Vadim V. Samarkin

Correction of strong phase and amplitude modulations by two deformable mirrors in a multistaged Ti:sapphire laser

We describe a novel scheme consisting of two deformable bimorph mirrors that can free ultrashort laser pulses from simultaneously present strong wave-front distortions and intensity-profile modulations. This scheme is applied to the Max-Planck-Institut für Quantenoptik 10-TW Advanced Titanium-Sapphire Laser (ATLAS) facility. We demonstrate that with this scheme the focusability of the ATLAS pulses can be improved from 10(18) to 2x10(19) W/cm(2) without any penalty in recompression fidelity.

Control of high power CO2 laser beam by adaptive optical elements

Abstract The spatial and temporal beam characteristics of a cw pumped CO 2 laser with active mirrors in the cavity have been investigated. The five-pass unstable cavity with magnification M = 2 was used, where one of the folding mirrors was replaced by a water cooled flexible mirror based on a bimorph piezoelement. The pulse-periodical regime of the laser generation in different frequency range of controlling signals with a 100% beam power modulation depth was realized. The maximal pulse power value exceeding three times the average power level was obtained at 3.8 kHz pulse repetition frequency. The modulation and stabilization of the output power of a CO 2 100 W laser with a Fabry-Perot interferometer was realized.

Active laser resonator performance: formation of a specified intensity output

We discuss the formation of a specified super-Gaussian intensity distribution of a fundamental mode by means of an intracavity controlled mirror, which is a water-cooled bimorph flexible mirror equipped with four controlling electrodes. Analysis has confirmed the possibility to form fourth-, sixth-, and eighth-order super-Gaussian intensity distributions at the output of the stable resonators of industrial cw CO(2) and YAG:Nd(3+) lasers. We present the results of the experimental formation of fourth-order and sixth-order super-Gaussian fundamental modes at the output of a cw CO(2) laser by means of an intracavity flexible mirror. We observed an increase in power up to 12% and an enlargement of the peak value of the far-field intensity by as much as 1.6 times that with a Gaussian TEM(00) mode of the cw CO(2) laser.

Bimorph mirrors for powerful laser beam correction and formation

Bimorph mirrors for laser beam correction and formation were developed and investigated. Different types of substrates and active piezoceramics materials were considered to fabricate temperature independent shape of the mirror surface and to maximize the sensitivity of the mirror. High reflectivity coatings for different wavelengths were studied.

Adaptive optical system based on bimorph mirror and Shack-Hartmann wavefront sensor

This paper discusses the novel adaptive optical closed loop system with bimorph mirror as a wavefront corrector and Shack-Hartmann wavefront sensor to compensate for the aberrations of the laser beam occurred during the distribution of the beam from laser to processed material. 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 15th Zernike polynomial (excluding tip-tilt).

Adaptive optical elements for laser beam control

Bimorph mirrors for laser beam correction and formation were developed and investigated. Different types of substrates and active piezoceramics materials were considered to fabricate temperature independent shape of the mirror surface and to maximize the sensitivity of the mirror. High reflectivity coatings for different wavelengths were studied.

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.

Low-cost adaptive optical devices for multipurpose applications

Reflecting and refracting modal correctors for compensation of large scale static and dynamic wave front aberrations in the lasers and image formation optical system have been developed and investigated. A grant attention was given to the problem of the thermal stability of the mirror surface. The new transparent type of corrector, namely, the active lens was proposed. The 20 channel compact and low-cost control system capable of interfacing with personal computer was developed.

Largest in the world bimorph deformable mirror for high-power laser beam correction

The deformable mirror with the size of 410x468 mm controlled by the bimorph piezoceramic plates and multilayer piezoceramic stacks was developed. The results of the measurements of the response functions of all the actuators and of the surface shape of the deformable mirror are presented in this paper. The study of the mirror with a Fizeau interferometer and a Shack-Hartmann wavefront sensor has shown that it was possible to improve the flatness of the surface down to a residual roughness of 0.033 μm (RMS). The possibility of correction of the aberrations in high power lasers was numerically demonstrated.

Adaptive Optics for High-Power Laser Beam Control

This paper presents an adaptive optical closed loop system with a bimorph mirror as a wavefront corrector and a Shack-Hartmann wavefront sensor to compensate for the aberrations of high power lasers. An adaptive system can correct for the low-order aberrations in the real-time — the frequency of corrected aberrations is less then 25 (30) Hz. The amplitude of such aberrations — about 7 microns. These parameters are mostly determined by the 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 TW laser systems such as ATLAS, LULI and Beijing Institute of Physics.