激光雷达偏振成像主要是利用不同目标散射光偏振度的差异来实现对目标成像的。由于大部分光学系统都存在消偏振效应,因此系统自身的消偏振问题在成像过程中必须考虑。根据近轴理论和消像差的要求设计出卡塞格伦望远镜的几何结构,应用琼斯理论、光波的相干矩阵和菲涅耳反射理论对空气和卡塞格伦望远镜的交界面进行了消偏振分析,并使用Matlab软件仿真了卡塞格伦望远镜在镀金属反射膜前后,反射光偏振度在望远镜径向直径上各点的变化曲线。根据仿真结果可以看出偏振成像系统中使用的卡塞格伦望远镜在镀铝金属反射膜时其消偏振效应在成像过程中可以忽略。

The lidar polarization system realizes imaging for targets by the polarization differences of light scattered by the different targets. Because there exist the depolarization effects in a majority of systems, the depolarization problem of system itself must be considered in the process of imaging. According to the adaxial theory and requirement of optical aberration, the geometrical structure of Cassegrain telescope is designed. Then the depolarization behavior of the interface between air and reflecting mirrors of Cassegrain telescope is analyzed by using Jones formalism, coherent matrices of optical waves and law of Fresnel reflection. And the polarization degree of light is emulated, which is reflected from every point of reflecting mirror coated with and without thin film, relative to the diameter of Cassegrain telescope through the help of Matlab software. Based on the simulation, it is deduced that the polarization degree of light reflected from the telescope overcoated with aluminium film in the imaging system can be ignored in the imaging process.