The paper discusses the industry and perspective technologies for isotope production and makes their comparative analysis. Special attention is paid to the laser methods of isotope separation. The main fields of isotope application are reviewed. The paper describes the contribution of the experts of the Russian Research Center, Kurchatov Institute, into the development of isotope technologies. Isotope production and application are shown to have a good perspective.

VUV-UV multiwavelength excitation process for precision microfabrication of hard materials, in which simultaneous irradiation of the vacuum ultraviolet (VUV) laser beam with extremely small laser fluence and the ultraviolet (UV) laser beam leads to effective ablation, is reviewed. A collinear irradiation system of F₂ and KrF excimer lasers has been developed for this process. This system achieves well- defined micropatterning of fused silica and GaN with little thermal influence and little debris deposition. Ablation mechanism is explained as absorption of KrF excimer laser by excited-states formed by F₂ laser (excited-state absorption: ESA). In addition, this technique is applied for much more efficient refractive index modification of fused silica compared with single F₂ laser irradiation, which is attributed to resonance photoionization-like process based on ESA. These processes are characterized by experiments carried out at various conditions such as laser fluence, irradiation timing of each laser beam, and pulse number.

In this work we present the results of experimental investigations of laser ablation initiated by 200 fs and 30 ps laser pulses with the energy fluence of ~0.2 J/cm². It was shown that in the case of picosecond pulses the ablation depth is governed by the thermal conductivity whereas in the case of femtosecond pulses the skin-layer depth is the major parameter. We also obtained that the duration and the energy fluence of laser pulse strongly affects spatial distribution of stoichiometric composition of sputtered material.

We review applications of photopolymerization and photodamage by tightly focused picosecond and femtosecond pulses for the formation of three-dimensional structures. Laser microfabrication of various structures, like surface gratings, 3D optical memory, 2D and 3D photonic crystals, 3D microfluidic systems, etc., are described. Microfabrication by laser irradiation provides new opportunities to realize microstructures and microdevices, highly demanded in a number of fields, e.g., microchemistry, information storage, and photonics. The background of this technique is very simple, and relies on modification of materials by intense, strongly focused laser irradiation. In this highly spatially localized region, the material may become destroyed, solidified from liquid, or otherwise photomodified, and complex structures can be formed from many photomodified regions. Below, we describe techniques, applications, and achievements of laser microstructuring in liquid resins and solid silica glasses.

The optical forming of the waveguide from low absorbing photopolymerizing composition upon self-channeling of light leaving fibers is numerically and experimentally investigated. The waveguiding channel is shown to be formed practically at any mode structure of initial radiation. The lengthening of 50 micrometers fiber was experimentally confirmed.

The time-of-flight probe method was used in investigations of erosion plume in ablation of copper with 308 nm radiation of excimer XeCl laser in vacuum. The time-of-flight curves of electron and ion currents at the probe were obtained in the range from 0.2 to 2.2 J/cm^-2 of energy densities at the target with probe-to-target separations from 10 to 133 mm. Multimodal distributions of ions by scatter velocities have been revealed. The voltage-current curves of probe current have been constructed in the range of probe potentials +/- 18 V. The electron temperature has been calculated for different plume regions. It has been revealed that the plume electron temperature is nonuniform.

The erosion plume resulting from an ablation of tantalum target in vacuum with excimer laser radiation (308 nm) was studied using Langmuir probe. The spatial and temporal dependencies of electron probe currents were obtained in real time. The electron temperature of different plume regions was determined from a series of I-U characteristics taken at different distances between probe and target. It was established that the plume electron temperature is nonuniform and has a maximum value in front of the plume. The acceleration of ions on plume irradiation with CW CO₂ laser recorded. The increase in ions energy from 25 to 50 eV was observed.

On irradiation of metallic targets from niobium and tantalum with excimer XeCl laser (308 nm) the spectra of erosion plume were obtained. These spectra were used in studying the plume qualitative composition. The velocities of atom and ion scatter were measured by the time-of-flight method. Plasma electron temperature was found by continuous spectrum of plume radiation. The results obtained were compared with the outcomes of the previously performed probe measurements of electron temperature and ion scatter velocities.

The paper deals with analytical investigation of technological equipment tolerance requirements for multiplayer optical waveguides structure creation in monolithic glass substrate by laser-induced clearing of (gamma) -induced color centers. It is proved that autocorrelation interval of waveguide boundary deviation is equal to the step of moving mechanism and is considerably more than signal wavelength. Thus the main scattering mechanism is the axis deviation and the local size varying. We propose the new waveguide creation method in single run of optical system by mean of two laser sources. It allows to reduce the scattering on the local size varying. Theoretical estimation of such waveguide scattering losses is 0.1 dB/cm when the step (tolerance) of laser beam moving is 0.1 micrometers .

The purpose of researches is the establishment of optimum regimes for laser cutting of fiber glasses, fiber glass fabrics and materials on their basis, for thermal strengthening of knives of shredding machines, cast iron foundry forms for manufacture of empties and formulation of the requirements to the equipment.

Gas assisted laser cutting (GALC) is accompanied by formation of heat affected zone (HAZ). A part of laser beam power is spent on this. Thermal losses cannot only decrease GALC efficiency, but cause thermal deformations of the treated material. The temperature measurement of samples heating under GALC were performed. The dependence of the samples temperature on cutting velocity was obtained under blowing by nitrogen and oxygen. In the first case dross was formed, the contribution of its crystallization enthalpy into plate heating was taken into account in estimations of GALC energy balance. As a result, the limiting physical value of heat losses was obtained, and its dependence on velocity was plotted. It has been revealed that a portion of thermal losses at low cutting velocities was essential. A qualitative physical model was suggested which gave a satisfactory description of the obtained experimental results. The GALC conditions for minimum thermal losses were defined.

Particularities of using CW and pulsed-periodic laser radiation for cutting sheet carbon-carbon composites material and carbon fabric were studied. The processes of shaping the channel of evaporation, ways of reduction of zone of thermal influence and increasing of quality under laser cutting carbon-carbon composites were considered. Structure and phase composition of carbon in zone of thermal influence were explored. It is shown that use of pulsed- periodic laser radiation for cutting carbon composites material allows to greatly reduce or practically completely exclude the zone of thermal influence and perfect the quality of cutting. Laser cutting is one of the most perspective ways of dimensional processing of carbon-carbon composites.

Many users of laser technological processes are trying to create data bases accumulating their experience in laser processing of materials. The data bases are useful tools to render help to technicians working with laser machines. But it is only the first step in utilization of intelligent computer programs. In this paper we present the results of the development of expert system (ES) to help technicians in the choice of best conditions for laser processing of materials. The ES has been created on the basis of practical knowledge of experts and experimental results collected to the data base. The set of parameters was developed for the description of laser technological processes. Each of the processes was characterized by the values of such parameters changing in some reasonable diapasons. Those parameters were divided into input and output groups. The input group of parameters included the main technical characteristics of the laser, the type of the material and the demands on the quality of laser processing products. The output group of parameters consisted of the set of laser processing conditions recommended by the expert system. Generally, the ES presents a computer model of the expert's decision making process. The steps of such a process are a new task analysis, search of closest past cases, evaluation of tasks similarity and so on. The expert system called MALS (Machine Learning Shell) is presented in this paper as an example of ES which could give consultations on the best choice of the laser cutting process.

A physical model of formation of stratified structures of components in a stiffening melt after the action of a penetrating laser beam on the heterogeneous system is considered. The model explains the formation of layers by centrifugal running or tightening of microparticles in size about 10^-4 - 10^-2 cm of an impurity (either heavier or easier in relation to the basic material). This centrifugal effect should be shown in vortex melt flows, with speeds in the range of several cm/s, generated by hydrodynamic instabilities of the certain nature. In the case of continuous scanning of a CW beam along the surface of a material, there can be generated non-stationary regular three-dimensional vortex melt flows explained by injection of flooded melt jets from a front wall keyhole (KH). After solidification of the heterogeneous melt, behind of traveling KH the strip-looking layers of an insoluble impurity are observed in the direction of beam scanning velocity. Our experimental data do not contradict to this model. In the case of cylindrical-symmetric layer melt, surrounding the KH in the absence of scanning of the laser beam, the vortex flows rise due to capillary collapse of the KH. After deenergizing the laser and solidification of the melt, periodic layers of the insoluble impurity are fixed which look like curved disks located transverse to the keyhole axis.

The welding technology by simultaneous radiation of two Nd:YAG lasers is suggested. The comparative experiment results are given. This laser welding technology allows to decrease the porosity of welding stitch 2-2.5 times and at the same time increase the depth of the welding canal 1.5-2 times in comparison with traditional methods of laser welding.

The contribution deals with the diagnostics of laser induced plasma (LIP) by optical emission spectroscopy. Laser induced plasma occurs during laser welding and reveals important information about technological process. The performed experiments were concerned with in-time spectral analysis (wavelength range: 200-800 nm) of laser induced plasma of austenitic steel (18% Cr, 9% Ni) during cw CO₂ laser welding. Circumstances of conversion from conducting mode to keyhole mode (and vice versa) were investigated. A comparison of the characteristics of the spectrum emission, penetration characteristics and input welding parameters was also studied.

Static and fatigue strengths of laser welded overlap joints with controlled and full penetrations of 3 mm AISI 304 were investigated. The depth of penetration was controlled by employing certain combinations of laser power and travel speed. Experimental program showed that fatigue and static strengths are dependent on the weld width and independent of the depth of penetration. Larger weld width is attributed to higher static and fatigue strengths. The joints with full penetration possess the same strength characteristics as the samples with controlled penetration.

Characteristic modification of polymer surface using laser radiation is an attractive alternative to chemical processing. In recent years, many researches using laser to modify the surface of high polymer fibers or films have been done. In this article, several different methods are discussed. On hand of a series of experiments the properties and mechanisms of these technologies are compared. Effects of wavelength of lasers on poly (ethylene terephthalate) (PET) textiles are studied. Finally, the merits and drawbacks of laser processes in comparison with other competing techniques such as plasma processing are commented.

The paper presents the results of technology development for laser modification (hardening, alloying) of stamping tool surfaces in production of automobile parts. The techniques of laser treatment have been selected and developed, which make use of high-power industrial CO₂ lasers MTL-2.5 and TL-5 with 2.0 to 5.0 kW power and the special-purpose five- coordinate manipulator of VISP-125A type. Metallographic studies of stamp samples have been conducted following laser hardening and alloying. The testing of the processed samples on test panel of the Metal Forming Institute gave positive results. The data obtained served as the basis for development of specific technologies for laser hardening and allowing of stamping tool for purposes of automobile industry.

The researches and data processing of laser pulse interaction with the surface of the target of aluminum alloy versus the air pressure and pulse power were carried out. The alloy 1420 is composed of 92% Al, 6% Mg and 2% Li. The industrial laser with pulse-half width of 3 ms was used to achieve the power density up to 2 x 10⁶ W/cm².

It was shown that laser pulse treatment assures significant advantages of the hardened hard alloy tungsten-cobalt tools operating in the conditions of the adhesion-fatigue wear. The average cutting temperature at turning of steel was found experimentally to be decreased due to laser treatment. It was shown that stability of the cutting characteristics of hardened tools was twice as more with optimal laser treatment. The interconnection between observed increasing of wear resistance of hardened tools and structure-phase changes in the laser treatment zone was determined.

Experimental investigations of getting protective high temperature coatings on carbon-carbon composites by means of laser cladding were accomplished. The reactionary formation of coatings was investigated during laser melting of powders Si - C and Si - Mo. It was stated that the high quality of coatings is provided by the presence of free silicon. The adhesion strength of siliceous coatings with carbon materials exceeds the shear strength of the carbon-carbon composites. The optimum parameters of processing, structures and thicknesses of protective layers were determined. The microstructure of laser coatings were investigated by means of metallographic microscopy and by a method of the x-ray phase analysis.

In the paper the peculiarities of relief inhomogeneities formation on silicon surface were investigated at irradiation by submicrosecond laser pulses in various gases. It was shown that the development and relaxation time of these inhomogeneities poorly depends on a type of gas.

The paper presents the results of study of thin plates and films mechanoluminescence initiated by thermal deformations resulting from high-power laser pulse action. The dependence of excitation threshold and intensity of mechanoluminescence on plates thickness and the dependence of intensity of mechanoluminescence on laser pulse power density were investigated.

For the diagnostics of processes induced by laser radiation we developed the system on basis of copper laser. This system (laser monitor) consists of laser brightness amplifier, CCD-camera, computer, and allows to obtain the image of a processing surface through plasma plume in a real time. In contradistinction to classical schemes of laser processing our system realizes continuous visual control of processing surface directly in the process of laser radiation interaction with material. The computer analysis of obtained information allows to form control signals for the laser technological complex. The offered system provides the increasing of reliability and accuracy of carrying out measurements and can be used in various technological processes of treatment of metal. In this report we present the result of processing the optical images of dynamic processes on substance surface by fractal geometry methods.

The characteristics of turbulent flow of laser mixture in high-power industrial CO₂ lasers with fast axial flow have an influence on energy parameters of laser beam. In particular the transverse size of DC discharge and discharge stability depend on coefficient of turbulent diffusion. Moreover, turbulent pulsations cause small-scale optical inhomogeneities in the active medium. By the method of intra-resonator four-wave mixing in the active mixture of industrial CO₂ laser with fast axial flow the coefficient of turbulent diffusion was determined. The nonlinearity of gain coefficient was used, and dissipation of amplitude diffraction grating due to turbulent diffusion was taken into consideration.

This paper presents in vitro the measuring techniques and experimental results of optical parameters of human lung tissue. Optical properties of biotissue are briefly described in the introduction. A new approach to measure optical parameters has been developed. This indirect approach combines the solution of the diffusion theory with a result of Monte Carlo simulation to calculate the optical parameters of normal and carcinomatous human lung tissues in vitro at the wavelengths of 406.7-415.4 nm, 632.8 nm and 676.4 nm, respectively. We obtained the effective attenuation coefficients (mu) _eff and the optical penetration depths (delta) of fresh lung tissue at above violet and red wavelengths, and it is a great help to understand better the optical characteristics of lung tissue in clinical light dosimetry.

The processes of laser burning and ignition on the surface of refractory metal (such as Zr, Ni, Hf) are researched in this paper. The regime of gas phase limit, at which the metal heating leads to the high temperature fusion of nitrogen compounds on their surface under condition P_limit. P has been performed, and it leads only to the creation of oxide compounds at P_limit. < P. It is shown that nitrogen creation has been a sharp appearance of new phase in the target heating dynamics. It is possible that its diagnostic as a non-stable metal burning product in the air could be done by optical method registration of non- monotonous changing of reflect capability R of the foliated system 'metal - oxide'.

Optimum spectral regions are selected for absorption diagnostics of 38 organic and inorganic atmospheric pollutants in the range of 2.5-4.2 micrometers . Computer code ANLINES is developed and numerical simulation of multicomponent spectra is made. Sounding frequencies for diagnostics of 7 inorganic gases with using first-overtone CO laser and HF/DF lasers are selected. Different parameters of sensitivity and selectivity are discussed: minimum detectable concentrations, partial sensitivities, partial selectivities, cross sensitivities. The comparison of these parameters is made for first-overtone CO and HF/DF lasers.

The mechanism of channel punching in the heart muscle (myocardium) by a pulse of high-power CO₂ laser was studied. Water, PMMA and biotissue of animals were used as the models. Diagnostics of the punching process was performed by the methods of registration of sound vibrations in the air and back scattering of laser radiation. It has been revealed that at channel punching in various media, sound vibrations are excited in the spectrum region from 1 to 3.5 kHz, which are due to turbulent pulsation of vapor- drop flow ejected from the channel. The spectrum of acoustic vibrations depends on positions of the channel bottom and is sensitive to the boundary between the myocardial tissue and blood. The measurement of sound vibrations spectra can serve as the basis for diagnostics of the process of channel punching in myocardium.

The paper gives a description of the phenomenon that has a considerable, and often a decisive, influence on the course of physical processes under laser radiation interaction with a substance having at least one liquid phase. The explanation of the essence of this phenomenon lies at the intersection of two branches of science: mechanics of liquids and gases, and physical chemistry (thermodynamics of heterogeneous systems). Capillary thermo-concentration instability (CTCI) is present at any non-isotropic input of energy to a heterogeneous thermodynamical system having several phases. This instability manifests itself at the phase boundary and causes processes of mass transfer, redistribution of components, emergence of new phases, relaxation vibrations. This phenomenon is most pronounced in local processes at interaction of laser radiation with matter. The theory and practice of this phenomenon unite and describe a new class of effects widely spread in nature, which play a decisive role in many physical and chemical processes and find even more various spheres of practical application. A number of examples of capillary thermo- concentration instability application are given: separation of liquid mixtures to components under thermal action of laser beam; a new method of thermal silver-free photography; control of liquid metal convection in laser alloying.

The aim of the current work is to investigate morphology, structure and element composition of the condensate of moon ground deposited under pulse laser influence which simulated meteoric bombardment. It has been shown that the morphology of the condensate is similar to real morphology of moon regolith. The condensate composition was found to be highly different from the target composition.

Application of the achievements of the ISTC projects is one of the main problems being solved to achieve one of the basic goals of the ISTC, namely, to adapt Russian scientists to conditions of developing market economy in Russia. The present report is aimed at rendering of promotional services for ISTC project teams in the context of the program of projects outcomes valorization.

Destructive action of laser radiation to nucleic acids doped by cation dyes is investigated. The absorption by the bounded dyes of laser radiation initiates various transformations of polymeric chains - cutting of a double helix on fragments and local thermal denaturation. The molecular mechanisms of dye-macromolecule complex destruction are discussed.

In this paper the effect of optical feedback on two- frequency mode characteristics of He-Ne laser is discussed. The influences of back-reflections on the parameter of the two-frequency mode characteristics of He-Ne laser are estimated.

Two-dimensional cylindrically symmetric mathematical model of heating, melting and evaporation of solid matter by laser radiation with obvious representation of trailing boundary of absorption - evaporation and with self-coordinated energy balance in a zone of laser influence is submitted.

The development of industrial lasers (CO₂ lasers, solid- state, excimer and semiconductor lasers) and industrial applications (heat treatment, welding, cutting, marking, engraving, etc.) in China are reported in this paper. The research institutes in China, engaged in these areas, are presented. In recent years, the industry of optoelectronics in China has rapidly grown; the national optoelectronics and information industry base in Wuhan is introduced as well.

In order to develop electroluminescent and laser devices based on the ultraviolet exciton emission of ZnO, it will be important to fabricate good p-n junctions. As-grown ZnO is normally of n-type because of oxygen vacancies and zinc interstitials acting as donors. Making p-type ZnO has been more difficult, believed due to self-compensation by intrinsic defects such as the donors V_o and Zn_i, or possibly by hydrogen as an unintentional extrinsic donor. In this work, we demonstrate that reactively sputtered, vacuum- annealed ZnO films can be changed from n-type to moderate p- type by adjusting the oxygen/argon ratio in the sputtering plasma. We report the properties of p-n homojunctions fabricated in this way and characterize transport in the films by Hall measurements. Ohmic contacts were formed by deposition of Au/Al. Our finding of p-type conductivity in apparently intrinsic ZnO formed by reactive sputtering is not inconsistent with calculated defect formation enthalpies if account is taken of the higher chemical potential of the atomic (ionic) oxygen reservoir represented by the sputter plasma, compared to the molecular oxygen reservoir assumed in the calculation of formation enthalpies. Photoluminescence of the sputtered and annealed films is characterized mainly by the 3.27 eV exciton peak at room temperature.

A survey of experimental and theoretical results on physics of a CO laser operating on first-overtone (FO) vibrational transitions V plus 2 implies V is presented. A special attention is paid to quite new results recently obtained at the P. N. Lebedev Physics Institute (Russia), TRINITI (Russia) and Air Force Research Lab. (USA). Efficient multiwavelength pulsed FO CO lasing with output efficiency up to 11% and specific output energy up to 50 J/l Amagat is observed within the spectral range of 2.5-4.1 micrometers corresponding to the vibrational transitions V plus 2 implies V from 6 implies 4 up to 37 implies 35. Single-line frequency tunable FO CO lasing on the wavelengths from approximately 2.7 up to 4.2 micrometers with the maximum output efficiency up to approximately 1% is also observed. Multiline and single-line lasing on 430 ro-vibrational lines is obtained. Theoretical calculations based on the experimental data predict that multiline FO CO laser efficiency can be enhanced up to 20%. The effect of spectrum alternation, i.e., an alternation of strong and weak vibrational bands, in pulsed FO CO laser spectrum, which is determined by two sets of cascade transitions, is experimentally observed for the first time. An influence of nitrogen on spectral characteristics of a single-line FO CO laser operating on very high vibrational transitions up to 38 implies 36, which is related to quasi-resonance overlapping of the transition with 0 implies 1 transition of nitrogen molecule, is discussed. High efficiency and high specific output energy places the FO CO laser amongst other high-power lasers such as CO₂ laser, fundamental band CO laser and HF(DF) laser.

The power in the bucket (PIB) and (beta) -parameter are chosen as criteria for characterizing the laser beam quality in the far field, the beam quality of annular lasers with or without phase distributions is studied in detail. It is shown that the better focusability is achieved at the real focal plane, and a suitable choice of negative phase distributions may improve the beam quality.

The investigations and constructions of compact CW RF- excitation waveguide CO₂ lasers with square and slab discharge channels geometry of power scale 10divided by100 W are described. The power, beam shape and lifetime in sealed-off mode have been investigated. Those models can be recommended as basic samples for 100divided by250 W lasers.

The principle and method of high power CO₂ laser excited by switching power have been proposed. In the traditional transverse flow pin-plate CO₂ laser, a high frequency switching power was overlapped on the DC discharge to obtain uniform discharge. Experimental results show that this new excited technique can improve the discharge stability, and modulate the laser output. The new method is also profitable for minimization and industrial applications of high power transverse flow CO₂ laser.

The new discharge system for RF-excited lasers is discussed in this paper, in which symmetric, homogeneous helical glow discharge by RF excitation can be got. The theoretical model based on the discharge system has been set up. The distributions of the electrical field and electron density inside the discharge tube are calculated. The advantages of the discharge system are consistent with the experimental results well.

An opportunity to compensate phase and polarizing distortions of the laser radiation directly in Nd:GGG active medium and also in phototropic LiF:F₂^- crystal is investigated. We found that an application of modified Sagnac interferometer with passive LiF:F₂^- Q- switcher, located inside it, allows not only to increase stability and power of laser pulses, but also to narrow the laser oscillation spectrum. The possibility is demonstrated of generating single-mode radiation with an energy in a train of laser pulses higher than 7 J, a peak power of a single pulse in a train up to 50 kW, the spatial brightness exceeding 5 x 10¹⁰ W/cm² x sr, and the coherence length in excess of 13 m.

Design of autonomous mobile high power CO₂ gas dynamic laser (GDL) using regenerative heat exchangers for heating of laser mixtures optimized in composition was presented. A mobile laser is designed specially to be mounted in standard railway platforms. Various applications of mobile lasers in civil engineering were discussed. Economical aspects of exploitation of mobile CO₂ GDL were analyzed.

The dependence of the specific energy of the high-pressure CO₂ laser (4.1 and 11.1 atm) with the optical pumping on the resonator losses coefficient and density of the absorbed energy of radiation of the HF laser on transition P1(8) is studied. The maximal values of the specific (200 J/l) and the total (7 J) radiation energy of the high-pressure CO₂ laser (11.1 atm) are obtained with coefficient of transformation of the pumping radiation energy ((lambda) equals2.78 micrometers ) to energy of the CO₂ laser radiation ((lambda) equals10.6 micrometers ) being equal to approximately 19% (quantum yield approximately 73%), and with parameter of excess of the unsaturated gain (g₀equals0.1 l/cm) above the lasing threshold (g_t) m equals g₀/g_t approximately equals 4.

New regime of self-pulsing generation in the unstable resonator (UR) of the transverse flow laser was found numerically. The regime is characterized with high pulse repetition rate (Omega) _Rapproximately equals 10²/(tau) _f ((tau) _f is the time required for the medium to flow from the edge to the axis of the resonator). It can be considered as relaxation pulsing regime and can be interesting from the point of view of material laser treatment technology. Various regimes of lasing can be easily commuted over.

Self-Q-switching of the Nd:crystal (Nd:YAG, Nd:GGG) and the Nd:glass multiloop lasers (phosphorus GLS-22) with self- pumped phase conjugation (SPC) in active media is investigated experimentally and theoretically. A possibility to realize single-mode single-frequent self-Q-switched laser radiation as repetitive giant pulse trains of 50 W average and 100 kW peak power with no Q-switcher is shown. Temporal dynamics of self-Q-switching and the mechanism of its occurrence on gain gratings are investigated with a help of the rate equations.

Parameters of CdSSe and GaAs electron-beam-pumped laser arrays with optically coupled elements were studied. A transversal geometry of pumping was applied. A special configuration of active element provided the optical coupling of array cells. Pulsed electron gun of 300 keV energy and 1 ns electron beam pulse duration was used. An abrupt rising of output laser power and decrease in the threshold current density were obtained with the increase in the number of coupled elements. The parameters of laser array were computed. The correspondence of theoretical and experimental results was observed.

Numerical code for simulating the vibrational distribution function in an RF excited slab CO laser with diffusion cooling is developed. Spatial distributions of the small signal gain on the fundamental and first overtone for different vibration-rotation transitions were obtained. Dependence of gain on the wall temperature, input power and gas mixtures was studied.

By introducing a transfer matrix with an explicit frequency variability for a phase-conjugate mirror (PCM), the Gaussian mode and its stability condition were derived in phase- conjugate resonator (PCR) bounded by one or two PCMs formed by a nondegenerate four-wave mixing. The Gaussian mode and its generalized self-consistency condition were derived in a stimulated scattering phase-conjugate resonator.

The innovative structure and working properties of a high- power co-axial phase change cooled unstable resonator which is cooled by solid-liquid phase transition material are reported in this paper. The experimental result shows it is a useful resonator to be used in high-power lasers.

A new type of aerodynamic window structure using jet- injection is developed. The theoretical analysis and experimental research are presented as well. Results showed that while the lowest sealing pressure is 5.0 Torr and gas consumption is 35 g/s, the ratio of the Strehl reaches 0.98. The new aerodynamic window is demonstrated satisfactorily in the experiment connected to high-power laser.

The concept of construction of multifunctional lasers- robots, which are carrying out the wide nomenclature of the basic and auxiliary technological operations of laser processing, is offered. Manipulator systems of lasers-robots are considered as objects of control.

The paper presents the structure and the description of the laser-robot, constructed on the basis of the serial transport robot and kinematics of the independent manipulator, connected to it by independent manipulator of optics. The distributed adaptive control system provides work of the robot in conditions of uncertainty and unstationarity of objects of processing, force-and-moment unloading, cooling of rejecting mirrors and submission of gases in a zone of processing.

The outcomes of researches of the operation of the active element of the nitrogen laser pumped from an inductive energy store with a thyratron as a disconnector of the current are shown. Two methods of the arrangement of a discharge tube are considered: outside of accumulative inductance and inside it. The characteristics of the operation of the current disconnector are given.

The technical decision of the wide-aperture multichannel solid-state amplifier is offered, which coherent beam in transversal section is 94% filled by laser radiation, that provides minimum diffractional losses at beam focusing at large distances. The beam divergence close to diffractional is provided by adaptive mirrors, used in a system, and phasing system of the amplifier channels. The amplifier can be used in extreme situations, for example, for cutting from large distance 'under the radical' metal armature of burning oil and gas slits and also for scientific researches in the field of laser thermonuclear synthesis.

The polycrystalline optical IR fibers based on silver halogenides AgCl-AgBr exhibiting low losses (0.5 dB/m and less) in the wavelength range from 4.0 to 16.0 micrometers are of interest in technical and medico-biological applications as fiber optic sensing devices and flexible systems for delivery of low-power CO₂ and CO lasers radiation.

Within the frame of a fluid drift-diffusion model the possibility of a current instability growth in elevated gas discharge was numerically investigated. Under physically reasonable assumptions about the values of characteristic electron energy and secondary emission coefficient, we observed the growth of perturbations and formation of a periodic in space current structure. However, competition between the current stripes has a substantial effect on their evolution, leading to suppressing of the neighboring current stripes. Further inspection of numerical solution discloses that the instabilities growth begins in anode region, but the net result essentially depends on the processes in cathode region. The cathode spots are markedly less in size than the anode spots, and their current densities differ widely. To account for several phenomenological aspects of formation of constricted discharge structures and cooperative interplay thereof, a simple one-dimensional physical model is proposed. It should be noted that a development of the current structures of the abnormal glow exhibits a nonthreshold nature and owes its origin to the purely electrodynamical phenomenon long before the emergence of the bulk thermal, plasma chemistry, and nonlinear surface effects.

A novel design for optically addressed modal liquid-crystal adaptive lens is presented. Described is the implementation of the 2-layer lens, a simplified model explaining its performance, and first experimental results on wave front shaping and focusing by the optically addressed lens.

Artificial laser guide star (LGS) is usually created by excitation of sodium atoms in the natural layer at 90 km with a yellow laser beam at 589.2 nm. Such a spot-like source is used for guiding the adaptive optics system of telescopes, that allows to improve greatly the quality of images of real astronomic objects by correcting the wavefront distortions induced by atmospheric turbulence. In frames of ALFA project a single-frequency yellow source of 3-4 W output power has been developed and is already used for LGS excitation. In this paper we report on the pump laser for dye amplifier developed for the Max Planck Institute of Extraterrestrial Physics in Garching, Germany, that will be applied for substantial enhancement of the output power in the system. The developed argon laser provides high angular stability and beam quality by means of active cavity alignment at 70 W output level, that has no analogues. Basic principles and device design are described.

The optical analyzing method of blood micro-circulation and another dynamical characteristics of biological objects based on using the low-frequency processing of scattering laser wave is represented. The main idea of the method proposed is the combination of adaptive virtual optical filter as a lateral diaphragm of laser speckles, formed by scattering of laser wave in a biological tissue, and a multi-segment photoreceiver in the plane of analysis. The method of speckle-interferometry allows to develop the system of express-measuring and control of the local dynamical parameters of biological objects with the sensitivity more than it is in a traditional Doppler analysis scheme.

When an adaptive optical system is applied for laser beam control it is very important to know the beam parameters such as beam width, divergence angle, beam quality factor M², etc., before and after correction. That is why the sensor making such estimations should be included in any laser adaptive optical system. This paper describes the sensor design, possibilities, the principle of measurements, and its place in the whole adaptive optical system.

In the recent past years, developments in the rapid prototyping of various parts have taken new dynamic turns in manufacturing technology. Besides the use of new materials, unrelenting demands for the downsizing of miniature components in the micro-domain have expanded the application area of the rapid prototype product. Their requirements with reduced time lag have forced the manufacturers to adopt and develop innovative techniques which meet these demands. In order to overcome this problem, several techniques, predominantly laser stereolithography, have successfully been used in Japan for the past several years to generate a complex micro-/macro part of polymer resin based in two- or three-dimensional domains. The main disadvantage of this process is that they consist of two or more steps for producing metallic/metal-matrix composite microstructures. But recently developed new technologies of selective laser sintering/generating and ballistic particles manufacturing processes offer the possibility of the direct generation of these microstructures in a single step process. The last two processes actually have limitations on the feature size produced, due to the minimum size of the molten droplet. But the selective laser sintering technique can bind the particles by melting together at the interfacial grain contact area only and thus producing smaller feature sizes. Based upon these techniques, the present paper aims to review the current status and the future prospective of laser assisted rapid prototyping in Japan.

A diverse range of Rapid Prototyping, or layer manufacturing techniques have evolved since the introduction of the first process in the late 1980s. Many, although not all, rapid prototyping processes rely on lasers to provide a localised and controllable source of light for curing a liquid photopolymer or heat to fuse thermoplastic powders to form objects. This paper will provide an overview of laser based rapid prototyping methods and discuss the future direction of this technology in light of the threats posed by low cost 3D printing techniques and the opportunity for the direct manufacture of metal components.

An important stage of rapid prototyping technology is generating computer 3D model of an object to be reproduced. Wide variety of techniques for 3D model generation exists beginning with manual 3D models generation and finishing with full-automated reverse engineering system. The progress in CCD sensors and computers provides the background for integration of photogrammetry as an accurate 3D data source with CAD/CAM. The paper presents the results of developing photogrammetric methods for non-contact spatial coordinates measurements and generation of computer 3D model of real objects. The technology is based on object convergent images processing for calculating its 3D coordinates and surface reconstruction. The hardware used for spatial coordinates measurements is based on PC as central processing unit and video camera as image acquisition device. The original software for Windows 9X realizes the complete technology of 3D reconstruction for rapid input of geometry data in CAD/CAM systems. Technical characteristics of developed systems are given along with the results of applying for various tasks of 3D reconstruction. The paper describes the techniques used for non-contact measurements and the methods providing metric characteristics of reconstructed 3D model. Also the results of system application for 3D reconstruction of complex industrial objects are presented.

In today's market place the potential of Reverse Engineering as a time compression tool is commonly lost under its traditional definition. The term Reverse Engineering was coined way back at the advent of CMM machines and 3D CAD systems to describe the process of fitting surfaces to captured point data. Since these early beginnings, downstream hardware scanning and digitising systems have evolved in parallel with an upstream demand, greatly increasing the potential of a point cloud data set within engineering design and manufacturing processes. The paper will discuss the issues surrounding Reverse Engineering at the turn of the millennium.

The existing technology of models production from sheet materials - LOM - has the shortcomings which restrict its applications: small choice of materials, low accuracy of production, limitations for shape complexity, problems of waste separation. The paper offers the experimentally justified methods of obtaining models from promising materials, which do not exhibit the above-listed shortcomings. The result was attained by optimization of laser cutting algorithms and by choosing a principally new means of selective joining of layers in the process of 3D model synthesis.

In 2000-2001 the specialists of TsAGI and ILIT of the Russian Academy of Sciences developed the photopolymeric molds and tried up the technology of producing in these molds the wing tips of a complicated shape made of composite materials. During further development a complicated hybrid structure of a balance aerodynamic model was generated including primary metallic elements, contour-forming elements made of composites as well as separate contour- forming elements made directly from photopolymer. Prospects for extending this technology to dynamic and elastic models are considered.

Perspectives of laser synthesis of functional graded materials (FGM) with controlled pores and chemical mixture are discussed. Filter elements from metal-polymer powder compositions were fabricated by the selective laser sintering method. It was shown that physical properties of the composited 3D part can change from layer to layer and have no nature analogy. In particular, permeability and porosity coefficients of synthesized 3D parts were determined depending on laser influence parameters and a polymer quantity. Wide opportunities of preliminary computer modeling of the porous space structure, the forecast filtration characteristics are discussed.

In the present paper, on the basis of known earlier approaches, a continuous theoretical model was proposed, describing the behavior of viscoplastic porous powdered mixture (in general case made from some components) at high- speed laser heating, observed during SLS of a separate monolayer.

The paper presents the history of development and technological adjustment of the first Russian system for manufacturing 3D models using LOM algorithm; the experience of this system application is considered and analyzed. The principles of its arrangement, peculiarities of design and distinctions from LOM systems of Helisys type are considered. The main characteristics of the system - efficiency, operation stability, accuracy of model production, physical and mechanical properties of produced models - are investigated. Main kinds of waste and causes for its occurrence are analyzed, and ways of their elimination are found. Relying upon the experience of this system application a technical assignment has been elaborated for production of Karat-400, a LOM system of the next generation.

The influence of the structure of the holey-fiber cladding on the spectral broadening of femtosecond laser pulses is experimentally studied. These experiments demonstrate that the spectral broadening of 70-fs pulses of 800 nm Ti:sapphire laser radiation transmitted through 2- and 3- micrometers -pitch holey fibers can be enhanced by a factor of about 1.5 by increasing the air-filling fraction of the fiber cladding from 16 up to 65%. The main physical factors influencing the phase distribution and coherence properties of broadly spanning frequency combs produced with the use of holey fibers are considered. Phase shifts and spectral distortions arising due to dispersion effects, modulation instabilities, and shock waves of pulse envelopes are explored, and general recipes to reduce the influence of these effects by means of fiber optics are discussed.

The quantum theory of nonlinear dynamics and self-switching effect for two coupled waves in nonlinear distributed feedback systems (DFB) have been developed using Hartree approximation for the first time. The quantum limits of observation of self-switching effect for the polarization characteristics of light have been founded. We also predict the formation of nonclassical mesoscopic states (Schroedinger cat like states) of light in such systems as well.

New methods for production of pseudo-nondiffracting Bessel light beams with phase singularities of different topological charge have been developed and proved experimentally. It is found out that nonlinear-optical processes of frequency doubling and sum-frequency generation allow to control formation and annihilation of dislocations. The possibility of realization of arithmetic operations using this principle is proved. When Gaussian beam interferes with M-order Bessel beam having M-order dislocation, the dislocation disintegrates on M parallel quasi-nondiffracting beams packed compactly. Rotating of optical beams aggregate on required angle takes place when phase difference between interfering fields is modulated. New principle of optical inter-connections is proposed on this base.

In the work the various types of holographic recording in the media based on organic dye methylene blue (MB) in polymer matrices are investigated. An interest to this subject is due to the employment of MB as the basic element or the sensitizer for many recording materials and as effective generator of singlet oxygen too. Three forms of holograms are observed and investigated: relief-phase holograms with diffraction efficiency more than 20% recorded in pulse regime; photochemical amplitude holograms based on MB photobleaching; dynamic triplet holograms. The mechanisms of recording and the scope for erasing of holograms are analyzed.

The precision technique for side polishing of single-mode quartz fibers is developed. The technique comprises cutting curved groove in silica block, gluing a section of bare fiber into the groove, and subsequent grinding and polishing of the silica block/fiber assembly. We succeeded in fabricating up to six side-polished fibers in one block with effective interaction length 2-4 mm. The accuracy of polishing depth was achieved at 1 micrometers using in-situ monitoring of transmission of 1.3 micrometers laser light through the fiber. The developed technique combines high accuracy, reproducibility and low cost in commercial production. Side- polished single-mode fibers fabricated with this technique can find application as elements of Bragg grating transmission filters, narrowband reflectors, optical add/drop multiplexers, couplers, polarizers, sensors, etc.

The near field response of semiconductor nanostructure is theoretically investigated for the collection mode of scanning near-field optical microscope (SNOM). We calculated the near-field distribution on the observation plane for several physical systems, in which the semiconductor nanostructure is approximated by the right-angled object with dielectric function including the contributions from the lattice and the free charge carriers. Our calculations take into account the nanoscale objects presence on and under the surface with electromagnetic evanescent waves which are induced by plane excitation light under condition of total reflection wave in SNOM. All calculations are carried out by using self-consistent integral equation formalism. This treatment is based on the field- susceptibility Green's function technique applied in real space. As a result we show that the near-field distribution is essentially dependent on the quantity of charge carriers and on its kinetic properties and also on the configuration of the system.

The technology of dense wavelength division multiplexing (DWDM), which is widely used in modern optical fiber communication networks for increasing bit rates, requires development of advanced Bragg grating filters with improved rectangular-shaped reflection/transmission spectra and linear phase characteristics within the stop/passband. Such spectra cannot be achieved with uniform Bragg gratings, and therefore nonuniform gratings with space-modulated amplitude should be developed. We present the new approach to the design of nonuniform grating profiles, which is based on utilization of superimposed biharmonic gratings with sinusoidally modulated amplitude and periodically located distributed phase shifts (pi) . With this approach Bragg grating profiles possessing narrowband rectangular-shaped transmission spectra are designed using coupled-wave theory and computer simulations.

The practical methods of formation of multi-ring and multi- beam gradient light fields are proposed and experimentally realized. These methods are based on the use of crystals, refracting elements with different configurations, and special optical resonators. The obtained gradient light fields have geometrically regular spatial intensity distributions and different types of symmetry. The process of second harmonic generation with gradient light fields was investigated. Gradient light fields and their second harmonic have promising perspectives both for optical information processing and for some technologies, such as cool particles control in nanotechnologies, operations with organic cell and its components, local radiation material processing, and production of some periodic structures.