A multi-wavelength compatible single-exposure full stokes polarimetry device and method

Abstract

This invention provides a multi-wavelength compatible single-exposure full Stokes polarization imaging device and method. The device includes a light source, filters, an object under test, lenses, apertures, a two-dimensional orthogonal Rownchi grating, a 4F system, a custom decoupled polarization modulation mask, and a grayscale camera. The grating is placed on the object plane of the 4F system to replicate the offset spectrum, and the mask is placed near the Fourier plane, integrating an achromatic polarizer and a delay plate. A time-delay strategy is used to decouple the four polarization channels. The camera acquires an coded image in a single exposure, and the polarization components are separated by Fourier transform decoding to reconstruct the full Stokes image. This invention eliminates the need for traditional system-level calibration, requiring only a single pre-calibration of the mask's single-point Stokes response, significantly simplifying the process and providing an efficient imaging solution for multi-wavelength scenarios.

Description

Technical Field

[0001] This invention belongs to the field of polarization imaging and computational optical imaging technology, specifically relating to a multi-wavelength compatible single-exposure full Stokes polarization imaging device and method. Background Technology

[0002] Full Stokes polarization imaging technology can acquire complete polarization information (S0, S1, S2, S3) of a target, effectively revealing target physical properties that are imperceptible to traditional intensity imaging. It has significant application value in many fields such as materials characterization, biological tissue imaging, and target detection. Among these applications, extending the system's operating spectral bandwidth to achieve multi-wavelength compatible polarization imaging is a crucial research direction. However, existing full Stokes imaging methods face the following challenges: 1) Most methods are limited by the operating wavelength or require time-consuming and complex system-level calibration at different spectra; 2) Insufficient temporal resolution makes it difficult to capture dynamic scenes; 3) Measurements of the circular polarization component (S3), in particular, are wavelength-sensitive, and the calibration process is cumbersome. Therefore, developing a multi-wavelength compatible technique that is easy to calibrate and can acquire full Stokes polarization images in a single exposure has significant research and application value. Summary of the Invention

[0003] Purpose of the invention: To overcome the shortcomings of existing all-Stokes polarization imaging technology, such as poor wavelength adaptability, complex system-level calibration, and large channel crosstalk, this invention proposes a multi-wavelength compatible single-exposure all-Stokes polarization imaging device and method. By using a parallel decoupled spatial frequency modulation structure and a customized polarization mask design, multi-wavelength compatible single-exposure all-Stokes imaging is achieved, greatly simplifying the calibration process, eliminating inter-channel crosstalk, and providing an efficient and reliable technical solution for broadband polarization imaging.

[0004] The device includes a broadband collimated LED light source, a filter, an object under test, a first lens, an aperture, a second lens, a two-dimensional orthogonal Ronchi grating, a 4F optical system, a custom decoupled polarization modulation mask, and a grayscale camera imaging detector.

[0005] The object to be tested is positioned on the front focal plane of the first lens;

[0006] The aperture stop is positioned at the rear focal plane of the first lens;

[0007] The distance between the second lens and the aperture stop is one focal length of the second lens;

[0008] The two-dimensional orthogonal Ronchi grating is disposed on the back focal plane of the second lens;

[0009] The 4F optical system includes a third lens and a fourth lens;

[0010] The two-dimensional orthogonal Ronchi grating is set on the object plane of the 4F optical system to modulate the spatial distribution of the incident target light, realize the replication and shift of the spectrum, generate multiple sets of replicated spectral components in the Fourier plane, and retain only 4 sets of ±1 order diffraction spectral components for subsequent processing. The first set is (0, +1) and (0, -1); the second set is (+1, 0) and (-1, 0); the third set is (+1, +1) and (-1, -1); and the fourth set is (-1, +1) and (+1, -1).

[0011] The customized decoupled polarization modulation mask is set in or near the Fourier plane of the 4F optical system to perform polarization analysis on the four retained ±1st order diffraction spectrum components, corresponding to four polarization channels: 0°, 90°, 135°, and left-handed circular polarization. The decoupling of the four polarization channels is achieved through a time-optical delay strategy to eliminate crosstalk between channels.

[0012] The imaging detector is used to acquire the coded intensity image output by the 4F optical system in a single exposure, and the four polarization components are separated by digital fast Fourier transform decoding. The full Stokes vector image is reconstructed based on the pre-calibrated single-point response.

[0013] The units work together to achieve single-exposure full Stokes polarization imaging with multi-wavelength compatibility.

[0014] The broadband collimated light source is a broadband collimated plane wave light source used to output broadband collimated plane waves to illuminate the target. The broadband collimated light source has strong spatial coherence and weak temporal incoherence characteristics, and supports multi-wavelength illumination in the 500~700nm band.

[0015] The two-dimensional orthogonal Ronchi grating is an amplitude-type binary grating with periodic fringe structures in both the horizontal and vertical directions. The period d of the periodic fringe structure is consistent in both the horizontal and vertical directions, and the duty cycle is 0.5. It is used to copy and shift the original spectrum of the target to two or more diffraction directions, retaining only the ±1st order diffraction spectrum components for subsequent polarization modulation.

[0016] The customized decoupled polarization modulation mask includes a hollowed-out stainless steel substrate, three achromatic linear polarizers, one achromatic left-handed circular polarizer, and a quartz delay film.

[0017] The hollow stainless steel substrate is prepared by laser cutting, allowing only ±1 order diffraction spectrum components to pass through, while the other orders are blocked; the hollow stainless steel substrate includes 4 diffraction order light-passing holes.

[0018] The three achromatic linear polarizers have polarization orientations of 0°, 90°, and 135°, respectively. They operate in the wavelength range of 400~700nm, have an extinction ratio of 5000:1, and a thickness of 0.17mm. They correspond to the three diffraction order light-transmitting apertures that are attached to the hollowed-out stainless steel substrate.

[0019] The achromatic left-handed circular polarizer operates in the wavelength range of 400~700nm, has an extinction ratio of 1200:1, a thickness of 0.17mm, and is attached to the remaining one diffraction order light-transmitting aperture on the hollowed-out stainless steel substrate.

[0020] The quartz delay plate is a 1mm thick high-transmittance quartz glass sheet, which is pasted on the back side of the diffraction order light-transmitting aperture position corresponding to the 0° and 90° achromatic linear polarizers. It is used to introduce light delay into the channel and realize time decoupling of the channel formed by the four diffraction order light-transmitting aperture positions.

[0021] The imaging detector is a grayscale imaging camera that can acquire the encoded intensity image in a single shot and separate the polarization components of different spatial frequencies in the frequency domain through digital fast Fourier transform to complete the decoding.

[0022] During the decoding process, a two-dimensional fast Fourier transform is performed on the acquired single-frame intensity image. A bandpass filter is set to extract the frequency components corresponding to the four polarization channels in the frequency domain. Inverse Fourier transforms are then performed on each of these components to separate the original image of the four polarization components.

[0023] The present invention also provides a multi-wavelength compatible single-exposure all-Stokes polarization imaging method implemented according to the device, comprising the following steps:

[0024] Step 1: Illuminate the target obj(x,y) using a broadband collimated light source. The target light passes through a first lens, an aperture, and a second lens, and is incident on a two-dimensional orthogonal Rownchi grating g(x,y) located on the object plane of the 4F system, completing the spatial spectrum replication and shift. The original spectrum of the target is copied to two or more diffraction directions, calculated using the following formula:

[0025] ,

[0026] ;

[0027] Where rect is a rectangular function, comb is a comb function; x is the spatial abscissa, y is the spatial ordinate; a and b are the grating fringe duty cycles; d is the grating period; in the device... ; This represents the spatial distribution of the target after modulation by a two-dimensional orthogonal Ronche grating. Indicates the convolution symbol;

[0028] Step 2: After the optical Fourier transform is completed by the third lens of the 4F optical system, the copied spectral components are obtained. A custom-designed decoupled polarization modulation mask is incident on the Fourier plane, and each spectral component passes through a corresponding achromatic polarization analyzer. Polarization analysis was completed, and a quartz delay plate introduced optical delay into some channels, achieving time decoupling between channels; the calculation formula is as follows:

[0029] ;

[0030] in, is the impulse function; u and v represent spatial frequency coordinates; OD represents the optical delay operation in the mask; P0, P90, P135, and LCP correspond to 0°, 90°, 135°, and the left-hand circular polarization component, respectively. The expression representing the replicated spectral components after passing through a custom decoupled polarization modulation mask;

[0031] Step 3: After the inverse optical Fourier transform is completed by the second lens of the 4F optical system, the imaging detector acquires the encoded intensity image in a single acquisition. The modulation information of four polarization channels—90°, 0°, 135°, and left-handed—is superimposed, and is represented as follows: , , and The expression is:

[0032] ;

[0033] in, The modulation coefficient represents the diffraction order (1, 0); The modulation coefficients represent the diffraction order (0, 1); The modulation coefficient represents the diffraction order (1, 1); The modulation coefficients represent the diffraction order (1, -1); they can be expressed by the formula... The calculation yields the result, where sinc is the Singer function expression; m and n take values ​​of 1, -1, and 0.

[0034] Step 4: Perform a digital fast Fourier transform on the acquired single-frame image to extract the different spatial frequency components corresponding to the four polarization channels in the frequency domain. Then, perform an inverse Fourier transform on each component to separate the original images of the four polarization components. The calculation formula is as follows:

[0035] ;

[0036] Wherein, SF represents digital signal processing of four diffraction orders by digital frequency domain bandpass filtering, including digital fast Fourier transform, clipping, and digital fast inverse Fourier transform; The result of the inverse Fourier transform includes four polarization channels: 0°, 90°, 135°, and a left-handed decoding component, denoted as follows: , ;

[0037] Step 5, based on the pre-calibrated single-point Stokes response during the mask fabrication stage, i.e., the calibrated single-point Stokes response of the LHCP (Left-handed circular polarizers) region in the mask [m 01 ,m 02 ,m 03 ], where m 01 ,m 02 ,m 03 It can be directly read from the single-point polarization measurement instrument used in the pre-calibration stage; for example, the instrument response vector at 633nm is [m 01 ,m 02 ,m 03 = [1,0,0.34,-0.94], correct and reconstruct the left-hand circular polarization component image, denoted as ILCP, to obtain the true S3 component, and finally calculate the full Stokes vector image, that is, four vector images: S0, S1, S2, and S3.

[0038] In step 2, the time decoupling introduces optical delay for the 0° and 90° polarization channels by using a quartz delay plate. By utilizing the finite temporal coherence of the light source, the light from the 0° and 90° polarization channels is made temporally incoherent with the light from the 135° and left-hand circularly polarized channels, thereby eliminating spatial frequency crosstalk between the four channels.

[0039] In step 5, the parameters are calculated using the following formula:

[0040] ,

[0041] ,

[0042] ,

[0043] ,

[0044] .

[0045] In step 5, the pre-calibration process only requires a single measurement of the Stokes response of the left-handed circularly polarized region in the mask during the mask fabrication stage to complete the calibration of the entire system. There is no need to recalibrate the system-level polarization measurement matrix for different wavelengths.

[0046] In step 5, the reconstruction errors of linear polarization parameter images S1 and S2 are less than 0.5%, while the reconstruction error of circular polarization parameter image S3 is 1.25% at a wavelength of 532nm and 0.83% at a wavelength of 633nm.

[0047] Compared with the prior art, the present invention has the following beneficial effects:

[0048] (1) This invention has excellent multi-wavelength compatibility characteristics. Through the spectrum replication mechanism of achromatic polarization device and 4F optical system, the spectrum shift of different wavelengths will not affect the polarization modulation and decoding process, and can support multi-wavelength imaging in the 500~700nm band.

[0049] (2) The present invention greatly simplifies the calibration process. There is no need to perform traditional system-level polarization measurement matrix calibration. Only the single-point Stokes response of the mask needs to be measured during the mask fabrication stage, which greatly reduces the threshold for use and the complexity of operation.

[0050] (3) This invention achieves complete decoupling of the four polarization channels through a time-delay strategy, eliminating spatial frequency crosstalk between channels. The decoding process only requires a simple Fast Fourier Transform, resulting in low computational complexity and high imaging accuracy. Experimental results show that the reconstruction errors of linear polarization parameters S1 and S2 are only 0.26% and 0.45%, respectively, while the error of circular polarization parameter S3 is 1.25% at 532nm and 0.83% at 633nm, demonstrating extremely high reconstruction accuracy.

[0051] (4) The device of this invention has a simple structure, standardized mask fabrication process, high repeatability, and does not require complex optical path alignment. The mask can be placed near the Fourier plane, making it easy to implement and promote. It can provide reliable technical support for various broadband and multi-wavelength polarization imaging scenarios. Theoretically, with the development of high-performance achromatic left-handed circular polarization devices, this system can further realize completely uncalibrated broadband full Stokes imaging, possessing broad upgrade potential. Attached Figure Description

[0052] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments, and the advantages of the present invention in the above and / or other aspects will become clearer.

[0053] Figure 1 This is a schematic diagram of a multi-wavelength compatible single-exposure all-Stokes polarization imaging device according to an embodiment of the present invention.

[0054] Figure 2 This is a physical diagram and a schematic diagram of the specific physical dimensions of the customized decoupled polarization modulation mask used in an embodiment of the present invention.

[0055] Figure 3 This is a schematic diagram of the decoding results for the four polarization components: 0°, 90°, 135°, and left-handed polarization.

[0056] Figure 4 It is based on Figure 3 The full Stokes vector diagram is calculated from the decoding results of the four polarization components. Detailed Implementation

[0057] like Figure 1 As shown, this embodiment of the invention provides a multi-wavelength compatible single-exposure full Stokes polarization imaging device, including a broadband collimated LED light source, a filter, an object under test, a first lens 1, an aperture, a second lens 2, a two-dimensional orthogonal Ronche grating, a 4F optical system, a custom decoupled polarization modulation mask, and a grayscale camera imaging detector.

[0058] The object to be tested is positioned on the front focal plane of the first lens 1;

[0059] The aperture is positioned at the rear focal plane of the first lens 1;

[0060] The distance between the second lens 2 and the aperture stop is one focal length of the second lens 2;

[0061] The two-dimensional orthogonal Ronchi grating is disposed on the back focal plane of the second lens 2;

[0062] The 4F optical system includes a third lens 3 and a fourth lens 4;

[0063] The two-dimensional orthogonal Ronchi grating is disposed on the object plane of the 4F optical system;

[0064] The customized decoupled polarization modulation mask is set in or near the Fourier plane of the 4F optical system.

[0065] The units work together to achieve single-exposure full Stokes polarization imaging with multi-wavelength compatibility.

[0066] The device provided in this embodiment operates in the 500-700nm wavelength range and can achieve full Stokes polarization imaging in a single exposure. The specific structure and implementation process are as follows:

[0067] 1. Device setup and component fabrication;

[0068] like Figure 2 As shown, the core of this device is a custom-designed decoupled polarization modulation mask. 0.7 indicates the radius of the light-passing aperture is 0.7 mm, and 1.5 indicates the center-to-center distance between the two light-passing apertures is 1.5 mm. The fabrication steps are as follows:

[0069] (1) Substrate preparation: A 0.1mm thick stainless steel sheet is used to prepare a hollow mask substrate by laser cutting. Only 4 ±1 order diffraction apertures are retained, and the rest of the area is blocked. The size of the apertures matches the spatial size of the diffraction order.

[0070] (2) Polarizer bonding: Three achromatic linear polarizers were fabricated with a working wavelength range of 400~700nm, an extinction ratio of 5000:1, a thickness of 0.17mm, and polarization orientations of 0°, 90°, and 135°, respectively. Simultaneously, an achromatic left-handed circular polarizer was fabricated with a working wavelength range of 400~700nm, an extinction ratio of 1200:1, and a thickness of 0.17mm. The four polarizers were cut to sizes matching the apertures and bonded sequentially to the four aperture positions on the substrate. During bonding, the polarization state of the transmitted light was monitored in real time using a polarimeter to ensure alignment accuracy.

[0071] (3) Delay plate bonding: A 1mm thick high-transmittance quartz glass plate is bonded behind the light-passing holes corresponding to the 0° and 90° polarizers. The quartz plate is an isotropic medium, which can introduce light delay for the light in these two channels. By utilizing the finite time coherence of the light source, the light in these two channels is out of time with the light in the 135° left-hand circular polarization channel, thereby eliminating crosstalk between channels.

[0072] In the device, the two-dimensional orthogonal Ronchi grating is an amplitude-type binary grating with a period d of 0.1 mm and a duty cycle of 0.5 in both directions, and is placed on the object plane of the 4F optical system. The 4F optical system consists of two achromatic lenses with a focal length of 200 mm. A custom polarization mask is placed 0.5 mm in front of the Fourier plane, which can realize the modulation function without precise alignment. The imaging detector is a grayscale camera with a pixel size of 5.5 μm.

[0073] 2. Imaging and decoding process;

[0074] During operation, the broadband collimated light source outputs a collimated plane wave that illuminates the target through a filter corresponding to the desired wavelength. The transmitted light from the target is incident on a Ronche grating on the object plane. The grating spatially modulates the target light, replicating and shifting the target's spatial spectrum to multiple diffraction directions. After Fourier transform by the first lens of the 4F optical system, four ±1 order replicated spectra are incident on the four apertures of the polarization mask, respectively completing polarization analysis.

[0075] Subsequently, an inverse Fourier transform is performed through a second lens, and the camera acquires an encoded intensity image in a single exposure. In this image, the information from the four polarization channels is modulated onto different spatial frequencies, and due to time decoupling, there is no crosstalk between channels. A two-dimensional fast Fourier transform is performed on the acquired image to extract the four frequency components corresponding to different channels in the frequency domain. Inverse Fourier transforms are then performed on each component to separate the images of the four polarization components: P0, P90, P135, and PLCP, I0, I... 90 I 135 I LCP .

[0076] 3. Calibration and full Stokes reconstruction;

[0077] During the mask fabrication stage, calibration can be completed by measuring the single-point Stokes response of the left-handed circularly polarized region in the mask once. During subsequent imaging, the four separated polarization components are compensated based on this pre-calibrated response, allowing the calculation of the full Stokes vectors S0, S1, S2, and S3.

[0078] To verify the effectiveness of this invention, this embodiment tested targets with different polarization complexities, including the polarization-sensitive letter NJU, a second-order vortex waveplate, birefringent plastic, and birefringent rock slices, such as... Figure 3 ( Figure 3 The first column is the coded image captured by the camera; a~e represent five types of target objects to be tested; I0, I 90 I 135 I LCP (representing the images of the four polarization components obtained from decoding) and Figure 4 As shown in the figure. GT represents the target ground truth, and a~e represent the corresponding decoding results. Experimental results demonstrate that the reconstruction accuracy of this invention is excellent: the reconstruction error for linear polarization parameter S1 is 0.26%, and for S2 it is 0.45%; the reconstruction error for circular polarization parameter S3 is 1.25% at 532nm wavelength and 0.83% at 633nm wavelength, fully verifying the reliability and multi-wavelength compatibility of this invention.

[0079] This invention provides a multi-wavelength compatible single-exposure all-Stokes polarization imaging device and method. Many methods and approaches exist for implementing this technical solution; the above description is merely a preferred embodiment of the invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of this invention, and these improvements and modifications should also be considered within the scope of protection of this invention. All components not explicitly stated in this embodiment can be implemented using existing technologies.

Claims

1. A multi-wavelength compatible single-exposure all-Stokes polarization imaging device, characterized in that, It includes a broadband collimated LED light source, a filter, an object under test, a first lens (1), an aperture, a second lens (2), a two-dimensional orthogonal Ronche grating, a 4F optical system, a custom decoupled polarization modulation mask, and a grayscale camera imaging detector. The object to be tested is positioned on the front focal plane of the first lens (1); The aperture is positioned at the rear focal plane of the first lens (1); The distance between the second lens (2) and the aperture stop is one focal length of the second lens (2); The two-dimensional orthogonal Ronchi grating is disposed on the back focal plane of the second lens (2); The 4F optical system includes a third lens (3) and a fourth lens (4); The two-dimensional orthogonal Ronchi grating is set on the object plane of the 4F optical system to modulate the spatial distribution of the incident target light, realize the replication and shift of the spectrum, generate multiple sets of replicated spectral components in the Fourier plane, and retain only 4 sets of ±1 order diffraction spectral components for subsequent processing. The first set is (0, +1) and (0, -1); the second set is (+1, 0) and (-1, 0); the third set is (+1, +1) and (-1, -1); and the fourth set is (-1, +1) and (+1, -1). The customized decoupled polarization modulation mask is set in or near the Fourier plane of the 4F optical system to perform polarization analysis on the four retained ±1st order diffraction spectrum components, corresponding to four polarization channels: 0°, 90°, 135°, and left-handed circular polarization. The decoupling of the four polarization channels is achieved through a time-optical delay strategy to eliminate crosstalk between channels. The imaging detector is used to acquire the encoded intensity image output by the 4F optical system in a single exposure. The four polarization components are separated by digital fast Fourier transform decoding, and the full Stokes vector image is reconstructed based on the pre-calibrated single-point response.

2. The apparatus according to claim 1, characterized in that, The broadband collimated light source is a broadband collimated plane wave light source, used to output broadband collimated plane waves to illuminate the target.

3. The apparatus according to claim 2, characterized in that, The two-dimensional orthogonal Ronchi grating is an amplitude-type binary grating with periodic fringe structures in both the horizontal and vertical directions. The period d of the periodic fringe structure is consistent in both the horizontal and vertical directions. It is used to copy and shift the original spectrum of the target to more than two diffraction directions, retaining only the ±1st order diffraction spectrum components for subsequent polarization modulation.

4. The apparatus according to claim 3, characterized in that, The customized decoupled polarization modulation mask includes a hollowed-out stainless steel substrate, three achromatic linear polarizers, one achromatic left-handed circular polarizer, and a quartz delay film. The hollowed-out stainless steel substrate is prepared by laser cutting, allowing only ±1 order diffraction spectrum components to pass through; the hollowed-out stainless steel substrate includes 4 diffraction order light-transmitting apertures. The polarization orientations of the three achromatic linear polarizers are 0°, 90°, and 135°, respectively, which correspond to the three diffraction order light-transmitting apertures attached to the hollowed-out stainless steel substrate. The achromatic left-handed circular polarizer is attached to the remaining one diffraction order light-transmitting aperture of the hollowed-out stainless steel substrate. The quartz delay plate is a high-transmittance quartz glass sheet, which is pasted on the back side of the diffraction order light-transmitting aperture position corresponding to the 0° and 90° achromatic linear polarizers. It is used to introduce light delay into the channel and realize the time decoupling of the channel formed by the four diffraction order light-transmitting aperture positions.

5. The apparatus according to claim 4, characterized in that, The imaging detector is a grayscale imaging camera that can acquire encoded intensity images in a single exposure and separate polarization components of different spatial frequencies in the frequency domain through digital fast Fourier transform to complete the decoding.

6. A method for multi-wavelength compatible single-exposure full Stokes polarization imaging implemented by the apparatus according to any one of claims 1 to 5, characterized in that, Includes the following steps: Step 1: Illuminate the target obj(x,y) using a broadband collimated light source. The target light passes through the first lens (1), the aperture, and the second lens (2), and is incident on the two-dimensional orthogonal Rownchi grating g(x,y) located on the object plane of the 4F system, completing the spatial spectrum replication and shift. The original spectrum of the target is copied to two or more diffraction directions, and the calculation formula is as follows: ， ； Where rect is a rectangular function, comb is a comb function; x is the spatial abscissa, y is the spatial ordinate; a and b are the grating fringe duty cycles; and d is the grating period. This represents the spatial distribution of the target after modulation by a two-dimensional orthogonal Ronche grating. Indicates the convolution symbol; Step 2, after the optical Fourier transform is completed by the third lens (3) of the 4F optical system, the copied spectral components are obtained. A custom-designed decoupled polarization modulation mask is incident on the Fourier plane, and each spectral component passes through a corresponding achromatic polarization analyzer. Polarization analysis was completed, and a quartz delay plate introduced optical delay into some channels, achieving time decoupling between channels; the calculation formula is as follows: ； in, is the impulse function; u and v represent spatial frequency coordinates; OD represents the optical delay operation in the mask; P0, P90, P135, and LCP correspond to 0°, 90°, 135°, and the left-hand circular polarization component, respectively. The expression representing the replicated spectral components after passing through a custom decoupled polarization modulation mask; Step 3: After the inverse Fourier transform is completed by the second lens of the 4F optical system, the imaging detector acquires the encoded intensity image in a single exposure. The modulation information of four polarization channels—90°, 0°, 135°, and left-handed—is superimposed, and is represented as follows: , , and The expression is: ； in, The modulation coefficient represents the diffraction order (1, 0); The modulation coefficients represent the diffraction order (0, 1); The modulation coefficient represents the diffraction order (1, 1); The modulation coefficients represent the diffraction order (1, -1); they can be expressed by the formula... The calculation yields the result, where sinc is the Singer function expression; m and n take values ​​of 1, -1, and 0. Step 4: Perform a digital fast Fourier transform on the acquired single-frame image to extract the different spatial frequency components corresponding to the four polarization channels in the frequency domain. Perform inverse Fourier transforms on each component to separate the original images of the four polarization components. The calculation formula is as follows: ； Wherein, SF represents digital signal processing of four diffraction orders by digital frequency domain bandpass filtering, including digital fast Fourier transform, clipping, and digital fast inverse Fourier transform; The result of the inverse Fourier transform includes four polarization channels: 0°, 90°, 135°, and a left-handed decoding component, denoted as follows: , ; Step 5, pre-calibration of single-point Stokes response based on mask-making stage, i.e. the calibrated single-point Stokes response [m 01 ,m 02 ,m 03 ] of the LHCP area in the mask plate; correct the reconstructed left-handed circularly polarized component image, denoted as ILCP, to obtain the real S3 component, and finally calculate the full Stokes vector image, i.e. 4 vector images of S0, S1, S2 and S3.

7. The method according to claim 6, characterized in that, In step 2, the time decoupling introduces optical delay for the 0° and 90° polarization channels by using a quartz delay plate. By utilizing the finite temporal coherence of the light source, the light from the 0° and 90° polarization channels is made temporally incoherent with the light from the 135° and left-hand circularly polarized channels, thereby eliminating spatial frequency crosstalk between the four channels.

8. The method according to claim 7, characterized in that, In step 5, the parameters are calculated using the following formula: ， ， ， ， 。 9. The method according to claim 8, characterized in that, In step 5, the pre-calibration process only requires a single measurement of the Stokes response of the left-handed circularly polarized region in the mask during the mask fabrication stage to complete the calibration of the entire system.

10. The method according to claim 9, characterized in that, In step 5, the reconstruction errors of linear polarization parameter images S1 and S2 are less than 0.5%, while the reconstruction error of circular polarization parameter image S3 is 1.25% at a wavelength of 532nm and 0.83% at a wavelength of 633nm.

Images