Fluctuations of a focused beam wave for atmospheric turbulence probing

This paper demonstrates that a focused beam wave may be effectively used to probe the atmospheric turbulence. Unlike plane and spherical waves, the focused beam has two parameters, i.e., the beam size and the radius of curvature of phase front at the aperture which may be easily varied experimentally. General formulations for the amplitude and phase correlation functions and structure functions of a focused beam wave are given including the effects of wind velocity and time delay. The effects of the beam size and the focal length on the spectral and spatial filter functions and temporal frequency spectrum are examined in detail including the effects of separation, wind velocity, and time delay. Using these functions, procedures are shown to probe the form of the spectral density of the index of refraction, the structure constant, and the wind velocity along the path.