Liquid crystal spatial light modulation spectrometer and measurement method thereof

Abstract

The present invention provides a liquid crystal spatial light modulation spectrometer and a measurement method thereof, wherein the spectrometer includes: a light source system, a liquid crystal phase control array, a liquid crystal optical switch array, and a detector system; the light source system is used to emit a linearly polarized light beam incident on the liquid crystal phase control array, and the linearly polarized light beam is transmitted through the liquid crystal phase control array to obtain a light field array with a preset optical path difference; the liquid crystal optical switch array is used to select the light field array, so that the light beams corresponding to at least two different light field units in the light field array are incident on the detector system to interfere to form an interference light beam, obtain an interference pattern sequence, and obtain the spectral information of the linearly polarized light beam. The present invention avoids the moving mirror scanning mechanism and beam splitting system of the traditional Fourier transform spectrometer, reduces the volume and weight of the system, and improves energy utilization. The micro-spectrometer structure proposed by the invention has the characteristics of miniaturization, lightweight, and high energy utilization.

Description

Technical Field

[0001] The present invention relates to the field of spectral technology, and in particular to a liquid crystal spatial light modulation spectrometer and a measurement method thereof. Background Art

[0002] Spectroscopic technology can obtain information about the composition and content of target substances. It has been increasingly applied in fields such as physical experiments, chemical analysis, biological characterization, medical testing, and ecological and environmental protection, and has played a vital role in the exploration and discovery of new materials, new energy sources, and the unknown world. To obtain the spectral characteristics of the target, the detected complex light must be spectrally decomposed. Currently, commonly used spectroscopic instruments mainly use filter spectroscopy, prism spectroscopy, grating spectroscopy, and interference spectroscopy. Among them, Fourier transform spectroscopy, which uses interference spectroscopy, has become a high-end instrument in many application fields due to its advantages such as multi-channel, high throughput, accurate wavenumber, and low stray light.

[0003] In recent years, with the emergence and development of emerging scientific and technological fields such as space exploration, aerial remote sensing, Earth surveying, atmospheric monitoring, and military reconnaissance, the specialized applications and environments of these instruments have created an urgent need for miniaturized, static Fourier transform spectrometers. This escalating demand has led to insurmountable technical bottlenecks in conventional Fourier transform spectrometers. Currently, the Fourier transform spectrometers commonly used in laboratories employ a time-modulated interferometer structure, where a moving mirror scans the interferometer to generate an optical path difference to obtain spectral information. These instruments incorporate a high-precision moving mirror scanning mechanism for precise sampling of the interferogram. This mechanism is complex to manufacture, sensitive to vibration, and demanding in its operating environment. Furthermore, the moving mirror scanning mechanism is large and heavy. Furthermore, the use of a beam splitter for light separation results in half the energy loss, reducing system stability and reliability, making it unsuitable for aerospace applications such as meteorological observation and atmospheric remote sensing. This, in turn, limits its application in high-tech fields such as space exploration, meteorological remote sensing, and military reconnaissance. Summary of the Invention

[0004] In light of the above issues, the present invention proposes a liquid crystal spatial light modulation spectrometer and its measurement method. By utilizing a liquid crystal phase control array and a liquid crystal optical switch array, spatially distributed phase modulation of the lateral light field and gated interferometry of the light field units are performed to obtain an interferogram signal representing each sampled optical path difference. This eliminates the moving mirror scanning mechanism and beam splitting system of a conventional Fourier transform spectrometer, reduces the system's size and weight, and improves energy efficiency. The proposed miniature spectrometer structure is characterized by its compactness, lightweight design, and high energy efficiency.

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

[0006] The present invention provides a liquid crystal spatial light modulation spectrometer, comprising: a light source system, a liquid crystal phase control array, a liquid crystal optical switch array and a detector system;

[0007] The light source system is used to emit a linearly polarized light beam that is incident on a liquid crystal phase control array. After the linearly polarized light beam passes through the liquid crystal phase control array, a light field array with a preset optical path difference is obtained. The liquid crystal optical switch array is used to select the light field array so that the light beams corresponding to at least two different light field units in the light field array are incident on the detector system to interfere and form an interference beam, thereby obtaining an interference pattern sequence and acquiring the spectral information of the linearly polarized light beam.

[0008] Preferably, the light source system comprises: a light source, a collimator and a polarizer;

[0009] The light source is used to emit a divergent light beam, which is collimated by a collimator to form a parallel light beam and incident on a polarizer; the polarizer converts the parallel light beam into linearly polarized light and incident on a liquid crystal phase control array.

[0010] Preferably, the liquid crystal phase control array includes, from top to bottom, an upper transparent substrate, an upper transparent electrode, an upper alignment film, a liquid crystal layer, a lower alignment film, a transparent electrode array and a lower transparent substrate.

[0011] The upper transparent substrate and the lower transparent substrate together form a liquid crystal cell to fix the liquid crystal layer;

[0012] The upper and lower surfaces of the upper transparent substrate and the lower transparent substrate are coated with antireflection films.

[0013] The upper transparent electrode and the transparent electrode array together constitute the driving electrode of the liquid crystal layer, and apply voltage to the liquid crystal layer to drive it;

[0014] The liquid crystal material of the liquid crystal layer is nematic liquid crystal, and the upper alignment film and the lower alignment film make the nematic liquid crystal molecules in the liquid crystal layer oriented and arranged;

[0015] Preferably, the liquid crystal phase control array consists of N×N liquid crystal phase control units; the transparent electrode array consists of N×N electrode units; and a liquid crystal phase control unit in the liquid crystal phase control array corresponds to an electrode unit in the transparent electrode array.

[0016] Preferably, by controlling the driving voltage applied to each electrode unit in the transparent electrode array, the long axis pointing inclination angle of the nematic phase liquid crystal molecules in the liquid crystal phase control unit is modulated, thereby modulating the equivalent refractive index of the liquid crystal phase control unit.

[0017] Different driving voltages are applied to the electrode units corresponding to the liquid crystal phase control units. Assuming that the driving voltage applied to the electrode unit corresponding to the (i, j)th liquid crystal phase control unit is V(i, j), then the long axis pointing inclination angle of the liquid crystal molecules in the (i, j)th liquid crystal phase control unit is θ(i, j);

[0018] Therefore, the extraordinary light refractive index corresponding to the (i, j)th liquid crystal phase control unit is:

[0019]

[0020] The equivalent refractive index is

[0021] Where i = 0, 1, ... N-1; j = 0, 1, ... N-1; n o 、n e are the refractive indices of ordinary light and extraordinary light in nematic liquid crystal when there is no voltage, respectively.

[0022] Preferably, the linearly polarized light beam travels through different optical paths when transmitting in different liquid crystal phase control units. The optical path of the linearly polarized light beam when transmitting in the (i, j)th liquid crystal phase control unit is: OP(i, j) = n(i, j)L

[0023] Wherein, L is the thickness of the liquid crystal layer.

[0024] Preferably, the liquid crystal optical switch array is composed of N×N liquid crystal optical switch units;

[0025] The driving voltage is used to control the opening or closing of each liquid crystal optical switch unit, thereby realizing the gating of different light field units in the linearly polarized light beam;

[0026] Keep the liquid crystal light switch unit corresponding to the light field unit of the liquid crystal phase control unit (i, j) = (0, 0) in the open state, that is, keep the liquid crystal light switch unit (i, j) = (0, 0) in the open state, while keeping the other liquid crystal light switch units in the closed state.

[0027] Then, the remaining liquid crystal light switch units are turned on in a row-by-row and column-by-column direction, and only one liquid crystal light switch unit other than (i, j) = (0, 0) is kept in the turned-on state at each moment.

[0028] When i≠0, j≠0: the (0,0)th liquid crystal light switch unit and the (i,j)th liquid crystal light switch unit are controlled to be in the open state. At the same time, only two light beams from different light field units are incident on the detector system.

[0029] Preferably, the detector system comprises: a focusing mirror and a single point detector;

[0030] After the two beams of light from different light field units are converged by the focusing mirror, they are incident on the single point detector to interfere with each other to form an interference beam, and an interference pattern sequence is obtained;

[0031] When the two beams of the (i, j)th light field unit interfere with the two beams of the (0, 0)th light field unit, the optical path difference between the two coherent beams is:

[0032] δ(i,j)=[n(i,j)-n(0,0)]L

[0033] The spectral information of the linearly polarized light beam is obtained by performing discrete Fourier transform demodulation on the interference pattern sequence.

[0034] Preferably, the refractive index difference Δn between two adjacent liquid crystal phase control units in the liquid crystal phase control array is: n(i,j)=n(0,0)+Δn(jN+i)

[0035] Among them, λ min is the minimum wavelength in a linearly polarized beam.

[0036] The present invention also provides a measurement method of a liquid crystal spatial light modulation spectrometer, comprising the following steps:

[0037] S1, the light source system is used to emit a linearly polarized light beam incident on the liquid crystal phase control array;

[0038] S2, the linearly polarized light beam has a preset optical path difference after passing through the liquid crystal phase control array and is incident on the liquid crystal optical switch array;

[0039] S3, controlling N×N liquid crystal optical switch units in the liquid crystal optical switch array to achieve gating of different light field units in the linearly polarized light beam;

[0040] S4. At least two light field units with a preset optical path difference selected by the liquid crystal optical switch array enter the detector system and interfere with each other to obtain an interference pattern sequence, thereby acquiring spectral information of the linearly polarized light beam.

[0041] Compared to existing technologies, the present invention uses a liquid crystal phase control array to perform aperture segmentation and distributed phase modulation of the spatial light field, and a liquid crystal optical switch array to perform gated interferometry of the segmented light field units, achieving precise modulation of the optical path difference and accurate sampling of the interference signal. This patent proposes a Fourier transform spectrometer based on a liquid crystal phase control array and a liquid crystal optical switch array for precise scanning and energy splitting without optical path difference. This avoids the difficulties of manufacturing and controlling a scanning mirror, reduces the system's size and weight, and improves its energy efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 13 is a schematic structural diagram of a liquid crystal spatial light modulation spectrometer provided according to an embodiment of the present invention.

[0043] Figure 2 3 is a schematic structural diagram of a liquid crystal phase control array in a liquid crystal spatial light modulation spectrometer provided according to an embodiment of the present invention.

[0044] Figure 3 3 is a schematic structural diagram of a liquid crystal phase control unit in a liquid crystal spatial light modulation spectrometer provided according to an embodiment of the present invention.

[0045] Figure 4 Schematic diagram of the distribution of the applied driving voltage of the first liquid crystal phase control unit provided according to an embodiment of the present invention.

[0046] Figure 5 3 is a schematic diagram of the distribution of the applied driving voltage of the second liquid crystal phase control unit provided according to an embodiment of the present invention.

[0047] Figure 6 4 is a flow chart of a measurement method of a liquid crystal spatial light modulation spectrometer provided according to an embodiment of the present invention.

[0048] Figure 7 It is a flowchart of a measurement method of a liquid crystal spatial light modulation spectrometer provided according to an embodiment of the present invention.

[0049] The figures include: light source 1, collimator 2, polarizer 3, liquid crystal phase control array 4, liquid crystal light switch array 5, focusing mirror 6, single point detector 7, upper transparent substrate 8, upper transparent electrode 9, upper orientation film 10, liquid crystal layer 11, lower orientation film 12, transparent electrode array 13, lower transparent substrate 14, driving voltage 15 and nematic liquid crystal molecules 16. DETAILED DESCRIPTION

[0050] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In the following description, identical modules are denoted by identical reference numerals. In the case of identical reference numerals, their names and functions are also identical. Therefore, their detailed description will not be repeated.

[0051] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and do not constitute a limitation of the present invention.

[0052] Figure 1 3 is a schematic structural diagram of a liquid crystal spatial light modulation spectrometer provided according to an embodiment of the present invention.

[0053] like Figure 1As shown, the liquid crystal spatial light modulation spectrometer provided by the embodiment of the present invention includes: a light source system, a liquid crystal phase control array, a liquid crystal optical switch array and a detector system.

[0054] The light source system includes: a light source 1, a collimator 2 and a polarizer 3.

[0055] Light source 1 is used to emit a divergent light beam with a certain spectral radiation range. The divergent light beam is collimated by collimator 2 to form a parallel light beam, which is incident on polarizer 3. Polarizer 3 contains a polarizer whose polarization direction is parallel to the light incident plane. It converts the parallel light beam into linearly polarized light, which is incident on liquid crystal phase control array 4.

[0056] Figure 2 3 is a schematic structural diagram of a liquid crystal phase control array in a liquid crystal spatial light modulation spectrometer provided according to an embodiment of the present invention.

[0057] Figure 3 3 is a schematic structural diagram of a liquid crystal phase control unit in a liquid crystal spatial light modulation spectrometer provided according to an embodiment of the present invention.

[0058] like Figure 2 and Figure 3 As shown, the liquid crystal phase control array 4 is composed of N×N liquid crystal phase control units. The width of each liquid crystal phase control unit is a×a.

[0059] The liquid crystal phase control array 4 includes, from top to bottom, an upper transparent substrate 8, an upper transparent electrode 9, an upper orientation film 10, a liquid crystal layer 11, a lower orientation film 12, a transparent electrode array 13, a lower transparent substrate 14, a driving voltage 15 and nematic liquid crystal molecules 16.

[0060] The upper transparent substrate 8 serves as the optical window for the liquid crystal phase modulation array 4 and, together with the lower transparent substrate 14, forms a liquid crystal cell, securing the liquid crystal layer 11. The upper transparent substrate 8 is made of a transparent material such as glass, quartz, or sapphire, and has an antireflection coating on both its upper and lower surfaces.

[0061] The upper transparent electrode 9 and the transparent electrode array 13 together constitute the driving electrode of the liquid crystal layer 11, and apply voltage to drive the liquid crystal layer 11. The material of the upper transparent electrode 9 is indium tin oxide.

[0062] The upper alignment film 10 and the lower alignment film 12 together align the nematic liquid crystal molecules 16 in the liquid crystal layer 11 , and a polyimide polymer film may be used.

[0063] The liquid crystal material of the liquid crystal layer 11 is nematic liquid crystal. When no driving voltage is applied, the nematic liquid crystal molecules 16 are horizontally aligned in the device. When a driving voltage is applied, the long axes of the nematic liquid crystal molecules 16 point in the direction of the electric field, and the nematic liquid crystal molecules 16 stand upright in the liquid crystal layer 11. The thickness of the entire liquid crystal layer is L.

[0064] The lower alignment film 12 and the upper alignment film 10 together align the nematic liquid crystal molecules 16 . The lower alignment film 12 can be made of a polyimide polymer film.

[0065] The transparent electrode array 13, together with the upper transparent electrode 9, forms the driving electrodes for the liquid crystal layer 11, applying voltage to the liquid crystal layer 11 for distributed drive. The electrodes of the transparent electrode array 13 are made of indium tin oxide and are formed on the lower transparent substrate 14 through photolithography and etching. Each electrode unit of the transparent electrode array 13 corresponds to a liquid crystal phase modulation unit.

[0066] The lower transparent substrate 14 and the upper transparent substrate 8 together form a liquid crystal cell, which fixes the liquid crystal layer 11 and transmits the linearly polarized light beam. The lower transparent substrate 14 is made of transparent materials such as glass, quartz, and sapphire, and has anti-reflection films evaporated on both the upper and lower surfaces of the lower transparent substrate 14.

[0067] Figure 4 Schematic diagram of the distribution of the applied driving voltage of the first liquid crystal phase control unit provided according to an embodiment of the present invention.

[0068] Figure 5 3 is a schematic diagram of the distribution of the applied driving voltage of the second liquid crystal phase control unit provided according to an embodiment of the present invention.

[0069] like Figure 4 and Figure 5 As shown, by controlling the driving voltage 15 loaded on each electrode unit in the transparent electrode array 13, the long axis pointing inclination angle of the nematic phase liquid crystal molecules 16 in each liquid crystal phase control unit is modulated, thereby achieving modulation of the equivalent refractive index of each liquid crystal phase control unit.

[0070] Different driving voltages are applied to the electrode units corresponding to the liquid crystal phase control units. Let the driving voltage applied to the electrode unit corresponding to the (i, j)th liquid crystal phase control unit be V(i, j).

[0071] The nematic liquid crystal molecules in the liquid crystal layer of the liquid crystal phase control unit loaded with different driving voltages have different long axis pointing tilt angles, and the long axis pointing tilt angle of the liquid crystal molecules in the (i, j)th liquid crystal phase control unit is θ(i, j).

[0072] Different liquid crystal molecule long axis pointing inclination angles correspond to different refractive indices. Therefore, the extraordinary light refractive index corresponding to the (i, j)th liquid crystal phase control unit is:

[0073]

[0074] The equivalent refractive index is

[0075] Among them, n o 、n e are the refractive indices of ordinary light and extraordinary light in nematic liquid crystal when there is no voltage, respectively.

[0076] Therefore, a linearly polarized light beam will travel through different optical path lengths when transmitting in different liquid crystal phase control units of the liquid crystal phase control array. The optical path traveled by the linearly polarized light beam when transmitting in the (i, j)th liquid crystal phase control unit is OP(i, j) = n(i, j)L.

[0077] The linearly polarized light beam emitted from the liquid crystal phase control array 4 is incident on the liquid crystal optical switch array 5 .

[0078] The liquid crystal optical switch array 5 is composed of N×N liquid crystal optical switch units, each of which corresponds to a specific light field unit formed by the liquid crystal phase control array 4. Each liquid crystal optical switch unit in the liquid crystal optical switch array 5 is turned on and off by a driving voltage, thereby achieving gating interference of the spatial light field unit of the linearly polarized light beam.

[0079] Keep the liquid crystal light switch unit corresponding to the light field unit of the liquid crystal phase control unit (i, j) = (0, 0) in the open state, that is, keep the liquid crystal light switch unit (i, j) = (0, 0) in the open state, while keeping the other liquid crystal light switch units in the closed state.

[0080] Then, the remaining liquid crystal light switch units are turned on in a row-by-row and column-by-column direction, and only one liquid crystal light switch unit other than (i, j) = (0, 0) is kept in the turned-on state at each moment.

[0081] Therefore, at each moment, only two light beams from different light field units are incident on the detector system.

[0082] The detector system includes a focusing lens 6 and a single-point detector 7 .

[0083] After the two beams of light from different light field units are converged by the focusing mirror 6, they are incident on the single point detector 7 to interfere with each other to form an interference beam. An interference pattern sequence is obtained, and the spectral information of the linearly polarized beam is obtained.

[0084] When the two beams of the (i, j)th light field unit interfere with the two beams of the (0, 0)th light field unit, the optical path difference between the two coherent beams is:

[0085] δ(i,j)=[n(i,j)-n(0,0)]L

[0086] Therefore, the intensity of the (i, j)th interference pattern signal is:

[0087]

[0088] Where ν is the wave number of the interference light signal. For light with a wavelength of λ, ν = 1 / λ.

[0089] By performing discrete Fourier transform demodulation on the interference pattern sequence, the spectral information of the linearly polarized light beam can be restored.

[0090] In order to achieve equal-interval sampling, adjacent liquid crystal phase control units of the liquid crystal phase control array have the same refractive index difference Δn.

[0091] The refractive index of each liquid crystal phase control unit of the liquid crystal phase control array increases step by step by Δn along the "Z" shape row by row and column by column, that is, n(i,j)=n(0,0)+Δn(jN+i).

[0092] At this time, the optical path difference sampling array is:

[0093] δ(i,j)=ΔnL(jN+i)

[0094] In order to avoid spectral aliasing during the spectrum restoration process, the optical path difference sampling interval must be less than or equal to twice the minimum wavelength of the optical signal, that is:

[0095]

[0096] Therefore, the refractive index difference between adjacent liquid crystal phase control units in the liquid crystal phase control array must satisfy the following relationship:

[0097]

[0098] Among them, λ min is the minimum wavelength in a linearly polarized beam.

[0099] At this point, the restored spectrum is in the form of:

[0100]

[0101] According to the discrete Fourier transform theory, the spectral resolution is the inverse of the maximum optical path difference, that is, Therefore, the thickness L of the liquid crystal layer of the liquid crystal phase control array satisfies the following relationship:

[0102]

[0103] At the same time, the number of sampling points needs to satisfy the relationship where n max 、n minare the maximum and minimum refractive index values ​​that the liquid crystal material can achieve, respectively.

[0104] In particular, the two-dimensional liquid crystal phase control array can also be replaced by two one-dimensional liquid crystal phase control arrays, and its technical characteristics are the same as those of the two-dimensional liquid crystal phase control array.

[0105] Figure 6 4 is a flow chart of a measurement method of a liquid crystal spatial light modulation spectrometer provided according to an embodiment of the present invention.

[0106] Figure 7 It is a flowchart of a measurement method of a liquid crystal spatial light modulation spectrometer provided according to an embodiment of the present invention.

[0107] like Figure 6 and 7 As shown, the liquid crystal spatial light modulation spectrometer measurement method provided by the embodiment of the present invention includes the following steps:

[0108] S1. The light source system is used to emit a linearly polarized light beam incident on the liquid crystal phase control array.

[0109] Fix the collimator to the platform base; use a divergent laser light source with a wavelength within the system's operating spectrum as the incident light. Adjust the distance between the laser light source and the collimator so that the laser light source's emission point is located at the front focal point of the collimator, and collimate the outgoing light into a parallel beam. Place a polarizer in the collimated parallel light path and align it centrally. Adjust the polarization direction of the polarizer in the polarizer and use an analyzer to detect the polarization direction of the parallel beam. If the polarization direction of the parallel beam is not parallel to the light incident plane, continue to adjust the polarization direction of the polarizer in the polarizer until the polarization direction of the parallel beam is parallel to the light incident plane, thereby obtaining a linearly polarized beam.

[0110] S2. After passing through the liquid crystal phase control array, the linearly polarized light beam has a preset optical path difference and is incident on the liquid crystal optical switch array.

[0111] Placing the liquid crystal phase control array in the transmission light path of the polarizer and performing center alignment;

[0112] Placing the liquid crystal optical switch array in the transmission light path of the liquid crystal phase control array and aligning the center thereof;

[0113] Adjust the angle of the liquid crystal light switch array so that the liquid crystal light switch array units correspond one to one with the liquid crystal phase control array units;

[0114] S3. Controlling N×N liquid crystal optical switch units in the liquid crystal optical switch array to achieve gating of different light field units in the linearly polarized light beam.

[0115] S4. At least two light field units with a preset optical path difference selected by the liquid crystal optical switch array enter the detector system and interfere with each other to obtain an interference pattern sequence, thereby acquiring spectral information of the linearly polarized light beam.

[0116] A focusing mirror is placed in the outgoing light path of the liquid crystal light switch array; a single-point detector is placed at the focal plane of the focusing mirror; the driving voltage of the liquid crystal light switch array is adjusted so that it can select any two light field units in the spatial light field array; the laser light source is replaced with a broadband light source; the driving voltage loaded on the liquid crystal phase control array unit is adjusted so that adjacent units have equal refractive index differences; and the driving voltage distribution on each unit of the liquid crystal phase control array is fixed.

[0117] Although the embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention.

[0118] The above specific embodiments of the present invention do not constitute a limitation on the scope of protection of the present invention. Any other corresponding changes and modifications made based on the technical concept of the present invention should be included in the scope of protection of the claims of the present invention.

Claims

1. A liquid crystal spatial light modulation spectrometer, characterized in that: include: Light source system, liquid crystal phase control array, liquid crystal optical switch array and detector system; The light source system is configured to emit a linearly polarized light beam that is incident on the liquid crystal phase control array. After the linearly polarized light beam passes through the liquid crystal phase control array, a light field array having a preset optical path difference is obtained. The liquid crystal optical switch array is configured to gate the light field array so that light beams corresponding to at least two different light field units in the light field array are incident on the detector system, causing interference to form an interference beam, thereby obtaining an interference pattern sequence and acquiring spectral information of the linearly polarized light beam. The liquid crystal phase control array includes a transparent electrode array, and the transparent electrode array is composed of N×N electrode units; The liquid crystal phase control array is composed of N×N liquid crystal phase control units; a liquid crystal phase control unit in the liquid crystal phase control array corresponds to an electrode unit in the transparent electrode array; By controlling the driving voltage applied to each electrode unit in the transparent electrode array, the long axis pointing inclination angle of the nematic phase liquid crystal molecules in the liquid crystal phase control unit is modulated, thereby modulating the equivalent refractive index of the liquid crystal phase control unit; Different driving voltages are applied to the electrode units corresponding to the liquid crystal phase control units. Assuming that the driving voltage applied to the electrode unit corresponding to the (i, j)th liquid crystal phase control unit is V(i, j), then the long axis pointing inclination angle of the liquid crystal molecules of the (i, j)th liquid crystal phase control unit is θ(i, j); Therefore, the extraordinary light refractive index corresponding to the (i, j)th liquid crystal phase control unit is: The equivalent refractive index is ; Where i=0,1,…N-1; j=0,1,…N-1; n o 、n e are the refractive indices of ordinary light and extraordinary light in nematic liquid crystal when there is no voltage, respectively; The refractive index difference between two adjacent liquid crystal phase control units in the liquid crystal phase control array for: ， Among them, λ min is the minimum wavelength in the linearly polarized light beam; The liquid crystal light switch array is composed of N×N liquid crystal light switch units. Each liquid crystal light switch unit is controlled to be turned on or off by a driving voltage, thereby achieving gating of different light field units in the linearly polarized light beam. The liquid crystal light switch unit corresponding to the light field unit of the liquid crystal phase control unit (i, j)=(0, 0) is kept in an on state, that is, the liquid crystal light switch unit (i, j)=(0, 0) is kept in an on state, while the remaining liquid crystal light switch units are kept in an off state. The remaining liquid crystal light switch units are then turned on in a row-by-row and column-by-column direction, and only one liquid crystal light switch unit other than (i, j)=(0, 0) is kept in an on state at each moment. When i≠0 and j≠0, the (0, 0)th liquid crystal light switch unit and the (i, j)th liquid crystal light switch unit are controlled to be in an on state, so that at the same time, only two light beams from different light field units are incident on the detector system.

2. The liquid crystal spatial light modulation spectrometer according to claim 1, characterized in that: The light source system includes: a light source, a collimator and a polarizer; The light source is used to emit a divergent light beam, which is collimated by the collimator to form a parallel light beam and is incident on the polarizer; the polarizer converts the parallel light beam into linearly polarized light and is incident on the liquid crystal phase control array.

3. The liquid crystal spatial light modulation spectrometer according to claim 2, characterized in that: The liquid crystal phase control array includes, from top to bottom, an upper transparent substrate, an upper transparent electrode, an upper alignment film, a liquid crystal layer, a lower alignment film and a lower transparent substrate; The upper transparent substrate and the lower transparent substrate together form a liquid crystal cell to fix the liquid crystal layer; The upper and lower surfaces of the upper transparent substrate and the lower transparent substrate are coated with antireflection films; The upper transparent electrode and the transparent electrode array together constitute the driving electrode of the liquid crystal layer, and apply voltage to the liquid crystal layer to drive it; The liquid crystal material of the liquid crystal layer is nematic liquid crystal, and the upper alignment film and the lower alignment film align the nematic liquid crystal molecules in the liquid crystal layer.

4. The liquid crystal spatial light modulation spectrometer according to claim 2, characterized in that: The linearly polarized light beam travels through different optical path lengths when transmitting in different liquid crystal phase control units. The optical path length of the linearly polarized light beam when transmitting in the (i, j)th liquid crystal phase control unit is: Wherein, L is the thickness of the liquid crystal layer.

5. The liquid crystal spatial light modulation spectrometer according to claim 1, characterized in that: The detector system includes: a focusing mirror and a single point detector; After the light beams from two different light field units are converged by the focusing mirror, they are incident on the single point detector to interfere with each other to form interference beams, thereby obtaining an interference pattern sequence; When the two beams of the (i, j)th light field unit interfere with the two beams of the (0, 0)th light field unit, the optical path difference between the two coherent beams is: The spectrum information of the linearly polarized light beam is obtained by performing discrete Fourier transform demodulation on the interference pattern sequence.

6. A measurement method for a liquid crystal spatial light modulation spectrometer according to any one of claims 1 to 5, characterized in that: The following steps are involved: S1, the light source system is used to emit a linearly polarized light beam incident on the liquid crystal phase control array; S2, the linearly polarized light beam has a preset optical path difference after passing through the liquid crystal phase control array and is incident on the liquid crystal optical switch array; S3, controlling N×N liquid crystal optical switch units in the liquid crystal optical switch array to achieve gating of different light field units in the linearly polarized light beam; S4. At least two light field units with a preset optical path difference selected by the liquid crystal optical switch array enter the detector system and interfere with each other to obtain an interference pattern sequence, thereby acquiring spectral information of the linearly polarized light beam.

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