Imaging performance of long-range laser scanning through atmospheric turbulence

The process of laser scanning a target to form an image through atmospheric turbulence is studied in terms of the optical transfer function (OTF). The problem of scanning a two-dimension target within the Fresnel zone distance is examined for long and short time exposures. An OTF for wave front tilt is introduced to describe the specific effect of beam wander. An analysis for typical operational parameters shows that wave front tilt can be a more significant limitation to imaging performance at high spatial frequencies than short exposure effects (e.g., beam spread). Wave optics simulations are performed to visualize the performance of the scanning method through turbulence and compare the results with the theoretical model.