Adaptive Optics and Optical Vortices

Abstract

The achievement of minimal angular divergence of a laser beam is oneof the most importantproblems in laser physics since many laser applications demand extremeconcentrationof radiation. Under the beam formation in the laser oscillator oramplifier with optically inhomogeneousgain medium and optical elements, the divergence usually exceeds thediffractionlimit, and the phase surface of the laser beam differs from the planesurface.However, even if one succeeds in realizing the close-to-plane radiationwavefront at the laseroutput, the laser radiation experiences increasing phase disturbancesunder the propagationof the beam in an environment with optical inhomogeneities (atmosphere).Thesedisturbances appear with the wavefront receiving smooth, regular distortions,the transverseintensity distribution becomes inhomogeneous, and the beam broadensout.