基于法布里-珀罗干涉仪的多普勒测风激光雷达可以实现从对流层到中层大气的高时空分辨率风场探测。然而,实际风场观测时,反演出的径向风速总会存在一个偏差,需要外部的参考风场来消除。从理论出发,分析了出现偏差的原因,得出主要影响因素是法布里-珀罗干涉仪和种子激光器的环境温度。随后对该温度的影响进行了实验研究。通过分别对种子激光器和法布里-珀罗干涉仪环境温度的精确控制,测量激光通过已标定的法布里-珀罗干涉仪的透过率来监测相对频率的漂移与温度之间的关系。实验结果表明,环境温度会影响频率漂移,理论上,对于355 nm测风激光雷达系统,控制1 m/s的径向风速漂移,种子激光器环境温度引起的频率漂移系数为1650 MHz/K,温度控制的精度须小于0.004 K;法布里-珀罗干涉仪环境的温度引起的频率漂移系数为799 MHz/K,温度控制的精度须小于0.007 K。
Direct detection Doppler wind lidar based on Fabry-Perot interferometer has been demonstrated for its capability of atmospheric wind detection ranging from troposphere to mesosphere with high temporal and spatial resolution. However, bias would emerge while retrieving the radial velocity during the observation and an external wind reference is needed to eliminate this bias. Reasons for this bias are theoretically analyzed and results show that the ambient temperatures of Fabry-Perot interferometer(FPI) and seeder laser are main effects. Then this effect of temperature is learned by experiment. By precise control of the ambient temperature of FPI and seeder laser separately, laser transmission through calibrated FPI, which depends upon the temperature, is studied. Using the instrumental function of the FPI, the frequency bias dependence on temperature is obtained. The experimental results show that the temperature coefficient of frequency bias for seeder laser is 1650 MHz/K while the one for FPI is 799 MHz/K, which means the precision of ambient temperature should be theoretically better than 0.004 K for seeder laser and 0.007 K for FPI in 355 nm Doppler wind lidar system.