M. G. Galushkin

New kilowatt waveguide CO 2 process lasers with high radiation quality

This paper presents a type-series of kilowatt waveguide CO2 process lasers with high radiation quality. The technical advantages and prospects of using such systems for laser processing are discussed.

The development of turbulence in the active medium of a fast-flow gas-discharge laser

The effect of pump nonequilibrium on the heat generation and the parameters of turbulent flow in the active medium of a fast-flow gas-discharge laser is studied. It is shown that the amplitudes of the turbulent pulsations of the density and refractive index of the active medium depend on the pump method and the degree of saturation by laser radiation and grow with the pump level. Criteria for estimating the effect of turbulence on the quality of the active medium are presented. A model is proposed that relates the build-up of the turbulent pulsations of the gas density and refraction to the heterogeneous heat release in the nonequilibrium active medium. The effect is determined by both the growth of the isobar local temperature pulsations and the ionization-overheating instability. In the case of dc-discharge pumping, the optical inhomogeneity of the active medium may substantially exceed that for the high-frequency discharge pumping.

Spatial structure of focused beams in high-power fiber and CO 2 lasers and peculiarities of their application in cutting

The requirements for quality parameters in radiation of different wavelength (i.e. CO2 lasers and fiber lasers) have been defined so as to perform efficient oxygen-free gas laser cutting of large-thickness samples. The main channels of consumption of radiation power in the cutting process have been considered. It is noted that focused beam divergence not only decreases the cutting speed, but also causes cutting quality deterioration.

Main thermophysical processes in laser beam buildup welding of metal powders

The energy balance of laser beam buildup welding of powders is analyzed. Comparison of the obtained results with the experimental data shows that a significant portion of the absorbed power of the laser beam is consumed for evaporation the of powder. A procedure of selection and optimization of laser beam buildup of powder is proposed. It is established that the thermal conductivity and thermal diffusivity of powder can increase significantly within its melting owing to subsequent formation of thermal contact between the melt and underlying layer of powder particles. The range of the Péclet numbers corresponding to high efficiency of laser beam buildup welding of powders is determined.

Influence of saturation of diode pump radiation absorption in YAG:Yb+3 crystal on parameters of planar waveguide lasers

A method has been devised for calculating the energy parameters of generation of planar YAG:Yb3+ lasers, with regard to saturation of the absorption of pump diode laser radiation with a wavelength λ = 940 nm. It has been shown that nonlinearity of the pump absorption coefficient can substantially reduce the small-signal gain at the transition with a wavelength λ = 1030 nm. It has been found that pump saturation influence on the energy efficiency of planar lasers and power amplifiers is considerably weakened in the field of intense laser radiation.

Thermophysical parameters of additive gap welding with the laser cladding of powders

The simulation and optimization of the main process variables of gap welding with the laser cladding of metallic powders is considered. The adsorption coefficient of powdered particles as a function of particle radius is analyzed for powder feeding via a metering unit. Optimum particle velocities and the weight flow rate of the metering device are determined. Preliminary experimental results are presented.

High-power high beam-quality multi-waveguide CO2 amplifiers

The results from modeling the energy characteristics of a multi-waveguide power amplifier are presented. The optical schemes and calculations for the most promising circuits of multichannel waveguide CO2 amplifiers are given. The amplifying system itself removes the problem of phase locking in individual channels of multichannel systems. The experimental results from the synchronization of arrays of multichannel waveguide CO2 lasers allow the production of high-power (up to 15 kW) high beam-quality multibeam lasers. Technological lasers with such properties have yet to be produced anywhere in the world.

Creation and experimental study of a planar solid-state laser based on a YAG:Yb3+ crystal with diode edge pumping

The results from calculations and preliminary experimental investigations of a solid-state laser manufactured in the form of a plate 15 × 10 × 0.3 mm in size and made of YAG:Yb3+ crystal with two-side diode edge pumping with a total power of 600 W at a wavelength of 940 nm are presented. Both stable and hybrid stable–unstable resonators are used in the experiment.

Spatial structure of focused beam of a high-power fiber laser

The spatial characteristics of the focused beam of a fiber 2 kW laser have been measured. The problems of matching this beam structure, greatly differing from the Gaussian form, with technological operations have been considered.

Mechanism of plasma generation under focused beam effect on metallic surface in laser welding

Numerical modeling of the process of thermal ionization associated with the interaction of laser radiation and metal target was performed and the temperature dynamics and the plasma absorptance were obtained. Threshold values of temperature for the appearance of the thermal instability and near-surface optical plasma generation have been derived. The processes in near-surface laser induced plasma in specific conditions of laser welding are under consideration.