Compact-sized excimer laser with two-side preionization

Compact-sized monopulse excimer laser with the foot-print equal to only 250×80 mm, total height 250 mm and beam axis height 50 mm was designed. Output energy at the wavelength 308 nm (XeCl* mixture) is 5 mJ, maximal repetition rate – 1-2 pulses per second, beam divergence – 8 milliradians. The small foot-print, small axis height of beam in combination with low weight of laser (5 kg) allow this laser to be used in various optical schemes, where traditional, typical bulky ecximer lasers are unapplicable. Moreover, small dimensions, low weight in combination with low energy consumption (a few watts) allow them to be used in clear “field” conditions. Beside abovementioned characteristics, the designed laser differs from the traditional ones by two-side preionization that has a “spark” character near the “hot” massive electrode and the so-called “capacitive” or “barrier” one under the ground grid. This two-side preionization provides both igniting and sustaining of wider discharge thus allowing to reach beam with higher symmetry – its cross-section is 15×20 mm²

On Raman spectra of water, its structure and dependence on temperature

Raman spectra of water within the temperature range 20 to 3 C were investigated. Best of all, the complex shape of the obtained spectra was approximated by four (or five) Gaussian-shaped peaks with their positions 3070, 3230, 3440, 3600 (and 3650) cm⁻¹. The most intensive constituents were 3230 and 3440 cm⁻¹ lines, their total contribution to the Raman spectrum of water is higher than 90%. These lines are the most sensitive to the temperature, too. When the temperature decreases from 20 down to 3 C, the positions of these peaks were shifted from 3232 to 3224 cm⁻¹ and from 3441 to 3434 cm⁻¹, respectively; and the intensity of 3230 cm–1 line was increased approximately by 14% in its magnitud

Precise measurements of the wavelength in KrCl laser spectral region (222 nm)

The technique for precise measurements of wavelengths in the range around 222 nm (45030 cm⁻¹) has been presented. The reciprocal linear dispersion of the spectrometer was 0.529 Å/mm. The measurements were made in the second spectral order for a grating with 2400 lines/mm. Identification of emission lines of hollow cathode lamp (Fe) was made in the spectral range 4428…4452 Å. The wavelengths were measured for 32 identified lines in the spectrum. The mean square error of easurements is ∼0.0005 Å

Surface modification of Ti alloy by electro-explosive alloying and electron-beam treatment

By methods of modern physical metallurgy the analysis of structure phase states of titanium alloy VT6 is carried out after electric explosion alloying with boron carbide and subsequent irradiation by pulsed electron beam. The formation of an electro-explosive alloying zone of a thickness up to 50 µm, having a gradient structure, characterized by decrease in the concentration of carbon and boron with increasing distance to the treatable surface has been revealed. Subsequent electron-beam treatment of alloying zone leads to smoothing of the alloying area surface and is accompanied by the multilayer structure formation at the depth of 30 µm with alternating layers with different alloying degrees having the structure of submicro - and nanoscale level

Advanced modification of main types of excimer laser resonators

In the paper proposed are some simple modifications of plane-parallel and unstable telescopic resonators the most widely used in excimer lasers. These can increase output energy, density of emission power and improve the shape of a laser beam cross-section. Physical essence of these modifications lies in formation of an optically closed zone in some part of the resonator, which prevents photons to escape. This yields in their increased concentration (the so-called `photon concentrator') that favors discharge stabilization and shifting this zone towards a cathode where main instabilities of an electric discharge originate. In the plane-parallel cavity such a photon concentrator can be realized by application of an output window with a mirror area in the range corresponding to the cathode space. Using the scheme in our conditions we observed the increase of laser pulses emission energy by 15% and, respectively, their energy density by 44% with simultaneous decreasing the laser beam shape extent (in its cross-section) and proportional reducing a beam divergency along the diminished size. In the unstable telescopic resonator this kind of a closed zone (photon concentrator) should exist by definition and, as a rule, in a paraxial part of it. The modification proposed consists in shifting this zone towards a cathode. In our conditions this way provided the increase of laser pulse emission energy by 5% with simultaneous improvement of the laser beam shape (in its cross-section). It means shifting a shaded spot towards a border of the beam cross-section and, in such way, to its practical removal out of operating beam

Multiwave laser source for simultaneous sounding ozone and critically related to ozone chemicals

The scheme of multiwave laser source, suitable for simultaneous probing ozone and chemicals critically related to ozone (such as HCl, ClONO₂, N₂O₅, HNO₃) participating in its formation and destruction, when using differential absorption with scattering method (DIAS) for sounding, is suggested. Such a source may consist of excimer laser complex complemented with a converter implementing Stimulated Raman Scattering phenomena. Both complex and converter are assembled and operate using “oscillator-amplifier” optical scheme, which provides simultaneous generation at few wavelengths in a wide spectral range due to discrete Raman conversion with its fine tuning due to complex implementation. Experimental pattern of 3-waves laser source elaborated with this scheme is described. In our attempt laser source consists of XeCl*-excimer laser complex supplemented with SRS-converter with dense hydrogen. Possibilities of simultaneous generation at three lines - 308, 353 nm and one of the wide set: 414, 499, 635 or 855 nm – with fine tuning of all lines within up to 1 nm are demonstrated. The advantages of offered scheme and difficulties in its realization are discussed