A method and system for testing phase modulation performance of a spatial light modulator

Abstract

The application discloses a kind of spatial light modulator phase modulation performance test method and system, belong to the measurement field of spatial light modulator, comprising: S1, generate a gray scale value in 0-255 gray scale interval and present uniform gradient variation gray scale image;S2, the gray scale image is loaded on the spatial light modulator to be measured, and the gray scale value modulation interval of spatial light modulator to be measured is modulated to 0-255, with the gray scale image drives spatial light modulator to be measured to carry out phase modulation to wave front under given incident wavelength;S3, after the wave front after phase modulation is diffracted into multiple diffracted beams, the multiple diffracted beams are coherent superposition, form transverse shear interference figure;S4, the transverse shear interference figure is collected, and wave front reconstruction is carried out to obtain wave front figure;Phase distribution data extraction is carried out to the wave front figure, and the gray scale-phase modulation curve of spatial light modulator to be measured is obtained.The application has the advantages of high measurement accuracy, simple structure of measurement system, strong anti-interference, fast and the like.

Description

Technical Field

[0001] This invention belongs to the field of spatial light modulator measurement, and more specifically, relates to a method and system for testing the phase modulation performance of spatial light modulators. Background Technology

[0002] Spatial light modulators, as wavefront phase modulation devices, have wide applications in imaging and display, among other fields. Under the control of an electrically driven signal, they alter parameters such as the amplitude or intensity, phase, coherence, or polarization state of light distribution in space, resulting in corresponding changes in wavefront characteristics, which are then used for wavefront modulation and correction. Because the phase modulation capability and modulation characteristics of each spatial light modulator differ, and even the phase modulation capability of the same spatial light modulator varies under different wavelength light sources, it is necessary to test the phase modulation performance of the spatial light modulator before applying it to wavefront modulation and correction.

[0003] Common performance measurement methods typically involve acquiring multiple interferometric images and demodulating the corresponding phase modulation information from them. This method is relatively slow and complex; for example, the Thyman-Green interferometer method. Other methods, such as the double-slit interferometry, require the fabrication of two high-precision masks, strict coaxiality of the optical path, and have poor system anti-interference capabilities. Summary of the Invention

[0004] In view of the shortcomings of the existing technology and the need for improvement, the present invention provides a method and system for testing the phase modulation performance of a spatial light modulator, the purpose of which is to improve the speed of phase modulation performance testing.

[0005] To achieve the above objectives, according to one aspect of the present invention, a method for testing the phase modulation performance of a spatial light modulator is provided, comprising:

[0006] S1. Generate a grayscale image with a uniform gradient change in grayscale value within the grayscale range of 0-255.

[0007] S2. Load the grayscale image onto the spatial light modulator under test, and modulate the grayscale value modulation range of the spatial light modulator under test to 0-255. Use the grayscale image to drive the spatial light modulator under test to perform phase modulation on the wavefront at a given incident wavelength.

[0008] S3. The phase-modulated wavefront is diffracted and then split into multiple diffracted beams. The multiple diffracted beams are coherently superimposed to form a transverse shearing interference pattern.

[0009] S4. Acquire the transverse shearing interferogram and perform wavefront reconstruction to obtain a wavefront image; extract phase distribution data from the wavefront image to obtain the gray-phase modulation curve of the spatial light modulator under test, so as to determine whether the curve satisfies a linear relationship at a specific wavelength.

[0010] Further, in S1, the grayscale image is a concentric ring grayscale image, which includes 255 rings;

[0011] Among them, the gray value of the central ring is 0, the gray value of the outermost ring is 255, and the gray value of the rings between the central ring and the outermost ring shows a continuous increasing gradient change in the gray value range of 0-255.

[0012] Alternatively, the grayscale value of the central ring is 255, the grayscale value of the outermost ring is 0, and the grayscale value of the rings between the central ring and the outermost ring shows a continuous decreasing gradient change within the grayscale range of 255-0.

[0013] Furthermore, the grayscale image is a grayscale image in which the grayscale value changes uniformly from top to bottom within the grayscale range of 0-255.

[0014] Alternatively, the grayscale image is a grayscale image in which the grayscale value changes uniformly from left to right within the grayscale range of 0-255.

[0015] Further, in S4, the transverse shearing interferogram is acquired and wavefront reconstruction is performed to obtain a wavefront image, including:

[0016] S41. Perform a Fourier transform on the transverse shearing interferogram to obtain a Fourier domain spectrum.

[0017] S42. Extract ±1 order spectrum points in different directions from the spectrum graph in the Fourier domain, and perform inverse Fourier transform on the ±1 order spectrum points to obtain wavefront phase gradient information in the corresponding directions.

[0018] S43. Perform phase gradient integral calculation on the wavefront phase gradient information to obtain the wavefront map.

[0019] Further, in S4, phase distribution data is extracted from the wavefront image to obtain the gray-phase modulation curve of the spatial light modulator under test, including:

[0020] For each gray value in the wavefront image, the phase corresponding to the same gray value is averaged to obtain the gray-phase modulation curve.

[0021] Furthermore, in S4, N transverse shearing interferograms are repeatedly acquired, and wavefront reconstruction is performed to obtain N sets of wavefront images;

[0022] Phase distribution data are extracted from the N groups of wavefront images to obtain the corresponding gray-phase modulation curves.

[0023] The phase modulation amount corresponding to the same gray value in the N sets of corresponding gray-phase modulation curves is averaged to obtain the gray-phase modulation curve of the spatial light modulator under test.

[0024] Furthermore, it also includes the steps of: modulating the grayscale value modulation range of the spatial light modulator under test to 0-0, and acquiring the corresponding transverse shearing interferogram, and using the transverse shearing interferogram as the background light;

[0025] S4 also includes the step of: subtracting the background light from the wavefront image and then extracting the phase distribution data.

[0026] According to another aspect of the present invention, a spatial light modulator phase modulation performance testing system is provided, for performing the spatial light modulator phase modulation performance testing method according to any one of the first aspects, comprising:

[0027] The image generation module is used to generate a grayscale image with a uniform gradient change in grayscale value within the grayscale range of 0-255.

[0028] The wavefront phase modulation module is used to load the grayscale image onto the spatial light modulator under test, and modulate the grayscale value modulation range of the spatial light modulator under test to 0-255, and use the grayscale image to drive the spatial light modulator under test to perform phase modulation on the wavefront at a given incident wavelength.

[0029] The transverse shearing interferogram generation module is used to split the phase-modulated wavefront diffracted beam into multiple diffracted beams, which are coherently superimposed to form a transverse shearing interferogram.

[0030] The performance testing module is used to acquire the transverse shearing interferogram and perform wavefront reconstruction to obtain a wavefront image; the phase distribution data of the wavefront image is extracted to obtain the gray-phase modulation curve of the spatial light modulator under test, so as to determine whether the curve satisfies a linear relationship at a specific wavelength.

[0031] Furthermore, in the wavefront phase modulation module, a wavefront at the given incident wavelength is generated by a wavefront generation unit, which sequentially comprises the following components along the optical path:

[0032] The device comprises a laser, a variable grayscale filter, a beam expander, and a linear polarizer, wherein the linear polarizer is parallel to the long axis of the spatial light modulator under test.

[0033] Furthermore, the transverse shearing interferogram generation module includes a two-dimensional diffraction grating or a DMD mirror;

[0034] In the performance testing module, the transverse shearing interferogram is acquired using a CCD camera.

[0035] In summary, the above-described technical solutions conceived in this invention can achieve the following beneficial effects:

[0036] (1) The spatial light modulator phase modulation performance testing method of the present invention generates only one grayscale image with a uniform gradient trend in the grayscale range of 0 to 255 as the driving image of the spatial light modulator under test, performs phase modulation on the wavefront corresponding to the given incident wavelength, and collects interference information on the modulated wavefront, thereby reconstructing the grayscale and phase modulation curve. Since the phase modulation amount corresponding to each grayscale value is the same, the phase corresponding to all grayscale values ​​can be demodulated from one grayscale driving image, that is, the grayscale and phase modulation curve is obtained. Compared with the existing method that can only load one grayscale value in one image and requires the acquisition of multiple interference images and the demodulation of the corresponding phase modulation information from the acquired multiple interference images, the method of the present invention greatly improves the speed of phase modulation performance testing and the testing method is simple.

[0037] (2) The method of the present invention divides the phase-modulated wavefront into multiple diffracted beams after diffraction. It is a common-path interference design, which does not require a reference wavefront, has strong anti-interference ability, and can quickly and accurately obtain the phase distribution of the wavefront.

[0038] (3) Preferably, the generated grayscale image can be a concentric ring grayscale image, or a grayscale driven image in which the grayscale value changes uniformly and continuously in the grayscale range of 0-255 from top to bottom or from left to right, which has a wide range of applications.

[0039] (4) By efficiently and repeatedly acquiring N transverse shearing interferograms, the number of samples is increased, measurement errors are reduced, and measurement accuracy is improved.

[0040] (5) By acquiring a background light and subtracting the background light from the obtained wavefront phase distribution map, the phase difference introduced by noise and other light sources can be reduced, thereby improving the accuracy of wavefront reconstruction.

[0041] (6) Preferably, when the distance Z between the CCD camera and the two-dimensional diffraction grating satisfies a specific relationship, the periodicity of the beam propagation can be observed after the beam passes through the two-dimensional diffraction grating, thereby improving the effect of the acquired interference pattern. Attached Figure Description

[0042] Figure 1 This is a schematic diagram of the spatial light modulator phase modulation performance testing method of the present invention.

[0043] Figure 2 This is a grayscale image of the concentric rings in an embodiment of the present invention.

[0044] Figure 3 This is another concentric ring grayscale image in an embodiment of the present invention.

[0045] Figure 4 This is a grayscale image with a continuous grayscale level change from top to bottom in an embodiment of the present invention.

[0046] Figure 5 This is a four-wave transverse shearing interferogram acquired by CCD in an embodiment of the present invention.

[0047] Figure 6 This is a spectrum of the Fourier domain obtained in an embodiment of the present invention.

[0048] Figure 7 This is a schematic diagram of the spatial light modulator phase modulation performance testing system of the present invention.

[0049] Figure 8 This is a schematic diagram of a four-wave transverse shearing interference pattern obtained by diffracting a phase-modulated wavefront through a two-dimensional diffraction grating in an embodiment of the present invention.

[0050] Figure 9 This is a schematic diagram of the gray-scale-phase modulation curve obtained in an embodiment of the present invention. Detailed Implementation

[0051] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0052] like Figure 1 As shown, the spatial light modulator phase modulation performance testing method of the present invention mainly includes the following steps:

[0053] S1. Generate a grayscale image, in which the grayscale value changes uniformly in the grayscale range of 0-255.

[0054] S2. Load the grayscale image onto the spatial light modulator under test, and modulate the grayscale value modulation range of the spatial light modulator under test to 0-255. Use the grayscale image to drive the spatial light modulator under test to perform phase modulation on the wavefront corresponding to the given incident wavelength.

[0055] S3. The phase-modulated wavefront is diffracted and split into multiple diffracted beams; the multiple diffracted beams are coherently superimposed to form a transverse shearing interference pattern.

[0056] S4. Acquire the transverse shearing interferogram and perform wavefront reconstruction to obtain the wavefront phase distribution map; extract the phase distribution data from the wavefront phase distribution map to obtain the gray-phase modulation curve of the spatial light modulator under test at a specific wavelength, so as to determine whether the gray level and phase of the spatial light modulator under test satisfy a linear relationship at a specific wavelength.

[0057] Specifically, such as Figure 2 As shown in S1, the generated grayscale image can be a concentric ring grayscale image, which includes 255 rings. The grayscale value of the central ring is 0, the grayscale value of the outermost ring is 255, and the grayscale values ​​of the rings between the central ring and the outermost ring are continuously increasing in the grayscale range of 0-255, that is, 1, 2..., 254 in sequence.

[0058] Or, such as Figure 3 As shown, in the grayscale image of the concentric rings, the grayscale value of the central ring is 255, the grayscale value of the outermost ring is 0, and the grayscale values ​​of the rings between the central ring and the outermost ring show a continuous decreasing gradient change in the grayscale range of 255-0, that is, 254, 253, ..., 1 in sequence.

[0059] Or, such as Figure 4 As shown, in S1, the generated grayscale image can be a grayscale driven image with a uniform and continuous grayscale level change from top to bottom within the grayscale range of 0-255, and the trend of the grayscale level change can be sequentially increasing or sequentially decreasing. In other embodiments, the generated grayscale image can be a grayscale driven image with a uniform and continuous grayscale level change from left to right between 0-255. In this embodiment of the invention, the following is used: Figure 2 The concentric ring grayscale image shown has a diameter of 100 pixels and a width of 512 pixels. In this embodiment of the invention, one grayscale value represents two pixels. In other embodiments, grayscale images of other sizes can be selected according to actual needs.

[0060] Specifically, in S3, in this embodiment of the invention, the phase-modulated wavefront is diffracted and divided into four diffracted beams. The four diffracted beams are coherently superimposed to form a four-wave transverse shearing interference pattern.

[0061] Specifically, in S4, the transverse shearing interferogram is acquired, and wavefront reconstruction is performed to obtain the wavefront phase distribution map, including:

[0062] S41. Perform a Fourier transform on the acquired transverse shearing interferogram to obtain the Fourier domain spectrum.

[0063] S42. Extract ±1st order spectral points in different directions from the Fourier domain spectrogram, and perform inverse Fourier transform on these ±1st order spectral points to obtain the wavefront phase gradient information in the corresponding directions; wherein, the ±1st order spectral points are also the first-order diffraction spots, and the first-order diffraction spots contain wavefront contour-related information. In this embodiment of the invention, ±1st order spectral points in the x and y directions are extracted, and inverse Fourier transform is performed to extract the wavefront phase gradient information corresponding to the x and y directions.

[0064] S43. Perform phase gradient integral calculation on the wavefront phase gradient information in the corresponding direction to complete wavefront reconstruction and obtain the wavefront phase distribution map corresponding to the transverse shearing interferogram.

[0065] Preferably, in step S4, N transverse shearing interferograms are repeatedly acquired and wavefront reconstructed to obtain N sets of corresponding wavefront phase distribution maps. Repeatedly acquiring N transverse shearing interferograms increases the sample size, avoids repetition errors, and improves measurement accuracy. In this embodiment, N = 100, and 100 four-wave transverse shearing interferograms are acquired, as shown... Figure 5 As shown; Fourier transforms were performed on 100 sets of interferograms to obtain the corresponding Fourier domain spectrum for each set, as shown. Figure 6 As shown.

[0066] Specifically, in S4, phase distribution data is extracted from the wavefront phase distribution map to obtain the gray-phase modulation curve of the spatial light modulator under test at a specific wavelength, including:

[0067] For each gray value in the obtained wavefront phase distribution map, the phase corresponding to the same gray value is averaged to obtain the relationship between the gray value and the corresponding phase modulation information, i.e., the gray-phase modulation curve.

[0068] If there are N sets of wavefront phase distribution maps, then the phase distribution data of each set of wavefront phase distribution maps is extracted to obtain N sets of corresponding gray-scale-phase modulation curves; the phase modulation amount corresponding to the same gray value in the N sets of gray-scale-phase modulation curves is averaged to obtain the gray-scale-phase modulation curve of the spatial light modulator under test.

[0069] If the gray-phase modulation curve does not satisfy the linear relationship at a specific wavelength, then the spatial light modulator under test is linearly corrected.

[0070] Preferably, the method further includes the following steps: adjusting the grayscale modulation range of the grayscale image on the spatial light modulator under test to 0-0, and then acquiring the corresponding transverse shearing interferogram as the background light; subtracting the background light from the obtained wavefront phase distribution map or N sets of obtained wavefront phase distribution maps respectively, and extracting the phase distribution data from the resulting wavefront map to obtain the phase and grayscale curves of the spatial light modulator under test at a specific wavelength. This can reduce the influence of system noise and ambient light on the wavefront reconstruction accuracy. Because when the grayscale modulation range of the spatial light modulator under test is adjusted to 0-0, it is equivalent to having no phase drive. Under the same conditions, the phase information carried in the acquired background light at this time only includes system noise and ambient light information.

[0071] The spatial light modulator phase modulation performance testing method of the present invention uses only one grayscale image with a uniform gradient trend of grayscale values ​​in the grayscale range of 0 to 255 as the driving image of the spatial light modulator under test. Phase modulation is performed on the wavefront corresponding to the given incident wavelength, and interference information is collected on the modulated wavefront. Then, the grayscale and phase modulation curves are reconstructed. Since the phase modulation amount corresponding to each grayscale value is the same, the phase corresponding to all grayscale values ​​can be demodulated from a single grayscale driving image, which is the grayscale and phase modulation curve. Compared with the existing method that can only load one grayscale value in a single image and requires the acquisition of multiple interference images and the demodulation of the corresponding phase modulation information from the acquired multiple interference images, the method of the present invention greatly improves the speed of phase modulation performance testing, and the testing method is simple and can realize high-efficiency measurement of the phase modulation capability of spatial light modulators.

[0072] Based on the above-described method for testing the phase modulation performance of spatial light modulators, this invention also provides a corresponding system for testing the phase modulation performance of spatial light modulators, mainly comprising:

[0073] The image generation module is used to generate a grayscale image whose grayscale value changes uniformly in the grayscale range of 0-255.

[0074] The wavefront phase modulation module is used to load the grayscale image onto the spatial light modulator under test and modulate the grayscale value modulation range of the spatial light modulator under test to 0-255. The grayscale image is used to drive the spatial light modulator under test to perform phase modulation on the wavefront corresponding to the given incident wavelength.

[0075] The transverse shearing interferogram generation module is used to diffract the phase-modulated wavefront and split it into multiple diffracted beams; the multiple diffracted beams are coherently superimposed to form a transverse shearing interferogram.

[0076] The performance testing module is used to acquire the transverse shearing interferogram and perform wavefront reconstruction to obtain the wavefront phase distribution map; the phase distribution data of the wavefront phase distribution map is extracted to obtain the gray-phase modulation curve of the spatial light modulator under test at a specific wavelength, so as to determine whether the gray level and phase of the spatial light modulator under test satisfy a linear relationship at a specific wavelength.

[0077] Each module is used to implement the steps corresponding to the above spatial light modulator phase modulation performance testing method. For specific implementation methods, please refer to the detailed description in the above embodiments.

[0078] Specifically, such as Figure 7 , Figure 8 As shown, in the wavefront phase modulation module, a wavefront corresponding to a given incident wavelength is generated by a wavefront generation unit. This wavefront generation unit includes, along the optical path, the following components in sequence:

[0079] The system includes a laser, a variable grayscale filter (NDL), a beam expander, and a linear polarizer. The linear polarizer is parallel to the long axis of the spatial light modulator (SLM) under test, making the SLM a pure phase modulator.

[0080] A laser is used to emit a laser beam with a specific incident wavelength;

[0081] Variable grayscale filters (NDL) are used to attenuate the intensity of laser beams at specific incident wavelengths.

[0082] Beam expanders are used to expand and collimate a laser beam that has been attenuated in intensity into parallel light.

[0083] Linear polarizers are used to convert parallel light after beam expansion and collimation into linearly polarized light, forming a wavefront corresponding to a given incident wavelength. This wavefront corresponding to the given incident wavelength is transmitted to the spatial light modulator under test for wavefront phase modulation.

[0084] In embodiments of the present invention, such as Figure 7 As shown, the beam expander consists of convex lens L1 and convex lens L2. The linear polarizer includes linear polarizer P1 and linear polarizer P2. Linear polarizer P1 is used to convert parallel light into linearly polarized light, and linear polarizer P2 is used to check whether the light emitted from the spatial light modulator under test is parallel to the linearly polarized light.

[0085] Specifically, the transverse shearing interferogram generation module includes a two-dimensional diffraction grating or a DMD mirror; in this embodiment of the invention, the phase-modulated wavefront is passed through a two-dimensional diffraction grating, causing a diffraction effect that splits the wavefront into four diffraction beams. The four diffraction beams are coherently superimposed to form a four-wave transverse shearing interferogram, such as... Figure 8 As shown.

[0086] Specifically, in the performance testing module, a transverse shearing interferogram is acquired using a CCD camera. In this embodiment of the invention, the sampling interval of the CCD camera is set to 2 seconds.

[0087] Preferably, in this embodiment of the invention, in order to allow the periodicity of the beam propagation to be observed after the beam has been diffracted by the two-dimensional diffraction grating, the distance Z between the CCD camera and the two-dimensional diffraction grating satisfies:

[0088] z = 2T 2 / λ0

[0089] Where T represents the period of the two-dimensional diffraction grating, and λ0 is the specific incident wavelength emitted by the laser.

[0090] Based on the aforementioned spatial light modulator phase modulation performance testing system, in this embodiment of the invention, a spatial light modulator of model HDSLM80R was used to measure its modulation characteristics. This model of spatial light modulator operates at wavelengths of 420-1100 nm, and the two-dimensional diffraction grating operates at wavelengths of 400-1050 nm. The laser wavelength used in the experiment was 632.8 nm. The phase modulation curve of the spatial light modulator measured in the experiment is shown below. Figure 9 As shown, since the spatial light modulator is calibrated at the factory under a 632.8nm light source, this model of spatial light modulator exhibits obvious linear characteristics in phase modulation at a working wavelength of 632.8nm, and the phase modulation depth of the liquid crystal spatial light modulator reaches 2π.

[0091] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for testing the phase modulation performance of a spatial light modulator, characterized in that, include: S1. Generate a grayscale image with a uniform gradient change in grayscale value within the grayscale range of 0-255. S2. Load the grayscale image onto the spatial light modulator under test, and modulate the grayscale value modulation range of the spatial light modulator under test to 0-255. Use the grayscale image to drive the spatial light modulator under test to perform phase modulation on the wavefront at a given incident wavelength. S3. The phase-modulated wavefront diffracted beams are split into multiple diffracted beams, which are coherently superimposed under common optical path conditions to form a transverse shearing interference pattern. S4. Acquire the transverse shearing interferogram and perform a Fourier transform on the transverse shearing interferogram to extract wavefront phase gradient information. Based on the wavefront phase gradient information, obtain a reconstructed wavefront image. Extract phase distribution data from the wavefront image to obtain the gray-phase modulation curves corresponding to all gray values ​​in the 0-255 gray range of the spatial light modulator under test in one go, so as to determine whether the curves satisfy a linear relationship at a specific wavelength.

2. The method according to claim 1, characterized in that, In S1, the grayscale image is a concentric ring grayscale image, which includes 255 rings; Among them, the gray value of the central ring is 0, the gray value of the outermost ring is 255, and the gray value of the rings between the central ring and the outermost ring shows a continuous increasing gradient change in the gray value range of 0-255. Alternatively, the grayscale value of the central ring is 255, the grayscale value of the outermost ring is 0, and the grayscale value of the rings between the central ring and the outermost ring shows a continuous decreasing gradient change within the grayscale range of 255-0.

3. The method according to claim 1, characterized in that, The grayscale image is a grayscale image in which the grayscale value changes uniformly from top to bottom within the grayscale range of 0-255. Alternatively, the grayscale image is a grayscale image in which the grayscale value changes uniformly from left to right within the grayscale range of 0-255.

4. The method according to claim 1, characterized in that, In S4, the transverse shearing interferogram is acquired, and wavefront reconstruction is performed to obtain the wavefront image, including: S41. Perform a Fourier transform on the transverse shearing interferogram to obtain a Fourier domain spectrum. S42. Extract ±1 order spectrum points in different directions from the spectrum graph in the Fourier domain, and perform inverse Fourier transform on the ±1 order spectrum points to obtain wavefront phase gradient information in the corresponding directions. S43. Perform phase gradient integral calculation on the wavefront phase gradient information to obtain the wavefront map.

5. The method according to claim 4, characterized in that, In S4, phase distribution data is extracted from the wavefront image to obtain the gray-scale-phase modulation curve of the spatial light modulator under test, including: For each gray value in the wavefront image, the phase corresponding to the same gray value is averaged to obtain the gray-phase modulation curve.

6. The method according to claim 5, characterized in that, In S4, N transverse shearing interferograms are repeatedly acquired, and wavefront reconstruction is performed to obtain N sets of wavefront images. Phase distribution data are extracted from the N groups of wavefront images to obtain the corresponding gray-phase modulation curves. The phase modulation amount corresponding to the same gray value in the N sets of corresponding gray-phase modulation curves is averaged to obtain the gray-phase modulation curve of the spatial light modulator under test.

7. The method according to claim 1, characterized in that, The method also includes the following steps: modulating the grayscale value modulation range of the spatial light modulator under test to 0-0, and acquiring the corresponding transverse shearing interferogram, using the transverse shearing interferogram as the background light; S4 also includes the step of: subtracting the background light from the wavefront image and then extracting the phase distribution data.

8. A spatial light modulator phase modulation performance testing system, characterized in that, A method for performing the phase modulation performance test of a spatial light modulator according to any one of claims 1-7, comprising: The image generation module is used to generate a grayscale image with a uniform gradient change in grayscale value within the grayscale range of 0-255. The wavefront phase modulation module is used to load the grayscale image onto the spatial light modulator under test, and modulate the grayscale value modulation range of the spatial light modulator under test to 0-255, and use the grayscale image to drive the spatial light modulator under test to perform phase modulation on the wavefront at a given incident wavelength. The transverse shearing interferogram generation module is used to split the phase-modulated wavefront diffracted beam into multiple diffracted beams, which are coherently superimposed under common optical path conditions to form a transverse shearing interferogram. The performance testing module is used to acquire the transverse shearing interferogram and perform a Fourier transform on the transverse shearing interferogram to extract wavefront phase gradient information. Based on the wavefront phase gradient information, a reconstructed wavefront image is obtained. The phase distribution data of the wavefront image is extracted to obtain the gray-phase modulation curves corresponding to all gray values ​​in the 0-255 gray-level range of the spatial light modulator under test in one go, so as to determine whether the curves satisfy a linear relationship at a specific wavelength.

9. The system according to claim 8, characterized in that, In the wavefront phase modulation module, a wavefront at the given incident wavelength is generated by a wavefront generation unit, which includes, along the optical path, the following components: The device comprises a laser, a variable grayscale filter, a beam expander, and a linear polarizer, wherein the linear polarizer is parallel to the long axis of the spatial light modulator under test.

10. The system according to claim 8, characterized in that, The transverse shearing interferogram generation module includes a two-dimensional diffraction grating or a DMD reflector; In the performance testing module, the transverse shearing interferogram is acquired using a CCD camera.

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