长波长红外光大气信道传输

采用光子追踪法，模拟光子在大气信道中的随机迁移路径及散射后随机迁移方向。引入光束发散角和接收视场角等参数，建立了包含散射作用的长波长红外大气信道传输模型。运用蒙特卡洛方法进行仿真，分析了雾环境下长波长红外光的大气传输特性。与朗伯-比尔定律进行对比，发现在能见度较低、通信距离较近时接收机接收的散射能量不能被忽略。分析了通信距离、能见度、光束发散角、接收视场角对链路损耗的影响，分析了不同阶次散射对接收机接收能量的影响。发现在给定参数条件下，四阶及以上高阶次散射对接收机接收能量几乎可以忽略。

Long wave infrared transmission in atmospheric channel

A free space optical communication channel model including stochastic transfer distance and direction of photon after being scattered was developed using a Monte Carlo simulation method based on photon tracing. In this model, beam divergence and field of view(FOV) were introduced, the influence of scattering was also in consideration. Simulations using Monte Carlo method and Lambert-Beer Law were carried out under fog condition with long wave infrared. Compared with Lambert-Beer Law, the result shows that the received energy of scattering can't be ignored under the condition of short range and low visibility. The influence of different ranges, visibilities, beam divergences and field of views on pass loss were analysed respectively using Monte Carlo method. The contributions of different scattering orders to total received energy were also illustrated. The effects caused by the 4th or higher orders scattering can be overlooked under given conditions so as to improve the efficiency of calculation.