The infrared focal plane assemblies (FPA) are usually integrated in ambient temperature, and operate in 80K~40K. Mechanical cryocoolers are typically used to provide the cryogenic temperature. The mechanical designs of FPA have to take a variety of constraints into consideration, such as thermal stresses, temperature uniformity of detectors, vibration from cold fingers, stray light of dewar (optical stops), flatness of the detector arrays, thermal insulation, severe vibrations during launch and optical alignment stability. For large format focal plane assemblies, the stress and deformation caused by thermal mismatch of HgCdTe detector chip, silicon readout integrated circuit (ROIC) and mounting structures become worse. This paper presents an innovative thermo-mechanical designed for Visual and Infrared Multispectral Imager (VIMI) onboard GaoFen-5 satellite. It proposed a symmetrical sandwich configuration to ensure the flatness of detector arrays, and a flexure adaptor plate module made of molybdenum-copper to mitigate thermal stress of detectors and Low Temperature Co-fired Ceramic (LTCC). Finally, a series of mechanical and thermal tests were conducted to verify the reliability of the thermo-mechanical design of FPA.
In order to obtain reflector supporting structure with high stiffness and thermal stability, a “2-2-1-1” kinematic supporting structure is designed for a 350mm mirror of space remote sensor. Firstly, the kinematic principle of the “2-2-1-1” supporting structure is studied, and the dynamic model of the “2-2-1-1” supporting structure is deduced, the relationship between the supporting stiffness of the mirror assembly and the parameters of the length, diameter and span of the ball-end supporting rod is given. According to the relationship between the supporting stiffness of the mirror assembly and the length and diameter of the supporting rod, a “2-2-1-1” supporting structure of the mirror assembly is designed. The mechanical simulation of the design results is carried out by means of finite element analysis, and then the test of the actual supporting structure is carried out. The experimental results show that the RMS value of the reflector supported by “2-2-1-1” supporting structure is better than λ/40(λ=632.8nm), The fundamental frequencies of the components in three directions are respectively 231Hz, 319Hz and 365Hz, it is close to the results of finite element analysis and theoretical calculation. The rationality of the designing of the “2-2-1-1” supporting structure of the reflector is proved, which meets the imaging requirements of the space remote sensor.
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