Turbulence effects on target illumination by laser sources: phenomenological analysis and experimental results.

A phenomenological and analytical description is given of atmospheric turbulence effects oh laser beam waves, including the improved target irradiance characteristics resulting from cancellation of turbulenceinduced beam wander through reciprocity tracking. The mechanisms related to the mean irradiance include diffraction, wander, and wavefront distortion (beamspread), while irradiance-fading is caused by wander, first-order scintillation, and coherent fading. The phenomenological description unifies the often fragmentary and inconsistent treatment of beam wave phenomena found in the literature and is sufficiently accurate for engineering purposes. It will be shown that wander-cancellation and control of the transmitter beam diameter can result in substantial improvements in target illumination. The analyses are compared with experimental data for the detailed statistical and spectral characteristics of on-axis target irradiance.