The brief review of the modern state of the problem is given. Experimental results on CW lasers with total efficiency 50 percent and QCW 2D arrays with power density 1 kW/cm² are presented. The reasons of the output power limitations are considered. The numerical model of thermal regimes at QCW and CW operations and the model of total efficiency were used in respect of laser resonator and array design optimization. The nearest prospects of diode laser performance improvement are discussed.

The repetitively pulsed Nd:YAG laser with dynamic cavity formed with participation of dynamic holographic gratings induced in Nd:YAG laser crystal and Li:F absorber has been investigated. The generation regimes and technological opportunities of this Nd:YAG laser were studied. High spatial brightness of radiation at diffraction limited divergence has allowed to carry out effective punching of calibrate holes in different materials with a diameter up to 15 micrometers and maximal depth up to 20 mm.

Generation dynamics of powerful single-mode Nd:YAG laser system with optically coupled cavities at passive Q- switching by a crystal LiF:F₂ is described. The mechanism of occurrence of high-energy nanosecond pulse trains at CW-pumping is established. The regimes of generation having character of low-frequency cavity dumping of the compound resonator are investigated. Within the limits of 10 percent the qualitative and quantitative concurrence of calculation and experimental parameters of radiation by average power up to 100 W and peak power more than 400 kW is obtained.

We define the occurring conditions of Talbot effect for 2D periodic wave field of general configuration. Corresponding distances of self-reproduction are derived by the simple analytical expression. Dynamics model of the collective generation of waveguide laser array with diffraction coupling in an external cavity is offered. On its basis we calculate the thresholds of collective generation, the selectivities of external cavities, and field distribution in far-zone for 2D arrays of square and triangular filling. The effect of array irregularities on the spectrum of collective modes is discussed.

Under conditions of mutual coherence of the amplified laser beams the power and axial brightness amplification for the two-channel version of the amplifier are experimentally measured. Numerical investigations of the amplifier radiation characteristics are carried out including a random spread of the parameters of separate channels both for the two-channel and multichannel amplifier.

The polarization characteristics of radiation of the industrial transverse-flow 5 kW CO₂ laser have been studied. The conditions for generation of radiation with linear polarization and for the regime of random change of its direction have been determined. The interrelation of radiation polarization characteristics with the parameters of the laser of this type has been established.

The beam characteristics of the 2.4 kW industrial CO₂ laser with the continuous current discharge and transverse gas flow have been studied depending on the main parameters of the telescopic resonator with the convex variable reflectivity mirror. The three-fold reduction of the beam divergence and the power decease only by 15 percent in comparison with the conventional stable resonator were obtained. Besides, the high degree of matching of the parameters of optical resonator and gas discharge chamber was reached.

The chemical oxygen-iodine laser (COIL) is a scaleable high power laser promising for industrial applications. The principles of singlet oxygen generation in the jet type singlet oxygen generator and COIL operation are considered. The progress in high pressure jet type singlet oxygen generators allowed to develop the compact highly efficient COIL. The different types of efficient mixing schemes were tested in COIL based on the high pressure jet singlet oxygen generator. The preliminary cooling of active medium via mixing of oxygen with cold buffer nitrogen gas result in high efficiency operation of the small scale COIL with subsonic gas flow in the laser cavity. The project of COIL with high pressure of oxygen in laser cavity is discussed.

The stable form of the pulse train is naturally reproduced in ultrashort-pulse lasers with low amplification in the active media. In lasers with a high amplification factor per pass an instability of train structure is observed with stable full output energy of radiation. The paths for stabilization of train structure by the use of regenerative amplification or stabilization of amplification of an active media with accuracy of 0.5 percent are offered.

The presented laser is a brand new elaboration of the compact gas laser with longitudinal excitation. This development has no analogues and is protected by the patent of Russia. Its main features are: monoblock construction of the had, internal mirrors, optical contact, small size and weight, long term of work and storage.

An acoustooptic system with optoelectronic feedback providing laser beam direction stabilization is studied. Different modification of the system based on isotropic and anisotropic diffraction of light are considered. Influence of the acoustooptic selectivity on the operating angular range and the stabilization coefficient is analyzed in detail. Results of experimental investigation of the system based on a paratellurite crystal cell are presented as well.

The new procedure of complex laser resonator simulation with essential phase inhomogeneities, misfigured mirrors and intracavity adaptive control is presented. The procedure is based on the numerical definition of a cavity eikonal through calculations of rays trajectories with Feder formulas. The numerical results are given for unstable resonator with an intracavity segmented mirror.

The paper presents the results on investigations and development of multichannel waveguide CO₂ laser with diffusion cooling of active medium excited by discharge of audio-frequency alternating current. The description of high-power single-mode CO₂ laser with average beam power up to 1 kW is presented. The result of measurement of the laser basic parameters are offered, as well as the outcomes of performances of the laser head with long active zone, operating in waveguide mode. As an example of application of these laser, various capabilities a description of the developed medical system 'Genom' used in the transmyocardial laser revascularization (TMLR) procedure and clinical results of the possibilities of the TMLR in the surgical treatment are presented.

In this article the dynamic model of the process of the laser welding with deep penetration based on the variation principles is presented. The model takes into account melting flow, wave motion on the cavity surface, melting viscosity, bubble pressure, recoil pressure and radiation parameters. The model predicts self-oscillation character of the cavity behavior in welding, moreover the cavity oscillations are stochastic in general case.

A qualitative analysis of the latest published result of investigations of deep laser beam-material penetration, with beam intensities in a range of 10⁵-10⁷ W/cm², is performed. The processes of keyhole formation and of penetration laser welding are considered. A review of some possible hydrodynamical melt surface instabilities is given. Nonlinear stage of these instabilities can be accompanied with melt droplets injection into the beam illuminated volume. A possible mechanism of periodical relaxational melt transfer in the process of keyhole formation and penetration welding is discussed. Vapor bursts generated by intensive evaporation of the melt droplets may be responsible for this mechanism.

The mechanisms are analyzed that rely the depth of melted zone and kinetic growing parameters of the vapor-gas channel with spatial and time characteristics of pulse radiation of millisecond range of duration. Conditions of experimental realization of the effect of laser radiation intensity on raising the bottom of the growing vapor-gas channel are described. Optimal parameters of the radiation ensuring the maximal depth of the melting zone at the specified energy input are given.

The theoretical basis for the self-consistent numerical simulation of laser penetration welding is presented. The model is based on the equations of energy transport and of equilibrium at the free surfaces for balancing vapor pressure, capillary pressure and a correction term. The correction term allows balancing the metal volume taking into account thermal expansion and shrinkage during welding and the gap width between the parts to be joined. The model was verified with welding experiments on steel and aluminium alloys. The uncertainties of the simulation and verification of the cross-sectional geometric parameters of welds are investigated. The associated software DB-LASIM is presented and its industrial applicability demonstrated for the butt and overlap joints.

Non-stationary mechanism of melt removal in gas-assisted laser cutting is analyzed. Characteristic time of the process is determined. Possibility is shown to enhance significantly the cutting energy efficiency by conforming the repetitively-pulsed regime with the time obtained.

A theoretical model describing the dynamic behavior of the gas-vapor cavity (GVC) in the processes of laser beam deep penetration into condensed medium is presented. Non- equilibrium evaporation from the channel surface, non- stationary hydrodynamical processes and heat conduction in the melt are considered. Linear stability analysis of the GVC shape is performed. The conditions of a cavity instability and their relations with materials and irradiation properties were obtained. The frequencies of the cavity oscillations are calculated.

Results of experimental and simulation investigations of hydrodynamic processes of auxiliary gas flow out of nozzles nd stream of products of erosion from the cut slot using laser cutting are presented. Practicability of mathematical modeling of the processes by solving Navier-Stokes equations using simulation programs 'APTEK' and 'PHOENICS 1.4' is shown. Calculation results were validated on full-scale models in hydrodynamic test loop tunnel. Results of modeling then were used in situ, when compressor valves were manufactured using laser cutting of sheets of stainless steel 30X13. Laser cutting was carried out using laser technological unit created on the basis of pulse solid state laser LIT-100M.

Mechanisms of air flow in a cut produced by a gas jet intended for melt removal in gas-assisted laser cutting is studied. Special consideration is given to the following cases: starting point of cut from the center of plate and starting point of cut from the edge of plate.

The results of experimental investigation of cutting kerf characteristics of workpieces of electrical steep depending on nozzle pressure p_n of inert gas and cutting speed v_c are presented. It is demonstrated that the kerf width decreases with increase of v_c as v_c^-1/2 and the period of striations on lateral surface decreases with increase of p_n as p_n^-1/2. The obtained relations are in a good agreement with fulfilled estimations.

The results of experimental investigation of distributions of melt material remaining under workpieces depending on the nozzle pressure p_n are presented. It is demonstrated that there exist two critical pressures p_n,1 and p_n2 that separate the regions of full confinement, partial removal and full removal of melt. The estimations of p_n,1 and p_n,2 based on the relations between the time of melt gathering through the cutting front and the Rayleigh instability development are fulfilled. The obtained experimental results are in a satisfactory agreement with the performed estimations.

The 3D theory of laser cutting is presented. The efficiency of cutting at different types of polarization is estimated. It is shown that ultimate cutting characteristics at linearity P-polarized beam are essentially worse in comparison with potential possibilities connected with P- wave absorption. The laser cutting efficiency for radial polarized beam is 1.5-2 times more than for linearly P- polarized and circularly polarized beams.

The paper reviews the results of experimental study of punching channels in glass samples by radiation of a single- mode CO₂ laser in the intensity range from 4 10⁴-1 10⁶ W/cm². The effect of pressure of the air flow following in the same direction upon punching velocity has been studied. The threshold conditions of channel formation have been determined by radiation intensity and surplus pressure of the air. The dependence of glass surface tension coefficient on radiation intensity has been estimated. The variation of the surface modulation period by the channel depth has been qualitatively explained on the basis of the model of thermocapillary instability.

The threshold modes of metal cutting by combined radiation of CO₂ laser with a ring TEM₀₁ mode, 800 W power, 200 microns beam diameter and pulse-periodic Nd:YAG laser with a TEM₀₀ mode, 90 microns beam diameter, 80 W average power are investigated. It was established, that improvement of CO₂ laser radiation usage efficiency and narrowing of the cutting channel to Nd:YAG laser spot diameter is caused by tightening of radiation into the narrow channel.

Variation of the angular spectrum of the laser beam transmitted through the hole formed by it in the glass plate 2 mm thick located in the vicinity of focus of the lens placed into the beam, has been experimentally studied. It has been established that this hole manifests itself as a focusing device and possesses the properties of a short waveguide. The dependence of radiation divergence on the relation between the transverse sizes of the hole and the beam at the inlet has been studied.

Investigation results of laser cutting of curvilinear elements of sheet materials with up to 1.0 mm thickness are presented. A possibility of discrete collection of erosion products from different places of the laser cut and the chamber-catcher is shown. Collected samples were investigated by means of Moessbauer spectroscopy and magnetrometry. The optimal condition of the laser cut were determined by phasal composition, dispersion and magnetic properties of erosion products. The regime of laser cutting was considered optimal when providing the finest particles and containing the largest amount to iron oxides. Hydrodynamic and power conditions contributing to laser cutting were determined.

The experience on replacement of the conventional methods of manufacturing thin-sheet parts for aircraft plants in favor of laser cutting is being systemized. In particular, the consideration is being given to the technological problems of manufacturing figured spacers of foil and thin stainless steel having the thickness from 0.05 to 0.5 mm, and ribbed plates of thin corrugated aluminum. The use was made of the automated system built around a 400 W solid-sate YAG laser. The optimum processing conditions were found for attaining the required quality of laser cutting. The peculiarities and technological methods of the specific parts manufacturing are being described.

As a result of experiments and numerical simulation low- threshold ablation of materials under the action of pulsed laser radiation on metals was established. The resulting surface structure with heat insulating fragments contribute to low-threshold evaporation and erosion plasma ignition. Analysis of experimental data on plasma threshold conditions in the wide range of wavelengths and laser pulse lengths has been carried out.

The features of metal composite materials fusion welding are examined and the main defects arising at argon-arc, electron-beam and laser welding of alloys Al-Be-Mg, Fe-Cu-Pb and Al-Pb are revealed. The defects formation mechanisms are indicated and technological welding methods of metal composite materials are developed. These methods allow to prevent defects formation and obtain the welds with required mechanical properties and quality.

The paper deals with the problem of on-line monitoring of the cavity parameters in laser beam welding with deep penetration. On the basis of simplified model of the cavity dynamic behavior a strategy of the cavity depth and average diameter measurements was developed. The possible ways of the technical realization of the measure system are also discussed.

The object of the research is the Al-Mg alloy, the welding problems of which are high deformations of thin-sheet constructions, and refractory oxide film. It is suggested to use laser welding, characterized by low specific heat input and high concentration of energy, with application of some fluxes being developed, which raise the efficiency of the process and decrease the quantity of oxide inclusions in the weld.

Any mechanical methods of fastening of protective washers cannot be used for light series of bearings because of their specific construction. Spot laser welding was proposed in the paper for this purpose. Parameters of the laser radiation were determined on the basis of the requirements to minimization of residual deformation, limitation of cross dimensions of the welds and ensuring sufficient depth of the welds. Experimental technological setup for laser welding of protective washers was created that ensures the quality of laser beam not worse than 10 mm mrad, depth of the welds not less than 0.2 mm at the maximal diameter not more than 0.1 mm.

Our paper reports about YSZ powders by successive evaporation and crystallization in the gas stream. In the laser applied the original method of active medium excitation was used. Efficiency of the laser constructed on the basis of this method reached 22 percent and specific power output at approximately 1 W/cm³. Pulsed regime is proved to be more efficient for active medium excitation and target evaporation than continuous one. Targets made from coarse YSZ powder with Y₂O₃ content of 10.15 mol. percent were evaporated and crystallized in a stream of cleaned air. Cubic-structure YSZ particles were obtained which had a shape close to spherical. Particle size distribution was close to a lognormal distribution with dg equals 10 nm and (sigma) equals 1.75. Specific surface of the powder was up to 70 m²/g, while the Y₂O₃ content reduced to 9.8 mol. percent.

The process of controlled laser sintering for powdered SHS compositions with the bases Ni-Ti and Ni-Al was realized. The optimal parameters of laser effect, under which the reaction of SHS proceeds in controlled regime, were determined. The phase composition of the sintered structure was revealed by the x-ray phase analysis. In particular, it was shown, that the NiTi-material with shape memory effect, perspective for using in medical implantation, is the basis for forming intermetallic phase under laser sintering of Ni_Ti powder compositions.

The possibilities of laser-ultrasonic hardening of surface under checked change of its structural-and-phase composition and residual stresses level were experimentally determined. On high-chromic tool steel in its initial annealed condition it was shown that the harder and deeper zones of surface hardening are formed under the laser-ultrasonic influence. The plastic deformation of surface by the ultrasound influences noticeably the fullness of austenite formation process and hereunder allows to effectively check a strained condition of the surface in the laser influence zone.

Program 'TOOL's' was developed to realize of a new approach to efficiency estimation of the laser heat treatment process. This approach consists in the complex investigation of influence of the laser irradiation and tools operation regimes on hardened tools wear resistance. Algorithm of processing results of the multifactor experiment forms the basis of this program. The program permits to construct the adequate wear resistance model, to conduct optimization of the laser treatment regimes for specific regimes of the tools operation and forecasting its wear resistance using experimental data. The values of hardened tools wear resistance calculated according to the model are in good accordance with the experimental results.

An experimental investigation of influence of laser radiation on the phase composition of carbon-carbon composites with different types of non-graphitizing carbon matrix and fabric fillers was made. It was shown that laser treatment formed a graphite-like structure of material. The process of graphitization is a heterogeneous crystallization. The monochromatic reflectance was measured of carbon-carbon composites within the range of 0.4 to 1.06 micrometers and 10.6 micrometers before and after laser treatment. It was shown that laser treatment causes sharp increase of oxidation of stability carbon-carbon composites in ambient air under elevated temperature.

It has been shown with the help of x-ray researches that the electronic structure of structural components formed in a surface layer of steel during laser alloying differs form that of similar structural components formed in equilibrium conditions. Saturation of a solid solution beyond the limit solubilities during laser alloying leads to some increase of electron localization on atoms. The analysis of distribution of electronic density in an elementary cell of a solid solution shows that some part of atoms of boron is dissolved in a solid solution on the basis of iron by replacement. The nonequilibrium process of cooling after crystallization leads to appreciable change of an electronic structure of boron iron Fe₂B. The comparison of boron iron, formed in equilibrium conditions, with boron iron form a laser alloyed layer shows that in an elementary cell of latter the distribution of electronic density is more dim, that allows to speak about some decrease of a degree of electron localization on atoms.

In work the features of formation of structure and properties of superficial layers are investigated during laser alloying of a surface of low-, middle- and high-carbon steels with the help of the powder composition, consisting from chromium and carbide of boron. The analysis of the obtained results shows that at laser alloying of a steel surface the firm laser layer with the rather homogeneous structure is formed. The structure of this layer consists of considerably oversaturated solid solutions and hardened phases as smallest particles both of carbides and borides of iron and chromium. It is shown, that even the heating to high temperatures down to 900 degrees C done not lead to integration of hardened phases, that speaks about high stability of structure at laser alloying. The high thermal stability of structure provides preservation of high hardness of the laser alloyed layer. The hardness of a surface remains at a level 6.5-7.0 GPa even after heating up to 900 degrees C.

In this paper the thermochemical and hydrodynamic processes at laser nitration of the surface of titanium are studied by means of an experimental unit. Consideration is given to mathematical models of heat distribution in titanium and hydrodynamic processes on the surface of titanium under action of laser radiation.

This article deals with strategic development of laser technology of material treatment. The efficiency of laser material processing is discussed. The structure of laser treatment CAD/CAM systems is suggested. The opportunities of the global network telecommunications allow to provide the wide possibilities to use the system of prediction in the mode of real time.

The paper present the result of long-term investigations of experimental industrial laser complex designed to study the possibilities of applications of high power gas dynamic CO₂ laser in metallurgical technologies for repair and restoration of large scale equipment. Technical and economical aspects of industrial application of such laser systems are discussed.

Consideration is given to the problems of kinematic structure synthesis of systems for transporting laser-robot emission proceeding from the condition of minimization of the number of beam diffractions from rectinlinearity of its transmission and of the position-and-force control of both the mirror adjustment and the optical head movement under the action of external connections of uncertainty or partial assignment of the object being worked.

A four-mirror phase-shift system has been offered for laser technology of metal cutting. The system retains the direction of the main optical axis and allows for aligning the phase difference value in the vicinity of 90 degrees. The performances of the phase-shift system used in the CO₂ laser plant of about 5 kW power are presented.

Our studies on the thermal cross talk of laser arrays with integrated thin film heaters involve theoretical as well as experimental investigations. Comparing the effects of intentional geometrical variations of the device design, we found that the relative thermal crosstalk depends critically on the distance between the active area and the film heater. The most striking result is that a minimization of the thermal resistivity of the device does not always lead to a reduced thermal crosstalk. We demonstrate that an additional heat barrier close to the active region and/or an improved heat transfer between the submount and the heat sink may reduce the relative thermal crosstalk, a result completely unexpected from intuitive considerations. Model calculations showed that the device yield can be increased by 20 percent improving the heat transfer between the submount and the heat sink.

This paper summarizes the results of theoretical and experimental investigations concerning the designing and fabrication of submicron nonuniform Bragg gratings with phase shifts on semiconductors, which were obtained in the Laser Research Center of Russian Academy of Sciences during the last two years. The applicability of phase-shifted gratings for wavelength-selective filtering and channel separation in high-bit-rate optical fiber networks is discussed.

Thin bismuth films were deposited by pulsed laser deposition technique. The conductivity of films was measured in-situ during deposition process. Quantum oscillations of conductivity were observed. Films were investigated by photoelectron spectroscopy technique. Red shift of outer work function for about 1.5 eV for thin films was observed.

Synthesis of bundles of single-wall carbon nanotubes in the laser ablation process was studied under different laser irradiation conditions. Surprisingly high nanotube net yields was found when the laser operated near the threshold of the free-running generation regime.

The results confirming the important role of the laser- induced vapor-phase oxidation on formation of the instability of action track and of the self-organizing structures are presented.

In the paper a review of the present state of the application of laser technology in diamond films processing is presented. Possibilities of laser stimulation of nucleation process on substrate surface for growth of continuous diamond films and laser deposition of diamond films are discussed. Application of laser radiation for diamond and diamond-like films processing and modification of physical and optical properties of diamond films by laser treatment are analyzed. The first results of diamond films preparation and characterization are presented.

High efficiency of material usage accompanied with reliable droplets filtering is demonstrated in the cross-beam pulsed laser deposition of nm-period metallic multilayers. The mean and maximum kinetic energies of ions in CBLD have proved to be 2-3 times lower as compared to the conventional PLD. Ballistic simulations of the resulting transition layer thickness in nm-period metallic multilayers are presented.

Researchers of damage formation in processes in glass are directed on studying the interaction mechanisms of powerful impulses of penetrating laser radiation with materials for the purpose of improvement of optical components resistance. However, the processes of glass structure defects formation as local areas with low factor of visible light admittance can find application in a final glassware processing. Application of treatment modes, using these effects, allows: to increase art expression of decorative glassware for furnish of buildings interior; to solve some problems of manufacturing counter devices, and also indication devices of electronic instruments. Mathematical models of defect formation processes in optically transparent materials under an action of powerful pulses of laser radiation are necessary for development of control principles of glass treatment.

Measurements of optical absorption of high-purity silica glasses made by sol-gel technology and subjected to gamma ray irradiation were held. Two different forms of nonbridging oxygen hole centers were deconvoluted. Similar results for fibers made from sol-gel silica glass have been obtained using a developed experimental set up on the basis of picosecond solid state laser. Such fibers were used to measure radiation dose from the spread sources.

The new fabrication technique of silicon dioxide Er- and Al- co-doped films is reported. Silicon dioxide film is doped from proper metal (beta) -diketonates during this chemical vapor deposition. The film photoluminescence decay process was measured as a function of deposition conditions and (Al)/(Er) ratio. The achieved photoluminescence lifetime lends support to the validity of proposed technique which can be used for preparation of active media for planar optical waveguide amplifiers.

The paper deals with the study of laser-induced rising of defects onto the surface and W surface destruction. The non- thermal glow from the back, relative to the acting laser pulses, side of the sample was registered. The glow may be caused by defects rising onto the surface under considerable thermo elastic stresses in the laser effect ares.

The method of probe beam scattering was used to study the peculiarities of monocrystalline Si surface destruction under pulsed laser irradiation. The shape of scattering signal showed that in the exposure region a surface layer rich in defects is formed. A study has been made on its influence on dynamics of sample surface deformation.

The possibility of remote detection of ultrasonic waves by measuring the IR radiation from a surface, has been shown experimentally. This effect is based on the adiabatic propagation of the surface waves. Rayleigh waves were excited by a pulsed Nd:YAG laser on the surface of a steel sample at temperatures close to 1000 degrees C. The surface temperature was estimated independently by the direct measurement of the surface vibration using a laser heterodyne interferometer. Good correlation of the time-of- flight data of the Rayleigh wave propagation, as well as in evaluated and measured temperature deviation was observed. The possibility of application of this laser ultrasonic technique of material properties evaluation at elevated temperatures is discussed.

Condition of surface plasmon wave excitation depends on dielectric permitivity of a transitive layer bordering on the metal film in which they are excited. Using this property, a family of devices is offered allowing to operate light with the help of light. Namely, it is a modulator of light controlled by light without external electronic devices, a deflector of light controlled by light and a converter of light of one wavelength of radiation to light of another wavelength.

Various kinds of nanoprobes for scanning near-field optical microscopy with the requirements and peculiarities of fabrication are discussed. A set up for fabrication of fiber made tips is presented and new ideas of optical superresolution technique for SNOM subwavelength apertures recognition is suggested.

Passive ring laser resonator of square size with a side 3.1 m is created in Sternberg State Astronomical Institute for the determination of the Earth angular rate. This work deals with the construction of resonator and mode-matching system, estimation of the resonator parameters, influence of the temperature variations on the mode structure, control of the resonator perimeter, influence of the nonplanarity and light polarization on the quality factor and, thus, on the accuracy of the Earth rotation measurements.

The drop break-up phenomenon in cases where liquid drips impinge on a rotating surface is very complicated and needs more attention. In this study, drop break-up phenomena have been investigate by measuring the residual drop sizes around the rotating cylinder. The results obtained provide useful information to understand multiphase flow in the bearing chambers of aero-engines.

The paper deals with prospects for using the cosmic lasers in remote measurements of various Near-Earth Objects parameters having dimensions above 500 m, velocity above 20 km/s, etc. The laser power calculations were made for the asteroid parameters measuring in the cosmic space.

An accurate drop size and velocity information in multiphase flows is a common requirement in many parts of the industry. This information can only be achieved if the measurements are made without distorting the flow. Laser techniques are employed for this purpose. This paper highlights the problems in using these techniques and discusses the results obtained from three different experimental rigs. It has been shown that the drop size and velocity data obtained from this study provides useful information to understand the complicated flow phenomena occurring within these flow channels. Laser results obtained from different techniques have also been analyzed for identical flow conditions.

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.

The technical characteristics, advantages and applications of an automated optoelectronic measuring system designed by 'Optel' company, State Aviation University of Ufa, are presented in this paper. The measuring apparatus can be applied for industrial development and research, for example, in rapid prototyping, and for obtaining geometrical parameters in medicine and criminalistics. It essentially is a non-contact and rapid scanning system, allowing measurements of complex shaped objects like metal and plastic workpieces or parts of human body.

Recurrence method of interferometric data processing was developed and investigated. The method proposed is based on theory of stochastic difference equations. Recurrence filtering of measured surface profile data provides the result definition in a wide range of profile deviation with moderate requirement to a priori estimates of interferometric process parameters. There were found the accuracy estimates of real interference signal parameters in a two-wavelength interferometer with phase recovering in real time scale of data obtaining.

The open resonators (ORs): the spherical OR with spherical body in its center and the two-mirror semispherical OR with plane parallel body are considered. The expressions of spectrum and Q-factor calculations are derived. The examples are presented of experimental application of such ORs for solid state diagnosis.

The experimental set-up for measuring and control of laser amplifier parameters in real time is described. The obtained experimental data are presented to illustrate the set-up operation.

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.

Different control methods of phase delay in the nematic liquid crystal layer are analyzed. The experimental optimization results of dual-frequency control voltage parameters are discussed and the adaptive system for hunting of these parameters is represented.

A new type of phase liquid crystal modulators with distributed electrical parameters is proposed. These modulators make it feasible to use minimal number of electrodes to from a desirable phase shape. We devised methods of control and investigated the modal liquid crystal cylindrical and spherical lenses, and the multi-element wavefront corrector with controlled influence as well. The focusing by means of the adaptive lenses is presented. We demonstrate two approaches in optimal control. The first consists in computing the optimal control voltage through liquid crystal and lens parameters. The second consists in feedback use.

We represent here our report on the remote study of the Martian atmosphere near the surface by a compact aerosol diode lidar during the Mars Surveyor Lander-98 mission. We are planning to study the daily and seasonal variations of the vertical structure of the atmosphere near the surface, both in active and passive mode. In passive mode, the lidar will measure: (1) sky brightness by basic receiving channel; (2) sky brightness in polarization lane of additional receiving channel. In active mode, the lidar measures the vertical profile of the atmospheric backscatter coefficient.

Self-consistent theoretical model and computer code for the simulation of the control of atmospheric transmission by means of high-power IR lasers are presented. High-resolution nonequilibrium absorption spectra of the atmosphere are simulated and analyzed. The results of calculations are presented illustrating a number of effects accompanying propagation of intense IR radiation in the atmosphere: negative absorption caused by the inversion of CO₂ and H₂O levels populations: laser-induced absorption; laser- induced shift of transmission microwindows; explosive-like absorption. The indicated phenomena may for a basis for new methods of remote sensing of the atmosphere.

The global cosmic systems may be used for solution of problems of the Earth supply with energy in the nearest future. Such system can involve several cosmic platforms on the polar or heliostationary orbits. The present paper deals with prospects for using 3 types of the high power IR lasers for the cosmic power systems. The first laser type is a laser optically pumped by thermal radiation; it uses an intermediate 'black body' radiator heated by solar radiation and offers substantial and important advantages. The second laser type is a CO₂ laser with radio frequency pumping. We can use several 33 X 30000 W lasers in one module for approximately 1 MW cosmic laser system. The module of 320 X 320 m² solar cells is needed for such laser system energy supply. The third laser type is a CO₂ gas-dynamic laser. The numerical studies of carbon dioxide laser that is pumped by solar-thermal heating were made, and the output laser power approximately 1 MW was calculated. The parameters studies were conducted for this laser conception.

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.