Adaptive focusing of radiation on a diffusely scattering reflector under nonlinear refraction conditions

Laboratory experiments were carried out on the compensation of nonlinear distortions of an optical beam by a 15-channel adaptive optical system controlled by a microcomputer. Nonlinear distortions were created by a liquid-crystal light modulator and they resulted in a tenfold reduction of the fraction of energy in the focal spot. Adaptation made it possible to restore practically completely the initial energy parameters of the beam (reducing the integrated width of the spot by a factor of about 3). The adaptive system compensated successfully nonlinear wavefront distortions of ~3 µ amplitude.