Bistatic coherent laser radar performance. [Wind remote sensing]

Wind velocity can be obtained using a laser radar system by measuring the Doppler shifted backscatter from aerosols and particulates in the atmosphere. Doppler lidar systems for wind velocity measurements can be classified into two categories: coherent detection and incoherent detection. The ultimate goal for both types is to measure a frequency shift between the transmitted laser pulse and the return laser pulse. This frequency shift is proportional to some component of the wind velocity, depending on the system configuration. How accurately these systems can measure the frequency shift, and thus the velocity, is dependent upon the system's characteristics. Existing Doppler lidar systems employ monostatic configurations which require scanning a volume to obtain wind velocity and direction. Range resolution in these systems is normally obtained by using a pulsed laser system. This places a fundamental limit on the range-velocity resolution product. The purpose of this research is to investigate the feasibility of utilizing a multistatic configuration for measuring 3-dimensional vector winds. In the multistatic configuration, horizontal and vertical resolution are determined by the telescope field-of-view, laser divergence, and baseline separation distance between the laser and the telescope. This enables the use of a continuous-wave or long pulse laser transmitter (narrow spectral width) and eliminates the dependence between range and velocity resolution. The results of this research have shown that a multistatic Doppler lidar system will provide accurate estimates of wind velocity within the tropospheric boundary layer (up to about 5 km) with high spatial resolution.