Grating detection method and detection device

Abstract

The embodiment of the invention discloses a grating detection method and device, and the method comprises the steps: 1, enabling the total displacement S of a grating horizontally operated on laser direct writing equipment at a theoretical uniform speed V to be equally divided into N segments of sub-displacements, and enabling the length of each segment of sub-displacement to be K mm; step 2, the FPGA module acquires three groups of data, namely, one group of grating signal direction detection result data, one group of grating signal pulse width detection result data and one group of grating signal filtering detection result data, in each time period when the grating runs for one section of sub-displacement; when the grating runs the total displacement S, the FPGA module collects 3 * N groups of data in total; and step 3, according to the 3 * N groups of data, judging whether the grating breaks down when passing through one section or several sections of the N sections of sub-displacement so as to decide whether to use or replace the grating. According to the grating detection method and the detection device, whether the grating breaks down or not can be judged, and a reference is provided for continuously keeping the grating for use or replacing the grating.

Description

Technical Field

[0001] The present invention belongs to the field of precision distance measuring instrument detection, and in particular relates to a grating detection method and a detection device. Background Art

[0002] Gratings are precision distance measuring instruments widely used in various applications. For example, in laser direct writing systems, gratings are required to detect the displacement of the moving laser to achieve high-precision positioning and prevent exposure errors. Therefore, it is crucial for gratings to possess precise displacement detection capabilities. Environmental factors such as dust, contamination, and temperature fluctuations can affect grating performance, reducing detection accuracy. Therefore, gratings must be tested before and after use to ensure their precise detection capabilities. Summary of the Invention

[0003] The present invention provides a grating detection method and a grating detection device, which aim to solve the technical problem of determining whether a grating meets usage requirements by detecting it before use or after use for a period of time.

[0004] The scheme of the present invention is as follows: A grating detection method, comprising: Step 1: The total displacement S of the grating running horizontally on the laser direct writing device at a theoretical uniform speed V is divided into N sub-displacements, each of which is K mm long. Step 2: During each sub-displacement period of the grating, the FPGA module collects three sets of data: one set of grating signal direction detection result data, one set of grating signal pulse width detection result data, and one set of grating signal filtering detection result data. When the grating completes the total displacement S, the FPGA module collects a total of 3*N sets of data. Step 3: Determine whether the grating fails when passing through one or more of the N segments of displacement based on the 3*N groups of data, so as to decide whether to use or replace the grating; The grating signal direction detection result data refers to: the FPGA module monitors the changes in the main signal and auxiliary signal output by the grating in real time when the grating passes through any sub-displacement, and compares the front and back directions: if the main signal is always 90° ahead of the auxiliary signal, the number of detection errors is counted as 0; otherwise, the number of detection errors is accumulated by one; there are N groups of grating signal direction detection result data, each group includes the following information: grating position information and the cumulative number of grating errors in the displacement segment; The grating signal pulse width detection result data refers to: when the grating passes through any sub-displacement, the FPGA module monitors in real time whether the actual pulse width of the grating is within the upper and lower range of the theoretical pulse width. If it is, the number of detection errors is counted as 0; if not, the number of detection errors is accumulated by one. The grating signal pulse width detection result data has N groups, each group includes: grating position information and the cumulative number of grating errors in the displacement section; The grating signal filtering detection result data refers to: when the grating passes through any sub-displacement, the FPGA module monitors the grating in real time and determines whether the grating signal delay before and after filtering exceeds the theoretical value. If it exceeds, the number of detection item errors is accumulated by one; otherwise, the number of detection item errors is counted as 0; there are N groups of grating signal filtering detection result data, each group includes: grating position information and the statistical cumulative number of grating errors in this displacement.

[0005] Furthermore, the grating signal filtering detection process is as follows: The FPGA module filters the grating signal; The grating digital signals before and after filtering are compared and detected at a detection frequency of 1-500Mhz to determine whether the grating signal delay before and after filtering exceeds the theoretical value.

[0006] Furthermore, after the grating undergoes a total displacement S, the storage system of the laser direct writing device stores N groups of grating signal direction detection result data, N groups of grating signal pulse width detection result data, and N groups of grating signal filtering detection result data together.

[0007] Furthermore, the theoretical pulse width of the grating is calculated by the following steps: Set the following parameters in the FPGA module: grating resolution H, theoretical uniform velocity V of the grating when it moves horizontally, and theoretical pulse width T of the grating, T=H / V; By using the grating self-test function, the upper and lower limits p of the grating pulse signal width are obtained, and the theoretical grating pulse width is calculated as T±p; The resolution H of the grating is equal to the exposure accuracy of the laser of the laser direct writing device. The higher the resolution H of the grating, the higher the exposure accuracy of the image.

[0008] The embodiment of the present application also discloses a grating detection device, comprising: an FPGA module, a storage module, and an analysis module; The FPGA module is used to collect three sets of data: one set of grating signal direction detection result data, one set of grating signal pulse width detection result data, and one set of grating signal filter detection result data. When the grating runs through the total displacement S, the FPGA module collects a total of 3*N sets of data. Storage module, used to store 3*N groups of data; The analysis module is used to determine whether the grating has a fault when it passes through one or more of the N segments of displacement based on 3*N groups of data, so as to decide whether to use or replace the grating; The grating signal direction detection result data refers to: the FPGA module monitors the changes in the main signal and auxiliary signal output by the grating in real time when the grating passes through any sub-displacement, and compares the front and back directions: if the main signal is always 90° ahead of the auxiliary signal, the number of detection errors is counted as 0; otherwise, the number of detection errors is accumulated by one; there are N groups of grating signal direction detection result data, each group includes the following information: grating position information and the cumulative number of grating errors in the displacement segment; The grating signal pulse width detection result data refers to: when the grating passes through any sub-displacement, the FPGA module monitors in real time whether the actual pulse width of the grating is within the upper and lower range of the theoretical pulse width. If it is, the number of detection errors is counted as 0; if not, the number of detection errors is accumulated by one. The grating signal pulse width detection result data has N groups, each group includes: grating position information and the cumulative number of grating errors in the displacement section; The grating signal filtering detection result data refers to: when the grating passes through any sub-displacement, the FPGA module monitors the grating in real time and determines whether the grating signal delay before and after filtering exceeds the theoretical value. If it exceeds, the number of detection item errors is accumulated by one; otherwise, the number of detection item errors is counted as 0; there are N groups of grating signal filtering detection result data, each group includes: grating position information and the statistical cumulative number of grating errors in this displacement.

[0009] Furthermore: the grating signal filtering detection process is: The FPGA module filters the grating signal; The grating digital signals before and after filtering are compared and detected at a detection frequency of 1-500Mhz to determine whether the grating signal delay before and after filtering exceeds the theoretical value.

[0010] Furthermore, after the grating undergoes a total displacement S, the storage module stores N groups of grating signal direction detection result data, N groups of grating signal pulse width detection result data, and N groups of grating signal filtering detection result data together.

[0011] Furthermore, the theoretical pulse width of the grating is calculated by the following steps: Set the following parameters in the FPGA module: grating resolution H, theoretical uniform velocity V of the grating when it moves horizontally, and theoretical pulse width T of the grating, T=H / V; By using the grating self-test function, the upper and lower limits p of the grating pulse signal width are obtained, and the theoretical grating pulse width is calculated as T±p; The resolution H of the grating is equal to the exposure accuracy of the laser of the laser direct writing device. The higher the resolution H of the grating, the higher the exposure accuracy of the image.

[0012] Beneficial technical effects of the present invention: The grating detection method and grating detection device disclosed in the embodiments of the present application can achieve the following technical effects: by using an FPGA module to collect three sets of data: a set of grating signal direction detection result data, a set of grating signal pulse width detection result data, and a set of grating signal filter detection result data; when the grating completes the total displacement S, the FPGA module collects a total of 3*N sets of data. Finally, the number of errors in the grating signal direction detection result data, the number of errors in the grating signal pulse width detection result data, and the number of errors in the grating signal filter detection result data within each displacement segment of the grating are counted, and based on this, it is determined whether the grating meets the use requirements. If it does, the grating is retained for continued use; if it does not, the grating is replaced and not used. Secondly, the specific position of the sub-displacement where the grating fails in a specific segment or segments of the total displacement of the grating can also be determined based on the detection results. If the grating is continued to be used, it is convenient to quickly calibrate the error position of the image exposure when subsequently exposing the image using a laser direct writing device. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 Schematic diagram of the structure of the laser direct writing device 100; Figure 2 Schematic diagram of the total displacement S of the grating being divided into N segments, each segment is K mm long; Figure 3 A diagram showing the steps of the method of the present invention; Figure 4 The waveform diagram of the main signal and auxiliary signal output by the grating; Figure 5 It is a module diagram of the storage system; Figure 6 It is the collected data of the direction detection result of some grating signals; Figure 7 It is the direction detection result data of part of the collected grating filter signal; Figure 8 It is the collected data of the direction detection result of part of the grating pulse width signal; Figure 9 This is a module diagram of a grating self-test device. DETAILED DESCRIPTION

[0014] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0015] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inside", "outside" and the like, indicating directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings and are only for the convenience of describing the present invention and simplifying the description. They do not indicate or imply that the devices or components referred to must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as limiting the present invention. The terms "first", "second", and "third" are only used to describe the difference and should not be understood as indicating or implying relative importance. In addition, unless otherwise expressly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, an indirect connection through an intermediate object, or the internal connection of two components. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood according to the specific circumstances.

[0016] refer to Figure 1 , the embodiment of the present application lists the scenario of grating application on the laser direct writing device 100. The laser direct writing device 100 includes: an upper horizontal guide rail assembly 101, a lower horizontal guide rail assembly 102, a vertical stand 103 and a laser motion assembly 104, and the upper and lower ends of the laser motion assembly 104 are respectively installed on the upper horizontal guide rail assembly 101 and the lower horizontal guide rail assembly 102. Between the upper horizontal guide rail assembly 101 and the lower horizontal guide rail assembly 102, a conveyor belt 106 is also arranged in parallel. The left and right ends of the conveyor belt 106 are respectively mounted on the motor 108 and the driven wheel 110. The laser motion assembly 104 is arranged on the conveyor belt 106. Under the control of the control module 109, the motor 108 drives the upper and lower ends of the laser motion assembly 104 to reciprocate left and right on the upper horizontal guide rail assembly 101 and the lower horizontal guide rail assembly 102 through the conveyor belt 106. In addition to several lasers (three lasers 105A, 105B, and 105C are shown in this example) mounted vertically in a row on the laser motion assembly 104, a grating 107 is also mounted. The grating 107 moves back and forth with the lasers, monitoring the displacement of the lasers. The total displacement of the grating 107 during a single horizontal movement (from left to right or from right to left) of the laser motion assembly 104 is defined as S. Figure 2 The total displacement S is evenly divided into N sub-displacements, each with a length of K millimeters. The value of K should not be too different from 1 millimeter. The size of K needs to be kept the same as the exposure accuracy of the laser of the laser direct writing device, that is, the same as the resolution of the exposed image. In theory, only if the grating 107 works normally in the N sub-displacements and timely and accurately monitors the displacement passed by the laser, can the laser light be accurately emitted and the image be accurately exposed. Therefore, it is particularly important to detect whether the grating 107 works normally during the exposure process.

[0017] In order to verify whether the grating can work normally during the exposure process of the laser, some detection items are needed to detect the grating when running in each sub-displacement.

[0018] Reference Figure 3 The embodiment of the present application discloses a grating detection method, which comprises: Step 1, the total displacement S of the grating horizontally passing through the laser direct writing device at a theoretical uniform speed V is evenly divided into N sub-displacements, each with a length of K millimeters. Step 2, the FPGA module collects three groups of data in each time period when the grating runs in a sub-displacement: one group of grating signal direction detection result data, one group of grating signal pulse width detection result data and one group of grating signal filtering detection result data; when the grating runs through the total displacement S, the FPGA module collects 3*N groups of data in total; Step 3, whether the grating appears a fault when passing through one or several sub-displacements is analyzed according to the 3*N groups of detection result data, so as to decide whether to use or replace the grating; The grating signal direction detection result data refers to that the FPGA module monitors the change of the main signal and the auxiliary signal output by the grating when passing through any sub-displacement, and compares the front and back directions: if the front and back are consistent, the error count of the detection item is 0; if not, the error count of the detection item in the detection result data is accumulated by one. There are N groups of grating signal direction detection result data, each of which includes the following information: the sub-displacement segment number passed by the grating and the accumulated error count of the segment. Figure 4 When the grating works, the main signal A (i.e. the red waveform diagram in the above row) and the auxiliary signal B (see the blue waveform diagram in the below row) are output. The main signal A and the auxiliary signal B are differential signals, and the waveform of the main signal A is about 90° ahead of the auxiliary signal B. At this time, the grating output signal is stable, and the error count of the detection item is 0. If the waveform of the main signal A is about 90° ahead of the auxiliary signal B, the main signal A and the auxiliary signal B appear unstable conditions, such as Figure 4The clutter signal appearing in the yellow box causes an error in the grating signal received by the laser system, further leading to an error in the displacement detected by the grating. This results in a detection error count of 1. It's understandable that within each K-mm displacement segment, the number of errors may be several or zero. The processing system counts the grating signal direction detection results within each K-mm displacement segment, calculating the total number of position information and corresponding errors, and stores these as a set of data. For N K-mm displacement segments, there are N sets of data.

[0019] refer to Figure 1 Due to the uneven speed of the laser motion assembly 104 of the laser direct writing device 100, the actual speed of the grating 107 mounted on the laser motion assembly 104 is not consistently consistent with the theoretical speed V. This, combined with the influence of the grating 107's internal self-correction algorithm, causes the grating signal pulse width to fluctuate with errors. Furthermore, due to external interference factors (ambient temperature differences, dust, and pollution), the grating signal pulse may experience sudden changes, causing the actual grating pulse width to exceed the theoretical grating pulse width.

[0020] refer to Figure 2 The grating signal pulse width detection result data refers to: when the grating passes through any sub-displacement (for example, the fourth sub-displacement between marks 3 and 4), the FPGA module monitors in real time whether the actual pulse width of the grating is within the upper and lower range of the theoretical pulse width. If it is, the number of detection errors is counted as 0; if not, the number of detection errors is accumulated by one; there are N groups of grating signal pulse width detection result data, each group includes: the number of sub-displacement segments that the grating passes through and the cumulative number of errors in that segment. It can be understood that Figure 1 The grating 107 in the Figure 2 When any sub-displacement of length K mm occurs, the number of errors in the detected items counted may be several or zero.

[0021] Specifically, the theoretical pulse width of the grating is calculated by the following steps: Set the following parameters in the FPGA module: grating resolution H, grating horizontal motion theoretical uniform speed V, grating theoretical pulse width T, T = H / V; By using the grating self-test function, the upper and lower limits p of the grating pulse signal width are obtained, that is, the theoretical grating pulse width is T±p.

[0022] The grating signal filtering detection result data refers to: the FPGA module monitors the grating in real time when it passes through any sub-displacement, and determines whether the grating signal delay before and after filtering exceeds the theoretical value. If it exceeds, the number of detection item errors is accumulated by one; otherwise, the number of detection item errors is counted as 0; there are N groups of grating signal filtering detection result data, each group includes: the number of sub-displacement segments passed by the grating and the cumulative number of errors in that segment.

[0023] It should be noted that the reference Figure 1 and Figure 5 As the grating 107 moves unidirectionally from one end of the conveyor belt 106 of the laser direct writing device 100 to the other (illustratively, from left to right), each time it passes through a sub-displacement K, three sets of data are collected and sent to the storage system for storage: one set of grating signal direction detection results data, which records the grating position information and the cumulative number of detection errors within that sub-displacement; one set of grating signal pulse width detection results data, which records the grating position information and the cumulative number of detection errors within that sub-displacement; and one set of grating signal filtering detection results data, which records the grating position information and the cumulative number of detection errors within that sub-displacement. After the grating 107 passes through N sub-displacements, the storage system will have stored 3*N sets of data.

[0024] These 3*N groups of data: grating signal direction detection result data, grating signal pulse width detection result data, and grating signal filter detection result data are ultimately classified, stored, and displayed. For example: after grating 107 has undergone N sub-displacements, the position of each displacement segment and the cumulative number of detection errors are displayed in sequence based on the grating signal direction detection result data; the position of each displacement segment and the cumulative number of detection errors are displayed in sequence based on the grating signal pulse width detection result data; and the position of each displacement segment and the cumulative number of detection errors are displayed in sequence based on the grating signal filter detection result data.

[0025] Finally, the stability of the grating operation is judged based on the statistical cumulative number of detection errors in one or several sections of the N-segment sub-displacement (based on the grating signal direction detection result data, the grating signal pulse width detection result data, and the grating signal filtering detection result data, or a combination of the three items) to decide whether to use the grating or replace it with a new one. At the same time, if the grating after this detection is used, the cumulative number of errors occurring at a certain position of the grating can also be used to assist the laser equipment in correcting image exposure errors occurring at that position during subsequent image exposure.

[0026] The following is a specific example: when the resolution H of the grating is 1 micron, Figure 2The above grating detection method is described in detail with the specific embodiment of each sub-displacement K being 1 mm. Since 1 mm = 1000 μm, when the grating passes through each sub-displacement of 1 mm in length, the number of errors counted ranges from 0 to 999, with a maximum of 999. Figure 6-8 , Figure 6-8 The first 24 segments of displacement are intercepted from the grating signal direction detection result data (it should be noted that the total grating displacement S is 696mm for example, with a total of 696 segments of displacement, thus including 696 sets of data. Due to display limitations, only the first 24 segments of displacement data are intercepted for example), the number of errors in the grating signal direction detection result statistics, the number of errors in the grating filter detection result statistics, and the number of errors in the grating signal pulse width detection result statistics. Figure 6-8 It can be seen that when the grating passes through each sub-displacement of the first 23 mm displacement, the error statistics of the grating signal direction detection are 0, the error statistics of the grating signal filtering detection are 0, and the error statistics of each sub-displacement of the grating signal pulse width detection are 999 times.

[0027] refer to Figure 9 , the embodiment of the present application also discloses a grating self-test device, including: an FPGA module, a storage module and an analysis module; The FPGA module is used to collect three sets of data: one set of grating signal direction detection result data, one set of grating signal pulse width detection result data, and one set of grating signal filter detection result data. When the grating runs through the total displacement S, the FPGA module collects a total of 3*N sets of data. The storage module is used to store 3*N groups of data; The analysis module is used to determine whether the grating has a fault when it passes through one or more of the N segments of displacement based on 3*N groups of data, so as to decide whether to use or replace the grating; The grating signal direction detection result data refers to: the FPGA module monitors the changes in the main signal and auxiliary signal output by the grating in real time when the grating passes through any sub-displacement, and compares the front and back directions: if they are consistent, the number of detection errors is counted as 0; if they are inconsistent, the number of detection errors is accumulated by one; there are N groups of grating signal direction detection result data, each group includes the following information: grating position information and the cumulative number of grating errors in the displacement segment; The grating signal pulse width detection result data refers to: when the grating passes through any sub-displacement, the FPGA module monitors in real time whether the actual pulse width of the grating is within the upper and lower range of the theoretical pulse width. If it is, the number of detection errors is counted as 0; if not, the number of detection errors is accumulated by one. The grating signal pulse width detection result data has N groups, each group includes: grating position information and the cumulative number of grating errors in the displacement section; The grating signal filtering detection result data refers to: when the grating passes through any sub-displacement, the FPGA module monitors the grating in real time and determines whether the grating signal delay before and after filtering exceeds the theoretical value. If it exceeds, the number of detection item errors is accumulated by one; otherwise, the number of detection item errors is counted as 0; there are N groups of grating signal filtering detection result data, each group includes: grating position information and the statistical cumulative number of grating errors in this displacement.

[0028] Specifically, the modules and specific functions of the grating detection device have been introduced in detail when introducing the grating detection method, and will not be repeated here.

[0029] The technical effect that can be achieved by the present grating detection method and grating detection device is: through the present grating detection method and grating detection device, it can be determined whether the grating meets the use requirements, so as to facilitate the selection of the grating for subsequent use or replacement of the grating.

[0030] Finally, it should be noted that the above are only preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or make equivalent replacements for some of the technical features therein. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A grating detection method, characterized in that: include: Step 1: The total displacement S of the grating running horizontally on the laser direct writing device at a theoretical uniform speed V is divided into N sub-displacements, each of which is K mm long. Step 2: During each sub-displacement period of the grating, the FPGA module collects three sets of data: one set of grating signal direction detection result data, one set of grating signal pulse width detection result data, and one set of grating signal filtering detection result data. When the grating completes the total displacement S, the FPGA module collects a total of 3*N sets of data. Step 3, judging whether the grating fails when passing through one or more of the N segments of sub-displacement based on the 3*N groups of data, so as to decide whether to use or replace the grating; The grating signal direction detection result data refers to: the FPGA module monitors the changes in the main signal and the auxiliary signal output by the grating in real time when the grating passes through any sub-displacement, and compares the front and back directions: if the main signal is always 90° ahead of the auxiliary signal, the number of detection errors is counted as 0; otherwise, the number of detection errors is accumulated by one; the grating signal direction detection result data has N groups, each group including the following information: grating position information and the cumulative number of grating errors in the displacement segment; The grating signal pulse width detection result data refers to: when the grating passes through any sub-displacement, the FPGA module monitors in real time whether the actual pulse width of the grating is within the upper and lower ranges of the theoretical pulse width. If so, the number of detection errors is counted as 0; if not, the number of detection errors is accumulated by one. The grating signal pulse width detection result data has N groups, each group including: grating position information and the cumulative number of grating errors in the displacement section; The grating signal filtering detection result data refers to: when the grating passes through any sub-displacement, the FPGA module monitors the grating in real time and determines whether the grating signal delay before and after filtering exceeds the theoretical value. If exceeded, the number of detection item errors is accumulated by one; otherwise, the number of detection item errors is counted as 0; there are N groups of grating signal filtering detection result data, each group includes: grating position information and the statistical cumulative number of grating errors in this displacement.

2. The grating detection method according to claim 1, wherein: The grating signal filtering detection process is: The FPGA module filters the grating signal; The grating digital signals before and after filtering are compared and detected at a detection frequency of 1-500Mhz to determine whether the grating signal delay before and after filtering exceeds the theoretical value.

3. The grating detection method according to claim 1, wherein: After the grating undergoes a total displacement S, the storage system of the laser direct writing device stores N groups of grating signal direction detection result data, N groups of grating signal pulse width detection result data, and N groups of grating signal filtering detection result data together.

4. The grating detection method according to claim 1, wherein: The theoretical pulse width of the grating is calculated by the following steps: Set the following parameters in the FPGA module: grating resolution H, theoretical uniform velocity V of the grating during horizontal motion, and theoretical pulse width T of the grating, where T = H / V. By using the grating self-test function, the upper and lower limits p of the grating pulse signal width are obtained, and the theoretical grating pulse width is calculated as T±p; The resolution H of the grating is equal to the exposure accuracy of the laser of the laser direct writing device. The higher the resolution H of the grating, the higher the exposure accuracy of the image.

5. A grating detection device, characterized in that: include: FPGA module, storage module and analysis module; The FPGA module is used to collect three sets of data: a set of grating signal direction detection result data, a set of grating signal pulse width detection result data, and a set of grating signal filtering detection result data; when the grating runs a total displacement S, the FPGA module collects a total of 3*N sets of data; The storage module is used to store 3*N groups of data; An analysis module is used to determine whether the grating fails when passing through one or more of the N segments of sub-displacement based on the 3*N groups of data, so as to decide whether to use or replace the grating; The grating signal direction detection result data refers to: the FPGA module monitors the changes in the main signal and the auxiliary signal output by the grating in real time when the grating passes through any sub-displacement, and compares the front and back directions: if the main signal is always 90° ahead of the auxiliary signal, the number of detection errors is counted as 0; otherwise, the number of detection errors is accumulated by one; the grating signal direction detection result data has N groups, each group including the following information: grating position information and the cumulative number of grating errors in the displacement segment; The grating signal pulse width detection result data refers to: when the grating passes through any sub-displacement, the FPGA module monitors in real time whether the actual pulse width of the grating is within the upper and lower ranges of the theoretical pulse width. If so, the number of detection errors is counted as 0; if not, the number of detection errors is accumulated by one. The grating signal pulse width detection result data has N groups, each group including: grating position information and the cumulative number of grating errors in the displacement section; The grating signal filtering detection result data refers to: when the grating passes through any sub-displacement, the FPGA module monitors the grating in real time and determines whether the grating signal delay before and after filtering exceeds the theoretical value. If exceeded, the number of detection item errors is accumulated by one; otherwise, the number of detection item errors is counted as 0; there are N groups of grating signal filtering detection result data, each group includes: grating position information and the statistical cumulative number of grating errors in this displacement.

6. The grating detection device according to claim 5, wherein: The grating signal filtering detection process is: The FPGA module filters the grating signal; The grating digital signals before and after filtering are compared and detected at a detection frequency of 1-500Mhz to determine whether the grating signal delay before and after filtering exceeds the theoretical value.

7. The grating detection device according to claim 5, wherein: After the grating undergoes a total displacement S, the storage module stores N groups of grating signal direction detection result data, N groups of grating signal pulse width detection result data, and N groups of grating signal filtering detection result data together.

8. The grating detection device according to claim 5, wherein: The theoretical pulse width of the grating is calculated by the following steps: Set the following parameters in the FPGA module: grating resolution H, theoretical uniform velocity V of the grating during horizontal motion, and theoretical pulse width T of the grating, where T = H / V. By using the grating self-test function, the upper and lower limits p of the grating pulse signal width are obtained, and the theoretical grating pulse width is calculated as T±p; The resolution H of the grating is equal to the exposure accuracy of the laser of the laser direct writing device. The higher the resolution H of the grating, the higher the exposure accuracy of the image.

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