Method for analyzing scattering of ultra-high-speed impact on optical element based on finite element simulation

Abstract

The invention relates to the field of scattering analysis of optical elements, in particular to a scattering analysis method of ultra-high-speed impact on an optical element based on finite element simulation, which comprises the following steps of: respectively setting parameters of each impact object and a target plate in finite element simulation software, and constructing an impact object model and a target plate model; the impactor model and the target plate model form an ultra-high-speed impact model; performing ultra-high-speed impact simulation based on the ultra-high-speed impact model to obtain an impacted target plate model, and extracting three-dimensional shape data of each impact crater from the impacted target plate model; constructing an optical element model, importing the three-dimensional shape data of each impact crater into the optical element model, and obtaining the optical element model with a plurality of impact craters through data fitting; and calculating a bidirectional scattering distribution function according to each impact crater of the optical element model to obtain the influence of the scattering of the impact crater on the optical system. According to the invention, the influence of light scattering caused by the impact crater on the imaging quality can be analyzed.

Description

Technical Field

[0001] The present invention belongs to the technical field of scattering analysis of optical elements, and in particular relates to a scattering analysis method of an optical element caused by ultra-high-speed impact based on finite element simulation. Background Art

[0002] As human beings explore the universe, the size of spacecraft continues to expand, and the space exploration environment is becoming increasingly crowded. The existence of meteoroids and space debris has begun to affect the execution of space optical exploration missions. The dynamic effects of ultra-fast flight of meteoroids and space debris have a significant impact on the service life of spacecraft, which is a factor that must be considered in future space flights.

[0003] Micrometeoroids and space debris with a size less than 1 mm in the space environment are tiny particles in space. Space debris is usually some aluminum alloys and metal oxides such as zinc and titanium, with a density of 2.8g / cm 3 The average impact velocity is 10km / s, and the average impact velocity of micrometeoroids is even higher, reaching 20km / s. Optical devices are important payloads on spacecraft, such as solar spectroradiometers, solar observers, telescopes, optical remote sensors, etc. These optical devices play an important role in spacecraft navigation, communication, remote sensing, scientific experiments, etc. In the space environment, after the optical components of optical devices are hit by dust particles, dust pollution films or impact pits will form on their surfaces, which will affect the optical performance of the optical components. Although these effects will not lead to the overall failure of the optical device, the service life of the optical device will inevitably be affected. Therefore, the detection and control of surface defects of optical components is an important means to ensure the quality of optical components.

[0004] At present, dust particle accelerators, two-stage light gas guns and other devices are usually used to accelerate tiny particles to 1km / s-15km / s to achieve hypervelocity impact experiments on optical components. However, most of the experimental results are to study the morphology of the impact crater of the optical component after the hypervelocity impact, the splashes around the impact crater, and the changes in the film layer after the impact. The influence of light scattering caused by the impact crater on the imaging quality has not been studied. Summary of the invention

[0005] In view of this, the present invention aims to provide a scattering analysis method of ultra-high-speed impact on optical elements based on finite element simulation, so as to analyze the influence of light scattering caused by impact craters on imaging quality.

[0006] To achieve the above object, the technical solution created by the present invention is implemented as follows: A scattering analysis method of an optical element caused by a hypervelocity impact based on finite element simulation comprises the following steps: S1: setting the parameters of each impactor and target plate in the finite element simulation software, constructing the impactor model and the target plate model, which constitute the hypervelocity impact model; S2: Perform hypervelocity impact simulation based on the hypervelocity impact model to obtain a target plate model after impact, and extract the three-dimensional morphology data of each impact crater from the target plate model after impact; S3: construct an optical element model, and import the three-dimensional morphology data of each impact crater into the optical element model, and obtain an optical element model with multiple impact craters through data fitting; S4: Calculate the bidirectional scattering distribution function according to each impact crater of the optical element model to obtain the scattering characteristics of the optical element surface.

[0007] Furthermore, the parameters of the impactor include shape, density, size, impact velocity and impact angle, and the parameters of the target plate include thickness, size, material, density and Young's modulus.

[0008] Furthermore, the area of ​​the target plate is at least four times the diameter of the impactor, and the thickness of the target plate is at least five times the length of the impactor.

[0009] Furthermore, the bidirectional scattering distribution function The calculation formula is:

[0010] In the formula, is the diffuse differential radiance, is the incident differential irradiance, and are the elevation angle and azimuth angle of the incident light of the optical element, and are the elevation and azimuth angles of the scattered light from the optical element, is the differential incident luminous flux, is the azimuth, is the incident luminous flux.

[0011] Furthermore, the bidirectional scattering distribution function Including Bidirectional Reflectance Distribution Function , bidirectional reflectance distribution function The calculation formula is:

[0012] in, is the maximum elevation angle of light scattered by the optical element, is the minimum elevation angle of light scattered by the optical element, is the Harvey model scattering parameter in the maximum scattering direction, is the maximum difference between the projections of the unit vectors of the scattering direction and the specular reflection direction on the surface of the optical element, is the minimum difference between the projections of the unit vectors of the scattering direction and the mirror reflection direction on the surface of the optical element, and s is the spatial distribution characteristic of the scattered light.

[0013] Furthermore, the influence of the scattering characteristics of the optical element surface on the point spread function PSF is evaluated. The calculation formula of the point spread function PSF is:

[0014] in, is the radiance; γ is a constant; is the luminous flux reflected by the surface of the optical element.

[0015] Furthermore, the influence of the scattering characteristics of the optical element surface on the modulation transfer function MTF is evaluated. The calculation formula of the modulation transfer function MTF is:

[0016] in, and are the maximum and minimum grayscale values ​​of the image stripes, respectively.

[0017] Compared with the prior art, the invention can achieve the following beneficial effects: The present invention can utilize finite element simulation software to simulate the ultra-high-speed impact of tiny particles on optical elements, and analyze the influence of light scattering caused by impact craters on imaging quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The drawings constituting part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments and descriptions of the present invention are used to explain the present invention and do not constitute an improper limitation on the present invention. In the drawings: Figure 1 It is a flow chart of a method for analyzing the scattering of an optical element by a hypervelocity impact based on finite element simulation according to an embodiment of the invention; Figure 2 is a structural diagram of a hypervelocity impact model according to an embodiment of the invention; Figure 3 It is a structural diagram of the target plate model after impact according to the embodiment of the invention; Figure 4 It is a cloud map of a hypervelocity impact after being calculated by the SPH algorithm according to the embodiment of the invention; Figure 5 is a derived diagram of the target plate model according to the invention embodiment; Figure 6 It is a three-dimensional topographic image of the impact crater extracted from the target plate model according to the invention embodiment; Figure 7 It is a fitting diagram of the three-dimensional morphology of the impact crater and the optical element according to the embodiment of the invention; Figure 8 It is a bidirectional scattering distribution function diagram according to an embodiment of the present invention. DETAILED DESCRIPTION

[0019] In order to make the purpose, technical solution and advantages of the invention more clear, the 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 here are only used to explain the invention and do not constitute a limitation of the invention.

[0020] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0021] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" 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 technical features indicated. Thus, 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.

[0022] In the description of the invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installation", "connection" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the invention can be understood according to specific circumstances.

[0023] The present invention will be described in detail below with reference to the accompanying drawings and in combination with embodiments.

[0024] like Figure 1-Figure 8As shown, the present invention provides a method for analyzing the scattering of an optical element by a hypervelocity impact based on finite element simulation, comprising the following steps: S1: In the finite element simulation software, the parameters of each impactor and target plate are set respectively, and the impactor model and the target plate model are constructed. The impactor model and the target plate model constitute a hypervelocity impact model.

[0025] The finite element simulation software is ANSYS-LSDYNA. The hypervelocity impact model includes two parts: the impactor model and the target plate model. The impactor model is constructed by setting the shape, density, size, impact speed and impact angle of the impactor in the finite element simulation software. The target plate model is constructed by setting the thickness, size, material, density and Young's modulus of the target plate in the finite element simulation software. In order to prevent the impactor from penetrating the target plate and affecting the export of the impact result, the thickness of the target plate is set to at least five times the length of the impactor.

[0026] First, establish a coordinate system to facilitate setting position parameters. Then, construct an impactor through the FEM (finite element) plate and set the state equation of the impactor. Then, construct a single-layer target plate model and set the state equation of the single-layer target plate model.

[0027] S2: Perform hypervelocity impact simulation based on the hypervelocity impact model to obtain a target plate model after impact, and extract three-dimensional morphology data of each impact crater from the target plate model after impact.

[0028] The hypervelocity impact model is connected to the equation of state of the impactor model and the equation of state of the single-layer target plate model, and then the initial conditions are set, and then the hypervelocity impact simulation is performed. The size and impact velocity of the impactor are optimized, and the impact angle is changed at the same time. By changing the target plate material (using SiC and other materials) and the impactor material parameters (changing to ice and other material density parameters), the sensitivity of the hypervelocity impact model is analyzed using the control variable method. For example, the target plate is set to SiC material, and the physical parameters of the impactor are set to be consistent. First, the speed of the impactor is changed to a speed range of 3-10km / s, and the target plate damage morphology is observed; then the speed of the impactor is fixed, the geometric parameters of the impactor are modified, and the target plate damage morphology is observed; then the geometric parameters and speed of the impactor are fixed, and the impactor material is modified, and the target plate damage morphology is observed. Replace the target plate material and perform the above operations again to study the degree of damage to the target plate caused by the hypervelocity impact, so as to find suitable materials to extend the service life of optical components and reduce the impact effect.

[0029] After the target plate model is hit by a hypervelocity impact, sputtering will be formed around the impact crater. During the impact process, micro-explosion will occur due to the high speed, leaving parameters such as the impact stress on the target plate. A dynamic physical model is constructed by combining key parameters such as different impact angles, different impact speeds, different impact object sizes, and different target plate materials. The dynamic physical model is used to extract the deformation parameters of different impact results. The target plate data is processed and extracted using the post-processing algorithm of the finite element simulation software, and the three-dimensional morphology of the impact crater after the impact is extracted using the morphology extraction algorithm. The post-processing algorithm is an algorithm that comes with the finite element simulation software and is exportable data, such as stress and other parameters. The basic process of the morphology extraction algorithm is to import the deformation parameters of the impact result, filter the deformation data with abnormal values, and finally re-fit the filtered data to facilitate the subsequent combination of the impact result with the optical element model.

[0030] S3: Construct an optical element model and import the three-dimensional morphology data of each impact crater into the optical element model, and obtain an optical element model with multiple impact craters through data fitting.

[0031] The optical component model of the curved surface structure was constructed using ANSYS-ZEMAX software. The deformation data extracted by the morphology extraction algorithm was imported into the optical component model, and the three-dimensional morphology of the impact crater after the impact was extracted. It was precisely coupled with the constructed optical component model, and the impact crater formed by the impact was fitted on the surface, thus successfully constructing the optical component model after the hypervelocity impact. Subsequently, the precise setting of the material and grid of the curved surface was completed, and the model after the three-dimensional morphology of the impact crater and the optical component model were successfully constructed, such as Figure 7 shown.

[0032] Based on the above-constructed three-dimensional morphology of the impact crater and the model fitted with the optical element model, different illumination sources are set according to different impact craters. For example, for tiny impact craters, a light source with high illumination intensity is needed to analyze the scattered light. Parallel light is needed to analyze the overall scattered light. The analysis of the impact crater position requires ray tracing, adding a geometric optical interface, and analyzing the shape and position of the impact crater based on ray tracing. This ray tracing method can intuitively observe the scattering effect caused by the impact crater, analyze the location of the impact crater, and facilitate the search for stray light at the image plane position. Set a detector on the image plane to facilitate the observation of changes in the physical field and the impact of scattering caused by the impact crater.

[0033] S4: Calculate the bidirectional scattering distribution function according to each impact crater of the optical element model to obtain the scattering characteristics of the optical element surface.

[0034] For the scattered light analyzed by the optical software, the image plane stray light data is analyzed, and the irradiance is normalized to obtain the impact of the impact crater on the optical system, so as to facilitate the evaluation of the impact of the scattering caused by the impact crater on the image contrast, PSF, and MTF. With the help of the physical field diagram generated by the detector, the scattered light spots caused by the impact crater are observed, and the changes in the mirror focal length and field of view caused by the impact crater are observed.

[0035] PSF describes the response of an optical system to a point light source and determines the resolution and clarity of the imaging system. In a scattering medium, the scattering of light will cause the expansion and deformation of the PSF, thus affecting the imaging quality. The narrower the PSF, the stronger the imaging system's ability to resolve close point light sources and the higher the imaging quality.

[0036] Image contrast refers to the measurement of the different brightness levels between the brightest white area and the darkest black area in an image, that is, the magnitude of the grayscale contrast of an image. The larger the difference range, the greater the contrast, and the smaller the difference range, the smaller the contrast.

[0037] Example 1 For micrometeoroids in space, their density is uncertain. The density of micrometeoroids is not calculated by fixed statistical methods, but is obtained by observations of scientific technologies such as radar. From radar observations, we know that the density of micrometeoroids ranges from about 0.16g / cm 3 To 4g / cm 3 However, there are great differences in the average mass density values ​​from different literatures. Generally speaking, 0.5 g / cm 3 As a baseline for estimation, the mass-density relationship is (1); Where m is the mass of the micrometeoroid in g. In the study of the impact of small debris on the EURECA and HST solar panels, the diameter of the shell-shaped fragmentation zone of the impact crater was defined as ), target density ( )、Particle density( ), particle diameter ( ), and the particle velocity ( ) and a series of characteristic parameters such as particle impact angle (θ).

[0038] (2); The uniformity and standardization of these characteristic parameters make them an important basis and reference for subsequent ground simulation studies of impact crater characteristics. Figure 2 The figure shows the model diagram of the hypervelocity impact. The geometric parameters of the model are constructed based on the input parameters. The impactor has a diameter of 100 μm, a length of 50 μm, and a density of 2.8 g / cm3 The target plate has a geometrical parameter of 800μm×800μm×400μm. After correction, the empirical formula with the impact angle is: (3); in, is the central crater diameter.

[0039] Deriving ballistic limits in spatial data The expression is: (4).

[0040] Ballistic Limit Used for calculation of the impact process, mainly the impact on the diameter of the impact crater, is the yield strength of the target plate, is the density of the target plate. Combining formula (1) and formula (4), we can get the ballistic limit and the diameter of the shell-shaped fragmentation zone of the impact crater The relationship expression is given by experience, and the proportional factor is given by experience, as shown in the following formula: (5); (6).

[0041] in, Represents the volume of the impacting particle. The proportional factor is related to the diameter of the fragmentation zone and is an experience summarized from a large amount of experimental data. In addition to the impact of the defects of the impact crater itself, factors such as cracks around the crater will also affect the scattering. Therefore, the proportional factor belongs to the maximum range of calculation and mainly has an impact during the impact process.

[0042] This is a damage assessment method that reveals the impact of relevant parameters on the impact crater. Figure 3 As shown in the figure, the maximum diameter of the defect pit on the target plate after the impact is about 4 times the size of the impacting object. For multi-particle groups in the space environment, a flux model is usually used to describe them. Flux is a physical quantity that represents the number of objects that impact a unit area of ​​the spacecraft surface per unit time in a certain space. The micrometeoroid environment flux model is a commonly used model at present. Its advantages are simple calculation and wide application range. The expression of the micrometeoroid environment flux model gives the total average meteoroid flux in an integral form, that is, the number of impacting particles with a mass greater than or equal to a given mass m per square meter per year.

[0043] Without considering the Earth's shielding and gravity effects, the flux of the micrometeoroid environment flux model is omnidirectional, that is, no matter what the position and direction of the spacecraft is, it will be hit by meteoroids from all directions. The micrometeoroid environment flux model is applicable to a mass of 10 -18For meteoroids with a mass of more or less, other models are needed for calculation. Figure 4 The figure shows the cloud map of the hypervelocity impact after the SPH algorithm calculation. According to the micrometeoroid environment flux model, the flux of meteoroids can be expressed as: (7); in, The mass is greater than 10 -9 The particle flux of g, The mass is greater than 10 -14 g is less than 10 -9 The particle flux of g, The mass is less than 10 -14 g particle flux;

[0044] (8).

[0045]

[0046] The micrometeoroid environment flux model is widely used in the risk assessment of spacecraft in the Earth-Moon orbit. The current simulation results show that the maximum impact crater diameter is 4 times the diameter of the impact object, which is consistent with theoretical research. Figure 5 As shown in the figure, it is the geometric model derived diagram of the target plate after impact. Figure 6 is the curve surface morphology extracted by the algorithm. The extracted three-dimensional morphology and the mirror surface are fitted to obtain Figure 7 Defect and mirror fit diagram shown.

[0047] The bidirectional scattering distribution function (BSDF) uses a geometric calculation method to characterize the spatial scattering characteristics of a surface. This definition shows that the ratio of the scattered radiance to the incident irradiance at a point on the surface is an important parameter for measuring the spatial scattering characteristics of a surface at a certain point. The theoretical calculation of BSDF is derived from the geometric optics model. The significance of this model lies in that it can not only be measured and fitted through experiments, but also the BSDF value can be calculated and analyzed theoretically to understand and quantify the scattering characteristics of the optical surface.

[0048] (9); in, is the diffuse differential radiance, is the incident differential irradiance, and are the elevation angle and azimuth angle of the incident light of the optical element, and are the elevation and azimuth angles of the light scattered by the optical element, respectively.

[0049] is the differential incident luminous flux, written as the differential scattered luminous flux per differential projection solid angle ( , representing stray light) is differentiated by the incident light flux ( )The normalized result: (10).

[0050] For optical elements such as mirrors, more attention is paid to the bidirectional reflectance distribution function (BRDF). Figure 8 As shown, BRDF and BTDF (bidirectional transmission distribution function, BTDF is to illustrate that the BSDF studied in the present invention is composed of BRDF and BTDF. In this embodiment, the optical element hit is a reflector, so BSDF mainly contains reflected light and does not contain transmitted light. Therefore, there is no need to calculate BTDF) are both important components of BSDF. The BRDF expression in the modified ABg model is: (11); in, is the maximum elevation angle of light scattered by the optical element, is the minimum elevation angle of light scattered by the optical element, is the Harvey model scattering parameter in the maximum scattering direction, is the difference between the projections of the unit vectors of the scattering direction and the specular reflection direction on the surface of the optical element, is the maximum value of the difference, is the minimum value of the difference, and s is the spatial distribution characteristic of the scattered light.

[0051] When the incident angle is fixed, the light flux is redistributed based on the BRDF distribution (scattering component). Therefore, when the incident angle and other conditions remain unchanged, the equation can be simplified to: (12); Among them, C is the simplified constant term coefficient, is the azimuth angle of the scattered light projected on the XOY plane, is the incident wavelength, and There are two micro-surfaces, representing tiny area units.

[0052] The optical transfer function OTF of a linear invariant optical system can be expressed as: (13); in, is the exit pupil coordinate of the optical system, is the pupil function of the optical system, is the position on the pupil plane The complex conjugate of the pupil function at , represents displacement, Displacement vector in the pupil plane.

[0053] The purpose of calculating the optical transfer function OTF is to solve the PSF. The Fourier transform of the PSF intensity is the optical transfer function OTF.

[0054] According to Huygens superposition principle, the light field distribution on the reflecting hemispherical surface can be expressed as: (14); in, are direction cosines, j is an imaginary number, is the exit pupil coordinate of the optical system, γ is a constant used to normalize or adjust the magnitude of the function, is the initial pupil function of the optical system, and F is the Fourier transform symbol.

[0055] When the optical element is a reflector, the luminous flux reflected by the reflector surface can be expressed in the form of an integral: (15); According to the law of radiation propagation in optics: (16); in, is the radiant brightness, is the solid angle.

[0056] Combining formula (15) and (16), we can get: (17); For a hemispherical receiving surface, the PSF can be calculated by the following formula: (18).

[0057] When light passes through a scattering medium (such as biological tissue, haze, etc.), the information of the original object will be disrupted, and the shape and width of the PSF will be affected by the scattering characteristics. This effect makes it challenging for the imaging system to restore the target image, especially in a high-scattering environment, where changes in the PSF will significantly reduce the clarity and contrast of the image. Therefore, the PSF itself can represent the impact of scattering on imaging quality.

[0058] For MTF, the calculation formula is as follows: (19); in, and are the maximum and minimum grayscale values ​​of the image stripes, respectively.

[0059] In this way, the scattering effect of optical component damage caused by micrometeoroid hypervelocity impacts can be evaluated. The complexity of the space environment has a huge impact on aerospace missions. If it can be verified and a solution can be proposed in ground experiments, or the influence of stray light caused by micrometeoroid impacts can be eliminated, the processed results will be more accurate. There are many studies on hypervelocity impacts in traditional research, but there is no research on the effect of light scattering caused by impact craters on the imaging quality of optical systems. This method simulates hypervelocity impacts based on finite element simulation, extracts the three-dimensional morphology of the impact crater from the impact target surface, fits the three-dimensional morphology of the impact crater with the optical element, and performs multi-physics field coupling simulation, and finally derives the effect of hypervelocity impacts on the scattering of optical elements.

[0060] In summary, this method can be used to evaluate the damage to optical components caused by hypervelocity impacts of micrometeoroids and space debris in the space environment, such as evaluating the impact of physical damage caused by hypervelocity impacts on the service life of optical components, and evaluating the impact of scattered light caused by defects in the mirror due to the impact event on the imaging quality of the optical system. It can also be used to detect the surface roughness of optical components. These simulations provide guidance for the protection of space telescopes, the evaluation of imaging quality, and an in-depth understanding of the optical and mechanical properties of materials, and provide guidance for the development of new materials and the improvement of existing materials. 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 recorded in the disclosure of the present invention can be executed in parallel, sequentially, or in different orders, as long as the desired results of the technical solution disclosed in the present invention can be achieved, and this document is not limited here.

[0061] The above specific implementations do not constitute a limitation on the protection scope of the present invention. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent substitution and improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A scattering analysis method for optical elements caused by hypervelocity impact based on finite element simulation, characterized in that: The steps include: S1: setting the parameters of each impactor and target plate in the finite element simulation software, constructing the impactor model and the target plate model, which constitute the hypervelocity impact model; S2: Perform hypervelocity impact simulation based on the hypervelocity impact model to obtain a target plate model after impact, and extract the three-dimensional morphology data of each impact crater from the target plate model after impact; S3: construct an optical element model, and import the three-dimensional morphology data of each impact crater into the optical element model, and obtain an optical element model with multiple impact craters through data fitting; S4: Calculate the bidirectional scattering distribution function according to each impact crater of the optical element model to obtain the scattering characteristics of the optical element surface.

2. The method for analyzing the scattering of an optical element by a hypervelocity impact based on finite element simulation according to claim 1, characterized in that: The parameters of the impactor include shape, density, size, impact velocity and impact angle, and the parameters of the target include thickness, size, material, density and Young's modulus.

3. The method for analyzing the scattering of optical elements by hypervelocity impact based on finite element simulation according to claim 2, characterized in that: The area of ​​the target plate is at least four times the diameter of the impactor, and the thickness of the target plate is at least five times the length of the impactor.

4. The method for analyzing the scattering of optical elements by hypervelocity impact based on finite element simulation according to claim 1, characterized in that: Bidirectional scattering distribution function The calculation formula is: In the formula, is the diffuse differential radiance, is the incident differential irradiance, and are the elevation angle and azimuth angle of the incident light of the optical element, and are the elevation and azimuth angles of the scattered light from the optical element, is the differential incident luminous flux, is the azimuth, is the incident luminous flux.

5. The method for analyzing the scattering of optical elements by hypervelocity impact based on finite element simulation according to claim 4, characterized in that: Bidirectional scattering distribution function Including Bidirectional Reflectance Distribution Function , bidirectional reflectance distribution function The calculation formula is: in, is the maximum elevation angle of light scattered by the optical element, is the minimum elevation angle of light scattered by the optical element, is the Harvey model scattering parameter in the maximum scattering direction, is the maximum difference between the projections of the unit vectors of the scattering direction and the specular reflection direction on the surface of the optical element, is the minimum difference between the projections of the unit vectors of the scattering direction and the mirror reflection direction on the surface of the optical element, and s is the spatial distribution characteristic of the scattered light.

6. The method for analyzing the scattering of optical elements by hypervelocity impact based on finite element simulation according to claim 1, characterized in that: The influence on the point spread function PSF is evaluated based on the scattering characteristics of the optical element surface. The calculation formula of the point spread function PSF is: in, is the radiance; γ is a constant; is the luminous flux reflected by the surface of the optical element.

7. The method for analyzing the scattering of optical elements by hypervelocity impact based on finite element simulation according to claim 1, characterized in that: The influence of the scattering characteristics of the optical element surface on the modulation transfer function MTF is evaluated. The calculation formula of the modulation transfer function MTF is: in, and are the maximum and minimum grayscale values ​​of the image stripes, respectively.

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