A low cross-talk channel modulation interference polarization spectrum detection method and system

Abstract

The application relates to the technical field of optics, in particular to a low-crosstalk channel modulation interference polarization spectrum detection method and system, which comprises a half-field telescope module, a phase modulation module, an interference modulation module and a detection module; the half-field telescope module is used for collimating an input target light beam in a lower half field, the target light beam is parallelly transmitted to the phase modulation module according to a set range, a compound polarization beam splitter prism group in the phase modulation module performs a light splitting operation based on the target light beam output by the half-field telescope module, two parallel polarization lights are emitted, and independent phase modulation of the two lights is ensured; the interference modulation module is used for performing light splitting modulation according to the two polarization lights, ensuring that the two polarization light beams after modulation interfere and are transmitted to the detection module to be imaged. The system improves the detection precision of narrow-band polarization spectrum or polarization spectrum with obvious narrow-band wave peaks and narrow-band absorption peaks, and has strong polarization spectrum detection capability and wide application range.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of optical technology, and particularly relates to a low-crosstalk channel modulation interference polarization spectrum detection method and system. BACKGROUND

[0002] After light interacts with matter, its physical properties change, and optical information such as light intensity, spectrum, and polarization also changes accordingly. By detecting these optical information, the important characteristics of the target object such as the material composition and surface structure can be obtained. With the deepening of scientific research and engineering application, the traditional photoelectric detection method represented by intensity imaging cannot meet the increasingly complex detection needs, and photoelectric detection technology is developing towards the direction of multi-dimensional optical information fusion acquisition, so as to realize more accurate and comprehensive target identification. The continuous progress of photoelectric technology has significantly improved the performance of various optical elements. With these developments, multi-dimensional optical imaging technology (such as spectral imaging and polarization imaging) has also developed rapidly and has been widely used in many fields.

[0003] Spectral imaging technology can simultaneously obtain the two-dimensional spatial intensity information and one-dimensional spectral information of the target. The reflection, transmission, and radiation spectra of different target objects have their own unique characteristics, and analyzing these spectra can achieve target classification and identification. Polarization imaging technology can simultaneously obtain the two-dimensional spatial intensity information and one-dimensional polarization information of the target, and is sensitive to the roughness, surface structure, contour characteristics, and humidity of the target. The polarization characteristics of different materials differ significantly, which can effectively enhance the contour of the target and achieve material classification and identification.

[0004] Spectral information and polarization information are not independent of each other, and the polarization characteristics of the same target also change with the change of wavelength. Channel modulation Fourier transform imaging polarization spectrum technology can simultaneously obtain the intensity, spectral, and polarization information of the target. By combining the advantages of spectral imaging and polarization imaging, the intensity image, spectral information, and full polarization information in the full wavelength range of the target are obtained, which realizes multi-dimensional and all-around characterization of the material composition and surface topography characteristics of the target, and provides support for deeper applications.

[0005] However, due to the limitation of the physical principle of the channel modulation technology itself, such a system is good at detecting smooth broadband polarization spectrum; while in the detection of narrowband polarization spectrum or polarization spectrum with obvious narrowband wave peak and narrowband absorption peak, channel crosstalk will occur between each channel of the interference pattern due to the interference fringe broadening. Affected by the information aliasing between channels, the specific interference channel cannot be accurately extracted for polarization spectrum recovery, which further leads to the problems of waveform distortion and intensity loss of the detected spectral polarization information, and seriously limits the development and application of the channel modulation type interference polarization spectrum technology. Therefore, it is an urgent technical problem to be solved by the present application to reduce the influence of crosstalk on the channel modulation Fourier transform imaging polarization spectrum technology, broaden the applicability of the technology, and promote its better development. SUMMARY

[0006] The technical problem to be solved by the present application is to provide a low-crosstalk channel modulation interference polarization spectrum detection method and system to solve the technical problem of waveform distortion and intensity loss of spectral polarization information caused by channel crosstalk of the current system.

[0007] The purpose of the present application is achieved by the following technical solutions:

[0008] In a first aspect, the present application provides a low-crosstalk channel modulation interference polarization spectrum detection system, which comprises, in sequence according to the direction of light signal propagation, a half-field telescope module, a phase modulation module, an interference modulation module and a detection module.

[0009] The half-field telescope module is used for collimating the input target light beam in the lower half field, and the target light beam propagates in parallel to the phase modulation module according to the set range.

[0010] The phase modulation module comprises a composite polarization beam splitter prism group, which performs light splitting operation based on the target light beam output by the half-field telescope module, and emits two parallel polarized lights.

[0011] The interference modulation module is used for modulating the two polarized lights, and the interference modulation module is used for modulating the two polarized lights respectively, so that the modulated two polarized light beams interfere with each other and are transmitted to the detection module for imaging.

[0012] As a further improvement of the present application, the half-field telescope module comprises a first lens, a half-field diaphragm and a second lens in sequence; the half-field diaphragm is located at the focal point of the first lens and the second lens, and the upper half part has zero transmittance; the target light beam converges at the half-field diaphragm after passing through the first lens, and only the lower half field light beam is emitted after passing through the half-field diaphragm and inputting the second lens, and then collimated and emitted to the phase modulation module.

[0013] As a further improvement of the present application, the phase modulation module further comprises a first phase retarder, a second phase retarder and a half wave plate in sequence; the compound polarization beam splitting prism group is arranged between the second phase retarder and the half wave plate; the half field of view light beam output by the half field of view telescope module is incident to the compound polarization beam splitting prism group after being modulated by the first phase retarder and the second phase retarder; the compound polarization beam splitting prism group is used for splitting the incident light beam into two light beams with orthogonal polarization directions; the two light beams are output to the half wave plate for modulation, and two output light beams with polarization directions of ±45° are obtained.

[0014] As a further improvement of the present application, the phase modulation module output light includes upper light path output light and lower light path output light.

[0015] The Stokes vector of the upper light path output light is:

[0016]

[0017] The Stokes vector of the lower light path output light is:

[0018]

[0019] Wherein S up ( x , y , σ ) and S down ( x , y , σ ) respectively represent the Stokes vectors of the modulated upper light path output light and lower light path output light, S 0~ S 3 are four parameters of the incident light Stokes vector, φ 1, φ 2 respectively represent the phase delay generated by the first phase retarder and the second phase retarder.

[0020] As a further improvement of the present application, the compound polarization beam splitting prism group is formed by cementing a polarization beam splitting cube and a pentagonal prism, and is used for splitting the incident light of the compound polarization beam splitting prism group into two parallel output light beams with orthogonal polarization directions and symmetric about the cementing surface; the s light exit surface of the polarization beam splitting cube is cemented with the light entrance surface of the pentagonal prism; the optical axis of the detection system passes through the cementing plane.

[0021] As a further improvement of the present application, the interference modulation module comprises a beam splitter interferometer and a polarizer and a third lens; the beam splitter interferometer comprises a Wollaston prism set; the Wollaston prism set is used to divide the light emitted by the phase modulation module into two beams of light with orthogonal polarization directions and parallel propagation directions to the polarizer; the polarizer is used to modulate the light emitted by the Wollaston prism set, and two beams of coherent light with the same polarization direction and parallel transmission direction are emitted, which are converged after passing through the third lens and generate interference.

[0022] As a further improvement of the present application, the interference modulation module outputs upper light path interference light and lower light path interference light; the upper light path interference intensity expression is:

[0023]

[0024] The lower light path interference intensity expression is:

[0025]

[0026] In the formula, Δ represents the optical path difference introduced by the interference modulation module, and * represents the complex conjugate, C up and C down represent the interference channels of the upper light path and the lower light path, respectively; the center frequencies of each interference channel are 0, ± φ 2、±( φ 1- φ 2)、±( φ 1+ φ 2) respectively. C * represents the complex conjugate of C .

[0027] As a further improvement of the present application, the light emitted by the interference modulation module is used to interfere on the target surface of the detection module and form an interference image, and the interference image is symmetric about the horizontal center line of the target surface.

[0028] As a further improvement of the present application, after obtaining the interference image, the method further comprises extracting the interference intensity curves of the symmetric rows of pixels in the upper light path and the lower light path interference images and performing superposition operation and / or difference operation, selecting a specific interference channel after superposition and difference processing to demodulate the Stokes parameter, and obtaining the demodulated Stokes parameter.

[0029] In a second aspect, the present application provides a low-crosstalk channel modulation interference polarization spectrum detection method, which is based on the above low-crosstalk channel modulation interference polarization spectrum detection system, and comprises:

[0030] The target light beam passes through the half field of view telescopic module, is collimated, and is emitted in parallel to the composite polarization beam splitter prism group in the phase modulation module according to the set range.

[0031] After the target light beam enters the composite polarization beam splitter prism group, the light splitting operation is also performed, and two parallel polarized lights are emitted.

[0032] The two polarized lights are modulated, the modulated two polarized light beams are interfered, and an interference image is formed.

[0033] The polarization spectrum detection system provided by the application improves the light beam quality processed by the subsequent module through the half field of view telescopic module, reduces the error caused by improper divergence or convergence of the light beam, receives the collimated light beam from the half field of view telescopic module through the composite polarization beam splitter prism group, performs light splitting operation on the light beam, generates two parallel polarized lights, performs independent phase modulation on the two lights through the phase modulation module, provides necessary light beam conditions for subsequent interference modulation, realizes interference effect, receives and modulates the two polarized lights from the phase modulation module through the interference modulation module, makes the two polarized lights interfere, forms an interference pattern, and acquires information about polarization and intensity of the target light beam through interference modulation of the light, which is used for spectrum analysis. The detection module converts the light beam after interference modulation into an electrical signal and forms an image. The application effectively reduces mutual interference between different light paths through the application of the composite polarization beam splitter prism group, improves the purity and measurement accuracy of the signal. In particular, the crosstalk between the 0 channel and other channels can be completely eliminated, the detection accuracy of the narrow-band polarization spectrum or the polarization spectrum with obvious narrow-band wave peak and narrow-band absorption peak is significantly improved, the polarization spectrum detection capability is strong, and the application range is wide. C 0 channel and other channels can be completely eliminated, the detection accuracy of the narrow-band polarization spectrum or the polarization spectrum with obvious narrow-band wave peak and narrow-band absorption peak is significantly improved, the polarization spectrum detection capability is strong, and the application range is wide.

[0034] Further, the data processing method for eliminating crosstalk of the application only involves superposition and difference operation, the process is simple, and the calculation amount is small; the application can realize independent modulation of the upper and lower light paths and symmetrical imaging only by using the composite polarization beam splitter prism group, and has the advantages of simple structure, good stability and easy operation.

[0035] Further, the half field of view telescopic module in the application can effectively limit the light beam range entering the subsequent module by placing the half field diaphragm at the focal point position between the two lenses, ensure that only the light beam of the lower half field of view can continue to propagate, and avoid the complexity and interference possibly caused by the full field of view light beam. The collimated light beam has better directionality and uniformity, and reduces the error caused by improper divergence or convergence of the light beam.

[0036] Further, the light is split into two linearly polarized beams by a polarizing beam splitter cube: one beam is transmitted P-polarized light, and the other is reflected S-polarized light. The P light is almost completely transmitted in the polarizing beam splitter cube, while the S light is mostly reflected, ensuring a high extinction ratio and good imaging quality. A pentagonal prism is used to deflect the incident S light beam by 90 degrees, ensuring that it is parallel to the P light. The S light exit surface of the polarizing beam splitter cube and the pentagonal prism entrance surface are optically cemented together to form a whole. This design not only simplifies the mechanical structure, but also reduces the number of air-glass interfaces, thereby reducing reflection loss and ghost effects. The addition of the pentagonal prism allows the two separated light beams to exit symmetrically from the cemented surface and enter the interference modulation module with the correct polarization state.

[0037] Further, the Wollaston prism group can efficiently split the incident light into two beams with orthogonal polarization directions, and the polarizer can re-adjust the two beams to the same polarization direction. This efficient polarization state separation and recombination process ensures the optimization of the interference conditions, improving the accuracy and reliability of the measurement. By using the Wollaston prism group and the polarizer, the mutual interference between different light paths can be effectively reduced, and the influence of background noise can be reduced. BRIEF DESCRIPTION OF DRAWINGS

[0038] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings described below are some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0039] Figure 1 The structure schematic diagram of the low cross-talk channel modulation interference polarization spectrum detection system in the embodiment of the present application;

[0040] Figure 2 The structure schematic diagram of the phase modulation module based on the composite polarizing beam splitter prism group;

[0041] Figure 3 The optical path schematic diagram of the composite polarizing beam splitter prism group;

[0042] Figure 4 The interference pattern on the target surface of the system detection module generated by simulation;

[0043] Figure 5 is a schematic diagram of the data processing effect of the system for eliminating channel cross-talk, wherein (a) and (c) are the interference intensity curves of the symmetric rows in the upper and lower light path interference patterns, respectively, (b) is the superposition processing result, and (d) is the difference processing result;

[0044] Figure 6 is a schematic diagram of the detection result of the present system on a narrow-band polarization spectrum, wherein (a) isS 0-quantum original and demodulation spectrum, (b) is S 1-quantum original and demodulation spectrum, (c) is S 2-quantum original and demodulation spectrum, (d) is S 3-quantum original and demodulation spectrum.

[0045] Figure 7 is a schematic diagram of the detection results of the system for polarized spectrum with obvious narrow-band wave peak and narrow-band absorption peak, wherein (a) is S 0-quantum original and demodulation spectrum, (b) is S 1-quantum original and demodulation spectrum, (c) is S 2-quantum original and demodulation spectrum, (d) is S 3-quantum original and demodulation spectrum.

[0046] In the figure, 1, half field of view telescope module; 2, phase modulation module; 3, interference modulation module; 4, detection module; 11, first lens; 12, field stop; 13, second lens; 21, first phase retarder; 22, second phase retarder; 23, compound polarization beam splitter prism group; 24, half wave plate; 231, polarization beam splitting cube; 232, pentagonal prism; 31, first Wollaston prism; 32, second Wollaston prism; 33, analyzer; 34, third lens. DETAILED DESCRIPTION

[0047] In order to make the purpose and technical scheme of the present application clearer and more convenient to understand. The following will be combined with the drawings and examples to further describe the present application in detail, the specific examples described here are only for explaining the present application, and are not used to limit the present application.

[0048] The technical scheme of the present application will be described clearly and completely in combination with the drawings and specific examples below, wherein the described examples are only a part of the examples of the present application, not all the examples.

[0049] Example 1:

[0050] As Figure 1 - shown in Figure 7, the present embodiment provides a low crosstalk channel modulation interference polarization spectrum detection system, which comprises half field of view telescope module 1, phase modulation module 2, interference modulation module 3 and detection module 4 in turn according to the direction of light signal propagation.

[0051] As Figure 1As shown, the half-field telescope module 1 is used to collimate the input target beam in the lower half of the field of view, and the target beam propagates parallel to the phase modulation module 2 within a set range. Specifically, the half-field telescope module 1 includes a first lens 11, a half-field stop 12, and a second lens 13 in sequence; the half-field stop 12 is located at the focal point of the first lens 11 and the second lens 13, and the upper half of the light transmittance is zero; after the target beam passes through the first lens 11, it converges at the half-field stop 12, and after being limited by the half-field stop 12, only the lower half of the field of view beam is emitted. After passing through the second lens 13, the beam is collimated and then emitted to the phase modulation module 2.

[0052] like Figure 2 The diagram shows the structure of the phase modulation module 2 based on a composite polarization beam splitter prism group. The phase modulation module 2 sequentially includes a first phase delayer 21, a second phase delayer 22, a composite polarization beam splitter prism group 23, and a half-wave plate 24. The half-field-of-view beam output from the half-field-of-view telescope module 1 is phase-delayed and modulated by the first phase delayer 21 and the second phase delayer 22 before being incident on the composite polarization beam splitter prism group 23. The composite polarization beam splitter prism group 23 splits the incident beam into two beams with orthogonal polarization directions. After being modulated by the half-wave plate 24, the two beams are output as two outgoing beams with polarization directions of ±45°.

[0053] In this embodiment, the fast axis direction angle of the first phase retarder 21 is 0°, and the fast axis direction angle of the second phase retarder 22 is 45°. Furthermore, the thickness of the second phase retarder 22 is twice the thickness of the first phase retarder 21. By setting different fast axis direction angles, effective conversion of the polarization state of the incident light can be achieved. When light passes through the first phase retarder 21, its polarization state is affected by the retarder; subsequently, the light passes through the second phase retarder 22, further altering its polarization state. Specifically, the fast axis direction angle of the first phase retarder 21 being 0° and the fast axis direction angle of the second phase retarder 22 being 45° allows different polarization parameters of the incident beam to be modulated onto carrier waves of different frequencies. The thickness of the second phase retarder 22 being twice the thickness of the first phase retarder 21 ensures that the phase difference between the interference channels is equal.

[0054] The composite polarization beam splitter prism 23 is glued by a polarization beam splitter cube 231 and a pentagonal prism 232, and is used to divide the light incident on the composite polarization beam splitter prism 23 into two beams of parallel outgoing light with orthogonal polarization directions and symmetry about the gluing surface; the S light exit surface of the polarization beam splitter cube 231 is glued with the light entrance surface of the pentagonal prism 232; the optical axis of the detection system in the embodiment passes through the gluing plane. Among them, the lower light path beam is directly emitted, and the polarization direction is vertical; the upper light path beam is incident on the pentagonal prism 232 and is reflected twice, the propagation direction is turned over by 90° and is parallel to the lower light path outgoing light, and the polarization direction is horizontal. At this time, the polarization modulation effects of the polarization beam splitter cube 232 and the pentagonal prism 231 on the light beam can be equivalent to two polarizers with vertical and horizontal polarization directions respectively. The outgoing light of the upper and lower light paths after modulation by the half-wave plate 24 is represented as S up and S down , and the polarization directions are +45° and -45° respectively.

[0055] Figure 2 The modulation principle of the phase modulation module 2 shown in the figure can be represented by Mueller matrix operation. First, the equivalent Mueller matrix of the upper light path is:

[0056] (1)

[0057] wherein, represents the equivalent Mueller matrix of the upper light path, represents the Mueller matrix of the half-wave plate 24, represents the equivalent Mueller matrix of the pentagonal prism 232, represents the Mueller matrix of the second phase retarder 22, represents the Mueller matrix of the first phase retarder 21.

[0058] The equivalent Mueller matrix of the lower light path is:

[0059] (2)

[0060] wherein, represents the equivalent Mueller matrix of the lower light path, represents the equivalent Mueller matrix of the polarization beam splitter cube 231.

[0061] Therefore, the Stokes vectors of the outgoing light of the upper and lower light paths are:

[0062] (3)

[0063] and

[0064] (4)

[0065] wherein, S ( x , y , σ ) represents the Stokes vector of the incident light, S up ( x , y , σ ) and S down ( x , y , σ ) respectively represent the Stokes vector of the upper and lower light paths of the phase-modulated light, S 0~ S 3 are four parameters of the Stokes vector of the incident light, φ 1、 φ 2 respectively represent the phase delay generated by the first phase retarder and the second phase retarder.

[0066] As Figure 3 The optical path of the composite polarization beam splitter prism group 23 is shown. The composite polarization beam splitter prism group 23, which is composed of the polarization beam splitting cube 231 and the pentagonal prism 232, can not only decompose the incident light into two beams with the same intensity and orthogonal polarization directions, but also ensure that the two beams are parallel and symmetric to the bonding surface, thereby ensuring that the system can correctly perform phase modulation and symmetric imaging.

[0067] The interference modulation module 3 is used for modulating two polarization lights respectively, converging the modulated two polarization beams, and forming an interference image in the detection module 4.

[0068] The interference modulation module 3 includes a beam splitter interferometer and a polarizer 33 and a third lens 34; the beam splitter interferometer includes a Wollaston prism group; the Wollaston prism group is used for splitting the light emitted by the phase modulation module 2 into two beams with orthogonal polarization directions and parallel propagation directions and emitting the two beams to the polarizer 33; the polarizer 33 is used for modulating the light emitted by the Wollaston prism group, emitting two beams with the same polarization direction and parallel to each other, and after passing through the third lens 34, the two beams interfere with each other. In the present embodiment, the Wollaston prism group includes a first Wollaston prism 31 and a second Wollaston prism 32.

[0069] Specifically, the two Wollaston prisms are identical. When linearly polarized light is incident on the Wollaston prism array, due to birefringence, the light is decomposed into two waves propagating at different speeds: o-ray (ordinary ray) and e-ray (extraordinary ray). These two beams propagate along different paths and eventually exit with orthogonal polarization directions. The design of the Wollaston prism array ensures that these two beams not only maintain the orthogonality of their polarization states but also that their propagation directions are almost perfectly parallel.

[0070] The analyzer 33 has an analysis angle of 45°. The incident light carries the polarization spectrum information of the target and is split into two beams with orthogonal polarization directions and parallel propagation directions after passing through the Wollaston prism group. The polarizer 33 then makes the polarization directions of the outgoing light the same, and finally the beams are converged by the third lens 34 to form an interference image on the target surface of the detection module 4.

[0071] The principle of interference modulation can be expressed by the following formula:

[0072] (5)

[0073] and

[0074] (6)

[0075] After removing the background terms from expressions (5) and (6), and exponentializing and rearranging the interference terms using Euler's formula, we get:

[0076] (7)

[0077] and

[0078] (8)

[0079] Where Δ represents the optical path difference introduced by the interference modulation module, C up and C down These represent the interference channels of the upper and lower optical paths, respectively. C *represent C The complex conjugate of the vector. After passing through the phase modulation module, the original Stokes vector is weighted and modulated to form seven independent interference channels with center frequencies of 0, ±, and 1. φ 2. ±( φ 1- φ 2) ±( φ 1+ φ 2).

[0080] like Figure 4 The image shown is the interferometric image on the target surface of detector module 4. The detector pixel size simulated in this example is 3036×4024. Combining formulas (7), (8), and Figure 4It can be seen that in the interference pattern formed by the upper and lower light paths, C 0 channels have the same phase and intensity; other channels have the same phase and opposite intensity, that is, the interference maximum in the upper light path interference pattern corresponds to the interference minimum in the lower light path interference pattern.

[0081] As shown in FIG. 5, the data processing effect of eliminating channel crosstalk of the system. FIG. 5 (a) and FIG. 5 (c) are the interference intensity curves of the symmetric rows in the upper and lower light path interference patterns formed by the incident system of the pulse light with the center wavelength of 633 nm and the full width at half maximum of 30 nm. By superimposing the two, the C 0 channel can be completely reserved 0 channel and the intensity of the interference channel is doubled, as shown in FIG. 5 (b), at this time the system is equivalent to a Fourier transform spectrometer. The process can be represented by the following formula:

[0082] (9)

[0083] By difference processing, the C 0 channel can be completely suppressed C 0 channel and the intensity of the interference channel is doubled, as shown in FIG. 5 (d). The process can be represented by the following formula:

[0084] (10)

[0085] After processing, the C 0 channel containing only the spectral information of the incident light and the other channels containing polarization information can be separated, which well eliminates the channel crosstalk and ensures the accuracy of the Stokes parameter detection, especially improves the detection ability of narrow-band polarization spectrum or polarization spectrum with obvious narrow-band wave peak and narrow-band absorption peak. The Stokes parameter recovery process can be represented by the following formula:

[0086] (11)

[0087] As shown in FIG. 6, the detection results of the system for narrow-band polarization spectrum are simulated, and the solid line in each figure represents the spectral line of each Stokes parameter of the incident light, and "*" represents the spectral line of each Stokes parameter detected by the system. FIG. 6 (a) - FIG. 6 (d) represent the Stokes parameters S 0 S 3, it can be seen that the spectral line of the system detection result is smooth and has no jitter, and is well fitted with the original spectral line. Especially after eliminating the C 0 channel crosstalk by superposition and difference processing, the system can detect accurate S 0 parameter information, as shown in FIG. 6 (a). It can be proved that the system has good narrow-band polarization spectrum detection ability.

[0088] As shown in FIG. 7(a)-7(d), to simulate the detection results of the system on the polarized spectrum with obvious narrow-band wave peak and narrow-band absorption peak, it can be seen that the detection result spectrum is smooth without jitter, and is well fitted with the original spectrum without distortion. It can be proved that the system has good detection capability on the polarized spectrum containing obvious narrow-band wave peak and narrow-band absorption peak.

[0089] Embodiment 2

[0090] Based on the low-crosstalk channel modulation interference polarized spectrum detection system described in embodiment 1, the embodiment also provides a low-crosstalk channel modulation interference polarized spectrum detection method. The method mainly comprises:

[0091] After the target light beam passes through the half-field telescope module, the light beam is collimated, and is emitted in parallel to the compound polarization beam splitter prism group in the phase modulation module according to the set range;

[0092] After the target light beam is incident into the compound polarization beam splitter prism group, the light beam is also split, and two parallel polarized light beams are emitted;

[0093] The two polarized light beams are modulated, so that the modulated two polarized light beams interfere to form an interference image.

[0094] The specific principles and corresponding steps of each module have been described in embodiment 1, and will not be repeated here.

Claims

1. A low-crosstalk channel modulation interferometric polarization spectroscopy detection system, characterized in that, Based on the direction of optical signal propagation, the modules consist of a half-field telescope module, a phase modulation module, an interferometric modulation module, and a detection module. The half-field telescope module is used to collimate the input target beam in the lower half-field, and the target beam propagates parallel to the phase modulation module within a set range. The phase modulation module includes a composite polarization beam splitter prism group, which performs beam splitting operation based on the target beam output by the half-field telescope module, and emits two parallel polarized beams. The interference modulation module is used to modulate the two polarized beams separately, so that the two modulated polarized beams interfere and are transmitted to the detection module for imaging. The half-field telescope module includes a first lens, a half-field aperture, and a second lens in sequence. The half-field aperture is located at the focal point of the first lens and the second lens, and the upper half of the aperture has zero transmittance. The target beam converges at the half-field aperture after passing through the first lens. After passing through the half-field aperture, only the lower half-field beam is emitted and input into the second lens. After beam collimation, the beam is emitted to the phase modulation module. The composite polarization beam splitter prism assembly is composed of a polarization beam splitter cube and a pentagonal prism cemented together. It is used to split the light incident on the composite polarization beam splitter prism assembly into two parallel outgoing beams with orthogonal polarization directions and symmetrical about the cemented surface. The s-beam exit surface of the polarization beam splitter cube is cemented with the incident surface of the pentagonal prism. The optical axis of the detection system passes through the cemented plane.

2. The low crosstalk channel modulation interferometric polarization spectroscopy detection system according to claim 1, characterized in that, The phase modulation module also includes a first phase delayer, a second phase delayer, and a half-wave plate in sequence; a composite polarization beam splitter group is disposed between the second phase delayer and the half-wave plate; the half-field beam output by the half-field telescope module is modulated by the first phase delayer and the second phase delayer and then incident on the composite polarization beam splitter group; the composite polarization beam splitter group is used to split the incident beam into two beams with orthogonal polarization directions; after the two beams are modulated by the half-wave plate, two outgoing beams with polarization directions of ±45° are obtained.

3. The low crosstalk channel modulation interferometric polarization spectroscopy detection system according to claim 2, characterized in that, The phase modulation module emits light from the upper optical path and the lower optical path. The Stokes vector of the light emitted from the upper optical path is: The Stokes vector of the light emitted from the lower optical path is: in S up ( x , y , σ )and S down ( x , y , σ ) represent the Stokes vectors of the modulated upper and lower optical paths, respectively. S 0~ S 3 represents the four parameters of the incident light Stokes vector. φ 1. φ 2 represents the phase delay generated by the first phase delayer and the second phase delayer, respectively.

4. The low crosstalk channel modulation interferometric polarization spectroscopy detection system according to claim 1, characterized in that, The interference modulation module includes a beam splitter, an analyzer, and a third lens; the beam splitter includes a Wollaston prism group; the Wollaston prism group is used to split the light emitted from the phase modulation module into two beams with orthogonal polarization directions and parallel propagation directions, which are then directed to the analyzer; the analyzer is used to modulate the light emitted from the Wollaston prism group, resulting in two parallel beams with the same polarization direction, which converge and interfere after passing through the third lens.

5. The low crosstalk channel modulation interferometric polarization spectroscopy detection system according to claim 1, characterized in that, The interference modulation module outputs upper and lower optical path interference light; the expression for the upper optical path interference intensity is: The expression for the lower optical path interference intensity is: In the formula, Δ represents the optical path difference introduced by the interference modulation module, and * denotes complex conjugate. C up and C down These represent the interference channels of the upper and lower optical paths, respectively; the center frequencies of each interference channel are 0 and ±, respectively. φ 2. ±( φ 1- φ 2) ±( φ 1+ φ 2); C *represent C .

6. The low crosstalk channel modulation interferometric polarization spectroscopy detection system according to claim 4, characterized in that, The light emitted from the interference modulation module is used to interfere with the target surface of the detection module and form an interference image, which is symmetrical about the horizontal center line of the target surface.

7. The low crosstalk channel modulation interferometric polarization spectroscopy detection system according to claim 6, characterized in that, After acquiring the interference image, the process also includes extracting the interference intensity curves of symmetrical row pixels in the upper and lower optical path interference images and performing superposition and / or differential operations. Then, specific interference channels after superposition and differential processing are selected for Stokes parameter demodulation to obtain the demodulated Stokes parameters.

8. A low-crosstalk channel modulation interferometric polarization spectroscopy detection method, based on the low-crosstalk channel modulation interferometric polarization spectroscopy detection system according to any one of claims 1-7, characterized in that, include: After the target beam passes through the half-field telescope module, the lower half-field beam is collimated and then emitted parallel to the composite polarization beam splitter group in the phase modulation module within a set range. After the target beam enters the composite polarization beam splitter prism group, it is further split into two parallel polarized beams. Two polarized beams are modulated to cause them to interfere, forming an interference image.

Images