A.V. Kudryashov

Wavefront compensation method using a Shack-Hartmann sensor as an adaptive optical element system

This paper considers the use of an adaptive optical system for compensating aberrations of a laser radiation wavefront. Bimorph mirrors are used as correctors, and the wavefront is measured by a Shack-Hartmann sensor. Disadvantages of this adaptive system and ways to overcome them are discussed.

An adaptive optical system for controlling laser radiation

This paper presents an adaptive optical system intended for focusing the radiation of powerful processing lasers. The system consists of a wave-front corrector, a wave-front meter, and a software-hardware system for controlling the corrector. A flexible bimorph mirror is used as a corrector. An M2 sensor is used to analyze the radiation-focusing quality, making it possible to estimate such parameters of the laser radiation as the diameter, the divergence angle, and the quality parameter M2. The bimorph mirror is controlled by means of a combined method, based on gradient methods of searching for the extremum and a genetic algorithm. The system makes it possible to correct low-order aberrations and to estimate the focusing efficiency of the laser radiation.

Isoplanatism of the optical system of the human eye

The size of the isoplanatism zone is determined on the basis of experimental measurements of aberrations of the eye for various positions of the test point on the retina of the eye. For the patients examined here, the angular size of the zone varied from 1.5° to 2.5°.

Laser beam formation by adaptive optics

This paper discusses the novel adaptive optical closed loop system with water-cooled bimorph mirror as a wavefront corrector to compensate for the aberrations of high-power CW laser beam. Shack-Hartmann wavefront sensor is used as an element for feedback control. Comparison of phase conjugation and modified hill-climbing technique is shown.

Screw Phase Dislocation Formation by Means of Flexible Bimorph Mirror

Formation of the given laser beam intensity and phase is important to solve practical and scientific problems. Bimorph flexible mirror is one of the most widely used devices for this purpose. In the work we present results of numerical and experimental formation of the vortex beam by means of the bimorph flexible mirror. To determine the required electrode grid we have developed a unique algorithm that allows finding the best suited semipassive bimorph mirror electrode spacing for reproducing almost all arbitrary specified phase profiles

Creating a model of the human eye by the methods of adaptive optics

This paper proposes a simulator of the aberrations of the human eye that is capable of reproducing monochromatic aberrations of the human eye and their temporal dynamics.

Hill-climbing algorithm for adaptive optical system with Shack-Hartmann sensor

We describe multi-dither adaptive optical system based on Shack-Hartmann wavefront sensor. RMS of the wavefront is minimized to get the best correction of the aberrated laser beam. Hill-climbing algorithm is used to determine voltages to be applied to the electrodes of a bimorph mirror which is used as a wavefront corrector.

Analysis of accuracy of shack-hartmann wavefront sensor measurements

Shack-Hartman wavefront sensor for scientific investigations of wave fronts is represented in paper. It was shown that this type of wavefront sensor has multifunctional possibilities to measure laser radiation. Aspects of accuracy measurements increasing and dynamic range expansion are discussed.Samples of schemas and results of wavefront measurements to high power solid state lasers are presented.

Bimorph flexible mirror for vortex beam formation

We present a novel algorithm of bimorph mirror grid determination. Its usability is demonstrated on practical examples of defining electrode grid to form a vortex beam. We briefly describe the developed finite element bimorph mirror model, designed to evaluate an arbitrary electrode response function.

Femtosecond laser beam improvement: correction of parabolic mirror aberrations by means of adaptive optics

This paper describes the use of closed-loop adaptive optical system to improve the focusing of femtosecond laser beam. Our adaptive system corrects for the low-order aberrations of laser. But even if the aberrations of the laser beam are compensated the focal spot obtained with parabolic mirror is still far from ideal one. And the reason is the aberrations of the parabolic mirror and its poor adjustment. Comparison of phase-conjugate and multi-dither algorithms to correct for the parabolic mirror aberrations is presented. The principle of proper adjustment of the parabolic mirror based on M2 minimization is shown.