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地球表层的大气折射可对激光测高仪的激光脉冲传输造成延迟,该延迟对激光飞行时间的测量精度以及地球表面三维轮廓的监测造成显著影响。因此,激光测高仪测距精度需要通过大气传播误差函数进行修正。着重讨论了激光脉冲基于天顶延迟的计算方法和相关映射函数模型的选择,并采用NMF连分式映射函数分别对干项和湿项进行计算。结果表明,在1.064μm波长,指向角偏差不超过10°的激光测高仪系统中,干项延迟可达2.35 m,为主要误差源,湿项延迟变化从1~4 mm不等,基本可以忽略。
Atmospheric refraction on the earth’s surface can delay laser pulse transmission by the laser altimeters, which have a significant impact on the accuracy of laser-time-of-flight measurements and the monitoring of three-dimensional outlines of the Earth’s surface. Therefore, the accuracy of laser altimetry ranging need to be corrected by the atmospheric propagation error function. The calculation method of laser pulse based on the zenith delay and the selection of the related mapping function model are emphatically discussed, and the dry items and the wet items are calculated respectively by the NMF continuous fractional mapping function. The results show that in the laser altimetry system with 1.064μm wavelength and no deviation of the orientation angle of more than 10 °, the dry-period delay is up to 2.35 m, which is the main error source. The wet-type delay varies from 1 to 4 mm, ignore.