Optical system design of multi-spectral camera for space debris

In order to detect the Space debris, a multi-spectral camera for Space debris was proposed. The multi-spectral camera was consisted of visible camera, long-wave infrared (LWIR) camera and mid- wave infrared (MWIR) camera. Three cameras used the primary mirror and secondary mirror together, including correction lens in every camera in order to balance aberration. The focal length was 1000 mm and field of view was 1.2° for visible camera, and the focal length was 250 mm and field of view was 2.75° for LWIR camera, and the focal length was 500 mm and field of view was 1.38° for MWIR camera. Some measures were taken to make sure the less degradation of MTF for thermal distortion, such as a kind of material with good thermal property as mirror substrate to reduce surface distortion. The modulation transfer function(MTF) of three cameras in condition of 20±5°C was analyzed, which showed a good result for user's requirement.