Stray light simulation and suppression of high-resolution simultaneous polarization imager

A high-resolution simultaneous polarization imager based on off-axis three-mirror telescopic objective detects polarization information to enhance contrast and identify target. Stray light can increase system noise, reduce image contrast, and affect imaging quality. It is necessary to analyze and suppress stray light in order to ensure the polarization measurement accuracy of the instrument. The three-dimensional solid model and optical properties of the instrument were established by stray light analysis software Tracepro. The stray light of channel 1 was simulated and analyzed. The important surface of the system and the first-order stray light paths were found through forward trace and backward trace. The main baffle and vane, secondary mirror baffle and third mirror light barrier were designed by using CAD drawing software. Then the PST (Point Source Transmittance) curve of stray light is given under off-axis angle is within ± 50 °. When the off-axis angle is  30 °, PST is less than 10-10. The VGI (Veiling Glare Index) is 1.47%, which was obtained by fitting the PST curve and integrating. The influence of the VGI on the polarization accuracy was 0.020@p=0.3. The results show that the stray light suppression system have obvious effects, and the influence on the polarization accuracy is acceptable.