Beam spreading of vortex beams propagating in turbulent atmosphere.

We present some results obtained by numerical modeling of the propagation of vortex beams LG(0l) through a randomly inhomogeneous medium. The vortex beams are the lower order Laguerre-Gaussian modes. Such beams, if propagated under conditions of weak turbulence, also experience distortions, like a Gaussian beam.

Limitations of adaptive control efficiency due to singular points in the wavefront of a laser beam.

Optical vortices occur at light propagation in an inhomogeneous medium, disturbing the operation of adaptive optical systems and assuring a priori continuity of the phase fluctuation function. It is clear that the physical process of the light wave propagation has a threshold of complexity relative to the description and measurement of this process, after which the light wave contains points with zero intensity and there is no continuous wavefront. The appearance of zeros indicates the transition of phenomenon in a new condition.

Influence of the source spectrum on the optical measurements of turbulence.

It is considered how the source spectrum influences the measurement accuracy of optical wave arrival angles, as well as the estimation of the path-averaged structure parameter of the refractive index fluctuations. Two reasons that can cause the wavelength dependence of the variance of fluctuations of wave arrival angles are analyzed. The first one is connected with the fact that phases depend on a wavelength in the approximation of smooth perturbations.

Phase-correction of turbulent distortions of an optical wave propagating under conditions of strong intensity fluctuations.

Phase correction of a plane wave and a spatiolimited beam propagating through a turbulent layer of atmosphere were considered. The required adaptive corrector element size and the system bandwidth were found by numerical simulation. These requirements were determined to be the same as for a weak-intensity scintillation approximation.