单频脉冲激光器的频率稳定性显著地影响直接探测多普勒激光雷达的风速测量准确性，工作在半导体抽运Nd:YAG激光器倍频532 nm的种子注入脉冲激光器的典型自由频率漂移可达15 MHz/min，相当于4 m/s风速误差。基于碘分子吸收光谱稳频原理，采用Labview虚拟仪器控制技术，对种子注入脉冲放大式的半导体抽运Nd:YAG激光器进行稳频，实现了脉冲激光器的频率扫描、碘分子1109光谱吸收线的自动匹配和频率锁定。长时间(大于2 h)频率漂移标准偏差为0.8 MHz，等效风速误差为0.2 m/s，达到直接探测多普勒测风激光雷达长时间测量对脉冲激光器的频率稳定要求。

Frequency stability of Q-switched Nd:YAG laser significantly affects the wind measurement accuracy of direct detection Doppler Lidar. The typical free frequency drift of diode-pumped Nd:YAG laser working at doubling frequency 532 nm based on seed injection can reach 15 MHz/min, correspondingly to a weed speed measurement error of 4 m/s. By using virtual instrument control technology of Labview, the frequency of pulsed laser is successfully scanned, and iodine absorption line 1109 is matched automatically, which get the frequency on one of the two slopes of the line. Standard deviation of frequency stability is about 0.8 MHz for a long time (more than 2 h), while the equivalent wind speed error is 0.2 m/s. The requirement of frequency stability is achieved during long-term lidar measurements.