This PDF file contains the front matter associated with SPIE Proceedings Volume 7996, including the Title Page, Copyright information, Table of Contents, Introduction (if any) and the Conference Committee listing.

Here we present the results of mathematical, numerical, and experimental simulation of the processes of interaction between the laser radiation and metals in the technologies of gas-laser cutting of thick-sheet materials and laser gas-powder cladding at the production of coatings and 3D objects by the DMD (Direct Material Deposition) method. The peculiarities of jet 3D flows of the working gases in narrow channels, geometrically identical to keyholes, are studied. It is demonstrated that during the stainless steel cutting, supersonic gas flows form local regions of separation flows which in turn result in the worse carry-away of the metal by the gas flow; these factors increase the roughness (striation) and worsen the surface quality. A vortex flow was found inside the cut at the subsonic jet flows typical for the oxygen gas-laser cutting of low-carbon steel; this flow causes slagging of the cut bottom edge. The processes running inside the laser cut at the fusible metals cutting with the low-power radiation were visualized under the laboratory conditions. Some new concepts of the processes running inside the keyhole have been gained; we also propose the explanations of the mechanisms of striation and other surface defects formation during the cutting of thick-sheet standard metals on the automate laser technological complex. A mathematical model of the volumetric laser-powder cladding is proposed. The submitted results concern the numerical simulation of multi-layer flows of shaping and carrier gases with the gas-jet transportation of powder particles into the laser spot on the substrate.

Stealth dicing (SD) is an innovative dicing method developed by Hamamatsu Photonics K.K. In the SD method, a permeable nanosecond laser is focused inside a silicon wafer and scanned horizontally. A thermal shock wave propagates every pulse toward the side to which the laser is irradiated, then a high dislocation density layer is formed inside the wafer after the thermal shock wave propagation. In our previous study, it was concluded that an internal crack whose initiation is a dislocation is propagated when the thermal shock wave by the next pulse overlaps with this layer partially. In the experimental result, the trace that a crack is progressed gradually step by step was observed. In this study, the possibility of internal crack propagation by laser pulses was investigated. A two-dimensional thermal stress analysis based on the linear fracture mechanics was conducted using the stress distribution obtained by the axisymmetric thermal stress analysis. As a result, the validity of the hypothesis based on a heat transfer analysis result previously presented was supported. Also it was concluded that the internal crack is propagated by at least two pulses.

The results of research work on laser modes influence on contrast ratio and on microgeometry of marks created on the finished surface of beryllium gyro details are described. Within the research the possibility of getting the required contrast ratio 0,7±0,1 on the wave length 860 nm due to laser marking usage is presented.

Experimental results and theoretical estimations of the color image formation by laser oxidation of steel surface are considered. Method of laser radiation parameters selection to provide desirable color is offered. Influences of diffraction effects to the metal surface color characteristics are analyzed.

For obtain nanostructured surfaces on various materials the method of laser deposition of metals from solutions (LDMS) was used. As a solution were used nanosystems: oxide copper (CuO) and a two-component solution of nickel (Ni) and carbon nanotubes. Deposition occurred action of pulse-periodic laser radiation (a wave length 1.06 microns, a pulse length 100ns, a repetition rate of impulses 20 kHz) various power. Laser radiation was focalized on a substrate from a quartz glass and copper. Obtain samples were research on a raster-type electronic microscope (Quanta 200/3D) and an atomic-force microscope (Ntegra Aura). As a result deposition occurred only on a trajectory of a motion of a beam. Deposition layers has good adhesion to a substrate surface. <<The soft mode>> actions of laser radiation as the substrate surface is not exposed to thermal action. The layer roughness made 270nm at height of a relief about 2 microns. The offered method of deposition of metals from the colloid solutions by means of laser radiation is simple, inexpensive, and to substrates scaled to the big areas and length of the precipitated layer.

Laser thermochemical method (LTM) of writing the information on thin Cr films is used for fabricating of diffractive optical elements (DOE). LTM is based on local laser oxidation of thin Cr films and following selective etching. It seems to be an alternative method to photolithography and laser ablation of thin films. The quantity of technological operations is much less then at photolithography and there are no thermal and hydrodynamic distortions at LTM as at laser ablation. Nowadays, DOEs are widely used in different devices, especially in modern telescopes, micro lens arrays, laser optics etc. The main parameter for all types of DOE is high spatial resolution. It implies a tendency to reduce the pulse duration up to femtosecond range. This, in turn, requires the detail knowledge of the physical and chemical processes in thin Cr films under ultrashot laser irradiation, to study them is the aim of present work.

Nowadays there is tendency to search new materials which have specific properties in various fields of practical applications including microelectronics and optoelectronics. These materials can be applied for fabrication of new type of devices. Fabrication of glass-ceramic films by method of laser-induced local transfer is interesting purpose. Glass-ceramic films can be applied for forming of micro-optic elements, elements of microelectronic and optoelectronic circuits. Process of laser-induced local transfer of sitall ST-50-1 by fiber laser (λ=1,06 μm) was investigated and its features were revealed. Film coverings having properties of polycrystalline glass-ceramic films were carried out by laser-induced local transfer of material from ST-50-1 sitall donor plate to K8 glass acceptor substrate. Estimation of deposited films quality and its thickness was carried out and optical properties were investigated.

The experimental study regarding the laser bending of sheet metal parts of various shapes at different irradiation conditions is reported. The present work is carried out using Nd: YAG laser (average power of 200 W, pulse duration of 0.1 - 10 ms). Plates made of alloyed steel of various grades and having thickness from 0.3 to 1.1 mm were used as samples. Formation of laser beam path on the odd-shaped parts was executed by the programmable 6-axis robot Motoman SSF-2000.

The optical systems for temperature monitoring of SLS/SLM process are developed and integrated with industrial SLS/SLM machines. The system provides the possibility to spatial distribution of brightness temperature at two wavelengths and selected temperature profiles, calculation of colour temperature and express analysis of possible deviations of the maximum temperature from its optimal value. Optimal regimes of SLS process for the sintering of the high porosity powder body was determined.

Some optical schemes for the production of conical beams with high cone angle and a quasi-uniform axial distribution of the intensity have designed and a elaborated method of laser power delivery in heterogeneous stream are used for nanopowder production and SLC process modification. The new principles of laser pulse generation are elaborated and optical schemes for production of a volumetric laser beams, convergent spherical and cylindrical have been designed. On the base of laser system developed and concept of quasitransparent first wall the reactor construction design intent has been proposed.

This paper proposes a variant of application of a decision support system (DSS) in order to form a set of laser micromachining system configuration parameters on the basis of previously created knowledge base. It is shown that use of quality control module developed by authors on the basis of optoelectronic sensors and software tools allows the simplification and automatization of a data collecting process for DSS. Software and hardware elements that were developed allow making the semiautomatic adjustment of the system for a specific micromachining task solving, assessment of the experiments results and saving obtained data in the knowledge base.

This paper presents the results of theoretical and experimental investigations of Er:YLF lasing at wavelengths 2.66, 2.71, and 2.81 um for pulse-periodical diode pumping at wavelength 0.98 um. Considerable change of lasing spectrum with increasing of pulse repetition rate was observed. The new method of tuning lasing spectrum based on this effect was suggested.

ZnO crystals have attracted a great attention for next generation nanodevices because it has a superior crystalline quality, a better electrical/optical quality, a freedom to choose substrate and a large surface area to volume ratio. We have been succeeded in growing nano-structured ZnO crystals by nanoparticle-assisted pulsed-laser deposition without using any catalyst. Not only vertically aligned ZnO nanowires but also horizontally aligned ZnO nanowires have been successfully grown on the annealed c-plane and a-plane sapphire substrates, respectively. Besides, Depending on the PLD growth conditions and the composition of the target, ZnO nanowalls with thickness of tens of nanometers and dimension of several micrometers were synthesized. The room temperature photoluminescence spectrum of such a ZnO nanowall exhibited a strong intrinsic UV emission and a week defect-related visible emission. Synthesized ZnO nanowires were applied to a heterojunction light-emitting diode and an UV photo-sensor. In addition, it was found that the ZnO nanowalls showed stable field emission properties with low threshold field and a big field enhancement factor. Furthermore, layer-structured ZnO nanowires were fabricated by NAPLD using a multi-target changer system.

A general theory is developed for surface-plasmon-enhanced near-field optics and magneto-optics via a linear nanoprobe. Considered as a model is a nanowire located near a sample with an embedded magnetic nanolayer, both nanoobjects being parallel to the surface of the sample. The nanowire is thought of as a thin noble-metal cylinder which possesses long-lived surface plasmons, and so can do the surface of noble-metal sample. With the electrodynamic Green function technique, a resonant polarization response of the complex "probe+image" is treated self-consistently within a multiple-scattering approximation. The magnetization-linear scattering events are classified in terms of TM (p-polarized) and TE (s-polarized) waves, the polarization planes of incident and scattered waves coinciding. The problem of resonant near-field magneto-optics with a linear probe is solved analytically for a nanolayer magnetized along its normal (polar magneto-optical Kerr effect). As well, in varying the in-surface distance between the near-field probe and a laterally nanosized magnetic domain, the scanning near-field microscopy in scattering mode is treated. Polarization, angle and spectroscopy characteristics of the magneto-optical resonant scatterings due to a nanowire are found and shown to differ principally from those due to a quasi-point probe. Resonant enhancement of scattering efficiency due to coupled surface plasmons of a nanowire and a sample is estimated.

Wet-chemical-assisted femtosecond (fs) laser ablation has been developed for high-efficiency, high-quality nanofabrication of gallium nitride (GaN) surface. In this technique, an fs laser beam is focused on the surface of a single-crystal GaN substrate immersed in 35% hydrochloric (HCl) acid by a high-numerical-aperture objective lens. This method produced higher quality ablation craters with sharper edges, smoother surfaces, and less residual debris than conventional fs-laser ablation in air followed by etching in HCl (two-step processing method). This is presumably due to a photochemically or photothermally assisted chemical reaction associated with the HCl acid solution. Using the second harmonic of an fs laser (λ = 387 nm), nanocraters with diameters as small as 320 nm (full width at half maximum) were formed at a GaN substrate surface. Assuming that this process is based on two-photon absorption, we theoretically calculated the diameters of ablation craters. The calculation results agree well with the experimental results, particularly in the low-energy region. Multiscan irradiation was performed to fabricate a two-dimensional (2D) array of nanoholes with a high aspect ratio of ~1.6, which is much higher than that obtained using single-pulse irradiation. The aspect ratio was found to depend on the refractive index of the medium above the GaN substrate. The fabricated 2D array of nanoholes on a GaN surface could be used as a 2D photonic crystal for enhancing the light extraction efficiency of GaN-based blue LEDs.

Non-thermal light-induced surface processes hold out hope for the development of new approaches to surface nanostructuring. Although they do not seem to be as flexible and universal as photolithography a number of niche application are waiting for a specific cheap and easy process. The light induced atomic desorption is a reliable tool to control the surface number density of the adsorbed atoms in the course of the physical vapor deposition process. The strong enough illumination diminishes the number density of the adsorbed atoms below the threshold value needed for the beginning of the nucleation process. Hence, the deposition pattern reproduces the distribution of the illumination intensity over the surface. In some cases plasmonic nanostructures are obtained via self organization of metal deposits on dielectric substrates. Their performance is severely hindered by the broad size and shape distributions. The non-thermal light-induced detachment of surface atoms from the metal nanoparticles may be used to tune their size and shape. In particular, we find that a narrow dip in the shape distribution of the metal nanoparticles may be obtained by the laser treatment at the specific wavelengths.

Layers of carbocyanine polymethine dyes were studied to evaluate the effect exerted by the molecular structure and thickness of a layer on its component composition. Thin layers contain cis-monomers of different structure as major form. The number of types of cis-isomers decreases and the relative concentration of the all-trans isomers increases with increasing thickness. As the electron-donating ability of end groups and the chain length grow, the number of stereoisomers of different types increases. It was concluded that the equilibrium stereoisomeric composition of the layer is determined by degree of asymmetry, which is induced in the intramolecular electron density distribution by the interaction with substrate. We developed the model for rearrangement of layer by heating and photoexcitation. Reversible changes in the component composition are due to the stereoisomerization upon rotation of a molecule fragment around the second polymethine chain bond and irreversible changes, due to the change in asymmetry of the electron density distribution owing to irreversible spatial reorientation of layer components. The spatial reorientation of layer components is determined by stereoisomerization upon rotations around the central bonds.

The objective of this combined experimental and theoretical research is to study the dynamics and mechanisms of nanoparticle interaction with ultrashort laser pulses and related modifications of substrate surface. For the experimental effort, metal (gold), dielectric (SiO2) and dielectric with metal coating (about 30 nm thick) spherical nanoparticles deposited on glass substrate are utilized. Size of the particles varies from 20 to 200 nm. Density of the particles varies from low (mean inter-particle distance 100 nm) to high (mean inter-particle distance less than 1 nm). The nanoparticle assemblies and the corresponding empty substrate surfaces are irradiated with single 130-fs laser pulses at wavelength 775 nm and different levels of laser fluence. Large diameter of laser spot (0.5-2 mm) provides gradient variations of laser intensity over the spot and allows observing different laser-nanoparticle interactions. The interactions vary from total removal of the nanoparticles in the center of laser spot to gentle modification of their size and shape and totally non-destructive interaction. The removed particles frequently form specific sub-micrometer-size pits on the substrate surface at their locations. The experimental effort is supported by simulations of the nanoparticle interactions with high-intensity ultrashort laser pulse. The simulation employs specific modification of the molecular dynamics approach applied to model the processes of non-thermal particle ablation following laser-induced electron emission. This technique delivers various characteristics of the ablation plume from a single nanoparticle including energy and speed distribution of emitted ions, variations of particle size and overall dynamics of its ablation. The considered geometry includes single isolated particle as well a single particle on a flat substrate that corresponds to the experimental conditions. The simulations confirm existence of the different regimes of laser-nanoparticle interactions depending on laser intensity and wavelength. In particular, implantation of ions departing from the nanoparticles towards the substrate is predicted.

Electrical as well as photoelectrical properties of the metal nanoparticle ensembles (MNEs) were investigated. The exponential temperature dependence of the conductivity in the MNEs was obtained. Since lnIc depends linear on 1/T, an activation energy concept of the conductivity can be applied. An activation energy of Eact = 0.50 eV for Ag nanoparticles has been extracted. The photoconductivity of MNEs has been related to their extinction spectra. A clear evidence of the photoinduced conductivity of the MNEs was obtained. Considerable enhancement of the photocurrent was observed for those wavelengths that are in resonance with plasmon excitations localized in the metal nanoparticles forming the MNE. The increased photoconductivity can be explained by the additional energy placed in the nanoparticles due to the excitation of an LSPPR.

Films based on oxides of transitional metals have semiconducting properties that make them up-to-date materials for functional electronics. The reactive pulsed laser deposition (RPLD) allows the control of thickness and stoichiometry of deposits in order to obtain semiconductor structures with accurately tailored thickness and band gap. It is very important to study electrical, structural and optical properties of these semiconducting nanometric films, as sensing characteristics strongly depend on these properties. We deposited iron oxide (Fe₂O_3-X; 0 ≤ x ≤ 1) and chromium oxide (Cr_3-XO_3-Y; 0 ≤ x ≤ 2; 0 ≤ y ≤ 2) films on <100> Si substrate by RPLD using a KrF laser. The deposited nanometric films (thickness 50-200 nm) of iron and chromium oxides have large thermo electromotive force (e.m.f.) coefficient (S). The S coefficient of iron oxide films varied in the range 0.8-1.65 mV/K in the temperature range 210-322 K. The maximum value of the S coefficient (1.65mV/K) was measured in the temperature range 270-290 K. The largest photosensitivity (F) of iron oxides films was about 44 Vc/W for white light at power density (I) of about 6×10^-3 W/cm². As regards chromium oxide films, the S coefficient varied in the range 0.30-4.5 mV/K in the temperature range 210-333 K, with the maximum of 3.5-4.5 mV/K in the temperature range 270-290 K. The largest photosensitivity of chromium oxide films was about 2.5 V_c/W at I≅6×10^-3 W/cm². Our results show that RPLD is a very simple procedure to synthesize of iron and chromium oxide nanometric films with variable stoichiometry and, consequently, with different values of their band gap result in variable the S coefficient and the photosensitivity (F). The deposited films present large thermo e.m.f. coefficient and high photosensitivity that make them up-to-date materials for photo-thermo sensors.

We present the results of analytical and numerical study of spatial distribution of the fluctuating electric field near the surface of a model ionic crystal as a function of temperature. The potential variance is calculated and it is shown that the fluctuating field power density decays outside of the crystal as h^-3, where h is the distance from the crystal suface. When h > 6a (a is the lattice period), the fluctuating field exceeds the static field, which decays exponentially. At these distances, the chatacteristic strength of the fluctuating field lies in the range of 10⁶V/cm. The fluctuating potential variance squared grows linearly at high temperatures and does not vanish at 0 K. The effect of the fluctating electric field on formation of nanostructures on the crystal surface is considered.

We suggest a separation of variables method based on expansions of the electromagnetic fields in terms of spheroidal wave functions. Our approach includes splitting the fields in two specific parts and choice of proper scalar potentials for each of them. An earlier analysis of similar methods in the case of a spherical basis has shown that the SVM has a wider practical applicability range than other methods. It was also found that when using a spheroidal basis our general approach gave reliable results for particles of high eccentricity for which other approaches were inapplicable. Thus, the suggested SVM should be highly efficient in calculations of optical properties of various nonspherical scatterers in a wide range of parameter values.

An experimental results causing the resonant periodic microstructures formation under the action of femtosecond laser radiation on metal surface in dependence on higher threshold energy density are considered. The simple system consisting of vacuum-homogeneous electron plasma boundary is used to analyze dispersion relation of surface plasmon polariton supported by this boundary. Obtained using theoretical dispersion relation the microstructure period dependence on laser energy density shows limited rise in agreement with experimental data.

Dynamics of optical properties of semiconductor during action of femtosecond laser pulse is theoretically studied taking into account different types of electron emission. Calculated spatial distribution of dielectric permeability is modelled in multi-layered samples and experiment on surface plasmon resonance is performed. The experimental data is compared to surface periodic micro-structures experimentally observed in silicon under femtosecond laser action.

Localized phase separation was induced inside a glass, the composition of which is not immiscible, by femtosecond laser-induced compositional modification. The glass composition was changed locally from a miscible composition to an immiscible one with high-repetition femtosecond laser irradiation. The phase separation was confirmed by analyzing the composition of the irradiated area with confocal Raman spectroscopy and by observing the co-continuous structure due to phase separation with scanning electron microscopy. The compositional change seems to be related to thermomigration, which is the migration of atoms or ions by the temperature gradient, because the sharp temperature gradient is caused with a high-repetition femtosecond laser. With this method, we can obtain nanoscale co-continuous structure, which would have high surface area, on a glass surface. Moreover, we can control the morphology of the structure by heat treatment while avoiding phase separation in the entire glass because the composition of the non-modified region is not immiscible.

In this paper laser-induced modification of photosensitive glass-ceramic materials under YAG:Nd second harmonic picosecond pulses is observed. The method for such modification based on laser processing and subsequent heat treatment is developed. The comparison for infrared femtosecond modification is introduced.

In this paper the results of research of influence of laser emission on electrophysical and structural parameters of SiO₂/Si system are given. Research samples were irradiated with optical fiber YLP-laser (λ=1,06 μm) with 250ns pulse length. Power of emission in impulse was (2-4) - 7,13 Wt/sm² . As experimental sample thermal oxidated silicon base KEF-4,5 was used, which crystallographic plane was similar to (100). As a result of experiments it is shown that laser irradiation of Si/SiO₂ system can form SiO₂+silicon nanoclusters system on silicon film. Nano-engineering of SiO₂/Si system is accompanied by essential changing of electrophysical properties of initial MOS structures.

The paper is devoted to experimental and theoretical studies of ablation of condensed matter by optical (OL), extreme ultraviolet (EUV) and X-ray lasers (XRL). Results obtained at two different XRL are compared. The first XRL is collision Ag-plasma laser with pulse duration τ_L = 7 ps and energy of quanta hv=89.3 eV, while the second one is EUV free electron laser (EUV-FEL) and has parameters τ_L = 0.3 ps and energy of quanta 20.2 eV. It is shown that ablation thresholds for these XRL at LiF dielectric are approximately the same. A theory is presented which explains slow growth of ablated mass with fluence in case of XRL as a result of transition from spallative ablation near threshold to evaporative ablation at high fluencies. It is found that the metal irradiated by short pulse of OL remains in elastic state even in high shear stresses. Material strength of aluminum at very high deformation rates V/V ~ 10⁹ s^-1 is defined.

Ultrashort laser pulse interaction with material involves a number of specialities as compared to longer irradiations. We study laser heating of metal by femtosecond pulse with taking into account electron photo- and thermionic emission leading to accumulation of a high positive charge on the target surface and, thus, to the generation of the electric field which causes Coulomb explosion (an electronic mechanism of ablation). Also emission slightly influences the thermal and optical properties of solids.

The expansion of plasma plume produced by a laser ablation is investigated using the self-similar approach. Based on the fluid model and the quasi-neutral assumption, the one dimensional expansion of an either vapor or partially ionized gas is studied for a collisionless plasma in the presence of electrons in thermal equilibrium. The uniqueness of the self-similar solution is questioned. Two different self-similar transformations for the ion density are proposed, one commonly used for free plasma expansion and the other corresponds to the expansion with diffusion. The density profiles and the self-similar parameter limit, corresponding to the end of the expansion, are found to be strongly affected by the transformation. A comparison is made with experimental results of a plasma produced by nanosecond laser pulse interacting with a metallic titanium target in a vacuum.

A study of the laser ablation of a ZnO target has been carried out in vacuum, by using a Nd:Yag laser with a pulse duration of 3 ns, a wavelength of 532 nm and a maximum pulse energy of 150 mJ. The measurements of ablation yields, crater profiles and fast CCD plasma imaging allowed the evaluation of the plasma density. Time-of-flight (TOF) measurements have been also utilized to monitor the ion emission by using a special ion collector placed along the normal to the target surface. Coulomb-Boltzmann-shifted ion energy distributions have been obtained depending on the ions charge states. The plasma temperature was evaluated by such ion energy distributions of the experimental data. A special attention has been devoted to the ion acceleration processes due to the high electric fields generated inside the non-equilibrium plasma. The characterization of the latter and the deposition of ZnO thin films are correlated and discussed.

The results of investigations of metal surface destruction , plasma formation and evolution on exposure to quasicontinuous pulsed laser under high pressure (up to 1.6 MPa) of ambient nitrogen are presented.

A one-fluid, one-dimensional magneto-hydrodynamic (MHD) model is used to investigate the dynamics of magnetized laser produced plasma expanding into vacuum, just after the termination of the laser pulse. The created plasma plume is assumed to be fully ionized containing electrons and singly charged ions and considered to be under local thermodynamic equilibrium, allowing all charged particles to have same temperatures. A selfsimilar solution is found to describe the expansion of the plasma satisfying ideal time-dependant MHD equations where charge quasi-neutrality is assumed to prevail. The evolution of the transverse magnetic field is supposed to follow Faraday law and the set of obtained differential equations is closed with an ideal equation of state. The numerical results report the behaviour of the deduced plasma parameters like density, velocity and temperature as functions of the self-similarity variable for different increasing initial values of magnetic field. We find that the interaction of the plasma with the transverse magnetic field may cause significant changes in the plume expansion dynamics, including confinement of the plasma leading to the increase of particles arriving on the substrate. Velocity plasma increase is also observed due to the Lorentz force that accelerates the charges to move faster and further away from the target. The temperature of the plume is found to be larger compared to temperature in un-magnetized plasma, due to Joule heating and magnetic compression of the plume.

Carbon nitride films were synthesized by a KrF excimer laser ablation of a graphite target in a controlled nitrogen atmosphere. The laser fluence was set at 10, 12 and 16 J/cm². These thin films were deposited on <100> silicon substrate kept at room temperature and placed parallel to the target surface at a distance of 3 cm. The pressure of nitrogen was varied from 0.1 to 1 mbar. The deposited films were characterized with different diagnostic techniques. Scanning electron microscopy (SEM) and Atomic force microscopy (AFM) were used to study their surface morphology and to measure their surface roughness. The crystalline structure of the films was analyzed by X-ray diffraction (XRD). Film composition was investigated by Rutherford backscattering spectrometry (RBS) analysis. The bonding structures were performed by Fourier transformed infrared spectroscopy (FTIR). SEM observation indicates that CNx film present a granular structure for all pressures used. Film structure evolves from amorphous to a polycrystalline structure at 16 J/cm². This crystalline structure depends on nitrogen pressure. The carbon plume dynamics was also investigated by fast imaging. This study was performed into 0.2 and 1 mbar nitrogen pressures. The light emitted by the plasma was observed along the perpendicular to the ejection direction through a fast intensified charge-coupled device (ICCD, Princeton Instruments PI-MAX, 1024 x 256 pixels). Different regimes of expansion dynamics have been evidenced. Emission of C₂ and CN were also imaged using interference filters. The CN radical is considered to be the mainly precursor to CN_x growth.

Physical, chemical and tribological properties of the MoSex and MoSe_xC_y coatings for micromechanical applications grown by pulsed laser deposition in vacuum and in a rarefied inert gas (argon) atmosphere are studied. In a number of experiments a disk-shaped screen was used that is placed on the path of the expansion of laser plume in order to trap the droplet fraction. Upon deposition in a gas at a pressure of ~2 Pa, stoichiometric MoSe₂ coatings with improved antifriction properties as compared vacuum-deposited MoSe_x (x<2) coatings form. However, a too strong increase in the argon pressure (to ~10 Pa) degrades the tribological properties of the coating. Deposition in vacuum or argon at a pressure of 2 Pa leads to formation of rather smooth coatings with a dense amorphous structure containing molybdenum nanoinclusions. Numerical experiments based on the combination of two computer models that describe physical processes on the atomic level using Direct Simulation Monte Carlo and Kinetic Monte Carlo methods are performed to reveal the factors that affect the thickness, chemical composition, and structure of the MoS_x-based coatings. Deposition to a negatively biased substrate is shown to substantially increase the coating density and to smooth the surface relief.

A counter-propagating Bessel beam technique is suggested and realized for creation of 2-dimensional (2D) holographic periodic structures (PS) in photorefractive materials. 2D PS formed by the suggested method is a combination of annular and planar gratings. The Bessel beam is formed by optical element - axicon. The recording of the gratings are performed by single mode He-Ne laser beam at 633 nm. The counter-propagating beam geometry builds up the Bessel standing wave with periodic annular structure in each anti-node. The refractive gratings are recorded in Z and Y-cut 2 mm thick Fe doped lithium niobate crystals via electro-optic effect. The read-out of 2D PS is performed by Gaussian and Bessel beams. Diffraction patterns in transmission and reflection are observed. The formed 2D PS have the halfwavelength standing wave period of ~300 nm in longitudinal direction, the period of ~10 μm in radial direction, and up to 10 % diffraction efficiency.

In this article there are considered two methods of increasing of the sensitivity for polymer resists. These resists are used in the process of extreme UV (EUV) lithography. The both discussed methods can be used independently of one another or in turn. The first method supposes usage specific polymers as EUV resists. The increase of the coefficient of absorption in relation to EUV waves is characteristic for these polymers. The second method is applicable only for particular positive polymer resists. This method assumes an additional irradiation of the substrate's plane by the UV light appropriate to the certain spectral range. These waves are affecting exclusively on the earlier formed polymer macro-radicals. So the number of macromolecular ruptures increases in several times only in the areas preliminary exposed by EUV radiation. Moreover the degradation of the linear resolution due to this procedure is small.

A theory is developed for resonant elastic scattering of light from Bragg structures (one-dimensional photonic crystals) which have randomly rough interfaces. The study is mainly focused on the spectral and angle dependences of radiation giving information about static disorder responsible for the elastic scattering. The diffuse reflection spectra for linearly polarized light are computed and analyzed in detail. A resonant enhancement of the scattering cross-section is found to be manifested in the vicinity of the photonic stop-band edges. Angle-dependent suppressing the diffusive component of reflected p-polarized light and strong dependence of the scattering spectrum on the location of a single rough interface are demonstrated.

Cultural Heritage has many analytical and treatment needs both in the field of conservation than in restoration. The laser therefore found a ready-made place in this area. We find first the different application of laser cleaning. The LRMH was the initiative of creating the first field prototype used in the field for cleaning stone in particular. A tour of the Cathedral of France to test this method had been achieved in the early 90s. Then, many have phenomenological and physical studies were conducted to understand the mechanisms involved during the cleaning action. In analytical technology, LIBS (Laser Induced Breakdown Spectroscopy) is used for in situ identification of pigments, salts, metals or other materials. This laser technique present a lot of advantages: portability, analysis of light elements, stratigraphic analysis capability ...The LRMH was the first laboratory depending from a ministry of culture to get the technology and to apply it systematically in situ (Saint-Savin sur Gartemps abbey...). In addition, more recently, a methodology for converting pigments by continuous laser was developed in the laboratory, thus extending the scope of the use of laser. We review these techniques and their application based on studies that occur in our laboratory.

This work is dedicated to spectroscopic investigations of laser spark during the laser cleaning process. The goal is to proof its analytical possibilities for chemical composition determination for online cleaning quality control. Photographic recordings of laser spark were performed to estimate its parameters. Fiber spectrometer was used to analyze the emission of cleaning process established with fiber laser. Conclusions have been made about fiber laser radiation usability for spectroscopic purpose.

It's hard to imagine a modern city view without some drawings and inscriptions, usually called "graffiti". Traditional cleaning methods do not suit modern requirements. Investigation of possibilities of laser assisted paints removing is described in this article. The conditions for removing different paints from different surfaces were defined.

The results of investigations concerning the laser cleaning of polluted rail track and its productivity analysis are presented. The laser applied in the experiments is Q-switched pulsed Ytterbium fiber laser (average power of 50 W, pulse duration of 100 ns). The contaminations were put both on rails of P65 mark and bandages. The estimation of laser cleaning efficiency revealed that there is a possibility to increase the coefficient of friction between the rail and bandage by 30%.