A method for polarization state imaging depth reconstruction based on polarization state coherent synthesis

Abstract

The present invention relates to a method for deep reconstruction of polarization state imaging based on polarization state coherent synthesis, which comprises the following steps: S1: coherently synthesizing a reflected reference light and a reflected sample light whose polarization directions are perpendicular to each other to obtain a synthesized light, and measuring the polarization information of the synthesized light to obtain a polarization light intensity map at the current depth; S2: deriving Stokes parameters according to the polarization light intensity map at the current depth, thereby determining the polarization state of the synthesized light; S3: solving the polarization information at the current depth according to the polarization state of the synthesized light. The method for deep reconstruction of polarization state imaging based on polarization state coherent synthesis of the present invention has the advantages of simple mathematical operations and richer reconstruction information.

Description

Technical Field

[0001] The present invention relates to the technical field of polarization tomography, and in particular to a polarization state imaging depth reconstruction method based on polarization state coherent synthesis. Background Art

[0002] When polarized light interacts with matter, its polarization state changes, which can reflect the polarization properties of the matter. Therefore, it has been widely used to explore biological tissues such as the retina, muscle fibers, and connective tissue. When the structure or function of biological tissue changes, its polarization properties will also change. Polarization imaging methods can obtain partial or full polarization information of the sample, which is helpful for studying the changes in polarization properties caused by pathological changes in tissue structure, and thus provides a reference for medical diagnosis of diseased tissues. However, traditional polarization imaging techniques such as polarization intensity imaging and Mueller matrix imaging cannot independently extract partial or full polarization information at a certain depth of the sample, and thus cannot achieve tomography effects.

[0003] In addition, the development of optical coherence tomography (OCT) provides new technical support for studying information at different depths of the same sample. It uses the reflection and scattering signals of biological tissue to obtain optical images, and can achieve high-resolution optical tomography of biological tissue samples, mainly reflecting the scattering characteristics of the sample.

[0004] Polarization-sensitive optical coherence tomography (PS-OCT) is a new imaging technology that combines polarization imaging technology with optical coherence tomography technology. It adds polarization devices to OCT to achieve polarization tomography. Figure 1 , which is a flow chart of the steps of a polarization tomography demodulation method based on polarization light interference in the prior art. The polarization tomography demodulation method includes the following steps: obtaining a polarization intensity map of interference light through polarization light interference; wherein the polarization intensity map includes 4 horizontal interference intensity maps and 4 vertical interference intensity maps; obtaining the amplitude and phase of horizontal polarized light and the amplitude and phase of vertical polarized light according to the polarization intensity map demodulation; and solving the phase difference according to the phase of horizontal polarized light and the phase of vertical polarized light.

[0005] However, the polarization tomography demodulation method has the following defects: when imaging the same depth of the sample, this method needs to collect multiple interference light intensity images in different time periods to form a set of equations, and then demodulate the set of equations. This time-sharing and step-by-step imaging method has the limitations of slow imaging speed, large amount of mathematical calculations, and high algorithm complexity. On the other hand, this method reconstructs the depth information of the sample by calculating the amplitude and phase of the interference light. The information obtained is insufficiently rich and cannot present the polarization state tomography of the sample at the same depth. Summary of the invention

[0006] Based on this, the purpose of the present invention is to provide a polarization state imaging depth reconstruction method based on polarization state coherent synthesis, which has the advantages of simple mathematical operations, richer reconstruction information and higher visualization.

[0007] The present invention is achieved through the following technical solutions:

[0008] A method for polarization state imaging depth reconstruction based on polarization state coherent synthesis comprises the following steps:

[0009] S1: performing coherent synthesis of the reflected reference light and the reflected sample light whose polarization directions are perpendicular to each other to obtain synthesized light, and measuring the polarization information of the synthesized light to obtain a polarization light intensity map of the current depth of the sample;

[0010] S2: deriving Stokes parameters according to the polarization intensity map of the current depth, thereby determining the polarization state of the synthetic light;

[0011] S3: According to the polarization state of the synthetic light, the polarization information of the current depth is solved.

[0012] The polarization state imaging depth reconstruction method based on polarization state coherent synthesis described in the present invention can directly solve the polarization light intensity map without solving multiple equations, the mathematical operation is simple, and the information obtained is richer.

[0013] Furthermore, the method further comprises the steps of:

[0014] S4: Draw a polarization state tomography chromaticity value diagram of the current depth according to the polarization information of the current depth.

[0015] The polarization state tomography chromaticity value diagram can intuitively display the depth information and polarization information of the sample with a high degree of visualization.

[0016] Furthermore, step S1 includes sub-steps:

[0017] S11: Splitting the incident linear polarized light to obtain an incident reference light and an incident sample light, and making the polarization directions of the incident reference light and the incident sample light perpendicular to each other;

[0018] S12: directly reflecting the incident reference light to obtain the reflected reference light, and reflecting the incident sample light on the sample to obtain the reflected sample light, and then coherently modulating the reflected reference light and the reflected sample light respectively to ensure that the polarization directions of the reflected reference light and the reflected sample light are perpendicular to each other;

[0019] S13: performing coherent synthesis on the reflected reference light and the reflected sample light whose polarization directions are perpendicular to each other to obtain the synthesized light;

[0020] S14: measuring polarization information of the synthetic light to obtain a polarized light intensity image.

[0021] Furthermore, the polarization state of the synthetic light is expressed as:

[0022]

[0023] In the formula, S superposition represents the polarization state of the synthetic light, including the polarization information of all depths of the sample; S0(z) represents the total light intensity parameter of all depths, S1(z) represents the first linear polarization parameter of all depths, S2(z n ) represents the second linear polarization parameter of the current depth, S3(z n ) represents the circular polarization parameter of the current depth; E r represents the amplitude of the reflected reference light, E s represents the amplitude of the reflected sample light; z represents all depths in the sample, z n represents the current depth (or the nth depth) of the sample, where n is a positive integer; δ represents the phase difference between the reflected reference light and the reflected sample light at the current depth.

[0024] Furthermore, step S3 is specifically as follows:

[0025] The second linear polarization parameter of the current depth and the circular polarization parameter of the current depth are derived from the polarization state of the synthetic light, and the amplitude signal of the reflected sample light at the current depth is solved; based on the amplitude signal of the reflected sample light at the current depth, the total light intensity parameter of the current depth and the first linear polarization parameter of the current depth are solved, and the polarization information of the current depth is determined.

[0026] Furthermore, the calculation formula of the amplitude signal of the reflected sample light at the current depth is:

[0027]

[0028] The calculation formula of the total light intensity parameter at the current depth is:

[0029]

[0030] The calculation formula of the first linear polarization parameter of the current depth is:

[0031]

[0032] The calculation formula of the polarization information of the current depth is:

[0033]

[0034] In the formula, S layer (z n ) represents the polarization information of the current depth, S0(z n ) represents the total light intensity parameter of the current depth, S1(z n ) represents the first linear polarization parameter of the current depth.

[0035] Furthermore, step S4 is specifically as follows:

[0036] The accurate synthetic polarization state at the current depth is normalized to obtain normalized accurate Stokes parameters; color coding is performed according to the normalized accurate Stokes parameters to obtain values ​​of three primary colors; and a polarization state tomography chromaticity value diagram at the current depth is drawn according to the values ​​of the three primary colors.

[0037] Furthermore, after obtaining the polarization information of the current depth, a calibration method of a polarization state component transmission matrix is ​​used to solve the accurate polarization information of the current depth, and then an accurate polarization state tomography chromaticity value diagram is drawn according to the accurate polarization information of the current depth.

[0038] Furthermore, the calculation formula for the accurate polarization information of the current depth is:

[0039]

[0040] in, and The calculation formula is:

[0041]

[0042] and The calculation formula is:

[0043]

[0044] In the formula, Indicates accurate polarization information of current depth; Indicates the accurate total light intensity parameter at the current depth, Indicates the accurate first linear polarization parameter of the current depth, Indicates the accurate second linear polarization parameter of the current depth, Indicates the accurate circular polarization parameter of the current depth; S2(z n ) represents the second linear polarization parameter of the current depth, S3(z n ) represents the circular polarization parameter of the current depth, E r represents the amplitude of the reflected reference light; T represents a 2×2 transmission matrix, which describes the instrument error during polarization state measurement.

[0045] Furthermore, the expression of the transmission matrix is:

[0046] T=[T1 T2] (26)

[0047] Wherein, T1 and T2 represent the first column coefficient and the second column coefficient of the transmission matrix respectively;

[0048] The calculation formula of the first column coefficient is:

[0049]

[0050] The calculation formula of the second column coefficient is:

[0051]

[0052] In the formula, s in () represents the partial polarization information of the standard incident polarization state, s out () represents partial polarization information of the standard output polarization state; is the azimuth angle of the standard incident polarization state, k∈[0,35].

[0053] Compared with the prior art, the polarization state tomography depth reconstruction method based on polarization state coherent synthesis provided by the present invention can not only directly solve the polarization light intensity image without solving multiple equations, and the mathematical operation is simple, but also can reconstruct the polarization state tomography chromaticity value diagram of the sample at different depths, and simultaneously display the depth information and polarization information of the sample, with richer information and high visualization; in addition, the calibration method of the polarization state component transmission matrix is ​​adopted to solve and obtain the accurate polarization information of the sample, and a more accurate polarization state tomography chromaticity value diagram is drawn, which can further improve the accuracy of polarization tomography.

[0054] For better understanding and implementation, the present invention is described in detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Figure 1 It is a flow chart of the steps of a polarization tomography demodulation method based on polarized light interference in the prior art;

[0056] Figure 2A flowchart of the steps of a polarization state imaging depth reconstruction method based on polarization state coherent synthesis proposed in one embodiment of the present invention;

[0057] Figure 3 A schematic diagram of a process for reconstructing a polarization state tomography chromaticity value map from a polarization light intensity map provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0058] In order to avoid the limitations of the polarization tomography demodulation method based on polarization interference in the prior art, such as large amount of mathematical calculation, high algorithm complexity, insufficient information richness, etc., the present invention obtains the polarization light intensity map of the sample at different depths through polarization state coherent imaging, and then uses the orthogonal polarization state demodulation method to directly solve the polarization light intensity map, which has simple mathematical calculations, richer information, and higher visualization. The technical solution of the present invention is further explained in conjunction with specific embodiments.

[0059] Example 1

[0060] See also Figure 2 , which is a flowchart of the steps of a polarization state imaging depth reconstruction method based on polarization state coherent synthesis proposed in this embodiment. The polarization state imaging depth reconstruction method includes the steps of:

[0061] S1: Coherently combine the reflected reference light and the reflected sample light with polarization directions perpendicular to each other to obtain the synthesized light, measure the polarization information of the synthesized light, and obtain the polarization light intensity map of the current depth of the sample;

[0062] S2: derive Stokes parameters based on the polarization intensity map of the current depth and determine the polarization state of the synthetic light;

[0063] S3: according to the polarization state of the synthetic light, solve the polarization information of the current depth;

[0064] S4: Draw a polarization state tomography chromaticity value diagram of the current depth according to the polarization information of the current depth.

[0065] Specifically, step 1 includes sub-steps:

[0066] S11: Splitting the incident linear polarized light to obtain an incident reference light and an incident sample light, and making the polarization directions of the incident reference light and the incident sample light perpendicular to each other;

[0067] S12: directly reflecting the incident reference light to obtain reflected reference light, and simultaneously reflecting the incident sample light on the sample to obtain reflected sample light, and then coherently modulating the reflected reference light and the reflected sample light respectively to ensure that the polarization directions of the reflected reference light and the reflected sample light are perpendicular to each other;

[0068] S13: performing coherent synthesis on the reflected reference light and the reflected sample light whose polarization directions are perpendicular to each other to obtain synthesized light;

[0069] S14: measuring polarization information of the synthesized light to obtain a polarized light intensity image.

[0070] Within the imaging depth (or within the coherence length of the incident linear polarized light), the synthetic light at the current depth of the sample is obtained by polarization state coherent synthesis, and a set of polarization light intensity maps is measured, each of which includes 6 light intensity images.

[0071] Assuming that n depths of the sample are detected within the imaging depth, and n groups of polarization intensity maps are obtained, the expressions of the polarization intensity maps of the current depth (or the nth group) are:

[0072]

[0073] In the formula, I 0° is the light intensity data of the linear polarization component with an azimuth angle of 0°; I 45° is the light intensity data of the linear polarization component with an azimuth angle of 45°; 90° I represents the light intensity data of the linear polarization component with an azimuth angle of 90°; 135° Represents the light intensity data of the linear polarization component with an azimuth angle of 135°; L I is the light intensity data representing the left circular polarization component; R Represents the light intensity data of the right circular polarization component; E r represents the amplitude of the reflected reference light, E s represents the amplitude of the light reflected from the sample; z represents all depths in the sample, z n represents the current depth (or nth depth) of the sample, where n is a positive integer; δ represents the phase difference between the reflected reference light and the reflected sample light at the current depth.

[0074] For any given depth, E r is constant, so I 0° is also constant; I 90° It is the superposition of the reflected sample light from all depths of the sample, including information about the current depth and other depths. 45° ,I 135° ,I R and I L , E s (z n ) is a coherent term, since the coherent combination of polarization states occurs only at the current depth of the sample.

[0075] In step S2, this embodiment uses the Stokes vector to represent the polarization state of the synthesized light, where the Stokes vector is defined as:

[0076]

[0077] In the formula, S represents the Stokes vector, S0 represents the total light intensity parameter, S1 represents the first linear polarization parameter, S2 represents the second linear polarization parameter, and S3 represents the circular polarization parameter. In addition, the Stokes vector can be expressed in the form of amplitude and phase difference, E x represents the amplitude in the horizontal polarization direction, E y represents the amplitude in the vertical polarization direction, and θ represents the phase difference between horizontally polarized light and vertically polarized light.

[0078] It can be seen from formula (7) that the Stokes vector of a beam of polarized light contains 6 different light intensity data, which correspond to the 6 light intensity images in the polarization light intensity map of the current depth obtained in step S1. Therefore, four Stokes parameters can be derived according to the polarization light intensity map of the current depth, thereby determining the polarization state of the synthetic light.

[0079] Then, the expression of the polarization state of the synthetic light is:

[0080]

[0081] In the formula, S superposition represents the polarization state of the synthetic light, including the polarization information of all depths of the sample; S0(z) represents the total light intensity parameter of all depths, S1(z) represents the first linear polarization parameter of all depths, and both of them contain the polarization information of all depths of the sample; S2(z n ) represents the second linear polarization parameter of the current depth, S3(z n ) represents the circular polarization parameter of the current depth. Both of them only contain the current depth (i.e., the nth depth z n )’s polarization information.

[0082] It can be seen from formula (8) that the polarization state of the synthesized light cannot directly obtain the total light intensity parameter of the current depth and the first linear polarization parameter of the current depth. Therefore, it is necessary to extract the polarization information of the current depth from the polarization state of the synthesized light.

[0083] In step S3, this embodiment uses an orthogonal polarization state demodulation method to extract the polarization information of the current depth from the polarization state of the synthetic light, wherein the orthogonal polarization state demodulation method is a method for extracting the polarization information of the current depth based on the orthogonality of the second linear polarization parameter and the circular polarization parameter. It can be seen from formula (8) that S2(z n ) and S3(z n ) is the difference in the trigonometric function terms; according to the knowledge of Fourier series, these two trigonometric function terms are orthogonal, that is, S2(z n ) and S3(z n ) are orthogonal. Therefore, according to S2(zn ) and S3(z n ) is used to solve the total light intensity parameter at the current depth and the first linear polarization parameter at the current depth, thereby obtaining the polarization information at the current depth. The solution process is:

[0084] The second linear polarization parameter at the current depth and the circular polarization parameter at the current depth are derived from the polarization state of the synthetic light, and the amplitude signal of the reflected sample light at the current depth is solved. The calculation formula is:

[0085]

[0086] According to the amplitude signal of the reflected sample light at the current depth, the total light intensity parameter at the current depth and the first linear polarization parameter at the current depth are solved to determine the polarization information at the current depth:

[0087] The calculation formula of the total light intensity parameter at the current depth is:

[0088]

[0089] The calculation formula of the first linear polarization parameter at the current depth is:

[0090]

[0091] The calculation formula for the polarization information of the current depth is:

[0092]

[0093] In the formula, S layer (z n ) represents the polarization information of the current depth, and only contains the polarization information of the current depth of the sample; S0(z n ) represents the total light intensity parameter at the current depth, S1(z n ) represents the first linear polarization parameter of the current depth, and the two are obtained by orthogonal polarization state demodulation method; S2(z n ) represents the second linear polarization parameter of the current depth, S3(z n ) represents the circular polarization parameter of the current depth, and both are directly obtained by formula (8).

[0094] In step S4, the synthetic polarization state at the current depth is normalized to obtain normalized Stokes parameters; color coding is performed according to the normalized Stokes parameters to obtain values ​​of three primary colors; and a polarization state tomography chromaticity value diagram at the current depth is drawn according to the values ​​of the three primary colors.

[0095] Among them, the calculation formulas of the normalized Stokes parameters are:

[0096]

[0097]

[0098] In the formula, S'0(z n ) represents the normalized total light intensity parameter, S'1 represents the normalized first linear polarization parameter, S'2(z n ) represents the normalized second linear polarization parameter, S'3(z n ) represents the normalized circular polarization parameter; the normalized total light intensity parameter is 1, and the values ​​of the other three normalized Stokes parameters are [-1,1].

[0099] The calculation formula for the red primary color is:

[0100]

[0101] The calculation formula for green primary color is:

[0102]

[0103] The calculation formula for the blue primary color is:

[0104]

[0105] Among them, the red primary color corresponds to the normalized first linear polarization parameter, the green primary color corresponds to the normalized second linear polarization parameter, and the blue primary color corresponds to the normalized circular linear polarization parameter. The values ​​of the three primary colors are all [0,1].

[0106] See also Figure 3 , which is a schematic diagram of the process of reconstructing the polarization state tomography chromaticity value map from the polarization light intensity map provided by this embodiment. First, four silver wires are stacked and buried in agar gel to prepare a sample, and the sample is subjected to polarization state tomography imaging to detect 4 different sample depths (i.e., n=4). The 4 sample depths are respectively recorded as z1, z2, z3, and z4, thereby obtaining 4 sets of polarization light intensity maps. Then, through steps S2 to S4, the polarization state tomography chromaticity value maps of 4 different depths are reconstructed, thereby intuitively obtaining the depth information and polarization information of the sample.

[0107] Compared with the prior art, the polarization state tomography depth reconstruction method based on polarization state coherent synthesis provided in this embodiment can not only directly solve the polarization light intensity image without solving multiple equations and simple mathematical operations, but also can reconstruct the polarization state tomography chromaticity value diagram of the sample at different depths, and simultaneously display the depth information and polarization information of the sample, with richer information and high visualization; in addition, when obtaining the polarization light intensity diagram, the method also has the advantages of fast imaging speed and high measurement accuracy.

[0108] Example 2

[0109] The polarization state tomography depth reconstruction method described in Example 1 is a method step under an ideal state, and does not take into account the instrument error that may exist when measuring the polarization information of the synthetic light to collect the polarization light intensity image. The polarization light intensity image obtained by measurement cannot accurately reflect the polarization information of the sample. Therefore, this embodiment calibrates the polarization information of the current depth obtained in Example 1 to obtain accurate polarization information of the sample.

[0110] That is to say, after obtaining the polarization information of the current depth, the calibration method of the polarization state component transmission matrix is ​​used to solve the accurate polarization information of the current depth, and then the accurate polarization state tomography chromaticity value diagram is drawn according to the accurate polarization information of the current depth.

[0111] Specifically, the calculation formula for the accurate polarization information of the current depth is:

[0112]

[0113] in, and The calculation formula is:

[0114]

[0115] and The calculation formula is:

[0116]

[0117] In the formula, Indicates accurate polarization information of current depth; Indicates the accurate total light intensity parameter at the current depth, Indicates the accurate first linear polarization parameter of the current depth, Indicates the accurate second linear polarization parameter of the current depth, Represents the accurate circular polarization parameters at the current depth; T represents a 2×2 transmission matrix, which describes the instrument error during polarization state measurement.

[0118] If there is no measurement error when measuring the polarization state (i.e., the ideal state of Example 1), the transmission matrix is ​​a unit matrix; if there is a measurement error when measuring the polarization state, the transmission matrix is ​​a non-unit matrix, and the transmission matrix that describes the instrument error must be determined to obtain accurate polarization information at the current depth.

[0119] The transfer matrix can be determined using the following method:

[0120] A linear polarizer and a quarter-wave plate (QWP) are sequentially arranged on the optical axis of the synthetic light in front of the polarization state measurement device; wherein the fast axis azimuth angle of the linear polarizer is 45°, and the fast axis azimuth angle of the quarter-wave plate is k∈[0,35];

[0121] By gradually increasing k from 0 to 35 and changing the fast axis azimuth of the quarter wave plate, that is, rotating the quarter wave plate at intervals of 5°, the fast axis azimuth is changed from 0° to 175°, and 36 sets of linearly independent standard incident polarization states and standard output polarization states are obtained respectively;

[0122] According to the standard incident polarization state and the standard output polarization state, the transmission matrix is ​​solved.

[0123] According to the Stokes-Mueller transmission theory, the polarization state of a light is represented by the Stokes vector. When it passes through an optical device, it is equivalent to the Mueller matrix of the optical device multiplied by the polarization state of the light. Then, the expression of the standard incident polarization state is:

[0124]

[0125] In the formula, S in represents the standard incident polarization state; M QWP (α) represents the Mueller matrix of the quarter wave plate, which describes the effect of the quarter wave plate on the standard incident polarization state; is the fast axis azimuth of the 1 / 4 wave plate, which is also the azimuth of the standard incident polarization state; S 45° Represents linearly polarized light with an azimuth angle of 45°.

[0126] The last two components of the standard incident polarization state are taken to obtain the partial polarization information of the standard incident polarization state, and its expression is:

[0127]

[0128] In the formula, s in (α) represents the partial polarization information of the standard incident polarization state.

[0129] Then, the expression of partial polarization information of the standard output polarization state is:

[0130]

[0131] In the formula, s out (α) represents the partial polarization information of the standard output polarization state, and T1 and T2 represent the first column coefficient and the second column coefficient of the transmission matrix respectively.

[0132] The expansion of the relationship between the standard incident polarization state and the standard output polarization state with respect to the transmission matrix satisfies the Fourier series expansion form. Therefore, the two coefficients in formula (16) can be solved by the method of solving the Fourier series, and then:

[0133] The calculation formula for the first column coefficient is:

[0134]

[0135] The calculation formula for the second column coefficient is:

[0136]

[0137] The transmission matrix can be determined based on the coefficients of the first column and the second column, and its expression is:

[0138] T=[T1 T2] (26)

[0139] From the above, it can be seen that the transmission matrix of the polarization state transmission device is determined according to formula (26), and the polarization information of the current depth (corresponding to the standard incident polarization state) is obtained according to steps S1 to S3 of Example 1. Then, the accurate polarization information of the current depth (corresponding to the standard exit polarization state) can be solved according to formula (20).

[0140] It should be noted that when the above calibration method is used to determine the transmission matrix of the polarization state transmission device, a linear polarizer and a quarter wave plate are introduced. After the calibration is completed, the linear polarizer and the quarter wave plate should be removed, that is, in the process of obtaining the polarization intensity map of the synthetic light through polarization state tomography, it is not necessary to set up an additional linear polarizer and a quarter wave plate in front of the polarization state transmission device.

[0141] Compared with the prior art, the polarization state tomography deep reconstruction method based on polarization state coherent synthesis provided in this embodiment adopts the calibration method of the polarization state component transmission matrix to solve and obtain the accurate polarization information of the sample, and draws a more accurate polarization state tomography chromaticity value diagram, which can further improve the accuracy of polarization tomography.

[0142] 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 invention patent. 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 method for deep reconstruction of polarization state imaging based on polarization state coherent synthesis, characterized in that: Includes steps: S1: performing coherent synthesis of the reflected reference light and the reflected sample light whose polarization directions are perpendicular to each other to obtain synthesized light, and measuring the polarization information of the synthesized light to obtain a polarization light intensity map of the current depth of the sample; S2: deriving Stokes parameters according to the polarization intensity map of the current depth, thereby determining the polarization state of the synthetic light; S3: solving the polarization information of the current depth according to the polarization state of the synthetic light; S4: drawing a polarization state tomography chromaticity value diagram of the current depth according to the polarization information of the current depth; In step S2, the Stokes vector is used to represent the polarization state of the synthesized light, wherein the Stokes vector is defined as: Where S represents the Stokes vector, S0 represents the total light intensity parameter, S1 represents the first linear polarization parameter, S2 represents the second linear polarization parameter, and S3 represents the circular polarization parameter. In addition, the Stokes vector is expressed in the form of amplitude and phase difference, E x represents the amplitude in the horizontal polarization direction, E y represents the amplitude in the vertical polarization direction, and θ represents the phase difference between horizontally polarized light and vertically polarized light; The expression of the polarization state of the synthetic light is: In the formula, S superposition represents the polarization state of the synthetic light, including the polarization information of all depths of the sample; S0(z) represents the total light intensity parameter of all depths, S1(z) represents the first linear polarization parameter of all depths, S2(z n ) represents the second linear polarization parameter of the current depth, S3(z n ) represents the circular polarization parameter of the current depth; E r represents the amplitude of the reflected reference light, E s represents the amplitude of the reflected sample light; z represents all depths in the sample, z n represents the current depth (or nth depth) of the sample, where n is a positive integer; δ represents the phase difference between the reflected reference light and the reflected sample light at the current depth; Step S3 is specifically as follows: Deriving the second linear polarization parameter of the current depth and the circular polarization parameter of the current depth from the polarization state of the synthetic light, and solving the amplitude signal of the reflected sample light at the current depth; solving the total light intensity parameter of the current depth and the first linear polarization parameter of the current depth according to the amplitude signal of the reflected sample light at the current depth, and determining the polarization information of the current depth; The calculation formula of the amplitude signal of the reflected sample light at the current depth is: The calculation formula of the total light intensity parameter at the current depth is: The calculation formula of the first linear polarization parameter of the current depth is: The calculation formula of the polarization information of the current depth is: In the formula, S layer (z n ) represents the polarization information of the current depth, S0(z n ) represents the total light intensity parameter of the current depth, S1(z n ) represents a first linear polarization parameter of the current depth; Step S4 specifically includes: normalizing the accurate synthetic polarization state of the current depth to obtain normalized accurate Stokes parameters; performing color coding according to the normalized accurate Stokes parameters to obtain values ​​of three primary colors; and drawing a polarization state tomography chromaticity value diagram of the current depth according to the values ​​of the three primary colors.

2. The method for polarization state imaging depth reconstruction based on polarization state coherent synthesis according to claim 1, characterized in that: Step S1 includes sub-steps: S11: Splitting the incident linear polarized light to obtain an incident reference light and an incident sample light, and making the polarization directions of the incident reference light and the incident sample light perpendicular to each other; S12: directly reflecting the incident reference light to obtain the reflected reference light, and reflecting the incident sample light on the sample to obtain the reflected sample light, and then coherently modulating the reflected reference light and the reflected sample light respectively to ensure that the polarization directions of the reflected reference light and the reflected sample light are perpendicular to each other; S13: performing coherent synthesis on the reflected reference light and the reflected sample light whose polarization directions are perpendicular to each other to obtain the synthesized light; S14: measuring polarization information of the synthetic light to obtain a polarized light intensity image.

3. The method for polarization state imaging depth reconstruction based on polarization state coherent synthesis according to claim 1, characterized in that: After obtaining the polarization information of the current depth, the calibration method of the polarization state component transmission matrix is ​​used to solve the accurate polarization information of the current depth, and then an accurate polarization state tomography chromaticity value diagram is drawn according to the accurate polarization information of the current depth.

4. The method for polarization state imaging depth reconstruction based on polarization state coherent synthesis according to claim 3, characterized in that: The calculation formula for the accurate polarization information of the current depth is: in, and The calculation formula is: and The calculation formula is: In the formula, Indicates accurate polarization information of current depth; Indicates the accurate total light intensity parameter at the current depth, Indicates the accurate first linear polarization parameter of the current depth, Indicates the accurate second linear polarization parameter of the current depth, Indicates the accurate circular polarization parameter of the current depth; S2(z n ) represents the second linear polarization parameter of the current depth, S3(z n ) represents the circular polarization parameter of the current depth, E r represents the amplitude of the reflected reference light; T represents a 2×2 transmission matrix, which describes the instrument error during polarization state measurement.

5. The method for polarization state imaging depth reconstruction based on polarization state coherent synthesis according to claim 4, characterized in that: The expression of the transmission matrix is: T=[T1 T2] (26) Wherein, T1 and T2 represent the first column coefficient and the second column coefficient of the transmission matrix respectively; The calculation formula of the first column coefficient is: The calculation formula of the second column coefficient is: In the formula, s out () represents partial polarization information of the standard output polarization state; is the azimuth angle of the standard incident polarization state, k∈[0,35].

Images