为了研究多次散射效果下红外辐射在雾中的传输衰减特性, 基于Mie散射理论, 计算了1.064 μm、3.8 μm和10.6 μm激光在平流雾和辐射雾中的消光参量和多粒子散射相位函数.利用Monte Carlo法建立了辐射传输模型, 分析了多次散射效应下接收屏、能见度和传输距离对透过率的影响, 并与Lambert-Beer定律计算结果进行了比较.结果表明: 当能见度和传输距离均为1 km时, 1.064 μm激光在平流雾中的接收屏粒子数随接收屏边长的增加而显著增加; 相同的能见度和传输距离下, 激光在辐射雾中的衰减小于在平流雾中的衰减; 10.6 μm激光在平流雾中具有很好的传输性; 当粒子散射能力越强、前向散射概率越大时, 多次散射对透过率的贡献越明显; 激光在雾中的传输衰减特性不仅与消光系数有关, 还与散射系数密切相关; 能见度和传输距离存在最佳组合, 使得此传输条件下多次散射对透过率的贡献最大.

In order to study the transmission characteristics of infrared radiation in fog under multiple scattering effect, the extinction parameters and multi-particle scattering phase functions of 1.064 μm, 3.8 μm and 10.6 μm laser in advection fog and radiation fog were calculated based on Mie theory. A radiative transfer model was established by Monte Carlo method. The effects of the size of the receiving screen, the visibility and the transmission distance on the transmittance were analyzed, and the results were compared with Lambert-Beer law. The results show that when the visibility and transmission distance are both 1 km, the number of particles on the receiving screen of 1.064 μm laser in advection fog increases significantly with the increase of receiving screen side length. The attenuation of laser in radiation fog is less than that in advection fog under the same visibility and transmission distance. 10.6 μm laser has good transport properties in advection fog. The stronger the scattering ability and the higher the forward scattering probability, the more obvious the contribution of multiple scattering to the transmittance. The attenuation characteristics of laser transmission in fog are related to extinction coefficient and scattering coefficient. There is an optimal combination of visibility and transmission distance which maximizes the contribution of multiple scattering to the transmittance.