2-mu m Doppler lidar transmitter with high frequency stability and low chirp

A coherent Doppler lidar system was frequency stabilized in a master-slave configuration by a phase-modulation technique. The short-term frequency sta bility, similar to 0.2 MHz rms, was maintained in a vibrational environment on a ship during a field campaign in the tropical Pacific Ocean. The long- term frequency stability was <2.6 kHz/h. Thus, in many applications, shot-t o-shot frequency correction can be disregarded, which will result in increa sed speed and simplicity of the data-acquisition system. A frequency chirp could not be detected. These properties permit Doppler wind measurements wi th high efficiency and duty cycles to be made, even on airborne and spacebo rne platforms. (C) 2000 Optical Society of America OCIS codes: 280.3640, 14 0.3570.