Range Dependent Turbulence Characterization by Co-operating Coherent Doppler Lidar with Direct Detection Lidar

摘要

The backscattered signal power of a coherent Doppler Lidar (CDL) system that is used for wind sensing was validated against a direct detection Lidar system. In coherent detection, the received signal power depends on the overlap function of the backscattered and local oscillator fields. This overlap function is dependent on the loss of coherence of the backscattered field, which is influenced by refractive index variations of the atmosphere due to turbulence. A direct comparison of the backscattered signal power of the CDL with that of the direct detection Lidar requires that the effect of coherence loss and the overlap function as function of range is accounted for. In this study, we report on the CDL wind measurements and we present the analysis of the range dependent refractive index variations of the CDL by appropriately fitting the backscattered signal power with direct detection signal power measurements.