The basic results of both the experimental investigations and the numerical simulation of the energy characteristics of the electric-discharge pulsed CO laser have been presented for the wide range of the active-medium temperatures.

An rf-excited gas-dynamically cooled carbon monoxide laser with unstable resonator (M equals 2) has been developed. The extracted laser beam shows an astigmatic phase distortion which is corrected by use of an extracavity cylindrical mirror. A 4.5 kW laser beam with a total divergence of 1.3 mrad is obtained with an efficiency of 9% and a Strehl ration of 0.5. The beam quality is 1.3 times the diffraction limit. First welding experiments on the aluminum alloy AlMgSi1 (6082) show higher penetration depths compared to carbon-dioxide and Nd- YAG laser welding at the same power level. This is a result of the smaller focal spot size with the CO laser leading to higher intensities in the welding zone. The aluminum weld seams obtained with the CO laser are very homogenous and regular at the surface in contrast to the weld seams obtained with the CO laser. The process parameters in CO laser aluminum welding can be changed in a wide range. This is a consequence of the shorter 5 to 5.6 micrometer wavelength compared to the carbon-dioxide laser resulting in a reduced beam- plasma interaction. Spectroscopic investigation of the CO laser induced aluminum welding plasma show a strong decrease of the intensities of Al (II) lines and no appearance of Al (III) lines as in case of carbon-dioxide laser welding of aluminum.

A compact sealed off metal-ceramic single-mode laser with an unstable-waveguide cavity has been made, which can use some active media (CO, carbon-dioxide molecules and Xe atoms). The output power per unit length is higher by a factor of 2...4 than in lasers with a round or square channel and a stable resonator.

Results of investigations of a slab waveguide rf-excited carbon-dioxide laser are presented. Laser output power of range 200 W and efficiency about 10% in a beam with near-diffraction- limit divergence has been achieved. In the repetitive-rate mode, the pulsed power was more than twice as much as the average one in the cw mode. After beam shaping telescope, the total beam divergence of 2 - 3 mrad at the 0.8 power level has been obtained. A codes package of computer simulation of cw slab rf-excited diffusion-cooled carbon-dioxide laser was created. Comparison of calculated and experimental data has been fulfilled.

Application of an intracavity absorption cell gives the opportunity to increase essentially the output power sensitivity to modulation of losses at the frequency of relaxation oscillations up to theoretically infinite value.

The influence of carbon-dioxide impurity within the laser medium on energy and spectral characteristics of pulsed chemical HF and DF lasers working on chain process has been experimentally investigated. An increase of the concentration of the carbon-dioxide impurity within the laser medium from 0.1 up to 0.6% caused the five-fold reduction in energy and in suppression of generation of about 50 spectral lines of six high bands. The sensitivity of the energy characteristics of the HF laser to the change of the carbon-dioxide concentration was an order of magnitude smaller than for the DF laser, in this case the appreciable changes in the HF laser spectrum were not observed. It is shown, that at low carbon-dioxide concentration (less than 0.1%) the achievement of equal specific output energies per HF and DF molecules is possible.

A waveguide carbon-dioxide laser amplifier with combined excitation by rf and dc discharge was investigated. Dependences of small signal gain on input rf and dc power and gas pressure are presented. A maximum gain 20.9 (DOT) 10^-3 cm^-1 was achieved with a pressure of 75 Torr, total input specific power about 90 W/cm³ and reduced electric field strength of 6 (DOT) 10^-16 V (DOT) cm². Conditions of keeping high gain level have been determined.

The method of frequency conversion based on the use of nonlinear crystal as an output coupler of laser cavity has been proposed and experimentally tested. Frequency doubling characteristics of such a nonlinear output coupler have been studied. It is shown that the second harmonic generation efficiency of a TE carbon-dioxide laser output in this case is several times higher than for traditional focusing methods at the comparable energy parameters of the fundamental frequency radiation.

A transverse radio frequency discharge excited carbon-dioxide slab laser has been operated with a hybrid waveguide/confocal resonator to produce an output power of 46 W. The active volume of 2.5 multiplied by 27 multiplied by 270 mm³ consists of a single discharge section with one cable feed. A spatial structure of radiation is presented.

The aim of the work is to study the performance of laser operating with Ar-CO-O₂, Ar- CO-N₂-O₂ mixtures. Generation characteristics and active medium parameters are analyzed and compared with ones obtained in the mixtures, containing He instead of Ar.

Fundamental experiments using a phased array MOPA (master oscillator with power amplifier) system configuration, composed of the multi-dither COAT (coherent optical adaptive technique) system and two MOPA chains, were carried out to evaluate the validity of the COAT system in the MOPA configuration. It was shown experimentally that phase-locking of two carbon-dioxide laser beams in the MOPA configuration can be achieved by using the adaptive mirror of the multi-dither COAT system.

The pulsed mode generation in HF and DF optical resonance transfer laser (ORTL) has been obtained. The maximum pulsed laser output energy density of 0.13 J/cm³ (DF) corresponded to 37% of absorbed energy conversion was achieved.

The gas close cycle discharge chemical laser using SF-6)-H₂ mixture is described (repetition rate - 150 Hz, single pulse energy - 150 mJ). The impurities limiting lifetime of the filter-equipped laser are identified. The achieved lifetime was close to 300,000 pluses.

A cw supersonic chemical HF laser with dichroic mirrors and external cavity has been investigated on the first overtone regime. The most intensive line P_2-0(4) output power was greater than for any fundamental component.

We consider the performance of high repetition rate XeCl excimer lasers by analyzing the constraints of the discharge parameters, the discharge technique, the shock wave formation and the scaling laws with respect to discharge dimensions and gas densities. It is shown that for high repetition rate the overshoot and charge mode are most suitable because of their lowest amount of fast switching energy that falls within the specifications of commercial long life thyratrons. Fast switching is not only required for better discharge quality but it also limits the heat dissipation of the saturable ferrite switches. An analysis is given of the shock wave development and its consequences on high repetition rate operation. It is found that the shock wave length relative to discharge width is independent on discharge volume. It depends only weakly on the discharge energy. The shock strength for a given discharge energy is inversely proportional to the initial gas density. Shock front disturbances will spread evenly as the shock propagates. For a homogeneous discharge they disappear roughly after a distance equal to the discharge width. With the present analysis scaling laws are derived which state that for optimized conditions the output power depends only on the blower capacity and on the square of the gas pressure.

A new generation of primary national wavelength standards using an intracavity saturated absorption of ¹²⁷I₂ at 633 nm is reported. Relative frequency stability of (2-3) multiplied by 10^-14 and a reproducibility level of about 3 parts in 10¹³ for 1 - 2 months have been demonstrated for the first time in the visible range. One of the key features of the new standards is a very accurate electronic servo-system based on a digital lock-in technique, which is characterized by frequency offsets much smaller than the shifts resulting from asymmetry of iodine resonances. For the standard with an 'ideal' iodine cell, a set of specially selected frequency dependencies have been measured with a low uncertainty level. This set seems to be sufficient for the on spot checking if the operation of a laser standard is normal. A new parametric tuning technique of the laser cavity has been realized, giving important improvement in the reproducibility of the standard. Results of international comparisons of the new wavelength standard performed at the Physikalisch-Technische Bundesanstalt, Germany (PTB) and the Bureau International des Poids et Mesures (BIPM) are reported. In BIPM comparisons, the frequency difference between the standards was found to be 0.7 kHz (much less than the usually reported reproducibility level of these standards). The frequency repeatability for four days of measurements was less than 1 multiplied by 10^-13. In the PTB comparisons, several iodine cells were tested in the new standard, and a correlation between the spacing of the iodine resonances, gas contamination in the cell, the output frequency of the laser was established.

Argon laser lines in the violet-blue spectral region have been studied experimentally. Cw generation has been demonstrated on a set of close lines: 438.4, 437.6, 437.1 and 436.2 nm, in particular, cw lasing on 438.4 and 436.2 nm being observed for the first time. Cw lasing has been also observed on 418.2 and 431.0 nm lines. The highest output appeared on the 438.4 nm line, which corresponds to weak quartet-doublet transition 4p⁴S_3/2 -4 s²P_3/2. Determined are the gain 10^-4 cm^-1, saturation parameter 6.5 kW/cm², and the Einstein coefficient of this line. High power fundamental TEM₀₀ mode operation has been achieved. It has been shown that a comparatively high output power is extracted due to a high pumping rate of the studied quartet level, comparable to that of the known 514.5 nm argon laser line.

The results of the experimental and theoretical DSPIL modeling are presented. The parameters of the generation pulse (energy, duration, delay time) are measured for the series of perfluoriodide laser compounds under pumping conditions imitating the space solar radiation spectrum. The time dependence of the radiation spectrum was measured for the pumping pulse. The spectrum of this pulse corresponds to the ABB spectrum with temperature 6000 K in the pulse beginning and 3500 K in the end. The generation energy ratio (E₁₀/E₁) in repeatedly pumping pulse action without the active laser medium change was measured in this experiment. The empirical linear dependence between quantities 1n(E₁₀/E₁) and 1n(k₃/k₄) is received, where E₁ and E₁₀ are the energies of generation pulse after first and tenth pumping pulses. The mathematical model of DSPIL, containing the main kinetical processes description, is developed. The computing evaluation of the energy characteristics of DSPIL are presented.

The considerable progress in understanding the free electron lasers (FEL) physics made it an actual task now to find the ways of practical FEL application. The broad wavelength FEL tunability allows it to be used in laser chemistry or for fundamental spectroscopic research. But there is a problem -- the radiation line of the undulator, the key element of the FEL, is too broad for some chemical or spectroscopic application. The wavelength width may be narrowed by using frequency selective elements, e.g., the planar quartz plates may be inserted in the optical cavity or may be used as the external selective element. In the frame of the tentative agreement between OKB Granat and Duke University FEL Laboratory the design of broad band tunable Fabry-Perot cavity for infra red range was developed which allowed the user to select narrow spectral line and to monitor its parameters during operation. There are a lot of Fabry-Perot cavities with removable elements on the base of a set of invar or quartz rings which allows changing of the basic frequency in a small range. In this paper we propose the design of broad band tunable Fabry-Perot cavity for infra red range from 2 to 4 mkm with mode variation from 40 to 240 GHz.

The paper presents the experimental results of evaluating the output characteristics of TLA- 600 carbon-dioxide laser with axial turbulent gas flow, as well as the results of numerical modeling. The output characteristic and spatial distribution of laser beam were measured with regard to specific energy input, working mixture pressure, active media length and output mirror reflection. The paper presents the results of experimental and theoretical study and design decisions on a succession of similar type industrial carbon-dioxide lasers with fast-axial gas-flow and dc discharge excitation of active medium developed at NICTL RAN. As an illustration, characteristics of the TLA-600 laser are cited.

The measurements of carbon-dioxide-laser radiation scattering in the atmosphere were carried out in the angle range of 7 - 65 degrees under the various weather conditions. The empirical parameters of the indicatrix of scattering were evaluated.

The photoacoustic gas analyzer utilizing an industrial carbon-dioxide waveguide laser was presented to quantitatively determine low concentration of gaseous pollutants in real air. The PA resonant H-type cell design was described. By analyzing the dependence of the PA signal on a modulation frequency, the most suitable acoustic resonance was chosen for practical use. The spectrophone characteristic constant A was determined for various carbon-dioxide laser lines which coincided with air pollutants absorption lines. The schematic diagram of the full- automatic PA gas analyzer was considered, and the interconnection of its units was outlined. It is shown that PA gas analyzer concentration characteristic is linear in a wide concentration range overlapping three orders of magnitude; pollutants detection threshold values are considerably less than their utmost admissible concentrations in air of the living zone. An idea of using Stark's modulation at atmospheric gas pressure analysis is examined.

Flows study methods by selecting of the spatial-temporal structure of the scattered light are discussed. The Doppler anemometry with adaptive spatial-temporal selection and visualization of velocity vector resides in communicating the measurement channels on line with discretization of the process by a flow of scattering particles. As a result it makes it possible to increase considerably an energy flow density in a probing field under the same laser radiation power. A color visualization of optical density fields in real time based on polychromatic Foucault-Hilbert transformation is described.

The paper presents two carbon-dioxide laboratory laser systems that were designed for a large number of heterodyne detection experiments, as small signal detection, target range, and velocity measurements, Doppler shift examination, frequency difference measurement, etc. These systems were performed in cooperation with the Institute of Quantum Electronics from the Military University of Technology, Poland.

The results of multi-purpose autodyne cw carbon-dioxide lidar design for monitoring of atmospheric and polluting gas concentrations and determination of optical and dynamical characteristics of reflectors are reported.

The paper presents some results of stratospheric aerosol sounding obtained during ground- based correlative measurements in the framework of the NASA LITE program at the Siberian Lidar Station (Tomsk) in September 1994.

The proposal about using COIL not only for industry but also for reverse-industry such as decommissioning, or the rescue operations for disasters is made and the possibility is discussed in this paper.

The temperature profiles in the altitude range of 20 - 70 km using lidar returns at the two wavelengths of 353 and 532 nm in the stratosphere and mesosphere are determined. Analysis is conducted of accuracy characteristics of temperature reconstruction by real lidar returns.

We propose the code for simulation of laser radiation propagation through turbulent and nonlinear atmosphere in the wave and ray approximations. The code has graphic shell and convenient interface.

We have investigated the transient luminescence of silicate glasses irradiated with laser UV. The characteristic time of luminescence decay at room temperature is about 1 mks. We have found a dependence of the intensity and the spectra shape on geometry of irradiation and the sample thickness. We explain this dependence as a result of the luminescence radiation reabsorption with transient radiation defects. On this bases we have developed a model that gave us opportunity to calculate the transient absorption spectra, associated with that defect. These spectra significantly differ from stationary absorption spectra induced with multi- impulse irradiation.