Optical alignment verification system and method

Abstract

The present application relates to the field of optical measurement technology, and particularly to an optical alignment verification system and method. The system comprises a collimator, a light source module, a guide rail, a camera, a scanning element, a slide, an image processing module, a reference calibration module, a deviation determination module and a visual graphical user interface. The method is based on the above system, first acquires the light spot images at two different positions on the guide rail, obtains the light spot center coordinates, the reference line and the theoretical center point of the reference line; adjusts the posture of the collimator, calculates the deviation between the measured light spot center coordinates and the theoretical center point, generates a quantitative adjustment suggestion according to the deviation, physically adjusts the collimator until the deviation meets the preset threshold condition. The present application integrates light spot measurement, deviation evaluation and adjustment guidance functions, can quickly and actively suppress the beam transverse shift error, and solves the problem of insufficient initial measurement accuracy and inability to effectively implement subsequent error suppression of the traditional method.

Description

Technical Field

[0001] This invention belongs to the field of optical measurement technology, and particularly relates to an optical alignment verification system and an optical alignment verification method. Background Technology

[0002] In the field of ultra-high precision optical surface inspection, such as the slope or surface shape measurement of optical components like large-aperture plane mirrors and X-ray mirrors, the deflection scanning method is a core technology. It typically uses a pentaprism as the scanning element, and its measurement accuracy needs to reach the nano-arc level. However, this accuracy is limited by the optical quality and assembly status of the inspection system itself, mainly including surface shape errors of the optical components, transmission wavefront distortion caused by material inhomogeneities, system aberrations, and system alignment errors.

[0003] In actual scanning measurements, the guide rail driving the pentaprism inevitably has parallelism and straightness errors, causing minute attitude changes in the pentaprism during movement. This attitude change causes a lateral displacement (BLM) in the optical path of the measurement beam within the pentaprism and other optical components. Due to microscopic surface shape errors and material inhomogeneities on the surface of optical components, additional, nonlinear wavefront distortion or deflection errors are introduced when the beam passes through the same optical component at different positions. This beam lateral displacement error is strongly coupled with guide rail errors and optical component errors, becoming one of the main bottlenecks restricting the measurement system from achieving nanoradian-level accuracy.

[0004] Currently, the common approach to alignment issues in such scanning systems is manual visual recognition. This involves using a laser attachment to an autocollimator to create a spot on the target surface or observation screen. Operators then directly observe the position or offset of this spot and manually adjust it based on experience. This method has significant drawbacks: the spot diameter is typically around 1 mm, limiting human eye alignment accuracy (only reaching the millimeter level), resulting in poor repeatability. Furthermore, it relies entirely on the operator's subjective judgment and experience, failing to provide precise, objective, and quantifiable deviation data. Therefore, it is difficult to meet the high-precision requirements for suppressing nanoradian-level BLM errors.

[0005] In summary, the shortcomings of existing technologies are as follows: 1. Insufficient precision and objectivity: Relying entirely on the operator's visual judgment, the alignment accuracy is limited to the millimeter level, failing to provide stable, quantifiable, and objective deviation data, resulting in measurement results that vary from person to person and have poor repeatability; 2. Low-precision measurement leads to the failure of suppression measures: Due to the low accuracy of the initial judgment, any subsequent mechanical adjustments based on this will inevitably have limited final suppression accuracy, failing to achieve "pixel-level" (corresponding to microradian / nanoradian level) precision control, thus making it difficult to effectively suppress beam lateral movement errors caused by minute alignment deviations; 3. Opaque process and lack of controllability: The entire alignment process is highly dependent on personal experience, belonging to a "black box" operation, lacking real-time, intuitive quantitative feedback and visual guidance, failing to form an effective "measurement-evaluation-adjustment" closed loop, resulting in low process efficiency and unreproducible state. Summary of the Invention

[0006] In view of this, the present invention aims to provide an optical alignment verification system and optical alignment verification method to suppress beam lateral shift error, effectively improve alignment efficiency, and reduce the requirements for operator experience.

[0007] To achieve the above objectives, the technical solution created by this invention is implemented as follows: An optical alignment verification system includes: an autocollimator, a light source module, a guide rail, a camera, a scanning element, a slider, an image processing module, a reference calibration module, and a deviation determination module; The light source module is mounted on the autocollimator and is used to generate the test beam; The guide rail is a horizontal straight structure, and the slider is slidably connected to the guide rail. Its sliding direction is parallel to the propagation direction of the test beam. Both the scanning element and the camera are fixedly mounted on the slider. After the test beam passes through the scanning element, it is incident on the camera to acquire the light spot image. An image processing module is used to identify the center coordinates of the light spot in the light spot image; The reference calibration module is used to calibrate the straight line segment formed by the center coordinates of the two light spots as a reference line based on the center coordinates of the two light spots obtained by the image processing module when the slider is in two different preset positions, and to obtain the theoretical center point of the reference line. The deviation determination module is used to calculate the deviation between the center coordinates of the actual measured light spot and the theoretical center point.

[0008] Furthermore, the optical alignment verification system also includes a visual graphical user interface, which displays in real time the spot image captured by the camera, the spot markers in the spot image, the baseline, the theoretical center point, the deviation auxiliary diagram, and adjustment suggestions.

[0009] Furthermore, the deviation auxiliary diagrams include tolerance label diagrams and deviation data diagrams; The tolerance marking diagram consists of concentric rings of different colors arranged with the theoretical center point as the center and different preset pixel tolerances as the radii, as well as error lines; the error lines are straight line segments between the theoretical center point and the measured light spot center point. The deviation data graph is used to display the pixel values ​​of the deviation and the actual angular deviation and / or actual linear deviation converted from the deviation; the deviation includes the deviation vector and the deviation value; The actual angular deviation is the angle between the error line and the horizontal or vertical direction; The actual line deviation is the product of the deviation value and the camera's single-pixel resolution size: The adjustment recommendations are to provide an attitude adjustment scheme for the autocollimator based on the actual angular deviation and / or the actual linear deviation.

[0010] Furthermore, the optical alignment verification system also includes a verification process recording module, which is used to record deviations during the optical alignment verification process and the spot image of the completed optical alignment verification, and generate an alignment verification report.

[0011] Furthermore, the light source module is a laser or a structured light generator.

[0012] Furthermore, the scanning element is a pentaprism, a galvanometer, or a rotating mirror.

[0013] Furthermore, the camera is either a CCD camera or a CMOS camera.

[0014] An optical alignment verification method, implemented based on an optical alignment verification system, includes the following steps: S1: Slide the slider to position A, which is closer to the light source module on the guide rail, and use the camera to capture the light spot image at this time as the first reference image; use an image processing algorithm to calculate the center coordinates of the light spot in the first reference image. ; S2: Slide the slider to position B, the end of the guide rail furthest from the light source module, and use the camera to capture the light spot image at this point, which will serve as the second reference image; use an image processing algorithm to calculate the center coordinates of the light spot in the second reference image. ; S3: In the first reference image coordinate system, the center coordinates and Using the straight line segment formed as a baseline, calculate the coordinates of the theoretical center point M of the baseline. ; S4: Adjust the attitude of the autocollimator to align the measured light spot with the theoretical center point M, acquire the light spot image at this point, and obtain the center coordinates of the measured light spot in the light spot image. ; S5: Calculate center coordinates The deviation from the theoretical center point M; if the deviation is not greater than the preset deviation threshold, the optical alignment verification is completed; if the deviation is greater than the preset deviation threshold, the attitude of the autocollimator is readjusted, and steps S4 to S5 are repeated.

[0015] Furthermore, in step S1 or step S2, the image processing algorithm is a brightness threshold segmentation combined with region analysis.

[0016] Furthermore, the deviation includes the deviation vector. and deviation values ; Deviation vector The calculation formula is: ; Deviation value The calculation formula is: .

[0017] Compared with the prior art, the present invention can achieve the following beneficial effects: This invention utilizes a camera to acquire test spot images, improving alignment verification accuracy from millimeter-level to sub-pixel-level. It eliminates interference from subjective human judgment, providing stable, repeatable, and quantifiable deviation data to ensure the consistency and reliability of measurement results. Simultaneously, a visual interface enables real-time feedback and operational guidance, transforming experience-dependent, non-standardized operations into controllable, standardized processes. This improves alignment efficiency while reducing the reliance on operator experience. This invention integrates spot measurement, deviation assessment, and adjustment guidance functions, enabling rapid and proactive suppression of beam lateral movement errors. It solves the problems of insufficient initial measurement accuracy and ineffective subsequent error suppression in traditional methods. Attached Figure Description

[0018] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments and descriptions of the invention are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings: Figure 1 A schematic diagram of the optical alignment verification system described in the embodiments of the present invention; Figure 2 A schematic diagram illustrating the tolerance marking principle described in the embodiments of the present invention; Figure 3 A schematic flowchart of the optical alignment verification method described in the embodiments of the present invention; Figure 4 A schematic diagram illustrating the principle of spot image recognition in the optical alignment verification method described in the embodiments of the present invention.

[0019] Explanation of reference numerals in the attached figures: 1. Autocollimator; 2. Light source module; 3. Guide rail; 4. Camera; 5. Scanning element; 6. Slider. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and do not constitute a limitation thereof.

[0021] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0022] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this invention. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, features defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0023] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art will understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0024] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0025] like Figure 1 As shown, this embodiment of the invention provides an optical alignment verification system, including an autocollimator 1, a light source module 2, a guide rail 3, a camera 4, a scanning element 5, a slider 6, an image processing module (not shown), a reference calibration module (not shown), and a deviation determination module (not shown). The light source module 2 is mounted on the autocollimator 1 and is used to generate the test beam; In some embodiments, the light source module 2 may be a laser or a structured light generator.

[0026] The guide rail 3 is a horizontal straight structure, and the slider 6 is slidably connected to the guide rail 3. Its sliding direction is parallel to the propagation direction of the test beam.

[0027] Both the scanning element 5 and the camera 4 are fixedly mounted on the slider 6. After the test beam passes through the scanning element 5, it is incident on the camera 4 to acquire the light spot image. In some embodiments, the scanning element 5 may be a pentaprism, a galvanometer, or a rotating mirror; In some embodiments, camera 4 may be a CCD camera or a CMOS camera.

[0028] The image processing module is used to identify the center coordinates of the light spot in the light spot image.

[0029] The reference calibration module is used to calibrate the straight line segment formed by the center coordinates of the two light spots as a reference line based on the center coordinates of the two light spots obtained by the image processing module when the slider 6 is in two different preset positions, and to obtain the theoretical center point of the reference line.

[0030] The deviation determination module is used to calculate the deviation between the center coordinates of the actual measured light spot and the theoretical center point.

[0031] The optical alignment verification system of this invention also includes a visual graphical user interface (not shown in the figure), which is used to display in real time the spot image acquired by the camera 4, the spot mark in the spot image, the baseline, the theoretical center point, the deviation auxiliary diagram and the adjustment suggestions.

[0032] In some embodiments, the deviation auxiliary diagram includes a tolerance identification diagram and a deviation data diagram; the tolerance identification diagram consists of concentric rings of different colors arranged with the theoretical center point as the center and different preset pixel tolerances as the radii, as well as error lines; the error lines are straight line segments between the theoretical center point and the center point of the measured light spot. Figure 2 This is a schematic diagram of the tolerance marking principle provided in an embodiment of the present invention. The red ring represents the position of 15 pixels tolerance from the theoretical center point, the yellow ring represents the position of 10 pixels tolerance from the theoretical center point, and the green ring represents the position of 5 pixels tolerance from the theoretical center point. The different colored rings represent the magnitude of the deviation.

[0033] The deviation data graph is used to display the pixel values ​​of the deviation and the actual angular deviation and / or actual line deviation converted from the deviation; the deviation includes the deviation vector and the deviation value.

[0034] The actual angular deviation is the angle between the error line and the horizontal or vertical direction.

[0035] The actual line deviation is the product of the deviation value and the single-pixel resolution size of camera 4.

[0036] The adjustment suggestions can provide an attitude adjustment scheme for autocollimator 1 based on the actual angular deviation and / or actual linear deviation, such as "X direction deviation +10 pixels, it is recommended to finely adjust the autocollimator 1 adjustment frame around the vertical axis in the negative direction of angle α".

[0037] The visual graphical user interface provides users with visual assessments and precise quantitative guidance.

[0038] The optical alignment verification system of this invention also includes a verification process recording module (not shown in the figure), which is used to record deviations during the optical alignment verification process and the spot image after the optical alignment verification is completed, and to generate an alignment verification report. The verification process recording module is used for process traceability and quality analysis of optical alignment verification. The verified optical alignment verification system can be directly used for subsequent high-precision optical scanning measurements, ensuring that the measurement results are not affected by BLM errors.

[0039] like Figures 3 to 4 As shown, combined with Figure 1 This invention also provides an optical alignment verification method, implemented based on the aforementioned optical alignment verification system, comprising the following steps: S1: Slide slider 6 to position A near the end of guide rail 3 close to light source module 2, and use camera 4 to capture the light spot image at this time as the first reference image; use image processing algorithm to calculate the center coordinates of the light spot in the first reference image. .

[0040] Slide slider 6 to position A near the end of guide rail 3 closest to light source module 2, meaning both camera 4 and scanning element 5 are at position A corresponding to slider 6. Fine-tune the parameters of camera 4 to ensure the image of the light spot acquired by camera 4 is clear and has optimal imaging quality. Control camera 4 to acquire the image of the light spot at this time, save it as the first reference image, and use image processing algorithms to automatically detect the light spot and calculate its sub-pixel-level center coordinates in the image coordinate system. .

[0041] In some embodiments, the image processing algorithm is a brightness threshold segmentation combined with region analysis.

[0042] S2: Slide slider 6 to position B, the end of guide rail 3 furthest from light source module 2, and use camera 4 to capture the light spot image at this time as the second reference image; use image processing algorithm to calculate the center coordinates of the light spot in the second reference image. .

[0043] Slide slider 6 to position B on guide rail 3, away from light source module 2, so that camera 4 and scanning element 5 are both at position B corresponding to slider 6. The orientation of camera 4 and scanning element 5 remains unchanged during use. Control camera 4 to acquire an image of the light spot at this time, save it as a second reference image, and use an image processing algorithm to automatically detect the light spot and calculate its sub-pixel-level center coordinates in the first reference image coordinate system. .

[0044] In some embodiments, the image processing algorithm is a brightness threshold segmentation combined with region analysis.

[0045] Since the image processing algorithms in steps S1 and S2 are existing technologies, they will not be described in detail in this invention.

[0046] S3: In the first reference image coordinate system, the center coordinates and Using the straight line segment formed as a baseline, calculate the coordinates of the theoretical center point M of the baseline. .

[0047] S4: Adjust the attitude of the autocollimator 1 to align the measured light spot with the theoretical center point M, acquire the light spot image at this point, and obtain the center coordinates of the measured light spot in the light spot image. .

[0048] The theoretical center point M is the center of the light spot at position A. The center of the light spot at position B The geometric midpoint represents the intermediate reference position of the light spot drift trajectories at positions A and B. By adjusting the attitude of the autocollimator 1, the emitted test beam is changed from its tilted state before adjustment to an aligned state parallel to the sliding direction of the guide rail 3. At this time, when the slider 6 slides along the guide rail 3, the test beam no longer experiences significant lateral drift relative to the scanning element 5, and the center of the light spot at positions A and B tends to coincide.

[0049] S5: Calculate the center coordinates in step S4 The deviation from the theoretical center point M; if the deviation is not greater than the preset deviation threshold, the optical alignment verification is completed; if the deviation is greater than the preset deviation threshold, the attitude of the autocollimator 1 is readjusted, and steps S4 to S5 are repeated.

[0050] Deviation includes deviation vector and deviation values Deviation vector The calculation formula is: ; Deviation value The calculation formula is: .

[0051] This deviation vector and deviation values All measurements are in pixels, with a repeatability better than 0.1 pixels. This objectively quantifies the alignment error caused by beam lateral movement error at that position, changing the situation of relying on subjective estimation by the human eye.

[0052] When the center coordinates of the measured light spot are adjusted When the deviation from the theoretical center point M is not greater than the preset deviation threshold, it indicates that the lateral drift caused by the test beam emitted from the light source module 2 not being parallel to the guide rail 3 has been suppressed within the allowable range, thus determining that the optical alignment verification is complete.

[0053] In some embodiments, the preset deviation threshold can be 1 to 2 pixels. When the deviation is not greater than the preset deviation threshold, the beam lateral movement error of the optical alignment verification system is effectively suppressed, and the optical alignment is considered qualified, allowing for formal measurement. When the deviation is greater than the preset threshold, the autocollimator 1 is physically adjusted according to the adjustment suggestions given by the optical alignment verification system. For example, the pitch and / or yaw adjustment frame of the autocollimator 1 is finely adjusted, and steps S4 to S5 are repeated until the deviation meets the preset threshold condition. This adjustment process can actively suppress the system's beam lateral movement (BLM) to within the allowable range.

[0054] The deviation directly reflects the trend and magnitude of the beam's lateral displacement caused by factors such as guide rail 3 error. The system displays this deviation in real time through a visual interface and provides precise adjustment guidance to guide operators or automatic mechanisms to adjust the system, thereby physically suppressing BLM error.

[0055] The optical alignment verification system and method of the present invention can not only be used to suppress beam lateral shift error, but can also be widely applied to any optical system that requires high-precision beam pointing alignment, optical axis calibration or motion trajectory verification, such as optical path calibration of laser processing equipment, precise positioning of secondary mirrors of astronomical telescopes, and alignment of optical communication terminals.

[0056] It should be understood that the various forms of processes shown above can be used to reorder, add, or delete steps. For example, the steps described in this invention disclosure can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution disclosed in this invention can be achieved, and this is not limited herein.

[0057] The specific embodiments described above do not constitute a limitation on the scope of protection of this invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. An optical alignment verification system, characterized in that, include: Autocollimator, light source module, guide rail, camera, scanning element, slider, image processing module, reference calibration module and deviation judgment module; The light source module is mounted on the autocollimator and is used to generate a test beam; The guide rail is a horizontal straight structure, and the slider is slidably connected to the guide rail, with its sliding direction parallel to the propagation direction of the test beam; Both the scanning element and the camera are fixedly mounted on the slider. The test beam passes through the scanning element and is then incident on the camera to acquire a light spot image. The scanning element is a pentaprism, a galvanometer, or a rotating mirror. An image processing module is used to identify the center coordinates of the light spot in the light spot image; The reference calibration module is used to calibrate the straight line segment formed by the center coordinates of the two light spots as a reference line based on the center coordinates of the two light spots obtained by the image processing module when the slider is in two different preset positions, and to obtain the theoretical center point of the reference line. The deviation determination module is used to calculate the deviation between the center coordinates of the actual measured light spot and the theoretical center point; A visual graphical user interface is used to display in real time the spot image captured by the camera, the spot markers in the spot image, the baseline, the theoretical center point, the deviation auxiliary diagram, and adjustment suggestions; The deviation auxiliary diagram includes a tolerance label diagram and a deviation data diagram; The tolerance marking diagram consists of concentric rings of different colors arranged with the theoretical center point as the center and different preset pixel tolerances as the radii, as well as error lines; the error lines are straight line segments between the theoretical center point and the center point of the measured light spot. The deviation data graph is used to display the deviation and the actual angular deviation and / or actual linear deviation converted from the deviation; the deviation includes a deviation vector and a deviation value; The actual angular deviation is the angle between the error line and the horizontal or vertical direction; The actual line deviation is the product of the deviation value and the single-pixel resolution size of the camera; The adjustment recommendations provide an attitude adjustment scheme for the autocollimator based on the actual angular deviation and / or actual linear deviation.

2. The optical alignment verification system according to claim 1, characterized in that, Also includes: The verification process recording module is used to record deviations during the optical alignment verification process and the spot image after the optical alignment verification is completed, and to generate an alignment verification report.

3. The optical alignment verification system according to claim 1, characterized in that, The light source module is a laser or a structured light generator.

4. The optical alignment verification system according to claim 1, characterized in that, The camera is either a CCD camera or a CMOS camera.

5. An optical alignment verification method, implemented based on the optical alignment verification system according to any one of claims 1 to 4, characterized in that, Includes the following steps: S1: Slide the slider to position A near the end of the guide rail close to the light source module, and use the camera to capture the light spot image at this time as the first reference image; use an image processing algorithm to calculate the center coordinates of the light spot in the first reference image. ; S2: Slide the slider to position B, the end of the guide rail furthest from the light source module, and use the camera to capture the light spot image at this time as the second reference image; use an image processing algorithm to calculate the center coordinates of the light spot in the second reference image. ; S3: In the first reference image coordinate system, the center coordinates and Using the straight line segment formed as a baseline, calculate the coordinates of the theoretical center point M of the baseline. ; S4: Adjust the attitude of the autocollimator to position the measured light spot at the theoretical center point M, acquire the light spot image at this time, and obtain the center coordinates of the measured light spot in the light spot image. ; S5: Calculate the center coordinates The deviation from the theoretical center point M; if the deviation is not greater than the preset deviation threshold, the optical alignment verification is completed; if the deviation is greater than the preset deviation threshold, the attitude of the autocollimator is readjusted, and steps S4 to S5 are repeated.

6. The optical alignment verification method according to claim 5, characterized in that, In step S1 or step S2, the image processing algorithm is a brightness threshold segmentation combined with region analysis method.

7. The optical alignment verification method according to claim 5, characterized in that, In step S5, the deviation includes a deviation vector. and deviation values ; The deviation vector The calculation formula is: ； The deviation value The calculation formula is: 。

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