Design Of Supporting Structure For The Large-scale Stereo-mapping Shrunken Space Camera

With the development of stereo-mapping camera technology, the design and processing of the stereo-mapping camera is more and more difficult because of the more and more strict requirements to the key index of the optical system. The off-axis three-mirror optical system has the great advantage of making the space camera shorter in the application process. On the one hand, the off-axis three-mirror optical system could be used widely because of the unique advantages. On the other hand, the design of the supporting structure for this optical system is a generally acknowledged difficulty.The optimization design method based on dynamic load of the supporting structure for the off-axis three-mirror optical system applied in the stereo-mapping space camera was studied in this paper. In order to meet the requirements on mapping accuracy and the weight of the camera, the topology optimization design theory to minimize the random response was introduced to the processing of designing the supporting structure for the stereo-mapping space camera. The main work is as follows:1. The optical systems of the stereo-mapping space camera and its optical lenses were analyzed. The same off-axis optical system was used for these two lenses. The design of the supporting structure for these two lenses was the key to the design of the supporting structure for the stereo-mapping space camera. The requirements to supporting structure for this space camera were given.2. According to the characteristics and requirements of this optical system, the form and the materials of the supporting structure were determined. According to the design requirements of the space camera, a topology optimization design to minimize the random response was conducted, which could provide the references to the design of the supporting structure for other space cameras. Based on the result of the topology optimization design, a dynamic dimension optimization was conducted. Then a supporting structure was obtained. The dynamic analysis and the thermal analysis were conducted. It shows that this supporting structure could meet the major requirements of the key index.3. The sine sweep test of 0.1g and the random vibration test of 2gRMS were carried out to this supporting structure for the camera. The difference between the secondary mirror’s response curve under sinusoidal scan before the random vibration test and that after the random vibration test is very small. It shows that the fundamental frequency reaches 181.4Hz and the supporting structure has a good quality of stability. The random response of the secondary mirror in optical axis is controlled effectively. The maximum error between the data from the finite element analysis and the data from test is 6%, which meets the requirements to engineering analysis accuracy. The correctness of the design theory of this supporting structure and the rationality of the structure are Indicated.4. Various important parameters of the camera were detected. The intersection angle of this stereo-mapping space camera is 22.6023, and the relative deviation is about 0.01%. The modulation transfer function of the optical lenses is all more than 0.1 in the frequency of Nyquist. The relative distortion of the two optical lenses is all about 0.05%. All kinds of design indexes could be met, which shows that the supporting structure of this camera has a good rigidity and stability.The design method proposed in this paper could be used to control the random response of the space cameras. The optimization strategy of this trussed supporting structure could provide some references to the other space cameras with the same type.