机载海洋激光雷达接收信号的数学模型

Mathematical Model of Recieved Signal for Airborne Oceanological Lidars

机载海洋激光雷达通常被应用于近海岸区域的水下地形测绘、水质和水底特征参数的勘测，新的应用需求对测绘精度与勘测精度的要求越来越高，因此需要更精确的雷达信号解析式，实现水深测量、水质和水底特征参数的反演。基于Mclean等给出的光束扩散函数和海水介质传递函数，采用傅里叶变换方法，引入多次散射和脉冲时间展宽的影响，推导了发射系统和接收系统共轴的水底反射光和水体后向散射光信号的解析表达式，给出了系统衰减系数的计算方法，分析了脉冲展宽对深度测量误差的影响，在浑浊海港海水中，脉冲展宽可达到数十纳米量级。该数学模型能够更准确地描述机载海洋激光雷达接收信号的特征，能够用于分析机载海洋激光雷达的性能，并为海水深度的归算、水体与水底参数的反演提供一定的理论依据。

Airborne oceanological lidars are usually applied in bathymetry of near-shore ocean water and reconstructing the optical characteristics of ocean water medium. New applications request much more accuracy in oceanological topography and ocean water quality reconnaissance, and need more accurate analytic model of lidar return signals for bathymetry and reconstructing the water quality parameters. Fourier transform method is used to construct the analytic model of bottom return signals and water backscattering signals for monostatic lidar based on analytic beam spread function and ocean medium transfer function given by Mclean et al. , and in this analytic model, the multiple scattering and pulse stretching are considered and discussed, and the calculating method of downwelling irradiance attenuation coefficient and lidar attenuation coefficient is given, and the results indicate that the pulse stretching time can reach tens of nanoseconds in turbid harbor water. The analysis can offer some references for depth and water quality parameter reconstruction algorithms in theorizing.