Diffraction Efficiency Measurement Device for LCoS Chip

Abstract

The present application provides a diffraction efficiency measurement device for an LCoS chip, which relates to the field of optical communication technologies. The device includes: a diffraction optical path module, a detection module, and a processing module; the diffraction optical path module is configured to reflect an input light source signal to a target LCoS chip according to a preset diffraction optical path, and the blazed gratings with different periods displayed on the target LCoS chip diffract the received light source signal to generate diffracted light corresponding to the blazed gratings with different periods; the detection module is configured to measure the optical signal intensity of the diffracted light corresponding to the blazed gratings with different periods, and send the optical signal intensity of the diffracted light corresponding to the blazed gratings with different periods to the processing module; the processing module is further configured to determine the diffraction efficiency of the target LCoS chip according to the optical signal intensity of the diffracted light corresponding to the blazed gratings with different periods, realizing the measurement of the optical signal intensity of the diffracted light corresponding to the blazed gratings with different periods displayed by the target LCoS chip at the same angle, and increasing the reliability of the test.

Description

Technical Field

[0001] The present invention relates to the field of optical communication technologies, and in particular, to a device for measuring the diffraction efficiency of an LCoS chip. Background Art

[0002] A liquid crystal on silicon (LCoS) device is an optical device based on reflective liquid crystal display technology and is widely used in fields such as projection display, spatial light modulator (SLM), and optical communication. Among them, the diffraction efficiency is one of the key indicators for evaluating the optical performance of an LCoS device, which represents the ratio of the light intensity effectively diffracted in a specified direction after the incident light passes through the LCoS device to the total intensity of the incident light. The higher the diffraction efficiency, the more light is effectively utilized, and the higher the imaging brightness and the overall efficiency of the optical system.

[0003] In related technologies, the diffraction efficiency is measured by loading a blazed grating on an LCoS chip and measuring the power of the diffracted light diffracted by the blazed grating. However, since blazed gratings with different periods correspond to different diffraction angles, during measurement, it is necessary to continuously change / adjust the position of the detector, or use it in combination with an expensive fiber optic coupling collimator array. The diffraction angle is difficult to control, and the integer grating period also results in an obvious discrete distribution of the diffraction angles, thus unable to comprehensively reflect the performance of the LCoS device. Summary of the Invention

[0004] The purpose of the present invention is to provide a device for measuring the diffraction efficiency of an LCoS chip to solve the technical problems existing in the prior art in view of the deficiencies in the above-mentioned prior art.

[0005] To achieve the above purpose, the technical solutions adopted in the embodiments of the present application are as follows:

[0006] In a first aspect, the embodiments of the present application provide a device for measuring the diffraction efficiency of an LCoS chip, and the device includes: a diffraction optical path module, a detection module, and a processing module;

[0007] The output end of the detection module is connected to the input end of the processing module, and the output end of the processing module is connected to the control end of the target LCoS chip to be measured in the diffraction optical path module;

[0008] The processing module is configured to control the target LCoS chip to display blazed gratings with different periods;

[0009] The diffraction optical path module is configured to reflect the input light source signal to the target LCoS chip according to a preset diffraction optical path, and the blazed gratings with different periods displayed on the target LCoS chip diffract the received light source signal to generate diffracted light corresponding to the blazed gratings with different periods;

[0010] The detection module is configured to measure the optical signal intensity of the diffracted light corresponding to each period of the blazed grating, and send the optical signal intensity of the diffracted light corresponding to each period of the blazed grating to the processing module;

[0011] The processing module is further configured to determine the diffraction efficiency of the target LCoS chip according to the optical signal intensity of the diffracted light corresponding to each period of the blazed grating.

[0012] Optionally, the diffraction optical path module includes: an annular unit, a collimating unit, a polarization unit and a mounting base;

[0013] The mounting base is used to fixedly mount the target LCoS chip;

[0014] The annular unit is configured to reflect the input light source signal to the collimating unit according to a preset first specified path;

[0015] The collimating unit is configured to collimate the light beam emitted by the annular unit into a parallel light beam, and send the parallel light beam to the polarization unit;

[0016] The polarization unit is configured to convert the parallel light beam into a linearly polarized light beam, and emit the linearly polarized light beam to the target LCoS chip. The blazed gratings with different periods displayed on the target LCoS chip diffract the linearly polarized light beam to generate diffracted light corresponding to the blazed gratings with different periods, and reflect the diffracted light corresponding to the blazed gratings with different periods to the annular unit;

[0017] The annular unit is further configured to reflect the diffracted light corresponding to the blazed gratings with different periods to the detection module according to a preset second specified path.

[0018] Optionally, the annular unit includes: a three-port optical circulator, and the three-port optical circulator includes: a first port, a second port and a third port;

[0019] The first specified path is used to indicate the transmission path from the first port to the second port; the second specified path is used to indicate the transmission path from the second port to the third port.

[0020] Optionally, the detection module includes: a light intensity sensor.

[0021] Optionally, the control target LCoS chip displays blazed gratings of different periods, including:

[0022] Obtain the relationship between wavelength and blaze angle in the pre-constructed blazed grating;

[0023] According to the relationship between wavelength and blaze angle in the blazed grating, determine the minimum phase change amount, variable coefficients corresponding to different diffraction orders, and diffraction angles; wherein, the product of the phase change amount and the variable coefficients corresponding to different diffraction orders is the phase difference between adjacent pixels;

[0024] According to the variable coefficients corresponding to different diffraction orders, determine the blazed gratings of each period corresponding to the diffraction angle;

[0025] When the polarization angle of the collimation unit in the diffraction efficiency measurement device with respect to the target LCoS chip is the diffraction angle, send the blazed gratings of each period to the target LCoS chip, and control the target LCoS chip to display the blazed gratings of each period.

[0026] Optionally, the determining the blazed gratings of each period corresponding to the diffraction angle according to the variable coefficients corresponding to different diffraction orders includes:

[0027] Obtain the expression of the phase value corresponding to each row of pixels in the pre-constructed blazed grating;

[0028] Respectively input the variable coefficients corresponding to each diffraction order into the expression to obtain the phase diagrams of the blazed gratings of each period;

[0029] According to the gray scale-phase relationship of the pre-constructed target LCoS chip and the phase diagrams of the blazed gratings of each period, obtain the gray scale diagrams of the blazed gratings of each period.

[0030] Optionally, the determining the diffraction efficiency of the target LCoS chip according to the optical signal intensity of the diffracted light corresponding to the blazed gratings of each period includes:

[0031] Obtain the initial optical signal intensity of the target LCoS chip;

[0032] Respectively determine the ratios of the optical signal intensities of the diffracted lights corresponding to the blazed gratings of each period to the initial optical signal intensity;

[0033] According to the ratios of the optical signal intensities of the diffracted lights corresponding to the blazed gratings of each period to the initial optical signal intensity, determine the diffraction efficiency of the target LCoS chip.

[0034] Optionally, the obtaining the initial optical signal intensity of the target LCoS chip includes:

[0035] When the polarization angle of the collimation unit in the diffraction efficiency measurement device with respect to the target LCoS chip is zero, control the target LCoS chip to display a first grayscale test image, and the grayscale value of the first grayscale test image is 0;

[0036] Control the target LCoS chip to display a plurality of second test grayscale maps, and the grayscale of the second test grayscale map is a target value, and the target value is any value in the range of 0-255;

[0037] Obtain the optical signal intensity corresponding to each of the second test grayscale maps detected by the detection module, and determine the initial optical signal intensity of the target LCoS chip according to the optical signal intensity corresponding to each of the second test grayscale maps.

[0038] Optionally, the determining the initial optical signal intensity of the target LCoS chip according to the optical signal intensity corresponding to each of the second test grayscale maps includes:

[0039] Determine the mean value of the optical signal intensity corresponding to each of the second test grayscale maps, and use the mean value as the initial optical signal intensity of the target LCoS chip.

[0040] The beneficial effects of this application are:

[0041] The present application provides a diffraction efficiency measurement device for an LCoS chip. The device includes a diffraction optical path module, a detection module, and a processing module. The output end of the detection module is connected to the input end of the processing module, and the output end of the processing module is connected to the control end of the target LCoS chip to be measured in the diffraction optical path module. The processing module is configured to control the target LCoS chip to display blazed gratings with different periods. The diffraction optical path module is configured to reflect the input light source signal to the target LCoS chip according to a preset diffraction optical path, and the blazed gratings with different periods displayed on the target LCoS chip diffract the received light source signal to generate diffracted light corresponding to the blazed gratings with different periods. The detection module is configured to measure the optical signal intensity of the diffracted light corresponding to each period of the blazed grating and send the optical signal intensity of the diffracted light corresponding to each period of the blazed grating to the processing module. The processing module is further configured to determine the diffraction efficiency of the target LCoS chip according to the optical signal intensity of the diffracted light corresponding to each period of the blazed grating. In this solution, the processing module controls the target LCoS chip to display blazed gratings with integer periods and non-integer periods, that is, compared with the related art, the blazed gratings with non-integer periods are added, which solves the problem in the related art that only the blazed gratings with integer periods are used, resulting in an obvious discrete distribution of the diffraction angle and unable to comprehensively reflect the performance of the LCOS device, and greatly improves the measurement accuracy of the diffraction angle. Then, the diffraction optical path module reflects the input light source signal to the target LCoS chip, and the blazed gratings with different periods displayed on the target LCoS chip diffract the received light source signal to generate diffracted light corresponding to the blazed gratings with different periods, that is, the target LCoS chip is installed at a fixed position in the diffraction optical path module, and the diffraction angle of the generated diffracted light is fixed, realizing the measurement of the optical signal intensity of the diffracted light corresponding to the blazed gratings with different periods displayed by the target LCoS chip at the same angle without changing the position of the detection module, which greatly increases the reliability of the test. At the same time, the processing module determines the diffraction efficiency of the target LCoS chip at different diffraction orders according to the optical signal intensity of the diffracted light corresponding to the blazed gratings with different periods, which greatly increases the reliability of the test and solves the problem in the related art that due to different diffraction angles corresponding to the blazed gratings with different periods, the position of the detector needs to be continuously changed / adjusted during measurement, resulting in a low measurement efficiency. Description of the Drawings

[0042] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for the embodiments. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as limiting the scope. For those of ordinary skill in the art, other related drawings can be obtained based on these drawings without creative efforts.

[0043] Figure 1 Schematic structural diagram of a diffraction efficiency measurement device for an LCoS chip provided by an embodiment of the present application;

[0044] Figure 2 Schematic structural diagram of a diffraction optical path module provided by an embodiment of the present application;

[0045] Figure 3 Schematic diagram of the processing flow of a processing unit provided by an embodiment of the present application Figure 1 ;

[0046] Figure 4 Schematic diagram of the diffraction principle of an LCoS chip provided by an embodiment of the present application;

[0047] Figure 5 Schematic diagram of the processing flow of a processing unit provided by an embodiment of the present application Figure 2 ;

[0048] Figure 6 Schematic diagram of the gray scale-phase relationship formula of an LCoS chip provided by an embodiment of the present application;

[0049] Figure 7 Schematic diagram of a blazed grating when m = 0.001π and n = 120 provided by an embodiment of the present application;

[0050] Figure 8 Schematic diagram of a blazed grating when m = 0.001π and n = 60 provided by an embodiment of the present application;

[0051] Figure 9 Schematic diagram of a blazed grating when m = 0.001π and n = 40 provided by an embodiment of the present application;

[0052] Figure 10 Schematic diagram of the processing flow of a processing unit provided by an embodiment of the present application Figure 3 ;

[0053] Figure 11 Schematic diagram of the processing flow of a processing unit provided by an embodiment of the present application Figure 4 。

[0054] Icons: 100 - Diffraction efficiency measurement device; 1 - Diffraction optical path module; 2 - Detection module; 3 - Processing module; 11 - Ring unit, 12 - Collimation unit; 13 - Polarization unit; 14 - Mounting base. Detailed implementation manners

[0055] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of this application. It should be understood that the accompanying drawings in this application are only for the purposes of illustration and description, and are not used to limit the protection scope of this application. Additionally, it should be understood that the schematic drawings are not drawn to scale. The flowcharts used in this application illustrate the operations implemented according to some embodiments of this application. It should be understood that the operations in the flowchart may not be implemented in sequence, and steps without a logical context relationship may be reversed or implemented simultaneously. In addition, those skilled in the art can add one or more other operations to the flowchart or remove one or more operations from the flowchart under the guidance of the content of this application.

[0056] In addition, the described embodiments are only some embodiments of this application, rather than all embodiments. The components of the embodiments of this application usually described and illustrated in the accompanying drawings here can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of this application that is claimed, but merely represents the selected embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative efforts fall within the scope of protection of this application.

[0057] It should be noted that the term "including" will be used in the embodiments of this application to indicate the existence of the features stated thereafter, but does not exclude the addition of other features.

[0058] The structure of the diffraction efficiency measurement device for the LCoS chip of this application will be described in detail below through multiple embodiments.

[0059] Figure 1 It is a schematic structural diagram of a diffraction efficiency measurement device for an LCoS chip provided in the embodiments of this application; as Figure 1 shown, the device includes: a diffraction optical path module 1, a detection module 2, and a processing module 3.

[0060] Among them, the diffraction optical path module 1 can be composed of multiple optical elements, that is, it can achieve the diffraction of the light source signal.

[0061] Exemplarily, the detection module 2 can be a photodiode, and the detection module 2 can capture the optical signal intensity of the diffracted light reflected by the diffraction optical path module 1.

[0062] The output end of the detection module 2 is connected to the input end of the processing module 3, and the output end of the processing module 3 is connected to the control end of the target LCoS chip to be measured in the diffraction optical path module 1.

[0063] The processing module 3 is used to control the target LCoS chip to display blazed gratings with different periods; among them, the optical signal intensities of the diffracted lights corresponding to the blazed gratings with different periods are different. The different periods include: integer periods and non-integer periods, that is, non-integer period blazed gratings are added, which solves the problem in the related technology that only integer period blazed gratings are used, resulting in an obvious discrete distribution of diffraction angles and unable to comprehensively reflect the performance of the LCOS device, and greatly improves the measurement accuracy of the diffraction angle.

[0064] The diffraction optical path module 1 is used to reflect the input light source signal to the target LCoS chip according to a preset diffraction optical path, and the blazed gratings with different periods displayed on the target LCoS chip diffract the received light source signal to generate diffracted lights corresponding to the blazed gratings with different periods; that is, the target LCoS chip is installed at a fixed position in the diffraction optical path module, and the diffraction angle of the generated diffracted light is fixed, so that the optical signal intensities of the diffracted lights corresponding to the blazed gratings with different periods displayed by the target LCoS chip can be measured at the same angle, without changing the position of the detection module, greatly increasing the reliability of the test.

[0065] The detection module 2 is used to measure the optical signal intensities of the diffracted lights corresponding to the blazed gratings of each period and send the optical signal intensities of the diffracted lights corresponding to the blazed gratings of each period to the processing module; among them, the optical signal intensity of the diffracted light reflects the diffraction efficiency of the current period blazed grating on the light source signal.

[0066] The processing module 3 is further used to determine the diffraction efficiency of the target LCoS chip according to the optical signal intensities of the diffracted lights corresponding to the blazed gratings of each period.

[0067] Among them, when the incident light irradiates the surface of the blazed grating, multiple diffraction orders will be generated in different directions, and the angle and intensity of each diffraction order depend on the period of the blazed grating, the groove shape, and the wavelength and incident angle of the incident light.

[0068] Therefore, in this application, the diffraction angle, the groove shape, and the wavelength and incident angle of the incident light are all set to fixed values, that is, the intensity of the same diffraction order depends on the period of the blazed grating. That is, when the diffraction angle is fixed, the diffraction efficiency of the target LCoS chip at different diffraction orders can be determined according to the optical signal intensities of the diffracted lights corresponding to the blazed gratings with different periods, greatly increasing the reliability of the test, and solving the problem in the related technology that due to different diffraction angles corresponding to different period blazed gratings, the position of the detector needs to be continuously changed / adjusted during measurement, resulting in a low measurement efficiency.

[0069] Meanwhile, in the present application, only the diffraction optical path module is required to generate the diffracted light corresponding to the blazed gratings with different periods. It is not necessary to use an expensive fiber-coupled collimator array, and the diffraction angle can be accurately controlled, ensuring the accuracy of the measurement results.

[0070] In summary, the present application provides a device for measuring the diffraction efficiency of an LCoS chip. The device includes: a diffraction optical path module, a detection module, and a processing module; the output end of the detection module is connected to the input end of the processing module, and the output end of the processing module is connected to the control end of the target LCoS chip to be measured in the diffraction optical path module; the processing module is configured to control the target LCoS chip to display blazed gratings with different periods; the diffraction optical path module is configured to reflect the input light source signal to the target LCoS chip according to a preset diffraction optical path, and the blazed gratings with different periods displayed on the target LCoS chip diffract the received light source signal to generate diffracted light corresponding to the blazed gratings with different periods; the detection module is configured to measure the optical signal intensity of the diffracted light corresponding to each period of the blazed grating and send the optical signal intensity of the diffracted light corresponding to each period of the blazed grating to the processing module; the processing module is further configured to determine the diffraction efficiency of the target LCoS chip according to the optical signal intensity of the diffracted light corresponding to each period of the blazed grating. In this solution, the processing module controls the target LCoS chip to display blazed gratings with integer periods and non-integer periods, that is, compared with the related art, the blazed gratings with non-integer periods are added, which solves the problem in the related art that only the blazed gratings with integer periods are used, resulting in an obvious discrete distribution of the diffraction angle and unable to comprehensively reflect the performance of the LCOS device, and greatly improves the measurement accuracy of the diffraction angle; then, the diffraction optical path module reflects the input light source signal to the target LCoS chip, and the blazed gratings with different periods displayed on the target LCoS chip diffract the received light source signal to generate diffracted light corresponding to the blazed gratings with different periods, that is, the target LCoS chip is installed at a fixed position in the diffraction optical path module, and the diffraction angle of the generated diffracted light is fixed, realizing the measurement of the optical signal intensity of the diffracted light corresponding to the blazed gratings with different periods displayed by the target LCoS chip at the same angle without changing the position of the detection module, greatly increasing the reliability of the test; at the same time, the processing module determines the diffraction efficiency of the target LCoS chip at different diffraction orders according to the optical signal intensity of the diffracted light corresponding to the blazed gratings with different periods, greatly increasing the reliability of the test, and solving the problem in the related art that due to different diffraction angles corresponding to the blazed gratings with different periods, the position of the detector needs to be continuously changed / adjusted during measurement, resulting in a low measurement efficiency.

[0071] Optionally, refer to Figure 2As shown in the figure, the diffractive optical path module 1 includes: an annular unit 11, a collimating unit 12, a polarization unit 13, and a mounting base 14.

[0072] The mounting base 14 is used to fixedly install the target LCoS chip; that is, the target LCoS chip can be installed on the mounting base 14. Among them, the pixel size of the target LCoS chip is d, which is used to load blazed gratings with different periods and reflect the light from one port in the annular unit 11.

[0073] The annular unit 11 is used to reflect the input light source signal to the collimating unit according to a preset first specified path; among them, the light source signal is in the visible light band and can also be extended to the infrared band.

[0074] The annular unit 11 utilizes the nonlinear optical effect to achieve the directional transmission of optical signals through the magneto-optical effect (such as the Faraday effect) or the electro-optical effect. Therefore, the input light source signal can be reflected to the collimating unit along the first specified path by the annular unit 11, and the light source signal will not be lost during the transmission process.

[0075] The collimating unit 12 is used to collimate the light beam emitted by the annular unit into a parallel light beam and send the parallel light beam to the polarization unit; exemplarily, the collimating unit 12 can be a collimator, that is, the light beam emitted by the annular unit 11 can be collimated into a parallel light beam by the collimating unit 12, reducing the divergence angle of the light beam, improving the coupling efficiency between the optical fiber and other components, and reducing optical losses. At the same time, the collimating unit 12 forms an angle γ with the vertical direction of the target LCoS chip, which is used to ensure that the reflected light of the target LCoS chip can return along the original path.

[0076] The polarization unit 13 is used to convert the parallel light beam into a linearly polarized light beam and emit the linearly polarized light beam to the target LCoS chip. The blazed gratings with different periods displayed on the target LCoS chip diffract the linearly polarized light beam to generate diffracted light corresponding to the blazed gratings with different periods, and reflect the diffracted light corresponding to the blazed gratings with different periods to the annular unit. Among them, the polarization unit 13 is used to convert the incident light into a linearly polarized light beam, and its polarization direction is parallel to the orientation direction of the LCoS chip; therefore, the parallel light beam can be converted into a linearly polarized light beam by the polarization unit 13 and the linearly polarized light beam is emitted to the target LCoS chip. The blazed gratings with different periods displayed on the target LCoS chip diffract the linearly polarized light beam to generate diffracted light corresponding to the blazed gratings with different periods, and reflect the diffracted light corresponding to the blazed gratings with different periods to the annular unit 11.

[0077] The annular unit 11 is also configured to reflect the diffracted light corresponding to the blazed gratings of different periods to the detection module according to a preset second specified path. Specifically, the annular unit 11 can reflect the diffracted light corresponding to the blazed gratings of different periods to the detection module 2 along the second specified path. The first specified path is different from the second specified path, so as to guide the diffracted light corresponding to the blazed gratings of different periods to the detection module through the second specified path, and the detection module detects the optical signal intensity of the diffracted light corresponding to the blazed gratings of different periods.

[0078] Optionally, continue to refer to Figure 2 As shown, the annular unit includes: a three-port optical circulator, and the three-port optical circulator includes: a first port Port1, a second port Port2, and a third port Port3.

[0079] The first specified path is used to indicate the transmission path from the first port Port1 to the second port Port2; the second specified path is used to indicate the transmission path from the second port Port2 to the third port Port3.

[0080] In this embodiment, after the light source signal enters from the first port Port1 in the annular unit, it is sequentially guided to the second port Port2, and then from the second port Port2 to the third port Port3, and the third port Port3 does not directly affect the light source signal entering from the first port Port1.

[0081] Optionally, the detection module includes: a light intensity sensor. Exemplarily, the light intensity sensor can include: a photodiode or a photoelectric diode, etc.

[0082] Optionally, in the present application, by building the above-mentioned Figure 2 shown diffractive optical path module and adopting the oblique incidence method, there is no need to purchase an additional fiber optic coupling collimator array, which greatly saves the test cost.

[0083] The following embodiments will specifically explain how the processing unit controls the target LCoS chip to display blazed gratings of different periods.

[0084] Optionally, refer to Figure 3 As shown, it is a schematic diagram of the processing flow of the processing unit, and the process includes:

[0085] S301. Obtain the relationship between the wavelength and the blaze angle in the pre-constructed blazed grating.

[0086] Optionally, refer to Figure 4 As shown, it is a schematic diagram of the diffraction principle of the LCoS chip. As Figure 4 shown, let the angle between the virtual grating plane of the blazed grating and the pixel electrode plane of the LCoS chip be α, which is the blaze angle, the incident angle be β, and the diffraction angle be θ.

[0087] The pixel electrode width of the LCoS chip is d. When the 0-2Pi phase is evenly divided into N layers of steps (i.e., N columns / rows of pixels), the height of each layer of steps is Δφ (Δφ = 2Pi / N), and the blazed grating period is P (P = N*d).

[0088] According to the blazed grating theory, the relationship between the wavelength and the blazed angle is given by the following formula (1):

[0089] 2P*sinα*cos(β - α) = k*λ (1)

[0090] Where k is the diffraction order (usually k is ±1, ±2, ±3), and λ is the wavelength. Substituting β = θ = α into the above formula (1) gives the following formulas (2)-(3):

[0091] 2P*sinθ = k*λ (2)

[0092] 2N*d*sinθ = k*λ (3)

[0093] From the above formula (3), it can be seen that when the diffraction angle θ is fixed, to measure the optical signal intensity of the k-th order diffracted light, it can be achieved by changing the period of the blazed grating (N*d). Therefore, from the binary blazed grating, it can be known that the phase difference between adjacent pixels, that is, the maximum height of the steps is π.

[0094] S302. Determine the minimum phase change amount, the variable coefficient corresponding to different diffraction orders, and the diffraction angle according to the relationship between the wavelength and the blazed angle in the blazed grating.

[0095] Where the product of the phase change amount and the variable coefficient corresponding to different diffraction orders is the phase difference between adjacent pixels.

[0096] Optionally, the period of the blazed grating (N*d) can also be expressed as N*d = 2d*π / n / m. Substituting N*d = 2d*π / n / m into the above formula (3), the following formula (4) can be obtained:

[0097] 4π*d*sinθ / n / m = k*λ (4)

[0098] Where n*m is the phase difference between adjacent pixels, m is the minimum phase change amount, and n is the variable coefficient corresponding to different diffraction orders. Therefore, the value range of the variable coefficient n corresponding to different diffraction orders can also be determined as [-π / m π / m], n is an integer, and the "-" represents a decreasing phase.

[0099] S303. Determine the blazed gratings of each period corresponding to the diffraction angle according to the variable coefficients corresponding to different diffraction orders.

[0100] In an implementable manner, as shown in the above formula (4), when the pixel electrode width d, the minimum phase change amount m, the diffraction angle θ, and the wavelength λ in formula (4) are all fixed values, by adjusting the value of the variable coefficient n corresponding to different diffraction orders, a blazed grating with integer periods and non-integer periods can be obtained, greatly improving the measurement accuracy of the diffraction angle.

[0101] S304. When the polarization angle of the collimation unit in the diffraction efficiency measurement device with respect to the target LCoS chip is the diffraction angle, send the blazed gratings of each period to the target LCoS chip, and control the target LCoS chip to display the blazed gratings of each period.

[0102] Optionally, when the polarization angle of the collimation unit in the diffraction efficiency measurement device with respect to the target LCoS chip is adjusted to the diffraction angle θ, send the blazed gratings of each period to the target LCoS chip, and control the target LCoS chip to display the blazed gratings of different periods, so as to enable the measurement of the optical signal intensity of diffracted light of different orders at the same angle, and can also achieve high-precision measurement of the diffraction angle, with low test optical path cost and high test efficiency.

[0103] Optionally, referring to Figure 5 As shown, the above step S303 includes:

[0104] S501. Obtain the expression of the phase value corresponding to each row of pixels in the pre-constructed blazed grating.

[0105] In an implementable manner, for a longitudinal blazed grating, the phase corresponding to each column of pixels is consistent, the phase values corresponding to each row of pixels are periodic, and the phase value corresponding to each row of pixels can be expressed as shown in the following formula (5):

[0106] Φ (i)=mod(n / (π / m)*(i - 1)+R, 2)*π (5)

[0107] Wherein, R represents the direction constant of the blazed grating. When n is greater than or equal to 0, R = 0; when n is less than 0, R = m / π. The mod function is a remainder function, and its format is: mod(nExp1, nExp2), that is, the remainder after two numerical expressions are divided.

[0108] Φ is a periodic function, and its period is T = N = 2*π / n / m.

[0109] S502. Input the variable coefficients corresponding to each diffraction order into the expression respectively to obtain the phase diagrams of the blazed gratings of each period.

[0110] In this embodiment, the variable coefficient n1 corresponding to k = 1 can be input into the above formula (5) respectively to obtain the phase diagram of the blazed grating in the first period, where the first period T1 can be expressed as 2*π / n1 / m; and so on, the phase diagrams of the blazed gratings in other periods can also be obtained.

[0111] S503. According to the gray scale-phase relationship formula of the target LCoS chip constructed in advance and the phase diagrams of the blazed gratings in each period, obtain the gray scale diagrams of the blazed gratings in each period.

[0112] Optionally, referring to Figure 6 as shown, it is the gray scale-phase relationship formula of the LCoS chip. Therefore, the phase values corresponding to each row of pixels in the phase diagrams of the blazed gratings in each period can be substituted into the gray scale-phase relationship formula to calculate the gray scale values corresponding to each row of pixels in the blazed gratings in each period. Then, based on the gray scale values corresponding to each row of pixels in the blazed gratings in each period, the gray scale diagrams of the blazed gratings in each period are obtained.

[0113] Optionally, referring to Figures 7 - 9 as shown, they are the blazed gratings corresponding to different variable coefficients n. For example, Figure 7 as shown is the blazed grating when m = 0.001π and n = 120, Figure 8 as shown is the blazed grating when m = 0.001π and n = 60, Figure 9 as shown is the blazed grating when m = 0.001π and n = 40.

[0114] Optionally, referring to Figure 10 as shown, determine the diffraction efficiency of the target LCoS chip according to the optical signal intensity of the diffracted light corresponding to the blazed gratings in each period, including:

[0115] S1001. Obtain the initial optical signal intensity of the target LCoS chip.

[0116] S1002. Determine the ratios of the optical signal intensities of the diffracted lights corresponding to the blazed gratings in each period to the initial optical signal intensity respectively.

[0117] S1003. Determine the diffraction efficiency of the target LCoS chip according to the ratios of the optical signal intensities of the diffracted lights corresponding to the blazed gratings in each period to the initial optical signal intensity.

[0118] In an achievable manner, the initial optical signal intensity P0 of the target LCoS chip can be obtained, and the ratio of the optical signal intensity of the diffracted light corresponding to the blazed grating in each period to the initial optical signal intensity can be determined respectively. As shown in reference formula (4), when the pixel electrode width d, the minimum phase change amount m, the diffraction angle θ, and the wavelength λ are all set to fixed values, the variable coefficient n1 corresponding to the diffraction order k1 being 1 can be determined, that is, the period of the blazed grating is T1 = N = 2*π / n1 / m, and the optical signal intensity of the diffracted light corresponding to the blazed grating with period T1 is denoted as P1. Then, the ratio P1 / P0 of the optical signal intensity of the diffracted light corresponding to the blazed grating with period T1 to the initial optical signal intensity can be determined, and P1 / P0 is called the first-order diffraction efficiency η1 of the target LCoS chip.

[0119] Similarly, the variable coefficient n2 corresponding to the diffraction order k2 being 2 can also be obtained, that is, the period of the blazed grating is T2 = N = 2*π / n2 / m, and the optical signal intensity of the diffracted light corresponding to the blazed grating with period T2 is denoted as P1. Then, the ratio P2 / P0 of the optical signal intensity of the diffracted light corresponding to the blazed grating with period T2 to the initial optical signal intensity can be determined, and P2 / P0 is called the second-order diffraction efficiency η2 of the target LCoS chip.

[0120] Moreover, the variable coefficient n3 corresponding to the diffraction order k3 being 3 can also be obtained, that is, the period of the blazed grating is T3 = N = 2*π / n3 / m, and the optical signal intensity of the diffracted light corresponding to the blazed grating with period T3 is denoted as P3. Then, the ratio P3 / P0 of the optical signal intensity of the diffracted light corresponding to the blazed grating with period T3 to the initial optical signal intensity can be determined, and P3 / P0 is called the third-order diffraction efficiency η3 of the target LCoS chip.

[0121] Optionally, in this application, the diffraction efficiencies of each order at a fixed diffraction angle can be calculated, that is: η1 = P1 / P0 * 100%; η2 = P2 / P0 * 100%; η3 = P3 / P0 * 100%. It realizes the measurement of the diffracted light intensities of different orders at the same angle without changing the position of the detector, greatly increasing the reliability of the test.

[0122] Optionally, as shown in Figure 11 the above step S1001 includes:

[0123] S1101. When the polarization angle of the collimation unit in the diffraction efficiency measurement device with respect to the target LCoS chip is zero, control the target LCoS chip to display the first grayscale test image.

[0124] Among them, the grayscale value of the first grayscale test image is 0.

[0125] S1102. Control the target LCoS chip to display multiple second test grayscale images.

[0126] Among them, the gray level of the second test gray level image reaches the target value, and the target value is any value in the range of 0 - 255.

[0127] S1103. Obtain the optical signal intensity corresponding to each second test gray level image detected by the detection module, and determine the initial optical signal intensity of the target LCoS chip according to the optical signal intensity corresponding to each second test gray level image.

[0128] In a feasible manner, first power on the target LCoS chip. When the polarization angle γ of the collimation unit in the diffraction efficiency measurement device relative to the target LCoS chip is zero, make the detected optical signal intensity of the detection module maximum. At this time, the ideal state should be 0°, and control the target LCoS chip to display the first gray level test image with a pure gray level of 0; then, control the target LCoS chip to switch and display multiple second test gray level images, and the gray level value of each second test gray level image is any value in the range of 0 - 255, and respectively obtain the optical signal intensity corresponding to each second test gray level image detected by the detection module, and determine the initial optical signal intensity P0 of the target LCoS chip according to the optical signal intensity corresponding to each second test gray level image.

[0129] Optionally, determining the initial optical signal intensity of the target LCoS chip according to the optical signal intensity corresponding to each second test gray level image includes:

[0130] Determine the mean value of the optical signal intensity corresponding to each second test gray level image, and use the mean value as the initial optical signal intensity of the target LCoS chip.

[0131] In a feasible manner, the mean value of the optical signal intensity corresponding to each second test gray level image can be directly used as the initial optical signal intensity P0 of the target LCoS chip.

[0132] Optionally, the present application proposes a new diffraction efficiency measurement device for LCoS chips, which can measure the diffraction light intensities of different orders at the same angle, and can also realize continuous measurement of the diffraction angle. The test optical path has low cost and high test efficiency, and solves the problem that in the related technology, using a blazed grating with an integer period results in an obvious discrete distribution of the diffraction angle, so that the performance of the LCoS device cannot be comprehensively reflected.

[0133] Optionally, the present invention further provides a program product, such as a computer-readable storage medium, including a program, which is used to execute the above method embodiments when executed by a processor.

[0134] In several embodiments provided by the present invention, it should be understood that the disclosed devices and methods can be implemented in other ways. For example, the device embodiments described above are merely illustrative. For example, the division of the units is only a logical function division. In actual implementation, there may be other division methods. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the displayed or discussed couplings or direct couplings or communication connections to each other can be through some interfaces. The indirect couplings or communication connections of the devices or units can be in electrical, mechanical or other forms.

[0135] The units described as separate components may or may not be physically separated. The components displayed as units may or may not be physical units, that is, they can be located in one place or distributed to multiple network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0136] In addition, in each embodiment of the present invention, the functional units can be integrated in a processing unit, or each unit can exist physically alone, or two or more units can be integrated in one unit. The above integrated units can be implemented in the form of hardware or in the form of hardware plus software functional units.

[0137] The above integrated units implemented in the form of software functional units can be stored in a computer-readable storage medium. The above software functional units stored in a storage medium include several instructions for causing a computer device (which can be a personal computer, a server, or a network device, etc.) or a processor (English: processor) to execute some steps of the methods described in each embodiment of the present invention. The aforementioned storage medium includes: USB flash drives, mobile hard disks, read-only memories (English: Read-Only Memory, abbreviated as: ROM), random access memories (English: Random Access Memory, abbreviated as: RAM), magnetic disks or optical disks and other various media that can store program codes.

Claims

1. A device for measuring the diffraction efficiency of an LCoS chip, characterized in that: The device comprises: a diffraction optical path module, a detection module and a processing module; The output end of the detection module is connected to the input end of the processing module, and the output end of the processing module is connected to the control end of the target LCoS chip to be tested in the diffraction optical path module; The processing module is used to control the target LCoS chip to display blazed gratings of different periods; The diffraction optical path module is used to reflect the input light source signal to the target LCoS chip according to a preset diffraction optical path, and the blazed gratings of different periods displayed on the target LCoS chip diffract the received light source signal to generate diffracted light corresponding to the blazed gratings of different periods; The detection module is used to measure the optical signal intensity of the diffracted light corresponding to the blazed grating of each period, and send the optical signal intensity of the diffracted light corresponding to the blazed grating of each period to the processing module; The processing module is further used to determine the diffraction efficiency of the target LCoS chip according to the optical signal intensity of the diffracted light corresponding to the blazed grating of each period; Wherein, controlling the target LCoS chip to display blazed gratings of different periods includes: Obtain the relationship between wavelength and blaze angle in a pre-built blazed grating; According to the relationship between the wavelength and the blaze angle in the blazed grating, the minimum phase change, the variable coefficients corresponding to different diffraction orders and the diffraction angle are determined; wherein the diffraction angle is a fixed value, and the product of the phase change and the variable coefficients corresponding to the different diffraction orders is the phase difference between adjacent pixels; Determining the blazed grating of each period corresponding to the diffraction angle according to the variable coefficients corresponding to different diffraction orders; When the polarization angle of the collimating unit in the diffraction efficiency measuring device relative to the target LCoS chip is the diffraction angle, the blazed gratings of each period are sent to the target LCoS chip, and the target LCoS chip is controlled to display the blazed gratings of each period.

2. The device according to claim 1, characterized in that The diffraction optical path module includes: a ring unit, a collimation unit, a polarization unit and a mounting base; The mounting base is used to fix and mount the target LCoS chip; The annular unit is used to reflect the input light source signal to the collimating unit according to a preset first specified path; The collimating unit is used to collimate the light beam emitted by the annular unit into a parallel light beam, and send the parallel light beam to the polarization unit; The polarization unit is used to convert the parallel light beam into linear polarized light, and emit the linear polarized light to the target LCoS chip, and the blazed gratings of different periods displayed on the target LCoS chip diffract the linear polarized light to generate diffracted light corresponding to the blazed gratings of different periods, and reflect the diffracted light corresponding to the blazed gratings of different periods to the annular unit; The annular unit is further used to reflect the diffracted light corresponding to the blazed gratings of different periods to the detection module according to a preset second designated path.

3. The device according to claim 2, characterized in that The ring unit comprises: a three-port optical circulator, the three-port optical circulator comprises: a first port, a second port and a third port; The first designated path is used to indicate a transmission path from the first port to the second port; and the second designated path is used to indicate a transmission path from the second port to the third port.

4. The device according to claim 1, characterized in that The detection module includes: a light intensity sensor.

5. The device according to claim 1, characterized in that The step of determining the blazed grating of each period corresponding to the diffraction angle according to the variable coefficients corresponding to different diffraction orders comprises: Obtaining a pre-constructed expression of the phase value corresponding to each row of pixels in the blazed grating; Inputting the variable coefficients corresponding to the diffraction orders into the expression respectively to obtain the phase diagram of the blazed grating of each period; According to the pre-constructed grayscale-phase relationship of the target LCoS chip and the phase diagram of the blazed grating of each period, the grayscale diagram of the blazed grating of each period is obtained.

6. The device according to claim 1, characterized in that Determining the diffraction efficiency of the target LCoS chip according to the optical signal intensity of the diffracted light corresponding to the blazed grating of each period includes: Acquiring the initial optical signal strength of the target LCoS chip; Respectively determining the ratio of the light signal intensity of the diffracted light corresponding to the blazed grating of each period to the initial light signal intensity; The diffraction efficiency of the target LCoS chip is determined according to the ratio of the light signal intensity of the diffracted light corresponding to the blazed grating of each period to the initial light signal intensity.

7. The device according to claim 6, characterized in that The diffraction efficiency of the target LCoS chip includes: diffraction efficiencies of different diffraction orders.

8. The device according to claim 6, characterized in that The obtaining of the initial optical signal strength of the target LCoS chip comprises: When the polarization angle of the collimating unit in the diffraction efficiency measuring device relative to the target LCoS chip is zero, controlling the target LCoS chip to display a first grayscale test image, wherein the grayscale value of the first grayscale test image is 0; Controlling the target LCoS chip to display a plurality of second test grayscale images, wherein the grayscale of the second test grayscale images is a target value, and the target value is any value in the range of 0-255; The optical signal strength corresponding to each of the second test grayscale images detected by the detection module is acquired, and the initial optical signal strength of the target LCoS chip is determined according to the optical signal strength corresponding to each of the second test grayscale images.

9. The device according to claim 8, characterized in that The step of determining the initial optical signal intensity of the target LCoS chip according to the optical signal intensity corresponding to each of the second test grayscale images includes: Determine the average value of the optical signal strengths corresponding to each of the second test grayscale images, and use the average value as the initial optical signal strength of the target LCoS chip.

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