Dynamic optical-mechanical coupling ray tracing method

Abstract

The invention discloses a dynamic optical-mechanical coupling ray tracing method, which solves the problems that the micro-vibration optical-mechanical integrated analysis technology of a space optical remote sensor is low in efficiency and does not comprehensively consider the elastic deformation of a mirror surface of an optical element, and comprises the following steps: firstly, carrying out finite element modeling on an optical system of the space optical remote sensor, and applying micro-vibration as input; obtaining the structural dynamic response of each component of the optical system under the action of micro-vibration, and obtaining the node displacement of the focused optical surface; reconstructing a smooth optical surface by adopting an interpolation method based on node displacement; establishing an optical-mechanical coupling ray tracing model; and carrying out dynamic ray tracing on the space optical remote sensor based on the ray-machine coupling ray tracing model to obtain the dynamic wavefront difference of the space optical remote sensor. The dynamic analysis of the optical system of the space optical remote sensor is realized by combining various analysis methods, the analysis of optical-mechanical system integration is realized through optical-mechanical coupling, and the dynamic efficient analysis of the influence of micro-vibration on the imaging quality of the space optical remote sensor is realized.

Description

Technical Field

[0001] The invention relates to the technical field of optical-mechanical integration analysis of a space optical remote sensor reflection or refraction system, and in particular to a dynamic optical-mechanical coupling ray tracing method. Background Art

[0002] With the continuous development and progress of my country's aerospace industry, aerospace optical cameras are developing towards the trend of large aperture, large field of view, high resolution and lightweight. At present, the ground pixel resolution of aerospace optical cameras has entered the sub-meter level. High-precision and high-quality optical cameras have higher and higher requirements for the overall optical axis pointing stability and imaging quality of the platform and optical system during on-orbit imaging. The focal length and aperture of the optical system are constantly increasing, and the rigidity of the optomechanical system is limited by mass and has limited room for improvement. It is also increasingly sensitive to the micro-vibration caused by the normal operation of the on-orbit moving parts. Micro-vibration will affect the on-orbit imaging quality of aerospace optical cameras. In particular, large-aperture, long-focal-length, reflective optical systems have the characteristics of high specific stiffness and low absolute stiffness, which leads to a sharp increase in the sensitivity of the optomechanical structure to mechanical and thermal loads. When the satellite is launched into orbit, the disturbance sources such as the moving parts of its platform act on the structure of the satellite and are transmitted to the remote sensor, which will cause the optical system to vibrate micro-vibration in the inertial space. Regardless of the imaging method used (including area array staring, linear array push scanning, etc.), micro-vibration will cause disturbances in the optical axis of the optical system and the internal optical elements, resulting in a decrease in the system's Modulation Transfer Function (MTF) and image quality degradation, which greatly restricts the imaging quality of the system.

[0003] At present, the main technical approach to studying the micro-vibration of aerospace optical cameras is to regard the camera and the entire satellite structure as elastic bodies, and then simplify it into the problem of the dynamics of the entire satellite structure. However, there are certain shortcomings in the simplification process: simplifying the optical camera into a single mass point or multiple mass points with rigid coupling ignores the influence of the structural micro-vibration of the optical elements inside the remote sensor on the imaging quality; and failing to comprehensively consider the influence of the superposition of the elastic deformation of the mirrors of all optical elements on the dynamic wavefront difference of the whole system (imaging quality of the optical system), which is inefficient and the effect is not significant. At present, there is no effective optomechanical coupling ray tracing method that can efficiently analyze the influence of micro-vibration on the imaging quality of space optical remote sensors. Summary of the invention

[0004] The purpose of the present invention is to provide a dynamic optomechanical coupling ray tracing method that can solve the problems of low efficiency, insignificant effect, and inability to comprehensively consider the influence of the elastic deformation of the mirror surfaces of all optical elements on the imaging quality of the optical system in the micro-vibration optomechanical integrated analysis technology of space optical remote sensors.

[0005] In order to achieve the above object, the present invention provides the following technical solutions:

[0006] A dynamic optomechanical coupling ray tracing method comprises the following steps:

[0007] Step 1: Use finite element analysis software to perform finite element modeling on the optical system of the space optical remote sensor, apply micro-vibration as the input of the structural finite element model, obtain the structural dynamic response of each component of the optical system under the action of micro-vibration, and process the structural dynamic analysis results to obtain the node displacement of the optical surface of interest;

[0008] Step 2: Based on the node displacement of the optical surface of interest obtained in step 1, the smooth optical surface is reconstructed using the interpolation method and the least square method;

[0009] Step 3: Establish an optomechanical coupling ray tracing model;

[0010] Step 4: Perform dynamic ray tracing on the space optical remote sensor based on the optomechanical coupling ray tracing model to obtain the dynamic wavefront difference of the space optical remote sensor.

[0011] Aiming at the multidisciplinary influence of micro-vibration on the optical system of space optical remote sensor, the present invention combines multiple analysis methods to realize dynamic analysis of the optical system of space optical remote sensor, and realizes integrated analysis of the optical-mechanical system through opto-mechanical coupling. It is a very effective opto-mechanical integrated analysis method. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without exceeding the scope of protection required by the present invention.

[0013] Figure 1 A schematic diagram of a flow chart of a dynamic optomechanical coupling ray tracing method of the present invention;

[0014] Figure 2 A schematic diagram of a single ray tracing in an embodiment of the present invention;

[0015] Figure 3 Schematic diagram of an optomechanical coupling ray tracing model in an embodiment of the present invention. DETAILED DESCRIPTION

[0016] The optical system and mechanical system in current space optical remote sensors are often analyzed independently, while the dynamic optomechanical coupling ray tracing method provided by the present invention can couple the optics and structure together to implement performance analysis of the optomechanical system, and dynamically and efficiently analyze the impact of micro-vibrations on the imaging quality of space optical remote sensors. The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments in the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0017] In one embodiment, if Figure 1 As shown, the present invention provides a dynamic optomechanical coupling ray tracing method, the method comprising the following steps:

[0018] Step 1: Obtain the overall position relationship and surface elastic deformation of the optical system through structural dynamics analysis.

[0019] Finite element analysis software (such as Hypermesh and MSC Patran) is used to perform finite element modeling of the optical system, and a structural finite element model is established. Micro-vibration is applied as the input of the structural finite element model to obtain the structural dynamic responses of each component of the optical system under the action of micro-vibration, that is, to obtain the structural dynamic analysis results. The structural dynamic analysis results are then processed to finally obtain the node displacements of the optical surface of interest.

[0020] Step 2: Reconstruct the deformed optical surface.

[0021] Based on the node displacements of the optical surface of interest obtained through the structural dynamics analysis in step one, a suitable interpolation method such as the cubic spline interpolation method is selected to interpolate the node displacements, complete the node displacement approximation, and use the least squares method to fit the interpolated and reconstructed smooth optical surface.

[0022] Step 3: Establish an optomechanical coupling ray tracing model.

[0023] First of all, whether the light is refracted or reflected on the optical surface, we should focus on the intersection of the light and the optical surface and the corresponding direction of the light. Figure 2 As shown in Figure 1, the optomechanical coupled ray tracing model is based on linear algebra and geometric optics to calculate the path of a single ray in an optical system. The order in which the ray passes through the optical surface is determined in advance, and then the corresponding reference frame S is used to calculate the path of a single ray in the optical system. i-1 The intersection point m of the ray at the i-1th optical surface (surface i-1) is considered. i-1 and the associated light direction d i-1Then, the relative position S of the next optical surface (surface i) reference system is given i and the relative direction R i , the ray intersection points and ray directions must be from the reference system S i-1 Transform to reference frame S i . Figure 2 Medium i is the intersection point of the light rays at the i-th optical surface (surface i), d i is the direction of the refracted light, d i,refl is the direction of reflected light, r i-1 From the reference system S i To the intersection point m i-1 The vector, r i From the reference system S i To the intersection point m i According to the vector r i-1 and the light direction d i-1 Then we can get the intersection point m of the light on the i-th optical surface i , and can be based on the relative direction R i Get the direction of the light after refraction or reflection.

[0024] Then, based on the structural finite element model of the optical system, the relevant nodes are extracted during the single ray tracing process, the smooth optical surface reconstructed by interpolation in step two is calculated, the optical path under the reconstructed smooth optical surface is calculated, and the calculated optical path is compared with the optical path of the ideal optical path to obtain the optical path difference of the single light ray.

[0025] Finally, if Figure 3 As shown, large-scale ray tracing is performed to comprehensively obtain the wavefront difference of the entire light beam or the main light beam, thereby realizing "optical-structural" coupling.

[0026] Step 4: Based on the optomechanical coupling ray tracing model constructed in step 3, dynamic ray tracing is performed on the space optical remote sensor to obtain the dynamic wavefront difference of the space optical remote sensor, so as to analyze the influence of micro-vibration on the imaging quality of the space optical remote sensor.

[0027] The dynamic optomechanical coupling ray tracing method proposed in this embodiment uses finite element analysis software to perform structural dynamics analysis on the optical structure of the space optical remote sensor, obtains the node displacement of the optical surface of interest from the analysis results, selects a suitable interpolation method, and interpolates and reconstructs the smooth optical surface. According to the ideal adjustment relationship of the optical system and the mirror geometric surface, the wavefront characteristics of the ideal optical path are given; then, the structural finite element model of the reflector is used to extract the relevant nodes in the single ray tracing process, and the smooth optical surface is reconstructed by interpolation, and the optical path under the reconstructed surface is calculated and compared with the ideal optical path to obtain the optical path difference of a single light beam; finally, large-scale ray tracing is performed to comprehensively obtain the wavefront difference of the entire light beam (or main beam), realize optomechanical coupling, and perform dynamic optomechanical coupling ray tracing on the space optical remote sensor. Based on this method, the impact on the imaging quality of the space optical remote sensor can be better and more efficiently analyzed.

[0028] This embodiment aims at the multidisciplinary nature of the impact of micro-vibrations on the optical system of a space optical remote sensor, combines a variety of analysis methods to achieve dynamic analysis of the optical system of a space optical remote sensor, and realizes integrated analysis of the optomechanical system through optomechanical coupling. It is a very effective optomechanical integration analysis method.

[0029] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0030] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A dynamic optomechanical coupling ray tracing method, characterized in that: The following steps are involved: Step 1: Use finite element analysis software to perform finite element modeling on the optical system of the space optical remote sensor, apply micro-vibration as the input of the structural finite element model, obtain the structural dynamic response of each component of the optical system under the action of micro-vibration, and process the structural dynamic analysis results to obtain the node displacement of the optical surface of interest; Step 2: Based on the node displacement of the optical surface of interest obtained in step 1, the smooth optical surface is reconstructed using the interpolation method and the least square method; Step 3: Establish an optomechanical coupling ray tracing model; Step 4: Perform dynamic ray tracing on the space optical remote sensor based on the optomechanical coupling ray tracing model to obtain the dynamic wavefront difference of the space optical remote sensor.

2. A dynamic optomechanical coupling ray tracing method according to claim 1, characterized in that: The optomechanical coupling ray tracing model performs the following steps: Step 31: Calculate a single ray path in the optical system; Step 32: Based on the structural finite element model of the optical system, extract relevant nodes in the single ray tracing process, calculate the optical path under the smooth optical surface reconstructed in step 2, and compare the calculated optical path with the optical path of the ideal optical path to obtain the optical path difference of the single ray; Step 33: Perform large-scale ray tracing to comprehensively obtain the wavefront difference of the entire beam or main beam coupled by the optomechanical system.

3. A dynamic optomechanical coupling ray tracing method according to claim 1 or 2, characterized in that: The finite element analysis software is Hypermesh software or MSC Patran software.

4. A dynamic optomechanical coupling ray tracing method according to claim 1 or 2, characterized in that: The interpolation method is a cubic spline interpolation method.

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