空间调制傅里叶变换斯托克斯偏振光谱仪

Abstract

本发明提供一种空间调制傅里叶变换斯托克斯偏振光谱仪，包括：望远系统、偏振调制系统、偏振干涉系统和成像系统；目标场景发出的目标光场入射至所述望远系统中，经过所述望远系统后所述目标光场被准直为平行光场入射至所述偏振调制系统；所述平行光场经过所述偏振调制系统后得到线偏振光场入射至所述偏振干涉系统；所述线偏振光场经过所述偏振干涉系统形成具有特定光程差分布特点的偏振干涉光场；所述偏振干涉光场入射至所述成像系统形成偏振干涉图；对所述偏振干涉图阵列进行斯托克斯通道滤波，并进行傅里叶变换，同时解调出所述目标光场各斯托克斯参量的光谱信息。解决了偏振光谱多维信息实时测量的问题。

Description

Technical Field

[0001] This invention relates to the field of spectroscopy, and in particular to a spatially modulated Fourier transform Stokes polarization spectrometer. Background Technology

[0002] With the development of science and technology, high-tech fields such as space exploration, military reconnaissance, medical engineering, and resource remote sensing are placing increasingly higher demands on the accuracy and real-time performance of target detection and identification. Therefore, combining spectral and polarization techniques to construct multi-dimensional real-time information detection systems has become a pressing application requirement. Infrared polarization spectral information is characterized by its all-weather capability and independence from day-night variations, offering unique advantages in complex environments. Fourier transform spectroscopy, with its advantages of multi-channel operation, high throughput, high wavenumber accuracy, and low stray light, enables high-resolution detection and analysis of weak radiators, making it the most powerful spectral detection technology in the infrared band. However, traditional Fourier transform infrared spectroscopy is limited in reliability, stability, and real-time performance due to its moving mirror scanning mechanism. Therefore, infrared polarization spectroscopy based on static interferometry systems has greater development potential and significant application value.

[0003] Current polarization spectroscopy detection technology is in a phase of rapid development. Most polarization spectroscopy detection systems employ time-division or amplitude-division detection methods, splitting the system into multiple polarization detection channels through polarizer rotation or beam splitters. Time-division detection cannot acquire transient information in all dimensions in real time, while amplitude-division detection results in a very large system size and weight. Furthermore, current research primarily focuses on the visible light band, with relatively little research conducted in the infrared band. Summary of the Invention

[0004] In view of the above problems, the purpose of this invention is to propose a spatially modulated Fourier transform Stokes polarization spectrometer, which combines Fourier transform spectroscopy with polarization modulation technology to simultaneously acquire the spectral and polarization information of a target. Phase modulation is performed using an interferometric system based on multi-stage micromirrors, eliminating moving parts and improving system reliability and real-time information acquisition. Polarization modulation is performed using a high-order phase delayer, eliminating the need for amplitude division and reducing the system's size and weight. This instrument can achieve integrated acquisition of multi-dimensional spectral and polarization information, while also possessing miniaturization, multi-parameter capabilities, static detection, and snapshot detection performance.

[0005] To achieve the above objectives, the present invention adopts the following specific technical solution:

[0006] This invention provides a spatially modulated Fourier transform Stokes polarization spectrometer, comprising: a telescope system, a polarization modulation system, a polarization interferometry system, and an imaging system;

[0007] The target light field emitted from the target scene is incident on the telescope system. After passing through the telescope system, the target light field is collimated into a parallel light field and incident on the polarization modulation system.

[0008] The polarization modulation system includes: a first higher-order phase delayer, a second higher-order phase delayer, and a polarizer polarizer;

[0009] The parallel light field is polarized by passing through the first higher-order phase delayer and the second higher-order phase delayer in sequence to obtain the modulated light field. The modulated light field then passes through the polarizer polarizer to obtain the linearly polarized light field, which is then incident on the polarization interference system.

[0010] The polarization interference system includes: a beam splitter, a transverse multi-stage micromirror, and a longitudinal multi-stage micromirror;

[0011] The linearly polarized light field is decomposed into reflected beams and transmitted beams of equal amplitude by a beam splitter and then incident on the transverse multi-stage micro-reflector and the longitudinal multi-stage micro-reflector, respectively.

[0012] The reflected beam and the transmitted beam are respectively incident into the transverse multi-stage micro-reflector and the longitudinal multi-stage micro-reflector, respectively, and generate transverse phase modulation and longitudinal phase modulation. After returning to the beam splitter along the original path, the reflected beam and the transmitted beam are emitted through the beam splitter and generate superimposed interference at the exit position of the beam splitter to form a polarization interference light field with specific optical path difference distribution characteristics.

[0013] A polarization interference light field is incident on the imaging system to form a polarization interference pattern;

[0014] Stokes channel filtering is applied to the polarization interferogram array, followed by Fourier transform, and the spectral information of each Stokes parameter of the target optical field is demodulated.

[0015] Preferably, the telescope system includes: a telescope objective lens, a field stop, and a collimating lens;

[0016] The target light field is imaged at the field stop after passing through the telescope objective lens;

[0017] The field stop is located on the image-side focal plane of the telescope objective and simultaneously on the object-side focal plane of the collimating lens. It is used to limit the field of view of the image of the target scene formed by the telescope objective. The imaging light field through the field stop is collimated into a parallel light field by the collimating lens.

[0018] Preferably, the fast axis of the first higher-order phase delay is along the positive x-axis, and the slow axis is along the positive y-axis;

[0019] The fast axis of the second higher-order phase delayer makes an angle of 45° with the positive x-axis, and the slow axis makes an angle of 135° with the positive x-axis.

[0020] The first and second higher-order phase retarders are birefringent crystals used to adjust the phase difference of the outgoing light; their materials are quartz, calcite, magnesium fluoride, yttrium vanadate, or barium metaborate.

[0021] The transmission axis of the polarizer polarizer is along the x-axis, and it is used to transmit linearly polarized light with a specific vibration direction.

[0022] Preferably, after the parallel light field passes through the polarization modulation system, all of its Stokes parameters S0, S1, S2, and S3 are modulated into the intensity parameter S0 component, thereby allowing the polarization state of the target light field to be detected.

[0023] set up:

[0024] The Stokes vector of the target light field is S in The Mueller matrix of the first higher-order phase delay is M. R1 The Mueller matrix of the second higher-order phase delay is M. R2 The Mueller matrix of the polarizer polarizer is M. P ;

[0025] set up:

[0026] The wavenumber of the target light field is ν, and the refractive indices of the o-ray and e-ray of the first and second higher-order phase retarder crystals are n and n, respectively. o and n e The thickness of the first higher-order phase delay is d1, and the thickness of the second higher-order phase delay is d2;

[0027] The optical path difference of the first higher-order phase retarder is L1 = (n e -n o )d1, the phase delay is

[0028]

[0029] The optical path difference of the second higher-order phase retarder is L2 = (n e -n o )d2, the phase delay is

[0030]

[0031] Stokes parameter S of the linearly polarized light field obtained after the target light field passes through the polarization modulation system out for:

[0032]

[0033] Therefore, the S0' parameter in the linearly polarized optical field contains all the Stokes parameters of the target optical field, and each parameter is modulated by a different modulation function, that is:

[0034]

[0035] Preferably, the transverse multi-stage micromirrors and the longitudinal multi-stage micromirrors have a stepped structure, are placed in mirror image with respect to the beam splitting surface of the beam splitter, and the step directions are orthogonal to each other.

[0036] The transverse multi-stage micromirror is located in the reflected light path of the beam splitter, and its stepped structure is along the x-axis.

[0037] The longitudinal multi-stage micro-mirrors are located in the transmission light path of the beam splitter, and their stepped structure is along the y-axis.

[0038] The transverse multi-stage micromirror and the longitudinal multi-stage micromirror utilize their stepped structure to perform distributed phase modulation on the incident beam in two directions, respectively.

[0039] Preferably, the imaging system includes: a beam-shrinking system and an area array detector;

[0040] The beam-shrinking system is a telecentric optical path structure used to image the polarization interference light field onto the area array detector; the area array detector is used to receive the polarization interference image array.

[0041] After passing through the beam-shrinking system, the linearly polarized light field forms a polarization interference image array on the area array detector.

[0042] Preferably, let:

[0043] The number of steps in the transverse and longitudinal multi-stage micromirrors is N, and the step height of one of the multi-stage micromirrors is h1; then the step height of the other multi-stage micromirror is h2 = N × h1. Therefore, the optical path difference Δ and phase difference φ corresponding to the interference optical field unit formed by the m-th step of the first multi-stage micromirror and the n-th step of the other multi-stage micromirror are respectively:

[0044] Δ(m,n)=2nh2-2mh1=2(nN-m)h1

[0045]

[0046] Since the signal acquired by the area array detector is the total intensity signal of the outgoing light, the final interferogram signal I acquired by the area array detector is:

[0047]

[0048] Preferably, the interferogram signal I is expanded using Euler's formula, then the target light field interferogram signal I is:

[0049]

[0050] The Stokes parametric interferogram signal of the target light field was modulated into a signal with 0, and The seven parts centered on the center will form an interferogram with seven channels, as shown below:

[0051] The center of the C0 interferogram channel is located at Δ = 0, containing only the S0 parameter;

[0052] The center of the C1 interferogram channel is located at Δ = L2 and contains only the S1 parameter;

[0053] The center of the C2 interferogram channel is located at Δ = L2 - L1, and includes parameters S2 and S3.

[0054] The center of the C3 interferogram channel is located at Δ = L2 + L1, and includes parameters S2 and S3.

[0055] C -1 The center of the interferogram channel is located at Δ = -L2, and contains only the S1 parameter;

[0056] C -2 The center of the interferogram channel is located at Δ = -(L2 - L1), which includes parameters S2 and S3;

[0057] C -3 The center of the interferogram channel is located at Δ = -(L2 + L1), which includes parameters S2 and S3;

[0058] The passband of the bandpass filter in the C0 interferogram channel is located at Δ = [-(L2-L1) / 2, (L2-L1) / 2]. After Fourier transform, the spectrum of the S0 parameter is obtained as: S0(ν) = 2FT[C0(Δ)];

[0059] The passband of the bandpass filter in the C1 interferogram channel is located at Δ=[(2L2-L1) / 2,(2L2+L1) / 2], and the spectrum of the S1 parameter obtained by Fourier transform is: S1(ν)=4FT[C1(Δ)]exp(j2πνL2);

[0060] The passband of the bandpass filter in the C2 interferogram channel is located at Δ = [(L2-L1) / 2, (2L2-L1) / 2]. After Fourier transform, the spectra of parameters S2 and S3 are obtained as follows:

[0061] S2(ν)=8Re{FT[C2(Δ)]exp[j2πν(L2-L1)]};

[0062] S3(ν)=-8Im{FT[C2(Δ)]exp[j2πν(L2-L1)]};

[0063] Each channel contains one or two Stokes parameters; the C0 channel contains only the S0 parameter. ±1The channel contains only the S1 parameter, C ±2 and C ±3 The channel contains parameters S2 and S3, and the center positions of the interferogram channels are located at 0, ±L2, ±(L2-L1), and ±(L2+L1), respectively.

[0064] Preferably, when the thickness ratio of the two higher-order phase retarders is d1:d2 = 1:2, the seven channels C0, C1, C2, and C3 of the interferogram are... ±1 C ±2 C ±3 Separating the signals, three independent channels were selected to perform Fourier transforms on the interferogram signals, thereby obtaining the spectral information of the four Stokes parameters of the target light field:

[0065] S0(ν)=2FT[C0(Δ)]

[0066]

[0067]

[0068]

[0069] Compared with existing technologies, this invention employs a high-order phase retarder based on a birefringent crystal for polarization modulation, ensuring that all Stokes parameters of the incident light field are modulated into the light intensity signal. Simultaneously, it utilizes spatial phase modulation technology based on multi-level micromirrors to achieve synchronous acquisition of interference light intensity signals at all interference orders, resulting in a spatially distributed interferometric image array. The combination of Stokes polarization modulation and interferogram spatial phase modulation instantaneously acquires the Stokes channel interferogram. By performing channel filtering and Fourier transform on this interferogram, synchronous measurement of multidimensional polarization spectral information of the Stokes parameters is achieved, improving the real-time performance of information acquisition. This solves the problem of real-time measurement of multidimensional polarization spectral information. Attached Figure Description

[0070] Figure 1 This is a schematic diagram of the optical path of a spatially modulated Fourier transform Stokes polarization spectrometer provided according to an embodiment of the present invention.

[0071] Figure 2 This is a schematic diagram of the crystal optical features of a first higher-order phase delayer provided according to an embodiment of the present invention.

[0072] Figure 3 This is a schematic diagram of the crystal optical features of a second higher-order phase delayer provided according to an embodiment of the present invention.

[0073] Figure 4 This is a schematic diagram of the crystal optical characteristics of a polarizer polarizer provided according to an embodiment of the present invention.

[0074] Figure 5 This is a schematic diagram of the structure of a multi-level micromirror provided according to an embodiment of the present invention.

[0075] Figure 6 This is a schematic diagram of the optical path difference modulation process of a multi-stage micromirror according to an embodiment of the present invention.

[0076] Figure 7 This is a schematic diagram of Stokes channel interference provided according to an embodiment of the present invention.

[0077] Figure 8 This is a schematic diagram of the Stokes parametric spectral demodulation process provided in an embodiment of the present invention.

[0078] The reference numerals in the figures include: telescope objective 1, field stop 2, collimating lens 3, first higher-order phase retarder 4, second higher-order phase retarder 5, polarizer 6, beam splitter 7, lateral multi-stage micromirror 8, longitudinal multi-stage micromirror 9, beam shrinking system 10 and area array detector 11.

[0079] Interference light fields R1, R2, R3, R4, R5, R6, R7, R8 and R9. Detailed Implementation

[0080] In the following description, embodiments of the invention will be described with reference to the accompanying drawings. In the description below, the same modules are denoted by the same reference numerals. Where the same reference numerals are used, their names and functions are also the same. Therefore, their detailed description will not be repeated.

[0081] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and do not constitute a limitation thereof.

[0082] Figure 1 The optical path of a spatially modulated Fourier transform Stokes polarization spectrometer provided according to an embodiment of the present invention is shown.

[0083] like Figure 1 As shown, the spatially modulated Fourier transform Stokes polarization spectrometer provided in this embodiment of the invention includes: a telescope system, a polarization modulation system, a polarization interferometry system, and an imaging system.

[0084] The target light field emitted from a distant target scene first enters the telescope system. The polarization state of the target light field is determined by the polarization characteristics of the target scene. Target light fields emitted from different target scenes have different polarization characteristics. After passing through the telescope system, the target light field is collimated into a parallel light field.

[0085] The telescope system includes: a telescope objective lens 1, a field stop 2, and a collimating lens 3. The target light field, after passing through the telescope objective lens 1, is imaged at the field stop 2. The field stop 2 is located on the image-side focal plane of the telescope objective lens 1 and simultaneously on the object-side focal plane of the collimating lens 3. It is used to limit the field of view of the image of the target scene formed by the telescope objective lens 1. The imaged light field through the field stop 2 is collimated into a parallel light field by the collimating lens 3. The collimated parallel light field is then incident on the polarization modulation system.

[0086] Figure 2 The crystal optical features of a first high-order phase delayer provided according to an embodiment of the present invention are shown.

[0087] Figure 3 The crystal optical features of a second higher-order phase delayer provided according to an embodiment of the present invention are shown.

[0088] Figure 4 The crystal optical features of a polarizer polarizer provided according to an embodiment of the present invention are shown.

[0089] like Figure 2-4 As shown, the polarization modulation system includes: a first higher-order phase delayer 4, a second higher-order phase delayer 5, and a polarizer polarizer 6.

[0090] The optical axis of the crystal in the first higher-order phase retarder 4 is parallel to the surface. The fast axis (e-axis) is along the positive x-axis, and the slow axis (o-axis) is along the positive y-axis. The thickness is d1. The optical path difference between the e-ray and the o-ray at the exit interface is (n e -n o )d1.

[0091] The optical axis of the crystal in the second higher-order phase retarder 5 is parallel to the surface. The angle between the fast axis (e-axis) and the positive x-axis is 45°, and the angle between the slow axis (o-axis) and the positive x-axis is 135°. The thickness is d2. The optical path difference between the e-ray and the o-ray at the exit interface is (n e -n o )d2.

[0092] The first higher-order phase retarder 4 and the second higher-order phase retarder 5 are used to adjust the phase difference of the emitted light. The materials are birefringent crystals, including quartz, calcite, magnesium fluoride, yttrium vanadate, barium metaborate (α-BBO), etc.

[0093] The polarizer polarizer 6 has its transmission axis (p-axis) along the x-axis, allowing light to pass through only in the 0° vibration direction. It is constructed by depositing a layer of micro / nano-structured metal wire grids on a substrate. The substrate material can be a dielectric such as calcium fluoride, zinc selenide, zinc sulfide, silicon, or germanium, while the wire grid material can be a metal such as gold or aluminum. Light with a polarization direction perpendicular to the wire grid direction can pass through, while light with a polarization direction parallel to the wire grid direction is blocked; that is, the wire grid direction is along the y-axis. It is used to transmit linearly polarized light in a specific vibration direction.

[0094] The parallel light field is polarized and modulated by passing through the first higher-order phase delayer 4 and the second higher-order phase delayer 5 in sequence to obtain the modulated light field, which can be decomposed into two components with mutually perpendicular vibration directions.

[0095] The modulated light field is then passed through polarizer 6 to obtain a linearly polarized light field. The vibration direction of the linearly polarized light field makes an angle of 0° with the positive x-axis.

[0096] After the parallel light field passes through the polarization modulation system, all of its Stokes parameters (S0, S1, S2, S3) are modulated into the intensity parameter S0 component, thereby enabling the polarization state of the target light field to be detected.

[0097] set up:

[0098] The Stokes vector of the target light field is S in The Mueller matrix of the first higher-order phase delay is M. R1 The Mueller matrix of the second higher-order phase delay is M. R2 The Mueller matrix of the polarizer is M. P .

[0099] set up:

[0100] The wavenumber of the target light field is ν, and the refractive indices of the o-ray and e-ray of the crystals of the first higher-order phase retarder 4 and the second higher-order phase retarder 5 are n and n, respectively. o and n e The thickness of the first higher-order phase delay 4 is d1, and the thickness of the second higher-order phase delay 5 is d2.

[0101] Then the optical path difference of the first higher-order phase retarder 4 is L1 = (n e -n o )d1, the phase delay is

[0102]

[0103] The optical path difference of the second higher-order phase retarder 5 is L2 = (n e -n o )d2, the phase delay is

[0104]

[0105] After the target light field passes through the polarization modulation system, the Stokes parameter S of the linearly polarized light field out It can be represented as:

[0106]

[0107] Therefore, the linearly polarized light field emitted from the polarization modulation system contains all the Stokes parameters of the target light field in its S0' parameter, and each parameter is modulated by a different modulation function, that is:

[0108]

[0109] A linearly polarized light field with a vibration direction at an angle of 0° to the positive x-axis is incident on a polarization interference system.

[0110] The polarization interference system includes: a beam splitter 7, a transverse multi-stage micromirror 8, and a longitudinal multi-stage micromirror 9.

[0111] The linearly polarized light field is split into two beams of equal amplitude by the beam splitter 7 and incident on the transverse multi-stage micro-reflector 8 and the longitudinal multi-stage micro-reflector 9, respectively. One beam is reflected after passing through the beam splitter 7 to form a reflected beam, and the other beam is transmitted after passing through the beam splitter 7 to form a transmitted beam.

[0112] Figure 5 The structure of a multi-stage micromirror provided according to an embodiment of the present invention is shown.

[0113] Figure 6 The optical path difference modulation process of a multi-stage micromirror provided according to an embodiment of the present invention is illustrated.

[0114] like Figure 5-6 As shown, the transverse multi-stage micromirror 8 and the longitudinal multi-stage micromirror 9 have a stepped structure, are placed in mirror image of the beam splitter 7, and the step directions are orthogonal to each other.

[0115] The transverse multi-stage micro-mirror 8 is located on the reflected light path of the beam splitter 7, and its stepped structure is along the x-axis direction;

[0116] The longitudinal multi-stage micro-mirror 9 is located on the transmission light path of the beam splitter 7, and its stepped structure is along the y-axis.

[0117] Two multi-stage micromirrors utilize their stepped structure to perform distributed phase modulation of the incident beam in two directions.

[0118] The reflected and transmitted beams are incident on the transverse multi-stage micro-reflector 8 and the longitudinal multi-stage micro-reflector 9, respectively, and undergo transverse and longitudinal phase modulation, respectively. They then return along their original paths to the beam splitter 7. Both the reflected and transmitted beams are reflected and transmitted after passing through the beam splitter 7. The two beams exiting the beam splitter 7 exhibit superposition interference at the exit position of the beam splitter 7. Due to the distributed phase modulation effect of the transverse and longitudinal multi-stage micro-reflectors 8 and 9 on the optical field, the superposition interference of the two beams forms a polarization interference optical field with specific optical path difference distribution characteristics.

[0119] The specific modulation process of the polarization interference optical field is as follows:

[0120] The interference light field R1 is the interference light field formed by the first step of the transverse multi-stage micro-reflector 8 and the first step of the longitudinal multi-stage micro-reflector 9, corresponding to the interferogram array sampling unit (1).

[0121] The interference light field R2 is the interference light field formed by the third step of the transverse multi-stage micro-reflector 8 and the first step of the longitudinal multi-stage micro-reflector 9, corresponding to the interferogram array sampling unit (3).

[0122] The interference light field R3 is the interference light field formed by the fifth step of the transverse multi-stage micro-reflector 8 and the first step of the longitudinal multi-stage micro-reflector 9, corresponding to the interferogram array sampling unit (5).

[0123] The interference light field R4 is the interference light field formed by the first step of the transverse multi-stage micro-reflector 8 and the third step of the longitudinal multi-stage micro-reflector 9, corresponding to the interferogram array sampling unit (11).

[0124] The interference light field R5 is the interference light field formed by the third step of the transverse multi-stage micro-reflector 8 and the third step of the longitudinal multi-stage micro-reflector 9, corresponding to the interferogram array sampling unit (13).

[0125] The interference light field R6 is the interference light field formed by the fifth step of the transverse multi-stage micro-reflector 8 and the third step of the longitudinal multi-stage micro-reflector 9, corresponding to the interferogram array sampling unit (15).

[0126] The interference light field R7 is the interference light field formed by the first step of the transverse multi-stage micro-reflector 8 and the fifth step of the longitudinal multi-stage micro-reflector 9, corresponding to the interferogram array sampling unit (21).

[0127] The interference light field R8 is the interference light field formed by the third step of the transverse multi-stage micro-reflector 8 and the fifth step of the longitudinal multi-stage micro-reflector 9, corresponding to the interferogram array sampling unit (23).

[0128] The interference light field R9 is the interference light field formed by the fifth step of the horizontal multi-stage micro-reflector 8 and the fifth step of the vertical multi-stage micro-reflector 9, corresponding to the interferogram array sampling unit (25).

[0129] A polarization interference light field is incident on an imaging system, which includes a beam-shrinking system 10 and an area array detector 11.

[0130] The beam-shrinking system 10 is a telecentric optical path structure used to image the polarization interference light field onto the area array detector 11. The area array detector 11 is used to receive the polarization interference image array.

[0131] After passing through the beam-shrinking system 10, the linearly polarized light field forms a polarization interference image on the array detector 11.

[0132] By applying Stokes channel filtering to the polarization interferogram array and performing Fourier transform, the spectral information of each Stokes parameter of the target optical field can be demodulated simultaneously, thereby realizing the simultaneous detection of multidimensional polarization spectral information and improving the real-time performance of information acquisition.

[0133] The process includes:

[0134] set up:

[0135] The horizontal multi-stage micro-reflector 8 and the vertical multi-stage micro-reflector 9 both have N steps. The step height of one of the multi-stage micro-reflectors is h1, where h1 ≤ λm4in. The step height of the other multi-stage micro-reflector is h2 = N × h1. Therefore, the optical path difference between the interference optical field units formed by the m-th step of the first multi-stage micro-reflector and the n-th step of the other multi-stage micro-reflector is:

[0136] Δ(m,n)=2nh2-2mh1=2(nN-m)h1

[0137] The phase difference is:

[0138] Since the signal acquired by the area array detector 11 is the total intensity signal of the emitted light, the final interferogram signal acquired by the area array detector 11 is:

[0139]

[0140] Expanding it using Euler's formula, the interferogram signal is represented as:

[0141]

[0142] Figure 7 A schematic diagram of Stokes channel interference provided according to an embodiment of the present invention is shown.

[0143] Figure 8The Stokes parametric spectral demodulation process provided according to an embodiment of the present invention is illustrated.

[0144] like Figure 7-8 As shown, after modulation by the polarization spectrometer provided by this invention, the Stokes parametric interferogram of the target light field is modulated to be 0, and The seven parts centered on the center will form an interferogram with seven channels, as shown below:

[0145] The C0 interferogram channel, centered at Δ = 0, contains only the S0 parameter;

[0146] The C1 interferogram channel, centered at Δ = L2, contains only the S1 parameter;

[0147] The C2 interferogram channel is centered at Δ = L2 - L1 and includes parameters S2 and S3.

[0148] The C3 interferogram channel is centered at Δ = L2 + L1 and contains parameters S2 and S3.

[0149] C -1 The interferogram channel, centered at Δ = -L2, contains only the S1 parameter;

[0150] C -2 The interferogram channel, centered at Δ = -(L2 - L1), contains parameters S2 and S3;

[0151] C -3 The interferogram channel, centered at Δ = -(L2 + L1), contains parameters S2 and S3;

[0152] The passband of the bandpass filter in the C0 interferogram channel is located at Δ = [-(L2-L1) / 2, (L2-L1) / 2]. After Fourier transform, the spectrum of the S0 parameter is obtained as: S0(ν) = 2FT[C0(Δ)];

[0153] The passband of the bandpass filter in the C1 interferogram channel is located at Δ=[(2L2-L1) / 2,(2L2+L1) / 2], and the spectrum of the S1 parameter obtained by Fourier transform is: S1(ν)=4FT[C1(Δ)]exp(j2πνL2);

[0154] The passband of the bandpass filter in the C2 interferogram channel is located at Δ = [(L2-L1) / 2, (2L2-L1) / 2]. After Fourier transform, the spectra of parameters S2 and S3 are obtained as follows:

[0155] S2(ν)=8Re{FT[C2(Δ)]exp[j2πν(L2-L1)]};

[0156] S3(ν)=-8Im{FT[C2(Δ)]exp[j2πν(L2-L1)]}.

[0157] Each channel contains one or two Stokes parameters; the C0 channel contains only the S0 parameter. ±1 The channel contains only the S1 parameter, C ±2 and C ±3 The channel contains parameters S2 and S3, and the center positions of the interferogram channels are located at 0, ±L2, ±(L2-L1), and ±(L2+L1), respectively.

[0158] By rationally designing the thickness ratio of the two higher-order phase delayers, when the thickness ratio is d1:d2=1:2, the seven channels (C0, C1, C2, C3, C4, C5, C6, C7, C8, C9 ... ±1 C ±2 C ±3 Separate them from each other. Then select three independent channels and perform a Fourier transform on the interferogram to obtain the spectral information of the four Stokes parameters of the target light field:

[0159] S0(ν)=2FT[C0(Δ)]

[0160]

[0161]

[0162]

[0163] This invention employs polarization modulation technology using a high-order phase delayer, combined with spatial modulation interferometry using multi-stage micromirrors, to solve the problem of synchronous measurement of multi-dimensional polarization spectral information. By utilizing the high-order phase delay technology of birefringent crystals, all Stokes parameters of the incident light field are modulated into the light intensity signal, achieving synchronous detection of Stokes parameters. Simultaneously, multi-stage micromirrors are used to perform distributed phase modulation of the polarization light field, achieving a specific distribution of the optical path difference in transverse space, thus enabling synchronous acquisition of interferometric information. Synchronous demodulation of the Stokes parameter spectrum is achieved by performing Stokes channel filtering and Fourier transform on the polarization interferogram.

[0164] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

[0165] The specific embodiments of the present invention described above do not constitute a limitation on the scope of protection of the present invention. Any other corresponding changes and modifications made in accordance with the technical concept of the present invention should be included within the scope of protection of the claims of the present invention.

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