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Articles 1 - 8 of 8
Full-Text Articles in Physics
A More General Diffusion Model For Lightning Radiative Transfer, Elliott Paul Saint-Pierre
A More General Diffusion Model For Lightning Radiative Transfer, Elliott Paul Saint-Pierre
UNLV Theses, Dissertations, Professional Papers, and Capstones
A more general diffusion model for lightning radiative transfer is presented. The development is based on the work published by Koshak et al (J. Geo. Phys. Res., vol. 99, (D7), 14361-371, (1994). In this thesis, the diffusion coefficient is allowed to vary as a function of the radial component of the cloud and cylindrical geometry is used. Different approximations in the analysis of the resulting radial equation are provided. The method of Frobenius permits the obtention of a complete solution. Possibilities and means for further development of this research are included.
Tilted Photoalignment Of A Nematic Liquid Crystal Induced By A Magnetic Field, Denis Andrienko, Yuri Kurioz, Yuri Reznikov, Charles Rosenblatt, Rolfe Petschek, Oleg Lavrentovich, Darius Subacius
Tilted Photoalignment Of A Nematic Liquid Crystal Induced By A Magnetic Field, Denis Andrienko, Yuri Kurioz, Yuri Reznikov, Charles Rosenblatt, Rolfe Petschek, Oleg Lavrentovich, Darius Subacius
Oleg Lavrentovich
Nematic liquid crystal cells with polyvinyl cinnamate coated substrates were subjected to ultraviolet light. When this was done in the presence of an oblique magnetic field the photoalignment was found to be temporally and thermally robust, with a large pretilt angle and weak polar anchoring. Moreover, two easy axes with equal and opposite pretilt angle were obtained, such that a magnetic field could switch the director from one easy axis to the other. (C) 1998 American Institute of Physics.
Three-Dimensional Orientational Order In The Bulk And On The Surface Of Polymer Films And Its Effect On Liquid-Crystal Alignment, O. V. Yaroshchuk, Yu. Zakrevskyy, Satyendra Kumar, J. Kelly, Liang-Chy Chien, J. Lindau
Three-Dimensional Orientational Order In The Bulk And On The Surface Of Polymer Films And Its Effect On Liquid-Crystal Alignment, O. V. Yaroshchuk, Yu. Zakrevskyy, Satyendra Kumar, J. Kelly, Liang-Chy Chien, J. Lindau
Liang-Chy Chien
The correlation between orientation ordering of polymer chains in the bulk of polymer film and at the polymer-liquid-crystal (LC) interface has been studied to determine it's role in LC alignment. The bulk and surface ordering of polymer were investigated by null ellipsometry and x-ray reflectivity, respectively. Two kinds of liquid-crystalline polymers were used; side-chain azopolymers with azochromophores containing hydrophobic OC(4)H(9) alkyl chain (P1) and strongly polar NO(2) group (P2) as the end substituents. The uniaxial tilt orientation of azochromophores in the films of both polymers was induced by the oblique irradiation with unpolarized UV light. The two polymers exhibit similar …
Studying Light Pollution In And Around Tucson, Az, Rachel K. Nydegger
Studying Light Pollution In And Around Tucson, Az, Rachel K. Nydegger
Physics Capstone Projects
Eight housed data logging Sky Quality Meters (SQMs) are being used to gather light pollution data in southern Arizona: one at the National Optical Astronomy Observatory (NOAO) in Tucson, four located at cardinal points at the outskirts of the city, and three situated on surrounding mountain tops. To examine specifically the effect of artificial lights, the data are reduced to exclude four natural contributors to lighting the night sky, namely, the sun, the moon, and the Milky Way. Faulty data (i.e., when certain parameters were met) were also excluded. Data were subsequently analyzed by a recently developed night sky brightness …
Design And Construction Of An Optical Tweezers, Pavel Aprelev
Design And Construction Of An Optical Tweezers, Pavel Aprelev
Honors Theses
We constructed an optical tweezers apparatus, used it to trap transparent micron-sized particles, and moved those particles within a sample by moving the sample relative to the focal point of the trapping beam. The optical trap was based on the fact that focused coherent light creates forces on dielectric objects that point towards the focal point. The magnitude and the span of the force are dependent on the size of the focal point of the beam - generally around 1µm - and the intensity of light. We used an 808 nm 200 mW laser and a piezoelectric stage to trap …
Potential For High Resolution Microscintigraphy Using Polycapillary Optics, Patrick Richard Conlon
Potential For High Resolution Microscintigraphy Using Polycapillary Optics, Patrick Richard Conlon
Legacy Theses & Dissertations (2009 - 2024)
Scintigraphy, also known as nuclear imaging, is the process of imaging an object that has been labeled with a radioactive material. A novel technique employing polycapillary optics for very high - resolution scintigraphy is presented. The small channel size and angular selectivity of polycapillary optics allow them to act as multiple-hole collimators and be used with high - resolution detectors. The ability of the optics to work with high resolution detectors allow the system to discriminate against scatter, thus negating the need for energy sensitive detectors, which are known to have poor resolution. Therefore the use of polycapillary optics presents …
Mueller Based Scatterometry And Optical Characterization Of Semiconductor Materials, Gangadhara Raja Muthinti
Mueller Based Scatterometry And Optical Characterization Of Semiconductor Materials, Gangadhara Raja Muthinti
Legacy Theses & Dissertations (2009 - 2024)
Scatterometry is one of the most useful metrology methods for the characterization and control of critical dimensions (CD) and the detailed topography of periodic structures found in microelectronics fabrication processes. Spectroscopic ellipsometry (SE) and normal incidence reflectometry (NI) based scatterometry are the most widely used optical methodologies for metrology of these structures. Evolution of better optical hardware and faster computing capabilities led to the development of Mueller Matrix (MM) based Scatterometry (MMS). Dimensional metrology using full Mueller Matrix (16 element) scatterometry in the wavelength range of 245nm-1000nm was discussed in this work. Unlike SE and NI, MM data provides complete …
The Classical Limit Of Quantum Optics: Not What It Seems At First Sight, Yakir Aharonov, Alonso Botero, Shmuel Nussinov, Sandu Popescu, Jeff Tollaksen, Lev Vaidman
The Classical Limit Of Quantum Optics: Not What It Seems At First Sight, Yakir Aharonov, Alonso Botero, Shmuel Nussinov, Sandu Popescu, Jeff Tollaksen, Lev Vaidman
Mathematics, Physics, and Computer Science Faculty Articles and Research
What light is and how to describe it has always been a central subject in physics. As our understanding has increased, so have our theories changed: geometrical optics, wave optics and quantum optics are increasingly sophisticated descriptions, each referring to a larger class of phenomena than its predecessor. But how exactly are these theories related? How and when wave optics reduces to geometric optics is a rather simple problem. Similarly, how quantum optics reduces to wave optics has also been considered to be a very simple business. It is not so. As we show here the classical limit of quantum …