利用消杂散光的偏振光技术提高光学读出红外成像检测灵敏度

A technology for eliminating stray light in optical readout of FPA

在基于刀口滤波技术的光学读出的非制冷红外成像技术中,光学元件的反射会在CCD靶面引入杂光光斑,使得检测到的光强信号中FPA的像所占比例降低,因此降低了光学检测灵敏度.采用偏振光学读出系统,即在光路中添加偏振片、四分之一波片,利用对透射光和反射光的偏振方向有选择的偏振分光棱镜代替原有分光棱镜,用偏振光原理消除光路中光学元件的反射杂散光,使FPA像在CCD靶面接收到的光强中所占比例大幅度增加,进而提高光学检测灵敏度.偏振光路检测实验结果显示,检测灵敏度比非偏光实验提高了约47%,与理论分析值一致.

In the uncooled optical readout infrared imaging technology based on knife edge filter, the reflection of the optical elements bring in stray light spots in the CCD target surface. It makes the proportion of FPA image in the detected light intensity signal reduced, thus the sensitivity of optical detection is reduced. A polarized optical readout system was proposed. Polarizers and a quarter wave plate are added to the system. The polarizing beam splitter is used to replace the original beam splitter. The reflected stray light of the optical components in the optical path is thus eliminated. The proportion of the EPA image received in the CCD target surface substantially increased, so the optical detection sensitivity is enhanced. The polarized optical readout infrared imaging experiment result showed that the detection sensitivity increased by about 47% than the non-polarized system, which is close to the theoretical value.