米散射激光雷达重叠因子及全程回波信号标定技术研究

Investigation on the correction of the Mie scattering lidar’s overlapping factor and echo signals over the total detection range

由于激光雷达光轴夹角的存在和光束质量分布的非均匀性,导致理论回波信号与实际回波信号有较大差别,需要对其进行校正.基于数学推导和软件仿真,给出了激光雷达重叠因子的数学表达式,分析了光轴夹角导致的系统重叠因子在全程探测空间的变化情况;分析了光束分布为高斯分布和均匀分布时的重叠因子变化情况;对激光雷达的距离校正信号和Klett算法公式进行了重叠因子修正,最后在对激光雷达系统参数标定的基础上,在重叠区域利用修正的Klett公式对其所测得到的回波信号进行了修正,在探测盲区利用斜率法修正距离校正信号,进而得到了符合理论与实际情况的激光雷达在全程上校正的消光系数曲线.

There has been great difference between the theoretical signals of the lidar’s echo and its actual signals, due to the angles between the laser beam and its receiving optical axis, and the laser intensity distribution being asymmetrical. So the correction of the echo signal is necessary. According to the mathematical derivation and the software simulation, the mathematical expression of the lidar’s overlap factor is given, and the overlap factor curves with detection range are drawn which express the characters over the total detection range, then the best angle between lidar’s emitting axis and the receiving axis is obtained. The overlap factors are analyzed when the laser is Gaussian with a uniform intensity distribution. The lidar distance correction signal and Klett formula are corrected by the overlap factor, and the instrument parameters of the lidor are measured. In the range where the overlap factor is not zero, its correction echo signals and extinction coefficients can be obtained by using the corrected Klett formula. While in the range of the lidar’s blind zone, the signals can be derived by a slope method. Finally, the total correction curve of the extinction coefficients is gained, and it is in accordance with the actual one correction cuive.