Dual frequency technique for Doppler wind lidar measurements

A variation of the direct detection Doppler Lidar method known as the edge technique is discussed. This new method uses a frequency-agile laser transmitter to alternate the outgoing laser pulse between the two edges of a high resolution Fabry-Perot etalon. The difference in sign of the two slopes of the edge allows the unwanted molecular return signal to be eliminated as a background error source. This technique is similar to that of the "double-edge" technique, with the main advantage being reduced complexity and cost for the system. By minimizing the error in the wind velocity measurement due to the molecular return, transmitter powers, within the eye-safety range, may be utilized to measure winds within the planetary boundary layer (PBL) with reasonable accuracy for many applications.