由于激光光束在降雨中传输时会产生雨滴的后向散射, 引起定距系统的虚警、失效等.以几何光学散射理论为基础, 建立雨滴后向散射模型并计算不同降雨条件下的后向散射系数, 结合工程应用计算不同降雨条件和传输距离下的系统信噪比, 分析雨滴后向散射对系统信噪比的影响.计算结果表明, 传输距离一定时, 系统信噪比将随着降雨率的增大而减小, 暴雨中衰减率高达11%; 在相同降雨条件下, 作用距离从10 m增大至15 m, 信噪比衰减率达到46%以上.降雨大小和作用距离是影响系统信噪比的重要因素, 为脉冲激光定距系统在降雨环境下的目标识别以及高抗干扰性能的优化提供了依据.

The laser beam transmitting in the rain would be scattered and attenuated by the raindrops, so that the laser ranging system will be false alert and invalidation. Based on geometric optics theory, the raindrop backscattering model was founded, and the backscattering coefficients of different rainfall rates were calculated. Combined with engineering application, the signal-to-noise ratio at different rainfall rates and transmission distances were calculated, and the affect of raindrop backscattering to the system SNR is analyzed. The calculation results indicate that the system SNR is decreasing with the increasing of the rainfall rates and the attenuation rate is up to 11% in the heavy rain. And at the same rainfall rate, the attenuation rate of SNR is up to 46% or more when the distance increases from10 m to 15 m. The rainfall rate and distance are the important factors to affect the system signal-to-noise ratio, so the study on backscattering characteristics has important instruction for the design and optimization of high anti-interfering performance laser ranging system.