The Experts below are selected from a list of 300 Experts worldwide ranked by ideXlab platform
V N Lopatin - One of the best experts on this subject based on the ideXlab platform.
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Determination of spherical biological particles parameters from light-scattering Indicatrix visibility
Controlling Tissue Optical Properties: Applications in Clinical Study, 2000Co-Authors: Nickolay V Shepelevich, Inna V Prostakova, V N LopatinAbstract:The relations between intensities of light scattering in positions of Indicatrix extrema (visibility) and relative refractive index of a homogeneous sphere are studied analytically and numerically for optically soft particles. The Wentzel- Kramers-Brillouin approximation has been used for solution of inverse problem. The obtained results reveal the opportunity of determination of relative refractive index for individual spherical particles from experimental Indicatrix.© (2000) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
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basic mechanisms of formation of integral scattering Indicatrix of optically soft spherical biological particles
Advances in fluorescence sensing technology. Conference, 1999Co-Authors: Nickolay V Shepelevich, Inna V Prostakova, V N LopatinAbstract:The work is devoted to the theoretical investigation of the formation of a radiation scattered by optically soft spherical biological particles into the solid angle (Theta) o (integral Indicatrix). Integral light-scattering Indicatrix F in the range of the phase-shift parameter (Delta) from 0.01 to 80 and of the relative refractive index m (m equals n + i(chi )): n less than or equal to 1.2; (chi) less than or equal to 10-2 has been studied. Fraunhofer diffraction, geometric optics, Wentzel-Kramers-Brillouin approximation, the Mie theory have been applied for the analyses of the light- scattering Indicatrix. The theoretical and numerical investigation reveals that the integral light-scattering Indicatrix can be represented as a combination of two mechanisms, namely, Fraunhofer diffraction and geometrical optics ((Delta) greater than or equal to 3). The feasibility of determining the relative refractive index of the studied biological particles has been shown.© (1999) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
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integral Indicatrix of light scattering from open_quotes soft close_quotes spherical particles in the region of small angles
Optics and Spectroscopy, 1995Co-Authors: V N Lopatin, K A ShapovalovAbstract:The integral Indicatrix of light scattering from a {open_quotes}soft{close_quotes} spherical particle is studied as a function of the phase shift. It is shown analytically in the WKB approximation and numerically on the basis of the Mie theory and the WKB approximation that the dependence of the integral Indicatrix on the phase shift is similar to that for the factor of light scattering efficiency. Asymptotic expressions for the integral Indicatrix are obtained for large diffraction parameters in the limiting cases of small and large phase shifts in the region of small angles. 8 refs., 3 figs.
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Integral Indicatrix of light scattering from {open_quotes}soft{close_quotes} spherical particles in the region of small angles
Optics and Spectroscopy, 1995Co-Authors: V N Lopatin, K A ShapovalovAbstract:The integral Indicatrix of light scattering from a {open_quotes}soft{close_quotes} spherical particle is studied as a function of the phase shift. It is shown analytically in the WKB approximation and numerically on the basis of the Mie theory and the WKB approximation that the dependence of the integral Indicatrix on the phase shift is similar to that for the factor of light scattering efficiency. Asymptotic expressions for the integral Indicatrix are obtained for large diffraction parameters in the limiting cases of small and large phase shifts in the region of small angles. 8 refs., 3 figs.
O R Santos - One of the best experts on this subject based on the ideXlab platform.
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micellar shape anisotropy and optical Indicatrix in reentrant isotropic nematic phase transitions
Journal of Chemical Physics, 2012Co-Authors: M Simoes, A J Palangana, R Gobato, O R SantosAbstract:In this work, we will show that the concept of nematic order parameter and a generalization of the concept of optical Indicatrix, largely used in optics of anisotropic crystals, can be joined to give a new geometrical representation to the anisotropies found in lyotropic liquid crystals. Our theoretical approach will be illustrated using refractive index data of reentrant isotropic—calamitic (discotic) nematic phase transitions of potassium laurate, decanol, and heavy water mixtures.
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Micellar shape anisotropy and optical Indicatrix in reentrant isotropic—nematic phase transitions
Journal of Chemical Physics, 2012Co-Authors: M Simoes, A J Palangana, R Gobato, O R SantosAbstract:In this work, we will show that the concept of nematic order parameter and a generalization of the concept of optical Indicatrix, largely used in optics of anisotropic crystals, can be joined to give a new geometrical representation to the anisotropies found in lyotropic liquid crystals. Our theoretical approach will be illustrated using refractive index data of reentrant isotropic—calamitic (discotic) nematic phase transitions of potassium laurate, decanol, and heavy water mixtures.
R Vlokh - One of the best experts on this subject based on the ideXlab platform.
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electro optically induced topological reactions of optical Indicatrix orientation and polarization state defects
Applied Optics, 2017Co-Authors: Yu Vasylkiv, T Kryvyy, I Skab, R VlokhAbstract:We have studied the behavior of topological defects (TDs) of the optical Indicatrix orientation and polarization state, which appear when a divergent optical beam propagates through LiNbO3 crystals under an external electric field. We have found that the topological reaction of the splitting of a central TD of optical Indicatrix orientation, which occurs under the electric field EX, proceeds according to a scheme 1=1/2+1/2. This reaction splits a doubly charged optical vortex into two singly charged vortices. An increase in the electric field strength leads to angular displacement of the optical vortices, thus making it possible to operate spatial positions of the optical vortices via a Pockels effect. We have found that the lateral TDs with the strengths ±½ represent the defects of the polarization state and are not caused by defects of optical Indicatrix orientation. They form topological dipoles and generate optical vortices. These topological dipoles undergo no topological reactions in the external electric field.
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identification of the topological defects of optical Indicatrix orientation in cab4o7 glasses
Journal of Optics, 2016Co-Authors: Yu Vasylkiv, I Skab, R VlokhAbstract:We develop an experimental method for the identification of the topological defects of optical Indicatrix orientation, which appear in glass samples with residual mechanical stresses. The criteria needed to determine the sign of the strength of topological defects are formulated. The method is verified on the example of a non-annealed CaB4O7 glass sample that manifests spatially inhomogeneous residual stresses. We have found that at least seven topological defects of optical Indicatrix orientation exist under the condition when a light beam propagates through a parallelepiped-shaped glass sample. The strengths of all the defects detected by us are equal to +1/2.
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conditions of appearance of the topological defects of optical Indicatrix orientation in the glasses with residual stresses movement of the defects under application of external mechanical stress to cab4o7 glasses errata
Ukrainian Journal of Physical Optics, 2016Co-Authors: Yu Vasylkiv, T Kryvyy, I Skab, R VlokhAbstract:We have revealed experimentally a movement of the topological defects of optical Indicatrix orientation, which takes place in CaB4O7 glass with...
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topological defects of optical Indicatrix orientation associated with the edge structural dislocations in crystals
Ukrainian Journal of Physical Optics, 2015Co-Authors: V Savaryn, Yu Vasylkiv, I Skab, R VlokhAbstract:We have analyzed the effect of edge structural dislocations in solid-crystalline structures on the topology of optical Indicatrix parameters. It...
Richard J Lisle - One of the best experts on this subject based on the ideXlab platform.
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Dupin’s Indicatrix: a tool for quantifying periclinal folds on maps
Geological Magazine, 2020Co-Authors: Richard J LisleAbstract:The elliptical and hyperbolic outcrop patterns characteristic of periclinal folds can be used to classify structures according to different curvature attributes. Elliptical patterns indicate domal-basinal structures with synclastic curvature, that is, principal curvatures of the same sign. Hyperbolic patterns are diagnostic of anticlastic curvature (saddle-like structures). Such outcrop geometries are geological examples of Dupin’s Indicatrix, the geometrical figure obtained by sectioning a curved surface on a plane parallel and almost coincident with the tangent plane. The aspect ratio of Dupin’s Indicatrix is theoretically related to the ratio of the principal curvature values for the part of the structure being considered. This new method allows quantitative assessment of structures on maps and on remote sensing images. Illustrations are given from Wyoming, USA, and Yorkshire, England.
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dupin s Indicatrix a tool for quantifying periclinal folds on maps
Geological Magazine, 2003Co-Authors: Richard J LisleAbstract:The elliptical and hyperbolic outcrop patterns characteristic of periclinal folds can be used to classify structures according to different curvature attributes. Elliptical patterns indicate domal-basinal structures with synclastic curvature, that is, principal curvatures of the same sign. Hyperbolic patterns are diagnostic of anticlastic curvature (saddle-like structures). Such outcrop geometries are geological examples of Dupin’s Indicatrix, the geometrical figure obtained by sectioning a curved surface on a plane parallel and almost coincident with the tangent plane. The aspect ratio of Dupin’s Indicatrix is theoretically related to the ratio of the principal curvature values for the part of the structure being considered. This new method allows quantitative assessment of structures on maps and on remote sensing images. Illustrations are given from Wyoming, USA, and Yorkshire, England.
M Simoes - One of the best experts on this subject based on the ideXlab platform.
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micellar shape anisotropy and optical Indicatrix in reentrant isotropic nematic phase transitions
Journal of Chemical Physics, 2012Co-Authors: M Simoes, A J Palangana, R Gobato, O R SantosAbstract:In this work, we will show that the concept of nematic order parameter and a generalization of the concept of optical Indicatrix, largely used in optics of anisotropic crystals, can be joined to give a new geometrical representation to the anisotropies found in lyotropic liquid crystals. Our theoretical approach will be illustrated using refractive index data of reentrant isotropic—calamitic (discotic) nematic phase transitions of potassium laurate, decanol, and heavy water mixtures.
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Micellar shape anisotropy and optical Indicatrix in reentrant isotropic—nematic phase transitions
Journal of Chemical Physics, 2012Co-Authors: M Simoes, A J Palangana, R Gobato, O R SantosAbstract:In this work, we will show that the concept of nematic order parameter and a generalization of the concept of optical Indicatrix, largely used in optics of anisotropic crystals, can be joined to give a new geometrical representation to the anisotropies found in lyotropic liquid crystals. Our theoretical approach will be illustrated using refractive index data of reentrant isotropic—calamitic (discotic) nematic phase transitions of potassium laurate, decanol, and heavy water mixtures.
