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The theoretical, technical and technological aspects of the high energy and low angular divergence laser beam obtaining by means of Raman's scattering application in the secondary cascade are discussed. Several (2 - 6) unphased, independent, simultaneously working primary cascades were combined into one laser beam having 10 cm diameter and 10 15 - 10 16 W/cm 2 .sterad brightness at 40% summing efficiency.

The results of research on decrease in angular divergence of radiation of explosively pumped photodissociation lasers (EPPL) with the use of the method of phase conjugation for compensation of active medium optical nonuniformities and distortions of laser beam during its propagation through the atmosphere to an object of influence are presented.

The operation of laser system based on explosively pumped photodissociation lasers and designed to control the distribution of space debris not observed nowadays is described and the possibility of its breaking using laser radiation effect and its subsequent evaporation in the Earth's atmosphere is discussed.© (1998) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

The principle of operation of explosively pumped lasers and variants of its construction are described, values of parameters achieved in practice are presented.

A theoretical analysis is made of stimulated Raman scattering processes in resonators with effective angular selection of radiation. Expressions are obtained for the stimulated emission threshold and field amplitudes at pump and Stokes radiation frequencies as a function of the excess of the pumping rate over the threshold. The analysis is made for the general case of a time-modulated spatially noncoherent pump wave.

A theory is developed for modulation of the surface relief of metals, semiconductors, and insulators as a result of vaporization on exposure to laser radiation. Calculations are made of the growth increments of surface gratings as a function of the frequency, angle of incidence, and polarization of the laser radiation. It is shown that the periods and orientations of the dominant gratings depend strongly on the permittivity of the medium.

A theoretical analysis is made of the problem of parallel amplification of the Stokes signal in a nonmonochromatic spatially inhomogeneous pump field in stimulated Raman scattering. Expressions are obtained for the spatial and temporal characteristics of the process of amplification of the Stokes signal. It is shown that in the course of amplification the slowly varying amplitude of the Stokes signal field becomes similar to the slowly varying amplitude of the pump field. The relationships obtained apply also, subject to certain restrictions, to other types of scattering.

An analysis is made of the mode structure of a plane-parallel resonator with wavefront-reversing mirrors. An integral equation is derived for the oscillation modes of the resonator. It is shown that these modes are identical with those in a confocal resonator of the same length.

A theoretical analysis is made of resonators with cylindrical mirrors. Analytic expressions are obtained for the fields of the oscillation modes and the corresponding losses in unstable resonators, in the case of high equivalent Fresnel numbers. The influence of smoothing of the mirror edges on the mode losses is discussed.

A theoretical investigation is made of the characteristics of wavefront reversal in the course of a degenerate four-wave interaction in moving slow-response media. It is shown that the displacement (by a moving medium) of amplitude and phase gratings, and also diffusion of excited particles may influence greatly the parameters of a reversed wave. The characteristics of a nonlinear mechanism of light-induced heat evolution in thermodynamic-nonequilibrium media are determined for spatially inhomogeneous radiation.

Transient stimulated enthalpy scattering in inverted CO2 and stimulated Brillouin scattering in a plasma are investigated under convective instability conditions. The characteristic times for the establishment of steady-state scattering and growth increments of a Stokes wave for the transient processes are found and the relationship between these quantities and time- and coordinate-dependent parameters of the medium is established.

A theoretical analysis is made of wavefront reversal which is not sensitive to the optical quality of the nonlinear wavefront-reversing medium when complex-conjugate reference waves are formed spontaneously. An investigation is made of the linear and nonlinear stages of reversed wave generation in various nonlinear media using feedback in degenerate and nondegenerate four-wave interaction. It is shown that in nonamplifying nonlinear media this method can only be achieved by additional amplification of the radiation reflected from the nonlinear medium.

A theoretical analysis is made of the characteristics of stimulated Brillouin scattering in resonators pumped with nonmonochromatic radiation. Expressions are obtained for the threshold pump intensity and field amplitudes in a resonator. Amplitude and phase modulation of the pump field is discussed in the case of excitation of the first Stokes component in a resonator.

An analysis is made of the laws governing amplification of the Stokes wave in stimulated Raman scattering (STRS) in a dispersive medium for different models of wide-band pump radiation. An accurate solution of the STRS equations is obtained for pump radiation having a quadratically time-modulated phase. It is shown that for pump radiation for which the width of the instantaneous frequency spectrum is much less than the Raman scattering line width, the laws governing amplification of the Stokes wave differ substantially from those predicted by statistical STRS theory. Solutions of STRS equations in a dispersive medium are found for a model of temporally periodic pump radiation having a high intermode beat frequency.

The boundary-value problem is formulated for a Raman laser with a plane-parallel resonator pumped by a converging beam. The problem is formulated using the equations for the photon flux densities of the pump radiation and the first Stokes component. A method of numerical calculation on a computer is described. An approximate analytic technique is suggested for finding the transverse distributions of the Stokes photon flux density in the mirror planes. This technique can be used to find the principal features of steady-state emission from a Raman laser pumped by a converging beam. The approximate results are compared with those obtained by numerical calculations. The case of emission of two Stokes components is discussed.

It is shown that interference between the incident radiation and the resultant surface electromagnetic waves may give rise to spatially inhomogeneous heating of the surface of a medium. The subsequent spatially inhomogeneous evaporation of matter from the surface increases exponentially (on the time scale) the amplitudes of surface gratings. The periods and growth increments of such gratings are calculated as a function of the frequency, polarization, angle of incidence, and intensity of the radiation incident on a surface.

As shown, tetanus and botulin toxins had no cytotoxic effect on the 6 tested types of tissue cultures.Cl. perfringens,Cl. oedematiens,Cl. histolyticum andCl. septicum toxins produced a marked cytotoxic effect on the cultures of the HeLa strain and on the primarily trypsinized tissues of chick embryo. The use of the method of slow microcinephotography has demonstrated the specific features of the toxin action (in dynamics) of 4 causative agents of the wound anaerobic infection on tissue culture.

In repeated multiple administrations of heated B. paratyphi A vaccine certain morphological changes took place in the lymph nodes (especially regional) of guinea pigs. These consisted of rapid reduction of the total number of plasmatic cells, especially of the young forms, and of the total number of reticular cells, accompanied by a marked atrophy of reticular tissue.

A theoretical study is made of the stimulated scattering of radiation whose spectrum is much wider than the frequency of a vibrational transition in the scattering medium. It is shown that the efficiency of the scattering process then depends strongly on the statistical properties of the incident (pump) radiation.

Methods usually employed in the theory of volume holograms are used to show that the spatial distribution of the field in stimulated Brillouin scattering may be a complex conjugate of the laser radiation field. The conditions needed for experimental realization of this effect are given.

A theoretical analysis is made of the wavefront reconstruction and reversal of nonmonochromatic radiation in stimulated scattering. It is shown that several wavefront reconstruction or reversal conditions are possible for nonmonochromatic excitation. Expressions are obtained for the scattered field amplitudes. The effect of the type of time dependence of the exciting radiation on the character of the wavefront reconstruction or reversal effect is analyzed.

A theoretical study is made of the influence of diffraction by self-induced amplitude gratings on propagation of spatially inhomogeneous radiation in nonlinear resonant media. Dependences of the gain and absorption, and also of the distortion of the spatial spectrum on the parameters of the medium and radiation are determined. It is shown that interfering radiation is amplified and absorbed under saturation conditions less strongly than is spatially homogeneous radiation.

It is shown rigorously that the problem of determining the oscillation modes of ring resonators with wavefront-reversing mirrors can be reduced to the determination of the oscillation modes of a certain equivalent resonator with ordinary mirrors. Methods of determining the parameters of an equivalent resonator are described and it is established that this can be both stable and unstable. The advantages of ring resonators with wavefront-reversing mirrors are noted.

An analysis is made of the interaction between two monochromatic plane arbitrarily polarized waves traveling in parallel under stimulated Raman scattering conditions. Expressions are obtained for slowly varying vector amplitudes of the fields. It is shown that the degree of conversion of the laser radiation into the Stokes component depends strongly on the nature of the relative polarization of the fields.

A numerical solution is obtained for the problem of the steady-state oscillation in a transversely pumped Raman laser with a telescopic resonator. It is shown that the generation of the first Stokes component can be stabilized throughout the resonator. The transverse distributions of the densities of the pump and Stokes radiation fluxes are given and the quantum efficiency of the laser is calculated for different parameters. A comparison is made of the generation under single- and double-sided pumping conditions. Some analytic estimates are given of the flux densities and of the quantum efficiency. The influence of the inhomogeneity of the reflection coefficients of the mirrors on the laser action characteristics is discussed.

A solution is obtained for the equations describing stimulated Raman scattering in a dispersive medium pumped by a wide spectral line; this is done without employing the stochastic approach. It is shown that the growth increment of the amplified waves is governed by the average intensity of the pump line only if the average (over the relaxation time of the molecular vibrations of the medium) pump intensity is a steady-state quantity.

It is shown that wavefront reversal of fields may occur in interactions between fields for nonlinearities of any order. Nonlinear processes in which this effect may be observed are classified.

It was shown in comparative experiments on guinea pigs that the oral method of immunization with plague vaccine was much less effective than the inhalation and subcutaneous. Guinea pigs were found to be a poor model for studying the efficacy of oral immunization with dry live plague vaccine rehydrated before use: with the use of this preparation the animals were 46 times less resistant to aerosol plague infection than in application of strain EB cultured in agar.

Experiments were conducted in vitro. A study was made of the action of the enzymes and of the secretions of the gastrointestinal tract on the viability of the EB vaccine strain. Sensitivity of bacterial cells to the action of saliva, gastric juice, intestinal contents, trypsin, and bile proved to differ. Gastric juice inactivated the vaccine strain which expressed a satisfactory resistance towards the rest of the factors under study practically immediately. There were revealed no significant morphological changes in the cells subjected to the two-hour action of saliva, bile, trypsin and the intestinal content, by means of the electron microscopic examination. These studies permitted to substantiate the rational form of the preparation for oral administration.

Electron microscopy was applied to the study of the dynamics of endocytosis of smallpox vaccine by alveolar macrophages in intratracheal immunization of guinea pigs; 5 to 15 minutes after administration of smallpox vaccine the viruses were absorbed on the macrophage surface, penetrated into the cells by invagination and vesiculation. A possibility of adaption of smallpox virus in the alveolar macrophages 12 hours after the vaccination was confirmed documentally.

For the first time P. hamadryas were used for studying the effectiveness of oral immunization with dried live plague vaccine. Oral immunization was shown to produce morphological changes in the organs and tissues of the monkeys, which indicated the immune transformation of the organism. The challenge of the immunized animals with the infective agent introduced in aerosol showed the effectiveness of the inhalation and oral methods of immunization. P. hamadryas proved to be a suitable model for the evaluation of the effectiveness of oral vaccination. A more precise quantitative evaluation of the effectiveness of oral vaccination against plague requires further research.

An analysis is made of the problem of determination of the oscillation modes in a plane-parallel resonator with one wavefront-reversing mirror. No restrictions are imposed on the dimensions of the mirrors forming the resonator. Expressions are obtained for the fields of the oscillation modes on the mirrors. It is shown that these fields are in the form of Gaussian-Hermitian beams with parameters depending on the ratio of the transverse dimensions of the mirrors.

It is shown that wavefront reversal with a frequency shift is possible in axial anti-Stokes stimulated Raman scattering. The similarities and differences between this scheme and the phase conjugacy schemes proposed earlier are discussed. It is shown that the proposed scheme extends the class of processes in which wavefront reversal may be observed.