A method, system and medium for evaluating substrate line error of computer generated hologram

Abstract

The present invention discloses a method, system and medium for evaluating the error of substrate line of a computer-generated hologram. The method comprises obtaining the substrate line measurement data obtained by detecting the n rows and m columns of equally spaced measuring points on the effective area of ​​the measured computer-generated hologram by using a white light interferometer; calculating the wavefront distortion error caused by the line depth error and the wavefront distortion error caused by the pattern distortion error, and arranging them according to the coordinate positions of the measuring points to obtain a discrete matrix of size n×m, and generating the error distribution diagram of the line depth error and the error distribution diagram of the pattern distortion error of the measured computer-generated hologram substrate according to the discrete matrix. The present invention aims to comprehensively and accurately quantify the accuracy of the effective area of ​​the computer-generated hologram, and use the results of this diagram to evaluate the accuracy of the manufacturing error of the effective area of ​​the CGH to guide the manufacturing of high-performance and accurate CGHs and realize high-precision zero-position compensation interferometry of aspheric optical elements.

Description

Technical Field

[0001] The present invention relates to the technical field of precision optical measurement, and in particular to a method, system and medium for evaluating substrate line errors of a computer generated hologram. Background Art

[0002] In optical systems, aspheric optical elements have the characteristics of compensating for phase differences, increasing design freedom, simplifying optical paths, and improving imaging quality. They have gradually replaced general planar and spherical optical elements. In order to meet normal use under extreme conditions, optical systems such as laser fusion systems, photolithography machines, and space telescopes have increasingly higher requirements for the surface shape accuracy of aspheric optical elements. Zero-position interferometry is a commonly used high-precision optical measurement method for optical elements. Its principle is to obtain the surface shape results of the measured optical element by solving the interference fringes generated by the superposition of the test wavefront and the reference wavefront. General wavefront interferometers can only produce plane or spherical wavefronts. For aspheric optical elements, an optical compensator is required to convert the plane or spherical reference wavefront into an aspheric wavefront with the same ideal surface shape as the measured aspheric surface to complete the zero-position measurement. Computer generated hologram (CGH) is a commonly used optical compensator and has been widely used in high-precision zero-compensation interferometry of high-order aspheric surfaces, such as ASML's extreme ultraviolet lithography objectives and the James Webb Space Telescope.

[0003] The interferometric measurement result of the zero-position interferometry method can be regarded as the superposition of the surface error of the interferometer lens and the surface error of the measured component. Since the peak-to-valley value (PV) of the interferometer lens is generally better than λ / 20 (λ=632.8nm), for optical components of general precision, the error introduced by the lens is small enough and can be ignored. However, when the surface accuracy reaches the nanometer or even sub-nanometer level, the error of the lens will have a huge impact on the measurement result and cannot be ignored. When using CGH to perform high-precision zero-position compensation interferometric measurement on aspheric optical components, CGH itself will also introduce new error terms to the interferometric measurement results, and the error introduced by CGH needs to be evaluated. The errors introduced by CGH are mainly divided into substrate errors and manufacturing errors. Substrate errors are related to the accuracy of the glass substrate itself and are easy to evaluate. Manufacturing errors mainly include line depth errors, pattern position distortion errors, etc., which are related to the actual lines on the substrate. Since the width of the lines is generally in the micrometer level, it is difficult to evaluate them using commonly used measurement methods. In addition, the line range is generally large relative to the measurement range, and it is difficult for general measurement methods to evaluate the overall error of the effective line area. White light interferometer, ultra-depth of field microscope, atomic force microscope, etc. are commonly used measuring equipment for measuring microstructures, and their characteristics are different. White light interferometer can be used to measure the three-dimensional morphology of the surface of components, with high accuracy, fast measurement speed, simple operation, but small measurement range. Ultra-depth of field microscope can only measure the two-dimensional morphology of the surface, with fast measurement speed, easy operation, and large measurement range. Atomic force microscope can measure the three-dimensional morphology of the surface of components, with high measurement accuracy and large measurement range, but slow measurement speed and difficult operation.

[0004] A Chinese patent document with publication number CN110285772A discloses a method for evaluating the detection accuracy of a computer generated holographic element. The method includes obtaining multiple microscopic images of a CGH sample as measurement image units, graying them respectively, extracting contour data points of the CGH stripes and calculating actual coordinate values. For each measurement image unit, the difference between the actual coordinate value and the design coordinate value of each contour feature point is compared to obtain the local position deviation, and the phase error introduced by each contour feature point is calculated. Based on all phase error statistics, the wavefront phase error PV value caused by the CGH pattern distortion and the wavefront phase error RMS value introduced by the pattern distortion are calculated. However, this method has the following disadvantages: (1) When measuring the CGH line area using an ultra-depth-of-field microscope, two-dimensional data is obtained, and the line depth information cannot be obtained, and the line depth error cannot be evaluated, so the CGH accuracy assessment is not comprehensive; (2) The number of measurements is small, and only the lines on a cross line passing through the center are selected for measurement and evaluation, and a specific assessment of the overall effective area of ​​the CGH cannot be made; (3) A micron-scale mark needs to be embedded in the CGH line area, and the mark needs to be searched during measurement, and the mark may affect the diffraction function of the CGH. Summary of the invention

[0005] Technical problem to be solved by the present invention: In view of the above-mentioned problems in the prior art, a method, system and medium for evaluating the substrate line error of a computer-generated hologram are provided. The present invention aims to perform a relatively comprehensive and accurate quantitative evaluation of the accuracy of the effective area of ​​the computer-generated hologram, and use the results of this figure to evaluate the accuracy of the manufacturing error of the CGH effective area to guide the manufacture of high-performance and accurate CGHs and realize high-precision zero-position interference compensation measurement of aspheric optical elements.

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0007] A method for evaluating substrate line errors of a computer-generated hologram comprises the following steps:

[0008] Obtain substrate line measurement data obtained by using a white light interferometer to detect n rows and m columns of equally spaced measurement points on an effective area of ​​a measured CGH;

[0009] Calculate the wavefront distortion error caused by the line depth error based on the substrate line measurement data of each measuring point Wavefront distortion error caused by pattern distortion error ;

[0010] The wavefront distortion error caused by the depth error of the markings at each measuring point is Wavefront distortion error caused by pattern distortion error The coordinate positions of the measuring points are arranged to obtain a discrete matrix of size n×m, and an error distribution diagram of the depth error of the measured CGI substrate and an error distribution diagram of the pattern distortion error are generated according to the discrete matrix.

[0011] Optionally, the substrate scribe line measurement data of each measuring point includes a scribe line depth error of each measuring point. , the wavefront distortion error caused by the line depth error The calculation function expression is:

[0012] ,

[0013] In the above formula, is the wavefront distortion error caused by the depth error of the ruled line, is the working wavelength of the measured CGH during compensation interferometry, is the phase change caused by the line depth error, and:

[0014] ,

[0015] In the above formula, Calculate the refractive index of the hologram for the measured value, is the line depth error.

[0016] Optionally, the depth error of the line at each measuring point is The acquisition includes:

[0017] Randomly select cross-sectional data of multiple vertical cross sections for the measuring point;

[0018] For each vertical section i, select a data point on the etched surface of the cross-sectional data of vertical section i and a data point on the non-etched surface , combined with the distance For all data points on vertical section i Perform data screening to reduce the impact of bat-wing errors, including: retaining the etched surface that meets Data points for , keep the non-etched surface to meet Data points for ; Delete the etched surface and non-etched surface that meet Data points ; The data points of the etched surface will be retained The y coordinate of Take the average value to get the average height A of the etched surface, and keep the data points on the non-etched surface The y coordinate of Take the average value to get the average height B of the non-etched surface; then subtract the average height A of the etched surface from the average height B of the non-etched surface to get the average depth H of the scribe line at the vertical section i. i ;

[0019] The average depth H of the score at each vertical section i i Take the average value to get the line depth H of the measuring point, according to Calculate the depth error of the measuring point ,in For the ideal scoring depth.

[0020] Optionally, the substrate scribe line measurement data of each measuring point includes a comprehensive position deviation of a measuring point area of ​​each measuring point. And the period of the substrate scribe line at the measuring point , the wavefront distortion error caused by the pattern distortion error The calculation function expression is:

[0021] ,

[0022] In the above formula, is the wavefront distortion error caused by the pattern distortion error, is the diffraction order used by the measured CGH in compensating interferometry, is the working wavelength of the measured CGH during compensation interferometry, is the comprehensive position deviation of the measuring point area, is the period of the substrate lines at the measuring point.

[0023] Optionally, the comprehensive position deviation of the measuring point area of ​​each measuring point The acquisition includes: selecting the scribed line profile on the horizontal section of D=H / 2 for the measuring point, where H is the scribed line depth of the measuring point, and D is the distance between the horizontal section and the etching surface; ... Feature points ~ And get each feature point The actual position in the measurement coordinate system , calculate the actual position The position deviation from the ideal position is obtained The position deviation of feature points ~ ,Will The position deviation of feature points ~ Take the root mean square RMS value to get the comprehensive position deviation of the measuring point area of ​​the measuring point .

[0024] Optionally, when the discrete matrix of size n×m is obtained by arranging the coordinate positions of the measuring points, a certain designated measuring point in the middle of the effective area of ​​the measured CGH is taken as the origin coordinate (0,0), and the remaining measuring points are determined according to the number of measurements adjacent to the designated measuring point in the horizontal direction, and the number of measurements adjacent to the designated measuring point in the vertical direction to determine the Y coordinate, thereby determining the coordinate position of each measuring point, and the wavefront distortion error caused by the depth error of the scribed line of each measuring point is calculated. According to the coordinate position of the measuring point, the wavefront distortion error caused by the depth error of the scribed line is obtained with a size of n×m. The corresponding discrete matrix converts the wavefront distortion error caused by the pattern distortion error of each measuring point into Arrange the measured points according to their coordinate positions to obtain the wavefront distortion error of size n×m caused by the pattern distortion error. The corresponding discrete matrix.

[0025] Optionally, it also includes the wavefront distortion error caused by the depth error of the scribed lines at each measuring point Wavefront distortion error caused by pattern distortion error Calculate the peak-to-valley value PV and the root mean square value RMS.

[0026] In addition, the present invention also provides a substrate line error evaluation device for a computer-generated hologram, comprising a measurement control computer, a white light interferometer, a motion adjustment platform and a motion controller, wherein the measurement control computer and the white light interferometer are interconnected, the motion adjustment platform and the motion controller are interconnected, a placement position or a fixture for placing the measured computer hologram is provided on the motion adjustment platform, the motion adjustment platform comprises an X-direction translation stage, a Y-direction translation stage and a pitch and yaw stage, the measurement control computer comprises an interconnected microprocessor and a memory, and the microprocessor is programmed or configured to execute the substrate line error evaluation method for the computer-generated hologram.

[0027] In addition, the present invention also provides a computer-readable storage medium, in which a computer program or instruction is stored. The computer program or instruction is programmed or configured to execute the substrate line error evaluation method of the computer generated hologram through a processor.

[0028] In addition, the present invention also provides a computer program product, comprising a computer program or instructions, which are programmed or configured to execute the substrate ruling line error evaluation method of the computer generated hologram through a processor.

[0029] Compared with the prior art, the present invention has the following advantages: (1) The manufacturing error of the computer-generated hologram (CGH) is mainly divided into the line depth error and the pattern distortion error. The present invention can measure and calculate the two errors at the same time, and calculate the wavefront distortion caused by the manufacturing error based on the two errors, so as to quantitatively evaluate the accuracy of the effective area of ​​the CGH in a relatively comprehensive manner. (2) Since the measurement range of the general instrument for measuring microstructures is small, a single or several measuring points cannot accurately evaluate the manufacturing error of the entire effective area of ​​the CGH. The measurement range of the present invention covers the entire effective area of ​​the CGH during measurement, so as to accurately evaluate the accuracy of the effective area of ​​the CGH in an overall manner. (3) The present invention discretizes the effective line area of ​​the CGH as a whole, regards the effective area as a discrete grid of n×m corresponding to the position of the measuring point, and arranges the calculated wavefront distortion error corresponding to the measuring point into the corresponding grid, finally forming an error distribution diagram of the effective area of ​​the CGH, and the result of this diagram is used to evaluate the accuracy of the manufacturing error of the effective area of ​​the CGH; (4) The present invention is suitable for CGH substrates of various line types including straight lines and irregular curves, and has good applicability to phase-type CGHs. The present invention can be used to evaluate the manufacturing error of CGH, thereby guiding the manufacturing of high-performance and high-precision CGH and realizing high-precision zero-position interference compensation measurement of aspheric optical elements. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1Schematic diagram of the basic flow of the method of the embodiment of the present invention.

[0031] Figure 2 It is a schematic diagram of the structure of the measured CGH in an embodiment of the present invention.

[0032] Figure 3 Detailed flowchart of the method of the embodiment of the present invention.

[0033] Figure 4 Schematic diagram of the grating measurement path and equally spaced measurement points in an embodiment of the present invention.

[0034] Figure 5 It is a schematic diagram of the top view and vertical cross section of the measurement line structure in the embodiment of the present invention.

[0035] Figure 6 It is a schematic diagram of data information after vertically intercepting the measuring point and eliminating the tilt in an embodiment of the present invention.

[0036] Figure 7 It is a schematic diagram of the side view and horizontal cross section of the measurement line structure in the embodiment of the present invention.

[0037] Figure 8 Schematic diagram of horizontally intercepting measurement point data information in an embodiment of the present invention.

[0038] Fig. 9 Graph showing the discrete error distribution obtained in the embodiment of the present invention.

[0039] Fig.10 Schematic diagram of the structure of the measuring device in the embodiment of the present invention.

[0040] Legend: 1. Measurement and control computer; 2. White light interferometer; 3. Motion adjustment platform; 31. X-direction translation stage; 32. Y-direction translation stage; 33. Pitch and yaw stage; 4. Motion controller. DETAILED DESCRIPTION

[0041] The substrate line error evaluation method of the computer-generated hologram of the present invention mainly uses a white light interferometer and adopts the idea of ​​discrete sampling to measure the CGH effective area, calculates the line depth error and pattern distortion error of the CGH according to the measurement data, and calculates the wavefront distortion caused by the line depth error and pattern distortion error accordingly, and then comprehensively evaluates the manufacturing error of the CGH effective area, thereby realizing high-precision zero-position interference compensation measurement of aspheric surfaces.

[0042] like Figure 1 As shown, the substrate line error evaluation method of the CGI hologram in this embodiment includes the following steps:

[0043] S1, obtaining substrate line measurement data detected by a white light interferometer at n rows and m columns of equally spaced measurement points on the effective area of ​​the measured CGH;

[0044] S2, calculate the wavefront distortion error caused by the line depth error based on the substrate line measurement data of each measuring point Wavefront distortion error caused by pattern distortion error ;

[0045] S3, the wavefront distortion error caused by the depth error of the line at each measuring point Wavefront distortion error caused by pattern distortion error The coordinate positions of the measuring points are arranged to obtain a discrete matrix of size n×m, and an error distribution diagram of the depth error of the measured CGI substrate and an error distribution diagram of the pattern distortion error are generated according to the discrete matrix.

[0046] like Figure 2 As shown, in this embodiment, the measured CGH substrate is a glass substrate, and the effective area (measurement holographic area) of the measured CGH is circular, with a concentric annular auxiliary holographic area provided outside.

[0047] like Figure 3 As shown, first of all, it is necessary to build a white light interferometer measurement device, which mainly includes a white light interferometer, a motion adjustment platform located on the lower side of the lens of the white light interferometer, and a motion controller for controlling the motion adjustment platform. The motion controller controls the position and posture of the object to be measured to meet the measurement requirements of the white light interferometer. The white light interferometer can measure the 3D structure of the CGH substrate scribed line and save it in the data storage device for subsequent processing of the measurement data. The motion adjustment platform has the functions of translation and pitch and yaw adjustment in the X and Y directions, and the motion error should be less than or equal to 0.2 microns. The magnification of the white light interferometer lens is determined according to the actual scribed line width, and generally a 20 or 50 times lens is used.

[0048] In this embodiment, when a white light interferometer is used to detect substrate line measurement data at n rows and m columns of equally spaced measurement points on the effective area of ​​the measured CGH, the substrate line measurement data obtained by the white light interferometer refers to the white light interferometer taking the grating path, such as Figure 4 As shown in the arrow path, the substrate line measurement data is obtained by performing n×m measurements on n rows and m columns (greater than 100) of equally distributed measurement points on the effective area of ​​the measured CGH, and the distance between adjacent measurement points in any row or column is the interval r, as shown in Figure 4This embodiment adopts a grating measurement path, the distances between adjacent measurement points are equal, and the number of measurement points is greater than 100. Therefore, during measurement, the measurement range covers the entire effective area of ​​the CGH, and the accuracy of the effective area of ​​the CGH can be more accurately evaluated as a whole.

[0049] In this embodiment, the substrate scribe line measurement data of each measuring point includes the scribe line depth error of each measuring point. , the wavefront distortion error caused by the line depth error The calculation function expression is:

[0050] ,

[0051] In the above formula, is the wavefront distortion error caused by the depth error of the ruled line, is the working wavelength of the measured CGH during compensation interferometry, is the phase change caused by the line depth error, and:

[0052] ,

[0053] In the above formula, Calculate the refractive index of the hologram for the measured value, is the line depth error.

[0054] In this embodiment, the depth error of the scribed line at each measuring point is The acquisition includes:

[0055] Step 1: randomly select a plurality of vertical cross-section data for the measuring point. The number of vertical cross-sections can be selected according to actual needs. For example, as an optional implementation, Figure 5 As shown, in this embodiment, the cross-sectional data of 5 vertical cross sections are randomly selected for the measuring point; if the cross-sectional data trend is in an inclined state, at least 8 points are selected from the data of the etched surface or the non-etched surface for linear fitting. After fitting the slope, the inclination is subtracted from all the data points to obtain the cross-sectional data after the inclination is eliminated, as shown in FIG. Figure 6 As shown;

[0056] Step 2: For each vertical section i, select a data point on the etched surface of the cross-sectional data of the vertical section i. and a data point on the non-etched surface , combined with the distance For all data points on vertical section i Perform data screening to reduce the impact of bat-wing errors, including: retaining the etched surface that meets Data points for , keep the non-etched surface to meet Data points for ; Delete the etched surface and non-etched surface that meet Data points , which can be expressed as:

[0057] ,

[0058] Through the above, the influence of bat-wing error can be reduced. The data points of the etched surface retained The y coordinate of Take the average value to get the average height A of the etched surface, assuming that the data points of the etched surface are retained Denoted as a1, a 2, a3,…,a n , then the data points a1, a 2, a3,…,a n The y coordinate of Take the average value to get the average height A of the etched surface. The y coordinate of Take the average value to get the average height B of the non-etched surface; Assume that the data points on the retained non-etched surface Denoted as b1, b 2, b3,…,b m , then the data points b1, b 2, b3,…,b m The y coordinate of The average height B of the non-etched surface is obtained by taking the average value. Then the average height A of the etched surface is subtracted from the average height B of the non-etched surface to obtain the average depth H of the scribe line at the vertical section i. i ;

[0059] Step 3: calculate the average depth H of each vertical section i. i Take the average value to get the line depth H of the measuring point, according to Calculate the depth error of the measuring point ,in is the ideal depth of the engraved line. In this embodiment, the cross-sectional data of 5 vertical cross sections are randomly selected for the measuring point, so the average engraved line depth H at each vertical cross section i is i The function expression of the line depth H of the measuring point obtained by taking the average value is:

[0060] ,

[0061] In the above formula, ~ They are the average score depths at 5 vertical sections.

[0062] In this embodiment, the substrate scribe line measurement data of each measuring point includes the comprehensive position deviation of the measuring point area of ​​each measuring point. And the period of the substrate scribe line at the measuring point , wavefront distortion error caused by pattern distortion error (line position deviation) The calculation function expression is:

[0063] ,

[0064] In the above formula, is the wavefront distortion error caused by the pattern distortion error, The diffraction order used by the measured CGH when performing compensation interferometry (usually 1 or -1), is the working wavelength of the measured CGH during compensation interferometry (e.g. the working wavelength of the zygo vertical interferometer is λ=632.8nm), is the comprehensive position deviation of the measuring point area, is the period of the substrate lines at the measuring point.

[0065] In this embodiment, the comprehensive position deviation of the measuring point area of ​​each measuring point is The acquisition includes: selecting the outline of the horizontal section with D=H / 2 for the measuring point, such as Figure 7 As shown, H is the depth of the line at the measuring point, D is the distance between the horizontal section and the etched surface, and the data of the line profile is as follows Figure 8 As shown; select the outline on the engraved line Feature points ~ And get each feature point The actual position in the measurement coordinate system , calculate the actual position The position deviation from the ideal position is obtained The position deviation of feature points ~ ,Will The position deviation of feature points ~ Take the root mean square value RMS to get the comprehensive position deviation of the measuring point area of ​​the measuring point .

[0066] In this embodiment, when the coordinate positions of the measuring points are arranged to obtain a discrete matrix of size n×m, a designated measuring point in the middle of the effective area of ​​the measured CGI is used as the origin coordinate (0,0), and the remaining measuring points are determined by the number of measurements adjacent to the designated measuring point in the horizontal direction and the number of measurements adjacent to the designated measuring point in the vertical direction, thereby determining the coordinate positions of each measuring point, for example, the coordinate of the first measuring point to the right of the origin coordinate (0,0) is (1,0), the coordinate of the first measuring point above the origin coordinate (0,0) is (0,1), and so on. The wavefront distortion error caused by the depth error of the scribed lines at each measuring point is calculated. According to the coordinate position of the measuring point, the wavefront distortion error caused by the depth error of the scribed line is obtained with a size of n×m. The corresponding discrete matrix converts the wavefront distortion error caused by the pattern distortion error of each measuring point into Arrange the measured points according to their coordinate positions to obtain the wavefront distortion error of size n×m caused by the pattern distortion error. The corresponding discrete matrix.

[0067] In this embodiment, the wavefront distortion error caused by the depth error of the scribed line at each measuring point is Wavefront distortion error caused by pattern distortion error According to the coordinate positions of the measuring points, a discrete matrix of size n×m is obtained, and the error distribution diagram of the depth error of the measured CGI substrate and the error distribution diagram of the pattern distortion error are generated according to the discrete matrix. The error distribution diagram in this embodiment uses the depth of color to represent the relative size of the value, such as Fig. 9 As shown, based on the error distribution diagram, the distribution of errors can be directly seen. For example, it is easy to see which area has a larger error and which area has a smaller error, which can be used to infer defects in the manufacturing process. In addition, when there are enough measuring points, the error distribution diagram can also be used as a diffraction wavefront phase error diagram of the measured CGH.

[0068] In addition, as an optional method, this embodiment also includes a wavefront distortion error caused by the depth error of the scribed line at each measuring point. Wavefront distortion error caused by pattern distortion error Calculate the peak-to-valley value PV and the root mean square value RMS. It should be noted that since the peak-to-valley value PV and the root mean square value RMS are both common surface error indicators, their specific calculation methods will not be described in detail here.

[0069] In summary, the substrate line error evaluation method of the CGH of this embodiment has the following advantages: (1) For general sampling measurement, the error of several measuring points is selected to evaluate the overall accuracy of the CGH, which may be insufficient. However, the method of this embodiment discretizes the effective area of ​​the CGH, regards the effective area as a discrete grid of n×m corresponding to the position of the measuring point, and arranges the calculated wavefront distortion error corresponding to the measuring point into the corresponding grid, and finally forms an error distribution map of the effective area of ​​the CGH. The result of this map is used to evaluate the accuracy of the manufacturing error of the effective area of ​​the CGH. (2) During measurement, the method of this embodiment performs equidistant measurement according to the grating path, the number of measuring points is greater than 100, and the measurement area covers the entire effective area of ​​the CGH. Each measuring point can represent the accuracy of a certain range of areas around the measuring point, calculates the line depth error and pattern distortion error of each measuring point, and calculates the wavefront distortion error caused by the error, which not only evaluates the manufacturing process accuracy of the CGH, but also evaluates the diffraction wavefront of the CGH in the working state. Calculating the PV and RMS values ​​of all measurement point errors can not only evaluate the accuracy of a small area of ​​CGH, but also evaluate the accuracy of the entire effective area of ​​CGH, which is more instructive for the high-precision manufacturing of CGH. (3) Generally, the raw data of the white light interferometer is directly used and the line analysis is directly performed in the corresponding analysis software. Only the height difference between an etched surface and an unetched surface can be obtained, which cannot reflect the average level of the line depth within a certain range around the measuring point. The method of this embodiment uses the method of setting the distance to screen the effective data points of the etched surface and the unetched surface, retaining as many data points as possible, which can effectively reduce the influence of the bat wing error and make the line depth calculation more accurate. (4) Generally, the two-dimensional projection of the upper end surface of the data is directly selected as the actual position of the line. For micrometer-level lines, the accuracy may not be enough. Since the actual scribed line may be trapezoidal or V-shaped instead of an ideal rectangle, the method of this embodiment uses a horizontal plane of D=H / 2 to intercept the measurement data to obtain the actual position information of the scribed line, which can effectively reduce the influence of the scribed line shape on the scribed line position, obtain a more realistic scribed line position, and increase the accuracy of pattern distortion error evaluation.

[0070] like Fig.10As shown, the present embodiment further provides a substrate line error evaluation device for a computer-generated hologram, comprising a measurement control computer 1, a white light interferometer 2, a motion adjustment platform 3 and a motion controller 4, wherein the measurement control computer 1 and the white light interferometer 2 are interconnected, the motion adjustment platform 3 and the motion controller 4 are interconnected, a placement position or a fixture for placing the computer-generated hologram to be measured is provided on the motion adjustment platform 3, the motion adjustment platform 3 comprises an X-direction translation stage 31, a Y-direction translation stage 32 and a pitch and yaw stage 33, the measurement control computer 1 comprises a microprocessor and a memory which are interconnected, and the microprocessor is programmed or configured to execute the aforementioned substrate line error evaluation method for the computer-generated hologram of the present embodiment.

[0071] In addition, this embodiment also provides a computer-readable storage medium, in which a computer program or instruction is stored. The computer program or instruction is programmed or configured to execute the substrate line error evaluation method of the aforementioned computer-generated hologram of this embodiment through a processor.

[0072] In addition, this embodiment also provides a computer program product, including a computer program or instructions, which are programmed or configured to execute the substrate ruling line error evaluation method of the aforementioned computer generated hologram of this embodiment through a processor.

[0073] Those skilled in the art should understand that the technical solutions provided by the embodiments of the present application may be in the form of methods, systems, or computer program products. Therefore, the present application may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present application may take the form of a computer program product implemented on one or more computer-readable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program codes. The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the process Figure 1 A process or multiple processes and / or boxes Figure 1 These computer program instructions can also be stored in a computer-readable memory that can guide a computer or other programmable data processing device to work in a specific way, so that the instructions stored in the computer-readable memory produce a product including an instruction device, which implements the functions specified in the process. Figure 1 A process or multiple processes and / or boxes Figure 1 These computer program instructions can also be loaded onto a computer or other programmable data processing device, so that a series of operation steps are executed on the computer or other programmable device to produce a computer-implemented process, so that the instructions executed on the computer or other programmable device provide for implementing the process in the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0074] The above is only a preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above embodiments. All technical solutions under the concept of the present invention belong to the protection scope of the present invention. It should be pointed out that for ordinary technicians in this technical field, some improvements and modifications without departing from the principle of the present invention should also be regarded as the protection scope of the present invention.

Claims

1. A method for evaluating substrate line error of a computer generated hologram, characterized in that: The steps include: Obtain substrate line measurement data obtained by using a white light interferometer to detect n rows and m columns of equally spaced measurement points on an effective area of ​​a measured CGH; Calculate the wavefront distortion error caused by the line depth error based on the substrate line measurement data of each measuring point Wavefront distortion error caused by pattern distortion error ; The wavefront distortion error caused by the depth error of the markings at each measuring point is Wavefront distortion error caused by pattern distortion error Arrange the measured points according to their coordinate positions to obtain a discrete matrix of size n×m, and generate an error distribution diagram of the depth error of the measured CGI substrate and an error distribution diagram of the pattern distortion error according to the discrete matrix; The substrate scribe line measurement data of each measuring point includes the scribe line depth error of each measuring point , the wavefront distortion error caused by the line depth error The calculation function expression is: ， In the above formula, is the wavefront distortion error caused by the depth error of the ruled line, is the working wavelength of the measured CGH during compensation interferometry, is the phase change caused by the line depth error, and: ， In the above formula, Calculate the refractive index of the hologram for the measured value, is the depth error of the engraved line; The substrate scribe line measurement data of each measuring point includes the comprehensive position deviation of the measuring point area of ​​each measuring point And the period of the substrate scribe line at the measuring point , the wavefront distortion error caused by the pattern distortion error The calculation function expression is: ， In the above formula, is the wavefront distortion error caused by the pattern distortion error, is the diffraction order used by the measured CGH in compensating interferometry, is the working wavelength of the measured CGH during compensation interferometry, is the comprehensive position deviation of the measuring point area, is the period of the substrate lines at the measuring point.

2. The method for evaluating substrate line error of a computer generated hologram according to claim 1, characterized in that: The depth error of the scale line at each measuring point The acquisition includes: Randomly select cross-sectional data of multiple vertical cross sections for the measuring point; For each vertical section i, select a data point on the etched surface of the cross-sectional data of vertical section i and a data point on the non-etched surface , combined with the distance For all data points on vertical section i Perform data screening to reduce the impact of bat-wing errors, including: retaining the etched surface that meets or Data points for , keep the non-etched surface to meet or Data points for ; Delete the etched surface and non-etched surface that meet and Data points ; The data points of the etched surface will be retained The y coordinate of Take the average value to get the average height A of the etched surface, and keep the data points on the non-etched surface The y coordinate of Take the average value to get the average height B of the non-etched surface; then subtract the average height A of the etched surface from the average height B of the non-etched surface to get the average depth H of the scribe line at the vertical section i. i ; The average depth of the score line H at each vertical section i is i Take the average value to get the line depth H of the measuring point, according to Calculate the depth error of the measuring point ,in For the ideal scoring depth.

3. The method for evaluating substrate line error of a computer generated hologram according to claim 1, characterized in that: The comprehensive position deviation of the measuring point area of ​​each measuring point The acquisition includes: selecting the scribed line profile on the horizontal section of D=H / 2 for the measuring point, where H is the scribed line depth of the measuring point, and D is the distance between the horizontal section and the etching surface; ... Feature points ~ And get each feature point The actual position in the measurement coordinate system , calculate the actual position The position deviation from the ideal position is obtained The position deviation of feature points ~ ,Will The position deviation of feature points ~ Take the root mean square value RMS to get the comprehensive position deviation of the measuring point area represented by the measuring point .

4. The method for evaluating substrate line error of a computer generated hologram according to claim 1, characterized in that: When the discrete matrix of size n×m is obtained by arranging the coordinate positions of the measuring points, a certain measuring point in the middle of the effective area of ​​the measured CGH is taken as the origin coordinate (0,0), and the remaining measuring points are determined according to the number of measurements adjacent to the designated measuring point in the horizontal direction, and the number of measurements adjacent to the designated measuring point in the vertical direction. The coordinate position of each measuring point is determined, and the wavefront distortion error caused by the depth error of the scribed line of each measuring point is calculated. According to the coordinate position of the measuring point, the wavefront distortion error caused by the depth error of the scribed line is obtained with a size of n×m. The corresponding discrete matrix converts the wavefront distortion error caused by the pattern distortion error of each measuring point into Arrange the measured points according to their coordinate positions to obtain the wavefront distortion error of size n×m caused by the pattern distortion error. The corresponding discrete matrix.

5. The method for evaluating substrate ruling errors of a computer generated hologram according to claim 1, characterized in that: It also includes the wavefront distortion error caused by the depth error of the scribed lines at each measuring point Wavefront distortion error caused by pattern distortion error Calculate the peak-to-valley value PV and the root mean square value RMS.

6. A substrate line error evaluation device for a computer generated hologram, characterized in that: The invention comprises a measurement control computer (1), a white light interferometer (2), a motion adjustment platform (3) and a motion controller (4), wherein the measurement control computer (1) and the white light interferometer (2) are interconnected, the motion adjustment platform (3) and the motion controller (4) are interconnected, the motion adjustment platform (3) is provided with a placement position or a fixture for placing a computer generated hologram to be measured, the motion adjustment platform (3) comprises an X-direction translation stage (31), a Y-direction translation stage (32) and a pitch and tilt stage (33), the measurement control computer (1) comprises a microprocessor and a memory interconnected, the microprocessor is programmed or configured to execute the substrate line error evaluation method of the computer generated hologram according to any one of claims 1 to 5.

7. A computer-readable storage medium having a computer program or instruction stored therein, characterized in that: The computer program or instruction is programmed or configured to execute the substrate ruling error evaluation method of a computer generated hologram as claimed in any one of claims 1 to 5 through a processor.

8. A computer program product comprising a computer program or instructions, characterized in that The computer program or instruction is programmed or configured to execute the substrate ruling error evaluation method of a computer generated hologram as claimed in any one of claims 1 to 5 through a processor.

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