XeCl electro-discharge laser modeling is discussed. The pump parameters of a LC-contour excitation system are studied in XeCl laser using a Ne:Xe :HCl mixture. A computation model is developed for finding the parameters of laser. The dependence of generation energy from parameters of excitation system and mixture was determined.
The influence of gas mixing ratio on stability of quasi-steady mode of electro-discharge XeCl-lasers operation is discussed.
The simplified model for electric-discharge XeCl-laser is presented. Although there are many reports on the
models of XeCl-laser, for an analysis having clear physical sense it is useful to have a simplified kinetic model. The
model enables to calculate an electrons concentration, density of excimer XeCl* molecules and specific energy deposition
in active medium. The quasi-steady mode of discharge in XeCl-lasers is analyzed.
The not weakening interest to excilamps is bound to a possibility of reception of power impulses in the UV-field of a
spectrum with significant average power. These experimental compact models of excilamps are designed for different
applications in the field of medicine, biology, spectroscopy and so on. The lamps are executed on the basis of serial domestic
elements and blocks of own production. The lamps differ by compactness and simplicity of construction.
With the purpose of reception of energy of generation 0,2-1 J, two types of electrodischarge XeCl-laser excitation system
with was created.
The modeling procedure of XeCl-laser excitation systems is developed, allowing calculate the form of a voltage pulse on
laser electrodes and energy input in the active medium. The dependence of discharge gap resistance on time is usually
simulated by exponential empirical dependence. In this case the breakdown voltage of inter-electrode gap must be taken
from experimental data also. For each gas mixture, parameters of time dependence of discharge gap resistance and value
of inter-electrode breakdown voltage have different values. Consequently, the results, which are obtained in this manner,
have practical significance for definite gas ratio of mixture. We have developed the simple model, which takes into account
the dependence of discharge gap parameters from gas pressure and composition. The solution of Boltzmann equation
for electrons in electrical field (E/N) and calculation of kinetic processes may be carried out. In this case the effective
rate of electrons formation may be approximated as function of gas composition and (E/N). Results of one model are
compared to results of other model and experimental data.
The simplified model for electric-discharge XeCl-laser is presented. Although there are many reports on the models of XeCl-laser, for an analysis having clear physical sense it is useful to have a simplified kinetic model. The model enables to calculate an electrons concentration, density of excimer XeCl* molecules, specific energy deposition in active medium and generation energy. The quasi-steady mode of discharge in XeCl-lasers is analyzed. The influence of E/P on generation energy of quasi-steady mode of electro-discharge XeCl-lasers operation is discussed.
Structural and optical characteristics of polymer-filled nanoporous glass (PFNPG) composite was studied with holographic interferometry and atomic-force microscopy methods. A high homogeneity of the bulk PFNPG samples and their surfaces has been found. Light scattering in the samples was investigated. Rather low scattering losses have been observed in spite of heterogeneous structure of the composite. This result is discussed on a base of the Rayleigh scattering model. Lasing properties including a pump-to-laser conversion efficiency and a life time due to photodestruction of PFNPG samples activated with pyrromethene dyes are reported.
The original excitation system of electro-discharge laser is considered. The excitation system represents the LC-invertor on basis of artificial storage lines. Results of computer calculation of excitation system working characteristics are discussed. An advantage of this system is the possibility of time dependence control of energy input in discharge. These results are compared with experimental data.
The dependence of resistance of a discharge on time is discussed in this work. The linearized effective ionization coefficient near breakdown voltage is introduced. It is shown, that the time of a discharge formation depends only on the square under a curve of a dimensionless overvoltage on a discharge gap, instead of from its curve shape.
Discovery generation of new laser dyes on the basis of quinolisinocoumarin's derivatives in a spectral range 490-580 nm. It is exhibited, that the greatest generative efficiency and photodurability the availability for given compoundes in the third standing coumarin's basis of the strong electron acceptor, for example carbamyl-, benzimidozoli- and benzthiazolyl-groups, and in a standing seven - electron donor N-(CH2) 6 groups. Given quinolisinocoumarin's derivatives have high generative efficiency which exceeds known laser dyes in 2-3 times. Thus the photochemical
stability exceeds rhodamine 6G on the order.
A polymer-filled nanoporous glass composite (PFNPG) has been shown recently to be a very attractive host material for solid-state dye lasers. In particular, a high-conversion (lasing) efficiency, up to 70%, has been demonstrated for pyrromethene-family dyes impregnated to PFNPG, in a visible spectral range at 2-nd harmonic nanosecond pulse duration Nd:YAG laser excitation. For development of PFNPG-based dye lasers it is important to investigate lasing characteristics of this type matrices at various excitation (pump) wavelengths. In this context we have investigated the conversion efficiency, η, and emission spectra, fem, of phenolemine 512 (Ph 512) and pyromethene 580 (PM 580) dyes impregnated into PFNPG, at excitation wavelengths, λp, varied in a range of their main absorption bands. A microsecond pulse duration liquid solution dye laser was used in our experiments as a pump source. The conversion efficiency, η=32% and 47%, has been observed at λ=525 nm for Ph 512 and PM 580 respectively with output energy as high as 250 mJ. "Anomalous" dependencies of η and fem upon λp have been revealed for both dyes. In particular, two-frequency lasing has been observed for Ph 5 12 at λ=535 nm. Mechanism of the lasing anomalies is supposed to be related to photoinduced absorption in lasing dyes.
It has been shown that NO is released under the exposure of the aqueous solutions of S-nitrosocompounds as well as blood plasma proteins and whole blood of healthy donors to UV and visible light. In addition to NO, thyil radicals which dismutate to disulfides, are formed under anaerobic conditions. In the presence of oxygen, peroxide compounds, cysteine acids derivatives are formed apart from disulfides, and NO is mainly converted to NO2-. It is suggested that NO released under the action of UV and visible light from physiological depots induces vascular relaxation, which enhances the blood flow.
It has been shown that NO is released under the exposure of the aqueous solutions of S-nitrosocompounds as well as blood plasma proteins and whole blood of healthy donors to UV and visible light. The NO release from degrading S- nitrosocompounds was monitored both spectrophotometrically (by nitrosohemoglobin formation) and using the quenching of pyrene fluorescence by nitric oxide. In addition to NO, thyil radicals which dismutate to disulfides, were formed under anaerobic conditions. In the presence of oxygen, peroxide compounds, cysteine acid derivatives and S-nitrocompounds are formed apart from disulfides, and NO is mainly converted to NO2-. It is suggested that NO releasing under the actin of UV and visible light from physiological depots induces vascular relaxation, which enhances the blood flow.
Svetlana Ostrovtsova, Alexander Volodenkov, Alexander Maskevich, Irina Artsukevich, Slavomir Anufrik, Alexander Makarchikov, Ivan Chernikevich, Vitali Stepuro
Three enzymes differing in their structural composition were irradiated by UV lasers to study the effect of temperature, protein concentration and addition of small molecules on their sensitivity to radiation exposure. The laser-induced effects were due to the structural complexity of the protein molecules and depended on the dose applied, the wavelength and the density of irradiation. The multi-enzyme 2- oxoglutarate dehydrogenase complex was subjected to pronounced irradiation-induced changes whereas the response of the two other enzymes was less significant. Reduction of the protein levels in irradiated samples was important under the XeCl laser coercion and the effects depended on the doses applied. The laser irradiation effects are suggested to be realized by means of conformational changes in the protein molecules and intermolecular association- dissociation processes.
The wide use at present of laser radiation of low intensity in the clinics for treatment of different diseases and for the stimulation of the vital activity of organism is linked to a certain extent with the presence of corresponding laser apparatus. The special role here is attributed to the lasers that are capable of generating ultra-violet radiation of high spectrum brightness and energy effectivity. The arm of this research was creation and testing on biological objects of compact, autonomous excimer XeCl- and KrF-laser. Considering the simplicity and reliability of the laser devise, automatically preionized discharge-pumped laser of the LC-generator type can be the most advantageous candidate for practical use, since UV spark preionization automatically precedes the main discharge with the time delay determined by the excitation circuit parameters and other equipment can be eliminated. Due to using the excitation circuit of the LC-generator type the primary high voltage source of comparatively small value may be used.
Rebuilding the multipole structure of the three-level atoms in the resonant light field is investigated. The calculation of the quasi-energy spectra is based on the solution of the non- stationary Schrodinger equation. It is shown that in bichromatic pumping fields the three energy levels of the atom are split into the infinity number of quasi-levels. The investigation of the behavior of the biorganic structures and molecules in the weak and strong electromagnetic fields allows us to obtain the information about the fundamental processes and the mechanisms of the transference and the transformation of the excitement energy, the molecular organization and the structure of the reactive centers (RC). Approximately RC could be described by the model of the three-level system (TLS). In this work the TLS behavior in the bichromatic field is studied theoretically.
The influence of amplitude and phase lattices on kinetics
generated by dye lasers with distributed feedback radiation is
delimited in the present paper. It is shown that generation regime of
single impulses of 200 ps is realized when amplitude lattice plays
the major role in the feedback and in the case of little above
threshold of pumping. In the case of primary contribution to the
feedback of thermal phase lattice the nonstructural impulse of
nanosecond duration is generated.
During interaction with remote environments, the operator may benefit from the addition of force feedback to the ubiquitous visual feedback. However, the apparatus required for reactive force feedback (feedback which imposes the remote environment's motion-constraints on the user by applying joint torques) is cumbersome and expensive, especially when implemented in conjunction with high degree-offreedom precision joint motion sensing. Non-reactive, tactile feedback can provide similar information, and can be implemented at much lower cost. The purposes of this research were (1)todesign and demonstrate an inexpensive tactile feedback system, and (2) to determine the extent to which such a system could aid in the performance of a simple teleoperation task. After some experimentation with some different display technologies, and preliminary design, a vibrotactile display was chosen because of its low weight, size, and low cost. The final design consisted of two voice-coils, one each for the thumb and the index finger, which were driven by a 250 Hz variableamplitude signal produced by an analog electronics unit which was controlled by a PC. Experimental results are provided to show that the addition of the tactile display provides a small but significant improvement in manual tracking performance over the use of the visual display alone, and that the tracking task may be performed with only the tactile display. In further experiments the tactile display is compared with reactive force-feedback and is shown to confer most of the reactive display's performance improvement over tracking with only a visual display.
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