X,T-Phase Diagram of the <$Ebold { roman {Cu sub 6 PS sub 5 J} sub x roman Br sub {(1~-~x) } }> Mixed Crystals. Optical, Dilatation and Ultrasonic Velocity Studies. - ISSN 1609-1833

On the basis of studies of the domain structure and the temperature dependences of thermal expansion and the ultrasonic velocity, the x,T-phase diagram of <$Eroman {Cu sub 6 PS sub 5 I} sub x roman Br sub {1~-~x }> mixed crystals is obtained. It is shown that all the compounds possess the first-order superionic (SI) phase transitions (PTs). Their temperatures are determined with the aid of thermal expansion measurements. The mixed crystals with the concentration <$Ex~=~0~ symbol Ш ~1> possess the second-order structural PTs into a ferroelectric-ferroelastic (FF) phase. In the composition range <$Ex~=~0~ symbol Ш ~0,75>, the temperature of the structural PT slowly decreases and the line of <$ET sub C> crosses the line of <$ET sub S> approximately at x = 0,75 (at heating) and at x = 0,9 (at cooling). Due to a wide temperature hysteresis of <$ET sub S> in therange of <$EDELTA x~=~0,75~-~0,9>, the sequence of PTs should depend on the particular temperature scan process - cooling or heating. In this range of the composition the polycritical point exists, in which the crossed curves of PTs separate the following phases: paraelectric-paraelastic-SI (the symmetry <$E{43} bar m>), paraelectric-paraelastic-nonSI (<$E{43} bar m>), ferroelectric-ferroelastic-SI (m) and ferroelectric-ferroelastic-nonSI (m). The coordinates of the polycritical point are determined as (x;T) = (0,76; 217 K).

Analysis of Singularity Properties of the Radiation Field in Low-Mode Optical Fibres. - ISSN 1609-1833

We analyze the physical processes in optical fibres on the basis of the radiation field emitted from the output end. It is demonstrated that one can judge about the excitation coefficients of the guided modes in ideal optical fibres from the position of singularity point and equal intensity lines. We have obtained dependence of the excitation coefficients of guided optical vortices (OV) upon the displacement of the OV incident on the input fibre end. It is shown that the motion of the singularity point at the output end is caused by the rotational Doppler effect.

Angular Momentum of Electromagnetic Field in Areas of Polarization Singularities. - ISSN 1609-1833

It is shown that physical manifestations of any optical singularity are, in one way or another, related to a specific temporal behaviour of the field, no matter scalar or vector cases are realized. Polarization singularities of the vector field are associated with a presence or absence of angular momentum of electromagnetic field. In the vicinity of C - point the orbital angular momentum is observed if the sings of topological charge of the vibration phase and the handedness factor are different.

Vortex Solitons, Soliton Clusters, and Vortex Lattices. - ISSN 1609-1833

We introduce novel types of self-trapped extended optical structures, which can be generated in both self-focusing and self-defocusing nonlinear media in the form of two-dimensional vortex lattices. We discuss a link of these novel objects with other types of spatially localised self-trapped states, such as vortex solitons and ring-shaped rotating clusters of solitons.

Thermal Expansion and Phase Transformation Observation in <$Eroman bold {Cs sub 2 BX sub 4 }> (B = Hg, Cd; X = Br, Cl) Crystals. 2. <$Eroman bold {Cs sub 2 HgBr sub 4 }> and <$Eroman bold {Cs sub 2 CdBr sub 4 }> crystals=Дослідження термічного розширення та спостереження фазових переходів в кристалах: <$Eroman bold {Cs sub 2 BX sub 4 }> (B = Hg, Cd; X = Br, Cl). 2. <$Eroman bold {Cs sub 2 HgBr sub 4 }> та <$Eroman bold {Cs sub 2 CdBr sub 4 }>. - ISSN 1609-1833

Photoelastic and acoustooptic (AO) parameters of <$Eroman {Cs sub 2 HgBr sub 4 }> and <$Eroman {Cs sub 2 CdBr sub 4 }> crystals are determined on the basis of studies for thermal expansion and optical indicatrix rotation at the ferroelastic (Fel) phase transition (PT) and the direct piezooptic measurements. It is shown that <$Eroman {Cs sub 2 HgBr sub 4 }> and <$Eroman {Cs sub 2 CdBr sub 4 }> crystals are good AO materials. Their photoelastic coefficients achieve respectively the values of <$Ep sub 44 ~=~0,12> and <$Ep sub 44 ~=~0,2>, while the AO figures of merit are <$EM sub 2 ~=~126,5~ times ~10 sup -15 ~ roman {s sup 3 "/"kg}> for <$Eroman {Cs sub 2 HgBr sub 4 }> and <$EM sub 2 ~=~366,9~ times ~10 sup -15 ~ roman {s sup 3 "/"kg}> for <$Eroman {Cs sub 2 CdBr sub 4 }> crystals. From the obtained results it follows that, in both <$Eroman {Cs sub 2 HgBr sub 4 }> and <$Eroman {Cs sub 2 CdBr sub 4 }>, the PT to the Fel phase 2/m is a first-order improper one, whereas the PT into the triclinic phase is of a second order. The orientations of domain walls in the Fel phase and the phase boundary between the incommensurate and Fel phases are determined.

Thermal Expansion and Phase Transformation Observation in <$Eroman bold {Cs sub 2 BX sub 4 }> (B = Hg, Cd; X = Br, Cl) Crystals=Дослідження термічного розширення та спостереження фазових перетворень у кристалах <$Eroman bold {Cs sub 2 BX sub 4 }> (B = Hg, Cd; X = Br, Cl). - ISSN 1609-1833

On the basis of the literature data and the results of our studies for the heterophase structure, domain structure, phase boundary and Raman scattering the phase diagram common for <$Eroman {Cs sub 2 HgCl sub 4 ,~Cs sub 2 HgBr sub 4 }> and <$Eroman {Cs sub 2 CdBr sub 4 }> is constructed.

Thermally Stimulated Luminescence of Radiation-Induced Defects in the Glasses of <$Eroman bold {CaO~-~Ga sub 2 O sub 3 ~-~GeO sub 2 }> System. - ISSN 1609-1833

Thermally stimulated luminescence (TSL) and electron spin resonance (ESR) spectra of X-, <$Egamma>- and <$Ebeta>-irradiated glasses with garnet (<$Eroman {Ca sub 3 Ga sub 2 Ge sub 3 O sub 12 }>), Ca-gallogermanate (<$Eroman {Ca sub 3 Ga sub 2 Ge sub 4 O sub 14 }>) and <$Eroman {Ca sub 3 Ga sub 2 O sub 6 }> compositions have been investigated and analysed. X- and <$Egamma>-irradiation of the Ge-containing glasses induces simultaneously electron and hole paramagnetic defects, stable at room temperature, whereas the same irradiation of glasses with <$Eroman {Ca sub 3 Ga sub 2 O sub 6 }> composition yields only in stable hole paramagnetic defects. The electron defects are assigned to ensembles of <$Eroman E prime> (Ge) centres with different local environments. The hole defects belong to ensembles of <$Eroman O sup -> centres, localised at different non-bridging oxygens of the glass network. The pronounced TSL glow curves in the <$Egamma>- and X-irradiated Ge-containing glasses peaked at about <$E280~ symbol Р roman C> are attributed to recombination of the <$Eroman E prime> (Ge) centres. The TSL glow curves with the maximum near <$E230~ symbol Р roman C> in the <$Egamma>- and X-irradiated Ge-containing glasses and the glass and ceramics with <$Eroman {Ca sub 3 Ga sub 2 O sub 6 }> composition are related to recombination of the <$Eroman O sup -> centres. The TSL glow curve peaked in the vicinity of <$E380~ symbol Р roman C> observed in the <$Egamma>- and X-irradiated glasses with <$Eroman {Ca sub 3 Ga sub 2 O sub 6 }> composition could be assigned to recombination of non-paramagnetic defects.

No TSL glow curves are observed in the <$Ebeta>-irradiated Ge-containing glasses, whereas the TSL glow curves with the maxima at about 120, 220 and <$E380~ symbol Р roman C> are peculiar for the glass and ceramics with <$Eroman {Ca sub 3 Ga sub 2 O sub 6 }> composition. The activation energy for the <$Ebeta>-induced defects isestimated and their models are discussed.

Application of Small-Angular Magnetooptic Polarimetry for Study of Magnetogyration in <$Eroman bold {(Ga sub 0,3 In sub 0,7 ) sub 2 Se sub 3 }> and <$Eroman bold {SiO sub 2 }> Crystals. - ISSN 1609-1833

We present the results of studies for magnetogyration (MG) effect in <$Eroman {(Ga sub 0,3 In 0,7 ) sub 2 Se sub 3 }> and <$Eroman SiO sub 2> crystals performed with the small-angular polarimetric mapping technique. It is shown that the MG effect magnitude is comparable with the experimental error.

Effect of Nonlinear Exciton-Phonon Interaction on the Intrinsic Optical Bistability in Layered Semiconductors. - ISSN 1609-1833

Theoretical investigation of the role of bending waves in the conditions for observing optical bistability in layered semiconductors is performed using the Green function method. By the example of 2H-polytype of <$Eroman PbI sub 2>, we show that efficient exciton scattering by the oscillations of this type leads to a short-wave shift of the frequency region of optical bistability, decrease in the size of this region, widening of temperature interval of its observation, a shift of the hysteresis loop towards higher intensities and a decrease in its height and width.

Electrically and magnetically induced optical rotation in <$Eroman bold {Pb sub 5 Ge sub 3 O sub 11 :Cr}> crystals at the phase transition. 1. Electrogyration effect in <$Eroman bold {Pb sub 5 Ge sub 3 O sub 11 :Cr}>. - ISSN 1609-1833

We present the results of studies for temperature dependences of electrogyration (EG) effect and natural optical activity in <$Eroman {Pb sub 5 Ge sub 3 O sub 11 :Cr}> crystals. Extremely high magnitude of EG coefficient is found for these crystals. We also demonstrate how the Curie-Weiss constant, the critical exponents of the order parameter and the dielectric permittivity, as well as the coefficients of thermodynamic potential, could be derived from the temperature dependences of optical activity and EG coefficient.

Electrically and magnetically induced optical rotation in <$Eroman bold {Pb sub 5 Ge sub 3 O sub 11 :Cr}> crystals at the phase transition. 2.Faraday effect in pure and Cr-doped lead germanate in the presence of electric field and spontaneous polarization. - ISSN 1609-1833

This work presents the results for the Faraday rotation in pure and Cr-doped lead germanate crystals studied in the course of proper ferroelectric phase transition. We show that the increment of the Faraday rotation appearing at the phase transition is caused by a combined magneto-electrooptic effect induced by spontaneous polarization. It is proportional to the square of spontaneous polarization. The phenomenon revealed by us corresponds to combined effects of crystal optics, which appear due to common action of different fields.

Dipole glassy state evidence for <$Ebold {{ roman СuInP sub 2 (Se} sub х { roman S} sub {1~-~х } ) sub 6 }> ferrielectric mixed crystals from Raman scattering and optical absorption data. - ISSN 1609-1833

The temperature and concentration dependences of Raman scattering and optical absorption spectra for <$E{ roman СuInP sub 2 (Se} sub х { roman S} sub {1~-~х } ) sub 6 > crystals are investigated. Similarly to dynamic disordering of <$Eroman Cu sup +> ions at the transition from ferrielectric into paraelectric phase for <$Eroman {CuInP sub 2 S sub 6 }> compound, static disordering of these ions in the mixed crystals in the dipole glassy state at low temperatures determines rise in the phonon damping and increase in the energetic width w of exponential optical absorption edge. The concentration and temperature dependences w(T,x) clearly reveal "asymmetry" of the dipole ordering on T - x phase diagram: the dipole glassy state smoothly evolves into ferrielectric one, coexisting with the latter under decrease of selenium content till x = 0. The dipole glassy state sharply transforms into ferrielectric phase with growing selenium concentration, passing through the relaxor state in the region of <$Ex~ symbol Ы ~0,7~-~0,8>.

Comment on "Effective Refractive Index Tensor for Weak-Field Gravity" by P. Boonserm, C. Cattoen, T. Faber, M. Visser and S. Weinfurtner. - ISSN 1609-1833

P. Boonserm et. al have tried to describe some anisotropic optical effects in the gravitation field in frame of the general relativity and by introducing the so-called "effective refractive index tensor" similarly to anisotropic crystals. We suppose that this approach is inconsequent because of the following: if one develops this claim, it would be necessary to attribute the gravitation field to the properties of matter, including its electric properties, the refractive index is not a tensorial quantity and the analogy to the situation in anisotropic crystals does not lead to artificial "effective refractive index tensor" but to naturally introduced tensor of optical-frequency dielectric impermeability of matter.

Conoscopic Patterns for Optically Uniaxial Gyrotropic Crystals in the Vicinity of Isotropic Point. - ISSN 1609-1833

We have presented computer simulations of conoscopic patterns occurring in optically uniaxial gyrotropic crystals in the vicinity of isotropic point for a number of sets of crystal parameters and orientations. The appearance of special directions characterized by equalization of linear and circular birefringences has been revealed.

Correlation- and singular-optical approaches in diagnostics of polarization inhomogeneity of coherent optical fields from biological tissues. - ISSN 1609-1833

The paper presents results related to the correlation structure of polarization images of biological tissues. The technique for measuring coordinate distribution of the degree of mutual polarization has been proposed. The topological (singular) description of polarization-inhomogeneous images of biological tissues has been analyzed. It has been shown that the average statistical size of the S-contour correlates with the half-width of autocorrelation function for the coordinate distribution of the mutual polarization degree.

Statistical Structure of Polarization-Inhomogeneous Images of Biotissues with Different Morphological Structures. - ISSN 1609-1833

We investigate statistical polarization structure of the images of biological tissues with different morphological structures. The results for polarization coordinate mapping and the statistics of first-to-fourth orders performed for the polarization azimuth and ellipticity characterising biological tissues are outlined.

Structural Phase Transition in Lysozyme Single Crystals. - ISSN 1609-1833

Polarization microscopy observations of the lysozyme single crystals in the <$E4~ symbol Р roman {C~-~40~ symbol Р C}> region are represented. The interference colours of the crystal texture observed between crossed polarizers drastically change at <$Eroman {T sub C ~=~11~ symbol Р C}> unambiguously displaying a phase transition. The temperature dependence of the birefringence deduced from these observations indicates that the phase transition is of strongly first order. The low-temperature (<$Eroman {T~<<~11~ symbol Р C}>) phase intensively scatters light. The phase transition is accompanied by the deformation (about 5 %) of the crystal. The observed textural changes are reversible in temperature. We argue that the phase transition is of a ferroelastic type and the low-temperature (<$Eroman {T~<<~11~ symbol Р C}>) phase might be of a ferroelastic type with symmetry 222 or one of two ferroelectric-ferroelastic types of symmetries 2 or 1.

Studies of Optical Damage in Photorefractive Single <$Eroman bold {LiNbO sub 3 }> Crystals using Imaging Polarimetry. - ISSN 1609-1833

The optical damage of photorefractive material, single <$Eroman LiNbO sub 3> crystal, is experimentally studied. The specimen has been illuminated with the radiation of continuous Ar-laser (the wavelength of 488 nm) focused to <$E35~ mu roman m> spot. The induced birefringence map is obtained by means of imaging polarimeter. Promising resources of the experimental setup for detecting laser-induced damage in photorefractive materials is demonstrated.

Statistical structure of 2D Stokes parameters of birefringent biotissues images. - ISSN 1609-1833

The correlation structure of 2D Stokes parameters for physiologically normal and pathologically changed biotissues is studied. The set of diagnostically urgent interconnections between the physiological state of the biotissue and the statistical moments of 2D Stokes parameters is found.

Spectroscopic Study of Haemoglobin Ligand Forms and Erythrocyte Membrane Dynamics at Alcohol Intoxication of White Rats. - ISSN 1609-1833

The results of spectroscopic studies are presented for desoxy-, oxy-, carboxy-, sulf- and methhaemoglobins of white rats and their posterity under the conditions of a durable (1 to 6 months) alcohol intoxication. The changes in the dynamics of oxy- and methhaemoglobin are found for the animals having consumed 15 %-ethanol during 1 - 4 months. It is also found that structural and functional properties of erythrocyte membranes have changed for the white rats that consumed ethanol during 4 - 6 months. The increased sensitivity of erythrocytes to the action of haemolytic agents is detected for the posterity of alcoholized parents. The obtained results show that alcohol intoxication influences not only the structural and functional properties of periphery blood erythrocytes but also the nеmogenous system.