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

Abstract

The present application relates to computer simulation, and discloses a multi-physical field simulation method, device, equipment and medium for internal stray light. The method includes: generating a to-be-tested system model according to the assembly data of an actual mechanical model; dividing meshes for each structural surface of the to-be-tested system model, and performing finite element analysis and solution according to thermal characteristics, stress characteristics, boundary conditions and loads to obtain the final steady-state refractive index value, steady-state temperature field model and deformation stress model; importing the steady-state temperature field model and the deformation stress model into ray tracing software; reversely emitting rays from the imaging surface of the steady-state temperature field model and the deformation stress model through the ray tracing software, and screening key optical surfaces by using reverse ray tracing; performing sampling processing on the key optical surfaces by using forward ray tracing, and performing forward ray tracing on the steady-state temperature field model and the deformation stress model to obtain internal stray light simulation results and path analysis results. In this way, the accuracy of internal stray light analysis is improved.

Description

Technical Field

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

[0002] From the perspective of research mechanism, there are two research methods for the self-heating radiation of a system: one is the BAT (built-and-test) method, that is, first manufacturing a prototype, and then using a measurement system to measure the stray radiation level of the system. The other is the software modeling and analysis method, that is, using a large analysis software to conduct a stray radiation simulation test analysis on the system. From the perspective of research methods, the analysis methods for self-heating radiation include the Monte Carlo method, the ray tracing method, and the zonal method. In the prior art, a complete simulation method for internal stray light has not been formed, and the prior art cannot be transplanted into the analysis of internal stray light, and there is no simulation method that can include all the influencing factors of internal stray light. Summary of the Invention

[0003] In a first aspect, the present invention provides a multi-physical field simulation method for internal stray light, including:

[0004] Generating a to-be-tested system model according to the assembly data of an actual mechanical model;

[0005] Defining the thermal characteristics, stress characteristics, boundary conditions and loads of the to-be-tested system model;

[0006] Dividing grids for each structural surface of the to-be-tested system model, and performing 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 to-be-tested system model;

[0007] Importing the temperature field steady-state model and the deformation stress model into a ray tracing software, and corresponding each structural surface of the temperature field steady-state model and the deformation stress model through the ray tracing software;

[0008] Defining the scattering characteristics and radiation characteristics of the to-be-tested system model;

[0009] Backwardly emitting light rays from the imaging surface of the temperature field steady-state model and the deformation stress model through the ray tracing software, and screening key optical surfaces based on the final refractive index steady-state value, the scattering characteristics and the radiation characteristics by using backward ray tracing;

[0010] Sampling the key optical surfaces through the ray tracing software, and performing forward ray tracing on the steady-state temperature field model and the deformation stress model to obtain the internal stray light simulation results and path analysis results based on the final steady-state refractive index value, the scattering characteristics, and the radiation characteristics.

[0011] In an alternative embodiment, the actual mechanical model includes active devices, and the system model to be measured includes an internal heat source model corresponding to the active devices.

[0012] The thermal characteristics include thermal conductivity, thermal expansion, thermal stability, and heat capacity; the stress characteristics include elastic characteristics and coefficient of expansion.

[0013] The thermal characteristics and stress characteristics of the system model to be measured are the same as those of the actual mechanical model; the thermal characteristics and stress characteristics of the system model to be measured are defined using a non-linear model.

[0014] The boundary conditions include the environmental conditions during the operation of the system model to be measured; the loads include a linear model or a non-linear model corresponding to changes in the external environment.

[0015] The scattering characteristics include anisotropic scattering characteristics.

[0016] The method further includes:

[0017] Defining the contact types of the various structural components of the system model to be measured.

[0018] In an alternative embodiment, performing finite element analysis and solution based on the thermal characteristics, the stress characteristics, the boundary conditions, and the loads to obtain the steady-state temperature field model corresponding to the system model to be measured, including:

[0019] Performing finite element analysis and solution based on the thermal characteristics, the boundary conditions, and the loads to determine the temperature change data of each grid of each structural surface and the temperature interaction between the grids, and determining the temperature change amount of each structural component based on the temperature change data of each grid of each structural surface and the temperature interaction between the grids to obtain the steady-state temperature field model.

[0020] In an alternative embodiment, performing finite element analysis and solution based on the thermal characteristics, the stress characteristics, the boundary conditions, and the loads to obtain the deformation stress model corresponding to the system model to be measured, including:

[0021] Obtaining the relationship between the mechanical deformation amount and temperature of each structural component in the linear direction.

[0022] Based on the temperature change of each structural member, the stress characteristics, and the relationship between the mechanical deformation amount and temperature, perform finite element analysis and solution to obtain the deformation stress model.

[0023] In an alternative embodiment, perform finite element analysis and solution based on the thermal characteristics, the stress characteristics, the boundary conditions, and the load to obtain the final refractive index steady-state value corresponding to the system model to be measured, including:

[0024] Obtain the relationship between the refractive index and temperature of each structural surface;

[0025] Based on the temperature change of each structural surface and the relationship between the refractive index and temperature, perform finite element analysis and solution to obtain the final refractive index steady-state value.

[0026] In an alternative embodiment, the method includes:

[0027] Determine the relationship between the mechanical deformation amount and temperature of each structural member in the linear direction according to the following formula 1:

[0028] Formula 1: ΔL = αLΔt

[0029] Where, ΔL represents the linear deformation amount of each structural member, L represents the dimension of each structural member in the linear deformation direction, α represents the linear expansion coefficient of each structural member, and Δt represents the temperature change amount of each structural body;

[0030] Determine the relationship between the refractive index and temperature of each structural surface according to the following formula 2;

[0031] Formula 2: n(T) = n 0 + dn / dT·(T − T 0 )

[0032] Where, T represents the current temperature, T 0 represents the reference temperature, n(T) represents the refractive index at the current temperature T, n 0 represents the refractive index at the reference temperature T 0 , and dn / dT is the rate of change of the refractive index with temperature.

[0033] In an alternative 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:

[0034] Adopt the Monte Carlo method to calculate the radiant emittance of each structural surface at the corresponding final steady-state temperature, and calculate the stray light energy beam on the imaging surface, the irradiance on the imaging surface, and the stray light incidence table on the imaging surface.

[0035] In a second aspect, the present invention provides an internal stray light multi-physical field simulation device, comprising:

[0036] A generation module, configured to generate a system model to be measured according to the assembly data of an actual mechanical model;

[0037] A first definition module, configured to define the thermal characteristics, stress characteristics, boundary conditions and loads of the system model to be measured;

[0038] A processing module, configured to divide grids for each structural surface of the system model to be measured, and perform finite element analysis and solution according to the thermal characteristics, the stress characteristics, the boundary conditions and the loads, so as 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 measured;

[0039] An import module, configured to import the temperature field steady-state model and the deformation stress model into ray tracing software, and make the respective structural surfaces of the temperature field steady-state model and the deformation stress model correspond through the ray tracing software;

[0040] A second definition module, configured to define the scattering characteristics and radiation characteristics of the system model to be measured;

[0041] A screening module, configured to reverse the outgoing light from the imaging surface 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;

[0042] An acquisition module, configured to perform sampling processing on the key optical surfaces through the ray tracing software, and perform 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 based on the final refractive index steady-state value, the scattering characteristics and the radiation characteristics.

[0043] In a third aspect, the present invention provides a computer device, which includes a processor and a memory, the memory stores a computer program, and the processor is configured to execute the computer program to implement the internal stray light multi-physical field simulation method according to any one of the foregoing embodiments.

[0044] In a fourth aspect, the present invention provides a computer storage medium, which stores a computer program, and when the computer program is executed on a processor, the internal stray light multi-physical field simulation method according to any one of the foregoing embodiments is implemented.

[0045] The internal stray light multi-physical field simulation method provided by the present application generates a system model to be measured according to the assembly data of an actual mechanical model; defines the thermal characteristics, stress characteristics, boundary conditions, and loads of the system model to be measured; divides grids for each structural surface of the system model to be measured, and performs finite element analysis and solution according to the thermal characteristics, stress characteristics, boundary conditions, and 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 measured; imports the temperature field steady-state model and the deformation stress model into ray tracing software, and corresponds each structural surface of the temperature field steady-state model and the deformation stress model through the ray tracing software; defines the scattering characteristics and radiation characteristics of the system model to be measured; emits rays reversely from the imaging surface of the temperature field steady-state model and the deformation stress model through the ray tracing software, and uses reverse ray tracing to screen key optical surfaces based on the final refractive index steady-state value, the scattering characteristics, and the radiation characteristics; performs sampling processing on the key optical surfaces through the ray tracing software, and performs forward ray tracing on the temperature field steady-state model and the deformation stress model to obtain an internal stray light simulation result and a path analysis result based on the final refractive index steady-state value, the scattering characteristics, and the radiation characteristics. In this way, by using multi-physical field simulation, the important influencing factor of internal stray light, the temperature field, is introduced into the stray light simulation, and finally an internal stray light analysis method with multi-physical field coupling is realized, improving the accuracy of stray light analysis. Description of the Drawings

[0046] In order to more clearly illustrate the technical solutions of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present application and should not be regarded as limiting the protection scope of the present application. For those of ordinary skill in the art, other related drawings can be obtained based on these drawings without creative efforts.

[0047] Figure 1 Fig. shows a schematic flowchart of the internal stray light multi-physical field simulation method provided by an embodiment of the present application;

[0048] Figure 2 Fig. shows a schematic structural diagram of an internal stray light multi-physical field simulation device provided by an embodiment of the present application.

[0049] Reference numerals: 200 - internal stray light multi-physical 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 Embodiments

[0050] Next, the technical solutions in the embodiments of the present application will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments.

[0051] Generally, the components of the embodiments of the present application described and illustrated in the accompanying drawings herein can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the present application claimed, but merely represents selected embodiments of the present application. All other embodiments obtained by those skilled in the art based on the embodiments of the present application without creative efforts belong to the scope of protection of the present application.

[0052] Hereinafter, the terms "including", "having" and their cognates that can be used in various embodiments of the present application are only intended to indicate specific features, numbers, steps, operations, elements, components or combinations of the foregoing items, and should not be construed as first excluding the existence of one or more other features, numbers, steps, operations, elements, components or combinations of the foregoing items or increasing the possibility of one or more features, numbers, steps, operations, elements, components or combinations of the foregoing items.

[0053] In addition, the terms "first", "second", "third", etc. are only used for distinguishing descriptions and cannot be construed as indicating or implying relative importance.

[0054] Unless otherwise defined, all terms (including technical terms and scientific terms) used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the various embodiments of the present application belong. The terms (such as those defined in a general-use dictionary) will be construed to have the same meaning as the contextual meaning in the relevant technical field and will not be construed to have an idealized meaning or an overly formal meaning unless clearly defined in the various embodiments of the present application.

[0055] For the comparison of the characteristics of existing BAT methods and software model simulations, see Table 1.

[0056] Table 1. Comparison Table of the Characteristics of BAT Methods and Software Model Simulations

[0057]

[0058] As can be seen from the above table, when using large-scale analysis software to simulate and analyze a detection system, if the system parameters input during modeling can be ensured to be accurate enough, then its disadvantages can be ignored, while its advantages are very obvious. Especially for the analysis of the stray radiation of an infrared detection system, it is very difficult to use the BAT experimental test method, and the error is also very large. Using 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 operates in the infrared band, and the influence on system components can also be analyzed separately. Therefore, at present, the prediction and evaluation of the stray radiation of infrared systems mainly rely on software simulation calculation and analysis.

[0059] The Monte Carlo method, ray tracing method, and zonal method will be introduced below. The Monte Carlo method (Monte-Carlo Method or MCM) is a computer simulation method using random variables for statistics that developed with the emergence of computers. It was first applied to the research of atomic bombs. Howell applied this method to the calculation of radiative heat transfer. He regarded processes such as emission, reflection, transmission, scattering, and absorption in the process of radiative energy transfer as independent of each other, and then established a probability model related to surface characteristics for each sub-process. Let each unit emit a certain number of energy beams, trace each energy beam until the termination condition is met, and count the destinations of each energy beam to obtain the statistical results of the radiation energy distribution of this unit.

[0060] The ray tracing method uses definite formulas instead of statistical methods to analyze and calculate stray light. This method has developed on the following two bases: First, due to the emergence of different ray tracing programs, it is easy to obtain the path of weighted rays passing 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 rays emitted from the aperture edge. For the calculation of the reflection part, it is carried out by successively determining the area of the critical surface. The surface that can be directly or indirectly seen by the receiver in the optical system is called the critical surface. If the part that can be directly seen is called the first-level critical surface, and the indirectly seen part is the second-level or higher-level critical surface. By successively solving the area, illuminance, and diffuse reflection coefficient of the critical surface, the stray radiation generated by diffuse reflection can be calculated. The intersection points of the rays passing through the optical system and the receiving surface are represented by a spot diagram. Each point on the diagram represents a portion of light energy. By calculating the weighted number of dots per unit area, the illuminance generated by imaging and non-imaging beams can be obtained. Obviously, to obtain higher accuracy, more dots need to be calculated.

[0061] The zonal method, also known as the finite element method, is the same as the ray tracing method in that it is also a deterministic method for calculating stray radiation. The zonal method for calculating stray light is based on the energy transfer equation. The various structural surfaces of the system are divided into many small zones, and the direct radiation transmission between every two zones is calculated to obtain the transfer process of the radiation energy in the entire system and the energy finally reaching the image plane. The calculation accuracy of this method depends on the number of small zones divided. The parts with a relatively large contribution to stray light should be divided more finely. When calculating stray light using this method, in order to improve 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.

[0062] Compared with the Monte Carlo method, the zonal method does not require tracing a large number of rays, but it needs to calculate the energy transfer of a large number of zones, and it is necessary to judge the possible paths of stray light transmission in advance. Otherwise, a lot of unnecessary calculations will be added, seriously affecting the speed. The difference between the ray tracing method and the Monte Carlo method is that the ray tracing method uses a definite formula to replace the traditional method to calculate stray light. It is very similar to the zonal method and also belongs to the method of deterministic calculation. The difference is that the ray tracing method uses the method of geometric optics calculation to carry out the ray transfer calculation.

[0063] In summary, in the prior art, there is no complete simulation method for internal stray light, and the prior art cannot be transplanted into the analysis of internal stray light. There is no simulation method that can include all the influencing factors of internal stray light.

[0064] Next, in conjunction with the accompanying drawings, some embodiments of the present application will be described in detail. Without conflict, the following embodiments and the features in the embodiments can be combined with each other.

[0065] This embodiment provides a multi-physics field simulation method for internal stray light, which makes up for the gap in the simulation and calculation of internal stray light, realizes a comprehensive and efficient full-link simulation, and improves the accuracy of the simulation analysis of internal stray light.

[0066] See Figure 1 , the multi-physics field simulation method for internal stray light provided by this embodiment includes steps S101-S107, and each step will be described below.

[0067] Step S101, generate a to-be-tested system model according to the assembly data of the actual mechanical model.

[0068] In this embodiment, the internal stray light multi-physical 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 that can generate heat or refrigerate, and the active devices include heat-generating components. The system model to be measured includes an internal heat source model corresponding to the active device. For example, the system model to be measured operates in the thermal infrared band, contains active devices inside, and there are self-heating sources inside the system. The system model to be measured 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 device, its heat generation power needs to be accurately calculated, as well as the main positions where the active device generates heat. The heat generation power can generally be referred to in its user manual, and the main heat generation positions are related to the type of active device. For example, the heat generation positions of a switching power supply are capacitors and relays, and the heat generation positions of a spectroscopic crystal are transducers.

[0069] It should be noted that in this embodiment, the internal stray light mainly considers the thermal infrared band, that is, the mid-wave infrared and the long-wave infrared. External stray light is caused by other light sources, while 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 methods in the prior art are for analyzing external stray light. Therefore, the temperature change does not need to be considered. After only accurately establishing the stress change of the mechanical structure and the model of the mechanical structure, the external stray light simulation can be completed. However, internal stray light is closely related to temperature, and factors such as the environmental temperature change during the operation of the overall system and the possible heat generation of active devices need to be considered. Therefore, the existing external stray light simulation scheme cannot be used to simulate the internal stray light of the mechanical system.

[0070] Furthermore, it should be added that the internal stray light multi-physical field simulation method further includes:

[0071] Defining the contact types of the structural components of the system model to be measured.

[0072] It can be understood that due to the existence of the internal self-heating source in the system, when the heat source is actually working, it will transfer its own heat generation to all the surrounding components in contact through heat conduction, thereby affecting the overall temperature. After the overall temperature changes, there will also be heat convection in the air with the surrounding environmental temperature, and heat radiation heat transfer will also occur between all the components in the overall system. Therefore, it is necessary to additionally define the contact types of the structural components 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.

[0073] Furthermore, in a system with active devices, the heat transfer mode 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 temperature and the minimum temperature in the system may differ by dozens of degrees Celsius or even hundreds of degrees Celsius. If the traditional method for analyzing external stray light is used, this system is considered to be a system with a uniform and stable temperature distribution, and correspondingly, there will be no heat exchange or thermal deformation, and thus the overall transmission efficiency of the optical path and the stray light transmission path will not be affected. Therefore, for internal stray light, especially internal stray light containing active devices, multi-physics field simulations need to be introduced, including multi-physics field simulations of mechanical deformation, temperature, stress, optics, etc. The mutual influence factors of different physical fields are accurately calculated and introduced into the simulations of each physical field.

[0074] S102. Define the thermal characteristics, stress characteristics, boundary conditions, and loads of the system model to be measured.

[0075] In this embodiment, the thermal characteristics include characteristics such as thermal conductivity, thermal expansibility, thermal stability, and heat capacity. The stress characteristics include characteristics such as elastic characteristics and expansion coefficients. After the solution of the material thermal characteristics simulation becomes effective, each structural member of the actual mechanical model will generate temperature changes and deformations following its own thermal characteristics and stress characteristics. The thermal characteristics and stress characteristics of the system model to be measured are the same as those of the actual mechanical model; the thermal characteristics and stress characteristics of the system model to be measured are defined using a non-linear model. The thermal characteristics and stress characteristics of the system model to be measured are defined as corresponding non-linear models according to the actual thermal characteristics and stress characteristics of the actual mechanical model.

[0076] In this embodiment, the boundary conditions include the environmental conditions during the operation of the system model to be measured; the environmental conditions include environmental temperature, environmental convection characteristics, and environmental pressure, etc. For example, the environmental conditions of the system model to be measured are: placed in a super clean laboratory with a constant temperature of 22°C, and the environment is a standard atmospheric pressure without wind.

[0077] The loads include linear models or non-linear models corresponding to external environmental changes. The loads are the static loads and dynamic loads of the system model to be measured. Specifically, according to the external environmental change situation of the system model to be measured, the loads are defined as linear models or non-linear models, and the linear models or non-linear models of the loads are consistent with the external environmental changes.

[0078] Among them, the static load can be understood as a constant. For example, in an optical system, there is a heat source with a fixed power, and the fixed power of the heat source is the static load. The dynamic load refers to a quantity that changes with time, such as the changing room temperature, etc. For example, if the load is a lighting fixture and its power and light quantity can be kept unchanged, it is a static load. If this heat source is still in an unstable stage and its power and light quantity are dynamically changing, it is a dynamic load.

[0079] S103, divide grids for each structural surface of the to-be-tested system model, and perform finite element analysis and solution according to the thermal characteristics, the stress characteristics, the boundary conditions, and the load to obtain the final refractive index steady-state value, the temperature field steady-state model, and the deformation stress model corresponding to the to-be-tested system model.

[0080] In this embodiment, by combining the interactions between multiple physical fields, a model calculation is performed for the multiple physical fields, and then the influence degree 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 divided grids is related to the simulation tool. The more grids there are, the more accurate the solution result will be, but it will affect the operation efficiency of the computer. Among them, the temperature field steady-state model is the overall temperature distribution result after the final system stabilizes. This result can be expressed as a contour map or as the temperature data of several grid points, and there is no limit here.

[0081] In this embodiment, the main optical axis of the to-be-tested system model is perpendicular to the surfaces of each structural member (component). The temperature field steady-state model can be referenced by setting the average temperature value of each divided surface. If the to-be-tested system model is an optical system, the main optical axis refers to the optical direction of the optical system. For example, the optical axis direction of a lens set in the Z direction is the X-axis direction or the Y-axis direction. Each component is all the optical elements in the optical system.

[0082] It should be further supplemented that when analyzing by dividing grids, the number of grids on each surface is specific. The thermal radiation value of each surface can be the integral between grids with non-uniform temperatures, or can be directly solved using the average temperature. That is, the temperature field steady-state model can be referenced not only by setting the average temperature value of each divided surface, but also by the integral between grids with non-uniform temperatures.

[0083] In an implementation manner, performing finite element analysis and solution according to the thermal characteristics, the stress characteristics, the boundary conditions, and the load to obtain the temperature field steady-state model corresponding to the to-be-tested system model includes:

[0084] Perform finite element analysis and solution according to the thermal characteristics, the boundary conditions, and the loads to determine the temperature change data of each grid of each structural surface and the temperature interaction between grids, and determine the temperature change amount of each structural member according to the temperature change data of each grid of each structural surface and the temperature interaction between grids, so as to obtain the steady-state temperature field model.

[0085] For example, a structural surface has 100 grids. Among them, the temperature of the first grid is 10 °C, and the temperature of the second grid is 20 °C. Then, there will be a gradual change process in the temperatures of the first grid and the second grid, and the interaction between the two grids during the temperature gradual change process can be referred to as the temperature interaction between grids.

[0086] Exemplarily, solve through finite element analysis to individually derive the average temperature value of each surface of the system model to be measured, and then input it into the temperature definition of each surface to obtain the steady-state temperature field model.

[0087] In one embodiment, perform finite element analysis and solution according to the thermal characteristics, the stress characteristics, the boundary conditions, and the loads to obtain the deformation stress model corresponding to the system model to be measured, including:

[0088] Obtain the relationship between the mechanical deformation amount and temperature of each structural member in the linear direction;

[0089] Perform finite element analysis and solution according to the temperature change amount of each structural member, the stress characteristics, and the relationship between the mechanical deformation amount and temperature to obtain the deformation stress model.

[0090] In one embodiment, the internal stray light multi-physical field simulation method further includes:

[0091] Determine the relationship between the mechanical deformation amount and temperature of each structural member in the linear direction according to the following formula 1:

[0092] Formula 1: ΔL = αLΔt

[0093] ΔL represents the linear deformation amount of each structural member, L represents the dimension (mm) of each structural member in the linear deformation direction, α represents the linear expansion coefficient (per °C) of each structural member. 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 a system with a large ambient temperature change range or the presence of active devices, there is a rated change relationship curve between α and temperature, which is related to the characteristics of the material itself. This expansion coefficient is one of the stress characteristics. Δt represents the temperature change amount (°C) of each structural body. The temperature change amount of each structural body is one of the thermal characteristics.

[0094] In this embodiment, the linear changes of the structural member in each direction can be accurately calculated by the finite element method, and then the overall deformation amount and deformation result in the 360° spherical space can be calculated. Exemplarily, a program code is set, and the program code includes the correlation formulas regarding all thermal characteristics, the stress characteristics, the boundary conditions, and the loads. The finite element solution is adopted, the object to be solved is divided into very small n meshes, and then the deformation results inside the n meshes and the deformation influence results between the n meshes are solved respectively. Finally, the overall deformation amount and deformation result are obtained, and a deformation stress model is obtained.

[0095] In one embodiment, finite element analysis and solution are performed according to the thermal characteristics, the stress characteristics, the boundary conditions, and the loads to obtain the final refractive index steady-state value corresponding to the to-be-tested system model, including:

[0096] Obtain the relationship between the refractive index and temperature of each structural surface;

[0097] According to the temperature change amount of each structural surface and the relationship between the refractive index and temperature, perform finite element analysis and solution to obtain the final refractive index steady-state value.

[0098] It should be noted that the influence of mechanical deformation on light transmission is very intuitive. Light transmission follows the laws of refraction and reflection, etc. Therefore, any tiny deformation will cause a change in the light transmission angle, which will further affect the capture of effective optical signals and the generation of stray light in the system. By calculating the structure after mechanical deformation, the model idealization error in the subsequent Monte Carlo calculation is avoided. Through the solution calculation of the foregoing steps, the mechanical structure model after deformation stabilization is adopted to calculate the actual light transmission result, effectively reducing the error in terms of stress in the final result.

[0099] It can be understood that the influence of temperature on optical elements mainly includes refractive index and thermal expansion, etc. The relationship between temperature and refractive index is not a simple formula relationship, and it usually shows a complex non-linear 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 can be 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 the finite element method, so that the corresponding refractive index change can be obtained.

[0100] In one embodiment, the multi-physical field simulation method for internal stray light further includes:

[0101] Determine the relationship between the refractive index and temperature of each structural surface according to the following formula 2;

[0102] Formula 2: n(T)=n0 +dn / dT·(T−T 0 )

[0103] where T represents the current temperature, T 0 represents the reference temperature, n(T) represents the refractive index at the current temperature T, and n 0 represents the refractive index at the reference temperature T 0 . 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. Equation 2 assumes that near the temperature T0, the change of the refractive index with temperature is linear, that is, the rate of change dn / dT is a constant.

[0104] 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 foregoing steps, the refractive index parameters after temperature stabilization are adopted to calculate the actual light transmission result, effectively reducing the error in terms of temperature in the final result.

[0105] S104. Import the temperature field steady-state model and the deformation stress model into the ray tracing software, and correspond each structural surface of the temperature field steady-state model with that of the deformation stress model through the ray tracing software.

[0106] In this embodiment, the ray tracing software can adopt TRACEPRO, which is a set of optical simulation software commonly used for lighting systems, optical analysis, radiance analysis, and photometry analysis. Import the deformation stress model and the temperature field steady-state model into the TRACEPRO software, correspond the temperature field steady-state model to each structural surface of the deformation stress model, and calculate the stray light data of the imaging surface. The ray tracing software uses the Monte Carlo analysis method to calculate the stray light data of the imaging surface in the deformation stress model.

[0107] 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 object surface, through experiments, for a small laboratory optical system, the average temperature of each structural surface can be used as the thermal radiation temperature reference for its entire surface. For a large space-based system or remote sensing system, 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 surface average temperature calculated above can be directly used for the surface radiation characteristic setting, material refractive index and other parameter design, and other temperature-related parameter settings in the ray tracing software. The radiant emittance of each surface is proportional to the temperature. The higher the temperature, the more radiation and the greater the thermal radiation stray light. The deformation and temperature change of the model system to be measured occur simultaneously, and the calculated surface average temperature is the final surface average temperature.

[0108] S105, define the scattering characteristics and radiation characteristics of the system model to be measured.

[0109] 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 has an approximately linear relationship with the temperature. The smaller the ray tracing threshold, the higher the solution accuracy of reverse ray tracing or forward ray tracing. 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.

[0110] It should be added that the radiant emittance of the self-heating radiation stray light of an object refers to the total energy of electromagnetic waves of various wavelengths emitted per unit area of the object surface per unit time, expressed in M . It can be deduced from Planck's law that when the wavelength and temperature T are determined, the relationship between the blackbody radiant emittance and the wavelength and temperature is expressed by the following formula 3:

[0111] Formula 3:

[0112] In the formula, c 1 is the first radiation constant 3.7418×10 -16 W•m 2 , c 2 is the second radiation constant 1.4388×10 -2 mK.

[0113] In addition, the Stefan-Boltzmann law describes the relationship between the radiant emittance of an object and the absolute temperature, as expressed by the following formula 4:

[0114] Formula 4:

[0115] In the formula, has a value of 5.670373×10 -12 W·cm -2 ·K -4 , which is called the Stefan-Boltzmann constant. It can be seen from the above formula that the radiant emittance of an object is proportional to the fourth power of the temperature.

[0116] 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.

[0117] 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.

[0118] 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.

[0119] 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.

[0120] 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.

[0121] 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.

[0122] In this embodiment, the internal stray light simulation result includes an imaging surface irradiance and an imaging surface stray light incidence table.

[0123] In this way, the critical optical surfaces are renovated for ray tracing, improving tracing efficiency and accuracy.

[0124] It can be understood that most of the existing technologies simulate the stray light outside the field of view (i.e., external stray light), lacking the accurate calculation of the internal stray light (i.e., the stray light generated by the system's self-heating). By adopting the multi-physics field simulation method for internal stray light provided in this embodiment, the quantitative calculation of the internal stray light can be realized. When simulating the stray light outside the field of view in the existing technology, only the stress field is considered as other physical fields, without considering the influence of other physical fields such as the temperature field on the overall structure and optical path of the system to be measured. The multi-physics field simulation method for internal stray light provided in this embodiment combines multi-physics field simulation, introduces the important influencing factors of internal stray light, namely the temperature field and refractive index change, into the stray light simulation, and finally realizes the analysis method of internal stray light with multi-physics field coupling, improving the accurate analysis of internal stray light.

[0125] In one embodiment, the forward ray tracing of the temperature field steady-state model and the deformation stress model is performed 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, including:

[0126] The Monte Carlo method is used to calculate the radiant emittance of each structural surface at the corresponding final steady-state temperature, and the stray light energy beam, irradiance, and incident table of the imaging surface are calculated.

[0127] In this embodiment, the influencing factors of the internal stray light are calculated and fused. Through the fusion simulation of multiple physical fields, combined with the actual operating environment and scenario, the accurate numerical value of the internal stray light of the system and the optical path are calculated, which has guiding significance for the subsequent optical analysis and correction of the system.

[0128] This embodiment also provides a multi-physics field simulation device for internal stray light. Refer to Figure 2 , the multi-physics field simulation device 200 for internal stray light includes:

[0129] A generation module 201, configured to generate a system model to be measured according to the assembly data of the actual mechanical model;

[0130] A first definition module 202, configured to define the thermal characteristics, stress characteristics, boundary conditions, and loads of the system model to be measured;

[0131] A processing module 203, configured to divide grids for each structural surface of the system model to be measured, perform finite element analysis and solution according to the thermal characteristics, stress characteristics, boundary conditions, and 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 measured;

[0132] An import module 204 is configured to import the steady-state temperature field model and the deformation stress model into ray tracing software, and correspond each structural surface of the steady-state temperature field model and the deformation stress model through the ray tracing software;

[0133] A second definition module 205 is configured to define the scattering characteristics and radiation characteristics of the to-be-tested system model;

[0134] A screening module 206 is configured to reverse the outgoing light rays from the imaging surface of the steady-state temperature field 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;

[0135] An acquisition module 207 is configured to perform sampling processing on the key optical surfaces through the ray tracing software, and perform forward ray tracing on the steady-state temperature field model and the deformation stress model, so as to obtain an internal stray light simulation result and a path analysis result based on the final refractive index steady-state value, the scattering characteristics, and the radiation characteristics.

[0136] It can be understood that the internal stray light multi-physical field simulation device in this embodiment corresponds to the internal stray light multi-physical field simulation method in the above embodiment. The optional items in the above embodiment are also applicable to this embodiment, so they will not be described repeatedly here.

[0137] The present application further provides a computer device. Exemplarily, the computer device includes a processor and a memory. The memory stores a computer program, and the processor runs the computer program to enable the computer device to execute the above internal stray light multi-physical field simulation method or the functions of each module in the above internal stray light multi-physical field simulation device.

[0138] Among them, the processor can be an integrated circuit chip with signal processing capabilities. The processor can be a general-purpose processor, including at least one of 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 other programmable logic devices, discrete gate 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., and can implement or execute the various methods, steps, and logic block diagrams disclosed in the embodiments of the present application.

[0139] The memory can be, but is not limited to, Random Access Memory (RAM), Read Only Memory (ROM), Programmable Read-Only Memory (PROM), Erasable Programmable Read-Only Memory (EPROM), Electric Erasable Programmable Read-Only Memory (EEPROM), etc. Among them, the memory is used to store a computer program, and after receiving an execution instruction, the processor can execute the computer program accordingly.

[0140] This application also provides a computer storage medium for storing the computer program used in the above computer device. Among them, the computer storage medium can be a readable storage medium, a non-volatile storage medium or a volatile storage medium. For example, the computer storage medium can include, but is not limited to: USB flash drive, mobile hard disk, Read Only Memory (ROM), Random Access Memory (RAM), magnetic disk or optical disc and other various media that can store program codes.

[0141] In several embodiments provided by this application, it should be understood that the disclosed device and method can also be implemented in other ways. The device embodiments described above are only illustrative. For example, the flowcharts and structure diagrams in the drawings show the possible architectures, functions and operations of the device, method and computer program product according to multiple embodiments of this application. In this regard, each block in the flowchart or block diagram can represent a module, a program segment or a part of code, and the module, program segment or part of 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 blocks can occur in a different order than marked in the drawings. For example, two consecutive blocks can actually be executed substantially in parallel, and they can sometimes be executed in the reverse order, depending on the functions involved. It should also be noted that each block in the structure diagram and / or flowchart, as well as the combination of blocks in the structure diagram and / or flowchart, can be implemented by a dedicated hardware-based system that executes the specified functions or actions, or can be implemented by a combination of dedicated hardware and computer instructions.

[0142] In addition, each functional module or unit in various embodiments of the present application may be integrated together to form an independent part, or each module may exist alone, or two or more modules may be integrated to form an independent part.

[0143] If the above-mentioned function is implemented in the form of a software functional module and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on such an understanding, the technical solution of the present application, in essence, or the part that contributes to the prior art, or a part of this technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions for causing a computer device (which may 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 various embodiments of the present application.

[0144] The above is only the specific implementation manner of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present application can easily think of changes or substitutions, which should all be covered by 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 surface is sampled by the ray tracing software, and the temperature field steady-state model and the deformation stress model are forward traced 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; 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: Defining the contact type of each structural component of the system model to be tested; 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: Performing finite element analysis and solving according to the thermal characteristics, the boundary conditions and the loads to determine the temperature change data of each grid of each structural surface and the temperature mutual influence between each grid, determining the temperature change amount of each structural component according to the temperature change data of each grid of each structural surface and the temperature mutual influence between each grid, and obtaining the temperature field steady-state model; 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; 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.

2. The internal stray light multi-physics field simulation method according to claim 1, 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.

3. 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.

4. 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, configured to perform sampling processing on 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, 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; 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; Also includes: Defining the contact type of each structural component of the system model to be tested; 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: Performing finite element analysis and solving according to the thermal characteristics, the boundary conditions and the loads to determine the temperature change data of each grid of each structural surface and the temperature mutual influence between each grid, determining the temperature change amount of each structural component according to the temperature change data of each grid of each structural surface and the temperature mutual influence between each grid, and obtaining the temperature field steady-state model; 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; 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.

5. 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 3.

6. 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 3.

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