激光经大气传输到达接收设备的整个过程中，透过大气的能力较弱，易被大气中的分子、气溶胶、烟尘等散射和吸收，造成激光信号的衰减，探测能力下降，使得到达接收设备的激光能量减小，对激光通信的工作性能造成影响，因此研究激光在复杂大气环境中的传输特性具有重要的意义。本文主要研究降雨和雾环境对激光信号造成的散射和衰减特性。 　　　本文对降雨和雾的物理特性做了比较详细的阐述，微米波段的激光在大气中传输，主要涉及到的理论是Mie散射理论，仿真分析了衰减效率因子随散射微粒尺寸的变化特征，同时仿真分析了微粒散射光强空间分布规律。本文根据雨雾特性和Mie 散射理论：1)推导出了降雨环境中常用雨滴尺寸分布模型的衰减理论计算，结合实际工程中所使用的经验模型，用Matlab仿真分析了M-P、Joss和两个经验模型的雨滴衰减系数随降雨率的变化关系，得出激光传输在小雨中的衰减要比大雨时的衰减大；2)基于单个雾滴的散射特性，给出了在雾环境中造成激光衰减的常用经验模型，用Matlab仿真分析了平流雾和辐射雾在不同模型之间的衰减特性，得出激光波长越长时，其衰减系数越小，当能见度大于500米时，各模型之间的衰减相差不大，但能见度小于500米时，他们之间的差别随能见度的降低越来越大，此时需要考虑多次散射。本文还讨论了激光在雾中斜程传输时对激光造成的衰减，仿真分析得出能量衰减与传输高度呈线性变化。

Laser reaching the process of receiving equipment via the atmospheric transmission, the ability to penetrate the atmosphere is weak, it can be scattered and absorbed by atmospheric molecules, aerosol, dust and others,which results in the attenuation of laser signals and the reducing of detecting ability, the laser energy that reaches the receiving device is reduced, affect the performance of laser communication, therefore, the study of laser transmission characteristics in complex atmospheric environment has important significance. This paper mainly studies the scattering of laser signals and attenuation characteristics in rainfall and fog environment. 　　　In this paper, the physical properties of rainfall and fog is introduced a more detailed elaboration, micron wavelength laser propagation in the atmosphere, the main theory is Mie scattering theory, simulates and analyzes attenuation factor efficiency’s variation features with the change of scattering particle size, at the same time, analyzes of the spatial distribution particle scattering light intensity. Based on rain and fog characteristics and the Mie scattering theory:1) is deduced the theoretical calculation of the attenuation of raindrop size distribution mode in rainfall environment,combining empirical model, by Matlab simulates and analyzes rain attenuation coefficient of M-P, Joss and two empirical model with the change of rainfall rate, it is concluded that the laser transmission attenuation is more serious in light rain than the heavy rain; 2) based on a single property of the droplets, gives common experience model of causing laser attenuation in fog environment,by Matlab simulates and analyzes attenuation characteristics between different models of the advection fog and radiation fog, it is concluded that the the laser wavelength is longer, the attenuation coefficient is smaller, when visibility is more than 500 metres, each model attenuation were similar, but the visibility is less than 500 meters, the difference between them with the decrease of visibility is more and more big, multiple scattering is considered. This paper also discussed laser attenuation when the laser transmission in the fog by oblique cheng,by the simulation analysis it is concluded that the energy attenuation and transport highly linear change.