Study On Support And Adjustment Of Large-diameter Mirrors On Low Temperature Condition

With the development of the space remote sensor, the support of large aperture mirrors and the technology of mirror installing has been a heated issue among the researchers. Due to the surface of the large aperture mirror will be deformed under gravity and low temperature and may result in the worse of imaging quality. According to the working environment and the surface accuracy requirements, the research has designed a set of supporting and adjusting mechanism to reduce the deformation of the mirror. The research determines the basic dimensions of the mirror, Finishes the lightweight design of mirror, designs the support structure of the mirror and completes the adjusting mechanism of the mirror. At last, the research analyzed the surface deformation of the mirror with Ansys. The research contents can be divided into the following parts.Firstly, based on the outcome of the off axis three mirror reflective system, the research get the thickness of the mirror through the empirical formula, considering the working environment, the research confirms the material of the mirror for Si C. Finish the lightweight design of the mirror and comparatively analyze the surface deformation under the various support methods with the tool of Solidworks Simulation, and then determining the best support method.Secondly, comparing and analyzing the advantages of the support structures of the large aperture mirrors in the world,the research makes design of the support structure according to the deformation requirement of the mirror. Introduce the mechanical properties and structure characteristics of Flexible Hinges in details and determine the support form of 9 point Kindle support based on Flexible Hinges. Calculate the size of the supporting part properly. Make strength check on the connected pair which connected the support structure and the mirror seat.Thirdly, the research introduces the principle of micro displacement of the ball hinge rod and the working principle of ball screw briefly. According to the design requirement of the mirror system, the adjusting mechanism should consists of two parts, one is two degrees of freedom rotating mechanism, the other is ball screw moving platform. Determine the size of the lead screw, the step motor and the ball hinge rod according to the working conditions and design parameters. Finally, analyze the accuracy of the mirror system.Finally, use the finite element software Ansys Workbench 12.0 to simulate the large aperture mirror system on low temperature. The analysis can be divided into three parts, one is the influence of gravity on the surface of the large aperture mirror, another is the influence of 90 K temperature on the surface of the large aperture mirror, the third is the deformation of the surface of large aperture mirror under the combined influence of gravity and 90 K temperature. The results of the analysis can meet the requirements of the surface deformation, which verify the rationality of the system.