High power XeCl laser system and experimental results of diffraction limited laser beam amplification are described. Beyond the preamplifier, the 5 cm X 6 cm laser beam contained 50% of the radiation energy in the diffraction core. At the output from the system an irradiation brightness of 2 X 10¹⁴ W/cm^-2cr^-1 was obtained. Minimum divergence near 0.05 mrad of output beam was restricted to turbulence of air and optics elements. A numerical model of the amplification of the radiation, taking onto account the influence of the amplified spontaneous emission, was developed.

There are several key engineering and physical issues for the development of Krypton Fluoride driver for Inertial Fusion Energy Program. In the frame of this program we have performed experiments with e-beam-pumped KrF laser installation GARPUN on the transportation of relativistic e- beams through aluminum-beryllium and titanium foils and compared them with Monte Carlo numerical calculations. It was shown that 50-micrometers thickness Al-Be and 20-micrometers Ti foils had equal transmittance of 75% for approximately 300 keV, 50 kA/cm², 100 ns e-beams, being lower than calculated one. In contrast to Ti foil, which surface was strongly etched by fluorine, no surface modification and no fatal damages were observed for Al-Be foils after approximately 1000 laser shots and protracted fluorine exposure. It was shown that applied magnetic field of approximately 1 kGs significantly reduced electron scattering both across and along laser cell at typical pumping conditions with 1.5-atm pressure working gas. The energy fluence of scattered electrons fell down from approximately 100 mJ/cm² to approximately 1 mJ/cm² per pulse at 8.5-cm distance from the boundary of injected e-beams. Without magnetic field the scattered electrons were spread up to 20 cm, thus strongly irradiating optical windows and being a cause of additional induced absorption of laser radiation.

The results measurements integral intensity luminescence laser transmittance B yields X (353 nm) and C yields A (480 nm) excimer XeF depending on pressure buffer gases are presented. The constants quenching K_B, K_C and transfer K_BC for thirteen connections are measured. Twenty two constants are obtained for the first time. The simplified model an vibrational relaxation in the state B, obtained ratio T_vib^-1 equals a + b(DOT)lnp is confirmed experimentally.

Nonlinear reflection of focused laser radiation (222-413 nm, H₂-SRS-converted depolarized XeCl-excimer laser output) in Xe-containing binary gas mixtures and cryogenic solutions was studied. The effect of strong enhancement of unsaturated reflectivity, especially pronounced and frequency selective for admixture of Cl, Br-substituted hydro-carbons (CF₂Cl₂, CF₃Cl, CF₃Br) was observed, whereas no effect was found when fluorides (CF₃H, NF₃) or oxygen were added. For linearly polarized (lambda) equals 308 nm radiation reflectivities increased twofold up to approximately 0.8 at the intensity approximately 5 (DOT) 10¹⁰ wt(DOT)cm^-2. Nonlinear reflection at (lambda) equals 308 nm in low-temperature solutions of Xe (20% mol) in LAr (at 140 K) and LKr (at 170 K) was observed and analyzed. Close to second order pump intensity dependences of reflection, photo-acoustic signals and secondary emission were found.

Transmission dependencies of optical materials samples BaF₂, Al₂O₃ and CaF₂ (the infrared range sample) from KrF-laser radiation intensity with pulse duration of 85 ns are experimentally received. From these dependencies, two-photon absorption coefficients at laser wavelength 248 nm are found which for the appropriate materials are equal to 0.5 +/- 0.2, 2 +/- 1 and 30 cm/GW. Laser damage thresholds of the surface and volume of the investigated samples at 248 nm are also determined.

In the work two models describing interaction of UV laser radiation (LR) with ionic crystals are considered. In the first version the wavelength of LR lies in absorption region of F centers, in the second--it is in a short-wave area of H centers absorption wing. Is shown, that the photodissociation in crystals of F₂^- complexes on two holes is the effective mechanism of defects formation in a crystalline structure. The account of these and other electronic excitation relaxation processes in models allows to explain many experimental results of LR action on ionic crystals.

Continuous-wave generation is demonstrated of the anti- Stokes Raman laser in new (Alpha) scheme ArII 3d'²G_9/2 yields 4p'²F_7/2 yields 4s'²D_5/2 with long- lived start and final levels. Red pump radiation with wavelength (lambda) _p equals 611 nm from a dye laser that excites transition 3d'²G_9/2 yields 4p'²F_7/2 is converted into the blue radiation at (lambda) equals 461 nm (4p'²F_7/2 yields 4s'²D_5/2) with efficiency of about 30%. The tunability range spans more than +/- 10 GHz around exact resonance, which is five times as wide as the Doppler contour. The output frequency (omega) is found to depend linearly on the frequency (omega) _p of the pump field: (omega) approximately equals (omega) _p(lambda) _p/(lambda) . A sharp peak of output power is observed in the detuning curve at the exact resonance instead of well-known two-photon dip. The model is proposed that includes ionic scattering in plasma and interaction of the running pump and standing output waves. The derived formula offers an interpretation of the observed peak.

Over the past six years we have been conducting detailed studies of a family of closely related supersonic mixing nozzles. These nozzles have performed well in experiments with the VertiCOIL laser. Subtle design changes in these nozzles lead to highly predictable results when compared to the complete CFD calculations for the three designs under study. Our conclusion is that mixing within the jets very near the nozzle throat with nitrogen diluent provides a more efficient lasing process.

The chemical oxygen-iodine laser (COIL) is one of the most promising and extensively studied chemical lasers. Nevertheless, the mechanisms governing its operation are not yet fully understood and efforts are underway to find better singlet oxygen chemical generators and improve oxygen/iodine mixing schemes. The latter efforts are briefly reviewed and recent results of parametric studies of an efficient supersonic COIL operating in our laboratory are presented. The laser is energized by a jet type generator, operating without primary buffer gas and applies simple nozzle geometry and mixing of iodine and oxygen at or after the critical cross section.

A possibility of the amplification of image brightness by the active medium of the photodissociative iodine laser have been demonstrated. The brightness of the test-object image with spatial frequency of 10 mm^-1 was amplified 1600 times for Q-switch lasing action and 250 times for free- running one. The contrast of amplified image was equaled 0.8 in both occasions. The smallest input signal achieved the level of 10^-13 J per pixel.

We consider the possibility to design the fullerene-oxygen- iodine laser with optical pumping (solar, particularly). It is assumed that singlet oxygen is formed at pass of molecular oxygen through (and interaction with) mixture of lower and higher fullerenes in the triplet metastable state obtained at illumination of fullerenes. The presented results of estimates by a photokinetic model show the opportunity to reach the efficiency of the FOIL with solar pumping at the level of several tens of percents. We present the results of experimental and theoretical studies of singlet oxygen yield at interaction of optical pumping with fullerene in solutions. Laser radiation with wavelength of 532 nm and wideband lamp radiation for imitation of solar radiation were used as pumping.

The commercial lasers with power 20 kW and up are created by scaling of well-developed electrodischarge kilowatt CO₂ laser with circulating of gas. However, there occurs two negative moments: loss of the optical beam quality and significant increase of laser cost. The first moment is connected not so much with increase of laser beam path between resonator's mirrors as with quantum efficiency of CO₂ molecule, which is 0.41, and also with conversion of irremoved vibrational energy to heat in a resonator. The cost of lasers with power 10 kW and higher is considerably increased in scaling of kilowatt CO₂ lasers. This is associated with the necessary increase of consumption of active medium, resulting not only in a change of circulating system, but in a change of regeneration system, source of power supply, cooling system, system of extracting radiation, etc. as well.

For the various pumping rates and for the various heights of the gap were calculated the average value of the small- signal gain and its profile across the gap. For the high power slab CO₂-lasers, RF-excited at 40.68 MHz, were analyzed the ranges of their geometry parameters vibration, providing for the possibility of diffraction limited performance. In theory and in experiment was shown the possibility to select the basic waveguide mode of radiation.

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.

We describe the design and construction of an efficient tunable CO₂ waveguide laser which was used for thermal graving of predigitalized images over polymeric materials. The small internal diameter of the cylindrical waveguide allowed the laser operation in high pressure regime ranging from 50 Torr to 100 Torr, which gives higher gain per cavity length. The operation of the laser at 80 Torr with the gas composition CO₂:N₂:He:11:9:60 gave a 400 MHz laser linewidth. For the proposed laser design we used an electrodes configuration which provides a symmetric discharge. The laser cavity, divided into three pieces, show great light coherence.

Physical processes proceeding over the active electrode surfaces and their influence on a spatial plasma homogeneity of the volume discharge as well as the energy parameters and the resource of sealed-off pulse-periodical TEA-CO₂ lasers have been investigated. Microstructures of the active electrode surfaces which lead to the increase of autoelectronic emission have been found to be formed under the influence of the volume discharge plasma and the products of plasma chemical reactions. The increased values of these currents initiate the formation of local channels in the cathode area of a volume discharge and initiation complete transition of volume discharge into a local one. The electrode materials, which provide the formation of stable volume discharges are determined and a maximum resource of sealed-off TEA-CO₂ lasers is achieved.

The aerodynamic windows are intended for a high power extraction from the gas laser optical cavity, where the pressure is much lower than environment pressure. The main requirements for the aerodynamic windows are to satisfy a low level of optical disturbances in a laser beam extraction channel and an air leakage absence into the optical cavity. One way of the optical quality improving consists in density drop decrease by working gas heating. Optimum heating of the jet gas improves the optical quality of aerodynamic windows. In this case they became useful for powerful DF, HF chemical lasers and COIL. Registered aberrations of the aerodynamic windows are insignificant for divergence quantity of the laser beams with wavelength for 1 to 10 microns.

The conditions of forming the spatial homogeneous volume discharges in N₂:He; Xe:He, Kr:He and Ar:He mixtures at total pressures of P equals 0.5 - 1.5 Atm and at pulse repetition rates up to F equals 7 kHz are investigated. The influence of macro- and microinhomogeneities of the volume discharge plasma on the maximum pulse repetition rates and average radiation power of TEA-lasers are determined. A maximum value of the average radiation power of P_AV equals 20 W on molecular nitrogen ((lambda) equals 337 nm) and P_AV equals 28 W on transitions of neutral atoms of Xe ((lambda) equals 1 - 5 micrometers ) are obtained.

Humanity can struggle with the small dangerous cosmic objects in our time and its parameter knowledge are needed. A present paper deals with prospects for the perspective of the laser methods applications for a dangerous asteroids discovering and a remote sensing and for the course correction systems of the influence expedients. The cosmic IR lasers will be used for remote sensing measurement of the various cosmic objects parameters: dimensions are more than 50 m, velocity is more than 10 km/s. The laser methods have the good perspectives among a large fleet of diagnostics technical means. The more effective CO₂-laser parameters were defined for the solar systems smaller bodies velocity analysis. The laser is supplied with modulated laser radiation and an automatic tuning optical system. The CO₂-lidars are needed for the asteroids detections and remote sensing at the distances of 30,000 km to 1 Mkm. A laser Doppler anemometer method with adaptive selection is used. The power calculations were made for the various asteroids in a cosmic space. The possibilities are estimated for remote sensing and for the course correction systems of the influence expedients also. The such system must be good for the distances nearby 12600 km, as the asteroids velocity can be more than 70 km/s.

With the aim of a parameters control of multiwave lasers the influence of the competition of CO₂ molecule rotational- vibrational transitions on the original two-channel technique has been investigated experimentally. The strong competition of transitions is observed only at two-wave generation on lines of one band, for example, 00⁰a- 10⁰0. At the two-wave lasing on lines of various bands the competition of transitions can be essential weak.

The results of an experimental research of action of the intensive mid IR-range pulse-periodic laser radiation on VO₂-mirrors are represented. The damage thresholds of VO₂-mirrors are defined for pulse-periodic and continuous radiation and the analysis of the mechanism of their destruction is carried out. The results of numerical simulation of dynamics of switching of VO₂-mirrors under the action of pulse-periodic radiation are presented.

Several original schemes for intracavity frequency doubling of CO₂ laser radiation (TEA and cw systems) in AgGaSe₂ nonlinear crystals have been proposed and studied experimentally. Computer modeling was used for optimization of the optical schemes and cavity parameters. The enhancement by several fold in conversion efficiency was achieved for intracavity SHG in comparison with traditional schemes. A 60% peak power efficiency and 15% energy conversion efficiency has been obtained with a TEA CO₂ laser. More than 100 mW at 5 micrometers was generated in the crystal with L equals 17 mm, which is a record output for SHG of a cw CO₂ laser. This output is more than 10 times higher than 5 micrometers power measured with standard focusing the CO₂ laser beam.

Detail analysis of active medium flow structure is presented. Schlieren method photography of flow is processed to reconstruct parameters both stochastic and order phase components. Properties of random part including correlation function, spectrum of spatial frequency, scale of turbulence, are determined by digital filtering. It was possible to compare influence of random and regular phase distortions on radiation divergence structure.