偏振激光在大气传输中的退偏研究

Depolarization Characteristics of the Polarized Laser in Atmosphere

用蒙特卡罗方法对偏振激光在浓雾和弱雾中的传输特性进行建模。当偏振激光波长相同时,分别分析计算了偏振激光在浓雾和弱雾中不同雾气粒子半径下传输的退偏特性。并比较了偏振激光在不同传输距离时,其偏振角的变化情况。仿真结果表明:1)雾粒子半径较小时,偏振角变化最大的主要集中在后向,而前向整体上的偏振角很小,球形粒子的单次前向散射偏振角是不变的;2)随着雾粒子半径的增大偏振角出现了越来越多的复杂旁瓣;3)光散射偏振角随着光传输距离的增加而增大,并且在浓雾中传输比在弱雾中传输的退偏大。

A Monte Carlo algorithm is presented to model characteristics of polarized laser in thick fog and thin fog media. When the wavelengths of polarized laser are equal, the depolarization characteristics of the polarized laser are analyzed separately in the different fog particle radii. And the changes of polarizing angle are compared in the different transmitting range. The simulation result shows that, 1） when the granule radius is small, the biggest changes of backward polarization angle are mainly centralized, and the changes of all forward polarization angles are very small. The forward scattering polarization angle of a single sphere granule is invariable; 2） more and more complex side lobes of polarization angles appear with the increase of the fog particle radius; 3） the diffused light polarization angles increase with the increase of optical transmission distances, and the depolarization angles of laser in thick fog are bigger than those in thin fog.