A method for processing measured surface data suitable for optical modeling

Abstract

This invention relates to the field of data processing technology, specifically providing a method for processing measured surface shape data suitable for optical modeling. The method involves acquiring measured surface shape data of the optical element under test using an interferometer, correcting its projection distortion, masking the measured surface shape data according to modeling requirements to remove unnecessary data, performing a precise coordinate transformation to convert the measured surface shape data from the detection coordinate system to the modeling system coordinate system, and finally correcting the data points and converting the data into a data format recognizable by the optical software used for modeling, before performing simulation modeling. This invention solves the problem of large errors when directly loading measured surface shape data into the optical model, effectively eliminating errors in the measured surface shape data and improving the accuracy of optical system performance simulation analysis.

Description

Technical Field

[0001] The present invention relates to the technical field of data processing, and in particular provides a method for processing measured surface shape data suitable for optical modeling. Background Art

[0002] As high-tech precision instruments, space optical payloads are crucial for ensuring reliable optical performance in the complex environment of space. Due to limitations in ground-based physical experimental conditions, some key optical performance tests cannot be conducted. The results of integrated simulation analysis serve as a valuable reference. Therefore, improving the accuracy of integrated simulation modeling is essential.

[0003] Optical system modeling is a key step in the integrated simulation and analysis of space optical payloads, and optical component surface data is one of the core data for optical system modeling. Due to factors such as errors in the optical component surface detection process and inconsistencies between the component detection coordinate system and the optical system coordinate system in the optical software, large errors can occur when directly loading measured optical component surface data into the optical model during optical modeling. To ensure that the optical model is closer to the actual optical system, it is crucial to process the measured surface data into surface data that is closer to the actual optical system and suitable for high-precision optical modeling. Summary of the Invention

[0004] In order to solve the above problems, the present invention provides a method for processing measured surface shape data suitable for optical modeling, which solves the problem of large errors when directly loading measured surface shape data into the optical model. The measured surface shape data is subjected to a series of data processing to eliminate errors in the optical element detection process. The measured surface shape data is converted into surface shape data suitable for high-precision optical modeling through processes such as converting the element detection coordinate system. This method can effectively improve the accuracy of optical system performance simulation analysis.

[0005] To achieve the above object, the technical solution created by the present invention is implemented as follows:

[0006] The present invention provides a method for processing measured surface shape data suitable for optical modeling, comprising:

[0007] S1: Provide the measured surface shape data of the optical element under inspection and perform projection distortion correction on the measured surface shape data;

[0008] S2: Mask the corrected measured surface data to extract the surface area required for modeling;

[0009] S3: Convert the masked measured surface data into the modeling system coordinate system;

[0010] S4: Visualize the measured surface data in the modeling system coordinate system, correct abnormal data points, and obtain surface data for optical modeling.

[0011] Preferably, an interferometer is used to collect the measured surface shape data of the optical element under inspection.

[0012] Preferably, the process of projective distortion correction is:

[0013] The measured surface shape data is projected and corrected based on the functional relationship between the surface coordinate system of the optical element under test and the detection coordinate system. The detection coordinate system is the corresponding coordinate system on the interferometer detection surface when the interferometer collects the measured surface shape data of the optical element under test.

[0014] Preferably, the surface shape of the optical element to be inspected is spherical or aspherical.

[0015] Preferably, when the surface shape of the optical element to be inspected is a spherical surface, the functional relationship between the surface coordinate system of the optical element to be inspected and the detection coordinate system is:

[0016] ;

[0017] in, is the radial coordinate on the surface of the optical element being inspected, is the radius of the optical element under inspection, is the radial coordinate measured by the interferometer, It is the focal length of the standard mirror used by the interferometer to collect the measured surface data of the optical component under test.

[0018] Preferably, when the surface shape of the optical element to be inspected is aspherical, a compensator is designed to perform zero-position interference detection on the optical element to be inspected during the process of collecting measured surface shape data by the interferometer, and multiple calibration target stickers are set on the surface of the optical element to be inspected. The detection coordinates of each calibration target sticker in the detection coordinate system are obtained from the measured surface shape data collected by the interferometer, and the functional relationship between the surface coordinate system of the optical element to be inspected and the detection coordinate system is constructed using the detection coordinates and the surface coordinates of each calibration target sticker in the surface coordinate system of the optical element to be inspected.

[0019] Preferably, the surface shape area required for modeling is the surface shape within the clear aperture of the optical element under inspection in the modeling system.

[0020] Preferably, S3, based on the coordinate conversion relationship between the surface coordinate system of the inspected optical element and the detection coordinate system, the masked measured surface shape data is converted to the surface coordinate system of the inspected optical element, and then the measured surface shape data in the surface coordinate system is converted to the modeling system coordinate system.

[0021] Preferably, the method for correcting abnormal data points includes: eliminating data points that deviate from a preset range through statistical analysis, then smoothing the measured surface data, and interpolating the missing data points.

[0022] Preferably, the method further includes S5: converting the measured surface shape data after the abnormal data points are corrected into a data format recognizable by the optical software used in modeling.

[0023] Compared with the prior art, the present invention can achieve the following beneficial effects:

[0024] This invention proposes for the first time to eliminate errors generated in the detection process of measured surface shape data. Through a series of projection distortion correction, mask processing, precise coordinate transformation and data point correction, the errors in the measured surface shape data are effectively eliminated, thereby improving the accuracy of optical system performance simulation analysis, helping to more accurately predict and evaluate the performance of optical systems in complex space environments, and thus providing a more reliable reference for the design and optimization of optical payloads.

[0025] The present invention performs high-precision coordinate transformation on the measured surface shape data, and finally converts the measured surface shape data obtained in the detection coordinate system into the modeling system coordinate system after processing, thereby achieving coordinate consistency for simulation in optical software and making the simulation model closer to the actual optical system.

[0026] In addition, the method of the present invention can be applied not only to spherical mirrors, but also to aspherical mirrors, especially free-form mirrors commonly used in optical systems. It has a wide range of applications, and the processing steps are clear. It is easy to program according to the steps to achieve automated processing, thereby improving the efficiency of data processing. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The accompanying drawings, which constitute part of the present invention, are intended to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are intended to explain the present invention and do not constitute an undue limitation of the present invention. In the accompanying drawings:

[0028] Figure 1 is a flow chart of processing measured surface shape data according to an embodiment of the present invention;

[0029] Figure 2 2 is a schematic diagram of an optical path for aspheric surface detection according to an embodiment of the present invention;

[0030] Figure 3 2. It is a schematic diagram of the target position of the mirror surface of the optical element to be inspected according to an embodiment of the present invention;

[0031] Figure 4 2. Schematic diagram of target position in an aspheric surface detection coordinate system according to an embodiment of the present invention;

[0032] Figure 5 is a schematic diagram of a circular aperture surface mask provided according to an embodiment of the present invention;

[0033] Figure 6 Schematic diagram of a rectangular aperture mask with chamfered corners provided according to an embodiment of the present invention;

[0034] Figure 7 is a schematic diagram of coordinate system conversion provided according to an embodiment of the present invention;

[0035] Figure 8 4 is a data point correction flow chart provided according to an embodiment of the present invention. DETAILED DESCRIPTION

[0036] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and do not constitute a limitation to the present invention. Similar elements in different embodiments use associated similar element numbers. In the following embodiments, many detailed descriptions are intended to enable the present invention to be better understood. However, those skilled in the art can easily recognize that some of the features can be omitted in different situations, or can be replaced by other elements, materials, or methods. In some cases, some operations related to the present invention are not shown or described in the specification. This is to avoid the core part of the present invention being overwhelmed by too much description. For those skilled in the art, it is not necessary to describe these related operations in detail. They can fully understand the related operations based on the description in the specification and the general technical knowledge in the art.

[0037] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments of the present invention can be combined with each other to form various implementation methods. At the same time, the steps or actions in the method description can also be interchanged or adjusted in a manner that is obvious to those skilled in the art. Therefore, the various orders in the description and the drawings are only for the purpose of clearly describing a certain embodiment and are not intended to be a required order, unless otherwise specified that a certain order must be followed.

[0038] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, features defined as "first", "second", etc. may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0039] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "installed," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to internal connections between two components. Those skilled in the art can understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0040] The present invention will be described in detail below with reference to the accompanying drawings and in combination with embodiments.

[0041] See also Figure 1 In one embodiment of the present invention, a method for processing measured surface shape data suitable for optical modeling is proposed, which specifically includes the following steps:

[0042] S1: For any optical component in the optical system to be optically modeled, the measured surface shape data of the optical component is detected using a common optical mirror surface shape measurement instrument such as an interferometer. Because the measured surface shape data directly measured by the interferometer has a unique format, this data generally requires specific software to view and process. If programming is required, this data must be converted into a data format that is easy to process and view for subsequent analysis and application.

[0043] In order to overcome the optical distortion generated when using an interferometer to detect the measured surface shape data of the optical element under test, the embodiment of the present invention needs to perform projection distortion correction on the measured surface shape data. Different correction methods need to be adopted according to the actual surface shape of the optical element under test. Specifically, the surface shape of the optical element under test is broadly divided into spherical and aspherical surfaces. Aspherical surfaces also include free-form surfaces commonly used in optical systems. In the embodiment of the present invention, the process of projection distortion correction is specifically given when the optical element under test is a spherical reflector and an aspherical reflector:

[0044] For spherical mirrors, there is a fixed functional relationship between the surface coordinate system of the optical element under inspection (or mirror coordinate system) and the detection coordinate system of the interferometer. The functional relationship is specifically:

[0045] ;

[0046] in, is the radial coordinate on the surface of the optical element being inspected, is the radius of the optical element under inspection, is the radial coordinate measured by the interferometer, It is the focal length of the standard mirror used by the interferometer to collect the measured surface data of the optical component under test.

[0047] It should be noted that the surface coordinate system of the optical element under test is established relative to the surface of the optical element under test, usually with the geometric center of the optical element as the origin. Each point on the surface of the optical element under test is assigned a coordinate based on its position relative to the origin, which reflects the surface shape of the mirror surface of the optical element under test in space. The detection coordinate system is established relative to the CCD detector in the interferometer, usually with the center of the detector as the origin. In the detection coordinate system of the interferometer, the surface of the optical element under test is mapped onto the target surface of the CCD detector, forming an interference pattern. The coordinates in this coordinate system reflect the position of the light reflected from the optical element under test on the CCD detector, so the detection coordinate system can also be called the CCD coordinate system.

[0048] The projection distortion of the measured surface shape data can be directly corrected according to the functional relationship between the surface coordinate system of the optical element under inspection and the detection coordinate system of the interferometer.

[0049] For aspheric mirrors, since their radius of curvature changes with the position of the mirror, please refer to Figure 2 When using interferometer to detect the surface shape, a compensator is required to perform zero-position interference detection. However, due to the design, manufacturing and assembly errors of the compensator, there is a more complex nonlinear relationship between the surface coordinate system of the optical element being tested and the detection coordinate system. Therefore, it is necessary to accurately calibrate it. For details, please refer to Figure 3During the surface shape detection process, it is necessary to attach multiple calibration target stickers to the surface of the optical component being inspected. The number and position of the calibration target stickers are determined by the complexity of the surface shape of the optical component being inspected. The surface coordinates (or mirror coordinates) of each calibration target sticker in the surface coordinate system of the optical component being inspected can be directly determined based on the attachment situation and can be considered as known quantities. In this embodiment of the present invention, five calibration target stickers are specifically provided. These five calibration target stickers are respectively in the surface coordinate system: Figure 3 in 、 、 、 and In addition, when the interferometer is used for surface shape detection, the coordinates of the five calibration targets in the detection coordinate system can also be obtained. The corresponding points of the calibration targets in the detection coordinate system are expressed as Figure 4 in 、 、 、 and The detection coordinates of these five calibration targets in the detection coordinate system and the mirror coordinates in the surface coordinate system can be used to obtain the functional relationship between the surface coordinate system of the optical element under test and the detection coordinate system of the interferometer. This coordinate system relationship is used to perform projection distortion correction on the measured surface data.

[0050] S2: During the processing of optical components, due to factors such as processing accuracy, error control, limitations of materials and processing technology, and optimization design of structural parameters, the processing aperture of the optical component is usually slightly larger than the design aperture value to ensure that the final performance and quality meet the expected standards. However, when performing optical modeling, it is generally only necessary to simulate the surface shape within the aperture or other data useful for modeling. However, the measured surface shape data collected by the interferometer includes these redundant surface shape data. Therefore, in the embodiment of the present invention, it is necessary to mask the corrected measured surface shape data, extract the surface shape area required for modeling, remove the redundant surface shape data, and only retain the measured surface shape data required for simulation. Please refer to Figure 5 and Figure 6 Taking the common circular aperture and the rectangular aperture with chamfered corners as examples, mask processing can be used to extract the data corresponding to the surface area required for modeling from the corrected measured surface data.

[0051] S3: In the above process, the measured surface shape data is always in the detection coordinate system of the interferometer, and the coordinates of the calibration target on the aspheric surface are in the surface coordinate system. When optically modeling the optical element to be tested, the data input into the optical modeling software should be in the modeling system coordinate system of the optical system where the optical element to be tested is located. Therefore, it is necessary to convert the masked measured surface shape data from the detection coordinate system to the modeling system coordinate system. For details, please refer to Figure 7 According to the coordinate transformation relationship between the surface coordinate system of the inspected optical element and the detection coordinate system, the masked measured surface shape data is transformed from the detection coordinate system to the surface coordinate system of the inspected optical element. Then, according to the optical path of the optical system to be modeled, the coordinate transformation relationship between the surface coordinate system of the inspected optical element and the optical system coordinate system is obtained. The measured surface shape data in the surface coordinate system is transformed into the modeling system coordinate system, and the coordinate inconsistency of the measured surface shape data in the optical software is corrected.

[0052] S4: Due to measurement errors and other factors, some invalid data points exist in the measured surface data, and the edge of the interference pattern has edge data points distorted due to diffraction effects, so further correction of the data points is required. Figure 8 First, use a visualization tool to view the measured surface data after coordinate conversion. Statistical analysis determines that data points that deviate from the preset range are invalid data points. The preset range can be manually set based on simulation accuracy. Identify outliers or erroneous data whose coordinates significantly deviate from the preset range and remove them. After removing these invalid data points, use a smoothing algorithm to smooth the data points. Available smoothing algorithms include, but are not limited to, moving averages and Gaussian filters, which can significantly reduce noise in the data. Furthermore, interpolation is required for the locations of missing or excluded outlier data points to fill in the data gaps. Finally, fine-tune the data in the local area based on the visualization data to correct errors within a small range.

[0053] S5: Before performing optical simulation modeling on the high-precision surface shape data obtained after the above processing, it is also necessary to convert its data format into a data format that can be recognized by the optical software used for modeling. Specifically, when the modeling software is ZEMAX software, it is necessary to convert the surface shape data that can be used for optical modeling into the ".dat" format; when the modeling software is CODEV software, it is necessary to convert the surface shape data that can be used for optical modeling into the ".int" format. After the format conversion is completed, the final surface shape data can be input into the modeling software for modeling. The present invention proposes for the first time a method for eliminating optical element detection errors in measured surface shape data, which significantly improves the accuracy of ground simulation modeling of space optical payloads, avoids the problem of the final modeling not being consistent with the actual optical performance of space optical payloads due to interferometer detection errors, and makes the optical model established by simulation closer to the actual optical system, laying a good foundation for subsequent model analysis and research.

[0054] In short, the above description is only a preferred embodiment of this specification and is not intended to limit the scope of protection of this specification. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of this specification shall be included in the scope of protection of this specification.

[0055] The systems, devices, modules, or units described in one or more of the above embodiments may be implemented by a computer chip or entity, or by a product having a certain function. A typical implementation device is a computer. Specifically, the computer may be, for example, a personal computer, a laptop computer, a cellular phone, a camera phone, a smartphone, a personal digital assistant, a media player, a navigation device, an email device, a game console, a tablet computer, a wearable device, or a combination of any of these devices.

[0056] It should also be noted that the terms "comprises," "includes," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, commodity, or apparatus that includes a series of elements includes not only those elements but also other elements not explicitly listed, or includes elements inherent to such process, method, commodity, or apparatus. In the absence of further limitations, an element defined by the phrase "comprises a ..." does not exclude the presence of other identical elements in the process, method, commodity, or apparatus that includes the element.

[0057] The various embodiments in this specification are described in a progressive manner. Similar parts between the various embodiments can be referred to in conjunction with each other. Each embodiment focuses on the differences between the other embodiments. In particular, the system embodiments are generally similar to the method embodiments, so the description is relatively simple. For relevant parts, refer to the description of the method embodiments.

[0058] The foregoing description of this specification describes specific embodiments. Other embodiments are within the scope of the appended claims. In some cases, the actions or steps recited in the claims can be performed in an order different from that described in the embodiments and still achieve the desired results. Furthermore, the processes depicted in the accompanying drawings do not necessarily require the specific order shown or the sequential order to achieve the desired results. In certain embodiments, multitasking and parallel processing are also possible or may be advantageous.

Claims

1. A method for processing measured surface data suitable for optical modeling, characterized in that: include: S1: Provide the measured surface shape data of the optical element under test, and perform projection distortion correction on the measured surface shape data; the process of projection distortion correction is as follows: Performing projection distortion correction on the measured surface shape data according to the functional relationship between the surface coordinate system of the optical element under test and the detection coordinate system, wherein the detection coordinate system is the corresponding coordinate system on the detection surface of the interferometer when the interferometer collects the measured surface shape data of the optical element under test; the surface shape of the optical element under test is spherical or aspherical; When the surface shape of the optical element to be inspected is a spherical surface, the functional relationship between the surface coordinate system of the optical element to be inspected and the detection coordinate system is: ； in, is the radial coordinate on the surface of the optical element under inspection, is the radius of the optical element under inspection, is the radial coordinate measured by the interferometer, The focal length of the standard mirror used by the interferometer to collect the measured surface data of the optical element under test; When the surface shape of the optical element to be inspected is aspherical, during the process of the interferometer collecting the measured surface shape data, a compensator is designed to perform zero-position interference detection on the optical element to be inspected, and a plurality of calibration targets are set on the surface of the optical element to be inspected, and the detection coordinates of each calibration target in the detection coordinate system are obtained from the measured surface shape data collected by the interferometer, and the functional relationship between the surface coordinate system of the optical element to be inspected and the detection coordinate system is constructed using the detection coordinates and the surface coordinates of each calibration target in the surface coordinate system of the optical element to be inspected; S2: Mask the corrected measured surface data to extract the surface area required for modeling; S3: Convert the masked measured surface data to the modeling system coordinate system; S4: Visualize the measured surface shape data in the modeling system coordinate system, correct abnormal data points, and obtain surface shape data for optical modeling.

2. The measured surface data processing method suitable for optical modeling according to claim 1, characterized in that: An interferometer is used to collect the measured surface shape data of the optical element under inspection.

3. The measured surface data processing method suitable for optical modeling according to claim 1, characterized in that: The surface shape area required for modeling is the surface shape within the light aperture of the optical element under inspection in the modeling system.

4. The method for processing measured surface shape data suitable for optical modeling according to claim 1, characterized in that: The S3 converts the masked measured surface shape data to the surface coordinate system of the optical element under inspection according to the coordinate conversion relationship between the surface coordinate system of the optical element under inspection and the detection coordinate system, and then converts the measured surface shape data in the surface coordinate system to the modeling system coordinate system.

5. The method for processing measured surface shape data suitable for optical modeling according to claim 1, characterized in that: The method for correcting abnormal data points includes: eliminating data points that deviate from a preset range through statistical analysis, then smoothing the measured surface data, and interpolating the missing data points.

6. The method for processing measured surface shape data suitable for optical modeling according to claim 1, characterized in that: The method further includes S5: converting the measured surface shape data after the abnormal data points are corrected into a data format recognizable by the optical software used in modeling.

Images