As an important optical component, the mirror is an important part of the tracking camera. The rapid prototyping technology of 3D printing is becoming more and more mature, and its application scope is more and more extensive. Silicon carbide material has excellent physical properties such as high elastic modulus, specific stiffness and thermal stability. To meet the practical requirements of high stiffness, light weight of a special-shaped mirror, topology optimization was adopted to design the mirror structure. The objective is maximizing the weighted superposition of the structural stiffness and the first-order natural frequency;the constraint function is an upper bound on the volume fraction. After optimized design, the mirror with a special shape back was obtained. A feasible CAD model was formed by adjusting the position and thickness of the stiffener. The self-weight deformation and natural frequency of the model were analyzed by commercial finite element analysis software and the results show that the maximum RMS value of the mirror under 1g gravity condition is 14.6nm, and the first-order natural frequency is 2037Hz. Then the 3D printing additive manufacturing technology was used to fabricate the special-shaped mirror. After adjusting ,when the optical axis of the mirror and the ground into an Angle of -40°, 0°, 40°and 80°, the mirror surface accuracy meets the requirements.
Remote sensing satellite in low earth orbit is a kind of spacecraft developed to meet the needs of high-resolution imaging observation, rapid response to emergency earth observation and disaster image monitoring. In this paper, a finite element model of a remote sensing satellite camera with a diameter of 800mm thermal protection door (thermal door for short) was established. The topological optimization design technology is used to design the thermal door structures with high-reliability, high-strength and ultra-light. After optimization, the weight of thermal door is 4.5Kg. The finite element simulation analysis is carried out on the thermal door, and the analysis results show that the thermal door meets the harsh mechanical conditions of a satellite platform. The mechanical test of thermal door was carried out, and the test results match the simulation analysis results. After the mechanical test, the thermal boundary and vacuum conditions in orbit were simulated in the thermal vacuum experiment tank, and the thermal door’s opening and closing tests were carried out. The thermal door’s opening/closing time, opening/closing speed, structural stability and positioning accuracy meet the index requirements. This thermal door has been developed and delivered to the satellite. The research results of this paper have a certain reference value for the design of thermal door for remote sensing satellite cameras with low power consumption and high temperature control requirements..
With the development of remote sensing satelite, the infrared and visible light parts have been integrated gradually. As the internal vibration source, the jitter of cryocooler has more and more influence on the imaging quality.At present the study of cryocooler jiiter mostly focus on the inside of the camera.We usually ignore the platform ,regard camera as a separate part,then analysis the displacement between the optical lens. But the platform and the load has the coupling relationship.The flexible platform changes the boundary of the camera.At this time,the rigid motion of the camera becomes dominant. separate research will bring bigger deviation .So two models were created which called the separated camera model and the coupled platform-camera model, then the micro-vibration transmission from the cryocooler to the optical mirrors in both cases was analysised and the relationship between coupling frequency and response size was obtained. by the way, the optical axis jitter and the deviation of the optical alignment caused by cryocooler jitter in the time domain was analysised , through optical sensitivity matrix, the change of line of sight was obtained and then the decline of MTF and the image distortion was obtained. The result shows that when the cryocooler worked, the image motion of the camera in the integration time is 0.25pixels,and the MTF is reduced by 2.5%,but the image distortion can reach 0.52pixels.
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