Evidence of Decreased Heterodyne-Detection Efficiency Caused by Fast Beam Scanning in Wind Sensing Coherent Doppler Lidar, and Demonstration on Recovery of the Efficiency With Lag-Angle Compensation

The experimental evidence of the decreased heterodyne-detection efficiency caused by the lag angle is shown using a long-range wind sensing coherent Doppler lidar (CDL) with fast beam scanning. The recovery of the efficiency with the lag-angle compensation is also demonstrated. The receiving beam alignment method synchronized with the beam scanner is used. The measurable range of 12 km with the fast beam scanning of 20°/s in the case of 8-Hz line-of-sight (LOS) update rate was demonstrated with the compensation. This demonstration shows the potential for the wind sensing CDL to satisfy all requirements of long-range, real-time, and fast beam scanning measurement.