激光系统的发射光和跟踪光波长通常会有所不同, 在近地面开展发射光轴和跟踪光轴的高精度定标时, 需要考虑水平传输路径上的大气蒙气色差。理论分析得到水平大气蒙气色差与大气温度垂直梯度、气压垂直梯度、激光波长及传输距离之间的关系, 进而分析了近地面水平大气蒙气色差带来的光轴定标误差。利用自动气象站测量了不同高度的大气温度和气压, 计算分析表明近地面 1 km 水平大 气对 1 μm 和 5 μm 两个波段可能会造成 3 μrad 的蒙气色差, 引起 约 1.5 μrad 的定标误差。研究表明为减小光轴定标误差, 需监测近地面水平大气蒙气色差, 并选择在大气蒙气色差较小的时刻进行光轴定标。

In general, the wavelength of the projected laser in a laser system is a bit different from the beacon wavelength used for target acquisition and tracking. So the dispersion influence of atmospheric refraction in the horizontal transmission path should be considered to reduce calibration errors of the optical axis. Firstly, the relationship between dispersion effect of horizontal atmospheric refraction and various practical parameters, such as vertical temperature gradient, vertical pressure gradient, laser wavelength and laser transmitting distance, is deduced by theoretical analysis. Then the calibration errors of optical axis caused by dispersion effect of horizontal atmospheric refraction in the near surface layer is also analyzed. Furthermore, atmospheric temperature and pressure of varying height are measured by means of two automatic meteorological stations. And the calculation results show that the dispersion effect of horizontal atmospheric refraction in the near surface layer for 1 km transmission could be about 3 μrad for 1 μm and 5 μm wavelengths, which would lead to calibration errors of about 1.5 μrad. It indicates that dispersion effect of horizontal atmospheric refraction in the near surface layer should be monitored in order to reduce theoptical axis calibration error, and the optical axis calibration should be carried out when dispersion effect is slight enough.