快速空间测角系统中偏振像差的分析与研究

快速空间测角系统需要在一定的平移范围内均能实现测量功能,这就要求光束在接收单元具有一定的覆盖面积.受器件尺寸所限,选择对入射光束进行扩束,然而非正入射光经过系统会产生偏振态变化,存在偏振像差,引起测量误差.本文通过采用偏振光线追迹的方法,结合电磁场的边界条件,对快速空间测角系统中一定方位及入射角范围内的光束通过偏振棱镜后出射光束的偏振态变化与分布进行了理论研究及仿真分析;并通过搭建实验平台,利用平移接收单元来模拟不同的入射方位及角度变化.根据实验值与仿真结果的对比分析,得出在方位角为0o时,测量误差较小,在方位角为90o时,测量误差最大,且随平移距离(即入射角)的增大,测角误差增大.验证了偏振像差的存在对系统测角带来的影响及理论分析的正确性,并提出了改进措施.所得研o究结果对优化系统结构并进一步提高系统性能具有一定的指导意义.

Analysis and research of polarization aberration in rapid space angle measuring system

The precise angle measurement and transmission technology have been widely used in the precision measurement, aerospace, military, biomedicine and other devices, which are based on the polarized light and magneto-optical modulation. This method has the characteristics of no rigid connection required, long distance transmission, high precision, etc. However, the azimuth information measurement method needs the assistance of complex servo tracking system according to the orthogonal extinction principle of polarization prism, meanwhile, the measurement time is longer, which reduces reliability and reaction sensitivity of the system. In order to improve the measurement accuracy and fast response capability of the system, a fast space goniometry method is proposed through the Wollaston prism polarizing beam splitter, with which the azimuth is directly calculated according to the two light intensities. The measurement time can be shortened, and the accuracy is improved by the use of magneto-optical modulation technology. The rapid space angle measuring system needs to realize the measurement function in a certain translation range, which requires the beam to have a certain coverage area in the receiving unit. However, the system is limited by size and volume of the device; we can only choose to expand the incident beam. Therefore, when the beam is incident onto the receiving unit, some incident angle and azimuth, that is, non-vertical incidence will be produced. However, the polarization of the non-vertically incident light passing through the system will change and polarization aberration exists, which will lead to measurement error. In this paper, the beam passes through the polarizing prism in a certain range of azimuths and incident angles, and the polarized light tracing method and the boundary condition of the electromagnetic field are used to study and simulate the polarization change and distribution of the outgoing beam. The changes of different incident azimuths and angles can be simulated through the translation of receiving unit, and the azimuths can be measured indirectly by using self-collimation theodolite and right angle prism. By comparing the measured azimuths under the translational and centering conditions, the influence of polarization aberration on the angle measuring system and the correctness of the theoretical analysis are verified. It is concluded that when the azimuth angle is 0°, the measurement error is small; when the azimuth is 90°, the measurement error is largest, meanwhile the measurement error will increase with the translation distance becoming longer (i.e., the incident angle). According to the comparison between the experimental data and the simulation results, the existing problems are pointed out, and the corresponding improvement measures are proposed. The results of this work have some significance in guiding the optimization of the system structure, and the further improvement inthe performance of the system.