Several factors affecting self-thermal radiation of cryogenic infrared optical system

In cryogenic infrared optical system, any inner component of this system above absolute zero will emitt infrared radiation. These radiation, striking detector surface through transmitting in optical system, makes self-stray radiation of infrared system. This self-stray radiation is dominant stray radiation in cryogenic infrared system, and it is a key factor of reducing image quality of cryogenic infrared system. How to suppress self-stray radiation becomes a critical work in the whole design process of cryogenic infrared system. Take a space remote sensor as an example, distribution change of self-thermal radiation on the detector surface when the space remote sensor under different temperature, emissivity or surface state is presented in this paper. Phenomena of self-thermal radiation in optical system is also researched from two aspects of self-radiation of emitting sources and transmission of thermal radiation in optical system. Consequently, several key factors of making thermal radiation of detector surface change are found. Therefore, corresponding measures of suppressing thermal radiation are proposed. And self-stray radiation of cryogenic infrared optical system has been effectively suppressed and the performance of the space remote sensor has been ensured within its technical requirement.