Optical Constants (optical + constant)

Distribution by Scientific Domains


Selected Abstracts


Effect of annealing on the structural, electrical and optical properties of nanostructured TiO2 thin films

CRYSTAL RESEARCH AND TECHNOLOGY, Issue 9 2009
S. Sankar
Abstract Nanostructured titanium dioxide thin films were prepared using reactive pulsed laser ablation technique. Effects of annealing on the structural, morphological, electrical and optical properties are discussed. The structural, electrical and optical properties of TiO2 films are found to be sensitive to annealing temperature and are described with GIXRD, SEM, AFM, UV-Visible spectroscopy and electrical studies. X-ray diffraction studies showed that the as-deposited films were amorphous and at first changed to anatase and then to rutile phase with increase of annealing temperature. Optical constants of these films were derived from the transmission spectra and the refractive index dispersion of the films, subjected to annealing at different temperatures, is discussed in terms of the single oscillator-Wemple and Didomenico model. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]


Investigation of optical band gap in potassium acid phthalate single crystal

CRYSTAL RESEARCH AND TECHNOLOGY, Issue 6 2008
S. Krishnan
Abstract Optical absorption in photonic crystals of potassium acid phthalate has been measured at room temperature, from which the band gap has been determined and the optical band gap was calculated by using absorption spectrum. The analysis of absorption coefficient in the absorption region reveals a direct band gap of 3.70 eV. Further this study includes the theoretical calculations to determine the optical constant of the material and a technique for photonic band gap tuning which is minimally required to develop the optoelectronic device. It was confirmed that potassium acid phthalate crystal has maximum transparency in the entire visible region and hence it exhibits industrial application oriented properties. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]


Spectroscopic ellipsometry studies of Mg-doped ZnO thin films prepared by the sol,gel method

PHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 7 2009
Shenghong Yang
Abstract Zn1,xMgx O (ZMO) thin films with x = 0, 0.1, 0.2, and 0.3 were prepared on Si(100) substrates by the sol,gel method. The influence of Mg content on the structural and the optical properties was studied by X-ray diffraction and spectroscopic ellipsometry (SE) in the UV,visible region. The measured SE spectra were analyzed with an appropriate procedure to accurately determine the thickness and the optical constants of the thin films. It was found that the optical constants of the ZMO films are functions of the film composition. The refractive indices of the ZMO films decrease with increasing Mg content, and the optical bandgap energy exhibits nonlinear behavior or a bowing effect with the change of Mg mole fraction. A maximum band gap of ,3.91 eV was achieved at x = 0.3. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]


Spectroscopic phase modulated ellipsometry in application to some novel single and polycrystalline ternary compounds

PHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 11 2006
N. Mamedov
Abstract The results of the application of the spectroscopic phase modulated ellipsometry (SPME) to a series of novel ternary compounds from anisotropic to polycrystalline are presented to show the high effectiveness of this optical technique with regard to the dielectric function of the new materials. Besides, SPME in specular reflection mode to study the polarization degree of the light reflected at specular angle is shown to be very informative in determination of the best conditions for optical measurements on rough surfaces such as, for example, surfaces of the polycrystalline ternary thiogallate compounds studied in this work. An incoherent approach relating the measured depolarization with the surface variance and optical constants of a material or thin film is proposed. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]


Magneto-optical, optical and magnetic properties of the Mn1,xFex alloy films

PHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 1 2003
Y. V. Kudryavtsev
Abstract A set of Mn1,xFex alloy films with 0 < x < 1 has been prepared by face-to-face DC sputtering onto glass substrates kept at 293 K. The X-ray diffraction study reveals that an , -Fe phase with bcc-type of structure is the prevailing phase for the Mn1,xFex alloy films with 0.8 < x < 1, while , -Mn,Fe and , -Mn phases are dominant for 0.2 < x < 0.8 and x < 0.2, respectively. The experimental equatorial-Kerr-effect spectra for Mn1,xFex alloy films, which are observed only for x < 0.5, have nearly the same spectral shape (Fe-like), and differ from each other only by the intensity. They are nicely reproduced in the framework of the effective medium approximation by using scaled off-diagonal components of the dielectric function for pure Fe film and measured optical constants for the corresponding alloys. The optical properties of all the investigated alloys can be separated into three groups which are related to different prevailing crystalline structures of alloys. [source]


Optical spectra of bismuth sulfochloride crystals

PHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 1 2010
A. Audzijonis
Abstract We present the results of the ab initio theoretical study of the optical properties for paraelectric BiSCl crystal using the full potential linearized augmented plane wave (FP-LAPW) method as implanted in the Wien 2k code. For theoretical calculations of optical constants and functions we used the generalized gradient approximation (PBE-GGA), an improvement of the local spin-density approximation (LSDA) and recently Wu,Cohen (WC) proposed a new WC-GGA exchange-correlation energy functional. The dielectric function, refractive index, extinction coefficient, absorption coefficient, reflectivity, and energy loss function were calculated. The optical properties are analyzed and the origins of the peaks in the spectra are discussed in terms of the calculated density of states. [source]


Optical properties of conductive ZnO films near infrared frequency

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue S1 2009
T. Itoh
Abstract To know the optical constants, n and k, in transparent conductive zinc oxide (ZnO) films, both spectroscopic ellipsometry (SE) and reflectance-transmittance (RT) method have been adopted. The optical constants, n and k deduced from the SE are different from those estimated from the RT method. We will discuss these differences through the deduced physical parameters in magnetron sputtered Ga-doped ZnO films. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]


3124: Algorithms and instrumentation for quantified retinal oximetry in a snapshot

ACTA OPHTHALMOLOGICA, Issue 2010
AR HARVEY
Purpose To develop an instrument and techniques for useful absolute and relative clinical oximetry of the retina. Methods A novel snapshot multispectral imaging system has been optimised for retinal oximetry. Eight monochromatic images of the retina are recorded with a field of view of 24 degrees. Algorithms calculate the absorption of light at each point along delineated blood vessels and for each of the eight wavebands. Data inversion using an analytical model for light propagation enables oximetry at along the blood vessels. Spectral inversion has been refined using ray tracing and Monte Carlo modelling of light propagation using a realistic phantom eye. Results A comparison of Monte Carlo modelling of light propagation in the phantom retina with recorded images for blood of various oxygenations indicates the influence of several unknowns, including scatter from optical surfaces within the ophthalmoscope and eye, the geometry of the blood vessels and eye, the optical constants of the ocular media and the complexity of light propagation in the retinal structure. Relative oximetry within the retina is possible with repeatability of about 1% in the phantom and 5% in a real eye but the influence of various systematic effects can introduce systematic differences between actual and calculated oxygenation that can significantly exceed these values. Conclusion Although oximetry using only a very small number of spectral bands is possible, this is prone to systematic errors that can effect both absolute and relative oximetry. The ability to record eight spectral images in a single snapshot offers promise to provide an enhanced clinically useful and validated oximetry technique. [source]