PROPAGATION OF A GAUSSIAN-BEAM WAVE THROUGH A RANDOM-PHASE SCREEN

Tractable analytic expressions are developed for a variety of basic st atistical quantities involving a Gaussian-beam wave propagating throug h a random medium confined to a portion of the propagation path betwee n input and output planes, the limiting case of which defines a thin r andom phase screen. For a plane wave incident on a phase screen locate d midway between input and output planes, it is well known that the st atistics in the receiver plane are in close agreement with those assoc iated with a plane wave propagating through an extended random medium between input and output planes. For a similar comparison between a ph ase screen and extended turbulence in the case of a Gaussian-beam wave at the input plane, the present analysis reveals that the phase scree n must be positioned between input and output planes differently from the plane-wave case, the position being dependent upon the Fresnel rat io of the Gaussian beam. The analytic results developed in this paper for the thin phase screen model are based on the Kolmogorov power-law spectrum for refractive-index fluctuations and the Rytov approximation . Extension of these results to multiple phase screens is also discuss ed.