Stray light analysis of catadioptric long-wavelength infrared optical system

A hood for the system is designed for the characteristics of the catadioptric long-wave infrared optical system. The optical mechanical structure model of the system was established in the stray light analysis software Tracepro. The external stray light is analyzed and calculated by ray tracing, and the PST curve of the system is given. According to the thermal noise of the detector and the influence of solar stray light, the requirements of the system PST are proposed. Calculated the stray light of the sky background, the relationship between the thermal noise of the radiation surface of the system reaching the detector target surface and the temperature is given when the temperature range is 260K~320K. The analysis results show that when the off-axis angle is greater than the critical angle of incidence of the sun, the PST value is less than 10 -8 , which meets the requirements. The heat radiation inside the system also gradually increases with the increase of temperature. To realize the background limit detection of weak targets, the system needs to be cooled.