单次大气散射效应对星载激光测高仪接收脉冲回波的影响

Influence of single atmospheric scattering effect on received pulse waveform of satellite laser altimeter

大气散射效应是影响星载激光测高仪接收脉冲回波的重要因素。根据星载激光测高仪接收脉冲回波信号与大气响应函数之间的关系式,在忽略大气多次散射效应的条件下,通过分析散射激光束的几何轨迹和散射概率,推导出单次大气散射激光脉冲和接收脉冲回波的特征参数的数学解析式。以地球科学激光测高仪系统参数为输入,采用数值仿真分析的方法,模拟了大气散射介质分布、激光指向角和目标倾斜角对接收脉冲回波信号特征参数的影响。结果表明,若散射介质的高度和粒子半径范围分别为0.2~6 km和0~120μm,则其对接收脉冲回波的能量、重心和均方根脉宽的影响最大值分别超过15%、250 cm和800 cm。随着激光指向角或目标倾斜角的增加,接收脉冲回波的能量基本不产生影响,但是其重心和均方根脉宽近似呈线性增加趋势。同时,采用高斯拟合方法可以减小大气散射效应对接收脉冲回波的影响。所得结论对于接收脉冲回波的数据处理与分析以及激光测距精度的评估具有一定的指导意义。

The atmospheric scattering effect is important influence factor on received pulse waveform of satellite laser altimeter. According to the relationship expression between the received pulse signal （RPS） and atmospheric response function, the geometric track and scattering probability of laser beam were analyzed under the condition of ignoring multiple atmospheric scattering effects. Moreover, the analytic models on characteristic parameters of scattering laser pulse and RPS were deduced. In terms of geosicence laser altimeter system（GLAS） parameters, the impact of atmospheric medium distribution, laserpointing angle and slope angle on characteristic parameters of RPS were simulated by using method of numerical simulation. The results show that the maximums of energy, centroid and RMS pulse-width of RPS are separately more than 15%, 250 cm and 800 cm, when the ranges on height and particle radium of scattering medium are 0.2-6km and 0-120 μm. Meanwhile, with the increment of laser pointing angle and target slope angle, the energy of RPS remains basically unchanged, but the centroid and RMS pulse- width present incremental trend. The Gaussian fitting algorithm contributes to reduce the influence of atmospheric scattering effect on RPS. The final conclusion has instructive significance for the processing and analysis of RPS and assessment of laser range precession.