一种双波段成像系统的红外通道杂散光分析

Stray light analysis on infrared channel of dual-band imaging system

为全面分析杂散光对红外系统成像质量的影响,设计了可见波段0.4μm^0.7μm、红外波段3μm^5μm,视场角均为2.27°×2.27°的共孔径成像光学系统。分析了杂散光来源,分别研究了带内与带外杂散光对其红外通道成像质量的影响。对于带内杂散光,设计了消杂光结构,采用FRED软件模拟分析了带内杂光抑制能力,结果表明:带内杂散光得到较好抑制,其鬼像影响可忽略不计,太阳杂散光抑制水平PST达到设定的10-8阈值量级。对于带外杂散光,主要研究了1.064μm和2.6μm两个波长带外激光对红外成像系统的影响,并利用有限元仿真计算,结果表明:系统反射镜温升达到703K时,向外发出较强带内红外辐射,到达像面的辐射功率为0.195mW,可对红外成像面造成强烈噪声干扰。

To analyze the effect of stray light on infrared imaging system comprehensively, a common aperture imaging optical system was designed for both visible band（0.4 μm-0.7 μm） and infrared band（3 μm-5 μm） while the field of view is 2.27°×2.27°. By analyzing the stray light source, the effect of in-band stray light and off-band stray light on imaging quality of infrared channel was studied respectively. The structure of the hybrid light was designed for in-band stray light and the suppression capability was simulated and analyzed by FRED optical software. According to the result, the in-band stray light can be suppressed well, the ghost impact is negligible, and the point sources transmittance （PST） of solar stray light suppression level reaches the set threshold level of 10-8. For off-band stray light, the influence of 1. 064 μm and 2.6 μm infrared laser on infrared imaging system was mainly studied by finite element method. Results show that the in-band infrared radiation can be generated strong when the temperature of system mirror rises to 703 K and the radiation power to the image plane reaches 0. 069 mW, which can cause strong noise interference on the infrared imaging surface.