Pavel V. Korolenko

Influence of mirror edge effects on the beam quality of high power fast flow lasers

Results of theoretical and experimental research of the edge reflection effects in the technologic CW C02-laser with flowing active medium are discussed. It is shown, that diminishing reflections at edges of the out coupling mirror essentially improves the quality of the output beam.

Nonlinear aperture losses in the cavity of an industrial CO2 laser with transverse pumping of the gas

We study the nonlinear behavior of the refractive index of the active medium of an industrial transverse-flow CO2 laser. We consider the role of the light-induced heat release and dispersion of the medium in the formation of an optical wedge, which causes a displacement of the axis of a stable cavity relative to the selecting aperture. We show that, by a proper choice of the size and shape of the aperture, it is possible to reduce the losses that arise on the aperture under the influence of the wedge to a level not reducing appreciably the power of single-mode lasing.

Self-pulsing fast flow laser with controllable depth of power modulation

Numerical simulations of self-pulsing oscillations in fast-flow laser fitted with unstable generator and multipass amplifier were performed. Possibility of the control of the depth of power modulation was shown. A number of governing parameters can be used to vary the regime of lasing in the system. Modulation of output power depending on the pumping rate was observed experimentally in fast-flow CO2 laser.

About nonlinear aperture losses in power single-mode technological CO2 lasers with cross pumping of gas

Results of experimental and theoretical researches of physical nature and characteristics of a nonlinear optical wedge in the active zone of the technological CO2 laser with a cross gas flow are stated. Basic causes of occurrence of a wedge are light-induced give off heat and a dispersion of medium. The optical wedge results in strengthening diffraction losses on select and limiting apertures inside the stable cavity. However the estimations show, that at a correct choice of the aperture sizes and shapes the cavity losses are small and do not reduce appreciably power of the laser.

Industrial CO2-laser with the phase compensation of the high-order cavity mode

Theoretical propositions of powerful technological CO2-laser operation with selection and correction phase of high order cross modes have been experimentally studied. The effective transformation of the high order mode oscillations field into the narrow directed beam with cophased light oscillations at the level of output power up to 1kW with help of phase corrector is reported for the first time. The physical nature intracavity aberrations with negatively influence on the beam quality is analyzed. It is shown that the most significant aberration such as optical wedge arising when we use the cross pumping of active medium and the cross discharge. The prospect of use of the considered method to receive narrow directed radiation is considered at high power values.

Improvement of industrial laser beam quality using phase correction of high modes

Theoretical propositions of powerful technological CO2 laser operation with selection and correction of phase of high order cross models have been experimentally studied. The effective transformation with the help of phase corrector of the high order mode oscillations field to the narrow directed beam at the level of output power up to 1kW is reported for the first time. The physical nature of intra-cavity aberrations with negative influence on the beam quality is analyzed. It is shown that the most significant aberrations such as optical wedge arise when we use the cross pumping of active medium and the cross discharge. The prospect of the considered method application to obtain narrow directed radiation is considered at higher power values.

About particularities of intensities distribution in a cross-section of powerful laser beams

The physical nature and manifestation of several types of instabilities and fluctuation processes in the cavity of the fast-flow CO2-laser are considered. It was established by experiment that optimal design of optical and gas-dynamic laser sections depresses totally the high frequency fluctuations and reduces low-frequency fluctuations to the level 6 - 10%. It was shown that inhomogeneities in the laser cavity are apt to complicate appreciably the space- temporary structure of output laser radiation. To interpret the experimental results influence of phase aberrations on the process of formation of caustics and wavefront dislocations in laser beam is considered.

Laser interferometer with a multibeam cavity

The design and the principle of action of a laser multibeam interferometer are presented. The device is intended for the registration of the small spatial changes of refractivity. Compared to known prototypes, it has higher stability to the influence of different vibrations and high jamproofing. Under ordinary laboratory conditions, it allows measurement of the values of the refractivity changes of about 10-10.

Optical diagnostics of the turbulent flow of the nonequilibrium gas mixture in FAF CO2 laser

The dual-beam method was used to estimate the fluctuations of phase incursion of the probe laser beam in the turbulent flow of the active medium of the fast-axial-flow cw CO2 laser. The dependence of degree of cross correlation of phase incursion fluctuations emerging in the ionized gas on energy input into the discharge has been estimated.

Optimization of an optical system of lidar devices near the ground under conditions of turbulence intermittence

Physical factors affecting the signal to nose ratio in the optical location systems are considered under the conditions of turbulence intermittence. The experimental data on the effects of random wandering, turbulent broadening, changes of the coherence radius of the local intensity fluctuations are obtained for the narrow laser beams. Theoretical model accounting for the result of experiments by change of the ratio between the beam radius nd inner scale of the turbulence has been constructed. It enables to carry out optimization of the optical location paths.