By reducing the working temperature of opto-mechanical structures, the infrared system signal to noise ration can be effectively improved. Normally, structures close to the focal plane radiate more noise. Signal to noise ration can be improved by cooling the opto-mechanical in front of the focal plane. In this paper, an infrared lens working at both room and low temperature is designed. The first four lenses work at room temperature and the other three lenses close to the focal plane work at 200K. The cryogenic lens is cooled by space pulse tube cryocooler. UG TMG thermal analysis results show that the working temperature of each lens meets the requirements, and the temperature gradient of each lens is less than 0.2K. Modal analysis results show that the first modal frequency is 97.2Hz. The finite element analysis results show that the maximum stress of the structure is 227.8MPa, which is far less than the allowable stress of TC4. Thermal-structure-optical analysis show that the system MTF has a small decrease from root temperature to working temperature. By adjusting the position of the focal plane, the system MTF can recover to the design results. The results of the vacuum experiment show that the working temperature of the lens is close to the simulation results. The wavefront error is measured both at room temperature and working temperature. The average wavefront error is 0.060λ (λ=632.8nm) at working temperature and 0.070λ at room temperature. Experiment results verify the correctness of the thermal design and opto-mechanical design.
The imaging quality of the remote sensing camera is directly related to the thermal design of CCD. The cycle average thermal control power required by CCD is 1/3 of the whole remote sensing camera under traditional temperature control solution. with the resolution of the remote sensing camera is increasing. Thermal control of CCD components could be a bottleneck in the thermal control of the camera. According to the temperature control requirements of CCD devices , the temperature control scheme of CCD using semiconductor and phase change heat pipe is proposed for the first time. Simulation analysis and experimental verification are carried out on the key components of the temperature control scheme .based on the simulation analysis and experimental verification of key components, the system simulation model was established ,and the relationship between the phase transition temperature and the area of the radiator is obtained by simulation. System simulation results show that the thermal control scheme can meet the requirements and the temperature of the CCD is between 18℃ and 21.5℃. The radiator area is only 16% of the traditional program. The cycle average power consumption under high temperature condition is only 5% of the traditional scheme. the cycle average power consumption under low temperature condition is only 16% of the traditional scheme. the temperature stability of the CCD during imaging period can be improved one order higher by adjusting the starting strategy of the remote sensing camera to ±0.2℃.
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