Beacon creation and characterization for beam control in strong turbulence

There is strong interest in developing adaptive optics solutions for extreme conditions, such as laser beam projection over long, horizontal paths. In most realistic operational scenarios there is no suitable beacon readily available for tracking and wave front sensing. In these situations it is necessary to create a beacon artificially. In this paper we explore two strategies for creating a beacon: (1) scattering an intially focused beam from a surface in the scene; and (2) use of a Rayleigh beacon in the atmosphere between the transmitter and the target to accomplish compensation for part of the path. In many cases of practical interest, beacons created by scattering of the light from a surface in the scene results in beacons which are anisoplanatic, and hence provide poor beam compensation results. Partial path compensation based on a Rayleigh beacon provides comparable performance in some cases