目前国内外研究激光在雨中传输的衰减问题时主要有两种模型: 散射模型和遮挡模型。但是遮挡模型在处理位于激光器视场近端的大尺寸雨滴时存在理论缺陷, 而散射模型对于视场远端的雨滴多次散射问题的计算量过于庞大。提出了一种基于接收端雨滴投影圆面积判据的雨滴衰减模型改进算法, 对接收透镜视角内出现单个雨滴全遮挡的情况进行了修正。并且采用MATLAB对模型进行了仿真分析, 得到改进的衰减模型与散射模型和遮挡模型的衰减曲线对比图。最后, 通过自然雨场实验验证改进理论算法的精确度, 结果表明: 传输距离在100 m且降雨量为1.2 mm/h时, 改进的理论模型相比较原遮挡模型精度提高了54.6%, 说明上述改进算法能够提高雨滴衰减模型的精确性。该项目的研究为蓝绿激光大气通信探测技术的发展提供了一定的理论支撑。

At present, there are two models applied in the study at home and abroad in an attenuation model of rain transmisson, which are scattering model and shading effect model. However, the shading effect model has a theoretical defect in dealing with large-sized raindrops located near the laser field of view, and the scattering model requires an enormous amount of computation caused by the multi-scattering problem at the far end of the field of view. This paper presented an improved algorithm for the raindrop attenuation model which was based on projected area of raindrops at receiver. The algorithm corrected the case when a single raindrop was obscured within the viewing angle of the receiving lens. The model was simulated by MATLAB, and the attenuation correlation curves of the improved attenuation model, the scattering model and the shading effect model were obtained. Finally, the accuracy of the improved algorithm was verified by the natural rain field experiment. The results show that compared with the shading effect model, the accuracy of improved model is improved by 54.6% when the transmission distance is 100 m and the rainfall rate is 1.2 mm/h. It is shown that the improved algorithm can improve the accuracy of the raindrop attenuation model. The research of the project provides a theoretical support for the development of the blue green laser atmospheric communication detection technology.