Low-crosstalk channel modulation interference polarization spectrum detection method and system

Abstract

The invention relates to the technical field of optics, in particular to a low-crosstalk channel modulation interference polarization spectrum detection method and system, and the system comprises a half-field telescopic module, a phase modulation module, an interference modulation module and a detection module. The half-view-field telescope module is used for performing lower half-view-field beam collimation on an input target beam, the target beam is propagated to the phase modulation module in parallel according to a set range, a composite polarization splitting prism group in the phase modulation module performs light splitting operation based on the target beam output by the half-view-field telescope module, and two parallel polarized lights are emitted, independent phase modulation of the two paths of light is ensured; and the interference modulation module is used for performing light splitting modulation according to the two paths of polarized light to ensure that the two paths of modulated polarized light beams interfere with each other and are transmitted to the detection module for imaging. According to the system, the detection precision of a narrow-band polarization spectrum or a polarization spectrum with an obvious narrow-band wave crest and a narrow-band absorption peak is improved, the polarization spectrum detection capability is high, and the application range is wide.

Description

Technical Field

[0001] The invention relates to the field of optical technology, and in particular to a low-crosstalk channel modulation interference polarization spectrum detection method and system. Background Art

[0002] After light interacts with matter, its physical properties will change, and optical information such as light intensity, spectrum and polarization will also change accordingly. By detecting these optical information, important characteristics such as the material composition and surface structure of the target object can be obtained. With the deepening of scientific research and engineering applications, traditional photoelectric detection methods represented by intensity imaging can no longer meet the increasingly complex detection needs. Photoelectric detection technology is developing towards the fusion acquisition of multi-dimensional optical information, thereby achieving more accurate and comprehensive target identification. The continuous advancement of optoelectronic technology has significantly improved the performance of various optical components. With these advances, multi-dimensional optical imaging technologies (such as spectral imaging and polarization imaging) have also developed rapidly and have 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 targets have their own unique characteristics. Analyzing these spectra can achieve the classification and identification of targets. Polarization imaging technology can simultaneously obtain the two-dimensional spatial intensity information and one-dimensional polarization information of the target. It is highly sensitive to the roughness, surface structure, contour characteristics, humidity, etc. of the target, and the polarization characteristics of different materials vary significantly. It can effectively enhance the contour of the target and achieve the classification and identification of materials.

[0004] Spectral information and polarization information are not independent of each other, and the polarization characteristics of the same target will also change with the change of wavelength. Channel Modulated Fourier Transform Imaging Polarization Spectroscopy can simultaneously obtain the intensity, spectrum and polarization information of the target, combining the advantages of spectral imaging and polarization imaging, and by obtaining the intensity image, spectral information and full polarization information of the target in the full band, it can achieve multi-dimensional and all-round characterization of the material composition and surface morphology of the target, providing support for deeper applications.

[0005] However, limited by the physical principles of the channel modulation technology itself, this type of system works better when detecting smooth broadband polarization spectra; when detecting narrowband polarization spectra or polarization spectra with obvious narrowband peaks and narrowband absorption peaks, due to the broadening of interference fringes, channel crosstalk will occur between the channels of the interference pattern. Affected by the aliasing of information between channels, it is impossible to accurately extract a specific interference channel for polarization spectrum restoration, which leads to waveform distortion, intensity loss and other problems in the detected spectral polarization information, which seriously limits the development and application of channel modulation interference polarization spectroscopy technology. Therefore, reducing the impact of crosstalk on channel modulation Fourier transform imaging polarization spectroscopy technology, broadening the applicability of this technology, and promoting its better development are technical problems that need to be solved in the present invention. Summary of the invention

[0006] The technical problem to be solved by the present invention is to provide a low-crosstalk channel modulation interference polarization spectroscopy detection method and system in view of the deficiencies in the above-mentioned prior art, which is used to solve the technical problem of waveform distortion and intensity loss of spectral polarization information caused by channel crosstalk in the current system.

[0007] The objective of the present invention is achieved by the following technical solutions: In a first aspect, the present invention provides a low crosstalk channel modulation interferometric polarization spectrum detection system, which includes a half-field telescope module, a phase modulation module, an interferometric modulation module, and a detection module in sequence according to the direction of light signal propagation; The half-field telescope module is used to collimate the input target beam into the lower half-field beam, and the target beam is propagated in parallel to the phase modulation module according to the set range; The phase modulation module includes a composite polarization beam splitter prism group, which performs a beam splitting operation based on the target light beam output by the half-field telescope module, and emits two parallel polarized lights; The interference modulation module is used to modulate the two polarized lights respectively, so that the two modulated polarized light beams interfere with each other and are transmitted to the detection module for imaging.

[0008] As a further improvement of the present invention, the half-field telescope module includes 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 transmittance of the upper half is zero; the target light beam converges at the half-field diaphragm after passing through the first lens, and only the light beam in the lower half of the field is emitted after passing through the half-field diaphragm and input into the second lens, and then the light beam is collimated and emitted to the phase modulation module.

[0009] As a further improvement of the present invention, the phase modulation module also includes a first phase retarder, a second phase retarder and a half-wave plate in sequence; a composite polarization beam splitter prism group is arranged between the second phase retarder and the half-wave plate; the half-field light beam output by the half-field telescope module is modulated by the first phase retarder and the second phase retarder, and then incident on the composite polarization beam splitter prism group; the composite polarization beam splitter prism group is used to split the incident light beam into two light beams with orthogonal polarization directions; after the two light beams are emitted to the half-wave plate for modulation, two output lights with polarization directions of ±45° are obtained.

[0010] As a further improvement of the present invention, the phase modulation module output light includes the upper light path output light and the lower light path output light; The Stokes vector of the light emitted from the upper optical path is:

[0011] The Stokes vector of the light emitted from the lower optical path is:

[0012] in S up ( x , y , s )and S down ( x , y , s ) represent the Stokes vectors of the upper and lower optical paths after modulation, S 0~ S 3 are the four parameters of the incident light Stokes vector, f 1. f 2 represent the phase delay produced by the first phase delayer and the second phase delayer respectively.

[0013] As a further improvement of the present invention, the composite polarization beam splitter prism group is formed by gluing a polarization beam splitter cube and a pentagonal prism, and is used to split the light incident on the composite polarization beam splitter prism group into two parallel outgoing lights with orthogonal polarization directions and symmetrical about the gluing plane; the s-light outgoing surface of the polarization beam splitter cube is glued to the light incident surface of the pentagonal prism; and the optical axis of the detection system passes through the gluing plane.

[0014] As a further improvement of the present invention, the interference modulation module includes a beam splitter interferometer, an analyzer and a third lens; the beam splitter interferometer includes a Wollaston prism group; the Wollaston prism group is used to split the output light of the phase modulation module into two beams of light with orthogonal polarization directions and parallel propagation directions and emit them to the analyzer; the analyzer is used to modulate the light output from the Wollaston prism group, and the two coherent light beams with the same output polarization direction and parallel transmission directions converge and generate interference after passing through the third lens.

[0015] As a further improvement of the present invention, the interference modulation module outputs upper light path interference light and lower light path interference light; the upper light path interference intensity expression is:

[0016] The expression of the interference intensity of the lower optical path is:

[0017] Where Δ represents the optical path difference introduced by the interferometric modulation module, * represents the complex conjugate, C up and C down They represent the interference channel of the upper optical path and the interference channel of the lower optical path respectively; the center frequencies of the interference channels are 0, ± f 2. ±( f 1- f 2) ±( f 1+ f 2); C *represent C The complex conjugate of .

[0018] As a further improvement of the present invention, the output light of 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 vertically symmetrical with respect to the horizontal center line of the target surface as the axis.

[0019] As a further improvement of the present invention, after obtaining the interference image, it also includes extracting the interference intensity curves of the symmetrical row pixels in the interference images of the upper light path and the lower light path and performing superposition operations and / or differential operations, selecting a specific interference channel after superposition and differential processing to perform Stokes parameter demodulation, and obtaining the demodulated Stokes parameters.

[0020] In a second aspect, the present invention provides a low-crosstalk channel modulation interferometry polarization spectrum detection method, based on the above-mentioned low-crosstalk channel modulation interferometry polarization spectrum detection system, comprising: After the target beam passes through the half-field telescope module, the lower half-field beam is collimated and emitted in parallel to the composite polarization beam splitter group in the phase modulation module according to the set range; After the target light beam enters the composite polarization beam splitter prism group, it also performs a beam splitting operation to emit two parallel polarized lights; The two polarized lights are modulated so that the two modulated polarized light beams interfere with each other to form an interference image.

[0021] The beneficial effects of the present invention are as follows: the polarization spectrum detection system provided by the present invention improves the quality of the light beam processed by the subsequent modules through the half-field telescope module, and reduces the errors caused by improper light beam divergence or convergence; receives the collimated light beam from the half-field telescope module through the composite polarization beam splitting prism group, and performs beam splitting operation on it to generate two parallel polarized lights; independently phase modulates the two lights through the phase modulation module to provide the necessary light beam conditions for the subsequent interference modulation to achieve the interference effect; receives and modulates the two polarized lights from the phase modulation module through the interference modulation module, so that they interfere and form an interference pattern. The module can obtain information about the polarization, intensity, etc. of the target light beam for spectral analysis by interferometric modulation of light. The detection module receives the light beam after interference modulation, converts it into an electrical signal, and performs imaging. The present invention effectively reduces the mutual interference between different light paths and improves the purity of the signal and the measurement accuracy through the use of the composite polarization beam splitting prism group. In particular, it can completely eliminate C The crosstalk between channel 0 and other channels significantly improves the detection accuracy of narrow-band polarization spectra or polarization spectra with obvious narrow-band peaks and narrow-band absorption peaks. The polarization spectrum has strong detection capability and a wide range of applications.

[0022] Furthermore, the data processing method for eliminating crosstalk in the present invention only involves superposition and differential operations, and the process is simple and the amount of calculation is small. The present invention can achieve independent modulation of the upper and lower light paths and symmetrical imaging by only using a composite polarization beam splitting prism group, and has a simple structure, good stability, and easy operation.

[0023] Furthermore, the half-field telescope module of the present invention can effectively limit the range of the beam entering the subsequent module by placing the half-field aperture at the focal position between the two lenses, ensuring that only the beam in the lower half of the field of view can continue to propagate, avoiding the complexity and interference that may be caused by the full-field beam. The collimated beam has better directionality and uniformity, reducing the error caused by improper beam divergence or convergence.

[0024] Furthermore, the light is split into two beams of linearly polarized light by a polarization beam splitter cube: one is a transmitted P-polarized light, and the other is a reflected S-polarized light. The P-light is almost completely transmitted in the polarization beam splitter cube, while the S-light is mostly reflected, ensuring a high extinction ratio and good imaging quality. The pentagonal prism can deflect the incident S-light beam by 90 degrees and then emit it to ensure that it is parallel to the P-light. The S-light exit surface of the polarization beam splitter cube and the light entrance surface of the pentagonal prism are optically bonded 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 losses and ghost effects. The addition of the pentagonal prism allows the two separated light beams to be emitted symmetrically on the bonding surface and incident on the interferometric modulation module with the correct polarization state.

[0025] Furthermore, the Wollaston prism group can efficiently split the incident light into two beams with orthogonal polarization directions, while the analyzer can readjust the two beams to the same polarization direction. This efficient polarization state separation and recombination process ensures the optimization of interference conditions and improves the accuracy and reliability of measurement. By using the Wollaston prism group and the analyzer, the mutual interference between different optical paths can be effectively reduced, and the impact of background noise can be reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0027] Figure 1 It is a schematic structural diagram of a low crosstalk channel modulation interferometry polarization spectroscopy detection system in an embodiment of the present invention; Figure 2 It is a schematic diagram of the phase modulation module structure based on the composite polarization beam splitting prism group; Figure 3 Schematic diagram of the optical path of the composite polarization beam splitter prism group; Figure 4 The interference pattern on the target surface of the system detection module generated by simulation; FIG5 is a schematic diagram of the data processing effect of the system eliminating channel crosstalk, wherein (a) and (c) are the interference intensity curves of the symmetrical rows in the upper and lower optical path interference diagrams, respectively, (b) is the superposition processing result, and (d) is the difference processing result; Figure 6 is a schematic diagram of the detection results of the narrow-band polarization spectrum simulated by this system, where (a) is S The original and demodulated spectra of 0 parameters, (b) are S 1 parameter original and demodulated spectra, (c) is S The original and demodulated spectra of 2 parameters, (d) are S 3. Original and demodulated spectra of parameters; FIG7 is a schematic diagram of the detection results of the polarization spectrum with obvious narrow-band peaks and narrow-band absorption peaks simulated by this system, where (a) is S The original and demodulated spectra of 0 parameters, (b) are S 1 parameter original and demodulated spectra, (c) is S The original and demodulated spectra of 2 parameters, (d) are S Original and demodulated spectra of 3 parameters.

[0028] In the figure, 1. half-field telescope module; 2. phase modulation module; 3. interference modulation module; 4. detection module; 11. first lens; 12. field aperture; 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 splitter cube; 232. pentagonal prism; 31. first Wollaston prism; 32. second Wollaston prism; 33. analyzer; 34. third lens. DETAILED DESCRIPTION

[0029] In order to make the purpose and technical solution of the present invention clearer and easier to understand, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. The specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0030] The technical solution of the present invention will be clearly and completely described below in conjunction with the accompanying drawings and specific embodiments, wherein the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments.

[0031] Embodiment 1: like Figure 1 -As shown in FIG7 , this embodiment provides a low-crosstalk channel modulation interference polarization spectroscopy detection system, which includes a half-field telescope module 1, a phase modulation module 2, an interference modulation module 3 and a detection module 4 in sequence according to the direction of light signal propagation.

[0032] like Figure 1 As shown, the half-field telescope module 1 is used to collimate the input target light beam into the lower half field beam, and the target light beam is propagated in parallel to the phase modulation module 2 according to the set range. Specifically, the half-field telescope module 1 includes a first lens 11, a half-field aperture 12 and a second lens 13 in sequence; the half-field aperture 12 is located at the focus of the first lens 11 and the second lens 13, and the transmittance of the upper half is zero; the target light beam converges at the half-field aperture 12 after passing through the first lens 11, and after being restricted by the half-field aperture 12, only the lower half field beam is emitted, passing through the second lens 13, and then emitted to the phase modulation module 2 after the beam is collimated.

[0033] like Figure 2The structure of the phase modulation module 2 based on the composite polarization beam splitter prism group is shown. The phase modulation module 2 includes a first phase retarder 21, a second phase retarder 22, a composite polarization beam splitter prism group 23 and a half-wave plate 24 in sequence. The half-field light beam output by the half-field telescope module 1 is phase-delayed and modulated by the first phase retarder 21 and the second phase retarder 22, and then incident on the composite polarization beam splitter prism group 23; the composite polarization beam splitter prism group 23 is used to split the incident light beam into two light beams with orthogonal polarization directions; after the two light beams are emitted to the half-wave plate 24 for modulation, two outgoing lights with polarization directions of ±45° are obtained.

[0034] Among them, the fast axis direction angle of the first phase retarder 21 is 0°, the fast axis direction angle of the second phase retarder 22 is 45°, and in this embodiment, 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 the light passes through the first phase retarder 21, its polarization state will be affected by the retarder; then, the light passes through the second phase retarder 22, further changing its polarization state. Specifically, 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°, which can modulate different partial parameters of the incident light beam into carriers of different frequencies. The thickness of the second phase retarder 22 is twice the thickness of the first phase retarder 21, which can ensure that the phase difference between the interference channels is equal.

[0035] The composite polarization beam splitter prism group 23 is formed by gluing a polarization beam splitter cube 231 and a pentagonal prism 232, and is used to split the light incident on the composite polarization beam splitter prism group 23 into two parallel outgoing light beams with orthogonal polarization directions and symmetrical about the gluing plane; the S light outgoing surface of the polarization beam splitter cube 231 is glued to the light incident surface of the pentagonal prism 232; the optical axis of the detection system in this embodiment passes through the gluing plane. Among them, the lower light path light beam is directly emitted, and the polarization direction is vertical; the upper light path light beam is incident on the pentagonal prism 232 and reflected twice, and the propagation direction is flipped 90° and is emitted parallel to the lower light path outgoing light, and the polarization direction is horizontal. At this time, the polarization modulation effect 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 being modulated by the half-wave plate 24 is respectively expressed as S up and S down , the polarization directions are +45° and -45° respectively.

[0036] Figure 2 The modulation principle of the phase modulation module 2 shown can be expressed by Mueller matrix operation. First, the equivalent Mueller matrix of the optical path is: (1) in, represents the equivalent Mueller matrix of the upper optical path, represents the Mueller matrix of the half-wave plate 24, represents the equivalent Mueller matrix of the pentaprism 232, represents the Mueller matrix of the second phase retarder 22, represents the Mueller matrix of the first phase retarder 21.

[0037] The equivalent Mueller matrix of the optical path is: (2) in, represents the equivalent Mueller matrix of the lower optical path, represents the equivalent Mueller matrix of the polarization beam splitting cube 231.

[0038] Therefore, the Stokes vector of the light emitted from the upper and lower optical paths is: (3) and (4) in, S ( x , y , s ) represents the Stokes vector of the incident light, S up ( x , y , s )and S down ( x , y , s ) represent the Stokes vectors of the light emitted from the upper and lower optical paths after phase modulation, S 0~ S 3 are the four parameters of the incident light Stokes vector, f 1. f 2 represent the phase delay produced by the first phase delayer and the second phase delayer respectively.

[0039] like Figure 3 The figure shows the optical path of the composite polarization beam splitter prism set 23. The composite polarization beam splitter prism set 23, which is formed by gluing the polarization beam splitter cube 231 and the pentagonal prism 232, can not only decompose the incident light into two beams of light with the same intensity and orthogonal polarization directions, but also ensure that the two beams of light have parallel exit directions and are symmetrical with the gluing surface, thereby ensuring that the system can correctly perform phase modulation and symmetrical imaging.

[0040] The interference modulation module 3 is used to modulate the two polarized lights respectively, converge the two modulated polarized light beams, and form an interference image in the detection module 4.

[0041] The interferometric modulation module 3 includes a beam splitter interferometer and an analyzer 33 and a third lens 34; the beam splitter interferometer includes a Wollaston prism group; the Wollaston prism group is used to split the output light of the phase modulation module 2 into two beams of light with orthogonal polarization directions and parallel propagation directions and emit them to the analyzer 33; the analyzer 33 is used to modulate the light output from the Wollaston prism group, and output two parallel beams of light with the same polarization direction, which interfere after passing through the third lens 34. The Wollaston prism group in this embodiment includes a first Wollaston prism 31 and a second Wollaston prism 32.

[0042] Specifically, the two Wollaston prisms are exactly the same. When linearly polarized light is incident on the Wollaston prism group, due to the birefringence effect, the light will be decomposed into two waves propagating at different speeds: o light (ordinary light) and e light (extraordinary light). The two beams of light propagate along different paths and eventually emerge in the form of orthogonal polarization directions. The design of the Wollaston prism group ensures that the two beams of light not only maintain the orthogonality of the polarization state, but also their propagation directions are almost completely parallel.

[0043] The polarization angle of the polarizer 33 is 45°. The incident light carries the polarization spectrum information of the target, passes through the Wollaston prism group and is divided into two beams with orthogonal polarization directions and parallel propagation directions, and then passes through the polarizer 33 to make the polarization directions of the outgoing light the same, and finally converges through the third lens 34 to form an interference image on the target surface of the detection module 4.

[0044] The interferometric modulation principle can be expressed by the following formula: (5) and (6) Removing the background terms in expressions (5) and (6), and indexing and arranging the interference terms using the Euler formula, we can obtain: (7) and (8) Where Δ represents the optical path difference introduced by the interferometric modulation module, C up and C down Represent the interference channels of the upper and lower optical paths respectively, C *represent C After passing through the phase modulation module, the original Stokes vector is weighted modulated to form seven independent interference channels, with center frequencies of 0, ± f 2. ±( f 1- f 2) ±( f 1+ f 2).

[0045] like Figure 4 The interference image on the target surface of the detection module 4 is shown. The detector pixel simulated in this example is 3036×4024. Combining formula (7), formula (8) and Figure 4 It can be seen that in the interference pattern formed by the upper and lower light paths, C The phase and intensity of channel 0 are the same; the phases of other channels are the same but the intensities are opposite, that is, the interference maximum in the interference diagram of the upper optical path corresponds to the interference minimum in the interference diagram of the lower optical path.

[0046] As shown in Figure 5, the data processing effect of eliminating channel crosstalk in this system is shown. Figure 5 (a) and Figure 5 (c) are the interference intensity curves of the symmetrical lines in the upper and lower optical path interference diagrams formed by simulating a pulse light incident system with a central wavelength of 633nm and a half-maximum full width of 30nm. By superimposing the two, the C 0 channel and double the intensity of the interference channel, as shown in Figure 5 (b). At this time, the system is equivalent to a Fourier transform spectrometer. The process can be expressed by the following formula: (9) By performing differential processing on the two, the C 0 channel, thereby eliminating C 0 channel crosstalks other interference channels and doubles the intensity of the interference channel, as shown in Figure 5 (d). This process can be expressed by the following formula: (10) After processing, only the incident light spectrum information can be C The 0 channel is separated from other channels containing polarization information, which effectively eliminates channel crosstalk and ensures the accuracy of Stokes parameter detection, especially improving the detection capability of narrow-band polarization spectra or polarization spectra with obvious narrow-band peaks and narrow-band absorption peaks. The Stokes parameter recovery process can be expressed by the following formula: (11) As shown in Figure 6, in order to simulate the detection results of the system for narrow-band polarization spectrum, the solid line in each figure represents the spectrum of each Stokes parameter of the incident light, and the "*" represents the spectrum of each Stokes parameter detected by the system. Figure 6 (a)-Figure 6 (d) represent the Stokes parameters respectively. S 0~ S 3. It can be seen that the spectrum of the detection result of this system is smooth and has no jitter, and fits well with the original spectrum, especially after the superposition difference processing eliminatesC After 0 channel crosstalk, the system can detect and obtain accurate S 0 parameter information, as shown in Figure 6 (a). This proves that the system has good narrow-band polarization spectrum detection capability.

[0047] As shown in Figure 7 (a) to Figure 7 (d), the detection results of the polarization spectrum with obvious narrow-band peaks and narrow-band absorption peaks by the system are simulated. It can be seen that the detection result spectrum is smooth without jitter, and fits well with the original spectrum without distortion. It can be proved that the system has good detection capability for polarization spectra with obvious narrow-band peaks and narrow-band absorption peaks.

[0048] Example 2 Based on the low crosstalk channel modulation interferometry polarization spectrum detection system described in Example 1, this embodiment also provides a low crosstalk channel modulation interferometry polarization spectrum detection method. The method mainly includes: After the target beam passes through the half-field telescope module, the lower half-field beam is collimated and emitted in parallel to the composite polarization beam splitter group in the phase modulation module according to the set range; After the target light beam enters the composite polarization beam splitter prism group, it also performs a beam splitting operation to emit two parallel polarized lights; The two polarized lights are modulated so that the two modulated polarized light beams interfere with each other to form an interference image.

[0049] The specific principles and corresponding steps of each module have been described in Example 1 and will not be repeated here.

Claims

1. A low crosstalk channel modulation interferometry polarization spectroscopy detection system, characterized in that: According to the propagation direction of the optical signal, it includes a half-field telescope module, a phase modulation module, an interference modulation module and a detection module in sequence; The half-field telescope module is used to collimate the input target beam into the lower half-field beam, and the target beam is propagated in parallel to the phase modulation module according to the set range; The phase modulation module includes a composite polarization beam splitter prism group, which performs a beam splitting operation based on the target light beam output by the half-field telescope module, and emits two parallel polarized lights; The interference modulation module is used to modulate the two polarized lights respectively, so that the two modulated polarized light beams interfere with each other and are transmitted to the detection module for imaging.

2. The low crosstalk channel modulation interferometry polarization spectroscopy detection system according to claim 1, characterized in that: The half-field telescope module includes 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 transmittance of the upper half is zero; 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 input into the second lens, and then the light beam is collimated and emitted to the phase modulation module.

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

4. The low crosstalk channel modulation interferometry polarization spectroscopy detection system according to claim 3, characterized in that: The output light of the phase modulation module includes the output light of the upper optical path and the output light of 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 upper and lower optical paths after modulation, S 0~ S 3 are the four parameters of the incident light Stokes vector, φ 1. φ 2 represent the phase delay produced by the first phase delayer and the second phase delayer respectively.

5. The low crosstalk channel modulation interferometry polarization spectroscopy detection system according to claim 3, characterized in that: The composite polarization beam splitter prism group is formed by gluing a polarization beam splitter cube and a pentagonal prism, and is used to split the light incident on the composite polarization beam splitter prism group into two parallel outgoing lights with orthogonal polarization directions and symmetrical about the gluing plane; the s-light outgoing surface of the polarization beam splitter cube is glued to the light incident surface of the pentagonal prism; the optical axis of the detection system passes through the gluing plane.

6. The low crosstalk channel modulation interferometry polarization spectroscopy detection system according to claim 1, characterized in that: The interference modulation module includes a beam splitter interferometer, an analyzer and a third lens; the beam splitter interferometer includes a Wollaston prism group; the Wollaston prism group is used to split the output light of the phase modulation module into two beams of light with orthogonal polarization directions and parallel propagation directions and emit them to the analyzer; the analyzer is used to modulate the light output from the Wollaston prism group, and output two parallel beams of light with the same polarization direction, which converge and interfere after passing through the third lens.

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

8. The low crosstalk channel modulation interferometry polarization spectroscopy detection system according to claim 6, characterized in that: The emitted light of 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 vertically symmetrical with respect to the horizontal center line of the target surface as an axis.

9. The low crosstalk channel modulation interferometry polarization spectroscopy detection system according to claim 8, characterized in that: After obtaining the interference image, the method also includes extracting the interference intensity curves of the symmetrical row pixels in the interference images of the upper light path and the lower light path and performing superposition operation and / or differential operation, selecting a specific interference channel after superposition and differential processing to perform Stokes parameter demodulation, and obtaining the demodulated Stokes parameters.

10. A low-crosstalk channel modulation interferometry polarization spectroscopy detection method, based on the low-crosstalk channel modulation interferometry polarization spectroscopy detection system according to any one of claims 1 to 9, characterized in that: include: After the target beam passes through the half-field telescope module, the lower half-field beam is collimated and emitted in parallel to the composite polarization beam splitter group in the phase modulation module according to the set range; After the target light beam enters the composite polarization beam splitter prism group, it also performs a beam splitting operation to emit two parallel polarized lights; The two polarized lights are modulated so that the two modulated polarized light beams interfere with each other to form an interference image.

Images