A biological tissue polarization imaging forward-backward scattering detection system and method capable of adjusting tissue fluid thickness

Abstract

This invention discloses a biological tissue polarization imaging forward and backward scattering detection system and method with adjustable tissue fluid thickness, belonging to the field of biomedical optical imaging detection systems and methods. It solves the problems of existing technologies for detecting the polarization characteristics of biological tissue in simulated tissue fluid, such as the uniform thickness of the simulated tissue fluid, insufficient synchronicity of time-division acquisition of polarization images, and difficulty in obtaining thickness-responsive polarization features. This invention changes the thickness of the simulated tissue fluid by adjusting the displacement of the first and second movable inner walls. The incident light in a polarized state passes through the biological tissue sample to obtain forward and backward scattering signals, which are decomposed into multiple polarization directions to generate corresponding scattering images. Polarization image reconstruction and feature analysis enable simultaneous acquisition of forward and backward scattering polarization information under the same tissue fluid thickness, improving the consistency and accuracy of biological tissue polarization scattering feature detection.

Description

Technical Field

[0001] This invention relates to a biomedical optical imaging detection system and method, specifically to a biological tissue polarization imaging backscattering detection system and method with adjustable tissue fluid thickness. Background Technology

[0002] When biological tissues are exposed to light, changes in absorption, scattering, and polarization occur due to factors such as internal cell structure, cell nucleus morphology, collagen fiber arrangement, water content, lipid composition, and the distribution of scattering particles. Compared to traditional intensity imaging, polarization imaging can reflect tissue microstructure, anisotropic distribution, and the modulation of polarization state by the scattering medium. Therefore, polarization imaging has significant application value in biological tissue identification, lesion tissue analysis, tumor tissue detection, and assessment of changes in tissue microstructure.

[0003] In real biological environments, biological tissues are typically not completely exposed but coexist with tissue fluid, extracellular fluid, cerebrospinal fluid, or other biological fluid media. Therefore, biological tissues are usually placed in simulated tissue fluid for polarization imaging and analysis. The thickness, refractive index, scattering coefficient, and absorption characteristics of the simulated tissue fluid affect the propagation path, scattering intensity, and polarization retention of light within the simulated tissue fluid surrounding the biological tissue. Therefore, when detecting the polarization characteristics of biological tissues, it is necessary to simulate the optical environment under different simulated tissue fluid thicknesses as much as possible to improve the correspondence between the detection results and the real biological tissue environment.

[0004] Existing biological tissue polarization characteristic detection devices mostly focus on single-direction transmission imaging, reflection imaging, or scattering imaging, which typically makes it difficult to simultaneously acquire forward scattering and backscattering information under the same simulated tissue fluid conditions. When forward scattering and backscattering detection are performed separately, conditions such as sample state, simulated tissue fluid thickness, light source stability, and acquisition time may change, easily leading to a lack of strict correspondence between forward and backscattering results, thus affecting the accuracy of polarization characteristic analysis.

[0005] Furthermore, existing liquid tank structures used to simulate tissue fluid environments typically have a fixed thickness, or can only change the thickness of the simulated tissue fluid in a single direction. When the movable inner wall is only located on one side, the adjustment process may only change the path length of forward-scattered light or part of the scattered light through the simulated tissue fluid, without ensuring that the effective optical path lengths of the incident light, forward-scattered light, and back-scattered light change synchronously through the simulated tissue fluid. Consequently, the obtained forward and backward scattering polarization data may simultaneously include the effects of scattering differences inherent in biological tissue and differences in liquid optical path length, reducing the comparability of forward and backward polarization characteristic results.

[0006] In an adjustable liquid tank structure, changing the volume of the liquid space by moving the inner wall may cause changes in the level of the simulated tissue fluid. These changes in level will further alter the path of backscattered or oblique scattered light through the simulated tissue fluid, thus introducing non-target variables. Simultaneously, biological tissues may drift, tilt, or deform in the simulated tissue fluid. This is especially true for isolated soft tissue, nerve tissue, or tumor tissue samples, where changes in the position and orientation of the biological tissue directly affect the distribution of the scattered light field and the results of polarization feature reconstruction.

[0007] On the other hand, existing polarization imaging devices often use a rotating analyzer to acquire images at multiple polarization angles in a time-division manner. Although this method can obtain images with different polarization directions, in cases where there is simulated tissue fluid disturbance, slight biological tissue drift, or fluctuations in light source power, time-division acquisition will lead to time errors between images with different polarization directions, thus affecting the reconstruction accuracy of polarization features such as Stokes parameters, degree of linear polarization, and polarization angle.

[0008] Furthermore, existing detection methods often focus on polarization images or scattering intensity characteristics under a single simulated tissue fluid thickness condition, lacking continuous characterization of the changes in forward and backward polarization scattering characteristics under different simulated tissue fluid thickness conditions. For different samples such as normal biological tissue, diseased biological tissue, tumor biological tissue, or neural biological tissue, the response trend of polarization characteristics to changes in simulated tissue fluid thickness may differ. If thickness-responsive polarization characteristics cannot be constructed, it is difficult to fully utilize the additional information provided by changes in the simulated tissue fluid environment for the identification of biological tissue microstructures.

[0009] Therefore, it is necessary to provide a biological tissue forward and backward scattering polarization characteristic detection system and method that can achieve the same or comparable equivalent optical path lengths for the forward and backward scattering directions within the simulated tissue fluid while keeping the liquid level and sample state stable, enabling snapshot-style polarization synchronous acquisition, and extracting thickness-responsive polarization characteristics. Summary of the Invention

[0010] The purpose of this invention is to address the problems in the prior art of detecting the polarization characteristics of biological tissues in simulated tissue fluid, such as the uniform thickness of the simulated tissue fluid, insufficient synchronization of time-division acquisition of polarization images, and difficulty in obtaining thickness-responsive polarization features. The invention provides a biological tissue polarization imaging backscattering detection system and method with adjustable tissue fluid thickness.

[0011] To achieve the above objectives, the technical solution provided by this invention is as follows:

[0012] A biological tissue polarization imaging backscattering detection system with adjustable tissue fluid thickness is characterized by including: an incident light generator with polarization state, a variable thickness liquid tank, a first movable inner wall, a second movable inner wall, a forward scattering detector, a backscattering detector, a feature extraction module, a control system, two transparent optical windows, a displacement driving mechanism, and a sample positioning structure.

[0013] The two transparent optical windows are respectively disposed on two opposite side walls of the variable thickness liquid tank. The first movable inner wall and the second movable inner wall are disposed in the variable thickness liquid tank and located between the two transparent optical windows. The two windows and the inner wall of the variable thickness liquid tank form a liquid cavity for holding simulated tissue fluid. The working end of the displacement driving mechanism passes through the variable thickness liquid tank and is connected to the first movable inner wall and the second movable inner wall respectively. It is used to drive the first movable inner wall and the second movable inner wall to move synchronously or differentially, so as to change the thickness of the simulated tissue fluid or the equivalent optical path inside.

[0014] The sample positioning structure is set inside the variable thickness liquid tank and located between the first movable inner wall and the second movable inner wall, and is used to fix the biological tissue sample to be tested.

[0015] The polarized incident light generating device is positioned opposite one of the transparent optical windows to emit polarized incident light, which then illuminates the biological tissue sample to be tested through the transparent optical window to form forward polarization scattering signal and back polarization scattering signal.

[0016] The forward scattering detector is positioned in the forward scattering direction where the forward polarization scattering signal is located, and is used to acquire the forward polarization scattering signal and generate forward scattering images in multiple polarization directions;

[0017] The backscattering detector is positioned in the backscattering direction where the back polarization scattering signal is located, and is used to acquire the back polarization scattering signal and generate backscattering images in multiple polarization directions.

[0018] The control system is connected to the incident light generator in polarization state, the displacement driving mechanism, the feature extraction module, the forward scattering detector, and the backscattering detector, respectively, and is used to send control commands, perform data transmission, and associate and store data.

[0019] The feature extraction module is connected to the forward scattering detector and the backscattering detector, respectively, and is used to preprocess, reconstruct polarization images and correct equivalent optical paths of forward scattering images and backscattering images in multiple polarization directions. Based on the correction results, the polarization features of the reconstructed polarization images are calculated and the thickness response curve of the simulated tissue fluid is plotted.

[0020] Furthermore, it also includes a liquid level maintaining unit;

[0021] The liquid level maintaining unit is connected to the control system and is connected to the liquid chamber area through a pipeline. It is used to detect the liquid level change of the simulated tissue fluid in the variable thickness liquid tank and maintain the liquid level of the simulated tissue fluid at a constant level or within a preset liquid level range during the synchronous or differential movement of the first movable inner wall and the second movable inner wall.

[0022] Furthermore, the liquid level maintaining unit includes a liquid level sensor and a liquid level compensation mechanism;

[0023] The liquid level sensor is installed on the variable thickness liquid tank and located inside the liquid cavity, and is used to detect changes in the liquid level of the simulated tissue fluid in the variable thickness liquid tank.

[0024] The liquid level compensation mechanism includes one or more of the following: a replenishment mechanism, a drainage mechanism, an overflow tank, a liquid storage compensation chamber, or a closed compensation chamber. It is used to replenish or drain simulated tissue fluid into a variable thickness liquid tank according to the detection results of the liquid level sensor, so that the liquid level of the simulated tissue fluid is constant or within a preset liquid level range.

[0025] Furthermore, the forward scattering detector includes a first micro-polarization array / polarization beam splitter and a first sCMOS detector; the first micro-polarization array / polarization beam splitter is disposed in the forward scattering direction where the forward polarization scattering signal is located, and is used to decompose the forward polarization scattering signal into forward light signals with multiple polarization directions; the first sCMOS detector is disposed opposite to the first micro-polarization array / polarization beam splitter, and is used to acquire forward light signals with multiple polarization directions and generate forward scattering images with multiple polarization directions;

[0026] The backscattering detector includes a second micro-polarization array / polarization beam splitter and a second sCMOS detector; the second micro-polarization array / polarization beam splitter is disposed in the backscattering direction where the backscattered polarization signal is located, and is used to decompose the backscattered polarization signal into backscattered light signals in multiple polarization directions; the second sCMOS detector is disposed opposite to the second micro-polarization array / polarization beam splitter, and is used to acquire backscattered light signals in multiple polarization directions and generate backscattered images in multiple polarization directions;

[0027] Both the first sCMOS detector and the second sCMOS detector are connected to the control system and the feature extraction module. The control system synchronously triggers the first sCMOS detector and the second sCMOS detector to acquire forward scattering images and backscattering images in multiple polarization directions, and sends them to the feature extraction module.

[0028] The first micro-polarization array / polarization beam splitter and the second micro-polarization array / polarization beam splitter are both one or a combination of two of the following: a focal plane micro-polarization array, a multi-channel polarization beam splitter, a polarization beam splitter, or a snapshot Stokes imaging component.

[0029] Furthermore, the transparent optical window, the first movable inner wall, and the second movable inner wall are all made of quartz glass, optical glass, sapphire glass, or transparent polymer optical materials.

[0030] Furthermore, the incident light generating device in the polarization state includes a laser, a collimation system, and a polarizer arranged sequentially along the optical axis;

[0031] The polarizer is positioned opposite one of the transparent optical windows;

[0032] The laser is connected to the control system.

[0033] Furthermore, the control commands include a start control command for the incident light generating device in a polarization state, a synchronous trigger command for the forward scattering detector and the backscattering detector, a control command for the liquid level maintaining unit to replenish or discharge simulated tissue fluid into the liquid chamber, and a drive command for the displacement driving mechanism to synchronously or differentially move the first movable inner wall and the second movable inner wall.

[0034] The data transmission includes receiving liquid level change information output by the liquid level maintenance unit, the displacement of the first movable inner wall and the second movable inner wall when acquiring forward scattering and backscattering images each time, and the thickness of the simulated tissue fluid.

[0035] The data association and storage includes recording detection state parameters and associating and storing these parameters with polarization features. The detection state parameters include the displacement of the first and second movable inner walls during each acquisition of forward-scattered and backscattered images, the liquid level of the simulated tissue fluid, the thickness of the simulated tissue fluid, and the equivalent optical path length of the forward-scattering direction within the simulated tissue fluid. The equivalent optical path length of the backscattering direction in the simulated tissue fluid Forward scattering direction optical thickness Backscattering direction optical thickness The time for acquiring forward polarization scattering and back polarization scattering signals, the direction of forward polarization scattering and back polarization scattering signals, and the polarization direction of the forward scattering and back scattering images;

[0036] The polarization characteristics include Stokes parameters, degree of linear polarization, polarization angle, ratio of forward and backward scattering intensity, or polarization difference characteristics.

[0037] A method for detecting backscattering and forward scattering in biological tissue polarization imaging with adjustable tissue fluid thickness, characterized by employing the aforementioned system for detecting backscattering and forward scattering in biological tissue polarization imaging with adjustable tissue fluid thickness, comprising the following steps:

[0038] S1. Fix the biological tissue sample to be tested onto the sample positioning structure, and add simulated tissue fluid into the liquid cavity to the preset height;

[0039] S2. The control system controls the displacement drive mechanism to drive the first movable inner wall and the second movable inner wall to move synchronously or differentially to the preset thickness h of the simulated tissue fluid, and makes the equivalent optical path of the forward scattering direction and the back scattering direction in the simulated tissue fluid satisfy the preset relationship.

[0040] S3. The polarized incident light generator is activated by the control system to emit polarized incident light; at the same time, the forward scattering detector and the backscattering detector are synchronously triggered to acquire forward scattering images and backscattering images of multiple polarization directions within the same triggering period, and output to the feature extraction module.

[0041] S4. The feature extraction module performs preprocessing, polarization image reconstruction, and equivalent optical path correction on forward scattering images and backscattering images in multiple polarization directions, and calculates the polarization features of the reconstructed polarization image based on the correction results.

[0042] S5. Change the preset thickness h of the simulated tissue fluid, repeat S2-S4, and obtain the polarization features of the reconstructed polarization images corresponding to the thickness of multiple simulated tissue fluids. Plot the thickness response curve of the polarization features as the thickness of the simulated tissue fluid changes, and extract the thickness attenuation coefficient, polarization retention capability index or tissue recognition features based on the thickness response curve.

[0043] Furthermore, S2 specifically refers to:

[0044] S21. The control system controls the displacement drive mechanism to drive the first movable inner wall and the second movable inner wall to move differentially to the preset thickness h of the simulated tissue fluid;

[0045] S22, Preset equivalent optical path error threshold Calculate the equivalent optical path length of the forward scattering direction in the simulated tissue fluid. The equivalent optical path length of the backscattering direction in the simulated tissue fluid Determine whether it satisfies ;

[0046] If so, the equivalent optical path lengths of the forward scattering direction and the backscattering direction in the simulated tissue fluid satisfy the preset relationship, and S23 is executed; otherwise, the first movable inner wall and the second movable inner wall are driven to move synchronously, and S22 is returned.

[0047] S23. The control system controls the liquid level holding unit to maintain the liquid level of the simulated tissue fluid at a constant level or within a preset liquid level range.

[0048] Furthermore, S4 specifically refers to:

[0049] S41. Preprocess the forward scattering images and backscattering images of multiple polarization directions respectively, including background subtraction, dark field correction, flat field correction, image registration, light intensity normalization, equivalent optical path correction and fixed Mueller matrix correction in sequence.

[0050] S42. Reconstruct the forward scattering images with multiple polarization directions after preprocessing to obtain the reconstructed forward scattering image; reconstruct the backscattering images with multiple polarization directions after preprocessing to obtain the reconstructed backscattering image.

[0051] S43. Calculate the correction parameters based on the equivalent optical path difference between the forward scattering direction and the backscattering direction in the simulated tissue fluid;

[0052] S44. Perform equivalent optical path correction on the reconstructed forward scattering image and the reconstructed backscattering image respectively, based on the correction parameters.

[0053] S45. Calculate the Stokes parameters, linear polarization degree, and polarization angle of the reconstructed forward scattering image and the reconstructed backscattering image after equivalent optical path correction, and calculate the ratio of forward and backward scattering intensities or polarization difference characteristics.

[0054] Compared with the prior art, the present invention has the following beneficial technical effects:

[0055] 1. The present invention provides a biological tissue polarization imaging backscattering detection system with adjustable tissue fluid thickness. By synchronously or differentially moving the first movable inner wall and the second movable inner wall, it can not only change the thickness of the simulated tissue fluid, but also make the equivalent optical path of the forward scattering direction and the backscattering direction in the simulated tissue fluid meet the preset relationship, thereby improving the comparability of the forward and backward polarization characteristics.

[0056] 2. The present invention provides a biological tissue polarization imaging forward and backward scattering detection system with adjustable tissue fluid thickness. By maintaining the liquid level height of the simulated tissue fluid during the movement of the first and second movable inner walls through a liquid level holding unit, the system can avoid unexpected changes in the effective optical path of the forward and backward scattering directions caused by changes in liquid level height, thereby improving the consistency of detection results.

[0057] 3. The present invention provides a biological tissue polarization imaging backscattering detection system with adjustable tissue fluid thickness. By maintaining the position and orientation of the biological tissue sample to be tested through the sample positioning structure, it can reduce the influence of the drift, tilt or deformation of the biological tissue sample on the scattered light field and polarization characteristics, and improve the repeatability of the detected polarization characteristics under different simulated tissue fluid thickness conditions.

[0058] 4. The present invention provides a biological tissue polarization imaging forward and backward scattering detection system with adjustable tissue fluid thickness. Both the forward scattering detector and the backward scattering detector include a micro-polarization array / polarization beam splitter component and an sCMOS detector. It can realize snapshot-type polarization synchronous acquisition and obtain scattering images of multiple polarization directions in one exposure or the same synchronous triggering cycle, thereby reducing the time error caused by time-division acquisition by rotating analyzer.

[0059] 5. The present invention provides a biological tissue polarization imaging forward and backward scattering detection method with adjustable tissue fluid thickness. It constructs thickness response curves under different simulated tissue fluid thickness conditions. It can not only obtain reconstructed forward scattering images and reconstructed backward scattering images under a single thickness, but also extract thickness-response polarization features that reflect the coupling change law between biological tissue microstructure and simulated tissue fluid, thereby improving the ability of biological tissue identification and lesion analysis. Attached Figure Description

[0060] Figure 1 This is a schematic diagram of an embodiment of a biological tissue polarization imaging forward and backward scattering detection system with adjustable tissue fluid thickness provided by the present invention.

[0061] Figure 2 This is a schematic diagram showing the connection between the variable thickness liquid tank, the displacement driving mechanism, and the liquid level holding unit in an embodiment of the present invention;

[0062] Figure 3 This is a schematic diagram illustrating the control system sending control commands, data transmission, and data association and storage in an embodiment of the present invention;

[0063] Figure 4 This is a schematic flowchart of an embodiment of a biological tissue polarization imaging backscattering detection method with adjustable tissue fluid thickness according to the present invention.

[0064] Figure 5 This is a schematic diagram of the workflow of the feature extraction module in this invention;

[0065] Figure 6 This is a schematic diagram of the thickness response curve of linear polarization degree as a function of simulated tissue fluid thickness obtained in an embodiment of the present invention.

[0066] Figure label:

[0067] 1-Laser; 2-Collimation system; 3-Polarizer; 4-First movable inner wall; 5-Biological tissue sample to be tested; 6-Variable thickness liquid tank; 7-Second movable inner wall; 8-Forward scattering detector; 81-First micro-polarization array / polarization beam splitter assembly; 82-First sCMOS detector; 9-Backscattering detector; 91-Second micro-polarization array / polarization beam splitter assembly; 92-Second sCMOS detector; 10-Sample positioning structure; 11-Liquid level maintenance unit; 12-Feature extraction module; 13-Control system; 14-Simulated tissue fluid; 15-Transparent optical window; 16-Displacement drive mechanism. Detailed Implementation

[0068] To make the objectives, advantages, and features of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. Those skilled in the art should understand that these embodiments are merely used to explain the technical principles of the present invention and are not intended to limit the scope of protection of the present invention.

[0069] In this embodiment, the simulated tissue fluid 14 used is one of physiological saline, artificial cerebrospinal fluid, tissue equivalent scattering fluid, lipid-containing scattering fluid, liquid containing scattering particles, or a combination thereof.

[0070] The biological tissue sample 5 to be tested includes one of the following: in vitro normal tissue sample, diseased tissue sample, tumor tissue sample, nerve tissue sample, neurotumor tissue sample, or artificial tissue model.

[0071] This embodiment provides a biological tissue polarization imaging backscattering detection system with adjustable tissue fluid thickness, such as... Figure 1 As shown, the device includes a polarized incident light generator, a first movable inner wall 4, a variable thickness liquid tank 6, a second movable inner wall 7, a forward scattering detector 8, a backscattering detector 9, a sample positioning structure 10, a liquid level maintaining unit 11, a feature extraction module 12, a control system 13, two transparent optical windows 15, and a displacement driving mechanism 16. The polarized incident light generator includes a laser 1, a collimation system 2, and a polarizer 3.

[0072] In this embodiment, laser 1 is connected to control system 13. Control system 13 issues a start control command to control laser 1 to emit a detection beam. Laser 1 can be a semiconductor laser, solid-state laser, helium-neon laser, continuous laser, pulsed laser, or other stable output light source. Depending on the detection requirements, laser 1 can use a single wavelength light source or multiple wavelength light sources to obtain polarization scattering characteristics under different wavelength conditions.

[0073] Collimation system 2 is positioned in the optical path of the detection beam to collimate the detection beam, forming a collimated beam with good directionality. Collimation system 2 can employ one or more of the following: collimating lens group, beam expander and collimator assembly, aperture stop, or spatial filter assembly.

[0074] The polarizer 3 is positioned after the collimation system 2 to modulate the detection beam into incident light with a preset polarization state. The preset polarization state can be linear polarization, circular polarization, elliptical polarization, or other known polarization states. In this embodiment, the polarizer 3 uses a linear polarizer to form linearly polarized light in a preset direction. The polarizer 3 is positioned opposite one of the transparent optical windows 15.

[0075] Two transparent optical windows 15 are respectively disposed on two opposite side walls of the variable thickness liquid tank 6. A first movable inner wall 4 and a second movable inner wall 7 are disposed within the variable thickness liquid tank 6, located between the two transparent optical windows 15. These two walls, together with the inner wall of the variable thickness liquid tank 6, form a liquid cavity through which simulated tissue fluid 14 is contained. The control end of the displacement drive mechanism 16 is connected to the control system 13. The working end of the displacement drive mechanism 16 passes through the variable thickness liquid tank 6 and is connected to the first movable inner wall 4 and the second movable inner wall 7, respectively, to drive the first movable inner wall 4 and the second movable inner wall 7 to move synchronously or differentially, thereby changing the thickness of the simulated tissue fluid 14 (i.e., the distance between the first movable inner wall 4 and the second movable inner wall 7) or its equivalent optical path length. Specifically:

[0076] The control system 13 issues differential movement drive commands to the first movable inner wall 4 and the second movable inner wall 7, and the displacement drive mechanism 16 drives the first movable inner wall 4 and the second movable inner wall 7 to move differentially, so as to change the thickness of the simulated tissue fluid 14; the control system 13 issues synchronous movement drive commands to the first movable inner wall 4 and the second movable inner wall 7, and the displacement drive mechanism 16 drives the first movable inner wall 4 and the second movable inner wall 7 to move synchronously, so as to change the equivalent optical path within the simulated tissue fluid 14.

[0077] In this embodiment, synchronous movement means that the first movable inner wall 4 and the second movable inner wall 7 move at the same displacement or at the same speed; differential movement means that the first movable inner wall 4 and the second movable inner wall 7 move according to a preset displacement ratio or different displacement amounts.

[0078] To improve the comparability between forward-scattered polarization signals and back-scattered polarization signals, this embodiment can use the control system 13 to perform equivalent optical path consistency control on the movement process of the first movable inner wall 4 and the second movable inner wall 7, as detailed below:

[0079] Let the scattering direction d include the forward scattering direction F and the backscattering direction B, that is:

[0080] .

[0081] The refractive index of simulated tissue fluid 14 is Thickness is The geometric propagation distance of the simulated tissue fluid 14 corresponding to the scattering direction d is: The equivalent optical path length in this direction within the simulated tissue fluid 14 is... Represented as:

[0082] .

[0083] When further considering the absorption and scattering attenuation of the simulated tissue fluid 14, the optical thickness in the scattering direction d... Represented as:

[0084] ;

[0085] in:

[0086] ;

[0087] To simulate the absorption coefficient of tissue fluid 14, To simulate the scattering coefficient of tissue fluid 14, The total attenuation coefficient is used to simulate tissue fluid 14.

[0088] The control system 13 obtains the equivalent optical path length of the forward scattering direction within the simulated tissue fluid 14 based on geometric parameters such as the displacement of the first movable inner wall 4 and the second movable inner wall 7, the position of the biological tissue sample 5 to be tested, the liquid level of the simulated tissue fluid 14, the detection angle of the forward scattering detector 8, the detection angle of the backscattering detector 9, and the variable thickness liquid tank 6. The equivalent optical path length of the backscattering direction within the simulated tissue fluid 14 .

[0089] The control system 13 controls the first movable inner wall 4 and the second movable inner wall 7 to move synchronously or differentially, so that the equivalent optical path lengths of the forward scattering direction and the backward scattering direction in the simulated tissue fluid 14 meet a preset relationship, that is, the equivalent optical path lengths are consistent.

[0090] ;

[0091] in, This is the preset equivalent optical path error threshold.

[0092] Alternatively, control system 13 can also adjust the optical thickness in the forward scattering direction. and optical thickness in the backscattering direction satisfy:

[0093] ;

[0094] in, This is the preset optical thickness error threshold.

[0095] By using the above equivalent optical path consistency condition, the problem of incomparable forward and backward polarization characteristics caused by only changing the geometric thickness of simulated tissue fluid in one direction can be avoided, so that forward and backward polarization characteristics can be obtained under the same or comparable simulated tissue fluid optical environment.

[0096] The transparent optical window 15 is used to transmit incident light in a polarized state and illuminate the biological tissue sample 5 to be tested to form forward polarization scattering signal and back polarization scattering signal. The forward polarization scattering signal and back polarization scattering signal are output through two transparent optical windows 15. The transparent optical window 15 is made of quartz glass, optical glass, sapphire glass or transparent polymer optical material, and is used to reduce the absorption, scattering and polarization state interference of the window material on the incident light, forward scattered light or back scattered light.

[0097] The forward scattering detector 8 includes a first micro-polarization array / polarization beam splitter 81 and a first sCMOS detector 82. The first micro-polarization array / polarization beam splitter 81 is disposed in the forward scattering direction where the forward polarization scattering signal is located, and is used to decompose the forward polarization scattering signal into forward light signals with multiple polarization directions. The first sCMOS detector 82 is disposed opposite to the first micro-polarization array / polarization beam splitter 81, and is used to acquire forward light signals with multiple polarization directions and generate forward scattering images with multiple polarization directions.

[0098] The backscattering detector 9 includes a second micro-polarization array / polarization beam splitter 91 and a second sCMOS detector 92. The second micro-polarization array / polarization beam splitter 91 is disposed in the backscattering direction where the backscattered polarization signal is located, and is used to decompose the backscattered polarization signal into backscattered light signals in multiple polarization directions. The second sCMOS detector 92 is disposed opposite to the second micro-polarization array / polarization beam splitter 91, and is used to acquire backscattered light signals in multiple polarization directions and generate backscattered images in multiple polarization directions.

[0099] The first micro-polarization array / polarization beam splitter 81 and the second micro-polarization array / polarization beam splitter 91 are both one or a combination of two of the following: a focal plane micro-polarization array, a multi-channel polarization beam splitter, a polarization beam splitter assembly, or a snapshot Stokes imaging assembly. This allows the forward scattering detector 8 and the backscattering detector 9 to acquire forward and backscattering images in at least two polarization directions within a single exposure or the same synchronous triggering cycle, such as polarization images at 0°, 45°, 90°, and 135°. The first sCMOS detector 82 and the second sCMOS detector 92 receive image information from the aforementioned multiple polarization directions within the same exposure cycle, thereby achieving snapshot-type polarization synchronous acquisition. Both the first sCMOS detector 82 and the second sCMOS detector 92 are connected to the control system 13 and the feature extraction module 12. The synchronous trigger command issued by the control system 13 synchronously triggers the first sCMOS detector 82 and the second sCMOS detector 92 to acquire forward scattering images and backscattering images in multiple polarization directions, and sends them to the feature extraction module 12. Compared with the time-division acquisition method of the rotating analyzer, the snapshot polarization synchronous acquisition can reduce the time error between images in different polarization directions and reduce the impact of liquid disturbance, slight sample drift, light source fluctuation or mechanical vibration on the polarization feature reconstruction results.

[0100] Suppose that the image acquired when the polarization direction is detected is θ under the scattering direction d is... The value of θ ranges from 0°, 45°, 90° and 135°.

[0101] When using images with four polarization directions: 0°, 45°, 90°, and 135° , , , When reconstructing linear polarization features, we can obtain:

[0102] ;

[0103] in, , and These are the Stokes parameters under the conditions of scattering direction d and simulated tissue fluid thickness h, respectively.

[0104] Since the transparent optical window 15 is fixedly positioned at the optical path passage location of the variable thickness liquid tank 6, its material, thickness, and installation angle remain unchanged during the detection process. Therefore, the influence of the transparent optical window 15 on the polarization state can be expressed as a fixed Mueller matrix. By introducing a fixed Mueller matrix correction, the fixed deviation of the transparent optical window 15 on the polarization measurement results can be reduced.

[0105] Let the Mueller matrix of the transparent optical window corresponding to the scattering direction d be... The system response matrix of the sCMOS detector and the micro-polarization array / polarization beam splitter is: The equivalent scattering Mueller matrix of the biological tissue sample 5 under scattering direction d is: The equivalent Mueller matrix for simulating tissue fluid thickness h is: The Stokes vector of the incident light in polarized state is The original Stokes vector obtained under the scattering direction d Represented as:

[0106] ;

[0107] in, The matrix is ​​fixed and does not change with the thickness h of the simulated tissue fluid 14; the matrix that changes with the thickness h of the simulated tissue fluid 14 is mainly the equivalent Mueller matrix. And its corresponding scattering, absorption and depolarization.

[0108] For ease of expression, the combined polarization effect of the scattering direction d through the transparent optical window 15 can be represented as... When the effect of the transparent optical window 15 at the incident end on the polarized incident light needs to be considered separately, the Mueller matrix of the transparent optical window 15 can also be incorporated into the system calibration state of the polarized incident light.

[0109] To eliminate the fixed influence of the transparent optical window 15 and the sCMOS detector response on the polarization detection results, the Mueller matrix of the transparent optical window 15 and the sCMOS detector system response matrix under the scattering direction d can be combined into a system calibration matrix. , is represented as:

[0110] .

[0111] System calibration matrix The calibration can be obtained using standard polarization states, blank simulated tissue fluid, or standard scatterers. Feature extraction module 12 then uses the system calibration matrix... For the original Stokes vector The Stokes vector is corrected by performing the correction. , is represented as:

[0112] .

[0113] When the system calibration matrix When the conditions for direct inversion are not met, a pseudo-inverse matrix can be used for correction. This corrected Stokes vector... Represented as:

[0114] ;

[0115] in, Represents the system calibration matrix The pseudo-inverse matrix.

[0116] By using the above correction method, the fixed polarization effect caused by the transparent optical window 15 and the sCMOS detector response can be deducted or compensated from the measurement results, so that the polarization characteristics obtained later can better reflect the true scattering characteristics of the biological tissue sample 5 under test and the simulated tissue fluid 14 around it.

[0117] The sample positioning structure 10 is disposed within the variable thickness liquid tank 6 and located between the first movable inner wall 4 and the second movable inner wall 7, for fixing the position and orientation of the biological tissue sample 5 to be tested. In this embodiment, the sample positioning structure 10 may be one or more of the following: a sample holder, a transparent sample clamp, a microporous support mesh, a sample positioning stage, a low-stress pressing structure, or a sample thickness limiting structure.

[0118] The liquid level maintaining unit 11 is connected to the control system 13. The liquid level maintaining unit 11 is connected to the liquid chamber through a pipeline. It is used to replenish or discharge the simulated tissue fluid 14 in the liquid chamber according to the control command issued by the control system 13. During the synchronous or differential movement of the first movable inner wall 4 and the second movable inner wall 7, it detects the liquid level change of the simulated tissue fluid 14 in the variable thickness liquid tank 6 and maintains the liquid level of the simulated tissue fluid 14 at a constant level or within a preset liquid level range.

[0119] During actual testing, the space between the first movable inner wall 4, the second movable inner wall 7 and the inner wall of the variable thickness liquid tank 6 is either filled with air or water. When water is injected during the movement of the first movable inner wall 4 and the second movable inner wall 7, the liquid level can be maintained by installing another liquid level holding unit 11.

[0120] In this embodiment, the liquid level maintaining unit 11 includes a liquid level sensor and a liquid level compensation mechanism. The liquid level sensor is disposed on the variable thickness liquid tank 6 and located inside the liquid cavity, and is used to detect the liquid level change of the simulated tissue fluid 14 in the variable thickness liquid tank 6. The liquid level compensation mechanism includes one or more of the following: a replenishment mechanism, a drainage mechanism, an overflow tank, a liquid storage compensation cavity, or a closed compensation cavity, and is used to replenish or drain the simulated tissue fluid 14 in the variable thickness liquid tank 6 according to the detection result of the liquid level sensor, so that the liquid level of the simulated tissue fluid 14 is constant or within a preset liquid level range.

[0121] The feature extraction module 12 is connected to the forward scattering detector 8, the backscattering detector 9, and the control system 13, respectively. It is used to preprocess (background subtraction, dark field correction, flat field correction, image registration, light intensity normalization), reconstruct polarization images, and perform equivalent optical path correction on forward scattering images and backscattering images with multiple polarization directions. Based on the correction results, it calculates the polarization characteristics (Stokes parameters, degree of linear polarization, polarization angle, ratio of forward and backscattering intensity or polarization difference characteristics) of the reconstructed polarization image and plots the thickness response curve of the simulated tissue fluid 14.

[0122] In this embodiment, as Figure 1 , Figure 3 As shown, the control system 13 is connected to the laser 1, the displacement drive mechanism 16, the feature extraction module 12, the forward scattering detector 8, the backscattering detector 9, and the liquid level holding unit 11, respectively. It is used to send control commands, perform data transmission, and associate and store data. The control commands include a start-up control command for the laser 1, a synchronous trigger command for the forward scattering detector 8 and the backscattering detector 9, a control command from the liquid level holding unit 11 to replenish or discharge simulated tissue fluid 14 from the liquid chamber, and a drive command from the displacement drive mechanism 16 to synchronously or differentially move the first movable inner wall 4 and the second movable inner wall 7. Data transmission includes receiving liquid level change information output by the liquid level holding unit 11, the displacement of the first movable inner wall 4 and the second movable inner wall 7 during each acquisition of forward scattering and backscattering images, and the thickness h of the simulated tissue fluid 14; data association and storage includes recording detection state parameters and associating and storing the detection state parameters with polarization characteristics; the detection state parameters include the displacement of the first movable inner wall 4 and the second movable inner wall 7 during each acquisition of forward scattering and backscattering images, the liquid level height of the simulated tissue fluid 14, the thickness of the simulated tissue fluid 14, and the equivalent optical path length of the forward scattering direction within the simulated tissue fluid 14. The equivalent optical path length of the backscattering direction within the simulated tissue fluid 14 Forward scattering direction optical thickness Backscattering direction optical thickness The time for acquiring forward polarization scattering and back polarization scattering signals, the direction of forward polarization scattering and back polarization scattering signals, and the polarization direction of the forward scattering and back scattering images are all determined.

[0123] Through the control system 13, a complete detection dataset containing the thickness, equivalent optical path, polarization characteristics, etc. of the simulated tissue fluid 14 can be obtained, providing a data foundation for subsequent biological tissue identification, lesion analysis, or model training.

[0124] This embodiment also discloses a method for detecting the polarization characteristics of biological tissues based on adjustable tissue fluid thickness, such as... Figure 4As shown, it includes the following steps:

[0125] S1. Fix the biological tissue sample 5 to be tested on the sample positioning structure 10, and add simulated tissue fluid 14 into the liquid cavity to the preset height.

[0126] S2. The control system 13 controls the displacement drive mechanism 16 to drive the first movable inner wall 4 and the second movable inner wall 7 to move synchronously or differentially to the preset thickness h of the simulated tissue fluid 14, and ensures that the equivalent optical path lengths of the forward scattering direction and the backward scattering direction within the simulated tissue fluid 14 satisfy a preset relationship; specifically:

[0127] S21. The displacement drive mechanism 16 is controlled by the control system 13 to drive the first movable inner wall 4 and the second movable inner wall 7 to move differentially to the preset thickness h of the simulated tissue fluid 14.

[0128] S22, Preset equivalent optical path error threshold Calculate the equivalent optical path length of the forward scattering direction within the simulated tissue fluid 14. The equivalent optical path length of the backscattering direction within the simulated tissue fluid 14 Determine whether it satisfies ;

[0129] If so, the equivalent optical path lengths of the forward scattering direction and the backscattering direction within the simulated tissue fluid 14 satisfy the preset relationship, and S23 is executed; otherwise, the first movable inner wall 4 and the second movable inner wall 7 are driven to move synchronously, and S22 is returned.

[0130] S23. The control system 13 controls the liquid level holding unit 11 to maintain the liquid level of the simulated tissue fluid 14 at a constant level or within a preset liquid level range.

[0131] S3. The polarized incident light generator is activated by the control system 13 to emit polarized incident light; at the same time, the forward scattering detector 8 and the backscattering detector 9 are synchronously triggered to acquire forward scattering images and backscattering images of multiple polarization directions within the same triggering period, and output to the feature extraction module 12.

[0132] S4. The feature extraction module 12 preprocesses, reconstructs, and corrects the equivalent optical path of forward scattering and backscattering images in multiple polarization directions. Based on the correction results, it calculates the polarization features of the reconstructed polarization images, including the ratio of forward and backscattering intensities or polarization difference features. Figure 5 As shown, specifically:

[0133] S41. Preprocess the forward scattering images and backscattering images of multiple polarization directions respectively, including background subtraction, dark field correction, flat field correction, image registration, light intensity normalization, equivalent optical path correction and fixed Mueller matrix correction in sequence.

[0134] S42. Reconstruct the forward scattering images with multiple polarization directions after preprocessing to obtain the reconstructed forward scattering image; reconstruct the backscattering images with multiple polarization directions after preprocessing to obtain the reconstructed backscattering image.

[0135] S43. Calculate the correction parameters based on the equivalent optical path difference between the forward scattering direction and the back scattering direction in the simulated tissue fluid 14;

[0136] S44. Perform equivalent optical path correction on the reconstructed forward scattering image and the reconstructed backscattering image respectively, based on the correction parameters.

[0137] S45. Calculate the Stokes parameters, linear polarization degree, and polarization angle of the reconstructed forward scattering image and the reconstructed backscattering image after equivalent optical path correction, and calculate the ratio of forward and backward scattering intensities or polarization difference characteristics.

[0138] Stokes parameters were obtained after equivalent optical path correction under the conditions of scattering direction d and simulated tissue fluid thickness h. Represented as:

[0139] .

[0140] linear polarization degree Represented as:

[0141] .

[0142] polarization angle It can be represented as:

[0143] .

[0144] The correction parameters are calculated based on the equivalent optical path difference between the forward scattering direction and the backscattering direction within the simulated tissue fluid 14. The equivalent optical path of the reconstructed forward scattering image and the reconstructed backscattering image are corrected by combining the correction parameters. This can further solve the problem that the forward scattering direction and the backscattering direction cannot achieve the same geometric propagation distance due to different detection angles. Therefore, even if there is a certain geometric difference between the equivalent optical path of the forward scattering direction and the backscattering direction, it can be corrected by algorithm through geometric calibration and correction parameters to improve the comparability of detection results.

[0145] S5. Change the preset thickness h of the simulated tissue fluid 14, repeat S2-S4, and obtain the polarization features of the reconstructed polarization images corresponding to the thickness of multiple simulated tissue fluid 14. Plot the thickness response curve of the polarization features as the thickness of the simulated tissue fluid 14 changes, and extract the polarization features based on the thickness response curve, including the thickness attenuation coefficient, polarization retention capability index or tissue recognition features.

[0146] The thickness attenuation coefficient is a parameter characterizing how quickly polarization characteristics decay with increasing tissue fluid thickness. It is determined using methods such as exponential fitting, linear fitting, polynomial fitting, or piecewise fitting.

[0147] The polarization retention index characterizes the degree to which polarization information is retained as tissue fluid thickness increases. It can be expressed as the ratio of the degree of linear polarization at a target thickness to the degree of linear polarization at the initial thickness, or as the area under the normalized curve. The larger the index, the stronger the polarization retention capability.

[0148] Tissue identification features are not limited to a single polarization feature on the thickness response curve, but rather are features extracted from the thickness response curve that can distinguish different tissues.

[0149] This embodiment also records the detection state parameters through the control system 13 and stores the detection state parameters in association with the polarization characteristics.

[0150] like Figure 6 The image shows the thicknesses of the feature extraction module 12 in the simulated tissue fluid 14. Under the given conditions, calculate the degree of linear polarization in the forward scattering direction. linear polarization degree in the backscattering direction And plot the thickness response curve of linear polarization degree as a function of simulated tissue fluid thickness h; according to Figure 6 It can be seen that as the thickness h of the simulated tissue fluid 14 increases, the propagation path of the incident light in the simulated tissue fluid 14 becomes longer, and the scattering, absorption and depolarization effects of the simulated tissue fluid 14 on the scattered light are enhanced. Therefore, the linear polarization degree in the forward scattering direction and the backward scattering direction usually shows a decreasing trend.

[0151] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the present invention.

Claims

1. A biological tissue polarization imaging backscattering detection system with adjustable tissue fluid thickness, characterized in that: It includes a polarized incident light generator, a variable thickness liquid tank (6), a first movable inner wall (4), a second movable inner wall (7), a forward scattering detector (8), a backscattering detector (9), a feature extraction module (12), a control system (13), two transparent optical windows (15), a displacement driving mechanism (16), and a sample positioning structure (10). Two transparent optical windows (15) are respectively set on two opposite side walls of the variable thickness liquid tank (6). The first movable inner wall (4) and the second movable inner wall (7) are set in the variable thickness liquid tank (6) between the two transparent optical windows (15). The two and the inner wall of the variable thickness liquid tank (6) form a liquid cavity for holding simulated tissue fluid (14). The working end of the displacement driving mechanism (16) passes through the variable thickness liquid tank (6) and is connected to the first movable inner wall (4) and the second movable inner wall (7) respectively, for driving the first movable inner wall (4) and the second movable inner wall (7) to move synchronously or differentially, so as to change the thickness of the simulated tissue fluid (14) or the equivalent optical path inside. The sample positioning structure (10) is set inside the variable thickness liquid tank (6) and located between the first movable inner wall (4) and the second movable inner wall (7) to fix the biological tissue sample (5) to be tested. The incident light generating device in the polarization state is set relative to one of the transparent optical windows (15) to emit incident light in the polarization state and irradiate the biological tissue sample (5) to be tested through the transparent optical window (15) to form forward polarization scattering signal and backward polarization scattering signal; The forward scattering detector (8) is set in the forward scattering direction where the forward polarization scattering signal is located, and is used to collect the forward polarization scattering signal and generate forward scattering images in multiple polarization directions; The backscattering detector (9) is set in the backscattering direction where the back polarization scattering signal is located, and is used to collect the back polarization scattering signal and generate backscattering images in multiple polarization directions; The control system (13) is connected to the incident light generator in polarization state, the displacement drive mechanism (16), the feature extraction module (12), the forward scattering detector (8), and the backscattering detector (9), respectively, and is used to send control commands, perform data transmission, and associate and store data. The feature extraction module (12) is connected to the forward scattering detector (8) and the backscattering detector (9) respectively. It is used to preprocess, reconstruct polarization images and correct equivalent optical paths of forward scattering images and backscattering images of multiple polarization directions, and calculate the polarization characteristics of the reconstructed polarization images based on the correction results, and draw the thickness response curve of the simulated tissue fluid (14).

2. The biological tissue polarization imaging forward and backward scattering detection system with adjustable tissue fluid thickness according to claim 1, characterized in that: It also includes a liquid level holding unit (11); The liquid level maintaining unit (11) is connected to the control system (13). The liquid level maintaining unit (11) is connected to the liquid cavity area through a pipeline. It is used to detect the liquid level change of the simulated tissue fluid (14) in the variable thickness liquid tank (6) and maintain the liquid level height of the simulated tissue fluid (14) constant or within the preset liquid level range during the synchronous or differential movement of the first movable inner wall (4) and the second movable inner wall (7).

3. The biological tissue polarization imaging forward and backward scattering detection system with adjustable tissue fluid thickness according to claim 2, characterized in that: The liquid level holding unit (11) includes a liquid level sensor and a liquid level compensation mechanism; The liquid level sensor is installed on the variable thickness liquid tank (6) and located inside the liquid cavity, and is used to detect the liquid level change of the simulated tissue fluid (14) in the variable thickness liquid tank (6); The liquid level compensation mechanism includes one or more of the following: a replenishment mechanism, a drainage mechanism, an overflow tank, a liquid storage compensation chamber, or a closed compensation chamber. It is used to replenish or discharge simulated tissue fluid (14) into the variable thickness liquid tank (6) according to the detection results of the liquid level sensor, so that the liquid level of the simulated tissue fluid (14) is constant or within a preset liquid level range.

4. The biological tissue polarization imaging forward and backward scattering detection system with adjustable tissue fluid thickness according to claim 2, characterized in that: The forward scattering detector (8) includes a first micro-polarization array / polarization beam splitter (81) and a first sCMOS detector (82); the first micro-polarization array / polarization beam splitter (81) is disposed in the forward scattering direction where the forward polarization scattering signal is located, and is used to decompose the forward polarization scattering signal into forward light signals with multiple polarization directions; the first sCMOS detector (82) is disposed opposite to the first micro-polarization array / polarization beam splitter (81), and is used to collect forward light signals with multiple polarization directions and generate forward scattering images with multiple polarization directions; The backscattering detector (9) includes a second micro-polarization array / polarization beam splitter (91) and a second sCMOS detector (92); the second micro-polarization array / polarization beam splitter (91) is disposed in the backscattering direction where the backscattering polarization signal is located, and is used to decompose the backscattering polarization signal into backscattering light signals in multiple polarization directions; the second sCMOS detector (92) is disposed opposite to the second micro-polarization array / polarization beam splitter (91), and is used to collect backscattering light signals in multiple polarization directions and generate backscattering images in multiple polarization directions; The first sCMOS detector (82) and the second sCMOS detector (92) are both connected to the control system (13) and the feature extraction module (12). The control system (13) synchronously triggers the first sCMOS detector (82) and the second sCMOS detector (92) to acquire forward scattering images and backscattering images in multiple polarization directions, and sends them to the feature extraction module (12). The first micro-polarization array / polarization beam splitter (81) and the second micro-polarization array / polarization beam splitter (91) are both one or a combination of two of the following: a focal plane micro-polarization array, a multi-channel polarization beam splitter, a polarization beam splitter, or a snapshot Stokes imaging component.

5. The biological tissue polarization imaging forward and backward scattering detection system with adjustable tissue fluid thickness according to claim 1, characterized in that: The transparent optical window (15), the first movable inner wall (4), and the second movable inner wall (7) are all made of quartz glass, optical glass, sapphire glass, or transparent polymer optical materials.

6. The biological tissue polarization imaging forward and backward scattering detection system with adjustable tissue fluid thickness according to claim 1, characterized in that: The incident light generating device in the polarization state includes a laser (1), a collimation system (2), and a polarizer (3) arranged sequentially along the optical axis. The polarizer (3) is positioned opposite to one of the transparent optical windows (15); The laser (1) is connected to the control system (13).

7. The biological tissue polarization imaging forward and backward scattering detection system with adjustable tissue fluid thickness according to claim 2, characterized in that: The control commands include the start control command for the incident light generator in polarization state, the synchronous trigger command for the forward scattering detector (8) and the backscattering detector (9), the control command for the liquid level holding unit (11) to replenish or discharge simulated tissue fluid (14) into the liquid chamber, and the drive command for the displacement drive mechanism (16) to move the first movable inner wall (4) and the second movable inner wall (7) synchronously or differentially. The data transmission includes receiving liquid level change information output by the liquid level holding unit (11), the displacement of the first movable inner wall (4) and the second movable inner wall (7) when acquiring forward scattering and backscattering images each time, and the thickness of the simulated tissue fluid (14). The data association and storage includes recording detection state parameters and associating and storing the detection state parameters with polarization features; the detection state parameters include the displacement of the first movable inner wall (4) and the second movable inner wall (7) each time a forward scattering image and a backscattering image are acquired, the liquid level height of the simulated tissue fluid (14), the thickness of the simulated tissue fluid (14), and the equivalent optical path of the forward scattering direction within the simulated tissue fluid (14). The equivalent optical path length of the backscattering direction in the simulated tissue fluid (14) Forward scattering direction optical thickness Backscattering direction optical thickness The time for acquiring forward polarization scattering and back polarization scattering signals, the direction of forward polarization scattering and back polarization scattering signals, and the polarization direction of the forward scattering and back scattering images; The polarization characteristics include Stokes parameters, degree of linear polarization, polarization angle, ratio of forward and backward scattering intensity, or polarization difference characteristics.

8. A method for detecting forward and backward scattering in biological tissue polarization imaging with adjustable tissue fluid thickness, characterized in that, Using the biological tissue polarization imaging forward and backward scattering detection system with adjustable tissue fluid thickness as described in any one of claims 1-7, the method includes the following steps: S1. Fix the biological tissue sample (5) to be tested on the sample positioning structure (10) and add simulated tissue fluid (14) into the liquid cavity to the preset height; S2. The displacement driving mechanism (16) is controlled by the control system (13) to drive the first movable inner wall (4) and the second movable inner wall (7) to move synchronously or differentially to the preset thickness h of the simulated tissue fluid (14), and to make the equivalent optical path of the forward scattering direction and the backward scattering direction in the simulated tissue fluid (14) satisfy the preset relationship. S3. The polarized incident light generator is activated by the control system (13) to emit polarized incident light; at the same time, the forward scattering detector (8) and the backscattering detector (9) are synchronously triggered to collect forward scattering images and backscattering images of multiple polarization directions within the same triggering period, and output to the feature extraction module (12). S4. The feature extraction module (12) preprocesses, reconstructs, and corrects the equivalent optical path of forward scattering images and backscattering images in multiple polarization directions, and calculates the polarization features of the reconstructed polarization images based on the correction results. S5. Change the preset thickness h of the simulated tissue fluid (14), repeat S2-S4, and obtain the polarization features of the reconstructed polarization images corresponding to the thickness of multiple simulated tissue fluids (14). Plot the thickness response curve of the polarization features changing with the thickness of the simulated tissue fluid (14), and extract the thickness attenuation coefficient, polarization retention capability index or tissue recognition features based on the thickness response curve.

9. The biological tissue polarization imaging backscattering detection method with adjustable tissue fluid thickness according to claim 8, characterized in that, S2 specifically refers to: S21. The displacement drive mechanism (16) is controlled by the control system (13) to drive the first movable inner wall (4) and the second movable inner wall (7) to move differentially to the preset thickness h of the simulated tissue fluid (14); S22, Preset equivalent optical path error threshold Calculate the equivalent optical path length of the forward scattering direction in the simulated tissue fluid (14). The equivalent optical path length of the backscattering direction in the simulated tissue fluid (14) Determine whether it satisfies ; If so, the equivalent optical path lengths of the forward scattering direction and the backward scattering direction in the simulated tissue fluid (14) satisfy the preset relationship, and S23 is executed; otherwise, the first movable inner wall (4) and the second movable inner wall (7) are driven to move synchronously, and S22 is returned. S23. The control system (13) controls the liquid level holding unit (11) to maintain the liquid level of the simulated tissue fluid (14) at a constant level or within a preset liquid level range.

10. The method for detecting forward and backward scattering in biological tissue polarization imaging with adjustable tissue fluid thickness according to claim 8, characterized in that, S4 specifically refers to: S41. Preprocess the forward scattering images and backscattering images of multiple polarization directions respectively, including background subtraction, dark field correction, flat field correction, image registration, light intensity normalization, equivalent optical path correction and fixed Mueller matrix correction in sequence. S42. Reconstruct the forward scattering images with multiple polarization directions after preprocessing to obtain the reconstructed forward scattering image; reconstruct the backscattering images with multiple polarization directions after preprocessing to obtain the reconstructed backscattering image. S43. Calculate the correction parameters based on the equivalent optical path difference between the forward scattering direction and the back scattering direction in the simulated tissue fluid (14); S44. Perform equivalent optical path correction on the reconstructed forward scattering image and the reconstructed backscattering image respectively, based on the correction parameters. S45. Calculate the Stokes parameters, linear polarization degree, and polarization angle of the reconstructed forward scattering image and the reconstructed backscattering image after equivalent optical path correction, and calculate the ratio of forward and backward scattering intensities or polarization difference characteristics.

Images