Dissertations / Theses on the topic 'Refractions'
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Lancaster, Linwood R. "Refractions." Fogler Library, University of Maine, 2003. http://www.library.umaine.edu/theses/pdf/LancasterLR2003.pdf.
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Paxson, Patricia P. "Reflections on, and refractions in, painting practices." Thesis, Goldsmiths College (University of London), 2004. http://research.gold.ac.uk/176/.
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My aim in the written thesis is to scrutinize a particular stage in the process of image making by means of ideas generated by psychoanalytic theory, in particular Lacan’s concept of the gaze. I propose a three stage model of image making: 1) planning, 2) absorption or ‘un-thought’, and 3) judging; they are seen together as a spiral process. My primary interest is the second stage, both in my studio practice and in the written thesis. In the studio this can be seen in the conjunction between passages emphasizing energy, for instance passages emphasizing a ‘re-invigoration’ of the figure by means of an investigation into mark making and cartoon elements, and passages emphasizing form and colour. In the written work, by using Lacan’s concept of the gaze as template, then employing ideas such as ‘figure’ and ‘dissimulation’ within the libidinal economy (Lyotard), syncretistic scanning and the ability of the primary processes to learn and develop (Ehrenzweig), and the matrixial gaze (Lichtenberg-Ettinger), I aim to illuminate the ‘un-thought’ stage of image making by means of a consideration of libidinal as well as semiotic processes. By including aspects of schizoanalysis (Deleuze and Guattari), I ‘re-contextualize’ Lacan’s concepts of ‘lack’ and the empty signifier and retain his other ideas relating to his (late) concept of the gaze. Schizoanalysis, in providing an extended concept of the unconscious, aids in re-considering Lacan’s concept of the gaze within the context of the process of image making. Working from this basis I propose a grouping of (existing) ideas that I term the libidinal gaze, brought together for the purpose of reflecting on the un-thought stage in the process of image making. In doing so, I consider both concepts of perception as influenced by the processes and energy of the unconscious, and concepts of the unconscious as reflected through post-Freudian and post-Lacanian psychoanalytic thought.
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Yuan, Ziqi. "“Isms” and the Refractions of World Literature in May Fourth China." The Ohio State University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=osu1437559868.
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Warner, Ruth Virginia. "In the hall of mirrors : literary refractions of Russian yuletide rituals (sviatki) /." The Ohio State University, 1999. http://rave.ohiolink.edu/etdc/view?acc_num=osu1488192447427563.
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Kim, DoYeon. "Paul Schoenfield's 'Refractory' Method of Composition: A Study of Refractions and Sha’atnez." University of Cincinnati / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1563295242704718.
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Sosa, Ortega Jorge Raymundo Rudy Paul. "Refractions a collection of three pieces for solo instruments and fixed electronic media /." Diss., UMK access, 2008.
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Thesis (D.M.A.)--Conservatory of Music and Dance. University of Missouri--Kansas City, 2008.First piece for amplified clarinet and fixed electronic media, the second piece for electric guitar and fixed electronic media, and the third piece for amplified high voice (soprano or tenor) and fixed electronic media. "A dissertation in music composition." Advisor: Paul Rudy. Typescript. Vita. Title from "catalog record" of the print edition Description based on contents viewed Apr. 14, 2009 Online version of the print edition.
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Caenepeel, Mimo. "Aspect, temporal ordering and perspective in narrative fiction." Thesis, University of Edinburgh, 1989. http://hdl.handle.net/1842/6594.
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Throughout the reading process, a narrative text produces various sensations of immediacy or distance. One important reason for this is that a narrative will in some places present situtations from a particular perspective, with which the reader is implicitly invited to identify, while in other places it will describe situations as independent of any perspective. If a perspective (that of the narrator, or that of a character in the text) is introduced, the narrative reflects an individual's (potentially fallible) perceptions, attitudes or beliefs; and this creates the impression of perspectival immediacy. If no perspective is introduced, on the other hand, the narrative pretends to relate "objective facts" within the fiction; and this creates the impression of perspectival distance. Thus the contrast between perepectivally situated and perepectivally non-situated sentences in a narrative produces perspectival refractions. The difference between both types of sentences, however, is often felt to be recalcitrant to a full linguistic analysis. For example, it is generally assumed that the perspectival status of a sentence is determined by the presence or absence of aubject-oriented elements in the sentence. But although such elements play an important role in focusing perspective, they need not occur in a sentence for the sentence to be perspectivally situated. In Chapter 1 of this dissertation, we draw attention to an observation which has received very little attention in the existing literature on perspective: per pectivally non-situated sentences typically move narrative time forward (in the sense that the order of the sentences on the page mimics temporal progression on the imaginary time line of the narrative), while perspectivally situated sentences do not convey forward movement in time. In other words, there appears to be a relationship between temporal ordering and perspective. Our aim is to specify the precise nature of this relationship. To do so, we first of all try to establish what determines the temporal relationship between consecutive sentences in narrative. We take as the starting point for our discussion some recent theories in the field of formal semantics which define this relationship in terms of the aspectual type a sentence belongs to. In Chapter 2, we explore to what extent these theories enable us to explain the apparent correlation between temporal ordering and perspective in narrative texts. In Chapters 3-5, we propose a detailed analysis of the relationship between the aspectual properties of sentences and their perspectival characteristics. Our central claim is that sentences exhibiting a state profile always introduce a perspective into a narrative. We try to make explicit why this is the case. In Chapter 6, the conclusions of this analysis are integrated into a more general theory of perspective in narrative fiction.
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Greenberg, M. "Futurism and science : refractions of scientific knowledge in the work of Filippo Tommaso Marinetti." Thesis, University of Cambridge, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.599667.
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The thesis aims to analyse the relationship that F. T. Marinetti established between innovations in science at the fin-de-siècle and his Futurist movement. Chapter 1 examines the introduction and repercussions of Comtian Positivism in Italy. Chapter 2 provides a history of the relationship between science and literature in order to argue that Marinetti’s project was in certain respects related to the genre of ‘proto-science-fiction’. Following the more general theoretical and literary historical background of the first two chapters, Marinetti’s early French work as a Symbolist is read in Chapter 3 through representations of the neurological condition of synaesthesia in his and others poetry. The experience of simultaneity is investigated in Chapter 4 as a consequence of innovations in the study of electricity and in particular to the impact of the widespread use of Guglielmo Marconi’s wireless telegraph. In Chapter 5 Marinetti’s machine idolatry is contextualised as part of the late nineteenth century popular understanding of the first two laws of thermodynamics, the conservation of energy and entropy, which revolutionise the interpretation of the lifecycle. Finally, in Chapter 6, the discussion of thermodynamics in Marinetti’s Futurism is extended to an analysis of its links to debates on evolution and degeneration, and more specifically to the impact of a national ‘hygienic’ agenda for the purification of society.
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Espinosa, Ruben. "Shakespeare's Marian refractions: Shaping masculine identity via the Virgin Mary in post-Reformation England." Connect to online resource, 2008. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3303838.
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Vallance, Scott, and scottvallance@internode on net. "Trilinear Projection." Flinders University. School of Informatics & Engineering, 2005. http://catalogue.flinders.edu.au./local/adt/public/adt-SFU20050714.113416.
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In computer graphics a projection describes the mapping of scene geometry to the screen. While linear projections such as perspective and orthographic projection are common, increasing applications are being found for nonlinear projections, which do not necessarily map straight lines in the scene to straight lines on the screen. Nonlinear projections occur in reflections and refractions on curved surfaces, in art, and in visualisation.
This thesis presents a new nonlinear projection technique called a trilinear projection that is based on the trilinear interpolation of surface normals used in Phong shading. Trilinear projections can be combined to represent more complicated nonlinear projections. Nonlinear projections have previously been implemented with ray tracing, where rays are generated by the nonlinear projections and traced into the scene. However for performance reasons, most current graphics software uses scanline rendering, where a scene point is imaged on a screen as a function of the projection parameters. The techniques developed in this thesis are of this nature.
This thesis presents several algorithms used in trilinear projection:
1. An algorithm to analytically determine which screen locations image a given scene point.
2. An algorithm that correctly connects projected vertices. Each scene point may be imaged multiple times, which means a projected scene triangle may form from one to four different shapes of from two to nine vertices. Once connected, the projected shapes may be rendered with standard scanline algorithms.
3. An algorithm to more accurately render the curved edges between projected vertices.
4. A scene-space edge-clipping algorithm that handles continuity issues for projected shapes across composite projections.
The trilinear projection technique is demonstrated in two different application areas: visualisation, and reflections and refractions. Specifically, various nonlinear projections that are congruent with pre-existing visualisation techniques are implemented with trilinear projections and a method for approximating the reflections and refractions on curved surfaces with trilinear projections is presented. Finally, the performance characteristics of the trilinear projection is explored over various parameter ranges and compared with a naive ray tracing approach.
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Drum, Mary Therese, and mikewood@deakin edu au. "Women, religion and social change in the Philippines: Refractions of the past in urban filipinas' religious practices today." Deakin University. School of Social Inquiry, 2001. http://tux.lib.deakin.edu.au./adt-VDU/public/adt-VDU20060825.115435.
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This research is an exploration of the place of religious beliefs and practices in the life of contemporary, predominantly Catholic, Filipinas in a large Quezon City Barangay in Metro Manila. I use an iterative discussion of the present in the light of historical studies, which point to women in pre-Spanish Filipino society having been the custodians of a rich religious heritage and the central performers in a great variety of ritual activities. I contend that although the widespread Catholic evangelisation, which accompanied colonisation, privileged male religious leadership, Filipinos have retained their belief in feminine personages being primary conduits of access to spiritual agency through which the course of life is directed. In continuity with pre-Hispanic practices, religious activities continue to be conceived in popular consciousness as predominantly womens sphere of work in the Philippines. I argue that the reason for this is that power is not conceived as a unitary, undifferentiated entity. There are gendered avenues to prestige and power in the Philippines, one of which directly concerns religious leadership and authority. The legitimacy of religious leadership in the Philippines is heavily dependent on the ability to foster and maintain harmonious social relations. At the local level, this leadership role is largely vested in mature influential women, who are the primary arbiters of social values in their local communities. I hold that Filipinos have appropriated symbols of Catholicism in ways that allow for a continuation and strengthening of their basic indigenous beliefs so that Filipinos religious beliefs and practices are not dichotomous, as has sometimes been argued. Rather, I illustrate from my research that present day urban Filipinos engage in a blend of formal and informal religious practices and that in the rituals associated with both of these forms of religious practice, women exercise important and influential roles. From the position of a feminist perspective I draw on individual womens articulation of their life stories, combined with my observation and participation in the religious practices of Catholic women from different ethnic and socio-economic backgrounds, to discuss the role of Filipinas in local level community religious leadership. I make interconnections between womens influence in this sphere, their positioning in family social relations, their role in the celebration of All Saints and All Souls Days in Metro Manilas cemeteries and the ubiquity and importance of Marian devotions. I accompany these discussions with an extensive body of pictorial plates.
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Kelly, Mary Rose. "Discourse, desire, diaphanous skins, reflections and refractions of an SF masculine in two novels by Samuel R. Delany." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape9/PQDD_0015/MQ47953.pdf.
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Beaman, Heather. "Reflection-Refraction." VCU Scholars Compass, 2009. http://scholarscompass.vcu.edu/etd/1888.
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I find my inspiration by looking at the world around me. I take snapshots, compose photographs, and collect physical objects from my surroundings. I interpret these materials by layering printmaking, mixed media, and alternative photographic processes. I use the simplification of the human form when developing the composition. As my work takes shape, I present a universal person placed in a situational narrative. Layering the human figure with my travels and experiences creates a pause or an intimate moment that the viewer shares with the art work.
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Nešpor, Dušan. "Studie šíření elektromagnetické vlny v heterogenních strukturách." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2010. http://www.nusl.cz/ntk/nusl-218636.
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The sight of work is study form high frequency electromagnetic wave in inhomogeneous materials. The main are refractions and reflection on boundary of materials with different properties and form electromagnetic wave in periodic structure. The work contain analytic and numeric solution. The numeric solution was realized in program COMSOL.
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Rodgman, D. N. "Refraction in volume graphics." Thesis, Swansea University, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.638701.
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In this study, we have proposed several methods for sampling field-based representations of refraction attributes, and analysed these methods in terms of the quality and accuracy of the results produced. We have identified two types of anomalies that affect the correctness of some methods, and found that the best of these methods is capable of producing images of equal quality to surface-graphics techniques. Our approach produces good results with functionally defined models, and discrete volumetric data, in the absence of noise. We have also established that this approach allows the modelling and rendering of types of objects that cannot be represented in surface graphics (e.g. objects with a continuous, non-uniform refractive index). Where noise is present in volumetric data, it significantly affects the correctness of rendering refraction, usually resulting in images of poor quality. A number of methods for smoothing have been examined, including low-pass filtering and various types of nonlinear diffusion. We have shown that regularised anisotropic nonlinear diffusion is a powerful and effective method for processing noisy volumetric data sets in order to improve the quality of images featuring refraction. High quality images featuring refraction often take a long time to render. We have presented the design and implementation of a parallel, open source volume graphics rendered which supports refraction and multi-volume scenes. A large number of issues related to a efficient operation of a parallel renderer have been examined, and a high-performance, scaleable parallel renderer has been developed, which performs efficiently on both networked clusters, and shared memory multi-processor machines.
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Valle, G. Raul del. "Model parameterization in refraction seismology." Thesis, McGill University, 1986. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=66057.
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Turpin, Avilés Alejandro. "Conical refraction: fundamentals and applications." Doctoral thesis, Universitat Autònoma de Barcelona, 2015. http://hdl.handle.net/10803/322801.
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El fenomen de la refracció cònica en cristalls biaxials és conegut des del 1832, quan William Hamilton va predir matemàticament que un feix de llum idealment col·limat travessant un cristall biaxial paral·lelament a un dels eixos òptics del cristall, es refracta com un conus asimètric i emergeix del cristall com un cilindre de llum, la secció transversal del qual forma un anell de llum. La posterior observació del fenomen només uns mesos després per part de Humphrey Lloyd, va convertir la refracció cònica en un dels primers fenòmens observats després de la seva predicció, així com va donar el triomf de la teoria ondulatòria de la llum sobre la teoria corpuscular. A finals dels anys 70 del segle passat, Belsky i Khapalyuk van presentar la formulació difractiva del fenomen per a feixos amb simetria cil·líndrica, la qual va estar re-formulada per Berry durant la passada dècada.
En aquesta tesi, explorem la refracció cònica d’una manera àmplia, alhora que profunda. Primerament, demostrem que, després d’un cert desenvolupament, la teoria de Berry pot ser utilitzada per estudiar la propagació de qualsevol feix, independentment del seu estat de polarització o perfil transversal, tant al llarg de l’eix òptic com a fora del mateix i per a qualsevol nombre de cristalls biaxials en cascada. Aquesta teoria difractiva també és utilitzada per a demostrar que, només ajustant la raó entre el radi de l’anell de refracció cònica i l’amplada del feix d’entrada, es poden aconseguir feixos molt dispars i que donen lloc a singularitats òptiques i vector beams molt interessants. Seguidament, demostrem que la refracció cònica pot ser entesa com la transformació de les ones incidents en dues ones còniques, la interferència de les quals dóna lloc als típics anells dobles al pla focal. A més a més, proposem una teoria alternativa que permet calcular el patró final després del cristall de qualsevol tipus de feix d’entrada, només tenint en compte refracció de vectors d’ona incidents i ho apliquem al cas particular de tenir múltiples cristalls en cascada. En particular, demostrem un sistema de multiplexació i de-multiplexació de senyals monocromàtiques per a aplicacions en les comunicacions òptiques en espai lliure basat en tres cristalls biaxials en cascada.
Tot l’estudi anterior serveix per a la realització de noves propostes per a trampes òptiques per a àtoms neutres i partícules absorbents. En aquest sentit, demostrem tant teòricament com experimental que les estructures fosques que es generen amb refracció cònica són de gran utilitat per a atrapar àtoms ultra-freds, en col·laboració amb el grup del Prof. Gerhard Birkl a la Technische Universität Darmstadt. Tanmateix, utilitzem la particular distribució de polarització dels anells de refracció cònica per a construir una ampolla òptica re-configurable en temps real i que permet carregar i descarregar partícules macroscòpiques absorbents.
També ens endinsem en el món de l’òptica quàntica a través de l’estudi de la generació de segon harmònic tant de tipus I com de tipus II a partir d’un feix de refracció cònica i demostrem que les propietats del feix de segon harmònic són pràcticament iguals a les del feix fonamental. Finalment, fem una proposta teòrica per a dissenyar un dispositiu capaç de detectar entrellaçament quàntic en moment lineal entre fotons bessons on l’element clau és un cristall biaxial.The conical refraction phenomenon in biaxial crystals is known since 1832 when William Hamilton predicted mathematically that and ideally collimated light beam passing through a biaxial crystal parallel to one of the crystal optic axes would refract as an slanted cone within the crystal and emerge as a hollow light cylinder, whose transverse profiles forms a light ring. The afterwards observation of the phenomenon by Humphrey Lloyd made the conical refraction phenomenon to become one of the first phenomenon that were observed after their prediction, as well as the one who tip the scales towards the wave theory of light against the corpuscular theory. In the late 70s, Belsky and Khapalyuk presented the diffractive formulation of the phenomenon for cylindrically symmetric beams, this formalism being reformulated by Berry during the last decade. In this thesis, we explore conical refraction in deep and present some applications of this phenomenon. Firstly, we show that, after some theoretical development, Berry’s formalism can be used to predict the transformation of beams along any propagation direction, no matter the state of polarization or transverse profile they posses and the number of crystals in cascade used. The diffractive theory is also used to demonstrate that, by simply tuning the ratio between the conical refraction ring radius and the waist radius of the input beam, a rich variety of light beams and optical singularities can be generated. Then, we show that conical refraction can be understood as the transformation of the input plane waves into a pair of conical waves whose interference leads to the characteristic concentric bright rings at the focal plane. Additionally, we propose an alternative theory that allows calculating the resulting pattern beyond the biaxial crystal for any input light beam by considering splitting of input wave-vectors and we apply this simple formalism to predict the resulting pattern for a cascade of crystals. In particular, we demonstrate a multiplexing and de-multiplexing system for monochromatic signals for free space optical communications applications based on three biaxial crystals in cascade. The latter results are used to propose and realize different optical architectures for optical trapping of both ultra-cold atoms and absorbing particles. In this sense, show both theoretically and experimentally that dark optical geometries generated with conical refraction are of complete usefulness to trap Bose–Einstein condensates, in collaboration with the group of Prof. Gerhard Birkl at the Technische Universität Darmstadt. Additionally, we use the particular polarization distribution along the conical refraction rings to build a reconfigurable optical bottle capable to load and unload macroscopic absorbing particles at wish, in collaboration with the group of Prof. Wieslaw Krolikowski at the Australian National University. We also explore the world of quantum optics throughout the analysis of both type I and type II second harmonic generation of a conically refracted beam and we demonstrate that the second harmonic beam keeps most of the properties of the fundamental harmonic beam. Finally, we present a theoretical proposal to design an optical device able to detect linear momentum entanglement between twin photons, a biaxial crystal being the key element of the device.
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Trendall, Chris. "Ray tracing refraction in hardware." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape3/PQDD_0016/MQ49742.pdf.
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Wu, Qi. "Negative refraction by photonic nanostructures." Connect to online resource, 2008. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3337163.
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Martos, Justin Riley. "Fault Mapping with the Refraction Microtremor and Seismic Refraction Methods along the Los Osos Fault Zone." DigitalCommons@CalPoly, 2012. https://digitalcommons.calpoly.edu/theses/873.
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The presence of active fault traces in proximity to any new infrastructure project is a major concern for the design process. The relative displacements that can be experienced in surface fault rupture during a seismic event must be either entirely avoided or mitigated in some way. Blind faults present a significant challenge to engineers attempting to identify these hazards. Current standards of practice employed to locate these features are time consuming and costly. This work investigates the geophysical methods of refraction microtremor (ReMi) and seismic refraction with regard to their applicability in this task. By imaging a distinct lateral variation in the shear wave velocity (Vs) profile across a short horizontal distance, these methods may provide a means of constraining traditional investigation techniques to a more focused area. The ReMi method is still very new, but holds key advantages over other geophysical methods in its ease of application and ability to achieve good results in highly urban settings. It is one of the few geophysical techniques that does not suffer in the presence of high amplitude ambient vibrations. The seismic refraction method is here applied in an attempt to corroborate data obtained through the ReMi analysis procedure. Sensitivity, precision parametric studies are carried out in order to learn how to best apply the ReMi method. Both tests are then applied at a previously trenched fault trace to determine whether the data can be matched to the subsurface information. Finally, the methods are deployed at a location with an inferred fault trace where little to nothing is known about the subsurface. The precision study indicates a coefficient of variation for the ReMi method on the order of 7%. At the known fault trace both methods generally agree qualitatively with available subsurface data and each other. Using the ReMi method, a marked shift is observed in the Vs profile laterally across the fault trace. In the case of the inferred fault trace, the same type of lateral variation in the Vs profile is observed using the ReMi method. The seismic refraction at this site does not agree with the ReMi data, but seems reasonable given the visible geomorphology. Receiver arrays placed in close proximity to the inferred fault trace recorded erratic signals during seismic refraction testing, and displayed abnormal response modes after transforming the ReMi data to frequency-slowness space. These anomalies may possibly be attributed to the presence of abnormal subsurface structural geometry indicative of faulting.
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Dirdal, Christopher Andrew. "Negative Refraction in Non-Magnetic Metamaterials." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for elektronikk og telekommunikasjon, 2012. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-19337.
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The discoveries and subsequent developments within the field of metamaterials have opened up for novel light-matter interactions towards the engineering of light behavior. The astonishing phenomenon of negative refraction remains challenging to realize for visible frequencies, and non-magnetic gain metamaterials have been proposed towards this end. This thesis pursues this idea by presenting a conceptual framework for which to understand the requirements and possibilities emerging from the causal behavior of the dielectric response. This results in clear and concrete instructions on how the dielectric response must be designed towards negative refraction. These are offered in terms of a novel perspective employing zero- and pole placements in rational functions and analysis of the dielectric function in its complex plane. A number of negative index systems are evaluated including two component media and low gain negative index media. Negative index concepts are introduced to the Electromagnetically Induced Transparency system. A strategy towards design and realization of arbitrary dielectric responses in terms of Krein and Nudel'man causal extrapolation is also presented.
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Davison, M. "Refraction effects in precise surveying measurements." Thesis, University of Nottingham, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.378767.
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Sozou, Peter Demetris. "Studies in optical flow and refraction." Thesis, University of Cambridge, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.320423.
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Cary, Peter William. "Waveform inversion of marine refraction data." Thesis, University of Cambridge, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.330175.
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Peak, Scott Douglas. "Wave refraction over complex nearshore bathymetry." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2004. http://library.nps.navy.mil/uhtbin/hyperion/04Dec%5FPeak.pdf.
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Salomon, Felix. "Refraction index modification by synchrotron radiation." [S.l. : s.n.], 2007. http://nbn-resolving.de/urn:nbn:de:bsz:352-opus-44255.
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Zhang, Jie. "Nonlinear refraction and reflection traveltime tomography." Thesis, Massachusetts Institute of Technology, 1997. http://hdl.handle.net/1721.1/10717.
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Lehman, Joseph Christian. "Sphero-cylindrical Refraction with Spherical Lenses." The Ohio State University, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=osu1587510615809807.
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Oxburgh, Stephen B. "Transforming transformation optics via generalised refraction." Thesis, University of Glasgow, 2016. http://theses.gla.ac.uk/7539/.
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Generalised refraction is a topic which has, thus far, garnered far less attention than it deserves. The purpose of this thesis is to highlight the potential that generalised refraction has to offer with regards to imaging and its application to designing new passive optical devices. Specifically in this thesis we will explore two types of gener- alised refraction which takes place across a planar interface: refraction by generalised confocal lenslet arrays (gCLAs), and refraction by ray-rotation sheets. We will show that the corresponding laws of refraction for these interfaces produce, in general, light-ray fields with non-zero curl, and as such do not have a corresponding outgoing waveform. We will then show that gCLAs perform integral, geometrical imaging, and that this enables them to be considered as approximate realisations of metric tensor interfaces. The concept of piecewise transformation optics will be introduced and we will show that it is possible to use gCLAs along with other optical elements such as lenses to design simple piecewise transformation-optics devices such as invisibility cloaks and insulation windows. Finally, we shall show that ray-rotation sheets can be interpreted as performing geometrical imaging into complex space, and that as a consequence, ray-rotation sheets and gCLAs may in fact be more closely related than first realised. We conclude with a summary of potential future projects which lead naturally from the results of this thesis.
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Ray, Timothy Allen. "Wave propagation over complex bathymetry." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2003. http://library.nps.navy.mil/uhtbin/hyperion-image/03Jun%5FRay.pdf.
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Thesis (M.S. in Physical Oceanography)--Naval Postgraduate School, June 2003.Thesis advisor(s): Thomas H.C. Herbers, Edward B. Thornton. Includes bibliographical references (p. 37). Also available online.
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Carrie, A. L. S. "Wave refraction modelling and longshore sediment transport." Thesis, University of East Anglia, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.372553.
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Wang, Qiang. "Atmospheric refraction and propagation over curved surfaces." n.p, 1997. http://ethos.bl.uk/.
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Wang, Qiang. "Atmospheric refraction and propagation over curved surfaces." Thesis, Open University, 1998. http://oro.open.ac.uk/44453/.
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This thesis presents theoretical and experimental investigations of atmospheric refraction and diffraction of sound over curved surfaces. The main contributions of this work are as follows: The development of an alternative method for calculating the influence of wind on sound propagation in the presence of a ground of finite impedance. The development of numerical models to calculate sound propagation due to monopole and dipole sources over cylindrical or spherical convex and concave surfaces of finite impedance. Laboratory measurements of sound propagation over curved surfaces and comparisons with the proposed theoretical and numerical models. The exploration of the theory for surface wave contributions in an upward refracting atmosphere in the light of obtained experimental data and observation of the surface waves above a convex surface. Experimental and theoretical investigations of the effectiveness of a barrier in the presence of sound speed gradients.
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Etminan, Arvin. "Index of Refraction : Transparent Medium in 3D." Thesis, Luleå tekniska universitet, Institutionen för konst, kommunikation och lärande, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-79111.
Full textAbstract:
Denna uppsats är en beskrivning på utvecklingen av detta projekt, där fokuset handlar om teorier och fakta på ljus i samband med transparanta medium. Målet med projektet var att testa och experimentera inom det nämna området fast i 3D grafik, där resultatet är renderade bilder med analys, diskussioner och slutsatser.This essay describes the development of this project, where the focus is on theories and facts about light and transparent mediums. The aim of the project was to test and experiment the mentioned area in 3D graphics, where the results are single rendered images with analysis, discussions and conclusions.
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Pereira, Tiago José Guardado. "Catarata: expectativas refractivas e visuais." Master's thesis, Faculdade de Ciências Médicas. Universidade Nova de Lisboa, 2008. http://hdl.handle.net/10362/4844.
Full textAbstract:
Este estudo têm como objectivo saber quais as expectativas visuais e refractivas no
pré operatório dos indivíduos com catarata. Analisámos a concordância entre estas e o
resultado final, seis meses após a cirurgia. Foi realizado de forma prospectiva através
de um questionário estruturado, e decorreu no Serviço de Oftalmologia do Hospital
Garcia de Orta E.P.E. Com uma amostra de 200 doentes (68,5% do sexo feminino;
31,5% do sexo masculino, de idades entre os 31 e 89 anos, com uma mediana de 72 anos). A maioria dos indivíduos apresentava um nível escolaridade primário. Não exerciam actividade laboral, 91,5%. Na fase pré-operatória 84,5% dos doentes apresentavam correcção óptica para ver ao longe e 88,0% para ver ao perto. 80,0% dos doentes já conheciam alguém que tinha sido operado a catarata e destes 63,8% estavam satisfeitos com o resultado final. Quando questionados sobre a expectativa de a visão voltar ao normal no pós-operatório, a maioria respondeu com uma expectativa de muito provável (99,5% para respostas iguais ou superiores a 5 na escala de 10 pontos de Likert). 44% dos doentes esperava vir a usar óculos para longe e 46,5% para perto. Na importância de ficar a ver bem sem óculos depois da cirurgia,a maioria respondeu que seria muito importante tanto para ver ao perto (72,5%), como para longe (73,5%), (p=000). 120 pessoas (60%) responderam que “não” à pergunta “Depois da cirurgia à catarata, pensa que vai ficar a ver bem ao perto e ao longe sem precisar de usar óculos”. O género associava-se com esta resposta (p=0,015). De facto, apenas 34% dos indivíduos do sexo feminino é da opinião de que não vai precisar de óculos para a ver bem ao perto e ao longe depois da cirurgia (versus 52,4% para os indivíduos do sexo masculino). No que diz respeito à escolaridade também encontrámos uma associação com significado estatístico (p=0,023). De facto,dos doentes que esperavam não vir a necessitar de usar óculos (para ver ao longe e ao perto), 36,3% nunca estudaram, 40% estudaram até ao ensino primário e 23,8% detinham um nível de escolaridade superior ao ensino primário. A análise e estudo das frequências absolutas sobre a existência de óculos ou compensação refractiva para longe e para perto seis meses após a cirurgia revelou que dos 176 indivíduos (88% da amostra inicial), aproximadamente 89% ficou com óculos para ver ao longe e 92% ficou com óculos para ver ao perto. Da análise exploratória, verificámos que a visão de longe com a melhor correcção óptica, para os casos operados apresenta uma mediana de 8/10 (max.=10/10 e mín.=0,05). A visão de perto com a melhor correcção óptica, para os casos operados apresenta uma mediana de 10/10 (max.=10/10 e mín.=0,05). Verificou-se que a mediana para a acuidade visual de perto é de 5/10 nos casos em que não houve prescrição de óculos e de 10/10 nos casos em que se
verificou prescrição (mín.=0,05 e max.=10/10). Na acuidade visual para longe,
verificámos 19 doentes sem correcção óptica (10,8% do valor total da amostra), no
entanto destes, só sete (4%) atingiram os 10/10 de acuidade visual. A grande maioria
dos doentes (89,2%), ficou com correcção óptica e destes 74 conseguiram uma
acuidade visual de 10/10. Na acuidade visual para perto, verificámos que só 14
doentes ficaram sem correcção óptica (8% do valor total da amostra) e destes só dois,
o correspondente a 1,1% do valor total da amostra conseguiram uma acuidade visual
de 10/10. A grande maioria da amostra, 162 dos casos (89,2%), ficou com correcção
óptica e atingiram os 10/10 de acuidade visual 94 destes casos, o correspondente a
53,4% do valor total da amostra. Verificámos que a expectativa de ficar com óculos
para ver ao longe era muito elevada, tanto para os indivíduos que ficaram sem óculos
como para os que ficaram com óculos (mediana =10 e 9 respectivamente). A
expectativa de ficar com óculos para ver ao perto era muito elevada, tanto para os
indivíduos que ficaram sem óculos como para os que ficaram com óculos a mediana é
igual a 9. De referir, foram poucos os casos em que não foi feita prescrição de óculos,
8% da amostra para n=176, e destes só 21,4% com acuidade visual igual ou superior
a 8/10.
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Mansfeld, Sebastian [Verfasser]. "Spin-Wave Optics: Refraction and Imaging / Sebastian Mansfeld." München : Verlag Dr. Hut, 2012. http://d-nb.info/1028785607/34.
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Otero, Molins Carles. "Lens-based technologies to study accommodation and refraction." Doctoral thesis, Universitat Politècnica de Catalunya, 2018. http://hdl.handle.net/10803/461452.
Full textAbstract:
A visual stimulus can be presented in free space or through lens-based systems. Interestingly, it has been reported many times in the past that some subjects have poorer accommodative responses when optically stimulated, with no aparent reason. However, this limitation has not precluded the use of lens-based systems in ophthalmic devices, virtual reality displays or research setups, probably because it is outweighed by some advantages such as the computer-control of the focal plane of the stimuli. Under this general context, the objective of this thesis is to apply lens-based technologies (from computer-controlled electró-optical lenses to Badal Systems) to study accommodation and refraction.
The methodology of this thesis is structured in 6 studies. The first three studies investigate the response of the accommodative system when optically-stimulated with a Badal optometer. The remaining 3 studies take advantage of electro-optical varifocal systems to investigate new methodologies related to the automated subjective refraction and the accommodative facility test. Concretely, the fourth study is a clinical validation of a new automated refraction algorithm and is the only study thatworks specifically on eye¿s refraction. The fifth and sixth studies use an electro-optical liquid lens to present a repeated step-like stimulus at different accommodative distances. The fifth study validates a new accommodative facility test that integrates both the far and near accommodative facility testwith random changes of accommodative stimulus and, the sixth study explores how the predictability of a stimulus affects the accommodation dynamics.
The results of the first three studies show that previously reported differences in accommodative response when using lens-based methods compared to free space viewing may be explained by the effect of other factors such as the refractive error or field of view rather than the method to stimulate accommodation. It is also shown that the most accurate accommodative responses are obtained for fields between 8º and 10º which suggests that there may be an optimum peripheral retinal image size for accommodation stimulation. Also, it is shown that the only factor that in isolation significantly affects the accuracy of the accommodative responses is the type of refractive error. And finally, it is also shown that the accuracy of the accommodation response generally improves with a 2-dimensional stimulus with apparent depth cues and simulated out-of-focus blur in a relatively large field of view. Even though these conditions may not be adequate for all individuals, they can be used to improve the overall visual comfort in those virtual reality systems that use a varifocal optical system to change the focal plane of a 2-dimensional surface or visual simulators.
The results of the study 4 show the first implementation of a potential novel method of performing non1cycloplegic subjective refraction in adults without clinician suport. Although this method has some limitations thatwarrant further research and it should be tested in a wider population in terms of age4 refraction and different ocular conditions4 it is precise and more accurate than objective refraction methods and it has the potential to be incorporated in novel lens1based technologies to improve primary eye care services in developing countries.
And finally, the last two studies showed also the first implementation of a new accommodative facility test that integrates both the far and near accommodative facility testwith random changes of accommodative stimulus. This new methodology is a faster test than performing both the near and far accommodative tests and it provides more information than conventional accommodative facility tests. Additionally these two studies showed that the prediction operator does not exist in accommodation and the unpredictability of the stimulus does not affect the accommodation dynamics.Un estímul visual es pot presentar a l'espai lliure o a través de sistemes basats en lents. Curiosament, en el passat s'ha reportat moltes vegades que alguns subjectes acomoden de forma més pobre quan aquesta és estimulada per mitjans òptics. Tanmateix, aquesta limitació no ha impedit l'ús de sistemes basats en lents en dispositius oftàlmics, sistemes de realitat virtual o muntatges òptics de recerca, probablement perquè es compensen les limitacions amb alguns avantatges com el control per ordinador del pla focal del estímul. En aquest context general, l'objectiu d'aquesta tesi és aplicar tecnologies basades en lents (des de lents electró-òptiques controlades per ordinador fins a sistemes Badal) per estudiar l'acomodació i refracció. La metodologia d'aquesta tesi està estructurada en 6 estudis. Els primers tres estudis investiguen la resposta del sistema acomodatiu quan està estimulat òpticament amb un optòmetre Badal. Els 3 estudis restants aprofiten els sistemes varifocals electró-òptics per investigar noves metodologies relacionades amb la refracció subjectiva automàtica i la prova de flexibilitat acomodativa. Concretament, el quart estudi és una validació clínica d'un nou algorisme de refracció automatitzat i és l'únic estudi que treballa específicament en la refracció ocular. Els estudis cinquè i sisè utilitzen una lent òptica electró-òptica per presentar un estímul repetit a diferents distàncies acomodatives. El cinquè estudi valida una nova prova híbrida acomodativa que integra la prova de flexibilitat acomodativa llunyana i propera amb canvis aleatoris d'estímul acomodatiu i, el sisè estudi explora com la predictibilitat d'un estímul afecta la dinàmica acomodativa. Els resultats dels tres primers estudis mostren que les diferències reportades anteriorment en la resposta acomodativa quan s'utilitzen mètodes basats en lents en comparació amb la visualització d'estímuls en l'espai lliure es pot explicar per l'efecte de factors com l'error refractiu o el camp de visió més que en el mètode d'estimulació d'acomodació. També es demostra que l'acomodació és més precisa per a camps visuals entre 8 i 10º, el que suggereix que hi pot haver una mida d'imatge retiniana òptima per a l'estimulació de l'acomodació. A més, es demostra que l'únic factor que afecta aïlladament l'exactitud de la resposta acomodativa és el tipus d'error refractiu. També, es demostra que la precisió de la resposta acomodativa generalment millora amb un estímul bidimensional amb pistes de profunditat perifèriques i desenfoc simulat per a un camp de visió relativament gran. Aquestes condicions es poden utilitzar per millorar el confort visual en aquells sistemes de realitat virtual o simuladors visuals que utilitzen un sistema òptic varifocal per canviar el pla focal d'una superfície bidimensional. Els resultats de l'estudi 4 mostren la primera implementació d'un nou mètode potencial per a la realització de refracció subjectiva no cicloplègica en adults sense suport clínic. Encara que aquest mètode requereix encara una investigació addicional en una població més àmplia en termes d'edat, refracció i condicions oculars diferents, és més precís que els mètodes de refracció objectius i té el potencial d'incorporar-se a noves tecnologies basades en lents per millorar els serveis d'atenció primària en països en vies de desenvolupament. Finalment, els dos últims estudis mostren la primera implementació d'una nova prova de flexibilitat acomodativa que integra tant la prova llunyana i propera, amb canvis aleatoris d'estímul acomodatiu. Aquesta nova metodologia és una prova més ràpida que l'execució de les proves d'acomodació pròxima i llunyana i proporciona més informació que les proves de flexibilitat acomodativa per separat. Addicionalment, aquests dos estudis mostren que la capacitat predictiva en l'acomodació es insignificant i que la imprevisibilitat de l'estímul no afecta la dinàmica acomodativa
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Goodwin, Eric Peter. "Dual Interferometer System for Measuring Index of Refraction." Diss., The University of Arizona, 2007. http://hdl.handle.net/10150/195904.
Full textAbstract:
The optical power of a lens is determined by the surface curvature and the refractive index, n. Knowledge of the index is required for accurate lens design models and for examining material variations from sample to sample. The refractive index of glass can be accurately measured using a prism spectrometer, but measuring the index of soft contact lens materials presents many challenges. These materials are non-rigid, thin, and must remain hydrated in a saline solution during testing. Clearly an alternative to a prism spectrometer must be used to accurately measure index.A Dual Interferometer System has been designed, built and characterized as a novel method for measuring the refractive index of transparent optical materials, including soft contact lens materials. The first interferometer is a Low Coherence Interferometer in a Twyman-Green configuration with a scanning reference mirror. The contact lens material sample is placed in a measurement cuvette, where it remains hydrated. By measuring the locations of the multiple optical interfaces, the physical thickness t of the material is measured. A new algorithm has been developed for processing the low coherence signals obtained from the reflection at each optical interface.The second interferometer is a Mach-Zehnder interferometer with a tunable HeNe laser light source. This interferometer measures the optical path length (OPL) of the test sample in the cuvette in transmission as a function of five wavelengths in the visible spectrum. This is done using phase-shifting interferometry. Multiple thickness regions are used to solve 2π phase ambiguities in the OPL.The outputs of the two interferometers are combined to determine the refractive index as a function of wavelength: n(λ) = OPL(λ)/t. Since both t and OPL are measured using a detector array, n is measured at hundreds of thousands of data points. A measurement accuracy of 0.0001 in refractive index is achieved with this new instrument, which is verified using custom glass calibration samples.
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Ward, Dale Michael 1963. "Atmospheric sounding from satellite solar occultation refraction measurements." Diss., The University of Arizona, 1997. http://hdl.handle.net/10150/282495.
Full textAbstract:
Measurements of the refractive bending of solar radiation passing through the limb of the Earth's atmosphere can be utilized to recover vertical profiles of density and temperature. These parameters obtained using the technique of solar refractive sounding could be used to improve satellite solar occultation trace species retrievals and to monitor potential trends in upper atmospheric temperatures. The solar refractive sounding method is described in detail and applied to data available from the Stratospheric Aerosol and Gas Experiment (SAGE II). The meteorological profiles derived from the SAGE II data are not consistently accurate enough for general use due to poor vertical sampling and measurement uncertainties. However, the qualitatively decent results provide optimism for future development and implementation of solar occultation refractive sounders. Better techniques for measuring solar refraction and the potential improvements in the retrievals are also discussed.
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Azzeer, A. M. A. "Some nonlinear laser induced reflection and refraction phenomena." Thesis, Swansea University, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.635819.
Full textAbstract:
This thesis is primarily concerned with some laser-induced nonlinear reflection and refraction phenomena in lithium niobate (LiNbO3) crystals. These are photorefraction and phase conjugation. These phenomena are caused by nonlinear optical processes and the underlying basic theory is presented. A critical review of the theory of phase conjugation by Degenerate Four-Wave Mixing (DFWM) of coherent laser beams is given and an analysis and a simple mathematical description of photorefraction, i.e. light-induced refractive index changes, are presented. Laser beam coupling by two-wave mixing and phase conjugation by four-wave mixing in photorefractive media are discussed in detail. Relevant physical properties of LiNbO3 crystals were measured and are described. An account of the design of experiments and the apparatus used in the present study to investigate photorefraction and phase conjugation in LiNbO3 are presented. The characteristics of the He-Cd laser used in the experimental investigation were measured and are described. Experiments were conducted using two-wave mixing to yield the photorefractive parameters of LiNbO3 which were then used in the interpretation of the experiments in which phase conjugation was observed in DFWM studies. Details of the procedures and the results are given together with estimates obtained for diffusion and photovoltaic field strengths in the conditions used in the present investigation. Photographic evidence of the corrective removal of optical distortion from laser beam propagating through LiNbO3 cyrstal is given.
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Dodd, N. "Parabolic approximations in water wave refraction and diffraction." Thesis, University of Bristol, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.384404.
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Blanchette, Damon Arthur. "Adaptive Spectral Mapping for Real-Time Dispersive Refraction." Digital WPI, 2012. https://digitalcommons.wpi.edu/etd-theses/110.
Full textAbstract:
Spectral rendering, or the synthesis of images by taking into account the wavelengths of light, allows effects otherwise impossible with other methods. One of these effects is dispersion, the phenomenon that creates a rainbow when white light shines through a prism. Spectral rendering has previously remained in the realm of off-line rendering (with a few exceptions) due to the extensive computation required to keep track of individual light wavelengths. Caustics, the focusing and de-focusing of light through a refractive medium, can be interpreted as a special case of dispersion where all the wavelengths travel together. This thesis extends Adaptive Caustic Mapping, a previously proposed caustics mapping algorithm, to handle spectral dispersion. Because ACM can display caustics in real-time, it is quite amenable to be extended to handle the more general case of dispersion. A method is presented that runs in screen-space and is fast enough to display plausible dispersion phenomena in real-time at interactive frame rates.
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Constantinides, Antonios. "Refraction interference elimination employing smart arrays at VHF." Thesis, Middlesex University, 2017. http://eprints.mdx.ac.uk/22243/.
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Radio interference from the Middle East is one of the most significant problems plaguing the local radio services in Cyprus today. The issue is particularly noticeable on the highway, where it affects in-car tuners in all coastal areas of the island when the weather is hot and humid. In this work, the problem of interference from the Middle East was explored in the context of field strength variations versus the type of propagation mechanism favouring the radio waves in Band II, allowing them to travel from the Middle East to beyond the horizon in Cyprus. This problem was significant, since no line of sight exists between the two regions. After in-depth analysis adhering to the ITU (International Telecommunications Union) Recommendations, it was demonstrated that interference is caused by “Tropospheric Ducting”, i.e., trapping of the overseas transmitted signals between two layers of the troposphere at different heights. The upper air data were obtained using the Weather Research Forecasting (WRF-ARW version 3.4) model. The results yielded by the present study confirm that this model provides accurate prediction of interference for up to five days in advance. The interference problem is widely recognized, and therefore many attempts have been made to explicate its causes and provide solutions. The aim of the present study was to present a robust solution based on an innovative receiving antenna design. The antenna is a receiver’s component that collects electromagnetic waves from various directions. The rationale behind focusing on a circular array topology is that its tuning ensures that the receiver processes the desired signal only, while rejecting the unwanted interference. This can presently only be achieved by a large directional external antenna that must be steered mechanically in the desired direction. As this arrangement is not practical, an innovative smart antenna was proposed as an alternative. A circular phased array is a very compact antenna that produces a predicted radiation pattern, whereby it receives maximum energy from the desired direction without the need for mechanical control. Circular arrays exhibit high gain as well as immunity to interference, making them ideal for use in high interference environments. This combination allows the antenna to be incorporated into a commercial deck receiver or installed on vehicles.
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DERROUGH, SAMIR. "Reseaux polymeres interpenetres a gradient d'indice de refraction." Université Louis Pasteur (Strasbourg) (1971-2008), 1993. http://www.theses.fr/1993STR13028.
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L'elaboration d'un materiau a gradient d'indice de refraction (grin), transparent et thermodur, a ete rendue possible par le biais de reseaux polymeres interpenetres (rpi). Un reseau polyurethanne spherique d'indice de refraction 1,5, a ete gonfle par les precurseurs d'un reseau styrenique d'indice de refraction 1,6, que l'on polymerise in situ avant d'avoir atteint l'equilibre de gonflement. La polymerisation des precurseurs du second reseau etant rapide par rapport a leur vitesse de diffusion dans le premier reseau, un gradient d'indice de refraction est obtenu a travers l'echantillon. Au cours de notre etude, nous avons examine les differents parametres susceptibles d'influencer chacune des etapes de la formation du rpi a grin (formation du reseau 1, diffusion des precurseurs du reseau 2, elaboration du reseau 2) pour pouvoir apprehender ses caracteristiques finales. Pour ce qui est de la connaissance de l'evolution de l'indice de refraction au sein de notre materiau, la mise au point de techniques adequates a ete necessaire. Parallelement a cet aspect experimental, nous avons modelise l'augmentation du rayon d'une sphere polyurethanne (pur) en gonflement, ce qui conduit au profil du diffusant a chaque instant. Pour cela, nous avons utilise la theorie de candau qui permet de modeliser les phenomenes de diffusion-gonflement dans un gel. Une bonne concordance entre l'experience et la theorie a ete observee lorsque le pur est synthetise en milieu solvant
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Azadeh, Mohammad. "Reflection and Refraction of Light from Nonlinear Boundaries." PDXScholar, 1994. https://pdxscholar.library.pdx.edu/open_access_etds/4715.
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This thesis deals with the topic of reflection and refraction of light from the boundary of nonlinear materials in general, and saturating amplifiers in particular. We first study some of the basic properties of the light waves in nonlinear materials. We then develop a general formalism to model the reflection and refraction of light with an arbitrary angle of incidence from the boundary of a nonlinear medium. This general formalism is then applied to the case of reflection and refraction from the boundary of linear dielectrics. It will be shown that in this limit, it reduces to the well known Fresnel and Snell's formulas. We also study the interface of a saturating amplifier. The wave equation we use for this purpose is approximate, in the sense that it assumes the amplitude of the wave does not vary significantly in a distance of a wave length. The limits and implications of this approximation are also investigated. We derive expressions for electric field and intensity reflection and transmission coefficients for such materials. In doing so, we make sure that the above mentioned approximation is not violated. These results are compared with the case of reflection and refraction from the interface of a linear dielectric.
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Christiaans, Johan. "Investigation of refraction effects for small GPS networks." Master's thesis, University of Cape Town, 1991. http://hdl.handle.net/11427/18308.
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Using observations from the Global Positioning System (GPS) satellites to determine a three dimensional (3-D) geodetic control network are considered. The repeatability of individual baselines and 3-D vector closures are examined, in order to investigate refraction effects on GPS networks. The effect on GPS baselines of a height bias in the reference point's coordinates is also investigated. A least squares adjustment program is developed and used to obtain a single consistent set of 3-D coordinates for the Tygerberg Test Network (TTN). The results of two GPS processing packages are compared by means of a conformal transformation. It is concluded that single frequency measurements produce better results than the ionospheric free observable on short baselines. Furthermore, a standard atmospheric model shows an improvement over the Marini model to account for tropospheric refraction.
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Wee, Wei Hsiung. "The physics of negative refraction and transformation optics." Thesis, Imperial College London, 2011. http://hdl.handle.net/10044/1/8996.
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Whilst optics is one of the oldest field in science, there are still aspects of electromagnetism that we are only beginning to uncover. For instance, it was demonstrated that materials with simultaneously negative permittivity and permeability exhibit certain exotic behavior; where familiar physical phenomena, such as refraction, are reversed. As such, these materials came to be known as negative refractive index materials (NRIM) and their collective properties as negative refraction. One of the most important and remarkable property of NRIM is perfect lensing - the ability to transport both supra and sub-wavelength optical information from one surface (object plane) to another (image plane), forming images with unprecedented resolution, beyond the diffraction limit. Perfect lensing itself is a consequence of deeper symmetries in electromagnetism, encapsulated in the language of transformation optics - with which we have both a descriptive tool to unify diverse electromagnetic configuarations, as well as a prescriptive tool to design media which bends light at will. While, such transformation medium and NRIM have been demonstrably realised using metamaterials, several challenges remain, of which loss is the major challenge. It is therefore under this trinity of concepts: metamaterials, negative refraction and transformation optics that this thesis is presented. In particular, this thesis illustrates the convergence of the later two concepts, giving rise to a novel class of perfect lens - the compact perfect lens. Here, we shall investigate, their unique properties, construction, challenges, and the dynamics of these lenses. In particular the formulation to study dynamics and effects of losses, is universal; applicable to lenses of any geometry. Finally we shall also propose an alternative universal, top-down approach to overcome losses in perfect lenses using phase conjugation, and demonstrate the capacity of such lenses to see through lossy, translucent obstacles.
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Lee, Jong-Ha. "Study on shallow subsurface imaging using refraction waves." 京都大学 (Kyoto University), 2004. http://hdl.handle.net/2433/145349.
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Schmutz, Myriam. "Apport des methodes geophysiques a la connaissance des glissements-coulees developpes dans les marnes noires. Application a super sauze (alpes de haute provence, france)." Université Louis Pasteur (Strasbourg) (1971-2008), 2000. http://www.theses.fr/2000STR1GE07.
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La recherche s'insere dans le cadre de l'etude des risques naturels et plus specifiquement dans celui de la connaissance precise de la structure de la masse en mouvement. Dans des cas complexes, cette structure n'est pas aisee a definir avec les precisions souhaitees a l'aide des methodes et outils classiquement employes. L'objectif de ce travail est d'etablir un bilan quant a l'apport des methodes geophysiques pour la connaissance de la structure des glissements-coulees developpes dans les manies noires fossilisant un bassin torrentiel constitue d'echines et de ravines, a partir du site de super sauze dans la vallee de barcelonnette (alpes de haute-provence, france). La paleo- topographie ravinee influe fortement sur la direction, l'epaisseur et les caracteristiques hydro- mecaniques desmateriaux de cette coulee,. . . Et donc sur son evolution, dans le temps et dans l'espace, au gre des conditions hydro-climatiques. Les methodes geophysiques employees dans le cadre de cette etude sont l'electrique a courant continu, l'electromagnetisme dans les domaines frequentiel et temporel, ainsi que la sismique refraction, car elles permettent de mettre en evidence des differences de compaction et de resistivite qui sont caracteristiques des parametres pouvant differencier une coulee du substratum. Le principal resultat commun aux diverses methodes geophysiques employees est la validite d'une interpretation 1d lorsque le terrain peut etre considere comme <
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Wei, Tai-Huei. "Nonlinear Optical Absorption and Refraction Study of Metallophthalocyanine Dyes." Thesis, University of North Texas, 1992. https://digital.library.unt.edu/ark:/67531/metadc278287/.
Full textAbstract:
This dissertation deals with the characterization of the nonlinear absorption and refraction of two representative metallophthalocyanine dyes: chloro aluminum phthalocyanine dissolved in methanol, referred to as CAP, and a silicon naphthalocyanine derivative dissolved in toluene, referred to as SiNc. Using the Z-scan technique, the experiments are performed on both the picosecond and nanosecond timescales at a wavelength of 0.532 μm.