A two-mode CO<sub>2</sub> laser is used as transmitter in a 10-μm heterodyne Doppler lidar (HDL) to take advantage of a spectral diversity technique, i.e., independent realizations obtained with different spectral components. The objective is to improve the properties (i.e., less variance) of power returns from a hard target. The statistical properties are presented first for a broad-spectrum laser transmitter and then for a two-mode laser transmitter. The experimental results for a cooperative diffuse hard target show that the return signals for a frequency separation Δ<i>f</i> = 15 MHz can be decorrelated, depending on the angle of incidence and the target roughness. The experimental results show that the spectral diversity technique improves the performance of the HDL.
© 2000 Optical Society of America
(010.3640) Atmospheric and oceanic optics : Lidar
(030.6140) Coherence and statistical optics : Speckle
(040.2840) Detectors : Heterodyne
(280.1910) Remote sensing and sensors : DIAL, differential absorption lidar
(290.5880) Scattering : Scattering, rough surfaces
Philippe Drobinski, Pierre H. Flamant, and Philippe Salamitou, "Spectral Diversity Technique for Heterodyne Doppler Lidar that uses Hard Target Returns," Appl. Opt. 39, 376-385 (2000)