可见光全天时遥感相机光学系统设计

Optical system design of remote sensing camera with visible light all-day

由于微光遥感可在夜间和晨昏时段等低照度条件下对地物进行探测,该遥感相机利用微光遥感与传统可见光遥感进行互补,实现可见光波段全天时对地观测。考虑系统长焦距(500 mm)、大视场(5°×2°)、大相对孔径(F数为3.8)、小型化、高光学效率等各方面因素,该遥感相机最终采用离轴三反结构形式,采用双探测器共光路、分视场形式实现微光、可见光探测器同时成像。对光学系统设计和成像质量进行了详细分析,传统可见光波段各视场MTF优于0.4@200 lp/mm,微光可见光波段各视场,MTF优于0.75@77 lp/mm,MTF接近衍射极限,结果表明:根据光学载荷研制发射流程,从加工、装调、一次调焦和不调焦四个过程详细分析了系统公差,给出了公差分配结果。此外,对该光学系统的可扩展性进行了分析说明。

Because micro-light remote sensing can detect ground objects under low illumination conditions such as nighttime and twilight, this remote sensing camera uses micro-light remote sensing to complement the traditional visible light remote sensing to achieve observation in visible light all-day long. Considering the system′ s long focal length(500 mm), large field of view(5° ×2°),large relative aperture(F number 3.8),miniaturization and high optical efficiency, this remote sensing camera used off-axis three-mirror system structure and common light path for double detectors, subfield of view to achieve simultaneous imaging from micro-light and visible light detectors. The optical system design and imaging quality of the optical system of the camera were analyzed in detail. The results show that the modulation transform function(MTF) of traditional visible light fields of view are more than 0.4 at the Nyquist frequency of 200 lp/mm and the MTF of micro-light fields of view are more than 0.75 at the Nyquist frequency of 77 lp/mm and the MTF is close to the diffraction limits. Based on development and launch processes of optical load, system tolerances were analyzed from the four processed of machining, alignment, prima ry focusing and non-focusing, and the result of tolerant assignment was given. In addition, the extensibility of the optical system was illustrated.