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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

An application of optical interference to dynamic position measurement in three dimensions

Allan, James Donald Campbell January 1988 (has links)
This thesis is concerned with the measurement of the positions of points and bodies moving in trajectories in three dimensions, and the use of a new technique of optical interference which allows such measurements to be made dynamically. A variety of existing techniques for both static and dynamic three-dimensional position measurement are discussed, and the design of the new interferometer is introduced. The geometry of points, curves and surfaces in three dimensions is examined, with emphasis on the intersection of the point loci represented by the coordinate output of measuring instruments. The coordinates output by the interferometer represent surface loci which are quadric surfaces. A method of calculating the position and orientation of a body using three quadric surface intersection curves is presented. Diffraction of monochromatic light at an aperture is considered and it is shown that an interferometer working by division of wavefront can be used to obtain continuous information about the movement of the source of radiation, with that source free to move in up to three dimensions. A lens may be used to produce a compact instrument based on these principles. The diffraction integral equations are modified to incorporate the effect of a lens in the diffraction field. It is shown that even complex lenses can be represented by a few parameters in the diffraction equations. From the evaluation of these diffraction integrals, it is shown how the movement of interference fringes provides a coordinate output and how this is related to the locus of the radiation source. A method of obtaining very high resolution measurements of interference fringe pattern movement is presented. The interferometer was built and tested and the above theory verified in practice in a series of optical bench tests. The implementation of a system which uses this interferometer to measure the dynamic performance of industrial robots is considered. The optimum positions for the instruments are derived, and the method of designing the interferometer to give the required resolution is presented.
12

The effects of continuous wave interference on Global Positioning System software radio processing

Gopalan, Kavitha. January 2001 (has links)
Thesis (M.S.)--Ohio University, August, 2001. / Title from PDF t.p.
13

AN EXTENSION TO THE ANALYSIS OF THE SHIFT-AND-ADD METHOD: THEORY AND SIMULATION (SPECKLE, ATMOSPHERIC TURBULENCE, IMAGE RESTORATION).

WEST, KAREN FRANCES. January 1985 (has links)
The turbulent atmosphere degrades images of objects viewed through it by introducing random amplitude and phase errors into the optical wavefront. Various methods have been devised to obtain true images of such objects, including the shift-and-add method, which is examined in detail in this work. It is shown theoretically that shift-and-add processing may preserve diffraction-limited information in the resulting image, both in the point source and extended object cases, and the probability of ghost peaks in the case of an object consisting of two point sources is discussed. Also, a convergence rate for the shift-and-add algorithm is established and simulation results are presented. The combination of shift-and-add processing and Wiener filtering is shown to provide excellent image restorations.
14

Examining the effectiveness of interactivity in a 3-dimensional web-based tutorial on interference phenomenon

Li, Qiaowu. January 2002 (has links)
Thesis (M.S.)--Mississippi State University. Department of Physics and Astronomy. / Title from title screen. Includes bibliographical references.
15

POLYNOMIAL FIT OF INTERFEROGRAMS.

KIM, CHEOL-JUNG. January 1982 (has links)
The conventional Zernike polynomial fit of circular aperture interferograms is reviewed and a more quantitative and statistical analysis is added. Some conventional questions such as the required number of polynomials, sampling requirements, and how to determine the optimum references surface are answered. Then, the analysis is applied to the polynomial fit of noncircular aperture interferograms and axicon interferograms. The problems and limitations of using Zernike polynomials are presented. A method of obtaining the surface figure error information from several smaller subaperture interferograms is analyzed. The limitations of the analysis for testing a large flat, a large parabola, or an aspheric surface are presented. The analysis is compared with the local connection method using overlapped wavefront information. Finally, the subaperture interferogram analysis is used to average several interferograms and to analyze lateral shearing interferograms.
16

Alternative conceptions concerning interference and diffraction of light

Coetzee, Annaretha January 1998 (has links)
A research report submitted in partial fulfillment of the requirements for the degree of Master of Science in Education at the Faculty of Science, University of the Witwatersrand, Johannesburg. / The aim of this study was to determine whether alternative conceptions about interference and diffraction do indeed exist, to identify the most important of these conceptions and to determine whether these conceptions relate to textbooks, as one of the main sources of students' knowledge. An analysis of secondary level textbooks and tertiary level non-calculus textbooks revealed that presentations of constructive and destructive interference, diffraction and other related aspects are treated inconsistently and in some cases contradictorily by different authors. The research instrument was a Physical Optics test which Physics students of the Technikon Pretoria wrote. This test revealed that alternative conceptions on elementary principles of interference and diffraction of light do exist and that they relate to textbook presentations. This study reveals that (i) the terms in phese and out of phase are not consistently used in different textbooks; (ii) the definitions of constructive and destructive interference in terms of phases cause major aiternative conceptions, (iii) the interrelation between interference and diffraction is not clarified. / AC2017
17

Estudo de materiais fotossensíveis utilizando exposições holográficas / Study of photosensitive materials by using holographic exposures

Avila, Luis Fernando de, 1980- 07 December 2010 (has links)
Orientador: Lucila Helena Deliesposte Cescato / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Fisica Gleb Wataghin / Made available in DSpace on 2018-08-15T19:36:27Z (GMT). No. of bitstreams: 1 Avila_LuisFernandode_D.pdf: 1824665 bytes, checksum: 6cab44933ac386ebd3097bd193d85e0f (MD5) Previous issue date: 2010 / Resumo: Materiais fotossensíveis são materiais que sofrem alterações físico-químicas quando expostos à luz de comprimento de onda apropriado. A gama de aplicações para estes materiais é enorme, entre elas as que apresentam maiores exigências em termos do próprio material são as aplicações em armazenagem de informação e imagens. Para avaliar o potencial de um material para uma dada aplicação é necessário entender os mecanismos fotossensíveis envolvidos assim como caracterizar suas propriedades, tais como: sensibilidade espectral, modulação óptica máxima, reversibilidade, estabilidade térmica, etc. Nesta tese de doutorado foi proposto e demonstrado um método para processar os sinais de auto-difração que, além de permitir a medida simultânea e independente das modulações de índice de refração e de coeficiente de absorção, nos permite medir a evolução temporal das modulações e a constante cinética das reações fotossensíveis. Esta técnica foi utilizada para estudar três tipos de materiais fotossensíveis: fotorresinas positivas (SC 1827 da Shipley), fotorresinas negativas (SU-8 da Microchem) e vidros calcogenetos (em particular composições com Sulfeto de Antimônio). As medidas foram realizadas utilizando-se dois interferômetros diferentes: um com óptica para o visível e outro para o ultravioleta. Além disso, foi observada uma modulação de elétrons secundários nas imagens de microscopia eletrônica de amostras de fotorresinas negativas SU8 expostas holograficamente / Abstract: Photosensitive materials are materials that change their optical properties when exposed to light of appropriate wavelength. The range of applications of such materials is very wide. Among these applications the storage of images and information is that present higher requirements in terms of the material itself. To evaluate the potential of a material for a given application it is necessary to understand the mechanisms involved as well as to characterize their photosensitive properties such as spectral sensitivity, maximum optical modulation, reversibility, thermal stability, etc. In this thesis we propose and demonstrate a method for processing the selfdiffraction the signals that allows the simultaneous and independent measurement of the modulations of refractive index and absorption coefficient as well as to measure the temporal evolution of such modulations and their corresponding kinetic constant of the photo-reactions. This technique was employed to study three types of photosensitive materials: positive photoresist (SC 1827 from Shipley), negative photoresist (Microchem SU-8) and chalcogenide glasses (in particular compositions with Antimony Sulfide). Measurements were performed using two different interferometers, one with optics for the visible and one for the ultra-violet. Moreover, a modulation of secondary electrons was observed in the electronic microscopy images of the SU8 negative photoresist samples exposed holographically / Doutorado / Ótica / Doutor em Ciências

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