Internal stray light multi-physical field simulation method, device, equipment and medium

Abstract

The invention relates to computer simulation, and discloses an internal stray light multi-physical field simulation method, device and equipment and a medium. The method comprises the following steps: generating a to-be-tested system model according to assembly data of an actual mechanical model; dividing grids for each structural surface of the to-be-tested system model, and performing finite element analysis solution according to thermal characteristics, stress characteristics, boundary conditions and loads to obtain a final refractive index steady-state value, a temperature field steady-state model and a deformation stress model; importing the temperature field steady-state model and the deformation stress model into ray tracing software; light rays are reversely emitted from imaging surfaces of the thermal field steady-state model and the deformation stress model through light ray tracing software, and a key optical surface is screened through reverse light ray tracing; and carrying out sampling processing on the key optical surface by adopting forward ray tracing, and carrying out forward ray tracing on the temperature field steady-state model and the deformation stress model so as to obtain an internal stray light simulation result and a path analysis result. Therefore, the accuracy of internal stray light analysis is improved.

Description

Technical Field

[0001] The present application relates to the field of computer simulation, and in particular to a method, device, equipment and medium for simulating multi-physics fields of internal stray light. Background Art

[0002] From the perspective of research mechanism, there are two methods for studying the spontaneous heat radiation of the system: one is the BAT (built-and-test) method, which is to first manufacture a prototype and then use a measurement system to measure the level of stray radiation of the system. The other is the software modeling analysis method, which is to use large-scale analysis software to perform stray radiation simulation test analysis on the system. From the perspective of research methods, the analysis methods of spontaneous heat radiation include the Monte Carlo method, the ray tracing method, and the regional method. In the prior art, a complete simulation method for internal stray light has not yet been formed, and the prior art cannot be transplanted into the analysis of internal stray light. There is no simulation method that can include all the factors affecting internal stray light. Summary of the invention

[0003] In a first aspect, the present invention provides a multi-physics field simulation method for internal stray light, comprising: Generate a system model to be tested based on assembly data of the actual mechanical model; Defining thermal characteristics, stress characteristics, boundary conditions and loads of the system to be tested model; Divide the meshes for each structural surface of the system model to be tested, perform finite element analysis and solve according to the thermal characteristics, the stress characteristics, the boundary conditions and the loads, and obtain the temperature field steady-state model, the final refractive index steady-state value and the deformation stress model corresponding to the system model to be tested; Importing the temperature field steady-state model and the deformation stress model into ray tracing software, and using the ray tracing software to correspond the temperature field steady-state model to each structural surface of the deformation stress model; Defining the scattering characteristics and radiation characteristics of the system to be tested model; Reversely emitting light from the imaging surfaces of the temperature field steady-state model and the deformation stress model through the ray tracing software, and using reverse ray tracing to screen key optical surfaces based on the final refractive index steady-state value, the scattering characteristics, and the radiation characteristics; The key optical surface is sampled and processed by the ray tracing software, and forward ray tracing is performed on the temperature field steady-state model and the deformation stress model to obtain internal stray light simulation results and path analysis results based on the final refractive index steady-state value, the scattering characteristics and the radiation characteristics.

[0004] In an optional embodiment, the actual mechanical model includes an active device, and the system model to be measured includes an internal heat source model corresponding to the active device; The thermal properties include thermal conductivity, thermal expansion, thermal stability and heat capacity; the stress properties include elastic properties and expansion coefficient; The thermal characteristics and stress characteristics of the system model to be tested are the same as the thermal characteristics and stress characteristics of the actual mechanical model; the thermal characteristics and stress characteristics of the system model to be tested are defined by using a nonlinear model; The boundary conditions include the environmental conditions of the system model under test during operation; the load includes a linear model or a nonlinear model corresponding to the external environmental changes; The scattering properties include anisotropic scattering properties; The method further comprises: The contact type of each structural component of the system model to be tested is defined.

[0005] In an optional implementation, a finite element analysis is performed based on the thermal characteristics, the stress characteristics, the boundary conditions and the load to obtain a temperature field steady-state model corresponding to the system model to be tested, including: Finite element analysis is performed based on the thermal characteristics, the boundary conditions and the loads to determine the temperature change data of each grid on each structural surface and the temperature influence between each grid. The temperature change amount of each structural component is determined based on the temperature change data of each grid on each structural surface and the temperature influence between each grid to obtain the steady-state model of the temperature field.

[0006] In an optional implementation, a finite element analysis is performed based on the thermal characteristics, the stress characteristics, the boundary conditions and the load to obtain a deformation stress model corresponding to the system model to be tested, including: Obtain the relationship between the mechanical deformation and temperature of each structural component in the linear direction; According to the temperature variation of each structural component, the stress characteristics, and the relationship between the mechanical deformation and the temperature, a finite element analysis is performed to obtain the deformation stress model.

[0007] In an optional implementation, performing finite element analysis and solving according to the thermal characteristics, the stress characteristics, the boundary conditions and the load to obtain a final steady-state value of the refractive index corresponding to the system model to be tested includes: Obtain the relationship between the refractive index and temperature of each structural surface; According to the temperature variation of each structural surface and the relationship between the refractive index and the temperature, a finite element analysis is performed to obtain the final steady-state value of the refractive index.

[0008] In an optional embodiment, the method comprises: The relationship between the mechanical deformation and temperature of each structural component in the linear direction is determined according to the following formula 1: Formula 1: ΔL = αLΔt Wherein, ΔL represents the linear deformation of each structural part, L represents the size of each structural part in the linear deformation direction, α represents the linear expansion coefficient of each structural part, and Δt represents the temperature change of each structural body; The relationship between the refractive index and temperature of each structural surface is determined according to the following formula 2; Formula 2: n(T)=n0+dn / dT·(T−T0) Wherein, T represents the current temperature, T0 represents the reference temperature, n(T) represents the refractive index at the current temperature T, n0 represents the refractive index at the reference temperature T0, and dn / dT is the rate of change of the refractive index with temperature.

[0009] In an optional embodiment, the forward ray tracing of the temperature field steady-state model and the deformation stress model to obtain the internal stray light simulation result and the path analysis result based on the final refractive index steady-state value, the scattering characteristics and the radiation characteristics includes: The Monte Carlo method is used to calculate the radiation emittance of each structural surface at the corresponding final steady-state temperature, and the imaging surface stray light energy beam, imaging surface irradiance and imaging surface stray light incidence table are calculated.

[0010] In a second aspect, the present invention provides an internal stray light multi-physics field simulation device, comprising: A generation module, used for generating a model of the system to be tested according to the assembly data of the actual mechanical model; A first definition module is used to define the thermal characteristics, stress characteristics, boundary conditions and loads of the system to be tested model; A processing module, used for dividing a grid for each structural surface of the system model to be tested, performing finite element analysis and solving according to the thermal characteristics, the stress characteristics, the boundary conditions and the load, to obtain a temperature field steady-state model, a final refractive index steady-state value and a deformation stress model corresponding to the system model to be tested; An import module, used for importing the temperature field steady-state model and the deformation stress model into a ray tracing software, and making the temperature field steady-state model correspond to each structural surface of the deformation stress model through the ray tracing software; A second definition module is used to define the scattering characteristics and radiation characteristics of the system model to be tested; A screening module, configured to emit light in reverse from the imaging surfaces of the temperature field steady-state model and the deformation stress model through the ray tracing software, and screen key optical surfaces based on the final refractive index steady-state value, the scattering characteristics, and the radiation characteristics by using reverse ray tracing; An acquisition module is used to sample the key optical surface through the ray tracing software, and perform forward ray tracing on the temperature field steady-state model and the deformation stress model to obtain internal stray light simulation results and path analysis results based on the final refractive index steady-state value, the scattering characteristics and the radiation characteristics.

[0011] In a third aspect, the present invention provides a computer device, comprising a processor and a memory, wherein the memory stores a computer program, and the processor is used to execute the computer program to implement the internal stray light multi-physics field simulation method described in any one of the aforementioned embodiments.

[0012] In a fourth aspect, the present invention provides a computer storage medium storing a computer program, which, when executed on a processor, implements the internal stray light multi-physics field simulation method according to any one of the aforementioned embodiments.

[0013] The internal stray light multi-physics field simulation method provided by the present application generates a system model to be tested according to the assembly data of the actual mechanical model; defines the thermal characteristics, stress characteristics, boundary conditions and loads of the system model to be tested; divides the grid for each structural surface of the system model to be tested, performs finite element analysis and solves according to the thermal characteristics, the stress characteristics, the boundary conditions and the loads, and obtains the temperature field steady-state model, the final refractive index steady-state value and the deformation stress model corresponding to the system model to be tested; imports the temperature field steady-state model and the deformation stress model into the ray tracing software, and compares the temperature field steady-state model with the deformation stress model through the ray tracing software. The method corresponds to each structural surface of the stress model; defines the scattering characteristics and radiation characteristics of the system model to be tested; uses the ray tracing software to emit light in reverse from the imaging surface of the temperature field steady-state model and the deformation stress model, and uses reverse ray tracing to screen key optical surfaces based on the final steady-state value of the refractive index, the scattering characteristics, and the radiation characteristics; uses the ray tracing software to sample the key optical surfaces, and performs forward ray tracing on the temperature field steady-state model and the deformation stress model to obtain internal stray light simulation results and path analysis results based on the final steady-state value of the refractive index, the scattering characteristics, and the radiation characteristics. In this way, the temperature field, an important influencing factor of the internal stray light, is introduced into the stray light simulation by using multi-physical field simulation, and finally realizes the internal stray light analysis method coupled with multi-physical fields, thereby improving the accuracy of stray light analysis. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In order to more clearly illustrate the technical solution of the present application, the following is a brief introduction to the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present application and should not be regarded as limiting the scope of protection of the present application. For ordinary technicians in this field, other related drawings can also be obtained based on these drawings without creative work.

[0015] Figure 1 A schematic diagram of a process of a multi-physics field simulation method for internal stray light provided in an embodiment of the present application is shown; Figure 2 A structural schematic diagram of an internal stray light multi-physics field simulation device provided in an embodiment of the present application is shown.

[0016] Icon: 200 - internal stray light multi-physics field simulation device; generation module-201; first definition module-202; processing module-203; import module-204; second definition module-205; screening module-206; acquisition module-207. DETAILED DESCRIPTION

[0017] The technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments.

[0018] The components of the embodiments of the present application generally described and shown in the drawings herein may be arranged and designed in various configurations. Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the application claimed for protection, but merely represents the selected embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without making creative work belong to the scope of protection of the present application.

[0019] Hereinafter, the terms "including", "having" and their cognates, which may be used in various embodiments of the present application, are intended only to indicate specific features, numbers, steps, operations, elements, components, or combinations of the foregoing items, and should not be understood as first excluding the existence of one or more other features, numbers, steps, operations, elements, components, or combinations of the foregoing items or adding the possibility of one or more features, numbers, steps, operations, elements, components, or combinations of the foregoing items.

[0020] Furthermore, the terms “first”, “second”, “third”, etc. are merely used for distinguishing descriptions and are not to be understood as indicating or implying relative importance.

[0021] Unless otherwise defined, all terms (including technical terms and scientific terms) used herein have the same meanings as those generally understood by those skilled in the art to which the various embodiments of the present application belong. The terms (such as those defined in generally used dictionaries) will be interpreted as having the same meanings as the contextual meanings in the relevant technical field and will not be interpreted as having idealized meanings or overly formal meanings unless clearly defined in the various embodiments of the present application.

[0022] The comparison of the characteristics of existing BAT methods and software model simulations is shown in Table 1.

[0023] Table 1. Comparison of the characteristics of BAT method and software model simulation

[0024] As can be seen from the above table, when using large-scale analysis software to simulate and analyze the detection system, if the system parameters input during modeling can be guaranteed to be accurate enough, then its disadvantages can be ignored, and its advantages are very obvious. Especially for the stray radiation analysis of infrared detection systems, it is difficult to use the BAT experimental test method, and the error is also large. The software model simulation method can not only save the trouble of system modification, but also accurately and carefully analyze the stray radiation when the system works in the infrared band, and the impact on system components can also be analyzed separately. Therefore, the current estimation and evaluation of stray radiation of infrared systems is mainly based on software simulation calculation and analysis.

[0025] The following is an introduction to the Monte Carlo method, ray tracing method and regional method. The Monte Carlo method (Monte-Carlo Method or MCM) is a computer simulation method that uses random variables for statistics and was developed with the advent of computers. It was first used in the study of atomic bombs. Howell applied this method to the calculation of radiation heat transfer. He regarded the emission, reflection, transmission, scattering and absorption processes in the transmission of radiation energy as independent of each other, and then established a probability model related to the surface characteristics for each sub-process. Each unit emits a certain number of energy beams, and each energy beam is traced until the termination condition is met. The destination of each energy beam is counted to obtain the statistical results of the radiation energy distribution of this unit.

[0026] The ray tracing method uses a certain formula instead of a statistical method to analyze and calculate stray light. This method was developed on the following two foundations: first, the emergence of different ray tracing programs makes it easy to obtain the path of weighted light through the optical system; second, for the diffraction phenomenon, due to the development of scalar diffraction theory, it can be described by the propagation law of light emitted from the edge of the aperture. As for the calculation of the reflection part, it is carried out by determining the area of ​​the critical surface step by step. The surface that the receiver can see directly or indirectly in the optical system is called the critical surface. If the part that can be seen directly is called the first-level critical surface, the part that can be seen indirectly is the second-level or above critical surface. By solving the critical surface area, illuminance and diffuse reflection coefficient step by step, the stray radiation generated by diffuse reflection can be calculated. The intersection of the light after passing through the optical system and the receiving surface is represented by a point diagram. Each point on the diagram represents a portion of light energy. By calculating the weighted number of points per unit area, the illuminance generated by the imaging and non-imaging beams can be obtained. Obviously, if you want to obtain higher accuracy, you need to calculate more points.

[0027] The regional method, also known as the finite element method, is the same as the ray tracing method. It is also a deterministic method for calculating stray radiation. The regional method is based on the energy transfer equation to calculate stray light. It divides the structural surfaces of the system into many small areas, and calculates the direct transmission of radiation between each two areas, so as to obtain the transmission process of radiation energy in the entire system and the energy that finally reaches the image plane. The calculation accuracy of this method depends on the number of small areas divided. The part that contributes more to stray light should be divided more finely. When using this method to calculate stray light, in order to increase the calculation speed and avoid unnecessary calculations, the main paths of stray light transmission should be predicted first, and then the stray radiation levels at different off-axis angles should be calculated along these paths.

[0028] Compared with the Monte Carlo method, the regional method does not need to trace a large number of rays, but it needs to calculate a large amount of regional energy transfer, and the possible paths of stray light transmission must be determined in advance, otherwise it will add a lot of unnecessary calculations, which will seriously affect the speed. The difference between the ray tracing method and the Monte Carlo method is that the ray tracing method uses a certain formula instead of the traditional method to calculate stray light. It is very similar to the regional method and is also a deterministic calculation method. The difference is that the ray tracing method uses the method of geometric optics calculation to calculate the transmission of light.

[0029] In summary, in the prior art, a complete simulation method for internal stray light has not yet been formed, and the prior art cannot be transplanted into the internal stray light analysis, and there is no simulation method that can include all the factors affecting the internal stray light.

[0030] In conjunction with the accompanying drawings, some embodiments of the present application are described in detail below. In the absence of conflict, the following embodiments and features in the embodiments can be combined with each other.

[0031] This embodiment provides a multi-physics field simulation method for internal stray light, which fills the gap in internal stray light simulation and calculation, realizes comprehensive and efficient full-link simulation, and improves the accuracy of internal stray light simulation analysis.

[0032] See also Figure 1 The internal stray light multi-physics field simulation method provided in this embodiment includes steps S101-S107, and each step is described below.

[0033] Step S101 : generating a system model to be tested according to assembly data of an actual mechanical model.

[0034] In this embodiment, the internal stray light multi-physics field simulation method is applicable to various actual mechanical models that need to analyze internal self-heating radiation stray light. For example, the actual mechanical model can be an optical system with active devices. In particular, the actual mechanical model includes active devices, which can generate heat or cool, and the active devices include heating components. The system model to be tested includes an internal heat source model corresponding to the active device. For example, the system model to be tested operates in the thermal infrared band, and contains active devices inside, and there is a self-heating source inside the system. The system model to be tested needs to be consistent with the actual mechanical model, especially the shape, position, connection, etc. of the active device need to be consistent. For the active, its heating power and the main location of the heating of this active device need to be accurately calculated. The heating power can generally be referred to its user manual. The main heating location is related to the type of active device, such as the heating location of the switching power supply is the capacitor and relay, and the heating location of the spectroscopic crystal is the transducer.

[0035] It should be noted that, in the present embodiment, the internal stray light mainly considers the thermal infrared band, namely the medium-wave infrared and the long-wave infrared. External stray light is caused by other light sources, and internal stray light is caused by the actual mechanical model itself. The actual mechanical model can be an optical system, which is not limited here. The simulation method in the prior art is for external stray light analysis, so there is no need to consider temperature changes. It is only necessary to accurately establish the stress changes of the mechanical structure and the model of the mechanical structure to complete the external stray light simulation. However, the internal stray light is closely related to the temperature, and it is necessary to consider the changes in the ambient temperature during the operation of the overall system and the possible heating of active devices and other factors. Therefore, it is impossible to use the existing external stray light simulation scheme to simulate the internal stray light of the mechanical system.

[0036] It is further explained that the internal stray light multi-physics field simulation method also includes: The contact type of each structural component of the system model to be tested is defined.

[0037] It can be understood that due to the existence of the self-heating source inside the system, the heat source will transfer its own heat to all the surrounding contacting parts through heat conduction during actual operation, thereby affecting the overall temperature. After the overall temperature changes, it will also undergo heat convection in the air with the surrounding ambient temperature, and thermal radiation heat transfer will also occur between all the components in the overall system. Therefore, it is necessary to additionally define the contact type of each structural component of the system, and this definition is strongly related to the conduction of the self-heating source. Among them, the structural components can be understood as the components of the optical system.

[0038] Furthermore, in systems with active devices, the heat transfer method is very complex compared to other types of systems, and the heat transfer result is a very uneven temperature field. The temperature difference between the maximum and minimum temperatures in the system may differ by tens or even hundreds of degrees Celsius. If the traditional external stray light analysis method is used, the system is considered to be a system with uniform and stable temperature distribution, and accordingly no heat exchange and thermal deformation will occur, which will not affect the overall transmission efficiency of the optical path and the stray light transmission path. Therefore, for internal stray light, especially internal stray light containing active devices, it is necessary to introduce multi-physics field simulation, including mechanical deformation, temperature, stress, optics and other multi-physics field simulations, and accurately calculate the mutual influence factors of different physical fields and introduce them into the simulation of each physical field.

[0039] S102, defining the thermal characteristics, stress characteristics, boundary conditions and loads of the system model to be tested.

[0040] In this embodiment, the thermal characteristics include characteristics such as thermal conductivity, thermal expansion, thermal stability and heat capacity. The stress characteristics include characteristics such as elastic characteristics and expansion coefficient. After the simulation of the thermal characteristics of the material takes effect and is solved, each structural component of the actual mechanical model will produce temperature changes and deformations according to its own thermal characteristics and stress characteristics. The thermal characteristics and stress characteristics of the system model to be tested are the same as the thermal characteristics and stress characteristics of the actual mechanical model; the thermal characteristics and stress characteristics of the system model to be tested are defined using a nonlinear model. The thermal characteristics and stress characteristics of the system model to be tested are defined as corresponding nonlinear models according to the actual thermal characteristics and stress characteristics of the actual mechanical model.

[0041] In this embodiment, the boundary conditions include the environmental conditions of the system model under test during operation; the environmental conditions include environmental temperature, environmental convection characteristics, and environmental pressure, etc. For example, the environmental conditions of the system model under test are: placed in an ultra-clean laboratory with a constant temperature of 22° C., and the environment is a standard atmospheric pressure without wind.

[0042] The load includes a linear model or a nonlinear model corresponding to the external environment change. The load is the static load and the dynamic load of the system model to be tested. Specifically, according to the external environment change of the system model to be tested, the load is defined as a linear model or a nonlinear model, and the linear model or the nonlinear model of the load is consistent with the external environment change.

[0043] Among them, static load can be understood as a constant. For example, there is a heat source in an optical system. This heat source has a fixed power. The fixed power of the heat source is the static load. Dynamic load refers to the quantity that changes over time, such as the changing room temperature. For example, the load is a lighting fixture. For the lighting fixture, if the power and light intensity can be kept constant, it is a static load. If this heat source is still in an unstable stage, the power and light intensity are dynamically changing, which is a dynamic load.

[0044] S103, meshing each structural surface of the system model to be tested, performing finite element analysis and solving according to the thermal characteristics, the stress characteristics, the boundary conditions and the loads, and obtaining a final refractive index steady-state value, a temperature field steady-state model and a deformation stress model corresponding to the system model to be tested.

[0045] In this embodiment, combined with the interaction between multiple physical fields, modeling and calculation are performed for multiple physical fields, and then the influence of each physical field on the internal stray light is accurately calculated, thereby improving the accuracy of subsequent stray light analysis. It should be noted that the number of grid divisions is related to the simulation tool. The more grids there are, the more accurate the solution results are, but it has an impact on the operating efficiency of the computer. Among them, the temperature field steady-state model is the overall temperature distribution result after the final system is stabilized. This result can be expressed as a cloud map or as temperature data of several grid points, which is not limited here.

[0046] In this embodiment, the main optical axis of the system model to be tested is perpendicular to the surface of each structural part (component), and the temperature field steady-state model can be referenced by setting the average temperature value of each divided surface. If the system model to be tested is an optical system, the main optical axis refers to the optical direction of the optical system, such as the optical axis direction of a lens set in the Z direction is the X-axis direction or the Y-axis direction. The components are all optical elements in the optical system.

[0047] It should be further added that when dividing the grid for analysis, the number of grids on each surface is specific, and the thermal radiation value of each surface can be the integral of the grids with non-uniform temperature, or it can be solved directly with the average temperature. In other words, the temperature field steady-state model can be referenced by setting the average temperature value of each divided surface, or by the integral of the grids with non-uniform temperature.

[0048] In one embodiment, a finite element analysis is performed based on the thermal characteristics, the stress characteristics, the boundary conditions and the load to obtain a temperature field steady-state model corresponding to the system model to be tested, including: Finite element analysis is performed based on the thermal characteristics, the boundary conditions and the loads to determine the temperature change data of each grid on each structural surface and the temperature influence between each grid. The temperature change amount of each structural component is determined based on the temperature change data of each grid on each structural surface and the temperature influence between each grid to obtain the steady-state model of the temperature field.

[0049] For example, a structural surface has 100 grids, among which the temperature of the first grid is 10°C and the temperature of the second grid is 20°C. Then the temperatures of the first grid and the second grid will have a gradual change process. The mutual influence between the two grids during the temperature gradient process can be called the temperature mutual influence between the grids.

[0050] Exemplarily, the average temperature value of each surface of the system model to be tested is derived one by one through finite element analysis, and then input into the temperature definition of each surface to obtain a temperature field steady-state model.

[0051] In one embodiment, a finite element analysis is performed based on the thermal characteristics, the stress characteristics, the boundary conditions and the load to obtain a deformation stress model corresponding to the system model to be tested, including: Obtain the relationship between the mechanical deformation and temperature of each structural component in the linear direction; According to the temperature variation of each structural component, the stress characteristics, and the relationship between the mechanical deformation and the temperature, a finite element analysis is performed to obtain the deformation stress model.

[0052] In one embodiment, the internal stray light multi-physics field simulation method further includes: The relationship between the mechanical deformation and temperature of each structural component in the linear direction is determined according to the following formula 1: Formula 1: ΔL = αLΔt ΔL represents the linear deformation of each structural part, L represents the size of each structural part in the linear deformation direction (mm), α represents the linear expansion coefficient of each structural part ( / °C), and the expansion coefficient has different values ​​due to different materials. As long as the temperature change is not particularly large, it can be considered that for a certain material, α is a constant. For systems with large ambient temperature changes or active devices, there is a rated change relationship curve between α and temperature, which is related to the characteristics of the material itself. The expansion coefficient is one of the stress characteristics. Δt represents the temperature change of each structure (°C). The temperature change of each structure is one of the thermal characteristics.

[0053] In this embodiment, the linear changes of the structural parts in various directions can be accurately calculated by the finite element method, and then the overall deformation amount and deformation results in the 360° spherical space can be calculated. Exemplarily, a program code is set, which includes the correlation formulas about all thermal characteristics, the stress characteristics, the boundary conditions and the loads, and the finite element solution is used to divide the solution object into very small n grids, and then the deformation results inside the n grids and the deformation influence results between the n grids are solved respectively, and finally the overall deformation amount and deformation results are obtained, and the deformation stress model is obtained.

[0054] In one embodiment, a finite element analysis is performed based on the thermal characteristics, the stress characteristics, the boundary conditions and the load to obtain a final steady-state value of the refractive index corresponding to the system model to be tested, including: Obtain the relationship between the refractive index and temperature of each structural surface; According to the temperature variation of each structural surface and the relationship between the refractive index and the temperature, a finite element analysis is performed to obtain the final steady-state value of the refractive index.

[0055] It should be noted that the impact of mechanical deformation on light transmission is very intuitive. Light transmission follows the laws of refraction and reflection, etc. Therefore, any slight deformation will cause the angle of light transmission to change, thereby affecting the capture of effective light signals and the generation of stray light in the system. By calculating the structure after mechanical deformation, the idealization error of the model in the subsequent Monte Carlo calculation is avoided. Through the solution calculation of the above steps, the mechanical structure model after deformation stabilization is used to calculate the actual light transmission result, which effectively reduces the stress error in the final result.

[0056] It is understood that the influence of temperature on optical elements mainly includes refractive index and thermal expansion. The relationship between temperature and refractive index is not a simple formula relationship, but usually manifests as a complex nonlinear relationship. However, within a certain temperature range and for specific materials, an approximate linear relationship can be found to express the change of refractive index with temperature. It is understood that when the mechanical shape of the optical element changes and the temperature of the optical element changes, the refractive index of the optical element will change accordingly. First, the deformation and temperature change of the optical element are calculated by finite element method, so as to obtain the corresponding refractive index change.

[0057] In one embodiment, the internal stray light multi-physics field simulation method further includes: The relationship between the refractive index and temperature of each structural surface is determined according to the following formula 2; Formula 2: n(T)=n0+dn / dT·(T−T0) Where T represents the current temperature, T0 represents the reference temperature, n(T) represents the refractive index at the current temperature T, n0 represents the refractive index at the reference temperature T0, and dn / dT is the rate of change of the refractive index with temperature, also known as the temperature coefficient of the refractive index. The refractive index is one of the stress characteristics. Formula 2 assumes that near temperature T0, the change of the refractive index with temperature is linear, that is, the rate of change dn / dT is a constant.

[0058] By calculating the refractive index after temperature change, the idealization error of material parameters in the subsequent Monte Carlo calculation is avoided. Through the solution calculation of the aforementioned steps, the refractive index parameters after temperature stabilization are used to calculate the actual light transmission results, which effectively reduces the temperature error in the final result.

[0059] S104, importing the temperature field steady-state model and the deformation stress model into ray tracing software, and using the ray tracing software to correspond the temperature field steady-state model to each structural surface of the deformation stress model.

[0060] In this embodiment, the ray tracing software may use TRACEPRO, which is an optical simulation software commonly used for lighting systems, optical analysis, radiometric analysis, and photometric analysis. The deformation stress model and the temperature field steady-state model are imported into the TRACEPRO software, and the temperature field steady-state model is matched to each structural surface of the deformation stress model, and the imaging surface stray light data is calculated. The ray tracing software uses the Monte Carlo analysis method to calculate the imaging surface stray light data in the deformation stress model.

[0061] Exemplarily, the temperature field steady-state model is specifically the steady-state temperature data of each finite element analysis point. According to the mechanism of thermal radiation on the surface of an object, after experiments, for a small optical system in a laboratory, the average temperature of each structural surface can be used as the thermal radiation temperature benchmark of the entire surface. For large space-based systems or remote sensing systems, each surface needs to be divided into regions according to the temperature distribution of the heating surface, and then the average temperature distribution of each sub-region is calculated. The above-calculated surface average temperature can be directly used in the surface radiation characteristic setting, material refractive index and other parameter design and other temperature-related parameter settings in the ray tracing software. The radiation emittance of each surface is proportional to the temperature. The higher the temperature, the more radiation is emitted and the greater the thermal radiation stray light. The deformation and temperature change of the model system to be tested occur simultaneously, and the calculated surface average temperature is the final surface average temperature.

[0062] S105, defining the scattering characteristics and radiation characteristics of the system model to be tested.

[0063] In this embodiment, the scattering characteristics include anisotropic scattering characteristics. The ray tracing threshold is set by a computer, and the radiation characteristics refer to the characteristics of the component itself. Among them, the emissivity is approximately linearly related to the temperature. The smaller the ray tracing threshold, the higher the accuracy of the reverse ray tracing or forward ray tracing solution. For example, the ray tracing threshold is set to 0.00005. Among them, the radiation characteristics are strongly correlated with the deformation stress model, that is, the deformation of the deformation stress model has a great influence on the radiation characteristics.

[0064] It should be noted that the radiation emittance of the stray light radiated by the self-heating of an object refers to the sum of the energy of electromagnetic waves of various wavelengths emitted from the unit area of ​​the surface of the object per unit time. M It can be deduced from Planck's law that at wavelength and temperature T Under certain conditions, the relationship between blackbody radiation emittance, wavelength and temperature is expressed as follows: Formula 3:

[0065] Where c1 is the first radiation constant 3.7418×10 -16 W•m 2 , c2 is the second radiation constant 1.4388×10 -2 mK.

[0066] In addition, the Stefan-Boltzmann law describes the relationship between the radiant emittance of an object and its absolute temperature, as shown in the following formula 4: Formula 4:

[0067] In the formula, The value is 5.670373×10 -12 W cm -2 ·K -4 , called the Stefan-Boltzmann constant. From the above formula, we can see that the radiation emittance of an object is proportional to the fourth power of the temperature.

[0068] According to Formula 3 and Formula 4, the higher the temperature, the greater the radiation emission, and the greater the self-heating radiation stray light flux emitted by each structural component. In the stray light calculation process, the Monte Carlo method can be used to accurately calculate the radiation emission flux of the structural component at a specific temperature, and then calculate the radiation transmission result in the 360° spherical space. By calculating the radiation emission after temperature change, the idealization error of material parameters in the subsequent Monte Carlo calculation is avoided, and the temperature error is effectively reduced in the final result.

[0069] S106, emitting light in reverse from the imaging surfaces of the temperature field steady-state model and the deformation stress model through the ray tracing software, and using reverse ray tracing to screen key optical surfaces based on the final steady-state value of the refractive index, the scattering characteristics, and the radiation characteristics.

[0070] In this embodiment, the key surface refers to any surface that can be seen from the imaging plane, including the image plane of any surface that can be seen from surface reflection and system transmission, so it needs to be found by reverse light path tracing.

[0071] S107, sampling the key optical surface through the ray tracing software, performing forward ray tracing on the temperature field steady-state model and the deformation stress model, so as to obtain internal stray light simulation results and path analysis results based on the final refractive index steady-state value, the scattering characteristics and the radiation characteristics.

[0072] In this embodiment, the key optical surface is sampled, that is, the weight of the key optical surface is set, and the weight of the key optical surface is increased, so that in the forward ray tracing calculation process of the temperature field steady-state model and the deformation stress model, the weight of the key optical surface is larger, which can improve the accuracy of the forward ray tracing calculation results. The calculation process of forward ray tracing can adopt the Monte Carlo method, the ultimate goal of which is to obtain the stray light data on the imaging surface of the system model to be tested, and the indirect goal is to solve the transmission path and transmission data of the stray light from each source.

[0073] It is understandable that temperature will affect the radiation emittance, which in turn directly affects the internal stray light simulation results. Deformation will affect the light propagation path, which will also directly affect the internal stray light simulation results. The parameters of optical components will change with temperature and deformation, which will in turn affect the light transmission efficiency and the path analysis results.

[0074] In this embodiment, the internal stray light simulation result includes an imaging surface irradiance and an imaging surface stray light incidence table.

[0075] In this way, the critical optical surfaces are renovated for ray tracing, improving tracing efficiency and accuracy.

[0076] It is understandable that most of the existing technologies simulate the stray light outside the field of view (i.e., external stray light), but lack accurate calculation of internal stray light (i.e., system self-heating stray light). By adopting the internal stray light multi-physics field simulation method provided in this embodiment, quantitative calculation of internal stray light can be achieved. When simulating stray light outside the field of view, the existing technology only considers the stress field as the other physical field, and does not consider the influence of other physical fields such as temperature field on the overall structure of the system to be measured, the optical path, etc. The multi-physics field simulation method for internal stray light provided in this embodiment, combined with the use of multi-physics field simulation, introduces the important influencing factors of internal stray light, such as temperature field and refractive index change, into the stray light simulation, and finally realizes the internal stray light analysis method coupled with multiple physical fields, thereby improving the accurate analysis of internal stray light.

[0077] In one embodiment, the forward ray tracing of the temperature field steady-state model and the deformation stress model to obtain internal stray light simulation results and path analysis results based on the final refractive index steady-state value, the scattering characteristics, and the radiation characteristics includes: The Monte Carlo method is used to calculate the radiation emittance of each structural surface at the corresponding final steady-state temperature, and the imaging surface stray light energy beam, imaging surface irradiance and imaging surface stray light incidence table are calculated.

[0078] In this embodiment, the influencing factors of internal stray light are calculated and integrated, and through the fusion simulation of multiple physical fields, combined with the actual operating environment and scenario, accurate system internal stray light values ​​and optical paths are calculated, which has guiding significance for subsequent system optical analysis and correction.

[0079] This embodiment also provides a multi-physics field simulation device for internal stray light. Figure 2 The internal stray light multi-physics field simulation device 200 comprises: A generation module 201 is used to generate a system model to be tested according to assembly data of an actual mechanical model; A first definition module 202, used to define the thermal characteristics, stress characteristics, boundary conditions and loads of the system model to be tested; The processing module 203 is used to divide the grids for each structural surface of the system model to be tested, and perform finite element analysis and solution according to the thermal characteristics, the stress characteristics, the boundary conditions and the loads to obtain a temperature field steady-state model, a final refractive index steady-state value and a deformation stress model corresponding to the system model to be tested; An import module 204 is used to import the temperature field steady-state model and the deformation stress model into a ray tracing software, and correspond the temperature field steady-state model to each structural surface of the deformation stress model through the ray tracing software; A second definition module 205, used to define the scattering characteristics and radiation characteristics of the system model to be tested; A screening module 206 is used to reversely emit light from the imaging surface of the temperature field steady-state model and the deformation stress model through the ray tracing software, and use reverse ray tracing to screen key optical surfaces based on the final refractive index steady-state value, the scattering characteristics and the radiation characteristics; The acquisition module 207 is used to sample the key optical surface through the ray tracing software, and perform forward ray tracing on the temperature field steady-state model and the deformation stress model to obtain the internal stray light simulation results and path analysis results based on the final refractive index steady-state value, the scattering characteristics and the radiation characteristics.

[0080] It can be understood that the internal stray light multi-physics field simulation device of this embodiment corresponds to the internal stray light multi-physics field simulation method of the above embodiment, and the options in the above embodiment are also applicable to this embodiment, so they will not be repeated here.

[0081] The present application also provides a computer device. Exemplarily, the computer device includes a processor and a memory, wherein the memory stores a computer program, and the processor runs the computer program to enable the computer device to execute the functions of each module in the above-mentioned internal stray light multi-physics field simulation method or the above-mentioned internal stray light multi-physics field simulation device.

[0082] Among them, the processor can be an integrated circuit chip with signal processing capabilities. The processor can be a general-purpose processor, including a central processing unit (CPU), a graphics processing unit (GPU), a network processor (NP), a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field programmable gate array (FPGA) or at least one of other programmable logic devices, discrete gates or transistor logic devices, and discrete hardware components. The general-purpose processor can be a microprocessor or the processor can also be any conventional processor, etc., which can implement or execute the methods, steps and logic block diagrams disclosed in the embodiments of the present application.

[0083] The memory may be, but is not limited to, a random access memory (RAM), a read only memory (ROM), a programmable read-only memory (PROM), an erasable programmable read-only memory (EPROM), an electric erasable programmable read-only memory (EEPROM), etc. The memory is used to store a computer program, and the processor may execute the computer program accordingly after receiving an execution instruction.

[0084] The present application also provides a computer storage medium for storing the computer program used in the above-mentioned computer device. The computer storage medium may be a readable storage medium, or a non-volatile storage medium or a volatile storage medium. For example, the computer storage medium may include but is not limited to: a USB flash drive, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk or an optical disk, and other media that can store program codes.

[0085] In several embodiments provided in the present application, it should be understood that the disclosed devices and methods can also be implemented in other ways. The device embodiments described above are merely schematic. For example, the flowcharts and structure diagrams in the accompanying drawings show the possible architecture, functions and operations of the devices, methods and computer program products according to multiple embodiments of the present application. In this regard, each box in the flowchart or block diagram can represent a module, a program segment or a part of a code, and the module, a program segment or a part of a code contains one or more executable instructions for implementing the specified logical function. It should also be noted that in an alternative implementation, the functions marked in the box can also occur in a different order from the order marked in the accompanying drawings. For example, two consecutive boxes can actually be executed substantially in parallel, and they can sometimes be executed in the opposite order, depending on the functions involved. It should also be noted that each box in the structure diagram and / or the flow diagram, and the combination of boxes in the structure diagram and / or the flow diagram, can be implemented with a dedicated hardware-based system that performs a specified function or action, or can be implemented with a combination of dedicated hardware and computer instructions.

[0086] In addition, the functional modules or units in the various embodiments of the present application may be integrated together to form an independent part, or each module may exist separately, or two or more modules may be integrated to form an independent part.

[0087] If the functions are implemented in the form of software function modules and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present application, or the part that contributes to the prior art, or the part of the technical solution, can be embodied in the form of a software product, which is stored in a storage medium and includes several instructions for enabling a computer device (which can be a smart phone, a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present application.

[0088] The above description is only a specific implementation manner of the present application, but the protection scope of the present application is not limited thereto. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application.

Claims

1. A multi-physics field simulation method for internal stray light, characterized in that: include: Generate a model of the system to be tested based on the assembly data of the actual mechanical model; Defining thermal characteristics, stress characteristics, boundary conditions and loads of the system to be tested model; Divide the meshes for each structural surface of the system model to be tested, perform finite element analysis and solve according to the thermal characteristics, the stress characteristics, the boundary conditions and the loads, and obtain the final steady-state value of the refractive index, the steady-state temperature field model and the deformation stress model corresponding to the system model to be tested; Importing the temperature field steady-state model and the deformation stress model into ray tracing software, and using the ray tracing software to correspond the temperature field steady-state model to each structural surface of the deformation stress model; Defining the scattering characteristics and radiation characteristics of the system to be tested model; Reversely emitting light from the imaging surfaces of the temperature field steady-state model and the deformation stress model through the ray tracing software, and using reverse ray tracing to screen key optical surfaces based on the final refractive index steady-state value, the scattering characteristics, and the radiation characteristics; The key optical surfaces are sampled and processed by the ray tracing software, and forward ray tracing is performed on the temperature field steady-state model and the deformation stress model to obtain internal stray light simulation results and path analysis results based on the final refractive index steady-state value, the scattering characteristics and the radiation characteristics.

2. The internal stray light multi-physics field simulation method according to claim 1, characterized in that: The actual mechanical model includes active devices, and the system model to be tested includes an internal heat source model corresponding to the active devices; The thermal properties include thermal conductivity, thermal expansion, thermal stability and heat capacity; the stress properties include elastic properties and expansion coefficient; The thermal characteristics and stress characteristics of the system model to be tested are the same as the thermal characteristics and stress characteristics of the actual mechanical model; the thermal characteristics and stress characteristics of the system model to be tested are defined by using a nonlinear model; The boundary conditions include the environmental conditions of the system model under test during operation; The load includes a linear model or a nonlinear model corresponding to the external environment change; The scattering properties include anisotropic scattering properties; The method further comprises: The contact type of each structural component of the system model to be tested is defined.

3. The internal stray light multi-physics field simulation method according to claim 2, characterized in that: Finite element analysis is performed according to the thermal characteristics, the stress characteristics, the boundary conditions and the load to obtain a temperature field steady-state model corresponding to the system model to be tested, including: Finite element analysis is performed based on the thermal characteristics, the boundary conditions and the loads to determine the temperature change data of each grid on each structural surface and the temperature influence between each grid. The temperature change amount of each structural component is determined based on the temperature change data of each grid on each structural surface and the temperature influence between each grid to obtain the steady-state model of the temperature field.

4. The internal stray light multi-physics field simulation method according to claim 3, characterized in that: Finite element analysis is performed according to the thermal characteristics, the stress characteristics, the boundary conditions and the load to obtain a deformation stress model corresponding to the system model to be tested, including: Obtain the relationship between the mechanical deformation and temperature of each structural component in the linear direction; According to the temperature variation of each structural component, the stress characteristics, and the relationship between the mechanical deformation and the temperature, a finite element analysis is performed to obtain the deformation stress model.

5. The internal stray light multi-physics field simulation method according to claim 4, characterized in that: Finite element analysis is performed according to the thermal characteristics, the stress characteristics, the boundary conditions and the load to obtain a final steady-state value of the refractive index corresponding to the system model to be tested, including: Obtain the relationship between the refractive index and temperature of each structural surface; According to the temperature variation of each structural surface and the relationship between the refractive index and the temperature, a finite element analysis is performed to obtain the final refractive index steady-state value.

6. The internal stray light multi-physics field simulation method according to claim 5, characterized in that: The method comprises: The relationship between the mechanical deformation and temperature of each structural component in the linear direction is determined according to the following formula 1: Formula 1: ΔL = αLΔt Wherein, ΔL represents the linear deformation of each structural part, L represents the size of each structural part in the linear deformation direction, α represents the linear expansion coefficient of each structural part, and Δt represents the temperature change of each structural body; The relationship between the refractive index and temperature of each structural surface is determined according to the following formula 2; Formula 2: n(T)=n0+dn / dT·(T−T0) Wherein, T represents the current temperature, T0 represents the reference temperature, n(T) represents the refractive index at the current temperature T, n0 represents the refractive index at the reference temperature T0, and dn / dT is the rate of change of the refractive index with temperature.

7. The internal stray light multi-physics field simulation method according to claim 1, characterized in that: The forward ray tracing of the temperature field steady-state model and the deformation stress model to obtain internal stray light simulation results and path analysis results based on the final refractive index steady-state value, the scattering characteristics and the radiation characteristics includes: The Monte Carlo method is used to calculate the radiation emittance of each structural surface at the corresponding final steady-state temperature, and the imaging surface stray light energy beam, imaging surface irradiance and imaging surface stray light incidence table are calculated.

8. An internal stray light multi-physics field simulation device, characterized in that: include: A generation module, used for generating a model of the system to be tested according to the assembly data of the actual mechanical model; A first definition module is used to define the thermal characteristics, stress characteristics, boundary conditions and loads of the system to be tested model; A processing module, used for dividing a grid for each structural surface of the system model to be tested, performing finite element analysis and solving according to the thermal characteristics, the stress characteristics, the boundary conditions and the load, to obtain a final refractive index steady-state value, a temperature field steady-state model and a deformation stress model corresponding to the system model to be tested; An import module, used for importing the temperature field steady-state model and the deformation stress model into a ray tracing software, and making the temperature field steady-state model correspond to each structural surface of the deformation stress model through the ray tracing software; A second definition module is used to define the scattering characteristics and radiation characteristics of the system model to be tested; A screening module, configured to emit light in reverse from the imaging surfaces of the temperature field steady-state model and the deformation stress model through the ray tracing software, and screen key optical surfaces based on the final refractive index steady-state value, the scattering characteristics, and the radiation characteristics by using reverse ray tracing; An acquisition module is used to sample the key optical surface through the ray tracing software, and perform forward ray tracing on the temperature field steady-state model and the deformation stress model to obtain internal stray light simulation results and path analysis results based on the final refractive index steady-state value, the scattering characteristics and the radiation characteristics.

9. A computer device, characterized in that: The computer device comprises a processor and a memory, wherein the memory stores a computer program, and the processor is configured to execute the computer program to implement the internal stray light multi-physics field simulation method according to any one of claims 1 to 7.

10. A computer storage medium, characterized in that: The device stores a computer program, which, when executed on a processor, implements the internal stray light multi-physics field simulation method according to any one of claims 1 to 7.

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