针对回波特性进行理论分析和数值模拟,讨论影响机载激光测深系统的最小可探测深度的各种因素和解决的技术途径。采用窄激光脉冲,高速探测器,小接收视场角,可以改善海表和海底反射信号的叠加。分析海表和海底反射脉冲的特征,提出采用双高斯脉冲拟合方法,从叠加的回波信号中分离海表、海底反射信号,降低机载激光测深系统的最小可探测深度,满足海岸带测绘应用。利用实验室模拟装置进行测量实验,利用提出的方法分离表面和底部反射信号,得到0.4 m的最小可探测深度。同时比较了雪崩二极管和光电倍增管的测量结果,两者的测量精度相当。

Based on the theoretical analysis and data simulation of the characteristics of the return signal, the factors influencing the capability of minimum depth of an airborne laser bathymetry and the improved technical methods are discussed. The use of narrow laser pulse, high-speed detector and small field-of-view can decrease the overlap of the surface and the bottom reflected signals. Based on the analysis of the characters of the surface and bottom reflected pulse, a method using double-Gaussian pulses fitting to separate the surface and the bottom reflected signals from the overlapped returns and to improve the capability of minimum depth using an airborne laser bathymetry is proposed to meet the applications of coast measurement. A simulated experiment was conducted and a minimum depth of 0.4 m has been achieved with the proposed method. The measurement results of the avalanche photodiode (APD) and the photomultiplier tube (PMT) are compared, the similar accuracy was obtained.