Analysis and protection of stray light for the space camera at geosynchronous orbit

Stray light is the general term for all non-normal transmission of light in the optical system. The influence of stray light is different according to optical system's structure. Large area array camera at geosynchronous orbit is facing more serious influence of stray light, especially for the small incident angle of sunlight on the system. It is in dire need of a detailed analysis of stray light of the basic shape of the optical system. In the paper, the influence on the camera used in space from stray light and the necessity to eliminate stray light are presented. The definition of the stray light coefficient and PST(point source transmittance) is briefed. In Tracepro, analysis of the impact of sunlight incident was made at different angles on the space camera, in the case of stray light factor for the quantitative evaluation. The design principle of the inside and outside hood is presented for the R-C (Ritchey Chretien) optical system. On this basis, in order to reduce stray light interference for the space camera, the primary and secondary mirror's hoods were designed. Finally, when the incidence angle of sunlight is more than 3 degrees incidence on the space camera, the coefficient of stray light is less than 2%. It meets the engineering requirements.