A method for controlling consistency between an actual optical system and simulation model parameters

Abstract

The present application relates to the technical field of optical engineering and digital twin cross, and specifically provides a practical optical system and simulation model parameter consistency control method, comprising: establishing a simulation model of a practical optical system, defining parameters of each element in the simulation model as variables, measuring parameter values of each element of the practical optical system and assigning values to the simulation model, obtaining simulation performance values of the simulation model and performance values of the practical optical system under the same conditions, and comparing to generate a performance consistency error report, determining potential error elements according to the performance consistency error report, and correcting errors through a virtual compensator and a phase plate to obtain a digital twin of the practical optical system. The present application systematically realizes correction of the simulation model and solves the problem of disconnection between the practical optical system and the simulation model.

Description

Technical Field

[0001] This invention belongs to the interdisciplinary field of optical engineering and digital twin technology, and in particular relates to a method for controlling the consistency of parameters between actual optical systems and simulation models. Background Technology

[0002] In optical system design and manufacturing, computer simulation is a crucial tool for predicting system performance and guiding design and tolerance allocation. However, due to uncertainties such as material parameter fluctuations, manufacturing errors, and assembly stress, the performance of the actually assembled optical system (“As-Built” system) often differs significantly from the predictions of the simulation model (“As-Designed” model). This discrepancy severely affects the reliability of simulation results, making simulation-based performance prediction, fault diagnosis, and system optimization difficult.

[0003] Existing technologies typically focus on improving the machining accuracy of individual components or performing simple model parameter replacements, lacking a systematic, closed-loop process to fundamentally bridge the gap between virtual simulation and real-world systems.

[0004] Therefore, there is an urgent need for a method that can dynamically and accurately control and maintain the consistency of parameters between the actual optical system and the simulation model. Summary of the Invention

[0005] In view of this, the present invention aims to provide a method for controlling the consistency of parameters between actual optical systems and simulation models. It establishes a closed-loop iterative process of "simulation-actual measurement-comparison-correction" and systematically and procedurally constructs a "digital twin" model that highly matches the state of the actual optical system, thus solving the problem of significant differences between traditional actual optical systems and simulation models.

[0006] To achieve the above objectives, the technical solution created by this invention is implemented as follows:

[0007] This invention provides a method for controlling the consistency of parameters between an actual optical system and a simulation model, comprising:

[0008] S1: Establish a simulation model of the actual optical system and define the parameters of each element in the simulation model as variables;

[0009] S2: Measure the parameter values ​​of each element in the actual optical system and the performance values ​​of the actual optical system; assign the parameter variables of each element in the simulation model to the parameter values ​​of each element in the actual optical system, and compare the simulation performance values ​​obtained by running the simulation model with the performance values ​​of the actual optical system to generate a performance consistency error report;

[0010] S3: Based on the performance consistency error report, identify the elements of potential errors and correct the simulation model using at least one of the following methods:

[0011] Method A: Introduce a virtual compensator into the simulation model. The virtual compensator takes minimizing the difference between the simulation performance value of the simulation model and the performance value of the actual optical system as the objective function, and iteratively obtains the optimal correction amount of the virtual compensator for each potential error element.

[0012] Method B: Introduce a phase plate into the simulation model and minimize the difference between the simulation performance value of the simulation model and the performance value of the actual optical system by optimizing the parameters of the phase plate;

[0013] S4: Use the modified simulation model as a digital twin of the actual optical system.

[0014] Preferably, S1 further includes: applying a perturbation to the simulation model, analyzing the sensitivity of the simulation model's performance values ​​to the parameter changes of each element, and generating a parameter sequence sorted by sensitivity.

[0015] Preferably, the sensitivity of the performance values ​​to changes in the parameters of each element is simulated using a Monte Carlo tolerance analysis simulation model.

[0016] Preferably, each element in the simulation model is an optical component, and the parameters of each element include curvature, thickness, position, attitude, and mechanical structure dimensions.

[0017] Preferably, the performance values ​​of the actual optical system and the simulation performance values ​​of the simulation model both include: wavefront aberration, modulation transfer function (MTF), and focal length.

[0018] Preferably, the correction includes: tilt, eccentricity, or Zernike polynomial coefficients characterizing surface shape error.

[0019] Preferably, the actual optical system and the simulation model operate under the same conditions, including the same test environment, wavelength, field of view, and aperture.

[0020] Preferably, step S3 further includes: after the simulation model is corrected, changing the operating conditions of the actual optical system and the simulation model, re-measuring the performance values ​​of the actual optical system and the simulation performance values ​​of the simulation model, and analyzing whether the difference between the performance values ​​and the simulation performance values ​​meets the preset tolerance. If the difference between the performance values ​​and the simulation performance values ​​is less than the preset tolerance, then step S4 is executed; if the difference between the performance values ​​and the simulation performance values ​​is greater than the preset tolerance, then step S3 is returned to be executed.

[0021] Compared with the prior art, the present invention can achieve the following beneficial effects:

[0022] This invention proposes a standardized closed-loop control process from pre-design to post-verification, completely changing the traditional fragmented and isolated calibration methods. This invention organically integrates simulation modeling, high-precision measurement, data comparison and analysis, intelligent model correction and verification, forming a sustainable iterative optimization system that systematically solves the fundamental problem of the disconnect between the actual system and the simulation model.

[0023] For the correction of the simulation model, this invention creatively introduces parametric correction methods such as virtual compensators and virtual phase plates, which can effectively capture and compensate for complex errors that are difficult to measure directly (such as assembly stress, unmodeled effects, etc.), greatly improving the prediction accuracy of the simulation model. Furthermore, the simulation model correction process incorporates verification and iteration steps to ensure that the simulation model can adaptively approximate the real state of the actual system. Attached Figure Description

[0024] 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:

[0025] Figure 1 This is an architecture diagram of a method for controlling the consistency of parameters between an actual optical system and a simulation model, provided by an embodiment of the present invention. Detailed Implementation

[0026] 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 only for explaining the invention and do not constitute a limitation thereof. Similar elements in different embodiments are referred to by associated similar element reference numerals. In the following embodiments, many details are described to facilitate a better understanding of the invention. However, those skilled in the art will readily recognize that some features may be omitted in different situations, or may be replaced by other elements, materials, or methods. In some cases, some operations related to the invention are not shown or described in the specification. This is to avoid obscuring the core parts of the invention with excessive description. For those skilled in the art, detailed description of these related operations is not necessary; the relevant operations can be fully understood based on the description in the specification and general technical knowledge in the art.

[0027] It should be noted that, unless otherwise specified, the embodiments and features described in this invention can be combined to form various implementations. Furthermore, the order of the steps or actions in the method description can be changed or adjusted in a manner readily apparent to those skilled in the art. Therefore, the various orders in the specification and drawings are merely for the clear description of a particular embodiment and do not imply a mandatory order, unless otherwise stated that a particular order must be followed.

[0028] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," 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.

[0029] 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.

[0030] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0031] Please see Figure 1 In one embodiment of the present invention, a method for controlling the consistency of parameters between an actual optical system and a simulation model is provided, comprising the following steps:

[0032] S1: Establish a simulation model of the actual optical system and define the parameters of each element in the simulation model as variables;

[0033] S2: Measure the parameter values ​​of each element in the actual optical system and the performance values ​​of the actual optical system; assign the parameter variables of each element in the simulation model to the parameter values ​​of each element in the actual optical system, and compare the simulation performance values ​​obtained by running the simulation model with the performance values ​​of the actual optical system to generate a performance consistency error report;

[0034] S3: Based on the performance consistency error report, identify the elements of potential errors and correct the simulation model using at least one of the following methods:

[0035] Method A: Introduce a virtual compensator into the simulation model. The virtual compensator adds a correction amount to each element of the potential error. The virtual compensator takes minimizing the difference between the simulation performance value of the simulation model and the performance value of the actual optical system as the objective function, and iteratively obtains the optimal correction amount for each element of the potential error.

[0036] Method B: Introduce a phase plate into the simulation model and minimize the difference between the simulation performance value of the simulation model and the performance value of the actual optical system by optimizing the parameters of the phase plate;

[0037] S4: Use the modified simulation model as a digital twin of the actual optical system.

[0038] Specifically, taking a high-resolution space remote sensing off-axis three-mirror optical system as an example, the process of obtaining a digital twin of the off-axis three-mirror optical system through a closed-loop iterative process of "simulation-measurement-comparison-correction" is as follows:

[0039] First, execute step S1 to perform the preliminary baseline establishment phase:

[0040] S101: Sensitivity Analysis of Simulation Model Parameters: A simulation model of an off-axis three-mirror optical system is established in optical simulation software. The simulation model includes three aspherical mirrors (primary mirror, secondary mirror, and tertiary mirror), all used off-axis. Further perturbations are applied to the simulation model. These perturbations involve changing the optical and mechanical parameters of some elements in the simulation model. The elements are the optical components of the simulation model, namely the primary mirror, secondary mirror, and tertiary mirror. The parameters of the elements are the optical parameters of the optical components and the mechanical dimensions, such as curvature, thickness, position, orientation, and mechanical dimensions. After applying the perturbations, the simulation model is run to obtain its simulation performance values. By comparing the fluctuations in the simulation performance values ​​before and after the perturbations, the sensitivity of the simulation model's performance values ​​to the parameter changes of each element can be analyzed. This also represents the degree of influence of parameter fluctuations on the performance values ​​of the actual optical system. A corresponding parameter sequence is generated based on the sensitivity of the simulation model's performance values ​​to the parameter changes of each element.

[0041] As an optional implementation, in studying the sensitivity of simulation model performance values ​​to parameter changes of each element, only a subset of performance indicators of interest can be selected to study the impact of parameter fluctuations on these key performance indicators, and the results can be presented as a parameter sequence sorted by sensitivity. Alternatively, in constructing the parameter sequence, only a subset of key parameters can be selected, while parameters whose changes have a relatively small impact on the simulation model's performance values ​​can be ignored.

[0042] As an optional implementation, the Monte Carlo tolerance analysis method is used in the sensitivity analysis process. First, the key performance indicators of interest are identified, specifically system image quality. Monte Carlo tolerance analysis yields the following key parameters highly sensitive to system image quality (especially wavefront error and full-field MTF): the displacement (ΔZ) of the secondary mirror along the optical axis and its tilt (Tx) around the X-axis, and the tilt (Ty) of the third mirror around the Y-axis. Simultaneously, the surface accuracy of each aspherical surface (represented by Zernike criterion terms) is identified as a highly sensitive key parameter. Subsequent optimization analysis primarily focuses on these highly sensitive key parameters; low-sensitivity parameters do not require optimization compensation. The highly sensitive key parameters vary depending on the performance indicator of interest, and the number of highly sensitive key parameters selected also varies depending on the accuracy requirements of the simulation model. Alternatively, all parameters of all elements can be used as key parameters for optimization analysis.

[0043] S102: Establish a standardized testing plan: To ensure the reliability of the optimization analysis and avoid interference from external factors, it is necessary to stipulate that the operating conditions of the actual optical system and the simulation model are exactly the same. That is, both need to be run under the same test environment, wavelength, field of view, and aperture to obtain the performance values ​​of the performance indicators of interest. Furthermore, it is necessary to stipulate that both use the same high-precision metrology equipment to obtain the performance values. For ease of distinction, the operating results of the simulation model are referred to as simulation performance values, and the operating results of the actual optical system are referred to as performance values. In this embodiment of the invention, it is stipulated that at a helium-neon laser wavelength of 632.8 nm, a long-stroke phase-shifting interferometer combined with a standard plane mirror / spherical mirror is used, and the full-aperture wavefront aberration is measured through sub-aperture stitching technology. The test environment is strictly controlled at a constant temperature of (20±0.5)°C.

[0044] S103: Constructing a parametric simulation model: Define the curvature, thickness, position, orientation, and mechanical structure dimensions of each optical element in the simulation model as variables to form a flexibly updatable parametric model. In this embodiment of the invention, the positions (X, Y, Z), orientations (Tx, Ty, Tz), and aspherical coefficients of the primary mirror, secondary mirror, and tertiary mirror are all set as variables to construct a complete parametric model, where Tx represents the tilt around the X-axis, Ty represents the tilt around the Y-axis, and Tz represents the tilt around the Z-axis.

[0045] Step S2 is executed to perform the data acquisition and comparison phase:

[0046] S201: First, the parameters of the actual optical system are measured. The parameter measurement stage is divided into component-level measurement and system-level measurement. Specifically, before the actual optical system is assembled, the "As-Built" parameter values ​​of each optical component of the actual optical system are measured, including the radius of curvature, center thickness, and refractive index. Specifically, only the key optical components in the parameter sequence can be measured. In this embodiment of the invention, before the actual optical system is assembled, a coordinate measuring machine (CMM) and a high-precision interferometer are used to measure the aspherical surface shapes of the primary mirror, secondary mirror, and third mirror (recorded in the form of Zernike coefficients), and the positions of their reference planes are recorded.

[0047] After the actual optical system is assembled, the "As-Built" performance values ​​of the actual optical system are measured, including wavefront aberration, modulation transfer function (MTF), and focal length. Specifically, after the actual optical system is assembled and coarsely adjusted, the actual wavefront aberration maps of the entire off-axis three-mirror system under different fields of view (such as 0 field of view, 0.7 field of view, and 1.0 field of view) are measured using a high-precision interferometer, i.e., the performance values.

[0048] S202: Perform the initial simulation-measurement comparison. Input the "As-Built" parameter values ​​of each optical element obtained from measurements before assembly of the actual optical system into the simulation model. Assign the parameter variables of each optical element in the simulation model to the parameter values ​​of each optical element in the actual optical system. At this time, the simulation model still uses the ideal position and orientation of the design. Run the simulation model under the same operating conditions as the actual optical system to obtain the simulated wavefront image, i.e., the simulated performance value. Compare the simulated wavefront image obtained from the simulation model with the actual wavefront aberration image of the actual optical system. Significant coma and astigmatism are found in the system, with a difference in wavefront error RMS value as high as 0.08λ (λ=632.8nm). A quantified performance consistency error report is generated accordingly.

[0049] Perform step S3 to conduct model analysis and correction:

[0050] S301: Perform root cause analysis of the discrepancies: Based on the performance consistency error report, identify the elements of potential errors and the specific parameters of these elements. In this embodiment of the invention, optical knowledge is used to confirm that coma and astigmatism are generally strongly correlated with the tilt and eccentricity of components, and it is confirmed that the discrepancies mainly originate from the minute pose errors generated during the assembly and adjustment of the secondary and tertiary mirrors, which exceed the accuracy range of CMM at the component level.

[0051] S302: Perform simulation model correction: Based on the elements of the potential errors identified above and their corresponding key parameters, correction is performed using method A and / or method B. In this embodiment of the invention, a strategy combining method B (introducing a virtual compensator) and method B (constructing a system-level equivalent model) is specifically adopted for correction.

[0052] First, the three most sensitive degrees of freedom for assembly and adjustment—ΔZ and Tx of the secondary mirror and Ty of the third mirror—are set as virtual compensators. Then, using the virtual compensators as optimization variables, correction amounts are added to the parameters of each potential error element. The objective function is to minimize the difference between the simulated performance value of the simulation model and the actual optical system performance value, i.e., to minimize the RMS value between the simulated and measured wavefronts. The simulation software is run to iteratively optimize the virtual compensators corresponding to the key parameters of each potential error element, thereby obtaining the optimal correction amounts for the key parameters of the potential error elements of the virtual compensators. For example, the secondary mirror needs to be compensated +5μm along the positive Z-axis and tilted -2.5 arcseconds around the X-axis. At this point, the poses of the optical elements in the simulation model are no longer ideal design values, but represent the "virtual optimal state" after system assembly and adjustment. After this round of correction, the RMS value of the wavefront difference is reduced to 0.02λ.

[0053] To further approximate the performance values ​​of the simulation model to those of the actual optical system, Method B is introduced. A virtual phase plate is added behind the primary mirror of the simulation model, and its surface shape is defined using the first 36 Zernike polynomials. These Zernike coefficients are optimized to minimize the difference between the simulated performance values ​​of the simulation model and the actual optical system's performance values ​​by optimizing the parameters of the phase plate, thus fitting the remaining aberrations. This compensates for complex factors such as the surface shape error of the primary mirror and surface shape changes introduced by mounting stress.

[0054] S303: Simulation Model Verification: Using the modified simulation model, perform performance tests on the simulation model and the actual optical system under another set of operating conditions. If the difference between the performance value and the simulated performance value under these operating conditions is less than the preset tolerance, then complete the model correction step S4; if the difference between the performance value and the simulated performance value is greater than the preset tolerance, return to step S3 for iterative correction. In this embodiment of the invention, the off-axis field of view of the actual optical system and the simulation model is changed to a -1.0 field of view, and the wavefront aberration and MTF of the actual optical system and the simulation model are obtained. A preset tolerance of 5% is set. Under the new operating conditions, the simulation performance value of the simulation model and the performance value of the actual optical system have a consistency of more than 95% (wavefront RMS difference < 0.01λ). The modified simulation model passes the verification, and its prediction accuracy is considered reliable.

[0055] Perform step S4 to complete the digital twin creation and application phase:

[0056] S401: Establish the digital twin model: The validated simulation model, which includes the optimal virtual compensator parameters and the equivalent phase plate Zernike coefficients, is identified as the "digital twin" of this specific off-axis three-mirror optical system.

[0057] S402: Process Standardization and Application: This digital twin can be used for:

[0058] Performance prediction: Accurately predict the imaging quality of this off-axis three-mirror optical system under different temperature conditions during on-orbit operation.

[0059] Fault diagnosis: If the performance of the actual optical system degrades during operation, the components that may have shifted can be quickly located by comparing the predictions of the "digital twin".

[0060] Guided reassembly and adjustment: Provides a more accurate compensation reference for the reassembly and adjustment of subsequent actual optical systems with the same design, shortening the reassembly and adjustment cycle.

[0061] In summary, the above description is merely a preferred embodiment of this specification and is not intended to limit the scope of protection of this specification. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this specification should be included within the scope of protection of this specification.

[0062] The systems, apparatuses, 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, a 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 any combination of these devices.

[0063] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0064] The various embodiments in this specification are described in a progressive manner. Similar or identical parts between embodiments can be referred to interchangeably. Each embodiment focuses on describing the differences from other embodiments. In particular, the system embodiments are basically similar to the method embodiments, so the description is relatively simple; relevant parts can be referred to the descriptions in the method embodiments.

Claims

1. A method for controlling the consistency of parameters between an actual optical system and a simulation model, characterized in that, include: S1: Establish a simulation model of the actual optical system, and define the parameters of each element in the simulation model as variables; S2: Measure the parameter values ​​of each element of the actual optical system and the performance value of the actual optical system; assign the parameter variables of each element in the simulation model to the parameter values ​​of each element of the actual optical system, and compare the simulation performance value obtained by running the simulation model with the performance value of the actual optical system to generate a performance consistency error report; S3: Based on the performance consistency error report, determine the elements of potential errors, and correct the simulation model using at least one of the following methods: Method A: Introduce a virtual compensator into the simulation model. The virtual compensator takes minimizing the difference between the simulation performance value of the simulation model and the performance value of the actual optical system as the objective function, and iteratively obtains the optimal correction amount of the virtual compensator for each potential error element. Method B: Introduce a phase plate into the simulation model, and minimize the difference between the simulation performance value of the simulation model and the performance value of the actual optical system by optimizing the parameters of the phase plate; S4: Use the modified simulation model as a digital twin of the actual optical system.

2. The method for controlling the consistency of parameters between the actual optical system and the simulation model according to claim 1, characterized in that, S1 further includes: applying a perturbation to the simulation model, analyzing the sensitivity of the simulation model's performance values ​​to changes in the parameters of each element, and generating a parameter sequence sorted by sensitivity.

3. The method for controlling the consistency of parameters between the actual optical system and the simulation model according to claim 2, characterized in that, The sensitivity of the simulation performance values ​​of the simulation model to changes in the parameters of each element was analyzed using Monte Carlo tolerance analysis.

4. The method for controlling the consistency of parameters between the actual optical system and the simulation model according to claim 1, characterized in that, Each element in the simulation model is an optical component, and the parameters of each element include curvature, thickness, position, orientation, and mechanical structure dimensions.

5. The method for controlling the consistency of parameters between the actual optical system and the simulation model according to claim 1, characterized in that, The performance values ​​of the actual optical system and the simulation performance values ​​of the simulation model both include: wavefront aberration, modulation transfer function (MTF), and focal length.

6. The method for controlling the consistency of parameters between the actual optical system and the simulation model according to claim 1, characterized in that, The corrections include: tilt, eccentricity, or Zernike polynomial coefficients characterizing surface shape errors.

7. The method for controlling the consistency of parameters between the actual optical system and the simulation model according to claim 1, characterized in that, The actual optical system and the simulation model operate under the same conditions, including the same test environment, wavelength, field of view, and aperture.

8. The method for controlling the consistency of parameters between the actual optical system and the simulation model according to claim 7, characterized in that, S3 further includes: after the simulation model is corrected, changing the operating conditions of the actual optical system and the simulation model, re-measuring the performance value of the actual optical system and the simulation performance value of the simulation model, and analyzing whether the difference between the performance value and the simulation performance value meets the preset tolerance. If the difference between the performance value and the simulation performance value is less than the preset tolerance, then S4 is executed; if the difference between the performance value and the simulation performance value is greater than the preset tolerance, then S3 is returned to be executed.

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