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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.
161

Remote Imaging System Acquisition Multispectral Imager

Choate, Laura, Lundstrom, Kevin, Pounds, Kevin, Richards, Garrett, Vinal, Eli 10 1900 (has links)
ITC/USA 2011 Conference Proceedings / The Forty-Seventh Annual International Telemetering Conference and Technical Exhibition / October 24-27, 2011 / Bally's Las Vegas, Las Vegas, Nevada / The National Aeronautics and Space Administration's (NASA) Remote Imaging System Acquisition (RISA) camera will integrate the functionalities of existing space cameras. The system operates between 350nm and 1050nm wavelengths, with a MATLAB user interface, uses a CS-mount standard with a CMOS detector, and has a fixed focal plane. The implementation of a liquid lens uses electrical focus adjustments to image from infinity down to one foot. This will allow wireless operation and reduces mechanical failure. All images and video captured will be transmitted wirelessly to a MATLAB program. This data is then processed and stored, allowing for remote imaging.
162

Improved designs for future thermal imagers

Ibrahim, Hassan January 2000 (has links)
No description available.
163

Lysozyme Deposition Studies on Silicone Hydrogel Contact Lens Materials

Nagapatnam Subbaraman, Lakshman January 2005 (has links)
Over 60 proteins have been detected in the tear film and among these lysozyme has attracted the greatest attention. Several techniques for elucidating the identity, quantity and conformation of lysozyme deposited on soft contact lenses have been developed. Lysozyme also deposits on the newly introduced silicone hydrogel (SH) lens materials, but in extremely low levels compared to conventional hydrogel lenses. Hence, a major analytical complication with the study of the SH contact lens materials relates to the minute quantity of deposited lysozyme. The first project of this thesis involved the development of a method whereby lysozyme mass extracted from SH lens materials would be preserved over time and would be compatible with an optimized Western blotting procedure. This methodological development was incorporated into a clinical study (CLENS-100?? and Silicone Hydrogels ? CLASH study) wherein the difference in the degree of total protein, the difference in lysozyme deposition and activity recovered from lotrafilcon A SH lens material when subjects used surfactant containing rewetting drops (CLENS-100??) versus control saline was investigated. The remaining experiments were in vitro experiments wherein the lenses were doped in artificial lysozyme solution containing <sup>125</sup>I-labeled lysozyme. These experiments were performed to gain insight into the kinetics of lysozyme deposition on SH lens materials and also the efficacy of a reagent in extracting lysozyme from SH lens materials. A protocol was developed whereby the percentage loss of lysozyme mass found on lotrafilcon A SH lenses was reduced from approximately 33% to <1% (p<0. 001), following extraction and resuspension. The results from the CLASH study demonstrated that when subjects used a surfactant containing rewetting drop instead of a control saline drop total protein deposition (1. 2??0. 7 ??g/lens versus 1. 9??0. 8 ??g/lens, p<0. 001), lysozyme deposition (0. 7??0. 5 ??g/lens versus 1. 1??0. 7 ??g/lens, p<0. 001) and percentage lysozyme denaturation (76??10% versus 85??7%, p=0. 002) were all reduced. The results from the kinetics study demonstrated that lysozyme accumulated rapidly on etafilcon A lenses (1 hr, 98??8 ??g/lens), reached a maximum on the 7th day (1386??21 ??g/lens) and then reached a plateau (p=NS). Lysozyme accumulation on FDA Group II and SH lenses continued to increase across all time periods, with no plateau being observed (p<0. 001). The results from the extraction efficiency study showed that 0. 2% trifluoroacetic acid/ acetonitrile was 98. 3??1. 1% and 91. 4??1. 4% efficient in extracting lysozyme deposited on etafilcon A and galyfilcon lenses, while the lysozyme extraction efficiency was 66. 3??5. 3 % and 56. 7??3. 8% for lotrafilcon A and balafilcon lens materials (p<0. 001). The results from these studies re-emphasize that novel SH lens materials are highly resistant to protein deposition and demonstrate high levels of biocompatibility.
164

The role of aberrations in the relative illumination of a lens system

Reshidko, Dmitry, Sasian, Jose 01 October 2016 (has links)
Several factors impact the light irradiance and relative illumination produced by a lens system at its image plane. In addition to the cosine-fourth-power radiometric law, image and pupil aberrations, and light vignetting also count. In this paper, we use an irradiance transport equation to derive a closed form solution that provides insight into how individual aberration terms affect the light irradiance and relative illumination. The theoretical results are in agreement with real ray tracing.
165

Dual interferometer for dynamic measurement of corneal topography

Micali, Jason D., Greivenkamp, John E. 31 August 2016 (has links)
The cornea is the anterior most surface of the eye and plays a critical role in vision. A thin fluid layer, the tear film, coats the outer surface of the cornea and serves to protect, nourish, and lubricate the cornea. At the same time, the tear film is responsible for creating a smooth continuous surface, where the majority of refraction takes place in the eye. A significant component of vision quality is determined by the shape of the cornea and stability of the tear film. A dual interferometer system for measuring the dynamic corneal topography is designed, built, verified, and qualified by testing on human subjects. The system consists of two coaligned simultaneous phase-shifting polarization-splitting Twyman-Green interferometers. The primary interferometer measures the surface of the tear film while the secondary interferometer tracks the absolute position of the cornea, which provides enough information to reconstruct the absolute shape of the cornea. The results are high-resolution and high-accuracy surface topography measurements of the in vivo tear film and cornea that are captured at standard camera frame rates. (C) 2016 Society of Photo-Optical Instrumentation Engineers (SPIE)
166

TWO-SURFACE OPTICAL SYSTEMS WITH ZERO THIRD-ORDER SPHERICAL ABERRATION

Stavroudis, O. N. 15 April 1969 (has links)
QC 351 A7 no. 37 / This paper derives four one-parameter families of two-surface optical systems having the property that, relative to a well-defined pair of conjugate points, one finite and the other infinite, third-order spherical aberration is zero. The two surfaces can be either refracting or reflecting. Aperture planes are defined for which third-order astigmatism is zero. An expression for coma is also derived. Assuming that the systems will be constructible, a means of defining domains for the free parameter is indicated. Possible applications of these results to optical design are included.
167

PROBLEMS IN NULL CORRECTOR DESIGN

Lytle, John D. 25 April 1969 (has links)
QC 351 A7 no. 39 / Optical systems known as "null correctors" are often required to test certain aspheric optical surfaces. This report classifies these systems on the basis of their first -order geometry and analyzes the merits of each type. The behavior of optical aberrations, especially spherical aberration, in these systems is examined in the context of computer optimization techniques, particular attention being given to some design problems unique to null correcting systems. Orthonormal concepts are applied to the problem of reducing spherical aberration in null correctors. It is shown that exceedingly simple merit functions may be constructed to streamline the optimization process. These merit functions are composed of simple linear sums of the angular spherical aberration coefficients B1, B3, B5, and B7. Thus, minimizing the following sums will improve nearly diffraction - limited systems: ( - 13 B1 + 1 B3 - g' B5 - B7) , ( 4.131 - B3 - B5) , ( - 2B1 - B3) , and ( - B1) /1-5- 3/7 3 or ( 120 B3 + 960 B5 + 840 B7 ) , ( 840 B5 + 2520 B7) , and ( 840 B7) Non -diffraction - limited systems may be optimized by minimizing the sums ( 6 B3 + 5 B5 + 5 B7) , ( p B5 + 3 B7) , and ( 1 0 B7) To demonstrate the effectiveness of the techniques discussed, the process of designing a specific null correcting system is followed in detail.
168

Role of aberrations in the relative illumination of a lens system

Reshidko, Dmitry, Sasian, Jose 29 November 2016 (has links)
Several factors impact the light irradiance and relative illumination produced by a lens system at its image plane. In addition to cosine-fourth-power radiometric law, image and pupil aberrations and light vignetting also count. We use an irradiance transport equation to derive a closed form solution that provides insight into how individual aberration terms affect the light irradiance and relative illumination. The theoretical results are in agreement with real ray tracing. (C) 2016 Society of Photo-Optical Instrumentation Engineers (SPIE)
169

Untersuchung der postoperativen Komplikationen bei skleranahtfixierter Kunstlinsenimplantation / Complications in sutured scleral fixation of artificial lens implantation

Brandt, Lisa 22 May 2019 (has links)
No description available.
170

Comparação da função visual entre pacientes implantados com lentes intraoculares para a correção da presbiopia após a facoemulsificação / Comparison of visual function in patients implanted with intraocular lenses to correct presbyopia after phacoemulsification

Ferreira, Miriam Alves 14 June 2018 (has links)
Objetivo: Estudar maneiras distintas de se corrigir a presbiopia durante a facoemulsificação, através da avaliação do desempenho visual de quatro diferentes modelos de lentes intraoculares; assim como determinar a influência da pupila na recuperação visual e comparar a independência ao uso de óculos após o implante bilateral. Casuística e Métodos: Estudo prospectivo, consecutivo, randomizado que avaliou 60 pacientes (120 olhos) divididos em quatro grupos: lentes multifocais Restor +3, Restor +2.5, monovisão com a lente SN60WF e a pseudoacomodativa Crystalens XO. Foram incluídos pacientes que apresentavam catarata nuclear NI, NII ou cortical similar, que foram submetidos à avaliação oftalmológica completa no pré- operatório e com 1, 3 e 12 meses após a cirurgia. Antes do procedimento, os seguintes exames foram realizados: biometria óptica (Lenstar 900), microscopia especular, avaliação da região macular e das camadas de fibras nervosas por meio de Tomografia de Coerência Óptica (OCT), avaliação da sensibilidade ao contraste (Software Macular Mapping Test) e pupilometria dinâmica (ISCAN INC). As cirurgias foram realizadas por dois cirurgiões, em caráter ambulatorial. Durante o seguimento, nas visitas de 1, 3 e 12 meses após a cirurgia, foram realizadas medidas de acuidade visual longe e perto, mono e binocular, curva de desfoco monocular e pupilometria; e foi aplicado um questionário de satisfação baseado do Visual Functioning Questionnaire - 25 (VFQ 25), assim como medidas de sensibilidade ao contraste. Resultados: Dos 120 olhos selecionados, 114 foram operados, 106 avaliados com um mês de cirurgia, 100 com três meses e 45 pacientes (90 olhos) chegaram a última avaliação com um ano de follow-up. As médias da acuidade visual para longe sem correção binocular foram de 0,09 ± 0,04; 0,09 ± 0,03 e 0,11 ± 0,03 logMar para as lentes Restor +2.5, Restor +3 e SN60WF, respectivamente. Entre elas não se observou diferença significativa. Já para a lente Crystalens XO, a média foi de 0,24 ± 0,04 logMar, constatando-se sua inferioridade para longe de forma significativa estatisticamente em relação às demais. Este resultado foi atribuído à pobre previsibilidade refracional da lente pseudoacomodativa (-1.33 ± 1.37 dpt). Para perto, não houve diferença entre os grupos Restor +3 e monovisão, e as lentes Restor +2.5 e Crystalens apresentaram piores resultados que as duas primeiras, de forma significativa. As médias para perto, em logMar foram de 0,08 ± 0,01; 0,17 ± 0,04; 0,22 ± 0,04 e 0,23 ± 0,07 para as lentes Restor +3, SN60WF, Restor +2.5 e Crystalens, respecivamente. A curva de desfoco das lentes multifocais Restor +3 e Restor +2.5 apresentou dois picos de acuidade visual máxima; o primeiro vértice próximo a zero e o segundo em -2.5 dpt para a Restor +3 e -2 dpt para a Restor +2.5. O segundo vértice da Restor +3 foi mais acentuado em relação ao da Restor +2.5. Já o modelo Crystalens apresentou a curva de desfoco com um pico de acuidade visual máxima, semelhante às lentes monofocais SN60WF, ambas com vértice próximo ao equivalente esférico programado. A partir da curva de desfoco, somando-se as acuidades visuais entre os dois picos de melhor visão, foi criado um índice, denominado Índice de Multifocalidade. O intuito foi criar um indicador de qualidade de visão longe, intermediário e perto para as diversas lentes. O modelo Restor +3 obteve o melhorResumo índice entre as lentes estudadas, porém não mostrou diferença significativa em relação à Restor +2.5, que, por sua vez, não evidenciou diferença quanto à Crystalens. A lente SN60WF teve o pior índice. Já em relação a pupila, não houve interferência de sua amplitude de contração no pré-operatório com as acuidades visuais longe e perto após a cirurgia. Contudo, o tamanho da pupila contraída demonstrou correlação com o índice de multifocalidade. A avaliação da sensibilidade a estímulos de baixo contraste (10%) no campo visual central (8 graus) não foi diferente entre os grupos, tanto no pré quanto no pós-operatório. E em relação à presença de halos e glare, os grupos Restor +3 e +2.5 apresentaram incidência de 26% e 43%, respectivamente; já no grupo SN60WF não houve relato. A satisfação com a performance visual para longe foi de 78% no grupo Crystalens, 80% no grupo monovisão e 90% para as multifocais Restor +3 e Restor +2.5. Para perto, 100 % dos usuários da Restor +3, 80% da monovisão, e 50% dos grupos Restor +2.5 e Crystalens estavam satisfeitos. Finalmente, entre as maneiras distintas de se corrigir a presbiopia na facoemulsificação, o grupo Restor +3 atingiu 93% de independência do uso de óculos após a cirurgia. Inesperadamente e de acordo com os resultados, o modelo Restor +2.5 demonstrou baixa probabilidade de independência (14%). Para a monovisão e Crystalens, 30% e 50%, respectivamente. Conclusões: Tanto a lente multifocal Restor +3 quanto a monovisão com a SN60WF foram eficazes de forma semelhante na correção da presbiopia, porém o modelo Restor +3 proporcionou maior probabilidade de independência ao uso de óculos. Os modelos Restor +2.5 e a Crystalens XO pseudoacomodativa foram inferiores que as duas primeiras, pela lente multifocal Restor +2.5 apresentar resultados aquém do previsto para perto, com baixa independência do uso de óculos; e a Crystalens mostrar imprevisibilidade refracional biométrica, comprometendo a visão de longe dos usuários. A respeito da dinâmica pupilar, as medidas do pré e pós-operatório não evidenciaram interferência no desempenho visual das lentes multifocais, monovisão e pseudoacomodativa; exceto no índice de multifocalidade, onde as pupilas contraídas apresentaram correlação com os resultados. / Objective: Study different ways of correcting presbyopia in phacoemulsification by comparing visual performance of four different models of intraocular lenses; as well as to determine the influence of the pupil on visual recovery and to compare the independence of glasses after bilateral implant. Casuistic and Methods: Prospective, consecutive, randomized study with 60 patients (120 eyes) divided into 4 groups: Restor +3 and Restor +2.5 multifocal lenses, monovision with SN60WF and Crystalens XO pseudoacommodative lens. Patients who had nuclear NI, NII or similar cortical cataract were submitted to a complete ophthalmologic evaluation in the preoperative period and at 1,3 and 12 months after surgery. Before procedure, the following tests were performed: optical biometry (Lenstar 900), specular microscopy, analyse of macular region and nerve fiber layers with Optical Coherence Tomography (OCT), contrast sensitivity (MMTest Software) and pupilometry dynamics (ISCAN INC). Surgeries were performed by two surgeons. During the follow-up, visits of 1, 3 and 12 months were measured far and near, mono and binocular visual acuity, defocous curve, pupilometry, satisfaction questionnaire was applied based on Visual Functioning Questionnaire - 25 (VFQ 25) as well as a contrast sensitivity measurements (Macular Mapping Test). Results: Of the 120 eyes selected, 114 were operated, 106 were evaluated at 1 month of surgery, 100 at 3 months, and 45 pacients (90 eyes) achieve the last evaluation at 1 year follow-up. The mean visual acuity for far without binocular correction was 0.09 ± 0.04; 0.09 ± 0.03 and 0.11 ± 0.03 logMar for the lenses Restor +2.5, Restor +3 and SN60WF respectively. Between them there was no difference. For the Crystalens XO lens, the mean was 0.24 ± 0.04 logMar, showing its inferiority statistically significantly different than the others. This result was attributed by the poor refractive predictability of the pseudoacommodative lens (-1.33 ± 1.37 dpt). For close, there was no difference between the Restor +3 and monovision groups, and the Restor +2.5 and Crystalens lenses were worse than the first with statistical significance . The means for near were 0,08 ± 0,01; 0.17 ± 0.04; 0.22 ± 0.04 and 0.23 ± 0.07 for the Restor +3, SN60WF-, Restor +2.5 and Crystalens lenses. The defocous curve of the multifocal lenses Restor +3 and Restor +2.5 had 2 peaks of maximum visual acuity, the first in zero and the second close to -2.5 dpt for Restor +3 and -2 dpt for Restor +2.5. The second vertex of Restor +3 was more pronounced than Restor +2.5. The Crystalens group presented a defocous curve with only 1 peak of maximum visual acuity, as well as the SN60WF monofocal lenses, both with a vertex near the programmed spherical equivalent. From the defocous curve, adding the visual acuity between the two best view peaks, an index was created, called Multifocality Index. The aim was to create a far, intermediate and close quality index for the various lenses. Restor +3 obtained the best index, but that was no significantly different than Restor +2.5, which had no difference with Crystalens. SN60WF achieved the worst index. Regarding the pupil, did no notice interference of its preoperative contraction amplitude with the visual acuities far and near after the surgery. However, the size of contracted pupil had a statistically significant correlation with the multifocality index. The sensitivity to low contrastAbstract stimuli (10%) in the central visual field (8 degrees) was no different between the groups, both in the pre and postoperative periods. About presence of halos and glare, the multifocal lenses Restor +3 and Restor +2.5 showed 26% and 43% respectively. No cases were reportaded with model SN60WF. The satisfaction with the far visual performance was 78% in the Crystalens group, 80% for monovision and 90% in the multifocal lenses Restor +3 and +2.5. For near, 100% of Restor +3 users, 80% of monovision, and 50% of Restor +2.5 and Crystalens groups were satisfied. Finally, among the distinct ways of correcting presbyopia in phacoemulsification, the Restor +3 group showed that 93% of their users achieved independence of the glasses after surgery. Unexpectedly and according to the visual results, the Restor +2.5 model showed a low probability of independence, 14%. For monovision and Crystalens, 30% and 50% respectively. Conclusions: Both Restor +3 and monovision with SN60WF were similarly effective for correction of presbyopia, but the Restor +3 model provides a greater probability of independence from wearing glasses. The Restor +2.5 and pseudoacommodative models Crystalens XO were worst than the first two, because the multifocal Restor +2.5 presented results below the predicted for near, with low independence of the use of glasses; and model Crystalens unexpected biometric refractive unpredictability, compromising the view from far away from users. Regarding the pupillary dynamics, the pre and postoperative measurements showed no interference in the visual performance of multifocal, monovision and pseudoacommodative lenses; except in the multifocality index, where pupils contracted had a correlation with the results.

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