瑞利多普勒测风激光雷达的频率标定方法

频率标定是瑞利测风激光雷达的关键技术。瑞利测风激光雷达中，通过改变压电陶瓷管的电压实现连续调谐F-P标准具腔长，使出射激光频率处于双边缘透过率曲线的交点处。在连续调谐时，由于压电陶瓷管的磁滞效应引起腔长调谐非线性，从而导致系统误差。分析了该误差的原因及特性，提出了静态软件补偿和动态调频跟踪相结合的频率标定方法。若激光出射频率相对F-P标准具漂移小于100 MHz时，在数据反演时补偿该频率偏差；若相对频率漂移大于100 MHz时，将F-P标准具先退回预设腔长以下，通过逐步增加电压的方式，重新实现频率锁定，保证锁定过程处在磁滞回线的电压上升段，避免了磁滞效应引起的误差。多普勒激光雷达与无线电探空仪的两组对比实验中，在15～30 km高度，风速最大偏差6.22 m/s，平均偏差1.12 m/s。

Frequency calibration for Rayleigh Doppler wind lidar

Precise frequency calibration is critical to maintain the accuracy of wind retrieval from a Rayleigh Doppler wind lidar. The frequency of the laser is locked at the cross-point of the transmission functions of double-edge channels by tuning the cavity length of the Fabry-Perot interferometer (FPI) continuously. However, the non-linearity due to hysteresis in the PZT will introduce systematic errors. To overcome this drawback, a new method of frequency calibration and frequency locking is proposed and demonstrated. If the relative frequency drift between the laser and the FPI is less than 100 MHz, the frequency deviation is monitored and then compensated in the data processing. Once the relative frequency drift is large than 100 MHz, the frequency locking point is reset. In their procedure, the cavity length is shrunk in two steps: first tune the voltage under the preset point, then increase the voltage along the rising edge of the hysteresis loop gradually until the frequency locking is achieved again. In the comparison experiments, the new method is adopted. The maximum (average) wind speed deviation between the results from Doppler lidar and radiosonde is 6.22 m/s (1.12 m/s) in the altitude from 15 km to 30 km.