用几何光学方法计算雨滴散射光偏振度

Computing Polarization Degree of Scattered Light on Raindrops with Geometrical-Optical Method

在几何光学范畴内得出雨滴散射光平行与垂直振动强度和偏振度表达式,计算了波长为0.5847 μm的雨滴散射光偏振分布.结果表明：散射角在55°～75°范围内,为明显的折射式偏振区,偏振度在0.2～0.3之间;散射角为82°～100°时,是强反射式偏振区,偏振度在0.8以上,最高达0.95;散射角100°～142°时,偏振度变化迅速,形成了尖锐的凹点,其偏振度与相应方向虹、霓的偏振度接近.用几何光学方法计算雨滴散射光偏振度,不影响计算精度,运算量明显减小.

The expressions of the parallel and vertical vibration intensity and the polarization degree of scattered light on raindrops in the range of geometrical optics are presented, and the polarization distribution of scattered light on raindrops at the wavelength of 0. 5847μm is computed. The results indicate that the scattering-angle range of 55° - 57° is obviously the refracting-type polarization area with the polarization degree being in 0.2 - 0.3; the scattering-angle range of 82° - 100° is the reflecting-type polarization area, with the polarization degree being above 0.8 - 0.95; and when the scattering angle is in 100° - 142°, the polarization degree changes rapidly, forming an obvious concave point, close to that of rainbow in the corresponding direction. To compute the polarization degree of scattered light on raindrops with the geometrical-optical method does not affect computation precision with an apparently reduced computation load.