Using a micro-hole grating in a supported silver film as a laser-fabricated novel optical platform for surface-enhanced IR absoprtion/reflection spectroscopy, characteristic absorption bands of Staphylococcus aureus, especially – its buried carotenoid fragments – were detected in FT-IR spectra with 10-fold analytical enhancement, paving the way to spectral express-identification of the pathogenic microorganisms.

Purpose of the work is to prepare multilayer coatings corresponding to specified requirements to recovery and improvement of surface details. Requirements to coatings: providing durable and reliable adhesion base and filler materials, absence of pores, cracks, delaminations, reducing mixing metal base and cladding. We used iron-based PR-10R6M5 and tungsten carbide Hoganas 44712 powders. Experimental determination of the optimal technological mode of application of the single track, the coefficient of overlapping tracks to create a full layer, the angle of the second cladding layer, relative to the first one and, finally, the determination of the optimal additive tungsten carbide to achieve increased durability were produced to fulfill these requirements.

In this work it is shown, that laser with injection of reflected radiation can possess the high longitudinal spatial selectivity. Laser figures here both the emitter and the detector of radiation. This attribute, having volumetric character for laser fields, can be considered as a new modality in optical microscopy. Using the experimental possibilities we achieved the spatial resolution at a level of several microns. The optimization of laser sources is to lead to longitudinal spatial resolution at a level of nanometers.

The properties of the plasma that results from the laser welding of metals at various powers of the 10-kW ytterbium-doped fiber laser are experimentally studied. A projection system with an image intensifier based on a copper-vapor laser is employed for the direct observation of metal surface in the course of the laser welding in the presence of the high-intensity background illumination. A method for the shadow photographing is proposed for the analysis of the presence of metal vapor in plasma, since such vapor can lead to the reflection of the laser radiation in the course of welding.

The results of an in-situ plume-laser interaction measurement during welding of mild steel with a 5 kW ytterbium fiber laser are reported. A measurement of the attenuation of probe laser beam passing through the plume has allowed to estimate the plume characteristics like the size of the extinction area and the spatial distribution of the extinction coefficient. The power loss of the fiber laser radiation propagating through the whole plume length was calculated. Together with a measured temporal characteristics of extinction the result indicates a significant decreasing of the laser radiation stability, which can lead to the formation of the macroscopic welding defects.

The effect of the radiation of the pulsed fiber laser on the surfaces of cylindrical samples made of the VT16 titanium alloy is studied. It is demonstrated that the irradiation at appropriate parameters of the laser radiation in the inert-gas (argon) atmosphere leads to an increase in the microhardness of the surface layer and a decrease in the surface roughness of the irradiated samples by a factor of five in comparison with the roughness of the original samples.

The method allowing to detect in real time the laser radiation reflected from metal. in course of its processing by powerful fiber ytterbium lasers is proposed. it is shown that there is a correspondence between the behavior of a reflected back signal; and the oscillatory Processes in a liquid bath of the fused metal.GRAPHICS]Dependence of the number of peaks per unit time on the power of the incident radiation. (C) 2010 by Astro Ltd Published exclusively by WILEY-VCH Verlag GmbH & Co KGaA

A diode-pumped continuous-wave Nd:YAG laser with two linear and mutually orthogonal polarized components of radiation at a wavelength 0.532 μm is studied theoretically and experimentally. The cavity configuration for the realization of generation in this region is suggested. Stable lasing with two mutually orthogonal polarized components is implemented within the range of the intercomponent separation practically from zero to approximately 10 GHz.

The results of development of two versions of the intracavity laser refractometry in reflection (ILRR) are reviewed in this paper. The ILRR method is based on the use of the properties of two-mode lasers with broken cavity and allows the precise refractive investigations of turbid media to be fulfilled in real time. The ILRR applications are primarily planed to biological liquids study. The results of blood refractometry are offered.

In view of its potential for the intracavity laser refractometry, He-Ne laser with two orthogonally polarized modes at wavelength of 1.15 mu was studied. The amplitude and frequency characteristics of this laser were investigated theoretically and experimentally. It has been shown that stable two-mode lasing may be implemented for any split between modes upon applying the transverse magnetic field.

The influence of intracavity second harmonic generation on the mode competition in a double-mode diode-pumped Nd:YAG laser is studied theoretically and experimentally. Various configurations of the optical cavity with II-type phase-matching frequency-doubling crystals are considered. The conditions of steady-state lasing and of lasing with a small level of amplitude pulsation in the output laser beam are determined.

The performance of a linear three-mirror coupled-cavity Nd:YAG laser is studied both theoretically and experimentally for various ratios of the compartment lengths and various geometries of the compartments.

The mode competition in a double-mode diode-pumped Nd:YAG laser is studied theoretically and experimentally. In particular, the influence of various laser parameters on the steady-state double-mode regime for parallel and orthogonal polarization of the modes is studied. It is shown that the establishment of steady-state double-mode lasing is accompanied by relaxation oscillations more complicated than for single-mode lasing. It is found that the scanning rate of the cavity modes influences the character of the relaxation oscillations.

In view of its potential for the intracavity laser refractometry, He-Ne laser with two orthogonally polarized modes at wavelength of 1.15 μ was studied. The amplitude and frequency characteristics of this laser were investigated theoretically and experimentally. It has been shown that stable two-mode lasing may be implemented for any split between modes upon applying the transverse magnetic field.

We present the results of experimental and theoretical studies of amplitude and frequency characteristics of a double-mode He-Ne laser with linear- and orthogonal-polarized modes with the optical length of the cavity modulated with a frequency Omega approximately equal to the intermode-beat frequency. We investigate the regime of synchronous modulation (mode locking) of two orthogonal-polarized modes, when the difference of mode frequencies is completely determined by the modulation frequency. The main specific features arising in the behavior of the mode-locking area and the mode-locking band in response to variations in the operation parameters of the laser and the modulation frequency of the optical cavity length are examined. The behavior of the intensities of separate modes and the intermode-beat frequency on the boundaries of the mode-locking area is analyzed for different directions of cavity-mode scanning.

Intensity behavior of a single-mode diode-pumped Nd:YAG laser with frequency scanning is studied experimentally and theoretically. The specific features in the behavior of the frequency of relaxation oscillations and the oscillation area in response to variations in the magnitude and direction of the scanning rate and working parameters of the laser are determined.

Intensity and intermode beating frequency fluctuations of a two-mode He-Ne laser with a phase-anisotropic cavity and orthogonally polarized modes in a regime of synchronization have been studied both experimentally and theoretically. It is shown that synchronization yields a considerable reduction of the spectral density of fluctuations in the intermode beating frequency.

The influence of mode locking on the spectrum of natural fluctuations of intensity and the frequency of intermode beating in a He-Ne laser is studied experimentally and theoretically. A substantial decrease in the spectral density of fluctuations of the intermode beating frequency in the frequency range omega less than or equal to Gamma is revealed. The value Gamma is close to the range of detunings of the modulation frequency from the frequency of intermode beating where the regime of mode locking can be implemented.