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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

Modelování procesu vidění / Modelling of the Visual Perception

Faruga, Michal January 2008 (has links)
This diploma thesis considers with human vision and human eye. It takes into account both anatomic view and physiology standpoints. There is, among others, description of optical processes occurring in the organ of the sight mentioned in the work. The human eye suffers from optical defects – aberrations – that are able to degrade the retinal image and ultimately visual performance. Substantial part of the text deals with these aberrations. There are also analysed possibilities of their elimination using an inverse aberration. Work also assumes opportunity to optical modeling to calculate distorted images from ocular aberration data. Practical part consist of software application created using Matlab environment ver. 6.5 as well as full documentation. The examples of outputs procured using this application are published. Both software application and detail documentation are included on CD.
12

Žmogaus akies dažninės skiriamosios gebos tyrimas / Investigation of the human eye frequency resolution

Vitkauskienė, Rasa 03 November 2011 (has links)
Darbo tema: akies dažninės skiriamosios gebos priklausomybės nuo žiūros kampo tyrimas. Šiame darbe analizuojami akies inertiškumo ypatumai. Išnagrinėta mokslinės literatūros žmogaus regos, akies inertiškumo, akipločio klausimais. Išanalizuota žmogaus regėjimo sistema, regos fiziologija. Pristatoma akies skiriamoji geba, pateikta jos matematinė išraiška, akies inertiškumo pavyzdžiai. Atliktas tyrimas, kurio metu nustatoma akies dažninės skiriamosios gebos priklausomybė nuo žiūros kampo. Tyrime dalyvavo 36 žmonės. Tiriamieji suskirstyti į dvi: 10-25 ir 26-50 metų amžiaus grupes. Tyrime nustatyta, tiriamųjų dažninės skiriamosios gebos priklausomybė nuo žiūros kampo, apskaičiuoti vidutiniai tyrimo duomenų rezultatai, pateikti įvairūs, tyrimo eigoje išryškėję nukrypimai nuo vidurkio. Šie tyrimo duomenys pavaizduoti grafiškai. Analizuojant teorinę medžiagą pastebėta, kad Lietuvoje, tai mažai tyrinėta sritis. Gauti tyrimo rezultatai rodo, kad padarius didesnius, daug daugiau tiriamųjų, kriterijų, apimančius tyrimus, būtų galima gauti įdomių rezultatų. / The subject of the work is the investigation of the dependence of human eye frequency resolution on a viewing angle. The final work analysis the features of eye inertia. Scientific literature was studied to look into the issues of human’s eyesight, eye inertia and the range of vision. The system and physiology of human’s eyesight have been examined as well. The work introduces eye resolution and its mathematical expression, and gives inertia examples. The investigation has been carried out to determine the dependence of human eye frequency resolution on a viewing angle with 36 people participating in it. The people were divided into two groups according to their age: 10-25 and 26-50. The investigation has determined the people’s dependence of eye frequency resolution on a viewing angle. The average data of the results have been estimated and various deviations from the mean shown up during the investigation are graphically presented in the work. While studying the theoretical material it was noticed that this field is still a byway in Lithuania. The findings suggest that if deeper and more criteria spanning researches were carried out, more revealing results could be expected.
13

A FÍSICA DO OLHO HUMANO: UMA PROPOSTA PARA O ENSINO DE ÓPTICA

Santos, Luianne Rodrigues dos 09 February 2018 (has links)
Submitted by MARCIA ROVADOSCHI (marciar@unifra.br) on 2018-08-20T17:34:37Z No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Dissertacao_LuianneRodriguesDosSantos.pdf: 3639379 bytes, checksum: 90ef46662146246ef349b5f5bdcdd2c3 (MD5) / Made available in DSpace on 2018-08-20T17:34:37Z (GMT). No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Dissertacao_LuianneRodriguesDosSantos.pdf: 3639379 bytes, checksum: 90ef46662146246ef349b5f5bdcdd2c3 (MD5) Previous issue date: 2018-02-09 / Society undergoes constant transformations involving cultural, behavioral and intellectual parameters. Thus we consider that the social context is reflected in the educational context. Starting from this research, we look for in the Social Theory (TS) of Zygmunt Bauman, solutions for what Bauman denominates of Liquid Modernity. Bauman's ideas about current society and the derived educational context have met the ideas set forth by David Ausubel in Significant Learning Theory (SAT). This dissertation looked for strategies for the Teaching of Optics, from the Human Eye, for the 9th year of Elementary School. The choice of subject matter was due to the applicability and connection with several areas of knowledge, involving approaches to physics, chemistry, biology and Medicine. We chose to research in the 9th year of elementary school because it was the students' first contact with the Physics discipline. This option allowed a broad approach that will serve as the basis for the content seen at the later levels of education. In search of answers that contribute to a meaningful learning this research carried out a study about the concepts of optics from the Physics of the Human Eye, that uses the Theory of Zygmunt Bauman complemented by Theory of David Ausubel. As an educational product we organized a Learning Unit (AU) composed of seven activities elaborated according to three pedagogical moments (TMP) that sought to verify how the teaching of the concepts of Optics, from the Physics of the Human Eye contribute to learning with meaning to light of TS and TAS. These activities first involved the use of two questionnaires, one oral and another writing that verified the students' previous knowledge and local reality. By sequencing the activities we use didactic resources such as Data show, WEB Searches, Learning Object, Practical Activity, Infographics construction and as synthesis the construction of a RAP. As a result of this dissertation, we have verified that developing teaching strategies that consider the local reality of the student and use new technologies in the teaching of Human Eye Physics contribute to meaningful learning. The students showed interest, curiosity and autonomy in carrying out the activities. / A sociedade passa por constantes transformações que envolvem parâmetros culturais, comportamentais e intelectuais. Assim consideramos que o contexto social é refletido no contexto educacional. Partindo deste elo, buscamos na Teoria Social (TS) de Zygmunt Bauman, soluções para o que Bauman denomina de Modernidade Líquida. As ideias de Bauman sobre a sociedade atual e o contexto educacional derivado, foram ao encontro das ideias estabelecidas por David Ausubel na Teoria da Aprendizagem Significativa (TAS). Esta dissertação buscou estratégias para o Ensino de Óptica, a partir do Olho Humano, para o 9º ano do Ensino Fundamental. A escolha da temática se deu pela aplicabilidade e conexão com diversas áreas do conhecimento, envolvendo abordagens para a física, química, biologia e Medicina. Optamos por pesquisar no 9º ano do ensino fundamental por ser o primeiro contato dos estudantes com a disciplina de Física. Essa opção permitiu uma abordagem ampla que servirá de base para os conteúdos vistos nos níveis posteriores de ensino. Em busca de respostas que contribuam para uma aprendizagem com significado esta pesquisa realizou um estudo acerca dos conceitos de óptica a partir da Física do Olho Humano, que utiliza a Teoria de Zygmunt Bauman complementada pela Teoria de David Ausubel. Como produto educacional organizamos uma Unidade de Aprendizagem (UA) composta por sete atividades elaboradas de acordo com três momentos pedagógicos (TMP) que buscaram verificar como o ensino dos conceitos de Óptica, a partir da Física do Olho Humano contribuem para uma aprendizagem com significado a luz da TS e da TAS. Estas atividades primeiramente envolveram a utilização de dois questionários, um oral e outro escrito que verificou os conhecimentos prévios e a realidade local dos estudantes. Dando sequencia as atividades utilizamos recursos didáticos como Data show, Pesquisas na WEB, Objeto de Aprendizagem, Atividade prática, Construção de infográficos e como síntese a construção de um Rap. Como resultado para esta dissertação, conseguimos verificar que, desenvolver estratégias de ensino que considerem a realidade local do estudante e que utilizem novas tecnologias, no ensino da Física do Olho Humano, contribuem para um aprendizado com significado. Os estudantes demonstraram interesse, curiosidade e autonomia na realização das atividades.
14

Transverse Chromatic Aberration and Vision: Quantification and Impact across the Visual Field

Winter, Simon January 2016 (has links)
The eye is our window to the world. Human vision has therefore been extensively studied over the years. However, in-depth studies are often either limited to our central visual field, or, when extended to the periphery, only correct optical errors related to a narrow spectrum of light. This thesis extends the current knowledge by considering the full visible spectrum over a wide visual field. A broad spectrum means that the wavelength dependence of light propagation inside the eye has to be considered; the optics of the eye will therefore not form a retinal image in the same location for all wavelengths, a phenomenon called chromatic aberration. We present here a new methodology to objectively measure the magnitude of transverse chromatic aberration (TCA) across the visual field of the human eye, and show that the ocular TCA increases linearly with off-axis angle (about 0.21 arcmin per degree for the spectral range from 543 nm to 842 nm). Moreover, we have implemented adaptive psychophysical methods to quantify the impact of TCA on central and peripheral vision. We have found that inducing additional TCA degrades peripheral grating detection acuity more than foveal resolution acuity (more than 0.05 logMAR per arcmin of induced TCA peripherally compared to 0.03 logMAR/arcmin foveally). As stimuli to evaluate peripheral vision, we recommend gratings that are obliquely-oriented relative to the visual field meridian. The results of this thesis have clinical relevance for improving peripheral vision and are equally important for retinal imaging techniques. To limit the negative impacts of TCA on vision, inducing additional TCA should be avoided when the peripheral refractive errors are to be corrected, such as for people suffering from macular degeneration and central visual field loss. In retinal imaging applications, TCA leads to lateral offsets when imaging is performed in more than one wavelength. Consequently, the measurement of TCA together with careful pupil alignment and subsequent compensation can improve the functionality of these instruments. / Ögat är vårt fönster mot världen, och syn har mätts och studerats i stor utsträckning över åren. Trots detta är forskningen om mänsklig syn oftast begränsad till det centrala synfältet, och i studier av det perifera synfältet korrigeras optiska fel endast över ett smalt våglängdsområde. Denna avhandling vidgar forskningen om vår syn till att inkludera hela det synliga spektrumet över ett stort synfält. Ett brett spektrum innebär att vi måste ta hänsyn till våglängdsberoendet i ljusets brytning i ögat; ögats optik kan därför inte avbilda ett objekt till samma bildläge på näthinnan för alla våglängder, ett fenomen som kallas kromatisk aberration. Vi presenterar här en ny metod för att mäta mängden transversell kromatisk aberration (TCA) över ögats synfält och visar att ögats TCA ökar linjärt med vinkeln ut i synfältet (ungefär 0,21 bågminuter per grad från 543 nm till 842 nm). Dessutom har vi implementerat adaptiva psykofysiska mätmetoder för att kvantifiera effekten av TCA på central och perifer syn. Våra resultat visar att extra inducerad TCA påverkar den perifera förmågan att upptäcka sinusformade randmönster mer än den centrala förmågan att upplösa motsvarande ränder (mer än 0,05 logMAR per bågminut inducerad TCA i periferin jämfört med 0,03 logMAR/bågminut centralt). Vid utvärdering av perifer syn rekommenderar vi att använda sinusformade randmönster med en sned riktning jämfört med synfältsmeridianen. Resultaten som presenteras i avhandlingen har klinisk betydelse för att förbättra den perifera synen och är även viktiga för tekniker som avbildar ögats näthinna. För att begränsa den negativa effekt TCA har på synen ska man undvika att inducera extra TCA, t.e.x. när ögats perifera refraktiva fel korrigeras med glasögon för människor med makula degeneration och centralt synfältsbortfall. Vid avbildning av näthinnan ger ögats TCA förskjutningar mellan bilder i olika våglängder. Därför kan mätningar av TCA, tillsammans med välkontrollerad linjering av pupillens position och efterföljande kompensation, förbättra funktionen hos dessa instrument. / <p>QC 20160511</p>
15

SIMULADOR DIDÁTICO DA ACOMODAÇÃO DO OLHO HUMANO

Anselmo, Gustavo Trierveiler 09 September 2016 (has links)
Made available in DSpace on 2017-07-24T19:45:52Z (GMT). No. of bitstreams: 1 Gustavo Trierveiler Anselmo.pdf: 9979848 bytes, checksum: 860bb544a69cc5a636999f5a0f91c142 (MD5) Previous issue date: 2016-09-09 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The Simulator Didactics of Accommodation of the Human Eye is a set of activities that have as objective facilitate the teaching-learning process on optics and, especially, on the process of human accommodation. The educational product explores concepts of geometrical optics (light rays and refraction) in the paraxial approximation and its applications to spherical lenses. Didactic simulator was built with a flexible lens, produced with a latex-made male condom filled with water. Its spherical shape, with a diameter of approximately , was compared with the theoretical model of the “ball lens”. We have experimentally determined its focal length ( and compared it with the corresponding theoretical value, obtaining a accuracy. The flexibility feature of this lens gives the possibility to simulate the accommodation process of the eye in two different situations: for diverging and parallel light beams, corresponding to objects near and far from the observer, respectively. These concepts were addressed in the educational spirit of the meaningful learning of David Ausubel. It has been proposed 4 lesson plans from the previous organizers (taught in 8 lessons), 1 lesson plan for application of the didactic simulator (3 lessons) and 2 meetings for application and discussion of the questionnaires (2 lessons), summing up 13 classes. We have used several resources: lectures, computer simulators, construction of one darkroom, dissection of the bull's-eye and a experimental apparatus produced by students. Adding to other support materials, these instruments facilitated the learning of content offered and the better understanding of the students. This is proven by the results obtained in 42 questionnaires applied. Of these, 24 were before and 18 after the application of the project. There has been an increase of ~200% in the number of hits in the second stage. The proposal has been applied in a class of 39 students, where we had a meaningful learning of over of the class. One should stress also the impact on students, who were more willing to learn, requiring better quality lessons, both in content and evaluation of them. / Esta dissertação descreve um conjunto de atividades realizadas com o objetivo de facilitar o processo de ensino-aprendizagem sobre a óptica e, principalmente, da acomodação do cristalino humano. O produto educacional gerado, chamado de Simulador Didático da Acomodação do Cristalino do Olho Humano, explora conceitos de óptica geométrica (raio de luz e refração) dentro da aproximação paraxial e suas aplicações em lentes esféricas. Para isso foi construído um aparato com uma lente flexível, produzida com preservativo masculino feito de látex preenchido com água. O seu formato esférico, com diâmetro de aproximadamente , foi comparado com o modelo teórico das “ball lens”. Determinamos experimentalmente sua distância focal ( que, comparado com seu valor teórico, tem uma acurácia de . Por ser flexível, foi possível simular o processo de acomodação do cristalino em dois casos: para feixes de luz divergentes e paralelos, simulando situações com objetos próximos e distantes do observador, respectivamente. Estes conceitos foram abordados conforme a concepção educacional da aprendizagem significativa de David Ausubel. Foram propostos quatro planos de aulas de organizadores prévios (ministrado em oito aulas), um plano de aula de aplicação do simulador didático (três aulas) e dois momentos para aplicação e discussão dos questionários (duas aulas), totalizando 13 aulas. Utilizou-se variados recursos: aulas expositivas, simuladores computacionais, construção de câmara escura, dissecação do olho de boi e aparatos experimentais produzidos pelos alunos. Aliados a materiais de apoio, esses instrumentos facilitaram a aprendizagem dos conteúdos ministrados e o melhor entendimento dos alunos. Isso é comprovado pelos resultados obtidos em 42 questionários aplicados. Destes, 24 foram antes e 18 depois da aplicação do projeto. Houve um aumento de ~200% no número de acertos na segunda etapa. A proposta foi aplicada em uma turma de 39 alunos, onde obtivemos uma aprendizagem significativa de mais da classe. A ressaltar, também o impacto nos alunos, que se mostraram mais dispostos a aprenderem, exigindo aulas de melhor qualidade, tanto na exposição do conteúdo como na avaliação.
16

A Fully Customizable Anatomically Correct Model of the Crystalline Lens

Wilson, Cynthia Nicole 04 August 2011 (has links)
The human eye is a complex optical system comprised of many components. The crystalline lens, an optical component with a gradient index (GRIN), is perhaps the least understood as it is situated inside the eye and as a result is difficult to characterize. Its complex nonlinear structure is not easily measured and consequently not easily modeled. Presently several models of the GRIN structure exist describing the average performance of crystalline lenses. These models, however, do not accurately describe the performance of crystalline lenses on an individual basis and a more accurate individual eye model based on anatomical parameters is needed. This thesis proposes an anatomically correct, individually customizable crystalline lens model. This is an important tool and is needed both for research on the optical properties of human eyes and to diagnose and plan the treatment of optically based visual problems, such as refractive surgery planning. The lens model consisted of an interior GRIN with a constant refractive index core. The anterior and posterior surface was described by conic sections. To realize this eye model, the optical and biometric properties of mammalian lenses were measured and the correlation relationships between these measurements were used to simplify the model down to one fitting parameter which controls the shape of the GRIN. Using this data, an anatomically correct individualizable model of the lens was successfully realized with varying parameters unique to each lens. Using this customizable lens model, customizable human eye models based on measurements of the entire human eye can be realized.
17

A Fully Customizable Anatomically Correct Model of the Crystalline Lens

Wilson, Cynthia Nicole 04 August 2011 (has links)
The human eye is a complex optical system comprised of many components. The crystalline lens, an optical component with a gradient index (GRIN), is perhaps the least understood as it is situated inside the eye and as a result is difficult to characterize. Its complex nonlinear structure is not easily measured and consequently not easily modeled. Presently several models of the GRIN structure exist describing the average performance of crystalline lenses. These models, however, do not accurately describe the performance of crystalline lenses on an individual basis and a more accurate individual eye model based on anatomical parameters is needed. This thesis proposes an anatomically correct, individually customizable crystalline lens model. This is an important tool and is needed both for research on the optical properties of human eyes and to diagnose and plan the treatment of optically based visual problems, such as refractive surgery planning. The lens model consisted of an interior GRIN with a constant refractive index core. The anterior and posterior surface was described by conic sections. To realize this eye model, the optical and biometric properties of mammalian lenses were measured and the correlation relationships between these measurements were used to simplify the model down to one fitting parameter which controls the shape of the GRIN. Using this data, an anatomically correct individualizable model of the lens was successfully realized with varying parameters unique to each lens. Using this customizable lens model, customizable human eye models based on measurements of the entire human eye can be realized.
18

Desarrollo de un Simulador Visual de Óptica Adaptativa para el Diseño Interactivo de Componentes Oftálmicos

Manzanera Román, Silvestre 04 December 2006 (has links)
En este trabajo se describe un simulador visual de óptica adaptativa (SVOA) empleado con dos objetivos: primero, el testeo y diseño de perfiles de fase progresivos para extender la profundidad de foco y segundo el estudio del efecto de la aberración cromática longitudinal y su acoplamiento con la aberración esférica en el ojo humano.Diversos perfiles de fase progresivos fueron analizados en el SVOA, resultando un excelente acuerdo con las simulaciones teóricas. Algunos de estos perfiles fueron implementados físicamente en lentes de contacto y evaluados visualmente. La buena concordancia que se encontró entre esta evaluación y la obtenida simulando el perfil con el SVOA validan todo el procedimiento y el sistema.También se llevaron a cabo medidas de la capacidad visual combinando la corrección de las aberraciones cromática y esférica. Los resultados indican que la mejor calidad de visión se produce al eliminar al mismo tiempo ambas aberraciones. / An adaptive optics visual simulator (AOVS) is described in this work. It was used to test and design progressive phase profiles to extend depth of focus, and to study the combined effect of both, the longitudinal chromatic aberration and the spherical aberration in the human eye.A set of progressive phase profiles were tested using the AOVS, obtaining an excellent agreement with the theoretical simulations. Some of these phase profiles were implemented on contact lenses and visually tested. Again the results agreed with the evaluation carried out through the AOVS, validating the instrument.Visual performance was also tested correcting either chromatic aberration or spherical aberration or both, resulting the best performance when both aberrations are simultaneously corrected.
19

A Fully Customizable Anatomically Correct Model of the Crystalline Lens

Wilson, Cynthia Nicole 04 August 2011 (has links)
The human eye is a complex optical system comprised of many components. The crystalline lens, an optical component with a gradient index (GRIN), is perhaps the least understood as it is situated inside the eye and as a result is difficult to characterize. Its complex nonlinear structure is not easily measured and consequently not easily modeled. Presently several models of the GRIN structure exist describing the average performance of crystalline lenses. These models, however, do not accurately describe the performance of crystalline lenses on an individual basis and a more accurate individual eye model based on anatomical parameters is needed. This thesis proposes an anatomically correct, individually customizable crystalline lens model. This is an important tool and is needed both for research on the optical properties of human eyes and to diagnose and plan the treatment of optically based visual problems, such as refractive surgery planning. The lens model consisted of an interior GRIN with a constant refractive index core. The anterior and posterior surface was described by conic sections. To realize this eye model, the optical and biometric properties of mammalian lenses were measured and the correlation relationships between these measurements were used to simplify the model down to one fitting parameter which controls the shape of the GRIN. Using this data, an anatomically correct individualizable model of the lens was successfully realized with varying parameters unique to each lens. Using this customizable lens model, customizable human eye models based on measurements of the entire human eye can be realized.
20

A Fully Customizable Anatomically Correct Model of the Crystalline Lens

Wilson, Cynthia Nicole January 2011 (has links)
The human eye is a complex optical system comprised of many components. The crystalline lens, an optical component with a gradient index (GRIN), is perhaps the least understood as it is situated inside the eye and as a result is difficult to characterize. Its complex nonlinear structure is not easily measured and consequently not easily modeled. Presently several models of the GRIN structure exist describing the average performance of crystalline lenses. These models, however, do not accurately describe the performance of crystalline lenses on an individual basis and a more accurate individual eye model based on anatomical parameters is needed. This thesis proposes an anatomically correct, individually customizable crystalline lens model. This is an important tool and is needed both for research on the optical properties of human eyes and to diagnose and plan the treatment of optically based visual problems, such as refractive surgery planning. The lens model consisted of an interior GRIN with a constant refractive index core. The anterior and posterior surface was described by conic sections. To realize this eye model, the optical and biometric properties of mammalian lenses were measured and the correlation relationships between these measurements were used to simplify the model down to one fitting parameter which controls the shape of the GRIN. Using this data, an anatomically correct individualizable model of the lens was successfully realized with varying parameters unique to each lens. Using this customizable lens model, customizable human eye models based on measurements of the entire human eye can be realized.

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