降雨对无线激光通信的影响

通过激光信号在雨介质中传输的实验发现，在大雨环境下，激光信号透射率要比在小雨或微雨的情况下大。这说明光信号在小雨时衰减较大，在大雨时衰减较小。这一现象与人们通常所认为的有所不同。针对降雨对激光信号的影响，根据Mie散射理论和Weibull雨滴尺寸分布模型，分析了不同尺寸的粒子对光的散射作用以及对衰减效率因子的影响，推导出单球粒子对光波的衰减公式，得到了衰减与降雨率的确定关系。通过数值计算发现，与小粒子相比大粒子的前向散射光强更大且更加集中；激光信号在雨介质中传输时，衰减系数在小雨时较大，中雨、大雨时较小，暴雨时不断增大。这一结果与实际情况较吻合，为激光在通信系统中的应用提供了一定的理论依据。

Effect of Rainfall on Wireless Laser Communication

In the experiments of laser signal transport in rain medium, it is obvious that the transmission in heavy rain is bigger than that in light rain. This shows that the attenuation of light signal in light rain is bigger than that in heavy rain. The transmission attenuation of wireless laser communication in rain is noticeable. According to the theory of Mie and Weibull raindrop spectrum, the effects of the particle scales on laser scattering and attenuation efficiency factor are analyzed, and the attenuation formula of the light wave of a single particle is deduced. The definite equations between the attenuation and the rainfall ratio are obtained. The result shows that scattering intensity of particle in heavy rain is bigger than that in light rain in forward direction, and the forward scattering intensity increases. When laser signal transmits through rain, attenuation coefficient in light rain is big, while it is small in moderate rain and heavy rain, and increases in rainstorm. This result coincides with the facts. Attenuation characteristic of laser in rain provides theoretical basis for laser applied in the communication system working in the rain.