Photoacoustic microscopic imaging system based on multiple view angles

Abstract

The invention belongs to the related technical field of imaging technology, and discloses a multi-view-angle-based photoacoustic microscopic imaging system, which comprises a two-dimensional scanning module, a view angle selection module, a signal detection module and a three-dimensional reconstruction module, and is characterized in that the two-dimensional scanning module enables a light beam to carry out multiple XY plane two-dimensional scanning on a sample; the visual angle selection module adjusts the visual angle of each two-dimensional scanning to enable the angle of each two-dimensional scanning to be different, the visual angle is the direction in which the light beam enters the sample, and the visual angle of each two-dimensional scanning is perpendicular to the signal detection direction; the signal detection module is located on the side face of the sample and receives ultrasonic signals in the detection direction, the detection direction is parallel to the XY plane, and the ultrasonic signals are ultrasonic signals generated by the sample under light beam excitation; and the three-dimensional reconstruction module performs three-dimensional reconstruction according to the ultrasonic signals at different visual angles to obtain a three-dimensional body structure of the sample. According to the system, the axial resolution of photoacoustic microscopy can be improved in a simpler mode, and scanning and three-dimensional reconstruction can be rapidly completed.

Description

Technical Field

[0001] The present invention belongs to the technical field related to imaging technology, and more specifically, relates to a photoacoustic microscopy imaging system based on multiple viewing angles. Background Art

[0002] Photoacoustic microscopy is a label-free imaging technology that can be used for biomedical imaging and is based on the photoacoustic effect and the extensive optical absorption of biological tissues. When biological tissues are irradiated with pulsed lasers, they absorb light transiently and radiate ultrasound waves outward. The ultrasound signals are detected using sensitive ultrasound detection elements (usually the bandwidth of the ultrasound transducer) to achieve tissue imaging. Thanks to the ingenious combination of acoustics and optics, photoacoustic microscopy can adjust its lateral resolution by adjusting the optical scanning device (such as optical focusing), thereby improving its lateral scanning capability, and adjust the axial resolution by adjusting the ultrasound detection element (such as adjusting the bandwidth of the ultrasound transducer), thereby improving its imaging depth capability. However, the current control capability of photoacoustic microscopy is limited, especially in the axial direction. Due to the significant attenuation of high-frequency ultrasound in the sample, the higher the axial resolution of photoacoustic microscopy, the smaller the effective depth range that can be detected.

[0003] There have been some studies to improve axial resolution.

[0004] "Li,Hao,et al."A transparent broadband ultrasonic detector based onan optical micro-ring resonator for photoacoustic microscopy."Scientificreports 4.1(2014):4496." proposed a method to improve axial resolution by using a high-bandwidth ultrasonic detector. However, the ultrasonic detector proposed in this method has a complex manufacturing process, and because high-frequency ultrasonic signals decay rapidly in tissues, a single two-dimensional scan can only obtain limited depth information. Therefore, the axial resolution of this scheme is still insufficient, and its application is limited to optically thin tissues.

[0005] "Sun, Aihui, et al." Multicolor photoacoustic volumetric imaging of subcellular structures." ACS nano 16.2 (2022): 3231-3238." proposed a method to improve the axial resolution by constraining the optical excitation range using a large numerical aperture objective. However, the larger the numerical aperture of the objective, the smaller the distance between it and the sample. Being too close to the sample will affect the maximum imaging depth. In addition, this method can only obtain limited depth information in a single two-dimensional scan, and the axial resolution is still insufficient. If the sample tissue is thick, it is necessary to obtain the depth information of the sample by performing two-dimensional scanning layer by layer, resulting in a slow overall acquisition speed.

[0006] The Chinese patent "CN202410528071.2-A super-resolution photoacoustic microscopy imaging method and device based on structured light illumination" proposes the use of structured light technology to achieve super-resolution photoacoustic imaging through a variety of illumination stripes combined with calculations. However, structured light illumination requires the application of a digital micromirror array as a spatial light modulator, which increases the cost and optical path complexity and reduces the acquisition speed. Summary of the invention

[0007] In view of the above defects or improvement needs of the prior art, the present invention provides a photoacoustic microscopy imaging system based on multi-viewing angles, the purpose of which is to improve the axial resolution of photoacoustic microscopy in a simpler way and quickly complete the scanning.

[0008] To achieve the above object, the present invention provides a photoacoustic microscopy imaging system based on multi-viewing angles, which includes a two-dimensional scanning module, a viewing angle selection module, a signal detection module and a three-dimensional reconstruction module, wherein:

[0009] The two-dimensional scanning module is used to make the light beam perform multiple two-dimensional scans on the sample, and the two-dimensional scanning is moving the scanning track along the XY plane;

[0010] The viewing angle selection module is used to adjust the viewing angle of each two-dimensional scan so that the viewing angle of each two-dimensional scan is different, the viewing angle is the direction in which the light beam is incident on the sample, and the viewing angle of each two-dimensional scan is perpendicular to the detection direction;

[0011] The signal detection module is located on the side of the sample, and is used to receive the ultrasonic signal in the detection direction, the detection direction is parallel to the XY plane, and the ultrasonic signal is the ultrasonic signal generated by the sample under the excitation of the light beam;

[0012] The three-dimensional reconstruction module is used to perform three-dimensional reconstruction according to ultrasound signals at different viewing angles to obtain the three-dimensional structure of the sample.

[0013] Optionally, the two-dimensional scanning module is used to keep the incident light fixed and move the translation stage carrying the sample each time the two-dimensional scanning is performed, so as to achieve two-dimensional scanning of the sample.

[0014] Optionally, the two-dimensional scanning module is used to keep the translation stage carrying the sample fixed and move the incident light each time the two-dimensional scanning is performed, so as to achieve two-dimensional scanning of the sample.

[0015] Optionally, the two-dimensional scanning module includes a scanning galvanometer, and the two-dimensional scanning of the sample is achieved by changing the path of the incident light through the scanning galvanometer.

[0016] Optionally, the two-dimensional scanning module further includes an objective lens located in front of the sample, and the objective lens is used to focus the light beam at the sample to excite the sample to generate the ultrasonic signal.

[0017] Optionally, the viewing angle selection module includes a relay lens and a one-dimensional galvanometer, the relay lens includes lens L1 and lens L2, wherein: the light beam is focused at the one-dimensional galvanometer after passing through the lens L1, and is emitted along a preset direction after direction control by the one-dimensional galvanometer and then enters the lens L2 for beam collimation, and then is focused by the objective lens to obtain a light beam at a corresponding viewing angle.

[0018] Optionally, the signal detection module is an ultrasonic transducer.

[0019] Optionally, the system further comprises a light source for generating a light beam.

[0020] In general, compared with the prior art, the above technical solutions conceived by the present invention have the following advantages:

[0021] 1. The photoacoustic microscopy imaging system provided by the present invention detects ultrasonic signals from the side by placing the signal detection module on the side of the sample and receives ultrasonic signals perpendicular to the scanning light. Since the scanning angle of view is perpendicular to the detection direction, ultrasonic signals excited by the same laser at different depths can be ensured to reach the ultrasonic detection module at the same time. Ultrasonic signals at different depths will be superimposed with phase matching before reaching the ultrasonic detection module, so that the signal received by the ultrasonic detection module is a superposition signal of ultrasonic signals excited at different depths. After two-dimensional scanning at different angles of view, the image at the angle of view can be obtained based on the received superposition signal, and the three-dimensional reconstruction of the internal structure can be achieved based on the images at different angles of view.

[0022] 2. In the present invention, multi-view scanning is innovatively combined with side reception of ultrasonic signals. Compared with the traditional method of receiving ultrasonic signals from the bottom or top of the sample (transmission, reflection), when the sample has a certain thickness, the present invention does not need to use a high-bandwidth ultrasonic detector to improve the axial resolution. The present invention combines multi-view scanning with side reception of ultrasonic signals to achieve deep tissue imaging, and its axial resolution is not limited by the ultrasonic bandwidth, has low requirements for devices, is simpler in equipment, and has lower system cost. Moreover, the present invention does not need to perform axial multi-layer scanning. By changing the viewing angle instead of the traditional dozens of layers of axial scanning, the program speed is improved, making the overall scanning speed faster.

[0023] 3. In the present invention, multi-view scanning is innovatively combined with side reception of ultrasonic signals. Compared with the traditional method using structured light technology, the present invention has a simpler structure, lower cost and faster scanning speed. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 is a structural block diagram of a photoacoustic microscopy imaging system based on multiple viewing angles in one embodiment of the present invention;

[0025] Figure 2 is a schematic structural diagram of a photoacoustic microscopic imaging system that realizes two-dimensional scanning by moving a translation stage in one embodiment of the present invention;

[0026] Figure 3 is a schematic structural diagram of a photoacoustic microscopic imaging system for realizing two-dimensional scanning by deflecting a light beam in one embodiment of the present invention;

[0027] Figure 4 It is a projection diagram of the internal structure of the sample at different viewing angles constructed by receiving the superimposed signal at different viewing angles in one embodiment of the present invention;

[0028] Figure 5 It is a three-dimensional structure of a fiber sample in one embodiment of the present invention. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0030] like Figure 1 The figure shows a structural block diagram of a photoacoustic microscopy imaging system based on multiple viewing angles in one embodiment of the present invention, which includes a two-dimensional scanning module, a viewing angle selection module, a signal detection module and a three-dimensional reconstruction module.

[0031] The two-dimensional scanning module is used to make the light beam perform multiple two-dimensional scans on the sample, and the two-dimensional scanning is to move the scanning track along the XY plane. Figure 1 As shown, the XY plane in the figure is a plane perpendicular to the Z axis.

[0032] The viewing angle selection module is used to adjust the viewing angle of each two-dimensional scan so that the viewing angle of each two-dimensional scan is different. The viewing angle is the direction in which the light beam is incident on the sample. The viewing angle of each two-dimensional scan is perpendicular to the detection direction. The signal detection module is located on the side of the sample and is used to receive the ultrasonic signal in the detection direction. The detection direction is parallel to the XY plane. The ultrasonic signal is the ultrasonic signal generated by the sample under the excitation of the light beam. Figure 1 As shown, the signal detection module is located on the side of the sample, and the detection direction is the X-axis direction in the figure. The X-axis is perpendicular to the Z-axis, and the viewing angle of each scan is perpendicular to the X-axis, that is, the light of each scan is parallel to the YZ plane, and the viewing angle of each two-dimensional scan is different after being adjusted by the viewing angle selection module. Specifically, the signal detection module can select an ultrasonic transducer.

[0033] The three-dimensional reconstruction module is used to perform three-dimensional reconstruction according to ultrasound signals at different viewing angles to obtain the three-dimensional structure of the sample.

[0034] In a specific embodiment, the two-dimensional scanning module can keep the incident light fixed and move the translation stage carrying the sample each time the two-dimensional scanning is performed, so as to achieve two-dimensional scanning of the sample. Figure 2 The figure shows a schematic diagram of the structure of a photoacoustic microscopy imaging system for realizing two-dimensional scanning by moving a translation stage in one embodiment of the present invention. In this embodiment, during each two-dimensional scanning, the optical path remains unchanged, and the sample is moved along the XY plane by controlling the translation stage to move along the XY plane, thereby realizing two-dimensional scanning of the sample.

[0035] In another specific embodiment, the two-dimensional scanning module can also keep the translation stage carrying the sample fixed and move the incident light each time the two-dimensional scanning is performed, so as to achieve two-dimensional scanning of the sample. Figure 3 The figure shows a schematic diagram of the structure of a photoacoustic microscopic imaging system for realizing two-dimensional scanning by deflecting a light beam in an embodiment of the present invention. In this embodiment, the translation stage is stationary, and the light path moves along the XY plane, thereby realizing two-dimensional scanning of the sample. More specifically, the two-dimensional scanning module can use a scanning galvanometer, which changes the path of the incident light through the scanning galvanometer to realize two-dimensional scanning of the sample.

[0036] Specifically, the two-dimensional scanning module further includes an objective lens located in front of the sample, and the objective lens is used to focus the light beam at the sample to excite the sample to generate the ultrasonic signal.

[0037] The viewing angle selection module is used to adjust the viewing angle of each two-dimensional scan so that the light beam is incident on the sample from different directions. Specifically, the viewing angle selection module includes a relay lens and a one-dimensional galvanometer, and the relay lens includes a lens L1 and a lens L2, wherein: the light beam is focused at the one-dimensional galvanometer after passing through the lens L1, and after the direction is controlled by the one-dimensional galvanometer, the light beam is emitted in a preset direction and then enters the lens L2 for beam collimation, and then is focused by the objective lens to obtain a light beam at the corresponding viewing angle. The viewing angle of the current two-dimensional scan is α1. After the current two-dimensional scan is completed, the viewing angle is changed by the viewing angle selection module so that the scanning viewing angle of the next two-dimensional scan is α2, and so on. The scanning viewing angle of each two-dimensional scan is different through the viewing angle selection module.

[0038] When the sample is scanned two-dimensionally, the sample undergoes transient light absorption after being irradiated by the laser and radiates ultrasonic waves outward. The ultrasonic detection module is located on the side of the sample, receives ultrasonic signals from the side, and ensures that the detection direction is perpendicular to the laser direction. This ensures that ultrasonic signals excited by the same laser at different depths reach the ultrasonic detection module at the same time. Ultrasonic signals at different depths will be superimposed in phase matching before reaching the ultrasonic detection module, so that the signal received by the ultrasonic detection module is a superposition signal of ultrasonic signals excited at different depths. Therefore, each time a two-dimensional scan is performed, the ultrasonic detection module will receive a series of superimposed signals at corresponding viewing angles. In the three-dimensional reconstruction module, the superimposed signals are processed to obtain images at different viewing angles, such as Figure 4 FIG. 1 is a projection diagram of the internal structure of a sample at different viewing angles constructed by receiving superimposed signals at different viewing angles in one embodiment of the present invention. In this embodiment, the internal structure is carbon fiber as an example, and the carbon fiber needs to be reconstructed. The multi-view images and the system point spread function are subjected to a three-dimensional deconvolution algorithm to obtain the following: Figure 5 The three-dimensional structure shown can be used to reconstruct the internal structure of the sample.

[0039] The photoacoustic microscopy imaging system provided by the present invention detects ultrasonic signals from the side by placing the signal detection module on the side of the sample, and receives ultrasonic signals perpendicular to the scanning light. Since the scanning angle is perpendicular to the detection direction, it can ensure that ultrasonic signals excited by the same laser at different depths reach the ultrasonic detection module at the same time. Ultrasonic signals at different depths will be superimposed by phase matching before reaching the ultrasonic detection module, so that the signal received by the ultrasonic detection module is a superposition signal of ultrasonic signals excited at different depths. After two-dimensional scanning at different viewing angles, the image at the viewing angle can be obtained based on the received superposition signal, and the three-dimensional reconstruction of the internal structure can be achieved based on the images at different viewing angles. Compared with the traditional method of using a high-bandwidth ultrasonic detector, or performing axial layered scanning, or using structured light to achieve deep tissue imaging, the solution of the present invention has low requirements for devices, simpler equipment, lower system cost, faster overall scanning speed, and higher detection efficiency.

[0040] The technical features of the above-mentioned embodiments can be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification. It should be noted that "in one embodiment", "for example", "for example", etc. of the present invention are intended to illustrate the present invention, rather than to limit the present invention.

[0041] The above-mentioned embodiments only express several implementation methods of the present invention, and the description is relatively specific and detailed, but it cannot be understood as limiting the scope of the patent application. It should be pointed out that for ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention.

Claims

1. A photoacoustic microscopy imaging system based on multiple viewing angles, characterized in that: It includes a two-dimensional scanning module, a viewing angle selection module, a signal detection module and a three-dimensional reconstruction module, among which: The two-dimensional scanning module is used to make the light beam perform multiple two-dimensional scans on the sample, and the two-dimensional scanning is moving the scanning track along the XY plane; The viewing angle selection module is used to adjust the viewing angle of each two-dimensional scan so that the viewing angle of each two-dimensional scan is different, the viewing angle is the direction in which the light beam is incident on the sample, and the viewing angle of each two-dimensional scan is perpendicular to the detection direction; The signal detection module is located on the side of the sample, and is used to receive the ultrasonic signal in the detection direction, the detection direction is parallel to the XY plane, and the ultrasonic signal is the ultrasonic signal generated by the sample under the excitation of the light beam; The three-dimensional reconstruction module is used to perform three-dimensional reconstruction according to ultrasound signals at different viewing angles to obtain the three-dimensional structure of the sample.

2. The multi-view photoacoustic microscopy imaging system according to claim 1, characterized in that: The two-dimensional scanning module is used to keep the incident light fixed and move the translation stage carrying the sample each time the two-dimensional scanning is performed, so as to realize the two-dimensional scanning of the sample.

3. The multi-view photoacoustic microscopy imaging system according to claim 1, characterized in that: The two-dimensional scanning module is used to keep the translation stage carrying the sample fixed and move the incident light each time a two-dimensional scan is performed, thereby realizing a two-dimensional scan of the sample.

4. The multi-viewing photoacoustic microscopy imaging system according to claim 3, characterized in that: The two-dimensional scanning module includes a scanning galvanometer, which changes the path of incident light through the scanning galvanometer to achieve two-dimensional scanning of the sample.

5. The multi-viewing photoacoustic microscopy imaging system according to any one of claims 1, characterized in that: The two-dimensional scanning module further includes an objective lens located in front of the sample, and the objective lens is used to focus the light beam on the sample to excite the sample to generate the ultrasonic signal.

6. The multi-viewing photoacoustic microscopy imaging system according to claim 5, characterized in that: The viewing angle selection module includes a relay lens and a one-dimensional galvanometer, and the relay lens includes a lens L1 and a lens L2, wherein: the light beam is focused at the one-dimensional galvanometer after passing through the lens L1, and is emitted along a preset direction after being direction-controlled by the one-dimensional galvanometer and then enters the lens L2 for beam collimation, and then is focused by the objective lens to obtain a light beam at a corresponding viewing angle.

7. The multi-viewing photoacoustic microscopy imaging system according to claim 1, characterized in that: The signal detection module is an ultrasonic transducer.

8. The multi-viewing photoacoustic microscopy imaging system according to claim 1, characterized in that: The system further comprises a light source for generating a light beam.

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