Interferometric Laser Scanner for Direction Determination.

In this paper, we explore the potential capabilities of new laser scanning-based method for direction determination. The method for fully coherent beams is extended to the case when interference pattern is produced in the turbulent atmosphere by two partially coherent sources. The performed theoretical analysis identified the conditions under which stable pattern may form on extended paths of 0.

Resummation of divergent perturbation series: Application to the vibrational states of H2CO molecule.

Large-order Rayleigh-Schrödinger perturbation theory (RSPT) is applied to the calculation of anharmonic vibrational energy levels of H2CO molecule. We use the model of harmonic oscillators perturbed by anharmonic terms of potential energy. Since the perturbation series typically diverge due to strong couplings, we apply the algebraic approximation technique because of its effectiveness shown earlier by Goodson and Sergeev [J.

An efficient method for energy levels calculation using full symmetry and exact kinetic energy operator: tetrahedral molecules.

A simultaneous use of the full molecular symmetry and of an exact kinetic energy operator (KEO) is of key importance for accurate predictions of vibrational levels at a high energy range from a potential energy surface (PES). An efficient method that permits a fast convergence of variational calculations would allow iterative optimization of the PES parameters using experimental data. In this work, we propose such a method applied to tetrahedral AB4 molecules for which a use of high symmetry is crucial for vibrational calculations.

Does the "reef structure" at the ozone transition state towards the dissociation exist? New insight from calculations and ultrasensitive spectroscopy experiments.

Since the discovery of anomalies in ozone isotope enrichment, several fundamental issues in the dynamics linked to the shape of the potential energy surface in the transition state region have been raised. The role of the reeflike structure on the minimum energy path is an intricate question previously discussed in the context of chemical experiments. In this Letter, we bring strong arguments in favor of the absence of a submerged barrier from ultrasensitive laser spectroscopy experiments combined with accurate predictions of highly excited vibrations up to nearly 95% of the dissociation threshold.

Laser monitor for non-destructive testing of materials and processes shielded by intensive background lighting.

A single-pulse imaging laser projection system (laser monitor) is proposed for real-time monitoring high-speed processes shielded by the intensive background lighting. The brightness temperature of the lighting can reach thousands or even tens of thousands of degrees, which makes it difficult to observe the processes with the naked eye. The estimates of limiting temperatures show that the use of the proposed instrument allows to view the objects when the equivalent brightness temperature of the background lighting is up to 45,000 K.

Backscattering by hexagonal ice crystals of cirrus clouds.

Light backscattering by randomly oriented hexagonal ice crystals of cirrus clouds is considered within the framework of the physical-optics approximation. The fine angular structure of all elements of the Mueller matrix in the vicinity of the exact backward direction is first calculated and discussed. In particular, an approximate equation for the differential scattering cross section is obtained.

Backscattering reciprocity for large particles.

The backscattering reciprocity theorem is considered for large particles as compared with the incident wavelength particles of arbitrary shape. It is shown that, in the specific case of faceted particles, this theorem is provided by the appearance of pairs of conjugate backscattered beams. A parameter characterizing a deviation of any approximation from the reciprocity theorem is proposed, and it is used for estimation of reliability for the physical-optics approximation.

Backscattering Mueller matrix for quasi-horizontally oriented ice plates of cirrus clouds: application to CALIPSO signals.

A general view of the backscattering Mueller matrix for the quasi-horizontally oriented hexagonal ice crystals of cirrus clouds has been obtained in the case of tilted and scanning lidars. It is shown that the main properties of this matrix are caused by contributions from two qualitatively different components referred to the specular and corner-reflection terms. The numerical calculation of the matrix is worked out in the physical optics approximation.

Increase in laser beam resistance to random inhomogeneities of atmospheric permittivity with an optical vortex included in the beam structure.

The role of the vortical phase in the initial structure of the wave field of a laser beam propagating in the turbulent atmosphere in statistical regularities of beam wandering is studied. It is found that in the near diffraction zone the variances of wandering of the vortical beam and the fundamental Gaussian beam turns out to be identical, if the initial radius of the Gaussian beam is equal to the radius of the ring intensity distribution of the vortical beam. In the far diffraction zone, the vortical beam wanders more slightly than the Gaussian beam with the same effective radius of the initial intensity distribution does.

Remote monitoring of emission activity level from NPP using radiofrequencies 1420, 1665, 1667 MHz in real time.

The Fukushima nuclear accident showed the importance of timely monitoring and detection of radioactive emissions released from enterprises of the nuclear fuel cycle. Nuclear power plants (NPP) working continuously are a stationary source of gas-aerosol emissions which presented in a ground surface layer persistently. Following radioactive emission, untypical effects can be observed, for example: the occurrences of areas with increased ionization, and increased concentration of some gases caused by photochemical reactions.

Modeling technique of capacitive discharge pumping of metal vapor lasers for electrode capacitance optimization.

To estimate optimum gas discharge tube (GDT) electrode capacitance of metal vapor lasers (MVLs) pumped by a longitudinal capacitive discharge, we offer to use series connection of capacitors to the electrodes of a conventionally pumped GDT with inner electrodes. It has been demonstrated that the maximum output power in CuBr lasers is obtained when the capacitances of high-voltage and ground electrodes are equal. When using a model circuit an average output power reaches 12 W that suggests the possibility of generating high average output power (>10 W) in MVLs pumped using a capacitive discharge.

Beam spreading of vortex beams propagating in turbulent atmosphere.

We present some results obtained by numerical modeling of the propagation of vortex beams LG(0l) through a randomly inhomogeneous medium. The vortex beams are the lower order Laguerre-Gaussian modes. Such beams, if propagated under conditions of weak turbulence, also experience distortions, like a Gaussian beam.

Limitations of adaptive control efficiency due to singular points in the wavefront of a laser beam.

Optical vortices occur at light propagation in an inhomogeneous medium, disturbing the operation of adaptive optical systems and assuring a priori continuity of the phase fluctuation function. It is clear that the physical process of the light wave propagation has a threshold of complexity relative to the description and measurement of this process, after which the light wave contains points with zero intensity and there is no continuous wavefront. The appearance of zeros indicates the transition of phenomenon in a new condition.

Optical Scully vortex and its spatial evolution.

The structure of an optical vortex formed in a partially coherent Laguerre-Gauss laser beam was considered. The main object of study was the recorded vector field of wavefront tilts that consisted of the vortical and potential components. It was found that the vortical motion weakened as the coherence decreased.

Raman and fluorescent scattering matrix of spherical microparticles.

In this paper, we have investigated the main properties of the Raman and fluorescent matrix of scattering by microspheres using the matrix scattering formalism. The coherent and incoherent inelastic scattering of incident light by a microsphere is described by the Stokes parameters. We demonstrate the main symmetry properties of the coherent and incoherent Raman and fluorescent scattering matrices.

Detectable distance calculations for a visual navigation system using a scanning semiconductor laser with electronic pumping.

Results of detectable distance calculations for a visual navigation system based on a scanning semiconductor laser with electronic pumping (SSLEP) are presented. A semiconductor crystal in the laser is pumped with an electron beam, which is scanned across the crystal in the television-frame scan mode. The navigation system forms three orientation sectors with radiation wavelengths λ=0.

Visible and infrared extinction of atmospheric aerosol in the marine and coastal environment.

The microphysical model Marine Aerosol Extinction Profiles (MaexPro) for surface layer marine and coastal atmospheric aerosols, which is based on long-term observations of size distributions for 0.01-100 μm particles, is presented. The fundamental feature of the model is a parameterization of amplitudes and widths for aerosol modes of the aerosol size distribution function (ASDF) as functions of fetch and wind speed.

Dynamics of adaptive optical systems.

Dynamic (time) characteristics of adaptive systems are analyzed. A common adaptive system with a finite frequency band (or a finite response time) is described as a dynamic constant time-delay system, where time delay is to be much shorter than the time of coherence radius transfer through an optical beam by a mean wind speed. The questions of coherent beam formation are considered with use of the reference source.