除了具备作用距离远、可全天候工作、隐蔽性好等传统红外强度成像的优点外，基于目标与背景偏振特性差异的红外偏振成像技术能够有效减小背景干扰、抑制背景杂波、增强图像对比度、提高信噪比，应用前景广阔。为了有效抑制空中和海面目标探测过程的背景杂波干扰，增强雾、霾和烟尘以及小温差、低照度和复杂背景环境下的目标探测能力，采用分孔径同时偏振成像方式，完成了焦距为240 mm的四通道制冷型分孔径中波红外偏振成像光学系统的设计。利用蒙特卡洛法进行了公差分析，保证了光学系统加工和装调精度的合理性。像质分析结果表明，光学系统的MTF接近衍射极限，各类像差得到了有效校正，成像质量良好。通过冷反射分析验证了冷像对所设计制冷型红外光学系统成像质量的影响程度。此外，最终完成的光学系统结构紧凑，透过率高，避免了非球面的使用，具有良好的加工和装配工艺性。

In addition to the advantages of traditional infrared intensity imaging, such as long detection distance, all-weather working and good concealment, infrared polarization imaging technology based on the difference between the target and background polarization characteristics can effectively reduce background interference, suppress background clutter, enhance image contrast, improve signal-to-noise ratio, and has broad application prospects. In order to effectively suppress the background clutter interference in the process of air and sea detection, enhance the target detection ability in fog, haze and smoke, as well as the backgrounds of small temperature differences and low illumination, the design of a four channel aperture sharing medium-wave infrared polarization imaging optical system with a focal length of 240 mm was completed. Tolerance analysis was carried out by using Monte Carlo method to ensure the rationality of the precision of optical system processing and assembly. The results of image quality analysis show that the MTF of the optical system is close to the diffraction limit, aberrations have been effectively corrected, and the imaging quality is good. The influence of Narcissus effect on the imaging quality of the cooled infrared optical system was verified by Narcissus analysis. In addition, the optical system proposed has a compact structure and high transmittance, avoiding the use of aspheric surfaces, and has good processing and assembly technique.