Bending correction method of moving mirror, interferometer measurement system and storage medium

Abstract

The invention discloses a bending correction method of a mobile reflector, an interferometer measurement system and a storage medium. The method comprises the following steps: calculating a bending difference value of each measurement point of the mobile reflector; removing a tilt component from the bend difference; interpolation processing is carried out on the bending difference values after the inclination components are removed, and correction values distributed at preset intervals are generated; and compensating the correction value to a displacement calculation result of the interferometer measurement system. According to the embodiment of the invention, the error of the measurement tail end is corrected, and the problem of high data processing difficulty in related technologies is solved.

Description

Technical Field

[0001] The present application relates to a bending correction method for a moving mirror, an interferometer measurement system and a storage medium, belonging to the field of laser measurement. Background Art

[0002] In semiconductor applications, high-precision moving displacement measurement mostly uses a laser interferometer system, and its accuracy can reach the nanometer level or even the sub-nanometer level. As a key optical device in the interferometer system, the moving mirror has extremely high processing accuracy requirements. In actual use, the moving mirror is fixed near the object to be measured, and its surface processing accuracy and deformation directly affect the measurement result. Therefore, how to reduce or eliminate the influence of deformation is crucial.

[0003] Ideally, the moving mirror should have no bending, but it is inevitable to have slight deformation after actual installation and fastening, and environmental changes or movements may also cause deformation. Most related technologies use algorithm post-processing to measure data, but this method has high requirements for data processing and does not perform compensation and correction from the system error source. Summary of the Invention

[0004] In view of this, the present application provides a bending correction method for a moving mirror, an interferometer measurement system and a storage medium. The embodiments of the present application correct from the error at the measurement end, and solve the problem of high data processing difficulty in related technologies.

[0005] The first aspect of the embodiments of the present application discloses a bending correction method for a moving mirror, and the method includes: Calculating the bending difference of each measurement point of the moving mirror; Removing the tilt component from the bending difference; Performing interpolation processing on the bending difference after removing the tilt component to generate correction values distributed at a preset interval; Compensating the correction values into the displacement calculation result of the interferometer measurement system.

[0006] In an embodiment, the calculating the bending difference of each measurement point of the moving mirror includes: Controlling the moving stage to move at a fixed step distance in the first direction; Reading the measurement values of two measurement axes in the second direction at each step position and calculating the bending difference. The two measurement axes include a first measurement axis and a second measurement axis, and the bending difference represents the increase or decrease value of the measurement value of the first measurement axis relative to the second measurement axis in the step position.

[0007] In an embodiment, before calculating the bending difference, it further includes: Obtaining the tilt data of the moving mirror and performing yaw correction on the measurement values.

[0008] In one embodiment, obtaining the tilt data of the movable mirror and performing yaw correction on the measurement values includes: Correcting the measurement values by the bending difference between two measurement axes in the first direction.

[0009] In one embodiment, removing the tilt component from the bending difference includes: For all bending differences, connecting the first and last shape points to obtain the tilt component; Removing the tilt component from each shape point.

[0010] A second aspect of the embodiments of the present application discloses an interferometer measurement system, the system includes: A transmitting unit configured to transmit a laser including a first polarized light and a second polarized light; An optical path unit including a polarization beam splitter, a movable mirror, a fixed mirror, and a 1 / 4λ polarizer. The polarization beam splitter guides the first polarized light to the movable mirror and the second polarized light to the fixed mirror. After the two beams of light are processed by the 1 / 4λ polarizer, the movable mirror and the fixed mirror are used to realize the beam return, forming a double-channel optical path and a double-pass optical path difference; A detection unit including an interference measurement axis; A processing unit configured to perform photoelectric conversion on the double-channel interference signal and used to execute the bending correction method of the above embodiment.

[0011] In one embodiment, the first polarized light is a vertically polarized light, the second polarized light is a horizontally polarized light, and the frequencies of the first polarized light and the second polarized light are different.

[0012] In one embodiment, the polarization beam splitter is disposed on the outgoing optical path of the transmitting unit and configured to divide the laser into the first polarized light and the second polarized light; The movable mirror and the fixed mirror respectively receive the first polarized light and the second polarized light, and return the corresponding beams of light to the polarization beam splitter to form a detection area, and the normal directions of their mirror surfaces are orthogonal to each other; The 1 / 4λ polarizers are respectively disposed in the incident optical paths of the movable mirror and the fixed mirror and are located between the corresponding mirrors and the polarization beam splitter.

[0013] In one embodiment, the detection unit includes four interference measurement axes and is configured to be symmetrically arranged in a first direction and a second direction.

[0014] A third aspect of the embodiments of the present application discloses a computer-readable storage medium, wherein the computer-readable storage medium includes a stored program, wherein when the program is executed, a processor of a device is controlled to execute the bending correction method of the above embodiment.

[0015] Compared with the prior art, the embodiments of the present application have the following beneficial effects: The embodiment of the present application provides a bending correction method for a movable reflector, an interferometer measurement system, and a storage medium. The bending correction method includes: calculating the bending difference of each measurement point of the movable reflector; removing the tilt component from the bending difference; interpolating the bending difference after removing the tilt component to generate correction values ​​distributed at preset intervals; and compensating the correction values ​​to the displacement calculation results of the interferometer measurement system. The embodiment of the present application can be used to correct the bending of the movable mirror of the interferometer, improve the displacement measurement accuracy, reduce the measurement error, and reduce the difficulty of subsequent data processing. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying any creative work.

[0017] Figure 1 A schematic diagram of a curved movable mirror provided in an embodiment of the present application.

[0018] Figure 2 A schematic diagram of a corrected movable mirror provided in an embodiment of the present application.

[0019] Figure 3 A structural block diagram of an optical path provided in an embodiment of the present application.

[0020] Figure 4 A schematic diagram of four interferometric measurement axes provided in an embodiment of the present application.

[0021] Figure 5 A flow chart of a method for correcting the bending of a movable reflector provided in an embodiment of the present application.

[0022] Figure 6 A schematic diagram of round-trip motion detection provided in an embodiment of the present application.

[0023] Figure 7 A schematic diagram of yaw data compensation provided in an embodiment of the present application.

[0024] Figure 8A schematic diagram of shape data calculation provided by an embodiment of this application.

[0025] Figure 9 A schematic diagram of multiple shape points provided by an embodiment of this application.

[0026] Figure 10 A schematic diagram of shape points after removing the tilt component provided by an embodiment of this application.

[0027] Figure 11 A schematic diagram of tilt data calculation provided by an embodiment of this application.

[0028] Figure 12 A schematic diagram of tilt measurement points and shape measurement points provided by an embodiment of this application.

[0029] Figure 13 A schematic diagram of the shape of the mirror after shape point interpolation provided by an embodiment of this application.

[0030] Figure 14 A structural block diagram of a bending correction device for a moving mirror provided by an embodiment of this application. Detailed implementation manners

[0031] In order to enable those skilled in the art to better understand the solution of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0032] It should be noted that the terms "first", "second", etc. in the description and claims of the present invention and the above drawings are used to distinguish similar objects, and do not necessarily need to describe a specific order or sequence. It should be understood that such used data can be interchanged under appropriate circumstances so that the embodiments of the present invention described here can be implemented in an order different from those illustrated or described here. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device that includes a series of steps or units does not necessarily have to be limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0033] Embodiment 1: In semiconductor applications, laser interferometer systems are mostly used for high-precision motion displacement measurement, and their accuracy can reach the nanometer level or even the sub-nanometer level. The moving mirror in the interferometer system, as a key optical device, requires extremely high machining accuracy. During actual use, the moving mirror is fixed near the object to be measured, and the machining accuracy and deformation of its surface directly affect the measurement results. Therefore, how to reduce or eliminate the influence of deformation is crucial.

[0034] Ideally, the moving mirror should have no bending, but it is inevitable to have slight deformation after actual installation and fastening, and environmental changes or motion may also cause deformation, such as Figure 1 shown. Most of the related technologies use algorithm post-processing to measure data, but this method has high requirements for data processing and does not perform compensation and correction from the system error source.

[0035] To solve this problem, the embodiments of this application propose the following solutions to achieve Figure 2 the bending correction effect shown.

[0036] Figure 3 The structural block diagram of an interferometer measurement system provided by the embodiments of this application is shown in Figure 3 as shown. The interferometer measurement system includes: a transmitting unit 301 configured to transmit a laser including a first polarized light and a second polarized light; an optical path unit including a polarization beam splitter 3021, a moving mirror 3022, a fixed mirror 3023, and a 1 / 4λ polarization plate 304. The polarization beam splitter (specifically, a polarization beam splitter prism) guides the first polarized light to the moving mirror and the second polarized light to the fixed mirror. After the two beams of light are processed by the 1 / 4λ polarization plate, the moving mirror and the fixed mirror (specifically, a corner cube) are used to realize the beam return, forming a dual-channel optical path and a double-pass optical path difference; a detection unit 303 including an interference measurement axis for measuring the dual-channel interference signal in region A; a processing unit configured to perform photoelectric conversion on the dual-channel interference signal and used to execute the bending correction method of this embodiment.

[0037] The above-mentioned polarization beam splitter prism is a common optical element that can split the incident light into two orthogonally polarized lights (such as P light and S light), and is widely used in laser systems, interferometers, imaging, and other fields.

[0038] The above-mentioned corner cube is a common optical element, and its core characteristic is that it can accurately reflect the incident light along the original path without being affected by the incident angle.

[0039] The above-mentioned 1 / 4λ polarization plate is a common optical element that can introduce a phase delay to light of a specific wavelength, thereby changing the polarization state of the light. It has wide applications in laser systems, optical measurements, communications, and other fields.

[0040] In some embodiments, the first polarized light is vertically polarized light, the second polarized light is horizontally polarized light, and the frequencies of the first polarized light and the second polarized light are different.

[0041] In some embodiments, the polarization beam splitter is disposed on the light path of the outgoing light of the emitting unit and configured to divide the laser into the first polarized light and the second polarized light; the movable mirror and the fixed mirror respectively receive the first polarized light and the second polarized light and reflect the corresponding light beams back to the polarization beam splitter, and the normal directions of their mirror surfaces are orthogonal to each other; the 1 / 4λ polarization plate is respectively disposed in the incident light paths of the movable mirror and the fixed mirror and is located between the corresponding mirror and the polarization beam splitter.

[0042] In this embodiment, the polarization beam splitter is configured to: transmit the first polarized light to the movable mirror; reflect the second polarized light to the fixed mirror; the first polarized light is vertically polarized light, and the second polarized light is horizontally polarized light; the 1 / 4λ polarization plate is disposed in front of the light paths of the movable mirror and the fixed mirror and is configured to: convert the first polarized light into the first left circularly polarized light; convert the second polarized light into the first right circularly polarized light; the movable mirror and the fixed mirror are configured to: reverse the phase (change the phase by 180°) of the first left circularly polarized light and the first right circularly polarized light through reflection and respectively convert them into the second right circularly polarized light and the second left circularly polarized light; the 1 / 4λ polarization plate is configured to: convert the second right circularly polarized light into horizontally polarized light and convert the second left circularly polarized light into vertically polarized light. It can be understood that the horizontally polarized light is transmitted through the polarization beam splitter and enters the corner cube, and the vertically polarized light is reflected by the polarization beam splitter and enters the corner cube. After being processed by the corner cube (changing the light path direction), the two light beams return to the polarization beam splitter again, completing the second light path round trip and forming a double-pass interference measurement light path.

[0043] When the movable mirror moves, corresponding interference signals will be left in area A, which are used as the basis for bending measurement.

[0044] In one embodiment, the interferometer measurement system is composed of the following units: (1) Laser unit: including a laser head and an emitting unit, emitting two orthogonally polarized light beams.

[0045] (2) Optical path unit: including a reference optical path and a detection optical path, for measuring the optical path difference caused by laser transmission and the displacement of the moving stage.

[0046] (3) Detection unit: including a signal receiver and a relay control board, receiving the laser signal and performing preprocessing.

[0047] (4) Processing unit: including an interferometer axis card and a measurement control board, which converts optical signals into electrical signals and calculates displacements.

[0048] In some embodiments, the detection unit includes four interferometric axes, configured to be symmetrically arranged in a first direction and a second direction.

[0049] In this embodiment, as Figure 4 shown, there are two measurement axes (xl and xr, yl and yr, or represented by XL and XR, YL and YR) for the measurement axes in the horizontal X direction and the vertical Y direction respectively.

[0050] In this embodiment, an overview of the moving mirror bending correction method: Detect the bending of the moving mirror through the interferometer (xl, xr, yr, yl measurement axes) of the wafer stage. When the center of the wafer chuck is directly below the projection lens (the origin position of the wafer stage): Measurement method: Centered on the position of the wafer stage, measure 8 specified positions of the moving mirror in the X / Y directions respectively; Data type: It is necessary to synchronously obtain shape data (mirror surface profile deviation) and tilt data (local angle change); Correction process: Based on the measurement results, calculate the bending correction values of the moving mirror in the X / Y directions at intervals of 1.29 mm and implement compensation.

[0051] Figure 5 is a flowchart of a bending correction method for a moving mirror provided by an embodiment of the present application. As Figure 5 shown, the bending correction method includes: S501 Calculate the bending difference values of the respective measurement points of the moving mirror.

[0052] In this step, the calculating the bending difference values of the respective measurement points of the moving mirror includes: S5011 Control the moving stage to move at a fixed step distance in a first direction.

[0053] S5012 Read the measurement values of two measurement axes in a second direction at each step position and calculate the bending difference value. The two measurement axes include a first measurement axis and a second measurement axis, and the bending difference value represents the increase or decrease value of the measurement value of the first measurement axis relative to the second measurement axis at the step position.

[0054] Specifically, as Figure 6As shown, the wafer stage 30 includes an X-direction moving mirror 10 and a Y-direction moving mirror 20. Taking the Y-direction moving mirror as an example, the wafer stage steps 7 times at intervals of 35 mm in the X direction (corresponding to the installation spacing between the interferometers yl and yr), obtaining eight measurement points, namely ①, ②, ③, ④, ⑤, ⑥, ⑦, and ⑧, and recording the readings of yl and yr at each position, and taking the average value through round-trip measurement.

[0055] Specifically, as Figure 8 shown, at each measurement point (shape data counting point), the difference P (shape data) is calculated according to the values of the interferometers yl and yr, which represents the increase or decrease value in yl relative to the yr value, P(i) = yr(i) - yl(i), yl(i): the measurement value of the yl interferometer, yr(i): the measurement value of the yr interferometer, i: the shape measurement serial number, 1 ≤ i ≤ 7. In this embodiment, the shape measurement count is 7, which can be understood as the number of points involving shape changes.

[0056] Specifically, as Figure 9 shown, assuming the initial value is 0, and the shape measurement value P is cumulatively calculated in sequence from 1 to 7, then the shape points P of the moving mirror of the wafer stage can be plotted at intervals of 35 mm, P(1) = 0, P(i + 1) = .

[0057] In this embodiment, before calculating the bending difference, it further includes: Obtaining the tilt data of the moving mirror and performing yaw correction on the measurement value.

[0058] Possibly, the tilt data of the moving mirror is obtained through a neural network algorithm.

[0059] Further, the obtaining the tilt data of the moving mirror and performing yaw correction on the measurement value includes: Correcting the measurement value through the bending difference between two measurement axes in the first direction.

[0060] Specifically, as Figure 7 shown, the yaw error compensation is performed on the yr and yl values using the tilt angle calculated by the difference D and the installation spacing between xr and xl.

[0061] S502 removes the tilt component from the bending difference.

[0062] In this step, the removing the tilt component from the bending difference includes: S5021 For all bending differences, connect the first and last shape points to obtain the tilt component.

[0063] S5022 Remove the tilt component at each shape point.

[0064] Specifically, Figure 9The head and end of the shape points are connected by a straight line to obtain the tilt component of the moving mirror of the wafer stage, and it is removed from each shape point to obtain as Figure 10 the image shown.

[0065] S503 performs interpolation processing on the bending difference after removing the tilt component to generate correction values distributed at preset intervals.

[0066] In this embodiment, as Figure 11 and Figure 12 shown, the tilt data of the moving mirror is measured, and it is used as the interpolation of the shape point information calculated from the shape data. Each measurement point is placed at the center positions of the interferometers yl and yr, and their respective values are read. Specifically, according to the values of the interferometers yl and yr read, the difference S (tilt data) between the two is calculated, S(i)=yr(i)-yl(i), yl(i): measurement value of the yl interferometer, yr(i): measurement value of the yr interferometer, i: tilt measurement serial number, 1≤i≤8. At this time, yaw correction can be performed on the values of yl and yr, similar to the shape data measurement step of the above embodiment. It should be noted that different from the shape data measurement step of the above embodiment, the measurement point positions are changed in this step. For other embodiments, the measurement point positions may not be changed.

[0067] In one embodiment, spline interpolation and correction value calculation: 1. According to all 8 shape points in the X direction obtained by measurement ((xi(k), yi(k)), 1≤k≤8) and the tilt data (s(k), 1≤k≤8), calculate the interpolation polynomial of the shape point interval.

[0068] 2. Interpolate the shape points through the interpolation polynomial of each interval [xi(k)≤x≤xi(k + 1), 1≤k≤7] of the shape points, as Figure 13 shown.

[0069] 3. Calculate the shape of the moving mirror of the wafer stage according to the interpolation polynomial of each interval to calculate correction values at intervals of 1.29 mm in the X direction.

[0070] 4. Calculate the correction value for the X-direction moving mirror with reference to the above method.

[0071] S504 compensates the correction values into the displacement calculation result of the interferometer measurement system.

[0072] Embodiment 2: Figure 14 is a schematic structural diagram of a bending correction device for a moving mirror provided by an embodiment of the present application. As Figure 14 shown, the bending correction device includes: A calculation module 1401 for calculating the bending differences of the measurement points of the movable mirror.

[0073] A removal module 1402 for removing the tilt component from the bending differences.

[0074] A generation module 1403 for performing interpolation processing on the bending differences after removing the tilt component to generate correction values distributed at a preset interval.

[0075] A compensation module 1404 for compensating the correction values into the displacement calculation result of the interferometer measurement system.

[0076] Embodiment 3: An embodiment of the present application further provides an electronic device, including: a memory storing an executable program; a processor for running the program, wherein when the program runs, it executes the methods in the various embodiments of the present invention.

[0077] The above-mentioned memory may refer to a device inside a computer for storing data and programs, which may include a memory, a hard disk, etc. Among them, the memory can be used for temporarily storing the running programs and data, and the hard disk can be used for long-term storing programs and data. The memory can be used to enable the computer to read and write data and execute programs; the above-mentioned processor can be responsible for executing the instructions in the computer program and performing data processing, and can be responsible for controlling and executing various operations, including arithmetic operations, logical operations, data transmission, etc.

[0078] Embodiment 4: An embodiment of the present application further provides a computer-readable storage medium, the computer-readable storage medium includes a stored executable program, wherein when the executable program runs, it controls the device where the computer-readable storage medium is located to execute the methods in the various embodiments of the present invention.

[0079] The above-mentioned computer storage medium may refer to a medium in a computer memory for storing a certain discontinuous physical quantity. The computer storage medium mainly includes semiconductors, magnetic cores, magnetic drums, magnetic tapes, laser discs, etc.; the stored program included in the computer-readable storage medium can be a set of instructions that can be recognized and executed by a computer, running on an electronic computer, and is an information tool to meet people's certain needs.

[0080] Embodiment 5: An embodiment of the present application further provides a computer program product, including a computer program, and the computer program realizes the methods in the various embodiments of the present invention when executed by a processor.

[0081] The above computer program product may refer to a software program that has been written, tested, and released, and can run on a computer or other device. The computer program product may include application programs, operating systems, tool software, etc., and is used to implement specific functions or solve specific problems.

[0082] Example 6: An embodiment of the present application further provides a computer program product, including a non-volatile computer-readable storage medium for storing a computer program, and the computer program, when executed by a processor, implements the methods in various embodiments of the present invention.

[0083] The above non-volatile computer-readable storage medium may refer to a medium for storing data. The non-volatile computer-readable storage medium can retain data without loss when powered off and can be used to store data for long-term preservation, such as operating systems, application programs, and user files. The non-volatile storage medium may include hard disk drives, solid-state drives, optical discs, and flash storage devices, etc.

[0084] Example 7: An embodiment of the present application further provides a computer program, and the computer program, when executed by a processor, implements the methods in various embodiments of the above present invention.

[0085] The above computer program may refer to a set of instructions for telling a computer to perform specific tasks or operations. The computer program can be written by a programmer using a specific programming language and may include algorithms, data structures, logic, and control flows, etc. The computer program can be used for various purposes, including application software, operating systems, etc.

[0086] In the above embodiments of the present invention, the descriptions of the various embodiments each have their own focuses. For the parts not detailed in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0087] In the several embodiments provided by the present application, it should be understood that the disclosed technical content can be implemented in other ways. Among them, the device embodiments described above are merely illustrative. For example, the division of the units can be a logical function division, and there can be other division methods in actual implementation. 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 couplings or direct couplings or communication connections shown or discussed with each other can be through some interfaces, and the indirect couplings or communication connections of the units or modules can be in an electrical or other form.

[0088] The unit described as a separation component may or may not be physically separated. The component shown as a unit may or may not be a physical unit, that is, it may be located in one place or may be distributed over multiple units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0089] In addition, each functional unit in various embodiments of the present invention may be integrated into a processing unit, may exist separately as individual physical units, or two or more units may be integrated into one unit. The above-mentioned integrated unit can be implemented in the form of hardware or in the form of a software functional unit.

[0090] If the above-mentioned integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on such an understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions for causing a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods described in various embodiments of the present invention. The aforementioned storage medium includes: USB flash drives, read-only memories (ROMs), random access memories (RAMs), mobile hard disks, magnetic disks, or optical discs and other various media that can store program codes.

[0091] The above description is only a preferred embodiment of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A method for correcting the bending of a movable reflector, characterized in that: include: Calculating the bending difference of each measuring point of the movable reflector; removing a tilt component from the bend difference; interpolating the bending difference after removing the tilt component to generate correction values ​​distributed at preset intervals; The correction value is compensated into the displacement calculation result of the interferometer measurement system.

2. The bending correction method according to claim 1, characterized in that: The calculating the bending difference of each measuring point of the movable reflector comprises: Controlling the motion stage to move in a first direction with a fixed step distance; At each step position, the measurement values ​​of two measurement axes in the second direction are read and the bending difference is calculated. The two measurement axes include a first measurement axis and a second measurement axis. The bending difference represents the increase or decrease of the measurement value of the first measurement axis relative to the second measurement axis at the step position.

3. The bending correction method according to claim 2, characterized in that: Before calculating the bending difference, the method further includes: The tilt data of the movable reflector is acquired and the yaw correction is performed on the measured value.

4. The bending correction method according to claim 3, characterized in that: The step of acquiring the tilt data of the movable reflector and performing yaw correction on the measured value comprises: The measured values ​​are corrected by the difference in curvature of the two measuring axes in a first direction.

5. The bending correction method according to claim 1, characterized in that: The removing the tilt component from the bending difference comprises: For all bending differences, connect the first and last shape points to obtain the tilt component; The tilt component is removed from each shape point.

6. An interferometer measurement system, characterized in that: include: An emitting unit configured to emit a laser light including a first polarized light and a second polarized light; An optical path unit, comprising a polarization beam splitter, a movable reflector, a fixed reflector and a 1 / 4λ polarizing plate, wherein the polarization beam splitter directs the first polarized light to the movable reflector, and the second polarized light to the fixed reflector, and after the two beams of light are processed by the 1 / 4λ polarizing plate, the movable reflector and the fixed reflector realize beam folding, thereby forming a dual-channel optical path and a secondary round-trip optical path difference; A detection unit including an interferometric measurement axis; A processing unit is configured to perform photoelectric conversion on the dual-channel interference signal and is used to execute the bending correction method described in any one of claims 1 to 5.

7. The interferometer measurement system according to claim 6, characterized in that: The first polarized light is vertically polarized light, the second polarized light is horizontally polarized light, and the frequency of the first polarized light is different from the frequency of the second polarized light.

8. The interferometer measurement system according to claim 6, characterized in that: The polarization beam splitter is disposed on the outgoing light path of the emitting unit and is configured to split the laser into the first polarized light and the second polarized light; The movable reflector and the fixed reflector receive the first polarized light and the second polarized light respectively, and return the corresponding light beams to the polarization beam splitter to form a detection area, and the normal directions of the two mirror surfaces are orthogonal to each other; The 1 / 4λ polarizing plates are respectively arranged in the incident light paths of the movable reflector and the fixed reflector, and are located between the corresponding reflector and the polarization beam splitter.

9. The interferometer measurement system according to claim 6, characterized in that: The detection unit includes four interference measurement axes configured to be symmetrically arranged in a first direction and a second direction.

10. A computer-readable storage medium, characterized in that: The computer-readable storage medium includes a stored program, wherein when the program is executed, the bending correction method according to any one of claims 1 to 5 is executed in a processor of a device where the program is controlled.

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