多次散射是影响激光雷达探测水体光学特征参数(包括吸收系数a,衰减系数c,漫射衰减系数Kd)的重要因素,而视场(field of view, FOV) 是造成接收回波中多次散射比重差异的关键参数。基于Mclean-Walker海洋激光雷达模型,引入接收视场参数θrcvr,分别针对船载、 机载和星载平台激光雷达进行探测回波计算,假设探测高度依次为10, 300, 7×105 m,在接收视场变化情况下分析多次散射因子对反演 水体光学特征参数的影响。结果表明,利用水体中激光散射回波反演水体光学特征参数的方法中,假定激光准直入射, θrcvr与探测高度H 是影响反演结果的直接因素,激光雷达衰减系数Klidar的物理意义随之变化,当θrcvr近似为0时Klidar 反演值为衰减系数c,随θrcvr×H增大, Klidar反演值逐渐接近于Kd。

Multiple scattering is an important factor for measuring water optical characteristic parameters (including absorption coefficient a, attenuation coefficient c, diffuse attenuation coefficient Kd) by lidar. Meanwhile, field of view (FOV) is a key parameter which affects the proportion of multiple scattering in receiving echoes. A parameter of FOV (θrcvr) is introduced into the inversion method of water optical properties by ocean lidar based on the Mclean-Walker model. In the cases of shipboard, airborne and spaceborne platforms at the height of 10, 300, 7×105 m respectively, scattering echoes are calculated according to the lidar theory. The inversion of water optical parameters is analyzed with multiple scattering factor under different FOVs. It is shown that assuming the incident laser of highly collimated, θrcvr and detecting height H are critical factors which influence inversion results in the method for obtaining water optical parameters from laser scattering echo. It is worth noting that the physical meaning of the lidar attenuation coefficient Klidar changes with the factors. Klidar can be considered as c when θrcvr is approximately 0. And Klidar gradually approaches Kd with the increase of θrcvr×H.