Research And Design On The SIC Primary Mirror Of A Space Visible Camera Based On Finite Element Method

With the development of the space optical detector technology, the high-resolution optical system is necessary. The primary mirror is the key to the resolution of space optical system, which demands the size of primary mirror bigger and bigger for the space cammer. Increasing in diameter, however, lead to the following technological problems: the deformation of the primary mirror caused by selfweight, the heat-swell deformation of the mirror face caused by the change of the environment temperature, the mirror grads, the cost of launch will all increase. So, the weight of middle and large primary mirror must be reduced by excision the part of the mirror which doesn't take part in imaging. Also as the largest optical element, the primary mirror is the key part of the space optical system, its surface figure affects the imaging quality directly and the space thermal environment is complex. So we must analyze the imaging quality change of the optical system caused by the space thermal environment.and bring forward the request of the temperature control.This paper summarizes the development of primary mirror's lighten method.Then, based on the analysis of the material, SiC is chosen as the material for the primary mirror. According to the machining technic in china, the open-back style of primary mirror was chosen. Considering the design requirements of the primary mirror, the static and dynamic properties of the SiC mirror with the sector, the triangle and the circle structure are analyzed. Mirrors with the sector structural form which has the best combination property are chosen to do the optimum analysis. Some structure parameters having significant effect on the mechanical properties and the mass of the mirror, such as thickness of the mirror, the faceplate and the rib, are used as the design variables. Finally, we get a mirror style which has just 30.4% weight of a solid style, and completed with the other mirror style use the center position fixup style.we got a conclusion that the mirrors with the sector structural are better than the center position fixup style.This thesis also analyzinged the imaging quality change of the optical system caused by the space thermal environment .Under different orientation temperature grads, there exist different deformation of the mirror face, which wreck the quality of image intensively. If we hope to get a wonderful image quality, we must control the axial temperature different and control the radial temperature different in a reasonable confine.