Adaptive focusing of a high-intensity beam in an irregular medium

Conclusions These model studies show that the performance in adaptive focusing for high-intensity beams in randomly inhomogeneous media is restricted primarily by nonlinear phenomena. The power density at the object is increased by adaptive control and is only slightly dependent on the fluctuation variance for the modes considered and for the range of nonlinearity parameters.In thermal self-action, large-scale spatial distortions predominate, for which one can use adaptive suppression systems with small numbers of control coordinates. In the case of nonlinear refraction in a moving medium, a considerable improvement is obtained by control on the lower aberrations, i.e., by means of the wavefront tilt and curvatures.A current problem in optimizing adaptive-optics systems is evidently the determination of a sufficient set of control coordinates for focusing a high-intensity beam propagating under real conditions.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 11, pp. 30–41, November, 1985.