75 results on '"Optical anisotropy"'
Search Results
2. Self-assembled all-oxides three-phase vertically aligned nanocomposite thin film with multifunctionality.
- Author
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Huang, Jijie, Fang, Yuan, Lu, Ping, Lu, Juanjuan, and Wang, Haiyan
- Subjects
PULSED laser deposition ,THIN films ,MAGNETIC properties ,FERROELECTRICITY ,NANOCOMPOSITE materials - Abstract
Multi-phase vertically aligned nanocomposite (MP-VAN) thin films represent a promising avenue for achieving complex multifunctionality, exploring novel interfacial phenomena, and enabling complex metamaterial designs and exploration. In this study, a novel self-assembled all-oxides three-phase VAN system was conceptualized and fabricated utilizing pulsed laser deposition (PLD) with a single composite target. Detailed microstructural analysis reveals the presence of three distinct phases: LiNbO
3 , CeO2−x , and LiNbCe1−x Oy within the MP-VAN films. Subsequently, ferroelectric, dielectric, optical anisotropy, and magnetic properties were systematically investigated to showcase the multifunctionality inherent in these films. This work presents a pioneering approach to designing and realizing MP-VAN systems, and opens up opportunities for tailoring the complex three-dimensional (3D) physical properties and property coupling of VAN films towards diverse device applications. [ABSTRACT FROM AUTHOR]- Published
- 2024
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3. DFT Insights into Mechanical, Vibrational, Electronic, and Optical Properties of Bulk WSe2 Dichalcogenide.
- Author
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Aktar, Mahbuba, Liton, M. N. H., Sarker, M. S. I., Rahman, M. M., and Khan, M. K. R.
- Subjects
OPTOELECTRONIC devices ,OPTICAL properties ,BAND gaps ,THERMAL barrier coatings ,LATTICE constants ,PHOTOVOLTAIC cells ,ANTIREFLECTIVE coatings - Abstract
The elastic, vibrational, and electro-optical properties of WSe
2 using the first-principles approach have been explored in this study. The lattice parameters of WSe2 are consistent with the available results. The structural stability of WSe2 has been proven by satisfying the stability conditions and from the phonon dispersion spectra. According to the elastic constants and moduli, WSe2 is a material with a high level of machinability, rather soft, mechanically and elastically anisotropic, and brittle in nature. The relatively lower values of the thermodynamic parameters suggest that WSe2 could be an excellent option as a thermal barrier coating (TBC) material. The overlap of the acoustic and optical modes of phonons in the lower frequency region is responsible for the enhancement of the anharmonicity of the crystal and hence reduces the thermal conductivity. WSe2 is an indirect band gap material with band gap values 0.88 (LDA) and 1.329 eV (sX-LDA) with small values of carrier effective mass. Therefore, WSe2 could be a potential candidate for electronic device applications. The optical investigation revealed that the material has a high refractive index, dielectric constant, and absorption coefficient, and considerable optical anisotropy. According to the reflectivity spectra, WSe2 could be employed as an anti-reflection coating material. By examining the optical properties, it can be noted that WSe2 is widely used to develop wave-guides, photonic devices, photovoltaic cells, and other optoelectronic devices. [ABSTRACT FROM AUTHOR]- Published
- 2024
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4. Ellipsometry Equation for the Structure Substrate–Uniaxial Anisotropic Film with the Optical Axis in the Plane of Incidence.
- Author
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Shvets, V. A., Azarov, I. A., and Spesivtsev, E. V.
- Abstract
A solution to the direct ellipsometry problem is presented for a single-layer model of an isotropic substrate–anisotropic film in the case of the orientation of the film optical axis in the plane of incidence. Analytical expressions for calculating the ellipsometric parameters of such a structure are obtained. A simple numerical algorithm is proposed for determining the ordinary () and extraordinary () refractive indices of a bulk crystal under various measurement conditions. The inverse problem of determining , , and the film thickness when changing the azimuth of the optical axis is considered. The correlation of the required parameters for such a problem is discussed. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
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5. Analysis of Dielectric Properties of Inhomogeneous Anisotropic Dye-Coated Nanoparticles.
- Author
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Sun, Cong and Li, Jiayu
- Subjects
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DIELECTRIC properties , *PERMITTIVITY , *ANISOTROPY , *NANOPARTICLES , *INHOMOGENEOUS materials , *DYES & dyeing , *SOLAR cells - Abstract
In this paper, the effective permittivity of inhomogeneous anisotropic dye-coated nanoparticles is calculated and compared using the internal homogenization method and the electric field-weighted averaging method. The relative errors of the two effective medium methods are analyzed by comparing the calculated absorption factors with those calculated by the original model. The filling factor, core size, material, and anisotropy degree of the dye molecular layer are considered, and the results showed good agreement for larger filling factor, smaller core radius, and radial dielectric constant of the shell. The highest reliability of the effective permittivity predicted by the two methods is achieved when the filling factor, core radius, and radial dielectric constant are 0.8, 15 nm, and 4, respectively. In general, the accuracy of the homogenization method within the studied wave band is higher than that of the electric field-weighted averaging method, but the electric field-weighted averaging method can be applied to anisotropic medium with arbitrary morphology, which provides a new idea for calculating the dielectric properties of inhomogeneous anisotropic medium. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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6. Influence of in-situ substrate temperature on anisotropic behaviour of glancing angle grown nickel nanocolumns.
- Author
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De, Rajnarayan, Augustine, S., Das, B., Sikdar, M. K., Ranjan, M., Sahoo, P. K., Haque, S. Maidul, Prathap, C., and Rao, K. Divakar
- Subjects
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GLANCING angle deposition , *NICKEL films , *THIN films , *MAGNETIC anisotropy , *MAGNETIC films , *SUPERCONDUCTING quantum interference devices - Abstract
In this work, we report magnetic and optical anisotropies in tilted nickel (Ni) nanocolumns and their dependencies on the film growth conditions. The Ni nanocolumns were prepared using electron beam evaporation technique in conjunction with glancing angle deposition methodology. The film depositions were performed at various in-situ substrate temperatures viz. 30 °C, 150 °C, 250 °C and 300 °C. An increase in material density with in-situ substrate temperature due to the thermal diffusion mediated coalescence of neighbouring grains was observed. The results were further corroborated with the alterations in surface morphology of the films. The modification in tilt angle of the Ni nanocolumns was also observed with in-situ substrate heating due to the non-ballistic growth approach. The presence of uniaxial optical anisotropy was established in the films deposited at low substrate temperatures (< 250 °C) using generalized ellipsometry (GE). However, the uniaxial optical anisotropy was found to be negligible for the high temperature deposited films due to thermal diffusion effect. SQUID measurements were performed for quantification of magnetic anisotropy in the films. The estimated magnetic anisotropy energy confirmed low substrate temperature deposited films to be more anisotropic as compared to others. Magnetic coercivity of the films showed film porosity dependent changes in the field values. Overall, the present investigation demonstrates anisotropic behaviour of nanocolumnar nickel thin films for non-ballistic glancing angle deposition. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
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7. Determination of the Polarization Plane Specific Rotation in Gyrotropic Crystals of the Middle Category by the Spectrophotometric Method.
- Author
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Zabelina, E. V., Shahin, R., Kozlova, N. S., and Kasimova, V. M.
- Subjects
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OPTICAL polarization , *LINEAR polarization , *CRYSTALS , *POLARIZERS (Light) , *SINGLE crystals , *RADARSAT satellites , *SPECTROPHOTOMETERS , *LIGHT intensity - Abstract
A large number of modern functional single crystals of the middle category belong to gyrotropic media. In these crystals, when light propagates along the optical axis, rotation of the plane of its polarization is observed. In this study a spectrophotometric method is used to obtain the dispersion dependences of the rotation angle of the polarization plane. This method is based on measuring the intensity of the light passing through the polarizer–crystal–analyzer system. The crystal is a polished plane-parallel plate of a uniaxial gyrotropic crystal cut perpendicularly to the optical axis. Measurements are carried out on a Cary-5000 UV-Vis-NIR spectrophotometer in the wavelength range of 200–1200 nm using polarizers Glan–Taylor prisms. Polished plane-parallel plates of known SiO2 and α-LiIO3 crystals are used as samples. The obtained dispersion dependences of the spectral transmission coefficients have an oscillating character. The discrete values of the specific angles of rotation of the plane of polarization of light are calculated from the extrema on these dependences. These discrete values can be approximated by the Drude, Chandrasekhar, and Vyshin formulas, depending on what determines the nature of the rotational ability of the plane of polarization of light in each particular material. For the studied crystals the dependences of the modified Drude formula of the form 1/ρ = f(λ2), which should have a linear character in the case of an ideal crystal, are plotted. The obtained experimental results are closely correlated to the available published data. The advantages of this method lie in its efficiency, the possibility of obtaining dispersion dependences of the specific rotation angle of the polarization plane, the need for a single sample, the possibility of assessing the nature of the rotational ability of specific crystals, and the possibility of evaluating the structural perfection of the studied crystals. [ABSTRACT FROM AUTHOR]
- Published
- 2023
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8. Extremely Short Pulses in Anisotropic Optical Media with Carbon Nanotubes Taking into Account Multiphoton Absorption.
- Author
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Konobeeva, N. N., Belibikhin, S. V., and Belonenko, M. B.
- Subjects
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MULTIPHOTON absorption , *ANISOTROPY , *ELECTROMAGNETIC wave absorption , *ELECTROMAGNETIC wave propagation , *ELECTROMAGNETIC pulses - Abstract
In this paper, we study the influence of multiphoton absorption on the propagation of electromagnetic waves in a nonlinear optical anisotropic medium with carbon nanotubes. The effective equation for the vector potential of the electromagnetic field of the pulse is obtained, taking into account the second component of the polarization of the field, as well as two- and three-photon absorption processes. The dependence of the components of the pulse field on the parameters of the problem is revealed. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
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9. Thermal, physical and biological properties of new etheric dyes with chlorine and two azo groups of anthracene.
- Author
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Moanță, Anca, Carabet, Alice Carla, Pălărie, Ion, Rotaru, Andrei, Popescu, Mariana, Leulescu, Marian, Iacobescu, Gabriela, Stoicescu, Mihail, and Rotaru, Petre
- Subjects
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ANTHRACENE , *CHLORINE , *FOURIER transform infrared spectroscopy , *QUANTUM efficiency , *ULTRAVIOLET-visible spectroscopy , *QUANTUM wells - Abstract
Three ethers with chlorine and two azo groups of anthracene, which are synthetic dyes, were prepared. The compounds were named B2ClA, B4ClA and BDClA. For these yellow compounds, called bis-azobisethers, the thermal, optical, spectral, adhesion and biological properties were investigated. The compounds are thermally stable up to about 240 °C, at higher temperatures producing, in the air, the complete oxidative decomposition, in two strongly exothermic stages, up to temperatures close to 600 °C. FTIR spectroscopy identified the components of the studied molecules, and UV-Vis spectroscopy determined the quantum efficiency of bis-azo compounds. The laser electronic fluorescence established the electronic levels between which the transitions occur when the component atoms of the molecules are excited by an Ar+ laser, as well as the energies of the quanta that accompany these transitions. Bis-azo chlorinated compounds of anthracene have optical anisotropy, proving the birefringence of their crystals. The studied compounds adhere to the glass surface, forming submicron crystallites, with the roughness of 80–100 nm. Bis-azo chlorinated compounds of anthracene interact poorly with proteins and do not show significant antioxidant properties. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
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10. Optical anisotropy assessment in nanopaper sheets by imaging Mueller matrix polarimetry.
- Author
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Hernández-López, Danay, Chicangana-Cifuentes, Jaiver, Ojeda-Morales, Yanier, Larios-López, Leticia, and Martínez-Ponce, Geminiano
- Subjects
POLARIMETRY ,MUELLER calculus ,ANISOTROPY ,CELLULOSE nanocrystals ,OPTICAL properties ,RAW materials - Abstract
Pristine nanopaper sheets have been produced by the drop-casting process using water-based cellulose nanocrystals solutions with different solute concentrations and hydrogen potential values of the solvent. In order to assess the optical properties associated to the microscopic structure of the resulting substrates, imaging Mueller matrix polarimetry was implemented. Even though the depolarizing features expected in this kind of media, optical anisotropic parameters were measured at microscopic level. It was found that spatial distribution of birefringence depends not only on the raw material nanoconformation, but also on the applied processing method. Nanopaper structural evaluation can help in understanding and optimizing optical response of sensing devices supported in these multifunctional materials. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
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11. Practice of the Visual Determination of the Direction of the Rotation of the Light Polarization Plane in Gyrotropic Uniaxial Single Crystals.
- Author
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Zabelina, E. V., Kozlova, N. S., and Svistkova, I. I.
- Subjects
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OPTICAL polarization , *SINGLE crystals , *LINEAR polarization , *POLARIZERS (Light) , *FARADAY effect , *LIGHT filters , *MONOCHROMATIC light - Abstract
When studying and applying crystals of the middle category, it is necessary to take into account the manifestations of anisotropy of their properties, in particular, optical anisotropy. One of the manifestations of optical anisotropy is the rotation of the polarization plane (gyrotropy effect), which is observed in the direction of the optical axis of such crystals. The plane of polarization of light can rotate clockwise and counterclockwise. To determine the direction of rotation of the polarization plane, simple visual methods can be used based on studies of samples in converging polarized light—observations of conoscopic figures. In general, the type of conoscopic figures depends on the relative position of the polarizers, the wavelength of light in the system, and the cut of the single crystal perpendicular to which the light propagates, as well as the thickness of the sample and the birefringence. The direction of rotation of the polarization plane can be determined by changing the type of conoscopic figure of a sample of a gyrotropic crystal cut perpendicular to the optical axis: the change in the color of the central spot during the analyzer's rotation; the extinction of the central spot when observing a conoscopic figure using light filters; the direction of movement of the rings in monochromatic light; and observation of Airy patterns. According to the experience of work in our laboratory "Single Crystals and Stock on Their Base," the observation of Airy figures is the simplest, most effective, and unambiguous visual method for determining the direction of rotation of the polarization plane. A conoscopic pattern in the form of Airy figures (a four-way spiral) occurs when a combination of two superimposed samples of gyrotropic crystals cut perpendicular to the optical axis, rotating the plane of polarization of light in opposite directions, is observed in converging polarized light. To use this method, a well-known sample of a gyrotropic crystal cut perpendicular to the optical axis is required. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
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12. Theoretical investigation of magnesium compositional variation of structural and optoelectronic properties of wurtzite MgxZn1−xSe ternary alloys through first-principle calculations.
- Author
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Sarkar, Utpal, Debbarma, Manish, Ghosh, Debankita, and Chattopadhyaya, Surya
- Subjects
- *
TERNARY alloys , *WURTZITE , *ALUMINUM-zinc alloys , *ELECTRONIC excitation , *BULK modulus , *BAND gaps , *MAGNESIUM alloys , *ALLOYS - Abstract
First-principle calculations are carried out to explore magnesium composition-dependent structural and optoelectronic features of wurtzite MgxZn1−xSe ternary alloys. Analyses show a nearly linear enhancement in lattice constants (a0, c0) but a reasonably nonlinear reduction in bulk modulus (B0) with increasing Mg composition. Successive incorporation of Mg atom(s) in place of Zn in the w-ZnSe crystal results in three direct-band gap (Γ–Γ) semiconductor ternary alloys. The fundamental band gap shows fairly nonlinear enhancement with increasing Mg composition. Each of the considered wurtzite specimens is optically anisotropic. The computed components of the refractive index give uniaxial birefringence. Peaks in the dielectric function spectrum of all the specimens in the ultraviolet (UV) region are contributed exclusively or collectively by Se-4p to Mg-4s, 3p and Zn-5s, 4p electronic excitations. With the enhancement in the fundamental band gap, static optical constants ε1(0), n(0) and R(0) of the specimens reduce, while critical point energy in their ε2(ω), k(ω), σ(ω), α(ω) spectra enhances. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
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13. Optical and electronic anisotropy of a 2D semiconductor SiP.
- Author
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Hou, Shijun, Guo, Zhengfeng, Xiong, Tao, Wang, Xingang, Yang, Juehan, Liu, Yue-Yang, Niu, Zhi-Chuan, Liu, Shiyuan, Liu, Bing, Zhai, Shenqiang, Gu, Honggang, and Wei, Zhongming
- Abstract
Two-dimensional anisotropic materials have been widely concerned by researchers because of their great application potential in the field of polarized detector devices and optical elements, which is a very important and popular research direction at present. As a IV–V two-dimensional material, silicon phosphide (SiP) has obvious in-plane anisotropy and exhibits excellent optical and electrical anisotropy properties. Herein, the optical anisotropy of SiP is studied by spectrometric ellipsometry measurements and polarization-resolved optical microscopy, and its electrical anisotropy is tested by SiP-based field-effect transistor. In addition, the normal and anisotropic photoelectric performance of SiP is shown by fabricating a photodetector and measuring it. In various measurements, SiP exhibits obvious anisotropy and good photoelectric performance. This work provides basic optical, electrical, and photoelectric performance information of SiP, and lays a foundation for further study of SiP and applications of SiP-based devices. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
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14. On the Magnetooptics of Cholesteric Liquid Crystals.
- Author
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Gevorgyan, A. H. and Golik, S. S.
- Subjects
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CHOLESTERIC liquid crystals , *MAGNETOOPTICS , *LIGHT transmission , *BOUNDARY value problems , *OPTICAL properties , *MAGNETIC fields - Abstract
Specific features of the optical properties of cholesteric liquid crystals (CLCs) in an external static magnetic field have been studied theoretically taking into account the magneto-optical activity. The boundary-value problem of reflection from a half-space of a planar CLC and light transmission through a finite layer of a magnetoactive CLC at normal incidence have been considered. Specific features of evolution of reflection from a half-space at a change in the magneto-optical activity parameter have been investigated. Existence of the effect of magnetically induced transmission (MIT) in a CLC with real parameters is shown. Specific features of the resonant MIT lines at different values of local optical anisotropy of a CLC have been discussed. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
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15. Optical emission enhancement of bent InSe thin films.
- Author
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Xie, Jiahao and Zhang, Lijun
- Abstract
In contrast to the majority of two-dimensional semiconductors such as transition metal dichalcogenides, indium selenide (InSe) possesses an intrinsic large out-of-plane oriented band-edge luminescent dipole. This unique anisotropic feature of band-edge optical emissions can be exploited to achieve enhanced optical signal in bent regions of materials created by geometrical modification. We herein investigate based on first-principle calculations the mechanism of this optical emission enhancement by modelling the photoluminescence processes in bent and flat regions of the InSe thin film. We propose in our model that the shorter-wavelength interband transition, labelled as transition B′, between the second-highest valence band and the bottom of conduction band plays an important role in the enhancing process. Our model robustly describes the dependence of optical emission enhancement in the bent InSe thin films on thickness, incident light orientation, and excitation photon energy. In particular, we found that when excitation photon energy is lower than the energy of transition B′, strong enhancement up to hundreds of times can be obtained by applying an incident light at an angle less than 70° to the InSe layers. Our results provide useful references for modulating luminescent properties of InSe films toward flexible optoelectronic device applications. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
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16. Simulation of Brightness Fields of Solar Radiation in the Presence of Optically Anisotropic Ice-Crystal Clouds: Algorithm and Test Results.
- Author
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Zhuravleva, T. B.
- Abstract
An original algorithm of statistical simulation of the solar radiative transfer in the presence of ice-crystal clouds, optically anisotropic with respect to the zenith angle of incident radiation, is presented. Examples of preliminarily calculated local optical characteristics of clouds composed of horizontally oriented plates (without accounting for the internal absorption) are given. The software developed was tested within two numerical experiments. The first experiment compared the calculations of reflected radiation for an isotropic medium using the algorithm developed earlier for clouds composed of chaotically oriented particles, and the algorithm presented in this work. The second experiment compared the angular dependence of upward radiation and the scattering phase function in ice-crystal clouds composed of horizontally oriented plates. The numerical experiments indicate that, when this algorithm is used in the radiative transfer simulation, the properties of an optically anisotropic medium are taken adequately into account. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
17. Differential Mueller matrix imaging of partially depolarizing optically anisotropic biological tissues.
- Author
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Trifonyuk, L., Sdobnov, A., Baranowski, W., Ushenko, V., Olar, O., Dubolazov, A., Pidkamin, L., Sidor, M., Vanchuliak, O., Motrich, A., Gorsky, M., and Meglinski, I.
- Subjects
- *
MUELLER calculus , *TISSUES , *GENE mapping , *METAPLASIA , *INFLAMMATION , *BRAIN , *STATISTICS , *MICROSCOPY , *ARTHRITIS Impact Measurement Scales , *DIAGNOSTIC imaging , *RESEARCH funding - Abstract
Since recently, a number of innovative polarization-based optical imaging modalities have been introduced and extensively used in various biomedical applications, with an ultimate aim to attain the practical tool for the optical biopsy and functional characterization of biological tissues. The techniques utilize polarization properties of light and Mueller matrix mapping of microscopic images of histological sections of biological tissues or polycrystalline films of biological fluids. The main drawback of currently developed laser polarimetry approaches and Mueller matrix mapping techniques is poor reproducibility of experimental data. This is due to azimuthal dependence of polarization and ellipticity values of most matrix elements to sample orientation in respect to incidence light polarization. Current study aims to generalize the methods of laser polarimetry for diagnosis of partially depolarizing optically anisotropic biological tissues. A method of differential Mueller matrix mapping for reconstruction of linear and circular birefringence and dichroism parameter distributions of partially depolarizing layers of biological tissues of different morphological structure is introduced and practically implemented. The coordinate distributions of the value of the first-order differential matrix elements of histological sections of brain tissue with spatially structured, optically anisotropic fibrillar network, as well as of parenchymatous tissue of the rectum wall with an "islet" polycrystalline structure are determined. Within the statistical analysis of polarization reproduced distributions of the averaged parameters of phase and amplitude anisotropy, the significant sensitivity of the statistical moments of the third and fourth orders to changes in the polycrystalline structure of partially depolarizing layers of biological tissue is observed. The differentiation of female reproductive sphere connective tissue is realized with excellent accuracy. The differential Mueller matrix mapping method for reconstruction of distributions of linear and circular birefringence and dichroism parameters of partially depolarizing layers of biological tissues of different morphological structures is proposed and substantiated. Differential diagnostics of changes in the phase (good balanced accuracy) and amplitude (excellent balanced accuracy) of the anisotropy of the partially depolarizing layers of the vagina wall tissue with prolapse of the genitals is realized. The maximum diagnostic efficiency of the first-order differential matrix method was demonstrated in comparison with the traditional methods of polarization and Mueller matrix mapping of histological sections of light-scattering biological tissues. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
18. Strain Engineering on the Electronic and Optical Properties of WSSe Bilayer.
- Author
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Guo, Jian, Ke, Congming, Wu, Yaping, and Kang, Junyong
- Subjects
OPTICAL properties ,OPTICAL engineering ,ATOMIC orbitals ,ISOTROPIC properties ,ENERGY bands ,ELECTRO-optical effects - Abstract
Controllable optical properties are important for optoelectronic applications. Based on the unique properties and potential applications of two-dimensional Janus WSSe, we systematically investigate the strain-modulated electronic and optical properties of WSSe bilayer through the first-principle calculations. The preferred stacking configurations and chalcogen orders are determined by the binding energies. The bandgap of all the stable structures are found sensitive to the external stress and could be tailored from semiconductor to metallicity under appropriate compressive strains. Atomic orbital projected energy bands reveal a positive correlation between the degeneracy and the structural symmetry, which explains the bandgap evolutions. Dipole transition preference is tuned by the biaxial strain. A controllable transformation between anisotropic and isotropic optical properties is achieved under an around − 6%~− 4% critical strain. The strain controllable electronic and optical properties of the WSSe bilayer may open up an important path for exploring next-generation optoelectronic applications. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
19. Ponceau 4R azoic red dye: Thermal behavior, optical anisotropy and terahertz spectroscopy study.
- Author
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Leulescu, Marian, Iacobescu, Gabriela, Bojan, Mihaela, and Rotaru, Petre
- Subjects
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TERAHERTZ spectroscopy , *ANISOTROPY , *AZO dyes , *COLORING matter in food , *THERMAL stability , *BIREFRINGENCE - Abstract
The synthetic red azo dye Ponceau 4R is an additive with widely utilization in food processing technology. Thermal behavior of the trisodium (8Z)-7-oxo-8-[(4-sulfonatonaphthalen-1-yl)hydrazinylidene] naphthalene-1,3-disulfonate, appointed Ponceau 4R or E124, was studied. Thermal analysis measurements of Ponceau 4R revealed thermal stability until 300 °C. Ponceau 4R is an anisotropic crystalline dye that has the property of birefringence. The THz spectroscopy allowed the determination of the characteristic absorption frequencies of this colorant and its identification in any food. In the THz spectrum of Ponceau 4R, it can be seen that the strongest absorption is produced for the radiation with frequency of 1.41, 1.74 and 3.81 THz. THz spectroscopy of Ponceau 4R identified spectral "signatures" of azo food dye studied, which were obtained by the processing of the numerical data of THz spectroscopy. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
20. The Influence of Electric and Magnetic Fields on Angular Distribution of Intensity of Light Scattered from a Cold Atomic Ensemble.
- Author
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Larionov, N. V. and Sokolov, I. M.
- Subjects
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MAGNETIC fields , *LIGHT intensity , *ELECTRIC fields , *ANISOTROPY , *RADIATION , *LIGHT scattering - Abstract
An angular distribution of the intensity of light scattered from an optically dense cold atomic ensemble placed into homogeneous static electric or magnetic field is calculated. Partial contributions of different orders of scattering into the selected polarization component of total intensity of the secondary radiation are analyzed. It is demonstrated that static fields make the medium anisotropic, which results in changes in both an angular distribution of such a radiation and relative contributions of different orders of scattering. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
21. Detection of Weak Optical Anisotropy in Strontium Tetraborate Activated by Ytterbium Ions.
- Author
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Khasanov, T. Kh.
- Subjects
- *
YTTERBIUM ions , *ANISOTROPY , *YTTERBIUM , *STRONTIUM , *STRONTIUM ions , *BULK solids , *GONIOMETERS - Abstract
A technique for detecting and measuring the weak optical anisotropy has been proposed and experimentally implemented. The strontium tetraborate activated by ytterbium ions, which is considered to be an amorphous glass, has been investigated and its anisotropy comparable with the instrumental errors of ellipsometer goniometers has been found and measured. The proposed approach is based on a previously developed effective and relatively simple method, in which the contribution of the surface (transition) layer to the formation of the resulting beam is essentially smaller than the contribution of the bulk material. The relations between the ellipsometer measuring zones have been used. Some important aspects of the optical and mechanical alignment of the ellipsometers have been described as applied to the weak anisotropy investigations. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
22. Synthesis and Characterization of Oriented Silver Nanospheroids in Glass.
- Author
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Sidorov, Alexander I., Tung, Ngo Duy, Van Vu, Ngo, and Nikonorov, Nikolay V.
- Subjects
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LIGHT transmission , *SILVER , *OPTICAL spectra , *GLASS , *LIGHT absorption , *OPACITY (Optics) - Abstract
We present a simple method of oriented prolate silver nanospheroid synthesis in silicate glasses. The appearance of silver nanospheroids in glass is confirmed by the shape of plasmon resonance absorption band in optical density spectrum, by TEM-images, and by calculation. Experiments have shown that nanocomposite with oriented silver spheroids possesses optical anisotropy, including dichroism and polarization-dependent transmission of light. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
23. Estimation of the Dimensions of Nanoparticles in Multicomponent Colloidal Sysems by Dynamic Light Scattering.
- Author
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Levin, A. D., Sadagov, A. Yu., Shchelkonogov, V. A., and Sinebryukhova, A. M.
- Subjects
- *
NANOSTRUCTURED materials , *BLOOD plasma , *LIPOSOMES , *GOLD nanoparticles , *LINEAR polarization , *LIGHT scattering - Abstract
Possible applications of dynamic light scatterring for measurement of the sizes of nanoparticles and their distributions by size are considered. Nanoparticles are added to a complex colloidal system (blood plasma or some other biological fluid) containing particles of similar sizes. The contribution of the added particles to the light scattering is found by the method of depolarized dynamic light scattering (for anisotropic particles) or by processing experimental data (for isotropic particles). Examples illustrating the determination of the sizes of gold nanoparticles and liposomes added to undiluted blood plasma are presented. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
24. Optical anisotropy in micromechanically rolled carbon nanotube forest.
- Author
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Razib, Mohd, Rana, Masud, Saleh, Tanveer, Fan, Harrison, Koch, Andrew, Nojeh, Alireza, Takahata, Kenichi, and Muthalif, Asan
- Abstract
The bulk appearance of arrays of vertically aligned carbon nanotubes (VACNT arrays or CNT forests) is dark as they absorb most of the incident light. In this paper, two postprocessing techniques have been described where the CNT forest can be patterned by selective bending of the tips of the nanotubes using a rigid cylindrical tool. A tungsten tool was used to bend the vertical structure of CNTs with predefined parameters in two different ways as stated above: bending using the bottom surface of the tool (micromechanical bending (M2B)) and rolling using the side of the tool (micromechanical rolling (M2R)). The processed zone was investigated using a Field Emission Scanning Electron Microscope (FESEM) and optical setup to reveal the surface morphology and optical characteristics of the patterned CNTs on the substrate. Interestingly, the polarized optical reflection from the micromechanical rolled (M2R) sample was found to be significantly influenced by the rotation of the sample. It was observed that, if the polarization of the light is parallel to the alignment of the CNTs, the reflectance is at least 2 x higher than for the perpendicular direction. Furthermore, the reflectance varied almost linearly with good repeatability (~10%) as the processed CNT forest sample was rotated from 0° to 90°. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
- View/download PDF
25. Spectral and Polarizing Properties of Anisotropic Films Based on Polyvinyl Alcohol and 4,4′-Bis[4-(Phenylamino)-6-(Methoxy-1,3,5-Triazin-2-YL) Amino]Stilbene-2,2′-Disulfonic Acid.
- Author
-
Bondarev, S., Ariko, N., Filippovich, L., Karoza, A., and Stupak, A.
- Subjects
- *
POLYVINYL alcohol , *ANISOTROPY , *STILBENE , *SULFONIC acids , *OPTICAL polarization , *ULTRAVIOLET spectroscopy - Abstract
The spectral and polarization characteristics of optically anisotropic polyvinyl alcohol (PVA) films containing 4,4'-bis[4-(phenylamino)-6-(methoxy-1,3,5-triazin-2-yl)amino]stilbene-2,2'-disulfonic acid as dichroic dye, which has intense blue fluorescence, were investigated by polarized luminescence and absorptionspectroscopy in the IR and UV regions. With fourfold uniaxial stretching of the film the orientation parameter of the dye amounts to 0.82-0.86, the maximum polarizing ability of the film is 96% (at the maximum of the absorption band at 375 nm), and the degree of polarization and quantum yield of fluorescence at the optimum concentration of the dye amount to 0.90 and 0.91. The degree of orientation of the dye molecules depends weakly on the concentration (0.01-0.50 wt.%) and increases with increase of the uniaxial stretching of the film. The insertion of the dye molecules between the PVA chains leads to a reduction of the crystallinity of the polymeric matrix. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
26. Direct surface relief formation in nanomultilayers based on chalcogenide glasses: A review.
- Author
-
Achimova, E.
- Abstract
In this review the investigations of direct surface relief formations in nanomultilayers from chalcogenide glasses are summarized. Chalcogenide glasses are known to exhibit several photoinduced phenomena, both scalar and vectorial, which are connected with photoinduced structural transformations, defects creation, and atoms diffusion. Surface relief formation in chalcogenide glasses films has been intensively studied due to its applicability to reversibly form versatile patterns and diffractive optical elements. Both intensity and polarization holography have been employed to generate surface relief structures in chalcogenide glasses materials, including monolayers and multilayer structures. The research outlined here has not only led to better understanding of the material properties that affect the optical performance of chalcogenides structures, but also illustrated the momentum in the field that has led to the development of high-performance nanostructured devices. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
27. Electrooptical Fourier-processor for microobjects investigation.
- Author
-
Domnin, K., Velichko, E., and Aksenov, E.
- Abstract
This work is devoted to creation and research of the multichannel optical processor allowing us to carry out the diffractometric and polarimetric analysis for assessment of optiko-physical properties as biological microobjects and is exemplary optically transparent randomly inhomogeneous medium. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
28. Measurement of inhomogeneous absorptive organic media with polarization interferometric confocal microscope.
- Author
-
Fujita, Kohei and Egami, Chikara
- Subjects
- *
POLARIZATION interferometers , *CONFOCAL microscopy , *OPTICAL polarization , *CHROMOPHORES , *ELECTRIC fields - Abstract
Polarization interferometric confocal microscope has been developed for high-precision measurement, especially for inhomogeneous organic media doped with nonlinear chromophores. The microscope has a novel contrast-enhancing technique: suppressing the background electric field with polarization interferometer. With this technique, the microscope has allowed optical anisotropy detection in a submicron area (400 nm × 400 nm), even with a low-cost and low-power continuous-wave (CW) laser light source. In particular, the microscope clearly distinguishes between isotropic and anisotropic regions. According to polarization interferometric ellipsometry, the microscope produces inspection images showing planer distribution of the optical parameter directly. [ABSTRACT FROM AUTHOR]
- Published
- 2015
- Full Text
- View/download PDF
29. Differential Mueller matrix imaging of partially depolarizing optically anisotropic biological tissues
- Author
-
Trifonyuk, L. (L.), Sdobnov, A. (A.), Baranowski, W. (W.), Ushenko, V. (V.), Olar, O. (O.), Dubolazov, A. (A.), Pidkamin, L. (L.), Sidor, M. (M.), Vanchuliak, O. (O.), Motrich, A. (A.), Gorsky, M. (M.), Meglinski, I. (I.), Trifonyuk, L. (L.), Sdobnov, A. (A.), Baranowski, W. (W.), Ushenko, V. (V.), Olar, O. (O.), Dubolazov, A. (A.), Pidkamin, L. (L.), Sidor, M. (M.), Vanchuliak, O. (O.), Motrich, A. (A.), Gorsky, M. (M.), and Meglinski, I. (I.)
- Abstract
Since recently, a number of innovative polarization-based optical imaging modalities have been introduced and extensively used in various biomedical applications, with an ultimate aim to attain the practical tool for the optical biopsy and functional characterization of biological tissues. The techniques utilize polarization properties of light and Mueller matrix mapping of microscopic images of histological sections of biological tissues or polycrystalline films of biological fluids. The main drawback of currently developed laser polarimetry approaches and Mueller matrix mapping techniques is poor reproducibility of experimental data. This is due to azimuthal dependence of polarization and ellipticity values of most matrix elements to sample orientation in respect to incidence light polarization. Current study aims to generalize the methods of laser polarimetry for diagnosis of partially depolarizing optically anisotropic biological tissues. A method of differential Mueller matrix mapping for reconstruction of linear and circular birefringence and dichroism parameter distributions of partially depolarizing layers of biological tissues of different morphological structure is introduced and practically implemented. The coordinate distributions of the value of the first-order differential matrix elements of histological sections of brain tissue with spatially structured, optically anisotropic fibrillar network, as well as of parenchymatous tissue of the rectum wall with an “islet” polycrystalline structure are determined. Within the statistical analysis of polarization reproduced distributions of the averaged parameters of phase and amplitude anisotropy, the significant sensitivity of the statistical moments of the third and fourth orders to changes in the polycrystalline structure of partially depolarizing layers of biological tissue is observed. The differentiation of female reproductive sphere connective tissue is realized with excellent accuracy. The diff
- Published
- 2020
30. Effects of substrate orientation on opto-electronic properties in self-assembled InAs/GaAs quantum dots.
- Author
-
Chimalgi, Vinay, Kharche, Neerav, and Ahmed, Shaikh
- Abstract
Electronic structure and optical transition characteristics in (100), (110), and (111) oriented InAs/GaAs quantum dots (containing $${\sim }2$$ million atoms) were studied using a combination of valence force-field molecular mechanics and 20-band $$sp^{3}d^{5}s^{*}$$ atomistic tight-binding framework. These quantum dots are promising candidates for non-traditional applications such as spintronics, quantum cryptography and quantum computation, but suffer from the deleterious effects of various internal fields. Here, the dependence of strain and polarization fields on the substrate orientation is reported and discussed. It is found that, compared to the (100) and (110) oriented counterparts, quantum dots grown on the (111) oriented substrate exhibit a smaller splitting (non-degeneracy) in the excited $$P$$ states and enhanced isotropy in the interband optical emission characteristics. [ABSTRACT FROM AUTHOR]
- Published
- 2014
- Full Text
- View/download PDF
31. Conformational, optical, electro-optical, and dynamic characteristics of cross-linked poly(N-acryloyl-11-aminoundecanoic acid).
- Author
-
Tsvetkov, N., Lebedeva, E., Lezov, A., Podseval'nikova, A., Akhmadeeva, L., Mikhailova, M., Zorin, I., Makarov, I., and Bilibin, A.
- Subjects
- *
CROSSLINKED polymers , *ELECTRIC properties of polymers , *OPTICAL properties of polymers , *CHROMATOGRAPHIC analysis , *DRUG carriers , *NANOPARTICLES - Abstract
Polymerizable surfactants now attract a great interest due to high potential of their practical application as components of pseudostationary phase in micellar chromatography, drug carriers, and 'building blocks' for molecular design of nanoparticles and nanostructured polymer materials, for encapsulation of various biological preparations. In the present work, we have studied poly(N-acryloyl-11-aminoundecanoic acid) (cross-linked comb-like polymer). Cross-linked polymers were obtained via copolymerization of the surfactant bearing double bond in hydrophobic tail with hydrophobic bifunctional cross-linker in micellar solution. Of special interest was the comparison between cross-linked and non-cross-linked polymers and influence of alkaline medium on characteristics of these samples. Non-cross-linked polymers were obtained by hydrolysis of the cross-linked product (treating with NaOH). The mixture of cyclohexanol and dioxane (1:1 volume ratio) was used as a solvent. Detailed studies of the obtained polymers by viscometry, dynamic light scattering, flow birefringence, and equilibrium and non-equilibrium electric birefringence were performed. It was established that during cross-linking process, two types of bonds are formed (the ones inside individual molecules and between several polymer chains). It was shown that cross-linked macromolecular nanoparticles can be transformed into comb-like polymers. [ABSTRACT FROM AUTHOR]
- Published
- 2014
- Full Text
- View/download PDF
32. How important is nonlinear piezoelectricity in wurtzite GaN/InN/GaN quantum disk-in-nanowire LED structures?
- Author
-
Yalavarthi, Krishna, Chimalgi, Vinay, and Ahmed, Shaikh
- Subjects
- *
PIEZOELECTRICITY , *NONLINEAR systems , *WURTZITE , *GALLIUM nitride , *QUANTUM optics , *ENERGY bands - Abstract
Numerical investigation is carried out to compare the effects of linear and nonlinear piezoelectric fields on the electronic and optical properties of recently-proposed wurtzite GaN/InN/GaN quantum disk-in-wire LED structures. The computational framework employs a combination of fully atomistic valence force-field molecular mechanics and 10-band $$sp^{3}s$$ *-SO tight-binding electronic band-structure models, and accurately captures the interplay between the long-range electro-mechanical fields and the quantum atomicity in the device. In particular, to model piezoelectricity in the wurtzite lattice, four different polarization models (based on the experimental and ab initio coefficients) have been considered in increased order of accuracy. In contrast to recent studies on thin-film quantum well structures, simulation results obtained in this work show that the nonlinear (second-order) piezoelectric contribution has insignificant effects on the overall electronic and optical properties in reduced-dimensionality (nanoscale) disk-in-wire LED structures. [ABSTRACT FROM AUTHOR]
- Published
- 2014
- Full Text
- View/download PDF
33. Ultrashort pulse generation in the medium with induced optical anisotropy.
- Author
-
Hovhannisyan, M.
- Abstract
Abilities of the method of accumulation of coherent unstable response of a medium for amplification of the rotated component of the probe wave's polarization in the atomic medium of three-level atoms are studied. Probe wave is examined in frames of the perturbation theory and its frequency is considered near to one photon resonance from the ground to the first excited level. The intense monochromatic pump field connects two excited energy levels and propagates through the medium without a change. The broadening of spectral lines caused by the relaxation processes and the Doppler broadening are included into the calculations. It is shown that by multiple consistent instantaneous change of input probe field's phase from 0 to π and back, it is possible to obtain, in the tail part of the rotated component of the probe field, a separate narrowed light pulse along with the increase in intensity by more than an order of magnitude with respect to the input field. [ABSTRACT FROM AUTHOR]
- Published
- 2014
- Full Text
- View/download PDF
34. Differential Mueller matrix imaging of partially depolarizing optically anisotropic biological tissues
- Author
-
Igor Meglinski, A. V. Motrich, L. Trifonyuk, M. I. Sidor, Mykhaylo P. Gorsky, O. Vanchuliak, O. I. Olar, W. Baranowski, L. J. Pidkamin, Anton Sdobnov, V. A. Ushenko, and Alexander V. Dubolazov
- Subjects
Materials science ,Quantitative Biology::Tissues and Organs ,Statistics as Topic ,Physics::Medical Physics ,Polarimetry ,02 engineering and technology ,Dermatology ,01 natural sciences ,law.invention ,010309 optics ,020210 optoelectronics & photonics ,Optics ,Biomedical imaging ,law ,0103 physical sciences ,0202 electrical engineering, electronic engineering, information engineering ,Humans ,Mueller calculus ,Partial depolarization ,Anisotropy ,Polarized light ,Birefringence ,business.industry ,Optical Imaging ,Brain ,Dichroism ,Laser ,Polarization (waves) ,Mueller matrix ,Optical anisotropy ,Surgery ,Original Article ,Female ,Microscopy, Polarization ,business ,Matrix method - Abstract
Since recently, a number of innovative polarization-based optical imaging modalities have been introduced and extensively used in various biomedical applications, with an ultimate aim to attain the practical tool for the optical biopsy and functional characterization of biological tissues. The techniques utilize polarization properties of light and Mueller matrix mapping of microscopic images of histological sections of biological tissues or polycrystalline films of biological fluids. The main drawback of currently developed laser polarimetry approaches and Mueller matrix mapping techniques is poor reproducibility of experimental data. This is due to azimuthal dependence of polarization and ellipticity values of most matrix elements to sample orientation in respect to incidence light polarization. Current study aims to generalize the methods of laser polarimetry for diagnosis of partially depolarizing optically anisotropic biological tissues. A method of differential Mueller matrix mapping for reconstruction of linear and circular birefringence and dichroism parameter distributions of partially depolarizing layers of biological tissues of different morphological structure is introduced and practically implemented. The coordinate distributions of the value of the first-order differential matrix elements of histological sections of brain tissue with spatially structured, optically anisotropic fibrillar network, as well as of parenchymatous tissue of the rectum wall with an “islet” polycrystalline structure are determined. Within the statistical analysis of polarization reproduced distributions of the averaged parameters of phase and amplitude anisotropy, the significant sensitivity of the statistical moments of the third and fourth orders to changes in the polycrystalline structure of partially depolarizing layers of biological tissue is observed. The differentiation of female reproductive sphere connective tissue is realized with excellent accuracy. The differential Mueller matrix mapping method for reconstruction of distributions of linear and circular birefringence and dichroism parameters of partially depolarizing layers of biological tissues of different morphological structures is proposed and substantiated. Differential diagnostics of changes in the phase (good balanced accuracy) and amplitude (excellent balanced accuracy) of the anisotropy of the partially depolarizing layers of the vagina wall tissue with prolapse of the genitals is realized. The maximum diagnostic efficiency of the first-order differential matrix method was demonstrated in comparison with the traditional methods of polarization and Mueller matrix mapping of histological sections of light-scattering biological tissues.
- Published
- 2020
35. Effect of acetyl substitution on the optical anisotropy of cellulose acetate films
- Author
-
Hikaru Shimada, Shogo Nobukawa, Masayuki Yamaguchi, Misaki Kondo, and Kazuya Hatamoto
- Subjects
Diffraction ,Materials science ,Birefringence ,Optical anisotropy ,Polymers and Plastics ,Cellulose acetate ,Substitution (logic) ,Relaxation (NMR) ,Refractive index ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,chemistry.chemical_compound ,Crystallography ,Wavelength ,chemistry ,Orientation ,Dispersion (optics) ,0210 nano-technology - Abstract
The effect of acetyl substitution on the optical properties of cellulose acetate (CA) was investigated in the present study, because a strong demand for advanced retardation films increases greatly these days. The hot-stretched films with high acetyl substitution had negative orientation birefringence, whereas those with low acetyl substitution had positive orientation birefringence with extraordinary wavelength dispersion. It should be noted that orientation birefringence hardly relaxed even after cessation of hot-stretching. The slow relaxation of crystal orientation was responsible for the anomalous optical anisotropy, as confirmed by two-dimensional X-ray diffraction. Moreover, the slow relaxation of orientation birefringence would greatly benefit the preparation of CA optical retardation films by hot-stretching, because it would simplify the precise control of retardation. The stress-optical coefficient in the glassy state was also evaluated, and was found to decrease with the degree of acetyl substitution. This is an attractive property for optical film applications.
- Published
- 2018
36. Aerospace laser sensing of cloudiness: numerical statistical modeling.
- Author
-
Kargin, A., Kargin, B., and Lavrov, M.
- Subjects
- *
LASER beams , *CLOUDINESS , *MULTIPLE scattering (Physics) , *MONTE Carlo method , *STATISTICAL models - Abstract
In the numerical modeling of laser radiation transfer in optically dense cloudy media it is necessary to take into account multiple scattering effects, which alter the spatiotemporal structure of light pulses. The Monte Carlo method makes it possible to achieve the most complete account of these effects in the solution of direct problems of laser sensing of scattering media. This work considers two problems. The first is connected with construction of an adequate optical model of crystalline clouds which takes account their optical anisotropy. The second touches on questions of Monte Carlo modeling of laser radiation transfer in optically anisotropic media. A number of results of numerical experiments are presented which establish a quantitative connection between some cloud parameters and the magnitude and shape of the time convolution of a non-stationary laser return signal reflected by a single-layer continuous crystalline or liquid-droplet cloud and by two-level continuous cloudiness, when the crystalline cloud is located above the liquid-droplet cloud. [ABSTRACT FROM AUTHOR]
- Published
- 2013
- Full Text
- View/download PDF
37. Electro-optical Properties, Polarity and Chain Rigidity of Poly(dialkoxyphosphazene)s with Variable Side-Chain Length.
- Author
-
Yevlampieva, N., Tur, D., Kovshik, A., and Rjumtsev, E.
- Subjects
- *
ALIPHATIC compounds , *KERR electro-optical effect , *ANISOTROPY , *POLARIZABILITY (Electricity) , *MACROMOLECULES - Abstract
Molecular properties of poly(dialkoxyphosphazene) (PDAOP) series with the aliphatic side-chains contained 3, 4, 6, and 7 carbon atoms were investigated in dilute benzene solutions by techniques of electro-optical Kerr effect and dynamo-optical Maxwell effect, and by dielectric spectroscopy. The sign inversion of Kerr effect and Maxwell effect in PDAOP solutions from positive to negative was detected at the side-chain length range of 5-6 carbon atoms. These phenomena were explained by the strong dependence of anisotropy of optical polarizability of PDAOP monomeric unit on chemical structure and change of its sign at the indicated side-chain lengths. It was demonstrated that PDAOPs possess a critical side-chain-length interval at which their physical properties, depending on the intramolecular ordering, display a singularity. It was also shown that the studied PDAOP samples are not flexible-chain polymers. They are characterized by Kuhn segment 47-65 Å, the value of which increases with the elongation of aliphatic side-chain. Dielectric properties of PDAOP were correlated to the properties of the macromolecules with manifestation of kinetic rigidity under a treatment of electric field. [ABSTRACT FROM AUTHOR]
- Published
- 2012
- Full Text
- View/download PDF
38. Influence of the tridecane and heptadecane molecule chain length on the structural characteristics of their epitropic liquid-crystal layers.
- Author
-
Kiriyan, S., Altoiz, B., Shatagina, E., and Shatagina, A.
- Subjects
- *
ALKANES , *MOLECULAR structure , *LIQUID crystals , *ANISOTROPY , *NON-Newtonian flow (Fluid dynamics) , *SUBSTRATES (Materials science) , *PARAMETER estimation - Abstract
The optical anisotropy and viscosity of micron interlayers, bounded by metallic substrates, of two n-alkane homologs - tridecane and heptadecane - have been measured. The thickness and characteristics of the orientational ordering of epitropic liquid-crystal layers formed on the substrates have been established. The structure parameters obtained are higher for heptadecane, which is attributable to the longer length of its alkyl chain. [ABSTRACT FROM AUTHOR]
- Published
- 2012
- Full Text
- View/download PDF
39. Optical properties of SiO and ZnO nanostructured replicas of butterfly wing scales.
- Author
-
Xu, Zhe, Yu, Ke, Li, Bo, Huang, Rong, Wu, Ping, Mao, Huibing, Liao, Na, and Zhu, Ziqiang
- Abstract
SiO and ZnO inverse structure replicas have been synthesized using butterfly wings as templates. The laser diffraction performance of the SiO inverse structure replica was investigated and it was found that the zero-order light spot split into a matrix pattern when the distance between the screen and the sample was increased. This unique diffraction phenomenon is closely related to the structure of the SiO inverse structure replica. On the other hand, by analyzing the photoluminescence spectrum of the ZnO replica, optical anisotropy in the ultraviolet band was demonstrated for this material. [InlineMediaObject not available: see fulltext.] [ABSTRACT FROM AUTHOR]
- Published
- 2011
- Full Text
- View/download PDF
40. Molecular orientation and optical anisotropy in drawn films of cellulose diacetate- graft-PLLA: comparative investigation with poly(vinyl acetate- co-vinyl alcohol)- graft-PLLA.
- Author
-
Unohara, Takeshi, Teramoto, Yoshikuni, and Nishio, Yoshiyuki
- Subjects
CELLULOSE ,ANISOTROPY ,COPOLYMERS ,COMPARATIVE studies ,PHYSICAL & theoretical chemistry - Abstract
Cellulose diacetate- graft-poly(L-lactide) (CDA- g-PLLA) and poly(vinyl acetate- co-vinyl alcohol)- graft-PLLA (P(VAc- co-VOH)- g-PLLA) were synthesized over a range of compositions, by ring-opening copolymerization of L-lactide at the original hydroxyl positions of the respective trunk polymers, CDA (acetyl DS = 2.15) and P(VAc- co-VOH)- g-PLLA (VAc = 64.2 mol%). All the products of both graft copolymer series were non-crystallizable and their solution-cast films showed no domain segregation of the two components that constituted the trunk and side-chains. A comparative study on the molecular orientation and optical anisotropy induced by uniaxial stretching of film samples was undertaken for the two copolymer series with various side-chain lengths. Overall behaviour of the orientation was estimated from the statistical second (
) and fourth ( ) moments obtained by a fluorescence polarization method using a rod-like probe of ~2.5 nm. Upon stretching, any film of both series imparted a positive orientation function, i.e., f = (3 − 1)/2 > 0, which increased with the extent of deformation. The degree of molecular orientation was higher in the CDA-graft series with a semi-rigid trunk, and, in both series, it declined monotonically with increasing content of the PLLA side-chain. With regard to the optical anisotropy, CDA- g-PLLA films always exhibited a positive birefringence (Δ n > 0) upon stretching, while drawn films of P(VAc- co-VOH)- g-PLLA displayed a negative one. This contrast in polarity reflects a difference in the intrinsic birefringence between the two trunk polymers. Of interest was the finding of a discontinuous change in Δn value with copolymer composition (PLLA content) for the respective graft series, when compared at a given stage of elongation of the films. Discussion took into consideration the locally different orientation manners of the attached PLLA chain segments. [ABSTRACT FROM AUTHOR] - Published
- 2011
- Full Text
- View/download PDF
41. The rheology of motor oils with quasi-liquid crystalline layers in a tribotriad.
- Author
-
Kiriyan, S. and Altoiz, B.
- Abstract
Optical anisotropy and elevated viscosity are observed experimintally in the micron interlayers of motor oils in respect to the value and volume. These features are attributed to the structural inhomogeneity of the interlayers, namely to the organization of the subsurface epitropic liquid crystalline layers on the substrates bounding the interlayer. Such interlayers are studied in a model tribotriad with optical and rheological methods. The layer value of double refraction and thickness are assessed when the latter declines with increasing shear flow rate. The role of such additives as the surfactants is analyzed because they favor organization of the structured layer. [ABSTRACT FROM AUTHOR]
- Published
- 2010
- Full Text
- View/download PDF
42. Effects of the nature of counterions in solution on interactions of phenoxazones, xanthones, and carbazoles containing benzo-crown groups with DNA.
- Author
-
Moroshkina, E. B., Bogdanov, A. A., Kolonistova, M. O., Sedova, O. B., and Urusova, T. A.
- Subjects
- *
DNA , *XANTHONE , *CARBAZOLE , *RADICALS , *CIRCULAR dichroism , *PROPERTIES of matter , *GLYCINE - Abstract
The interactions of DNA with phenoxazones, xanthones, and carbazoles containing the (benzo-18-crown-6)-4′-yl and (benzo-15-crown-5)-4′-yl radicals bonded to the chromophore via spacers of different lengths in the presence of Na+ and K+ ions were studied by spectrophotometry, circular dichroism, and dynamic birefringence. The thermodynamic parameters of the binding of the compounds with DNA and changes in the macromolecular parameters of the DNA molecule during complexation were determined. Based on the results of these studies, we suggested the models of bonding of these compounds to the double helix of DNA. It is shown that the mode of DNA binding with a phenoxazone derivative containing two (benzo-15-crown-5)-4′-yl radicals bonded via a fragment of glycine to chromophore depends on the type of the counterion in solution. In the presence of Na+, the chromophore is intercalated into the double helix of DNA; in the presence of K+, it is bound to DNA in the form of a dimer outside the double helix. The type of the counterion does not affect the mode of binding of other crown-containing compounds of actinocin with DNA. For compounds containing the (benzo-18-crown-6)-4′-yl radical, the mode of binding to DNA adepends only on the spacer length. [ABSTRACT FROM AUTHOR]
- Published
- 2009
- Full Text
- View/download PDF
43. Simulation of 2-D lateral light propagation in nematic-liquid-crystal cells with tilted molecules and nonlinear reorientational effect.
- Author
-
Beeckman, Jeroen, Neyts, Kristiaan, Hutsebaut, Xavier, Cambournac, Cyril, and Haelterman, Marc
- Subjects
- *
LIQUID crystals , *ANISOTROPY , *SOLITONS , *NONLINEAR theories , *THEORY of wave motion , *MAGNETIC fields - Abstract
In the general case the optical tensor of a nematic liquid crystal consists of nine nonzero elements, which makes it difficult to calculate light propagation in a liquid-crystal cell. For a two-dimensional (2-D) problem with TM polarization and a parallel liquid-crystal orientation where the molecules are only tilted and not twisted, the full problem can be calculated by using one magnetic field component, thus reducing the problem to a scalar one. This geometry is used to simulate the self-focusing effect which can lead to the generation of spatial optical solitary waves. This self-focusing occurs due to the optical nonlinear effect of field-induced director reorientation. Due to nondiagonal elements of the optical tensor, however, it is expected that the Poynting vector will deviate from the original propagation direction. Our simulations reveal that, in this case, the deviation will not cause the loss of the soliton-like beam propagation regime, but will rather give rise to a transverse undulating behaviour. [ABSTRACT FROM AUTHOR]
- Published
- 2005
- Full Text
- View/download PDF
44. Laser-Radiation-Induced Optical Anisotropy of Rhodamine Dye Solutions.
- Author
-
Pikulik, L., Chernyavskii, V., and Grib, A.
- Abstract
We have made spectral studies of induced optical anisotropy (its quantitative measure is the difference of refractive indices of the ordinary and extraordinary beams Δ n = n
o − ne ) of Rhodamine 6G and 4C solutions in glycerol upon excitation in the UV region of the absorption spectrum. The observed spectral dependences of Δ n of the above dye solutions excited in the UV (short-wavelength) and visible (long-wavelength) regions of the absorption spectrum are explained from the point of view of the molecular model. The proposed methods for investigating induced optical anisotropy of solutions of organic compounds make it possible to reliably determine the relative orientation of molecular electronic oscillators in the molecule skeleton and, consequently, the mutual orientation of the dipole moments of transitions. [ABSTRACT FROM AUTHOR]- Published
- 2000
- Full Text
- View/download PDF
45. Complementary analysis of Mueller-matrix images of optically anisotropic highly scattering biological tissues
- Author
-
Borovkova, M. (Mariia), Peyvasteh, M. (Motahareh), Dubolazov, O. (Olexander), Ushenko, Y. (Yurii), Ushenko, V. (Volodymyr), Bykov, A. (Alexander), Deby, S. (Stanislas), Rehbinder, J. (Jean), Novikova, T. (Tatiana), Meglinski, I. (Igor), Borovkova, M. (Mariia), Peyvasteh, M. (Motahareh), Dubolazov, O. (Olexander), Ushenko, Y. (Yurii), Ushenko, V. (Volodymyr), Bykov, A. (Alexander), Deby, S. (Stanislas), Rehbinder, J. (Jean), Novikova, T. (Tatiana), and Meglinski, I. (Igor)
- Abstract
Background: Using optical techniques for tissue diagnostics (so-called ‘optical biopsy’) has been a subject of extensive research for many years. Various groups have been exploring different spectral and/or imaging modalities (e.g. diffuse reflectance spectroscopy, autofluorescence, Raman spectroscopy, optical coherence tomography (OCT), polarized light microscopy, etc.) for biomedical applications. In this paper, we report on using multi-wavelength imaging Mueller polarimetry combined with an appropriated image post-processing for the detection of tissue malignancy. Methods: We investigate a possibility of complementary analysis of Mueller matrix images obtained for turbid tissue-like scattering phantoms and excised human normal and cancerous colorectal tissue samples embedded in paraffin. Combined application of correlation, fractal and statistical analysis was employed to assess quantitatively the polarization-inhomogeneous scattered fields observed at the surface of tissue samples. Results: The combined analysis of the polarimetric images of paraffin-embedded tissue blocks has proved to be an efficient tool for the unambiguous detection of tissue malignant transformation. A fractal structure was clearly observed at spatial distributions of depolarization of light scattered in healthy tissues in a visible range of spectrum, while corresponding distributions for cancerous tissues did not show such dependence. We demonstrate that paraffin does not destroy a fractal structure of spatial distribution of depolarization. Thus, the loss of fractality in spatial distributions of depolarization for cancerous tissue is related to the structural changes in the tissue sample induced by cancer itself and, therefore, may serve as a marker of the disease. Conclusions: The obtained results emphasize that a combined use of statistical, correlation and fractal analysis for the Mueller-matrix image post-processing is an effective approach for an assessment of variations of
- Published
- 2018
46. Orientational birefringence of uniaxially compressed PMMA networks in the unswollen state.
- Author
-
Kock, H. and Rehage, G.
- Abstract
Swollen PMMA networks show significant deviations from the theory of rubber elasticity. The unusual mechanical, optical and swelling properties have been explained by the existence of associations, well known for PMMA solutions. Unswollen PMMA networks show stress optical properties which are very similar to the networks swollen in carbon tetrachloride which is known as a strong complexing solvent. This indicates that associations exist in the bulk material. Swelling in carbon tetrachloride does not change the content of associations, only the glass transition temperature is reduced. Increasing the amount of crosslinking agent proves that the stress optical coefficient depends on the crosslinking density. This is contrary to the theoretical predictions. An explanation given by the effect of short network chains is not satisfactory. However, the consideration of a crosslinking chain instead of a crosslinking point gives a sufficient explanation. An oriented crosslinking chain gives a positive contribution to the total optical anisotropy while a PMMA chain shows a change from negative values (hindered rotation) to positive values (free rotation). [ABSTRACT FROM AUTHOR]
- Published
- 1985
- Full Text
- View/download PDF
47. Photoelasticity and structure of PMMA networks.
- Author
-
Kock, H. and Rehage, G.
- Abstract
The optical anisotropy Δα ( α=polarizability) of uniaxial deformed swollen and unswollen PMMA networks depends on the temperature. This is not in agreement with the Kuhn-Grün-theory. The temperature dependence and the negative values even above the glass transition temperature T can be explained by the existence of associations which cause a hindrance of the ester side group mobility. The swelling of the network in the optical isotropic solvent carbon tetrachloride does not degrade the associations and therefore not change the network structure; only T decreases. The situation is more complicated if optical anisotropic solvents are used. Polar aliphatic and aromatic solvents degrade the associations to some extend and the birefringence is shifted to more positive values. An additional change is caused by specific polymer solvent interactions. Aromatic solvents form complexes with the ester side group and the aliphatic solvent chloroform completely degrades the associations, which can be explained by the formation of hydrogen bonds. Sign and magnitude of the optical anisotropy allow statements on the orientation of the solvent molecules with respect to the polymer chain or the ester side group. [ABSTRACT FROM AUTHOR]
- Published
- 1984
- Full Text
- View/download PDF
48. Relaxational behavior of birefringence of aqueous carboxymethylcellulose under an alternating electric field at frequencies ranging from 0.1 Hz to 100 kHz.
- Author
-
Yamamoto, T., Mori, Y., Ookubo, N., Hayakawa, R., and Wada, Y.
- Abstract
The d. c. component of birefringence of aqueous carboxymethylcellulose (CMC) under an a. c. electric field was measured at frequencies ranging from 0.1 Hz to 100 kHz. Three samples of different molecular weights were studied with varying degree of neutralization, polymer concentration and added salt concentration. The dispersion curve of birefringence consists of three relaxation bands, A, B and C in order of decreasing frequency. Relaxation B with a negative relaxation strength is ascribed to end-over-end rotation of almost rodlike CMC molecules. Relaxation A with a positive strength is attributed to the relaxation of electrical polarizability along the minor axis of molecule. Relaxation C possesses also a positive strength and is induced by clusters of CMC molecules. [ABSTRACT FROM AUTHOR]
- Published
- 1982
- Full Text
- View/download PDF
49. Fabrication Techniques and Characteristics of Ultra-Thin Optical Polarizing Films Using Gold Island Films.
- Author
-
Baba, Kazutaka, Takakuwa, Makoto, and Miyagi, Mitsunobu
- Abstract
Fabrication techniques of ultra-thin optical polarizing films using gold island films have been investigated for the near-infrared region. The polarizing films are fabricated by stretching the periodic multilayers consisting of gold island layers and glass layers. We have experimentally investigated the optimum fabricating conditions necessary to induce large optical anisotropy into the gold island layers and have formed submicrometer-thick polarizing films with an extinction ratio of ≥20 dB in a near-infrared region longer than 800 nm. These polarizing films could be useful micro-polarizers for fiber-embedded in-line optical devices, micro-optics, and hybrid integrated optics. [ABSTRACT FROM AUTHOR]
- Published
- 1997
- Full Text
- View/download PDF
50. Unusual induction of optical anisotropy in polymer media by low-intensity polarized x-rays.
- Author
-
Prishchenov, A., Nizamov, N., and Karpei, A.
- Abstract
The induction of linear dichroism in (poly) methylmetacrylate films activated with Rhodamine 6G and its base in the spectral range of absorption of these dyes under the action of plane-polarized x-rays with wavelength 0.70Å and intensity 7.5·10
4 quanta per second has been revealed. The phenomenon is discussed from the standpoint of the radiochemical analog of the photochemical polarization-induced selection of organic molecules with allowance for the structural characteristics of the polymer film components. [ABSTRACT FROM AUTHOR]- Published
- 1997
- Full Text
- View/download PDF
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