Alexey Rukosuev

Extremely high-power CO 2 laser beam correction

This paper presents the results of high-power CO2 laser-aberration correction and jitter stabilization. A bimorph deformable mirror and two tip-tilt piezo correctors were used as executive elements. Two types of wavefront sensors, one Hartmann to measure higher-order aberrations (defocus, astigmatism etc.) based on an uncooled microbolometer long-wave infrared camera and the other a tip-tilt one based on the technology of obliquely sputtered, thin chromium films on Si substrates, were applied to measure wavefront aberrations. We discuss both positive and negative attributes of suggested wavefront sensors. The adaptive system is allowed to reduce aberrations of incoming laser radiation by seven times peak-to-valley and to stabilize the jitter of incoming beams up to 25 μrad at a speed of 100 Hz. The adaptive system frequency range for high-order aberration correction was 50 Hz.

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.

Genetic and hill-climbing algorithms for laser beam correction

We present an adaptive optical closed loop system to obtain a good focused beam. A bimorph mirror is used as a wavefront corrector and CCD camera at the focal plane of the lens is a sensor. Such adaptive system can correct for the low-order wavefront aberrations without any sophisticated wavefront sensors.

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.

Extremely high-power CO2 laser beam correction.

This paper presents the design of the closed loop adaptive system to measure and correct for the aberrations of CO2 laser radiation. We considered two wavefront sensors—one sensor is based on commercially available IR camera while the second one—on the so-called thin film sensors. Also we present the design of two bimorph deformable mirrors to be used under high power laser radiation. We discuss both positive and negative attributes of these devices and the possibility to use them in the real laser high-power systems.

Adaptive optics and high power pulse lasers

Some peculiarities of the use of adaptive optical elements and the whole system to correct for the aberrations of high power single pulse lasers are discussed in this paper. The examples of the use of adaptive system to correct for the aberrations of some lasers are presented. As a corrector we used bimorph multi electrode deformable mirror while as a sensor - Shack- Hartmann wavefront sensor.

High-power lasers and adaptive optics

This paper presents adaptive optical closed loop system with bimorph mirror as a wavefront corrector and Shack-Hartmann wavefront sensor to compensate for the aberrations of the high power lasers. Adaptive system can correct for the low-order aberrations in the real-time -- the frequency of corrected aberrations is less than 25 (30) Hz. The amplitude of such aberrations -- about 7 microns. These parameters are mostly determined by utilized Shack-Hartmann wavefront sensor. Number of corrected aberrations -- up to 30th Zernike polynomial (excluding tip-tilt). We are presenting the results of the use of our adaptive system in several high-power laser systems such as ATLAS, LULI, JAERI and Beijing Institute of Physics.

Multi-dither adaptive optical system for laser beam shaping

We describe an adaptive optical closed loop system with bimorph mirror as a wavefront corrector and CCD camera at the focal plane of the lens as a sensor to obtain a good focal spot. Adaptive system can correct for the low-order aberrations with the frequency of corrected aberrations about 5 Hz. These parameters are mostly determined by the deformable mirror properties and multi-dither algorithm.

Fast adaptive optical system for 1.5 km horizontal beam propagation

Fast adaptive optical system can be used, for example, for correction of laser beam passed through a strong turbulent atmosphere. The frequency that such a system should operate with to achieve an acceptable level of wavefront correction is about 1 - 1.5 kHz. There are two most popular methods to develop this system: by using a standard PC computer and by using FPGA. This paper presents the advantages and disadvantages of each of these approaches. The results obtained with the use of these systems are presented. Recommendation for achieving higher performance are given.