基于脉冲激光器的水下距离选通成像雷达是水下光电探测的重要手段之一，为了在探测距离内获得有效的照明范围，在小角度散射条件下，推导了水体光束扩展函数，提出了一种水下高斯光束激光照明模型。采用532 nm调Q 倍频Nd:YAG 脉冲激光器实验测量了不同发散角激光在水下目标平面上的照度分布半径。与其他模型仿真结果进行对比表明，该激光照明模型能够较好地吻合实验结果。模型误差随着照明距离和激光发散角的增加而变大，在目标平面直径为1 m 的圆形照明区域条件下，仿真得到的照明光斑半径在8.5 个衰减长度范围内与实测值误差不超过0.1 m。

Underwater range-gated imaging is an important method of underwater photoelectric detection. In order to obtain sufficient illuminating areas, an efficient model of the irradiance spatial distribution is derived for Gaussian laser illumination in the water based on small angle scattering theory. Irradiance distribution measurements of a 532 nm laser source with different divergence are presented. The errors of the model become large when the divergence of the laser increases and the illuminating range extends, but the resulting predictions of the analytical model are in good agreement with the experimental measurement over wide range of illuminating distance by limiting the field of illumination to the circle region with a diameter of 1 m. These predictions can give enough precision for underwater range-gated imaging systems.