Compensation Of Phase Distortions Research Articles

Compensation for phase distortions by three-frequency parametric interaction

An analysis is made of the compensation for phase distortions by wavefront reversal using a parametric frequency converter or a linear spatial filter. Estimates are made of the required accuracy for the transfer of the optimal focusing plane, and of the permissible nonmonochromaticity and divergence of the pump radiation in regular and random models of an inhomogeneous medium. It is shown that the limiting transverse inhomogeneity scale is governed by the width of the converter spread function and the maximum phase lead may be of the order of 2π. The results of the calculations were verified experimentally for generation of difference-frequency radiation in a quadratically nonlinear medium.

Efficiency of the compensation of phase distortions of optical waves

A theoretical analysis is made of the efficiency of a system for the compensation of phase fluctuations of an optical wave traveling in a turbulent atmosphere. In this system the distortions are compensated on the basis of measurements of phase fluctuations in the reflected wave. A correlation function for the uncompensated error and the compensation parameter a are introduced. Calculations carried out in the approximation of smooth perturbations indicate that the compensation on the basis of reflected waves is effective only up to distances at which the Fresnel zone does not exceed the external scale of turbulence.

Holographic compensation of phase distortions in the radiation fields of solid-state lasers

The angular divergence of the radiation of ruby and neodymium lasers was reduced by a holographic method. A technique for the fabrication of a corrector of phase distortions in the radiation field of a laser was developed and tested.

Compensation for Atmospheric Phase Effects at 106 μ

A holographic technique to compensate for atmospherically induced phase distortion of a 10.6-micro laser beam is presented. After a brief outline of the principle of adaptive phase-distortion compensation, the experimental setup to demonstrate feasibility is described. Results obtained for a reflecting target at distances of 150 m and 4600 m are presented and discussed in detail. It is shown that the power delivered onto a target and thus the return signal can be significantly increased by the principle of adaptive phase-distortion compensation. By compensating for phase distortions in both the transmitted and received beams, the signal-to-noise ratio of the received signal can be improved by a factor of N(2), N being the number of apertures used, if the phase relation was completely random beforehand. The results of these tests demonstrate that large arrays can be utilized in spite of the distorting effects which are normally produced by the atmosphere.