Test method and test system for obtaining phase modulation curve of spatial light modulator

Abstract

The invention is applicable to the testing application field of a spatial light modulator, and discloses a testing method and a testing system for obtaining a phase modulation curve of a spatial light modulator. The testing method comprises: drawing a grayscale gradient diagram; building an optical path system, wherein a spatial light modulator of the optical path system performs phase modulation on structured light according to the grayscale value of the grayscale gradient diagram, and the phase-modulated structured light interferes with a reference light to form interference fringes; collecting interference fringes to generate an interference fringes image; processing the interference fringes image to generate an interference fringes curve diagram; an information processing module outputs a grayscale phase curve according to information of the interference fringes curve diagram and the grayscale gradient diagram; in the test, the spatial light modulator can load a grayscale gradient diagram corresponding to a grayscale value within an interval value at one time, and the optical path system can output interference fringes corresponding to each grayscale value in the grayscale value within an interval value at one time, so that the processing speed and the test accuracy can be improved.

Description

Technical Field

[0001] The present invention relates to the field of testing applications of spatial light modulators, and in particular to a testing method and a testing system for obtaining a phase modulation curve of a spatial light modulator. Background Art

[0002] A spatial light modulator is a device that modulates the light field of a light wave. It can perform real-time spatial modulation of the phase, intensity, and polarization of a light beam in one-dimensional or two-dimensional distribution. It is widely used in the fields of optical information processing, beam transformation, and output display. A phase-type spatial light modulator is a type of spatial light modulator that has the function of continuously modulating the phase of a light wave under the drive of a variable electrical signal - phase modulation characteristics. This function directly affects the use effect of the device. Therefore, before use, the phase modulation obtained by the spatial light modulator needs to be tested to obtain the phase modulation curve. Commonly used measurement methods include diffraction and interference. The diffraction method is less affected by the external environment, but the calculation is more complicated. The interference method is mainly based on the principle of interference for measurement. Most of the measurement methods are to obtain the offset by interfering by loading different grayscale images to the spatial light modulator one by one. The operation is relatively complicated and is greatly affected by the environment. The subsequent data processing is also relatively complicated and the accuracy is not high.

[0003] Especially for batch detection of phase modulation curves of spatial light modulators in different bands, the above detection method has low efficiency and poor accuracy. Summary of the invention

[0004] A first object of the present invention is to provide a testing method for obtaining a phase modulation curve of a spatial light modulator, which can quickly and accurately obtain the grayscale phase curve of the spatial light modulator.

[0005] To achieve the above object, the solution provided by the present invention is:

[0006] A test method for obtaining a phase modulation curve of a spatial light modulator comprises the following steps:

[0007] Step S10, drawing a grayscale gradient map, the grayscale gradient map includes three regions, namely a first region, a second region and a third region, the grayscale value of the first region is 0, the grayscale value of the third region is a, 0≤a≤255, and the grayscale value of the second region increases by b from the first grayscale preset value until it increases to the second grayscale preset value, where b is an integer;

[0008] Step S20, constructing an optical path system for outputting structured light and reference light, wherein a spatial light modulator of the optical path system is used to load the grayscale gradient map, and phase modulate the structured light according to the grayscale value of the grayscale gradient map, so that the phase-modulated structured light interferes with the reference light to form interference fringes;

[0009] Step S30, collecting the interference fringes to generate an interference fringe image, wherein the interference fringe image includes an interference fringe image from the first grayscale preset value to the second grayscale preset value;

[0010] Step S40, performing a clearing and edge processing on the interference fringe image, and extracting a center line of the interference fringe image to generate an interference fringe curve graph;

[0011] Step S50: outputting a gray phase curve according to the information of the interference fringe curve graph and the gray gradient graph.

[0012] Preferably, in step S10, the first grayscale preset value is 0, the second grayscale preset value is 255, b is 1, and the grayscale value of the third area is 255.

[0013] Preferably, in step S10, when drawing the grayscale gradient map, the pixel size occupied by the second area is calculated according to the resolution size, and the resolution size is defined as M*N, the pixel size is d, the width of the first area and the third area are both L1, the width of the second area is D, and the number of pixels occupied by the second area is m, then

[0014]

[0015] D=md.

[0016] Preferably, the optical path system includes a laser, a beam expander, a polarizer, a beam splitter, a reflector, a spatial light modulator, a lens and an image acquisition device. The laser beam emitted by the laser is expanded by the beam expander. The expanded laser beam passes through the polarizer, and its polarization direction is adjusted to be parallel to the long axis direction of the liquid crystal of the spatial light modulator. The adjusted laser beam is vertically incident on the beam splitter prism and is divided into two mutually perpendicular first and second beams. The first beam is transmitted and vertically incident on the spatial light modulator. The first beam modulated by the spatial light modulator is reflected by the beam splitter prism and then passes through the lens to generate a structured light field as structured light. The second beam is reflected and vertically incident on the reflector, and is reflected by the reflector back to the beam splitter prism as a reference light. The reference light and the structured light converge at the beam splitter prism to interfere with each other, and are focused and imaged on the image acquisition device through the lens. The image acquisition device outputs an interference fringe image.

[0017] Preferably, in step S40, the implementation method of clarifying and edge processing the interference fringe image is: using an image smoothing algorithm to eliminate noise to enhance the interference fringe image; using image sharpening technology to make the edge of the interference fringe image clear.

[0018] Preferably, in step S50, according to the information of the interference fringe curve graph and the grayscale gradient graph, a specific implementation method of outputting the grayscale phase curve is:

[0019] The interference fringe curve and the grayscale gradient map are input into an information processing module. The information processing module uses the interference fringe curve of the first area as a reference, calculates the phase modulation amount corresponding to each grayscale value of the second area by using a phase model conversion method, and draws a grayscale phase curve with the grayscale value as the abscissa and the calculated phase modulation amount as the ordinate. The phase model conversion satisfies the following relationship:

[0020]

[0021] Among them, ∧ is the stripe period, is the phase modulation; δ is the fringe shift.

[0022] The second object of the present invention is to provide a test system for obtaining a phase modulation curve of a spatial light modulator, characterized in that the system for obtaining a phase modulation curve of a spatial light modulator includes an optical path system, an image processing module and an information processing module, the information processing module is used to output a grayscale gradient map, the optical path system outputs an interference fringe image according to the grayscale value corresponding to the grayscale gradient map, the image processing module is used to clarify and edge the interference fringe image, and to extract the center line of the processed interference fringe image to generate an interference fringe curve map, the information processing module receives the interference fringe curve map output by the image processing, and outputs a grayscale phase curve according to the information of the interference fringe curve map and the grayscale gradient map.

[0023] Preferably, the grayscale gradient map includes three areas, namely the first area, the second area and the third area. The grayscale value of the first area is 0, the grayscale value of the third area is a, 0≤a≤255, and the grayscale value of the second area increases by b from the first grayscale preset value until it increases to the second grayscale preset value, where b is an integer.

[0024] Preferably, the first grayscale preset value is 0, the second grayscale preset value is 255, b is 1, and the grayscale value of the third area is 255.

[0025] Preferably, the optical path system includes a laser, a beam expander, a polarizer, a beam splitter, a reflector, a spatial light modulator, a lens and an image acquisition device. The laser beam emitted by the laser is expanded by the beam expander. The expanded laser beam passes through the polarizer, and its polarization direction is adjusted to be parallel to the long axis direction of the liquid crystal of the spatial light modulator. The adjusted laser beam is vertically incident on the beam splitter prism and is divided into two mutually perpendicular first and second beams. The first beam is transmitted and vertically incident on the spatial light modulator. The first beam modulated by the spatial light modulator is reflected by the beam splitter prism and then passes through the lens to generate a structured light field as structured light. The second beam is reflected and vertically incident on the reflector, and is reflected by the reflector back to the beam splitter prism as a reference light. The reference light and the structured light converge at the beam splitter prism to interfere with each other, and are focused and imaged on the image acquisition device through the lens. The image acquisition device outputs an interference fringe image.

[0026] The present invention provides a test method for obtaining a phase modulation curve of a spatial light modulator. In the test, the spatial light modulator can load a grayscale gradient image corresponding to a grayscale value within an interval value at one time. Therefore, the optical path system can output interference fringes corresponding to each grayscale value in the grayscale value within the interval value at one time. Such a design can improve processing time and processing speed on the one hand, and avoid errors introduced by the environment and operation on the other hand, thereby improving test accuracy.

[0027] The present invention provides a test system for obtaining a phase modulation curve of a spatial light modulator. The spatial light modulator in the system can load a grayscale gradient map corresponding to grayscale values ​​within an interval value at one time. Therefore, the system can output interference fringes corresponding to each grayscale value in the grayscale value within an interval value at one time. Such a design can improve processing time and processing speed on the one hand, and avoid errors introduced by the environment and operation on the other hand, thereby improving test accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] 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 only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0029] Figure 1 is a flow chart of a test method for obtaining a phase modulation curve of a spatial light modulator provided by an embodiment of the present invention;

[0030] Figure 2 is a schematic structural diagram of an optical path system provided by an embodiment of the present invention;

[0031] Figure 3 It is a schematic diagram of the structure of a test system for obtaining a phase modulation curve of a spatial light modulator provided by an embodiment of the present invention.

[0032] Description of Figure Numbers:

[0033] 1. Laser; 2. Beam expander; 3. Polarizer; 4. Beam splitter; 5. Reflector; 6. Spatial light modulator; 7. Lens; 8. Image acquisition equipment. DETAILED DESCRIPTION

[0034] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0035] It should be noted that all directional indications in the embodiments of the present invention (such as up, down, left, right, front, back, etc.) are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0036] It should also be noted that when an element is referred to as being "fixed on" or "disposed on" another element, it may be directly on the other element or there may be an intermediate element at the same time. When an element is referred to as being "connected to" another element, it may be directly connected to the other element or there may be an intermediate element at the same time.

[0037] In addition, the descriptions of "first", "second", etc. in the present invention are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the ability of ordinary technicians in the field to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0038] like Figure 1 to Figure 2 As shown, it is a test method for obtaining a phase modulation curve of a spatial light modulator according to an embodiment of the invention.

[0039] See also Figure 1-Figure 2 The test method for obtaining the phase modulation curve of a spatial light modulator according to an embodiment of the present invention comprises the following steps:

[0040] Step S10, using the information processing module to draw a grayscale gradient map, the grayscale gradient map includes three areas, namely the first area, the second area and the third area, the grayscale value of the first area is 0, the grayscale value of the third area is a, 0≤a≤255, the grayscale value of the second area starts from the first grayscale preset value and gradually increases by b until it increases to the second grayscale preset value, b is an integer. The grayscale value of the second area can be tested and drawn according to actual needs.

[0041] In actual testing, it is generally necessary to test the phase modulation amount corresponding to the grayscale value of 0-255. Therefore, in this embodiment, the grayscale value of the third area is 255, the first grayscale preset value of the second area is 0, the second grayscale preset value is 255, and b is 1, that is, the grayscale value of the second area gradually increases from left to right, starting from 0, until the rightmost value is 255. Figure 2 As shown, in the grayscale gradient image, the first area displays black, the second area is a gradient color area, and the third area displays white.

[0042] Optionally, the information processing module includes image processing software Matlab, and the grayscale gradient map is directly drawn by the image processing software Matlab.

[0043] When drawing a grayscale gradient image, the pixel size of the second area is calculated according to the resolution size. The resolution size is defined as M*N, the pixel size is d, the width of the first area and the third area is L1, the width of the second area is D, and the number of pixels occupied by the second area is m.

[0044]

[0045] D=md.

[0046] Step S20, build an optical path system for outputting structured light and reference light. The spatial light modulator 6 of the optical path system is used to load the grayscale gradient map and phase modulate the structured light according to the grayscale value of the grayscale gradient map. The phase-modulated structured light interferes with the reference light to form interference fringes.

[0047] Step S30, collecting interference fringes to generate an interference fringe image, the interference fringe image includes an interference fringe image from a first grayscale preset value to a second grayscale preset value, and the interference fringes in the interference fringe image are alternately light and dark and are periodically arranged.

[0048] The optical path system includes a laser 1, a beam expander 2, a polarizer 3, a beam splitter 4, a reflector 5, a spatial light modulator 6, a lens 7 and an image acquisition device 8. The laser beam emitted by the laser 1 is expanded by the beam expander 2. The expanded laser beam passes through the polarizer 3, and its polarization direction is adjusted to be parallel to the long axis direction of the liquid crystal of the spatial light modulator. The adjusted laser beam is vertically incident on the beam splitter 4 and is divided into two mutually perpendicular first and second beams. The first beam is transmitted and vertically incident on the spatial light modulator 6. The first beam modulated by the spatial light modulator 6 is reflected by the beam splitter 4 and passes through the lens 7 to generate a structured light field as the structured light. The second beam is reflected and vertically incident on the reflector 5, and is reflected by the reflector 5 back to the beam splitter 4 as the reference light. The reference light and the structured light converge at the beam splitter 4 to interfere, and are focused and imaged on the image acquisition device 8 through the lens 7. The image acquisition device 8 outputs an interference fringe image.

[0049] The traditional test method is to load different grayscale images to the spatial light modulator 6 one by one (that is, if the grayscale value changes according to 1, if you want to load the grayscale value of 0-255, you need to load it 255 times) to obtain the offset through interference. The operation is relatively complicated and is greatly affected by the environment. The subsequent data processing is also relatively complicated and the accuracy is not high. However, the spatial light modulator 6 of this embodiment can load the grayscale gradient image corresponding to the grayscale value of 0-255 at one time. Therefore, the optical path system can output the interference fringes corresponding to each grayscale value in the grayscale value of 0-255 at one time. This design can improve the processing time and processing speed on the one hand, and avoid the errors introduced by the environment and operation on the other hand, and improve the test accuracy.

[0050] Step S40, performing clarity and edge processing on the interference fringe image, extracting the center line of the interference fringe, and generating an interference fringe curve graph.

[0051] Specifically, the implementation method of clarifying and edge processing the interference fringe image is as follows: first, using an image smoothing algorithm to eliminate noise to enhance the interference fringe image; then, using an image sharpening technique to make the edge of the interference fringe image clear.

[0052] like Figure 2As shown, four periods of interference fringe curves are exemplarily displayed, and the interference fringe curve of the first area portion corresponding to the grayscale gradient diagram is a smooth straight line, because the grayscale value of the spatial light modulator 6 corresponding to the interference fringe curve of the first area portion is a fixed value of 0, and the interference fringe curve of the third area portion is a smooth straight line, because the grayscale value of the spatial light modulator 6 corresponding to the interference fringe curve of the third area portion is a fixed value of 255, and the grayscale value of the spatial light modulator 6 corresponding to the interference fringe curve of the second area portion is a grayscale value varying from 0 to 255, therefore, the interference fringe curve of the second area portion is a smooth oblique line.

[0053] Step S50, outputting a gray phase curve according to the interference fringe curve diagram and the gray gradient diagram information. Specifically comprising:

[0054] The interference fringe curve and the grayscale gradient map are input into the information processing module. The information processing module calculates the phase modulation amount corresponding to each grayscale value of the second area based on the information of the interference fringe curve map and the grayscale gradient map, taking the interference fringe curve of the first area as a reference, and adopts the phase model conversion method to draw the grayscale phase curve with the grayscale value as the abscissa and the calculated phase modulation amount as the ordinate. The phase model conversion satisfies the following relationship:

[0055]

[0056] Among them, ∧ is the stripe period, is the phase modulation; δ is the fringe shift.

[0057] The test method for obtaining the phase modulation curve of the spatial light modulator of this embodiment pre-draws a grayscale gradient map, so that the spatial light modulator 6 can load the grayscale gradient map corresponding to the grayscale values ​​of 0-255 at one time. Therefore, the optical path system can output the interference fringes corresponding to each grayscale value in the grayscale values ​​of 0-255 at one time. This design can improve the processing time and processing speed on the one hand, and avoid errors introduced by the environment and operation on the other hand, thereby improving the test accuracy.

[0058] See also Figure 2 and Figure 3An embodiment of the present invention further provides a test system for obtaining a phase modulation curve of a spatial light modulator. The system for obtaining a phase modulation curve of a spatial light modulator includes an optical path system, an image processing module, and an information processing module. The information processing module is used to output a grayscale gradient map. The optical path system outputs an interference fringe image according to the grayscale value corresponding to the grayscale gradient map. The image processing module is used to clarify and edge the interference fringe image, and to extract the center line of the processed interference fringe image to generate an interference fringe curve map. The information processing module receives the interference fringe curve map output by the image processing, and outputs a grayscale phase curve according to the information of the interference fringe curve map and the grayscale gradient map.

[0059] Specifically, the grayscale gradient map includes three regions, namely the first region, the second region and the third region. The grayscale value of the first region is 0, the grayscale value of the third region is a, 0≤a≤255, and the grayscale value of the second region increases by b from the first grayscale preset value until it increases to the second grayscale preset value, where b is an integer. The grayscale value of the second region can be tested and drawn according to actual needs.

[0060] In actual testing, it is generally necessary to test the phase modulation amount corresponding to the grayscale value of 0-255. Therefore, in this embodiment, the grayscale value of the third area is 255, the first grayscale preset value of the second area is 0, the second grayscale preset value is 255, and b is 1, that is, the grayscale value of the second area gradually increases from left to right, starting from 0, until the rightmost value is 255. Figure 2 As shown, in the grayscale gradient image, the first area displays black, the second area is a gradient color area, and the third area displays white.

[0061] Optionally, the information processing module includes image processing software Matlab, and the grayscale gradient map is directly drawn by the image processing software Matlab.

[0062] When drawing a grayscale gradient image, the pixel size of the second area is calculated according to the resolution size. The resolution size is defined as M*N, the pixel size is d, the width of the first area and the third area is L1, the width of the second area is D, and the number of pixels occupied by the second area is m.

[0063]

[0064] D=md.

[0065] The implementation method of clarifying and edge processing the interference fringe image is as follows: first, using an image smoothing algorithm to eliminate noise to enhance the interference fringe image; then, using an image sharpening technique to make the edge of the interference fringe image clear.

[0066] like Figure 2 As shown, four periods of interference fringe curves are exemplarily displayed, and the interference fringe curve of the first area portion corresponding to the grayscale gradient diagram is a smooth straight line, because the grayscale value of the spatial light modulator 6 corresponding to the interference fringe curve of the first area portion is a fixed value of 0, and the interference fringe curve of the third area portion is a smooth straight line, because the grayscale value of the spatial light modulator 6 corresponding to the interference fringe curve of the third area portion is a fixed value of 255, and the grayscale value of the spatial light modulator 6 corresponding to the interference fringe curve of the second area portion is a grayscale value varying from 0 to 255, therefore, the interference fringe curve of the second area portion is a smooth oblique line.

[0067] Preferably, the optical path system includes a laser 1, a beam expander 2, a polarizer 3, a beam splitter 4, a reflector 5, a spatial light modulator 6, a lens 7 and an image acquisition device 8. The laser beam emitted by the laser 1 is expanded by the beam expander 2. The expanded laser beam passes through the polarizer 3, and its polarization direction is adjusted to be parallel to the long axis direction of the liquid crystal of the spatial light modulator. The adjusted laser beam is vertically incident on the beam splitter 4 and is divided into two mutually perpendicular first and second beams. The first beam is transmitted and vertically incident on the spatial light modulator 6. The first beam modulated by the spatial light modulator 6 is reflected by the beam splitter 4 and passes through the lens 7 to generate a structured light field as the structured light. The second beam is reflected and vertically incident on the reflector 5, and is reflected back to the beam splitter prism 4 by the reflector 5 as the reference light. The reference light and the structured light converge at the beam splitter prism 4 to interfere, and are focused and imaged on the image acquisition device 8 through the lens 7. The image acquisition device 8 outputs an interference fringe image.

[0068] Traditional test systems obtain the offset by interfering by loading different grayscale images to the spatial light modulator 6 one by one (that is, if the grayscale value changes according to 1, if you want to load grayscale values ​​of 0-255, you need to load 255 times). The operation is relatively complicated and is greatly affected by the environment. The subsequent data processing is also relatively complicated and the accuracy is not high. The spatial light modulator 6 of this embodiment can load the grayscale gradient image corresponding to the grayscale values ​​of 0-255 at one time. Therefore, the optical path system can output the interference fringes corresponding to each grayscale value in the grayscale values ​​of 0-255 at one time. This design can improve the processing time and processing speed on the one hand, and avoid the errors introduced by the environment and operation on the other hand, and improve the test accuracy.

[0069] The specific implementation method of the information processing module outputting the gray phase curve according to the information of the interference fringe curve diagram and the gray gradient diagram is as follows: taking the interference fringe curve of the first area as a reference, using the phase model conversion method to calculate the phase modulation amount corresponding to each gray value of the second area, and drawing the gray phase curve with the gray value as the abscissa and the calculated phase modulation amount as the ordinate, the phase model conversion satisfies the following relationship:

[0070]

[0071] Among them, ∧ is the stripe period, is the phase modulation; δ is the fringe shift.

[0072] The above description is only a preferred embodiment of the present invention, and does not limit the patent scope of the present invention. All equivalent structural changes made by using the contents of the present invention specification and drawings under the inventive concept of the present invention, or directly / indirectly applied in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A test method for obtaining a phase modulation curve of a spatial light modulator, characterized in that: The following steps are involved: Step S10, drawing a grayscale gradient map, the grayscale gradient map includes three regions, namely a first region, a second region and a third region, the grayscale value of the first region is 0, the grayscale value of the third region is a, 0≤a≤255, and the grayscale value of the second region increases by b from the first grayscale preset value until it increases to the second grayscale preset value, where b is an integer; Step S20, constructing an optical path system for outputting structured light and reference light, wherein a spatial light modulator of the optical path system is used to load the grayscale gradient map, and phase modulate the structured light according to the grayscale value of the grayscale gradient map, so that the phase-modulated structured light interferes with the reference light to form interference fringes; Step S30, collecting the interference fringes to generate an interference fringe image, wherein the interference fringe image includes an interference fringe image from the first grayscale preset value to the second grayscale preset value; Step S40, performing a clearing and edge processing on the interference fringe image, and extracting a center line of the interference fringe image to generate an interference fringe curve graph; Step S50, outputting a gray phase curve according to the information of the interference fringe curve graph and the gray gradient graph, wherein: In the step S10, the grayscale gradient map is drawn by using the information processing module. When drawing the grayscale gradient map, the pixel size occupied by the second area is calculated according to the resolution size. The resolution size is defined as M*N, the pixel size is d, the width of the first area and the third area is L1, the width of the second area is D, and the number of pixels occupied by the second area is m. D=md.

2. The test method for obtaining a phase modulation curve of a spatial light modulator according to claim 1, characterized in that: In step S10, the first grayscale preset value is 0, the second grayscale preset value is 255, b is 1, and the grayscale value of the third area is 255.

3. The testing method for obtaining a phase modulation curve of a spatial light modulator according to claim 1, characterized in that: The optical path system includes a laser, a beam expander, a polarizer, a beam splitter, a reflector, a spatial light modulator, a lens and an image acquisition device. The laser beam emitted by the laser is expanded by the beam expander. The expanded laser beam passes through the polarizer, and its polarization direction is adjusted to be parallel to the long axis direction of the liquid crystal of the spatial light modulator. The adjusted laser beam is vertically incident on the beam splitter prism and is divided into two mutually perpendicular first and second beams. The first beam is transmitted and vertically incident on the spatial light modulator. The first beam modulated by the spatial light modulator is reflected by the beam splitter prism and then passes through the lens to generate a structured light field as structured light. The second beam is reflected and vertically incident on the reflector, and is reflected by the reflector back to the beam splitter prism as reference light. The reference light and the structured light converge at the beam splitter prism to interfere, and are focused and imaged on the image acquisition device through the lens. The image acquisition device outputs an interference fringe image.

4. The testing method for obtaining a phase modulation curve of a spatial light modulator according to claim 1, wherein: In step S40, the implementation method of the clarification and edge processing of the interference fringe image is: using an image smoothing algorithm to eliminate noise to enhance the interference fringe image; using image sharpening technology to make the edge of the interference fringe image clear.

5. The testing method for obtaining a phase modulation curve of a spatial light modulator according to claim 1, wherein: In step S50, the specific implementation method of outputting the gray phase curve according to the information of the interference fringe curve graph and the gray gradient graph is: The interference fringe curve and the grayscale gradient map are input into an information processing module. The information processing module uses the interference fringe curve of the first area as a reference, calculates the phase modulation amount corresponding to each grayscale value of the second area by using a phase model conversion method, and draws a grayscale phase curve with the grayscale value as the abscissa and the calculated phase modulation amount as the ordinate. The phase model conversion satisfies the following relationship: Among them, ∧ is the stripe period, is the phase modulation; δ is the fringe shift.

6. A test system for obtaining a phase modulation curve of a spatial light modulator, using the test method of claim 1, characterized in that: The system for obtaining the phase modulation curve of a spatial light modulator includes an optical path system, an image processing module and an information processing module. The information processing module is used to output a grayscale gradient map. The optical path system outputs an interference fringe image according to the grayscale value corresponding to the grayscale gradient map. The image processing module is used to clarify and edge the interference fringe image, and to extract the center line of the processed interference fringe image to generate an interference fringe curve map. The information processing module receives the interference fringe curve map output by the image processing, and outputs a grayscale phase curve according to the information of the interference fringe curve map and the grayscale gradient map.

7. The test system for obtaining a phase modulation curve of a spatial light modulator according to claim 6, characterized in that: The grayscale gradient map includes three areas, namely the first area, the second area and the third area. The grayscale value of the first area is 0, the grayscale value of the third area is a, 0≤a≤255, and the grayscale value of the second area increases by b from the first grayscale preset value until it increases to the second grayscale preset value, where b is an integer.

8. The test system for obtaining a phase modulation curve of a spatial light modulator according to claim 7, characterized in that: The first grayscale preset value is 0, the second grayscale preset value is 255, b is 1, and the grayscale value of the third area is 255.

9. The test system for obtaining a phase modulation curve of a spatial light modulator according to claim 8, characterized in that: The optical path system includes a laser, a beam expander, a polarizer, a beam splitter, a reflector, a spatial light modulator, a lens and an image acquisition device. The laser beam emitted by the laser is expanded by the beam expander. The expanded laser beam passes through the polarizer, and its polarization direction is adjusted to be parallel to the long axis direction of the liquid crystal of the spatial light modulator. The adjusted laser beam is vertically incident on the beam splitter prism and is divided into two mutually perpendicular first and second beams. The first beam is transmitted and vertically incident on the spatial light modulator. The first beam modulated by the spatial light modulator is reflected by the beam splitter prism and then passes through the lens to generate a structured light field as structured light. The second beam is reflected and vertically incident on the reflector, and is reflected by the reflector back to the beam splitter prism as reference light. The reference light and the structured light converge at the beam splitter prism to interfere, and are focused and imaged on the image acquisition device through the lens. The image acquisition device outputs an interference fringe image.

Images