Home – Home – Jornals – Atmospheric and Oceanic Optics 2013 number 10

We considered the characteristics of modernized measurement complex of Siberian Lidar Station (SLS), as well as some other lidar installations, developed at V.E. Zuev Institute of Atmospheric Optics, Siberian Branch, Russian Academy of Sciences, in collaboration with Tomsk State University, and their capabilities for sensing the atmospheric parameters. The lidar measurements of the vertical profiles of temperature are presented and compared with balloon-sonde and satellite data. A lidar for measurements of the vertical ozone distribution in the upper troposphere–stratosphere is described. The reconstructed profiles of the vertical ozone distribution are presented. We give the results of test experiments on laser sensing of the atmospheric gas composition with the help of IR lasers, promising for gas analysis.

Using the method of optical breakdown clipping on Krypton Fluoride excimer laser, ASE (Amplified Spontaneous Emission) pulse compression technology was studied in this paper. And the liquid medium breakdown depth on the ASE pulse compression effect was analyzed. The initial ASE pulse width was 16.8 ns; the shortest 8.4 ns ASE pulse was obtained in the experiment. The auxiliary beam induced luminescence breakdown was used to study on the law of optical breakdown clipping, and the short 7.3 ns ASE pulse was got. These experimental results proved that the auxiliary beams are useful to accelerating the plasma generation rate and duration. The results ASE pulse compression can be controlled in some degree.

Preliminary test data for an original configuration of a multimedia metal vapor laser emitter are presented. The emitter is promising for many applications, in particular, for remote sensing of atmosphere parameters. The novelty of the approach is that two (strontium and copper bromide vapor) gas discharge active elements are placed into a common cavity and each of them is pumped separately from an independent power supply. This permits one to optimize them independently by excitation conditions and, consequently, makes it possible to timely regulate the total set of generation wavelengths and their relative distribution with respect to power in the output beam. This makes the described construction very attractive for a series of scientific and technological applications.

Results on modification of improved synthesis and growth technologies of doped GaSe crystals, design of characterization methods and results of investigation of physical properties, design of tunable mid-IR and wide spectral bandwidth THz parametric frequency converters, first results of its applications in applied spectroscopy are summarized.

We report on the phase-matched high harmonic generation from N₂ gas cell. By varying the laser focus position in the gas cell, we observe the harmonics emission in different position of gas cell. Our results suggest that this source is a potential source for studying ultrafast molecular dynamics

Laser action in gas mixtures of different gases with NF₃ and SF₆ pumped by a volume diffuse discharge formed in nonuniform electric field by run-away electrons (REP DD) is studied. Efficient lasing on HF(DF) and nitrogen molecules was demonstrated. Laser action on atomic transitions of Ne (λ = 585,3 nm, Ar (λ = 750,3 nm), F (λ = 712,8 и 731,1 nm), and on XeF* molecules (λ = 351 and 353 nm) was studied, as well. It was shown that the volume discharge initiated by run-away electrons (REP DD) in gas mixtures with SF₆ is a source for efficient excitation of gas lasers on HF, DF, и N₂ molecules.

The spectral characteristics of high harmonic generation are studied by applying Xe–He mixture gas cell. The cutoff position of harmonics in mixed gases is extended from the 21st to the 27th. In addition, we found the destructive interference of harmonics in Xe–He mixture.

The mathematical model of the XeF(C–A) amplifier of hybrid laser system THL-100 was developed. The numerical investigations of spatial distribution of small-signal gain coefficient in active medium were carried out. The effect of the mirrors reflection coefficient, pumping power, and input pulse energy on the output energy was investigated. It is shown that at input pulse energy of 20 mJ and a mirror reflection coefficient of 0.995 it is possible to increase the output energy up to 3.5 J.

The ASE (Amplified Spontaneous Emission) pulses, output of the transversely excited atmosphere pumped KrF excimer laser, was compressed experimental by the way of laser oscillation quenching. The effect of mirror position and diaphragm aperture on the pulses compression is discussed in this paper. The experimental results show that, when the angle of the mirror relative to the optical axis is 3.0 mrad and the diaphragm aperture is 4.0 mm, the pulse compression effect is best, and the ideal waveform can be obtain. For the original 12.5 ns pulse, output of the discharge pumped KrF excimer laser, when using the way of laser oscillation quenching to compressed, it can be got the best results of 5.1 ns.

Spectral-luminescent and lasing properties of chromene 3 (CAS No. 52372-39-1) and chromene 13 (CAS No. 52372-36-8) in solutions and solid matrices are investigated. The regularities of their changes depended on the molecular structure and intermolecular interactions have been studied. It is shown that the fluorescence quantum yields of the studied compounds are high (0.9%). The studied compounds emit in red spectral range in solutions, films and matrices of PMMA (> 600 nm). The lasing efficiency of solid active media based on chromene 3 pumped by the second harmonic of YAG-Nd³⁺ in transverse pumping reaches 45%. Operating lifetime is comparable to the best-known organic solid state active media that emit in the red spectral range (over 30,000 pulses at one point at decreased efficiency by 5–10%). For chromene 13 lasing efficiency in solutions and matrices is lower (28% and 21%), operating lifetime of the solid active medium is high. The possibility of obtaining the generation of the compounds in thin films was studied.

Results of studying and designing an excitation pulse generator with magnetic compression of pulses by saturated choke for pumping active media of CuBr, Sr, and Ca vapor lasers are presented. A power IGBT transistor is used as a commutator. The generator makes it possible to operate at an excitation pulse repetition frequency of up to 20 kHz. The total average power at all generation lines in a CuBr laser with pumping from this generator is of about 6.0 W; in Sr and Ca lasers, of about 1.3–1.7 W.

This paper presents the algorithm for processing the images obtained by a laser monitor, which makes possible to get data on the observed object or its separate parts. The macros is designed in MATLAB environment implementing this algorithm, and its testing at different objects is carried out. It has been shown that for linear object displacement with the measurement pitch from 10 to 500 micron the error does not exceed 5 percent.

The paper repots on experimental and theoretical research in the effect of chlorine concentration on the radiation efficiency of a coaxial dielectric barrier discharge Xe–Cl ₂ excilamp at a working mixture pressure of 240–250 Torr. The experiments were performed in the range of Cl ₂ concentrations 0.01–1%. The characteristics of the barrier discharge were calculated in the framework of a one-dimensional magnetohydrodynamic model in the range of Cl ₂ concentrations 0.1–5%. It is shown that at a chlorine concentration of 0.01–0.1%, the radiation intensities of the Xe₂* band (172 nm) and XeCl* band (308 nm) are comparable. As the Cl₂ concentration in the mixture is increased, the radiation intensity of Xe₂ decreases rapidly, and at a chlorine concentration of ≥ 0.2%, the radiant flux of the discharge is dominated by the XeCl (B → X) band with a maximum intensity at 308 nm. The maximum radiation efficiency of this band is attained at chlorine concentrations of 0.4–0.5%. The numerical simulation shows that the total power deposited in the discharge increases with the chlorine concentration due to the increase in the power expended in the heating of positive and negative ions. The power dissipated by electrons decreases as the chlorine concentration in the working mixtures is increased. Recommendations are given on choosing the chlorine content in the mixture to decrease the VUV radiation intensity of the second Xe₂* excimer continuum with a little decrease in excilamp efficiency.

This work is dedicated to the urgent issue of developing a method system of integration experimental devices and software for altitudinal polarization lidar, used in investigation of the microstructure of clouds in the upper layer. The information on characteristics of the investigated medium is contained in the lidar signal, which is a pulse of a complex form with duration of several tens of microseconds.

The peculiarities of processing of the reconstructed holographic images of plankton particles are considered in the paper. The necessity of investigation of the particles appears in the challenges of hydrobiology, hydroacoustics, and oceanic optics. Method of plankton particles recognition with the accuracy up to species on example of the plankton species Episсhura Baicalensis is suggested. The results of approbation of the method are presented, based on video sequences configured from holographic data and visualizing the particles movement dynamics.

Measurement results of the chlorophyll fluorescence spectra excited by tunable radiation of first and second harmonic of Ti:Sapphire laser are presented. The efficiency of fluorescence excitation is investigated depending on laser radiation wavelength.

The technique of passive space infrared and microwave atmospheric sounding is discussed. A result of analysis of the sounding is discovery of tropospheric inner gravity waves (IGW). It is possible to investigate now the infrasonic IGW with frequency of 4 × 10^–5 Hz or less. A wave, looking like mirror of IGW, is found in the initial part of the tropopause, the wave is named mirror wave (MW). MW origin is discussed, a simulation of IGW and MW is realized. The meteorologic events, explosives and seismic activity may excite IGW and MW. Diagrams of IGW and MW during the Japan catastrophic earthquake of 2011 are shown. The before-earthquake region with large seismic activity is found.