Density of turbulence-induced phase dislocations.

Under certain conditions, light-wave propagation through turbulent media causes a specific type of phase distortion: so-called phase dislocations. A salient feature of phase dislocations is an appearance of zones where the phase turns out to be a multivalued function of coordinates. The problem of turbulence-induced phase dislocations is considered. Both a theoretical treatment and simulations based on the numerical solution of a parabolic equation are used for estimation of the dislocation density. Various turbulence conditions, ranging from weak to very strong ones, are considered as well as the dependences on wavelength, and the inner scales of turbulence are presented. An empirical formula for the dislocation density suitable for a wide range of turbulent and propagation conditions is derived. The results obtained can be useful for both atmospheric and adaptive optics.