in the sample motion stage, planar stitching scanning imaging of the sample tissue can be achieved. Compared with the excitation of the sample by a single-channel or linear array laser light source, the scanning time used for the same sample target tissue is shorter, which can achieve faster photoacoustic microscopy imaging of the sample tissue.

[0067] It is also possible to control the small distance movement of the X and Y axis motion stages in the sample motion stage so that the movement distance is smaller than the spacing of the laser dot array, thereby achieving measurement between array sampling points on the sample and achieving different sampling point densities.

[0068] Those skilled in the art will readily appreciate other embodiments of the present application after considering the description and practicing the contents disclosed herein. The present application is intended to cover any variations, uses or adaptations of the present application, which follow the general principles of the present application and include common knowledge or customary technical means in the art that are not disclosed in the present application. The description and examples are intended to be exemplary only.

[0069] It should be understood that the present application is not limited to the exact construction that has been described above and shown in the drawings, and that various modifications and changes may be made without departing from the scope thereof.

Claims

1. A multi-channel photoacoustic microscopy imaging device, characterized in that: The device comprises a light source, a beam expander, a digital micromirror array, a first lens, a second lens, a microlens array, a third lens, an objective lens, a sample, a sample motion stage, an ultrasonic point detector and a data acquisition card, which are sequentially connected in the direction of light propagation; wherein the light source emits a pulse laser which is incident on the digital micromirror array after being expanded by the beam expander to form reflected light, and the reflected light is projected onto the microlens array after passing through the first lens and the second lens to form a multi-channel laser dot matrix, and then is imaged on the sample surface through the third lens and the objective lens and stimulated to generate an ultrasonic signal, and the ultrasonic signal is received and amplified by the ultrasonic point detector; the data acquisition card is used to store the data amplified by the ultrasonic point detector and reconstruct the target pattern of the sample; wherein the sample is placed on the sample motion stage; After beam expansion, the pulsed laser is incident on the digital micromirror array at an angle of 24°. When a single mirror in the digital micromirror array is in an open state and the deflection angle is +12°, the emitted light is just perpendicular to the incident surface of the microlens array; when a single mirror in the digital micromirror array is in an open state and the deflection angle is -12°, the emitted light has an angle of 48° with the optical axis and will not be incident on the surface of the microlens array; The output light of the digital micromirror array is irradiated onto the surface of the microlens array to form an M*N arranged laser dot matrix, wherein M represents the number of microlens rows in the microlens array, and N represents the number of microlens columns in the microlens array; the digital micromirror array has a 1:1 correspondence between the micromirror size and the microlens size, wherein n*n micromirror regions correspond to one microlens, and the micromirror switch in the micromirror region is adjusted to control whether the corresponding microlens forms a light spot at the focal plane position, thereby controlling the number, spacing, arrangement, and power of the laser dot matrix formed by the microlens array through the switch of the digital micromirror; The ultrasonic point detector is arranged off-axis. According to the different distances from the laser dot array light sources on the sample surface to the ultrasonic point detector, the propagation time of the ultrasonic signal generated by each light source to the ultrasonic point detector is different, so that a single ultrasonic detector can simultaneously collect and separate the ultrasonic signals generated by the excitation of multiple channel light sources.

2. A multi-channel photoacoustic microscopy imaging device according to claim 1, characterized in that: The light source is a nanosecond pulse laser.

3. A multi-channel photoacoustic microscopy imaging device according to claim 1, characterized in that: The first lens and the second lens form a group of lenses with equal focal lengths, and are used to project the reflected light on the digital micromirror array onto the microlens array in a 1:1 ratio.

4. A multi-channel photoacoustic microscopy imaging method, characterized in that: The following steps are involved: The light source emits a pulsed laser, which is expanded by a beam expander and incident on a digital micromirror array to form reflected light; The reflected light is projected onto a microlens array through a group of lenses with equal focal lengths to form a multi-channel laser dot matrix; The multi-channel laser dot array passes through the third lens and the objective lens to form an image on the sample surface and excite to generate an ultrasonic signal, and the ultrasonic signal is received and amplified by the ultrasonic point detector to reconstruct the target pattern of the sample; Wherein, after beam expansion, the pulsed laser is incident on the digital micromirror array at an angle of 24°. When a single mirror in the digital micromirror array is in an open state and the deflection angle is +12°, its reflected light is just perpendicular to the incident surface of the microlens array; when a single mirror in the digital micromirror array is in an open state and the deflection angle is -12°, its reflected light has an angle of 48° with the optical axis and will not be incident on the surface of the microlens array; The digital micromirror array reflects light and irradiates the surface of the microlens array to form an M*N arranged laser dot matrix, wherein M represents the number of microlens rows in the microlens array, and N represents the number of microlens columns in the microlens array; the digital micromirror array has a 1:1 correspondence between the micromirror size and the microlens size, wherein n*n micromirror regions correspond to one microlens, and the micromirror switch in the micromirror region is adjusted to control whether the corresponding microlens forms a light spot at the focal plane position, thereby controlling the number, spacing, arrangement, and power of the laser dot matrix formed by the microlens array through the switch of the digital micromirror; The ultrasonic point detector is arranged off-axis. According to the different distances from the laser dot array light sources on the sample surface to the ultrasonic point detector, the propagation time of the ultrasonic signal generated by each light source to the ultrasonic point detector is different, so that a single ultrasonic detector can simultaneously collect and separate the ultrasonic signals generated by the excitation of multiple channel light sources.

5. A multi-channel photoacoustic microscopy imaging method according to claim 4, characterized in that: The third lens and the objective lens form a 4F system. The laser dot array formed by the microlens array is imaged on the sample surface through the 4F system, exciting the sample to generate an ultrasonic signal. After the ultrasonic signal is detected and amplified by the ultrasonic point detector, a sample target image is reconstructed.

6. A multi-channel photoacoustic microscopy method according to claim 4, characterized in that: The sample is arranged on a displacement table with displacement in X, Y and Z directions, wherein the displacement motion in the X and Y directions is used for scanning and imaging the sample surface, and the Z direction is used for adjusting the light spot to focus on the sample surface and realizing three-dimensional imaging.

7. A multi-channel photoacoustic microscopy method according to claim 4, characterized in that: The ultrasonic point detector probe should be arranged in water; the sample is placed in water or the sample surface is closely attached to the liquid, so that the ultrasonic detector can collect the ultrasonic signal generated by the sample tissue being excited by the pulsed laser.

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