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Dissertations / Theses on the topic 'Optical instruments'
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Zhang, Hongping. "Image quality metrics for visual optical Instruments /." Online version of thesis, 1991. http://hdl.handle.net/1850/11217.
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Baumhammer, Megan. "Optical Instruments and the Early Modern Imagination." Thesis, The University of Sydney, 2013. http://hdl.handle.net/2123/11708.
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This thesis recontextualizes seventeenth century instruments. I explore their meaning through the ways in which they were discussed and thought about in contemporary texts, both scientific and literary: the imaginative treatment of the telescope through Kepler’s 1610 work Dissertatio cum Nuncio Sidereo and Milton’s Paradise Lost (1667); the microscope through Hooke’s Micrographia (1665). I pay particular attention to the role that the interaction between text and image has in the creation of meaning in this key work of the Royal Society. I argue that these instruments of the seventeenth century had a specific role to play in the imagination of the time: that optical instruments and the view through them enabled those who used them, and read about them, to imagine in new ways. The instruments became metaphors for seeing more clearly, more deeply, or further. However, the telescope has entered the cultural imagination about the early modern period in a unique and different way. For critics of modernity such as Arendt or Heidegger, instruments are integral to a disenchantment narrative of modernity. Far from alienating or estranging the human observer, I show that for these authors in the seventeenth century the imagination was central to the understanding of instruments and their use, and they, on their part, came to enhance and reshape it.
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Lloyd-Hart, Michael. "Novel techniques of wavefront sensing for adaptive optics with array telescopes using an artificial neural network." Diss., The University of Arizona, 1992. http://hdl.handle.net/10150/185749.
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Atmospheric turbulence causes severe degradation of the resolving and signal-to-noise properties of present optical telescopes. Diffraction-limited resolution can be recovered through the use of a deformable ('adaptive') optical element to correct the atmospheric wavefront error. An adaptive optics system operating in the near infrared (1.7 - 3.5 μm) has been developed for use at the Multiple Mirror Telescope (MMT), an array of six co-mounted 1.8 m telescopes, in which six flat mirrors are used to correct the wavefront tilt across each aperture, and the phase differences between apertures. This can reduce the error sufficiently to achieve a diffraction-limited image with a central peak of 0.06 arcseconds full width at half maximum at 2.2 μm wavelength. A number of algorithms are used to drive the adaptive mirror in a closed servo loop, including a trained artificial neural network which deduces the wavefront aberration from a pair of simultaneous in- and out-of-focus images of a star, taken at the combined focal plane of the telescope. Computer simulations have shown that the net is capable of deriving the wavefront for the full six-mirror aperture, and in practice, the net has been demonstrated in the lab to maintain two- and three-aperture diffraction-limited beam profiles in the presence of distorting effects. On the sky, with a real star, the net has successfully restored the diffraction limit for two adjacent MMT segments. High resolution images have been obtained of various objects with a wide-field camera looking in the field around the wavefront reference star. Work has also been carried out to characterise the wavefront aberration at the MMT, which confirms the Kolmogorov model of turbulence. Finally, a new algorithm is discussed which shows great promise for correction of phase errors in array telescopes.
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Moneyhun, Sara E. "Optical pyrometry for noncontact temperature measurement." Thesis, This resource online, 1990. http://scholar.lib.vt.edu/theses/available/etd-01262010-020330/.
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Jackson, Joshua D. "Optical vehicular tracking system." Birmingham, Ala. : University of Alabama at Birmingham, 2009. https://www.mhsl.uab.edu/dt/2009p/jackson.pdf.
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Thesis (Ph. D.)--University of Alabama at Birmingham, 2009.Additional advisors: Thomas C. Jannett, David Pan, Gregg L. Vaughn, Percy F. Wang. Description based on contents viewed June 2, 2009; title from PDF t.p. Includes bibliographical references (p. 69-72).
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Avramidis, Stefanos. "Simulation and parameter estimation of spectrophotometric instruments ." Thesis, KTH, Numerical Analysis and Computer Science, NADA, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-12292.
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The paper and the graphics industries use two instruments with different optical geometry (d/0 and 45/0) to measure the quality of paper prints. The instruments have been reported to yield incompatible measurements and even rank samples differently in some cases, causing communication problems between these sectors of industry.A preliminary investigation concluded that the inter-instrument difference could be significantly influenced by external factors (background, calibration, heterogeneity of the medium). A simple methodology for eliminating these external factors and thereby minimizing the instrument differences has been derived. The measurements showed that, when the external factors are eliminated, and there is no fluorescence or gloss influence, the inter-instrument difference becomes small, depends on the instrument geometry, and varies systematically with the scattering, absorption, and transmittance properties of the sample.A detailed description of the impact of the geometry on the results has been presented regarding a large sample range. Simulations with the radiative transfer model DORT2002 showed that the instruments measurements follow the physical radiative transfer model except in cases of samples with extreme properties. The conclusion is that the physical explanation of the geometrical inter-instrument differences is based on the different degree of light permeation from the two geometries, which eventually results in a different degree of influence from near-surface bulk scattering. It was also shown that the d/0 instrument fulfils the assumptions of a diffuse field of reflected light from the medium only for samples that resemble the perfect diffuser but it yields an anisotropic field of reflected light when there is significant absorption or transmittance. In the latter case, the 45/0 proves to be less anisotropic than the d/0.In the process, the computational performance of the DORT2002 has been significantly improved. After the modification of the DORT2002 in order to include the 45/0 geometry, the Gauss-Newton optimization algorithm for the solution of the inverse problem was qualified as the most appropriate one, after testing different optimization methods for performance, stability and accuracy. Finally, a new homotopic initial-value algorithm for routine tasks (spectral calculations) was introduced, which resulted in a further three-fold speedup of the whole algorithm.The paper and the graphics industries use two instruments with different optical geometry (d/0 and 45/0) to measure the quality of paper prints. The instruments have been reported to yield incompatible measurements and even rank samples differently in some cases, causing communication problems between these sectors of industry.A preliminary investigation concluded that the inter-instrument difference could be significantly influenced by external factors (background, calibration, heterogeneity of the medium). A simple methodology for eliminating these external factors and thereby minimizing the instrument differences has been derived. The measurements showed that, when the external factors are eliminated, and there is no fluorescence or gloss influence, the inter-instrument difference becomes small, depends on the instrument geometry, and varies systematically with the scattering, absorption, and transmittance properties of the sample.A detailed description of the impact of the geometry on the results has been presented regarding a large sample range. Simulations with the radiative transfer model DORT2002 showed that the instruments measurements follow the physical radiative transfer model except in cases of samples with extreme properties. The conclusion is that the physical explanation of the geometrical inter-instrument differences is based on the different degree of light permeation from the two geometries, which eventually results in a different degree of influence from near-surface bulk scattering. It was also shown that the d/0 instrument fulfils the assumptions of a diffuse field of reflected light from the medium only for samples that resemble the perfect diffuser but it yields an anisotropic field of reflected light when there is significant absorption or transmittance. In the latter case, the 45/0 proves to be less anisotropic than the d/0.In the process, the computational performance of the DORT2002 has been significantly improved. After the modification of the DORT2002 in order to include the 45/0 geometry, the Gauss-Newton optimization algorithm for the solution of the inverse problem was qualified as the most appropriate one, after testing different optimization methods for performance, stability and accuracy. Finally, a new homotopic initial-value algorithm for routine tasks (spectral calculations) was introduced, which resulted in a further three-fold speedup of the whole algorithm.
QC 20100707
PaperOpt, Paper Optics and Colour
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Barry, Laura Pass. "Optical Instruments Used with Prints in the Eighteenth Century." W&M ScholarWorks, 2004. https://scholarworks.wm.edu/etd/1539626436.
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Garner, Harry Douglas Jr. "Development of a grating interferometer for non-contact relative displacement measurement." Thesis, Georgia Institute of Technology, 1998. http://hdl.handle.net/1853/17086.
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Johnston, Steve Clarence. "An investigation into consequences of classifying orthogonal aberrations by degree." Diss., The University of Arizona, 1988. http://hdl.handle.net/10150/184377.
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The motivation for this research stems from the optical design problem. From a mathematical perspective the problem can be stated as follows: given a starting optical configuration and a set of variable parameters, determine the specific configuration which yields the global minimum of the merit function which represents the imaging quality of the system. Currently, no satisfactory solution to this problem has been found, although a process called "simulated annealing" has shown some potential. The idea behind this research is that perhaps a merit function can be constructed in such a way that information contained in higher order polychromatic aberration coefficients can be used to indicate the region of the global minimum. In pursuit of this, the construction of two physically significant merit functions (the wavefront variance and the mean square ray aberration) is formulated in such a way as to allow the segregation of aberration coefficients by order within the merit function. This suggests a sequence of merit "subfunctions" can be constructed in such a way that each member of the sequence is associated with a particular order of aberration, and that the sequence itself converges to the complete merit function. In order to compute the polychromatic aberration coefficients needed to construct the merit functions, an algorithmic approach to proximate ray tracing is developed. This is shown to be an extension of the original form of proximate ray tracing and has proved highly successful in the computation of polychromatic aberration coefficients. The behavior of three optical systems with respect to their effective design parameters is then investigated. The investigation takes the form of topographic maps of the merit subfunctions. A study of the maps reveals that the global topography of the subfunctions remains relatively invariant with respect to order. Also, any minima present tend to remain relatively stationary with respect to order, although any particular one can slowly migrate within some small region of parameter space.
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Yu, Xing Jie. "Optical components for LCOS projectors /." View abstract or full-text, 2004. http://library.ust.hk/cgi/db/thesis.pl?ELEC%202004%20YU.
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Biazon, Filho Alcino José. "Nova técnica de malha fechada para estabilização do ponto de operação de interrogadores de sensores com grade de bragg em fibras ópticas." [s.n.], 2012. http://repositorio.unicamp.br/jspui/handle/REPOSIP/260881.
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Orientador: José Antonio Siqueira DiasTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Elétrica e de Computação
Made available in DSpace on 2018-08-21T18:07:20Z (GMT). No. of bitstreams: 1 BiazonFilho_AlcinoJose_D.pdf: 3212736 bytes, checksum: 5eb7bde925a233493806c588f3c39cfe (MD5) Previous issue date: 2012
Resumo: Sensores de fibra óptica são imunes à interferência eletromagnética (EMI), e são uma excelente escolha para ser usado em ambientes eletricamente ruidosos aplicações em sensoriamento remoto, incluindo aeroespacial, ferroviário equipamentos de segurança militar e em linhas de alta tensão. Outras vantagens incluem o fato de que eles são compactos, leves e os sinais de medição podem ser transmitidos a distâncias muito grandes (da ordem de km). Os interrogadores convencionais para redes de Bragg (FBG) do sensor são equipamentos de custo elevado e não pode ser utilizado em aplicações de baixo custo. Neste trabalho é apresentada uma nova técnica de interrogação robusta e de baixo custo que apresenta uma boa precisão. A técnica, que utiliza um circuito de retroalimentação eletrônico para estabilizar o ponto de operação DC das grades de Bragg, permite a medição simultânea de ambos sinais AC e DC. Um protótipo do interrogador proposto foi projetado e implementado. A técnica exige apenas três componentes ópticos: um laser distribuído, um acoplador óptico e um fotodiodo. O interrogador foi testado com sucesso em uma aplicação de DC (medição de temperatura) e uma aplicação AC (medição de corrente elétrica). Os resultados experimentais mostraram que o controle eletrônico em malha fechada pode controlar o ponto de operação da FBG com uma precisão de ± 2 ppm
Abstract: Fiber optic sensors are immune to electromagnetic interference (EMI), and are an excellent choice for being used in electrically noisy environments sensing applications, including aerospace, rail, military security equipment and in high voltage power lines. Other advantages include the fact that they are compact, lightweight and the measured signals can be transmitted at very large distances (of the order of kilometers). The conventional interrogators for Fiber Bragg Gratings (FBG) sensor are high cost equipment and cannot be used in low cost applications. In this work it is presented a novel robust and low cost interrogation technique that presents good accuracy. The technique, which uses an electronic feedback loop to stabilize the DC operating point of the Bragg gratings, allows the simultaneous measurement of both AC and DC signals. A prototype of the proposed interrogator was designed and implemented. The technique requires only three optical components: a Distributed Feedback Laser, an optical coupler and one photodiode. The interrogator has been successfully tested in a DC application (temperature measurement) and an AC application (electrical current measurement). Experimental results showed that the electronic feedback loop can control the operation point of the FBG with a precision of ±2 ppm
Doutorado
Eletrônica, Microeletrônica e Optoeletrônica
Doutor em Engenharia Elétrica
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Ingraham, John. "Model automatic focusing system for linewidth measuring instruments /." Online version of thesis, 1985. http://hdl.handle.net/1850/11372.
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Wang, Gaoxuan. "Development of photonic instruments for measurement of aerosol optical properties." Thesis, Littoral, 2018. http://www.theses.fr/2018DUNK0470.
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À cause de leur diffusion et de leur absorption des radiations solaires, les aérosols atmosphériques jouent un rôle important dans l'évolution du climat terrestre. Les techniques de mesure actuelles apportent certes, des connaissances, sur le forçage radiatif mais les résultats possèdent généralement de larges incertitudes, souvent du même ordre de grandeur que la valeur elle-même. Ces incertitudes sont causées par le manque de précision sur les données liées aux propriétés optiques estimées de ces aérosols (comme l'absorption, la diffusion ou l'extinction). Elles découlent principalement des techniques de mesures actuelles : à l'effet de chargement des filtres (lors de mesures classiques par filtres), aux mesures limitées par l'étendue spectrale des instruments, aux conditions d'échantillonnage différents lors de mesures séparées, etc. Dans ce travail de thèse, j'ai développé puis testé des instruments optiques et électroniques dans le but d'augmenter la précision des mesures des coefficients d'extinction et d'absorption des aérosols. (1) Deux spectrophones PhotAccoustique (PA) sont développés afin d'améliorer les mesures d'absorption des aérosols grâce à des mesures directes et sans filtres. Une première génération utilisant un rayonnement à 444 nm permet de réduire les incertitudes de mesure de 20-30% (obtenue par la technique d'échantillonnage par filtres) à 7,4% et 4,6% pour la détermination des coefficients d'absorption massique du carbone suie et de cendres volcaniques, respectivement. Transformé en spectrophone PA à multi-longueurs d'onde opérant conjointement à 444,532 et 660 nm, il permet alors de caractériser la dépendance spectrale du Coefficient d'Absorption d'Ångström (CAA). Les valeurs du CAA du carbone suie sont en accord avec les résultats publiés. Celles obtenues lors de l'analyse de deux échantillons de cendres volcaniques résultant de l'éruption du Eyjafjallajökull sont similaires au CAA du carbone brun,prouvent la présence d'importantes quantités d'éléments organiques. (2) Un extinctiomètre, basé sur le principe de la spectroscopie d'absorption en cavité à source large bande et incohérente (IBBCEAS), est ensuite développé afin de suivre l'évolution des propriétés optiques d'Aérosols Organiques Secondaires (AOS) produits par la photolyse du 2-nitrophénol dans une chambre de simulation atmosphérique de l'University College de Cork (Irlande). Leurs coefficients d'extinction et d'absorption sont suivis par cet extinctiomètre et un spectrophone PA durant tout le processus de production. Les évolutions des propriétés optiques des AOS confirment l'effet du vieillissement atmosphérique. (3) Une nouvelle architecture de détection synchrone est développé afin de rendre notre prototype plus léger, plus compact, mieux adapté aux applications in situ et plus particulièrement aux drones, techniques émergentes qui permettent de caractériser le profil vertical des aérosols dans l'atmosphère. Cette détection synchrone innovante, évaluée lors de la mesure de la concentration de NO₂ ambiant (niveau de concentration de quelques ppbv) possède une précision et une reproductibilité de mesures comparable à la détection synchrone SR830, commercialisée par la société Stanford Research Inc. L'évaluation précise de l'impact climatique des aérosols nécessite une quantification exacte et non biaisée de leurs propriétés optiques. À ce jour, elle reste un défi majeur dans la recherche sur les sciences de l'atmosphère et du changement climatique. Ainsi, des informations sur la taille des particules (liée à l'absorption sélective en longueur d'onde) nécessitent des mesures étendues sur de larges régions spectrales du rayonnement solaire principale. Le développement d'un albédomète large bande à haute précision, dédié à la mesure simultanée des coefficients d'extinction et d'absorption des aérosols est en coursAtmospheric aerosols are known to play an important role in earth climate by scattering and absorbing solar radiation. However, the aerosol radiative forcing effect is still known with large uncertainties (almost equal to the magnitude of the aerosol radiative forcing). The uncertainties are mainly caused by inaccurate estimates of aerosol optical properties (such as its absorption, scattering and extinction coefficients) using the currently available measurement techniques, with result in filter loading effect in classic filter technique, the uncertainty due to different sampling conditions for separate measurements of aerosol optical properties in combination of different techniques or due to the measurements at limited spectral wavelength ranges. My PhD work was carried out on the developments and applications of optical and electronic instruments for accurate measurements of aerosol extinction and absorption coefficient : (1) Photoacoustic spectrophones were developed for filter-free direct measurements of aerosol absorption with high accuracy. Measurements uncertainties down to about 7.4% and 4.6% (compared to about 20-30% in filter-based measurements) were achieved for the determination of mass absorption coefficients of black carbon and volcanic ash samples, respectively, using a single-wavelength PA spectrophone operating at 444 nm. A 3-wavelength PA spectrophone operating at 444,532 and 660 nm was developed and deployed for characterizing wavelength-dependent optical properties of aerosol absorption Ångström coefficient (AAC). The determined AAC of black carbon was well consistent with the previously reported value. Our AAC values of two volcanic ash samples from 2010 eruptions of Eyjafjallajökull, similar to the AAC of brown carbon, indicated abundant organic compounds in the volcanic ash samples. The developed multi-wavelength PA spectrophone was tested and validated in an intensive field campaign measurements of environmental particles in Grenoble (France). Side-by-side inter-comparison measurements using an aethalometer showed a lineat correlation of the measured aerosol absorption coefficients from both instruments. (2) An extinctiometer based on IBBCEAS was developed for study of optical properties of secondary organic aerosol (SOA) produced from photolysis of 2-nitrophenol in an atmospheric simulation chamber at University College Cork (Ireland). Simultaneous monitoring of the SOA extinction and absorption (in conjuction with a PA spectrophone) coefficients was performed during its whole production process, the measured evolutions of the SOA optical properties highlighted the atmospheric aging effect. (3) In order to render optical sensor lightweight and suitable for field applications, in particular for the newly emerging unmanned aerial vehicle (UAV) applications, a novel architecture of lock-in amplifier (LIA) was proposed and developed in the framework of this Phd Research. The novel LIA, evaluated with an inter-comparison measurement of ambient NO₂ at the ppbv concentration level, shows an identical performance (in terms of measurements accuracy and precision) as the widely used commercial LIA (SR830, Stanford Research Inc.), while using a simplified and lightweight hardware architecture. Evaluation of the aerosol impact on climate requires accurate and unbiased quantification of the its wavelength-dependent optical properties over a wide spectral region of the major solar radiation, which can provide information on particle size (due to the wavelength dependence of scattering by fine particles) as well as insights on aerosol chemical composition (because of its wavelength selective absorption). To date, it is still a key challenge in atmospheric science and climate change research. Development of a broadband aerosol albedometer is ongoing, which is dedicated to simultaneous measurements of aerosol extinction and absorption coefficients with high-accuracy and high-precision
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McGee, P. K. "Optical studies in high-energy astrophysics /." Title page, contents and abstract only, 2001. http://web4.library.adelaide.edu.au/theses/09PH/09phm14485.pdf.
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Hui, Jeremy R. (Jeremy Ryan) 1977. "Optical tweezers using the Texas Instruments' Digital Micromirror Device(tm)." Thesis, Massachusetts Institute of Technology, 2001. http://hdl.handle.net/1721.1/86699.
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Thesis (M.Eng. and S.B.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2001.Includes bibliographical references.
by Jeremy R. Hui.
M.Eng.and S.B.
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Farrell, K. W. "Investigation of the accuracy of array radiometry for measuring pulsed radiation sources /." Online version of thesis, 1987. http://hdl.handle.net/1850/9665.
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WAN, DER-SHEN. "OPTICS FOR LARGE TELESCOPE." Diss., The University of Arizona, 1987. http://hdl.handle.net/10150/184226.
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There are two topics in this dissertation: one is to develop new phase reduction algorithms for test interferograms especially of large optics and the other one is to find more accurate analytical expression of surface deflection due to gravity when the mirror is supported in the axial direction. Two new algorithms for generating phase maps from interferograms are developed. Both methods are sensitive to small-scale as well as large-scale surface errors. The first method is designed to generate phase from an interferogram that is sampled and digitized only along fringe centers, as in the case of manual digitization. A new interpolation algorithm uses the digitized data more efficiently than the fitting of Zernike polynomials, so the new method can detect small-scale surface error better than Zernike polynomial fitting. The second algorithm developed here is an automatic phase reduction process which works on test interferograms recorded by CCD camera and transferred digitally to a personal computer through a frame grabber. The interferogram results from interference of the test wavefront with a tilted reference wave-front. Phase is generated by assuming it to be proportional to the intensity of the interferogram, apart from changes of sign and offset occurring every half fringe so as to make the phase increase monotoically. The error of the new algorithm is less than 1/20 waves in the wavefront, which can be reduced further by averaging several phase maps which are generated by interferograms with random phase shifts. The new algorithm is quick and involves no smoothing, so it can detect surface errors on large mirrors on a scale of several centimeters. A new model is developed to calculate analytically the surface deflection of a mirror supported axially on multiple points. It is based on thin plate theory, but considerations of thickness variation of a curved mirror, lightweight honeycomb structure and shear are included. These additions improve the accuracy of the calculated surface deflection, giving results close to those obtained from the accurate but computer intensive finite element model.
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He, Zaiqian. "Investigation of a multi-purpose optical measurement system /." View abstract or full-text, 2005. http://library.ust.hk/cgi/db/thesis.pl?IEEM%202005%20HE.
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Sasian, Alvarado Jose Manuel. "Imagery of the bilateral symmetrical optical system." Diss., The University of Arizona, 1988. http://hdl.handle.net/10150/184628.
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A brief study of the imagery of the bilateral symmetric optical system is presented. This study has been developed with a theoretical structure similar to that of the rotationally symmetric optical system and can be considered a generalization. It provides a simple, clear understanding of the main features of the imagery of the optical systems under consideration. and gives useful design insight. Some design examples are provided that illustrate the use and value of the theory developed.
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Thomas, Paul Dominic. "Characterisation of foams using vision systems." Thesis, University of Oxford, 1997. http://ora.ox.ac.uk/objects/uuid:f3822ed9-5af8-48e9-93fa-14d91cf8f9c3.
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The macroscopic behaviour of a two-phase foam depends on chemical properties such as surface tension, and physical properties such as the shape and size of the bubbles in the foam. The chemical properties of a foaming material may be deduced from experiments on the material in the single phase, for example surface tension or viscosity measurements. However, in order to measure structure the foam must clearly be present. This presents a difficult problem, especially for liquid foams which are often fast-moving and liable to collapse or rearrange on coming into contact with a probe. Optical techniques for examining foam structures can be non-invasive and take advantage of the semi-transparent nature of many liquid and solid foams. In particular, the application of confocal and axial tomography systems to real three-dimensional cellular foams can resolve their local geometric structure. This thesis covers the application of new optical tomographic techniques to the imaging of foams and presents the first three-dimensional models of bubble structure in liquid and solid foams. Complete descriptions of the hardware and software are included; imaging systems are based on a personal computer with an inexpensive video digitising card and a CCD camera. A clear advantage of optical systems is that the high data bandwidth required for tomography is available even on relatively slow computers by modern standards. Typically, all the data for a sixteen-million (256³) voxel model covering a world volume of 64mm³ can be acquired in a period of 30 seconds. Results from this work include the first three-dimensional solid models of observed foams, both aqueous and polyurethane-based, including volume models of minimal energy cellular foam configurations. In particular, Kelvin's proposed minimal cell and also bubbles from the Weaire-Phelan structure have been resolved by the system.
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Wong, Chiu Ho. "Color-filter LCOS microdisplay with space dithering algorithm for virtual resolution improvement /." View abstract or full-text, 2009. http://library.ust.hk/cgi/db/thesis.pl?ECED%202009%20WONGC.
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Wickholm, David Randall. "MERIT FUNCTION FOR BIOCULAR MAGNIFIERS." Thesis, The University of Arizona, 1985. http://hdl.handle.net/10150/275251.
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Rajendran, Rajarajan. "Model, design and demonstrate an integrated optical pulse distribution system /." free to MU campus, to others for purchase, 2004. http://wwwlib.umi.com/cr/mo/fullcit?p1426095.
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Allan, James Donald Campbell. "An application of optical interference to dynamic position measurement in three dimensions." Thesis, University of Edinburgh, 1988. http://hdl.handle.net/1842/6627.
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This thesis is concerned with the measurement of the positions of points and bodies moving in trajectories in three dimensions, and the use of a new technique of optical interference which allows such measurements to be made dynamically. A variety of existing techniques for both static and dynamic three-dimensional position measurement are discussed, and the design of the new interferometer is introduced. The geometry of points, curves and surfaces in three dimensions is examined, with emphasis on the intersection of the point loci represented by the coordinate output of measuring instruments. The coordinates output by the interferometer represent surface loci which are quadric surfaces. A method of calculating the position and orientation of a body using three quadric surface intersection curves is presented. Diffraction of monochromatic light at an aperture is considered and it is shown that an interferometer working by division of wavefront can be used to obtain continuous information about the movement of the source of radiation, with that source free to move in up to three dimensions. A lens may be used to produce a compact instrument based on these principles. The diffraction integral equations are modified to incorporate the effect of a lens in the diffraction field. It is shown that even complex lenses can be represented by a few parameters in the diffraction equations. From the evaluation of these diffraction integrals, it is shown how the movement of interference fringes provides a coordinate output and how this is related to the locus of the radiation source. A method of obtaining very high resolution measurements of interference fringe pattern movement is presented. The interferometer was built and tested and the above theory verified in practice in a series of optical bench tests. The implementation of a system which uses this interferometer to measure the dynamic performance of industrial robots is considered. The optimum positions for the instruments are derived, and the method of designing the interferometer to give the required resolution is presented.
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Cho, Myung Kyu. "Structural deflections and optical performances of lightweight mirrors." Diss., The University of Arizona, 1989. http://hdl.handle.net/10150/184875.
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A parametric design study of light weight mirror shapes with various support conditions was performed utilizing the finite element program NASTRAN. Improvements in the mirror performance were made based on the following design criteria: (1) minimization of the optical surface wavefront variations, (2) minimization of the self-weight directly related to cost of manufacturing, and (3) optimal location of support points. A pre-processor to automatically generate a finite element model for each mirror geometry was developed in order to obtain the structural deformations systematically. Additionally, a post-processor, which prepares an input data file for FRINGE (an optical computer code) was developed for generating the optical deflections that lead to the surface wavefront variations. Procedures and modeling techniques to achieve the optimum (the lightest and stiffest mirror shape due to self-weight) were addressed. Fundamental natural frequency analyses, for contoured back mirror shapes for a variety of support conditions, were performed and followed by comparisons of the results which were obtained from NASTRAN and a closed-form approximate solution. In addition, element validity and sensitivity studies were conducted to demonstrate the behavior of the element types provided in the NASTRAN program when used for optical applications. Scaling Laws for the evaluations of the optical performances and the fundamental frequencies were established.
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Wizinowich, Peter Lindsay. "New technologies for polishing and testing large optics." Diss., The University of Arizona, 1989. http://hdl.handle.net/10150/184849.
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Two new technologies, for polishing and testing large optics, are presented in this dissertation. The first is a new approach to generating and polishing aspheric surfaces which utilizes a full size stressed lap. The lap specifications are chosen to automatically generate a specific amount of spherical aberration. The required comatic distortion of the lap is induced by a system of levers and springs which are stretched and relaxed as the lap moves. A lap was constructed to grind and polish a 20cm glass blank. The resultant polished surface, in agreement with the predicted asphericity, has 28 microns of spherical aberration at its edge, appropriate for a F/2.0 convex paraboloid. The average radial profile has a residual peak-to-valley error of 200nm and an rms error of 60nm. This experiment serves as a first successful test of the stressed lap concept and as a demonstration of a new method for generating aspheric secondary mirrors. The second new technology is concerned with testing large optics where vibrations can be a serious problem. A modification to the usual phase shifting interferometry reduction algorithm permits measurements to be taken fast enough to essentially freeze out vibrations. Only two interferograms are needed with an exact phase relationship; and these can be recorded very rapidly on either side of the interline transfer of a standard CCD video camera, prior to charge transfer readout. The third required interferogram is a null. An analysis of potential phase errors was performed for this "2 + 1" algorithm. In the developed implementation, two frequencies, dν/ν≈10⁻⁸, are generated with orthogonal polarizations. A Pockels cell rapidly switches the frequency entering the interferometer, resulting in a phase shift over the long path difference of the interferometer. The two time critical interferograms are acquired with a 1ms separation resulting in a reduction in sensitivity to vibration of one to two orders of magnitude. Laboratory tests were performed to compare this "2 + 1" system with a commercial phase shifting package. Similar phase determination accuracies were found when vibrations were low. However, the "2 + 1" system also succeeded when vibrations were large enough to wash out video rate fringes.
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Even-Sturlesi, Doron. "A systematic approach to global optical design." Diss., Georgia Institute of Technology, 1990. http://hdl.handle.net/1853/29834.
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Aubuchon, Matthew Stephen. "Study of an optical power splitter with high power capacity using prism coupling and tapered waveguides /." free to MU campus, to others for purchase, 2004. http://wwwlib.umi.com/cr/mo/fullcit?p1421109.
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Baldwin, Dan, Andrew Szentgyorgyi, Stuart Barnes, Jacob Bean, Sagi Ben-Ami, Patricia Brennan, Jamie Budynkiewicz, et al. "Advanced structural design for precision radial velocity instruments." SPIE-INT SOC OPTICAL ENGINEERING, 2016. http://hdl.handle.net/10150/622418.
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The GMT-Consortium Large Earth Finder (G-CLEF) is an echelle spectrograph with precision radial velocity (PRV) capability that will be a first light instrument for the Giant Magellan Telescope (GMT). G-CLEF has a PRV precision goal of 40 cm/sec (10 cm/s for multiple measurements) to enable detection of Earth-like exoplanets in the habitable zones of sun-like stars'. This precision is a primary driver of G-CLEF's structural design. Extreme stability is necessary to minimize image motions at the CCD detectors. Minute changes in temperature, pressure, and acceleration environments cause structural deformations, inducing image motions which degrade PRV precision. The instrument's structural design will ensure that the PRV goal is achieved under the environments G-CLEF will be subjected to as installed on the GMT azimuth platform, including: Millikelvin (0.001 K) thermal soaks and gradients 10 millibar changes in ambient pressure Changes in acceleration due to instrument tip/tilt and telescope slewing Carbon fiber/cyanate composite was selected for the optical bench structure in order to meet performance goals. Low coefficient of thermal expansion (C 1E) and high stiffness-to-weight are key features of the composite optical bench design. Manufacturability and serviceability of the instrument are also drivers of the design. In this paper, we discuss analyses leading to technical choices made to minimize G-CLEF's sensitivity to changing environments. Finite element analysis (FEA) and image motion sensitivity studies were conducted to determine PRV performance under operational environments. We discuss the design of the optical bench structure to optimize stiffness to -weight and minimize deformations due to inertial and pressure effects. We also discuss quasi-kinematic mounting of optical elements and assemblies, and optimization of these to ensure minimal image motion under thermal, pressure, and inertial loads expected during PRV observations.
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Montarou, Carole Claudette. "Low-level birefringence methods applied to the characterization of optical fibers and interconnects." Available online, Georgia Institute of Technology, 2005, 2005. http://etd.gatech.edu/theses/available/etd-04072005-112316/unrestricted/montarou%5Fcarole%5Fc%5F200505%5Fphd.pdf.
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Thesis (Ph. D.)--Electrical and Computer Engineering, Georgia Institute of Technology, 2005.Phillip First, Committee Member ; Gee-Kung Chang, Committee Member ; John Buck, Committee Member ; Glenn Smith, Committee Member ; Thomas Gaylord, Committee Chair. Includes bibliographical references.
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De, Vries Marten J. "Simultaneous measurement of strain and temperature using liquid core optical fiber sensors." Thesis, This resource online, 1993. http://scholar.lib.vt.edu/theses/available/etd-03042009-040438/.
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Glen, Andrew. "A new optical particle counter for in situ measurements of stratospheric aerosol size distributions." Laramie, Wyo. : University of Wyoming, 2007. http://proquest.umi.com/pqdweb?did=1400968731&sid=1&Fmt=2&clientId=18949&RQT=309&VName=PQD.
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Poe, Blake. "Design and performances of a stabilized pointable stratospheric balloon system." abstract and full text PDF (UNR users only), 2008. http://0-gateway.proquest.com.innopac.library.unr.edu/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:1460772.
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Sarfaraz, Mohamad Ali 1960. "Reconstruction of electrodes and pole pieces from randomly generated axial potential distributions of electron and ion optical systems." Thesis, The University of Arizona, 1988. http://hdl.handle.net/10150/276783.
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The purpose of this investigation is to examine synthesis for reconstruction of electrostatic lenses having an axial potential distribution four times continuously differentiable. The solution of the electrode and pole piece reconstruction is given. Spline functions are used to approximate a continuous function to fit a curve. The present method of synthesis is based on cubic spline functions, which have only two simultaneous continuous derivatives, and all the other higher derivatives are ignored. The fifth-order or quintic spline is introduced simply because it has four simultaneous continuous derivatives. So the reconstruction program would have three terms appearing in the series expansion of the off-axis potential distribution, with regard to two terms when using cubic functions.
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Bushroe, Frederick Nicholas 1964. "An optical head for a magneto-optic disk test system." Thesis, The University of Arizona, 1989. http://hdl.handle.net/10150/277154.
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Design and operation of modular optical head for a magneto-optic test system are described. Alternate solutions to design problems are discussed. A 30mW semiconductor laser with an integrated 250MHz oscillator is selected. The oscillator is used to modulate laser read current for a reduction in laser feedback noise. A collimating lens with an appropriate focal length is chosen so the beam's truncation at the objective yields the maximum write power density. Astigmatism associated with the laser diode is reduced to 0.125 waves by defocusing the collimating lens and circularizing with an anamorphic prism pair. Head components are aligned within several minutes of arc by using alignment apertures and an autocollimator. Aberrations due to tilt between the disk and beam are examined and coma is found to be the major contributor.
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Karbaschi, Arash. "Dynamic pattern recognition and data storage using localized holographic recording." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/24753.
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Thesis (Ph.D.)--Electrical and Computer Engineering, Georgia Institute of Technology, 2008.Committee Chair: Adibi, Ali; Committee Member: Altunbasak, Yucel; Committee Member: Callen Jr, William R; Committee Member: Gaylord, Thomas K; Committee Member: McLaughlin, Steven W; Committee Member: Trebino, Rick.
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Liu, Ying-Moh Edward. "Use of annular subapertures with focus control for testing rotationally symmetric optical systems." Diss., The University of Arizona, 1987. http://hdl.handle.net/10150/184300.
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A subaperture configuration to test aspheric optical components or systems is developed. The method developed has potential for testing rotationally symmetric aspheres without the use of null lenses. The aperture is divided into annular subaperture regions and an interferometer is refocused for each region to reduce the fringe density. Essential mathematical treatments involving annular subapertures, such as annular Zernike polynomials, are provided in detail. Numerical and experimental validations of the algorithm are described. Tolerance analyses on subaperture measurements are given. Computer programs were written to link the subaperture Zernike coefficients and to determine the full-aperture Zernike coefficients.
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Dante, Alex 1979. "Uma nova técnica para caracterização de grades de Bragg em fibra óptica utilizando um método de deconvolução." [s.n.], 2012. http://repositorio.unicamp.br/jspui/handle/REPOSIP/261376.
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Orientador: Elnatan Chagas FerreiraDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Elétrica e de Computação
Made available in DSpace on 2018-08-20T12:19:42Z (GMT). No. of bitstreams: 1 Dante_Alex_M.pdf: 3529877 bytes, checksum: 4dd1be9e526e3698ffe5df07e12d5b62 (MD5) Previous issue date: 2012
Resumo: Sensores a fibra óptica utilizando grades de Bragg em fibra (fiber Bragg grating - FBG) estão se tornando cada dia mais importantes, dada a quantidade de aplicações nas quais vêm sendo empregados. Algumas das principais características dos sensores a FBG são: imunidade à interferência eletromagnética (EMI), isolamento elétrico, baixo peso, flexibilidade, e transmissão de informações a longa distância. Eles estão sendo empregados na medida de temperatura, deformação, carga, tensão mecânica e vibração. Estão presentes também em estruturas inteligentes, onde sensores a FBG distribuídos são incorporados à estrutura, permitindo a monitoração em tempo real das condições estruturais de pontes, trilhos ferroviários e aviões. Este trabalho apresenta uma nova técnica de caracterização de FBGs utilizando deconvolução. Nesta técnica, utiliza-se uma FBG sintonizável, cujo perfil de reflexão é bem conhecido, para caracterização de outra FBG, cujo perfil é inicialmente desconhecido. Utilizando placas eletrônicas com componentes de baixo custo, e um software desenvolvido em LabVIEW®, no qual implementamos a deconvolução dos perfis das FBGs, essa técnica permite o levantamento do perfil de reflexão e outros parâmetros, como a largura espectral FWHM (do inglês Full Width at Half Maximum) e o comprimento de onda de Bragg 'lâmbda'B, de uma FBG. Os resultados obtidos tornaram possível a validação da técnica proposta e permitem concluir que ela é robusta e, com refinamentos matemáticos que podem ser implementados no processo de deconvolução, permite a construção de um caracterizador de FBGs preciso e de custo bem inferior a equipamentos disponíveis comercialmente
Abstract: Optical fiber sensors using fiber Bragg gratings (FBG) are becoming increasingly important, given the amount of applications in which they are being used. Some of the most important characteristics of FBGs are: electromagnetic interference (EMI) immunity, light weight, flexibility, and long range information transmission. FBG sensors are being used in the measurement of temperature, deformation, load, strain and vibration. They are also being used in smart structures, where several distributed sensing FBGs are embedded in materials to allow for the real-time monitoring of the structural conditions of bridges, railroad tracks and airplanes. A new technique for the FBGs characterization using deconvolution is presented. In this technique, a tunable FBG, whose reflection spectrum is known, is used to discover another FBGs profile, which is previously unknown. Using low-cost electronic parts and software developed in LabVIEW, which performs the deconvolution of both FBGs spectra, this technique allows the measurement of the FBG reflection spectrum, its FWHM (Full Width at Half Maximum), and the Bragg center wavelength 'lambda'B. The obtained results enables to validate the proposed technique, allowing concluding that it is robust and, if numerical refinement is implemented, it will be possible to build a low-cost FBG characterization device, in comparison with other commercial devices used for this purpose
Mestrado
Eletrônica, Microeletrônica e Optoeletrônica
Mestre em Engenharia Elétrica
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Ameli, Reza. "An optogenetic headstage for optical stimulation and neural recording in life science applications." Master's thesis, Université Laval, 2015. http://hdl.handle.net/20.500.11794/26055.
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L'optogénétique est une nouvelle méthode de contrôle de l’activité neuronale dans laquelle la lumière est employée pour activer ou arrêter certains neurones. Dans le cadre de ce travail, un dispositif permettant l’acquisition de signaux neuronaux et conduisant à une stimulation optogénétique de façon multicanale et temps-réel a été conçu. Cet outil est muni de deux canaux de stimulation optogénétique et de deux canaux de lecture des signaux neuronaux. La source de lumière est une DEL qui peut consommer jusqu’à 150 milliampères. Les signaux neuronaux acquis sont transmis à un ordinateur par une radio. Les dimensions sont d’environ 20×20×15 mm3 et le poids est de moins de 7 grammes, rendant l’appareil utile pour les expériences sur les petits animaux libres. Selon nos connaissances actuelles, le résultat de ce projet constitue le premier appareil de recherche optogénétique sans-fil, compact offrant la capture de signaux cérébraux et la stimulation optique simultanée.Optogenetics is a new method for controlling the neural activity where light is used to activate or silence, with high spatial and temporal resolution, genetically light-sensitized neurons. In optogenetics, a light source such as a LED, targets light-sensitized neurons. In this work, a light-weight wireless animal optogenetic headstage has been designed that allows multi-channel simultaneous real-time optical stimulation and neural recording. This system has two optogenetic stimulation channels and two electrophysiological reading channels. The optogenetic stimulation channels benefit from high-power LEDs (sinking 150 milliamps) with flexible stimulation patterns and the recorded neural data is wirelessly sent to a computer. The dimensions of the headstage are almost 20×20×15 mm3 and it weighs less than 7 grams. This headstage is suitable for tests on small freely-moving rodents. To the best of our knowledge, this is the first reported fully wireless headstage to offer simultaneous multichannel optical stimulation along with multichannel neural recording capability.
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Clemente, Pesudo Pere Xavier. "Sistemes formadors d’imatges multidimensionals amb detecció integrada." Doctoral thesis, Universitat Jaume I, 2015. http://hdl.handle.net/10803/669001.
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L`objectiu general de la tesi és el desenvolupament i anàlisi de sistemes formadors d`imatges multidimensionals amb detecció integrada. Les càmeres multidimensionals no sols enregistren la distribució espacial de la irradiància de la llum, com les càmeres convencionals, sino també d`altres paràmetres físics de la radiació com l`espectre, la polarització o la fase. L`ús d`aquestes càmeres no convencionals s`ha estès a diferents àmbits com la medicina, teledetecció, agricultura, biologia,... ja que aporten informació valuosa que no s`aconsegueix amb una càmera convencional. Mentre les càmeres multidimensionals estàndard utilitzen en general sensors bidimensionals, en aquesta tesi es proposen càmeres multidimensionals amb detecció integrada. Basats en la càmera d`un sol píxel, aquests sistemes utilitzen moduladors espacials de radiació per a aplicar tècniques d`il.luminació estructurada i realitzar el mostreig de l`objecte sense parts mòbils. Les càmeres d`un sol píxel presenten principalment tres avantatges. Poden treballar fàcilment en regions exòtiques de l`espectre, com IR, Raigs X, UV o THz. Són adients per a ambients de baixa il.luminació. I, finalment, són útils per a tècniques on sols es poden mesurar irradiàncies integrades com per exemple microscòpia Raman o confocal de fluorescència. Amés s`ha utilitzat la tècnica de compressive sensing per optimitzar el procés de multiplexat i la tècnica ghost imaging com una forma de multiplexar. Particularment, es presenten una càmera híper-espectral, una polarimètrica, una híper-espectral polarimètrica i dues hologràfiques. En resum, s`han dissenyat càmeres multidimensionals d`un sol píxel amb les prestacions de les càmeres multidimensionals estàndard i els avantatges de la càmera d`un sol píxel.El objetivo general de la tesis es el desarrollo y análisis de sistemas formadores de imágenes multidimensionales con detección integrada. Les cámaras multidimensionales no sólo registran la distribución espacial de la irradiancia de la luz, como las cámaras convencionales, sino también de otros parámetros físicos de la radiación como el espectro, la polarización o la fase. El uso de estas cámaras no convencionales se ha extendido a diferentes ámbitos como la medicina, teledetección, agricultura, biología,... ya que aportan información valiosa que no se consigue con una cámara convencional. Mientras las cámaras multidimensionales estándar utilizan en general sensores bidimensionales, en esta tesis se proponen cámaras multidimensionales con detección integrada. Basados en la cámara de un sólo píxel, estos sistemas utilizan moduladores espaciales de radiación para aplicar técnicas de iluminación estructurada y realizar el muestreo del objeto sin partes móviles. Las cámaras de un sólo píxel presentan principalmente tres ventajas. Pueden trabajar fácilmente en regiones exóticas del espectro, como IR, Rayos X, UV o THz. Son adecuadas para ambientes de baja iluminación. Y, finalmente, son útiles para técnicas donde sólo se pueden medir irradiancias integradas tales como la microscopia Raman o confocal de fluorescencia. Además se ha utilizado la técnica de compressive sensing para optimizar el proceso de multiplexado y la técnica ghost imaging como una forma de multiplexado. Particularmente, se presentan una cámara híper-espectral, una polarimétrica, una híper-espectral polarimétrica y dos holográficas. En resumen, se han diseñado cámaras multidimensionales de un sólo píxel con las prestaciones de las cámaras multidimensionales estándar y las ventajas de la cámara de un sólo píxel.
The main goal of the thesis is the development and analysis of multidimensional imaging systems with a bucket detector. Multidimensional cameras not only record the spatial distribution of the light irradiance but also of other physical parameters of the light radiation such as the spectrum, polarization or phase. The application of these non-conventional cameras has spread out in different areas such as medicine, remote sensing, agriculture, or biology, due to the valuable information that they provide in contrast with conventional cameras. While, in general, standard multidimensional cameras use sensors arrays, the multidimensional cameras proposed in this thesis use only a bucket detector. They are based in the concept of single-pixel camera, which employ spatial light modulators to apply structured illumination techniques, sampling the object without any moving parts. Single-pixel cameras exhibit principally three advantages. They can work at exotic regions of spectrum such as IR, X ray, UV, or THz. They are suitable for low-level illumination scenarios. And, finally, they can be useful in imaging methods based on scaning techniques, such as Raman or confocal fluorescence microscopy. Moreover, compressive sensing technique is employed to optimize multiplexing process and a ghost imaging technique is applied as a way of multiplexing. Particularly, a hyper-spectral, a polarimetric, a hyper-spectral polarimetric and two holographic cameras are shown in this thesis. In conclusion, multidimensional single-pixel cameras are designed with the benefits of multidimensional standard cameras and the advantages of a single-pixel camera.
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Kenyon, Suzanne Laura Physics Faculty of Science UNSW. "A universe of sky and snow: site-testing for optical astronomy at Dome C, Antarctica." Awarded by:University of New South Wales. Physics, 2007. http://handle.unsw.edu.au/1959.4/40822.
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The unique advantages for astronomy on the Antarctic plateau are now well established. In particular, Dome C, Antarctica is potentially one of the best new sites for optical, infrared and sub-millimeter astronomy, presenting the opportunity to build unique astronomical instruments. Located high on the Antarctic plateau, Dome C offers low wind, clear skies, and negligible precipitation. This thesis addresses three additional properties of the site relevant to optical astronomy-sky brightness, atmospheric extinction and optical turbulence. The sky at an optical astronomy site must be dark, and the atmosphere very clean with minimal light extinction. At present little is known from an astronomer's perspective about the optical sky brightness and atmospheric extinction at most Antarctic sites. The high latitude of Dome C means that the Sun spends a relatively small amount of time far below the horizon, implying longer periods of astronomical twilight and less optical dark time than other sites, especially those close to the equator. We review the contributions to sky brightness at high-latitude sites, and calculate the amount of usable dark time at Dome C. We also explore the implications of the limited sky coverage of high-latitude sites, and review optical extinction data from the South Pole. A proposal to extend the amount of usable dark time through the use of polarising filters is examined, and we present the design and calibration of an instrument (called Nigel) to measure the brightness, spectrum and temporal characteristics of the twilight and night sky. The atmospheric turbulence profile above an astronomical site limits the achievable resolution and sensitivity of a telescope. The atmospheric conditions above high plateau Antarctic sites are different to temperate sites; the boundary layer of turbulence is confined very close to the surface, and the upper atmosphere turbulence very weak. We present the first winter-time turbulence profiles of the atmosphere above Dome C, and characterise the site in terms of the achievable precision for photometry and astrometry, and the isoplanatic angle and coherence time for the adaptive optics.
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Rezaei, Alireza. "Detection of alterations in historical violins with optical monitoring." Electronic Thesis or Diss., université Paris-Saclay, 2022. http://www.theses.fr/2022UPASG054.
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La conservation préventive est le contrôle continu de l'état d'une œuvre d'art pour réduire le risque de dommages et minimiser les restaurations. De nombreuses méthodes ont été proposées pour atteindre cet objectif, soit à partir de données unimodales, soit par combinaison de différentes techniques d'analyse. Dans ce travail, nous présentons deux algorithmes probabilistes de clustering pour la détection d'altérations sur des surfaces vernies, telles que celles des instruments de musique historiques. Les deux méthodes reposent sur une approche a-contrario et le critère Nombre de Fausses Alarmes (NFA). La première méthode aborde le problème de la détection de changement entre une paire d'images couleur en analysant leur image de différence. Il considère simultanément l'information spectrale et spatiale avec un seul modèle de bruit. La deuxième méthode travaille avec une séquence d'images et analyse l'évolution des zones altérées entre les images. Les deux méthodes sont robustes au bruit et évitent réglage des paramètres ainsi que toute hypothèse sur la forme et la taille de la modification domaines. Dans les deux cas, des tests ont été effectués sur des séquences d'images UVIFL (images de fluorescence induite par les UV) incluses dans le jeu de données "Violins UVIFL imagery". UVIFL est une technique de diagnostic bien connue, utilisée pour voir les détails d'une surface qui ne sont pas perceptibles à la lumière visible. Les résultats obtenus prouvent la capacité de l'algorithme pour détecter correctement les régions altérées. Des comparaisons avec d'autres les méthodes de clustering de pointe montrent une amélioration à la fois de la Precision et du RecallPreventive conservation is the constant monitoring of the state of conservation of an artwork to reduce the risk of damage in order to minimise the necessity of restorations. Many methods have been proposed to achieve this goal, generally including a mix of different analytical techniques. In this work, we present two probabilistic clustering algorithms for the detection of alterations on varnished surfaces, in particular those of historical musical instruments. Both methods are based on the a-contrario framework and the Number of False Alarms (NFA) criterion. The first one tackles the problem of detecting changes between a pair of colour images by analysing their difference map. It considers simultaneously grey-level and spatial density information with a single background model. The second method works with a sequence of images and analyses the evolution of the changed areas between frames. Both methods are robust to noise and avoid parameter tuning as well as any assumption about the shape and size of the changed areas. In both cases, tests have been conducted on UV-induced fluorescence (UVIFL) image sequences included in the “Violins UVIFL imagery” dataset. UVIFL photography is a well-known diagnostic technique used to see details of a surface not perceivable with visible light. The obtained results prove the capability of the algorithm to properly detect the altered regions. Comparisons with other state-of-the-art clustering methods show improvement in both precision and recall
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Cruz, Renato Antonio. "Confecção de lentes acrílicas para o ensino de ótica." Universidade de São Paulo, 1997. http://www.teses.usp.br/teses/disponiveis/76/76132/tde-19092007-105831/.
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A grande carência de material experimental adequado para o ensino de Ótica no Brasil motivou o desenvolvimento de um processo de moldagem de lentes acrílicas, pelo Centro de Divulgação Científica e Cultural. Aproveitando tecnologia já existente na Universidade, o CDCC desenvolveu um processo de moldagem por compressão, relativamente barato, utilizando a placa acrílica comercial como material moldável. O presente trabalho consiste em caracterizar e avaliar esse processo de moldagem de lentes acrílicas. Para tanto, são levantadas as principais características físicas do material moldável. A qualidade ótica da lente moldada é analisada com base em alguns ensaios, tais como medidas de aberrações geométricas e de birrefringência induzida. Os resultados obtidos permitem a determinação dos parâmetros ideais do processo, e demonstram a possibilidade de obtenção de lentes acrílicas de excelente qualidade ótica para o ensino básico, a um custo acessível.The necessity of experimental optical materials in Brasil for basic learning was the principal motivation for the development of the process to produce acrylic lens in the Centro de Divulgação Científico e Cultural (CDCC). All the process developed use low cost commercial acrylic and a moulding procedure to produce the lens. In this work we characterize the moulding process and the physical properties for the material. The optical quality for the moulding lens was determine measuring: aberrations and the induce birefringence. These results allow us to determine the optimal parameters for the process, and the possibility to production of high quality lens for the basic schools.
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Leung, Kit Yee. "Single-panel sequential-color LCOS projectors using LED lamps /." View abstract or full-text, 2008. http://library.ust.hk/cgi/db/thesis.pl?ECED%202008%20LEUNG.
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Pierce, Mary E. "Engineering a fiber-optic implantable cardiovascular biosensor /." free to MU campus, to others for purchase, 2004. http://wwwlib.umi.com/cr/mo/fullcit?p1422954.
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Montarou, Carole C. "Low-level birefringence methods applied to the characterization of optical fibers and interconnects." Diss., Georgia Institute of Technology, 2005. http://hdl.handle.net/1853/6993.
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Birefringence measurements are of great importance in a plethora of applications spanning from biology to optical communications. Birefringence measurements of nerve-fiber layers have emerged as an important diagnostic technique for early detection of glaucoma. Stress-induced birefringence in optical devices affects their performances by causing Polarization-Mode Dispersion (PMD) and Polarization-Dependent Loss (PDL). Stress-relaxation constitutes a key phenomenon governing the fabrication of some optical devices such as Long-Period Fiber Gratings (LPFGs). This drives the need to develop accurate optical instrumentation techniques to evaluate form and stress-induced birefringence.
This thesis deals with the development of new high-accuracy techniques for the characterization of stress-induced birefringence in optical devices. The new Two-Waveplate Compensator (TWC) technique is presented for single-point retardation measurements. It is extensively compared theoretically and experimentally to existing techniques including the Snarmont and Brace-Khler techniques. The Phase-Stepping Two-Waveplate Retarder (PSTWR) is also presented for high-accuracy measurements of retardation magnitude and orientation. The Colorimetry-Based Retardation Method (CBRM) is presented to measure retardation using white-light interference colors. The technique is implemented using a polarization microscope and a spectrophotometer.
The TWC and the Brace-Khler methods are implemented for full-field retardation measurements using a polarization microscope. Their accuracies are quantified over the entire field-of-view for small retardations. They are applied to the stress-induced birefringence imaging of LPFGs and polymer pillar waveguides. The TWC technique achieves an accuracy of 0.06 nm and a sensitivity of 0.07 nm. The Brace- Khler technique achieves an accuracy of 0.04 nm and a sensitivity of 0.09 nm. The spatial resolution of both techniques is 0.45 and #61549;m.
A Fourier-based algorithm is presented to compute the inverse Abel transform relating the retardation to the axial residual stress profile in optical fibers. It is used to calculate the residual stress profiles of single-mode fibers from full-field retardation measurements with the TWC and Brace- Khler techniques. The stress profiles computed in this work are in very good agreement with previously reported results in the literature. The TWC technique produces the most accurate stress measurements. The TWC technique is used to investigate the stress-relaxation phenomena in LPFGs fabricated using CO2 laser irradiations.
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Harmer, Stuart William. "Enhanced absorptance photocathodes." Thesis, University of Sussex, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.311348.
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This thesis addresses one of the major limiting factors in the performance of photomultipliers, that is that the photocathodes employed often only absorb a small fraction, typically less than 25%, of the power in the incident light. Current photocathodes are almost exclusively planar and the starting point of the thesis is the mathematical modelling of both, semitransparent and reflective planar photocathodes. The analysis shows that the absorptance of semitransparent photocathodes increases for light incident beyond the critical angle needed for Attenuated Total Internal Reflection (ATIR). Reflective type planar photocathodes could certainly have their absorptance enhanced by use of silver rather than nickel substrates, as increases in absorptance of 2-3 times are possible for red light. The proposed method for remedying the inherent loss in sensitivity of photomultipliers caused by the non-total absorption of light in the photocathode was to employ a ridged substrate in the photocathode. The ridged substrate, glass or metal for semitransparent and reflective type photocathodes respectively, allows the light multiple interactions with the photoemissive layer. In the case of semitransparent photocathodes ATIR would mean no power is transmitted for those interactions that take place beyond the critical angle of incidence. The mathematical modelling and subsequent analysis of ridged photocathodes show enhanced absorptance (20-30 fold improvements are certainly achievable), especially for light in the red end of the operating spectral range. Further gains in quantum efficiency can follow by the reduction of the optimum photocathode thickness, resulting from the structure, while maintaining high absorptance. Some subwavelength structures are also modelled and analysed to ascertain whether this route could be used to improve the absorptance of photocathodes, the results are inconclusive but generally indicate anti-reflective, rather than absorbing properties. Finally the extremely sparse nature of published permitivity data has been rectified by our own measurements for the permitivities of certain photocathodes over a wide wavelength range.
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O'Brien, Anthony. "Development and Deployment of Optical Instruments to Measure Trace Atmospheric Species: I. Water Isotopologues; II. Glyoxal; III. Iodine Monoxide." Thesis, Harvard University, 2012. http://dissertations.umi.com/gsas.harvard:10075.
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Understanding future climate requires observations of trace species that can significantly influence the chemical or radiative properties of the atmosphere. The development of optical instruments, utilizing laser-systems as high-resolution light sources, for making in situ observations of trace species from either airborne- or ground-based platforms and results from field campaigns are presented. Glyoxal, the smallest \(\alpha\)-dicarbonyl, is a common product during the oxidation of volatile organic compounds. An instrument using the technique of laser-induced phosphorescence was developed to measure glyoxal at the part per trillion by volume (pptv) level from a tower in a forest canopy. The instrument was deployed as part of the Community Atmosphere-Biosphere INteractions EXperiment. The instrumental limit of detection is 3 pptv with a 1-minute acquisition time. Nearly continuous measurements of glyoxal ranging between 5 – 75 pptv were acquired throughout the campaign and vertical gradients in the forest canopy were found to be driven by elevated temperature. A sensitive instrument using laser-induced fluorescence detection was developed and deployed into remote marine environments to measure iodine monoxide (IO) where the mixing ratio is on the order of 1 – 5 pptv. The challenges and solutions of operating in this environment and results from the field and laboratory are discussed. Laboratory experiments show that IO can be generated from Laminaria digitata, a subtidal kelp species, in the presence of ozone. Observations of the isotopic composition of condensed and vapor water above a large summertime tropical convective system obtained by Hoxotope and ICOS instruments during the TC4 campaign are used to analyze the role of convection in the lower tropical transition layer (TTL). Regions of ice that are characteristic of either convective lofting or in situ condensation are encountered above an active deep tropical convective system. Ice is an important component of water transport models in the TTL, yet its isotopic composition is a relatively unconstrained parameter. The implications from the direct observations of the isotopic composition of ice during convection is explored with respect to transport models of water in the TTL.Chemistry and Chemical Biology
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Moraes, Filho Alexandre Francisco de. "Desenvolvimento de transdutores baseados em paládio-porfirinas para a detecção de O2 através dos tempos de vida de fosforescência." Universidade Tecnológica Federal do Paraná, 2013. http://repositorio.utfpr.edu.br/jspui/handle/1/512.
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Este trabalho apresenta o desenvolvimento de membranas sensoras para a detecção de oxigênio gasoso através da fosforescência resolvida no tempo, além de descrever um sistema de medição para avaliação de desempenho destes elementos. Os transdutores são formados a partir da imobilização em matrizes poliméricas, de poli(cloreto de vinila) e poliestireno, das seguintes metaloporfirinas de paládio: Coproporfirina I, Mesoporfirina IX, Deuteroporfirina IX e meso-Tetrapenta(fluorofenil)porfirina. O feixe de excitação das membranas é proveniente de um LED violeta, sendo que a fosforescência emitida pelos luminóforos é detectada por uma miniválvula fotomultiplicadora. Relatam-se a produção das membranas sensoras e seus principais parâmetros, como curvas de calibração, envelhecimento, tempos de resposta e fotoestabilidade. As membranas de PVC apresentaram sensibilidade moderada, com razões τ0/τar próximas a 4, permitindo medições com uma resolução média de 10 μs.%-1 para a faixa de 16% de O2 a ar. No caso das membranas em PS, as razões τ0/τar chegam a atingir 50, com resoluções acima de 900 μs.%-1 para concentrações entre 0% e 1% de O2; no entanto, mostram-se de difícil aplicação para concentrações acima de 16%. De modo geral, os elementos produzidos apresentaram tempos de resposta inferiores a 1 s. Assim, possíveis aplicações para estes dispositivos incluem o monitoramento da respiração humana e a detecção de oxigênio residual (e.g.: embalagens alimentícias). Evidenciou-se ainda, uma elevada fotodegradação das membranas perante a excitação na banda B, sendo que o indicador PdTFPP mostrou-se superior aos demais quanto à fotoestabilidade.This research presents the development of sensing membranes for detection of gaseous oxygen by time-resolved phosphorescence as well as the description of a measurement system for performance evaluation of those elements. The transducers are formed by the immobilisation of palladium metalloporphyrins probes (coproporphyrin I, mesoporphyrin IX, deuteroporphyrin IX and meso-Tetrapenta(fluorophenyl) porphyrin) in polymers of poly(vinyl chloride) and polystyrene. A light emitting diode is employed for dye excitation and the phosphorescence is detected by a miniature photomultiplier tube. The production of the membranes as well as their practical parameters such as calibration curves, ageing, response times and light stability are reported. PVC membranes exhibited moderate sensitivity, with ratios τ0/τair near 4, enabling measurements with a resolution of 10 μs.%-1 for the range of 16% of O2 up to 20,5%. For PS membranes, the ratios τ0/τair reached up to 50, with resolutions of up to 900 μs.%-1 considering concentrations between 0% and 1% of O2, however they proved to be of difficult application for concentrations above 16%. Some sensor membranes showed response times below 1 s. Thus, possible applications for these devices include monitoring of human respiration and detection of residual oxygen (e.g.: food packaging). Also, it was observed a high signal degradation when the dyes are excited around their B bands. PdTFPP dye presented more light stability than the others.
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Pellegrino, Jessica. "Développement de deux instruments LIDAR multi-longueurs d'onde et multi-espèces à base de sources paramétriques." Thesis, Paris 6, 2014. http://www.theses.fr/2014PA066531/document.
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La surveillance globale de l’atmosphère et de la pollution de l’air est devenue un enjeu majeur ces dernières années afin d’estimer les conséquences des activités humaines sur notre environnement. Au cours de ces travaux de thèse, l’objectif a été de développer deux instruments LIDARs en détection directe basés sur des émetteurs multi-longueurs d’onde et multi-espèces mettant en œuvre des sources paramétriques optiques innovantes basées sur la technologie NesCOPO (nested cavity optical parametric oscillator) afin de répondre à deux applications : le suivi de la qualité de l’air sur sites industriels et le suivi des gaz à effet de serre depuis l’espace. Un premier instrument multi-espèces a été développé dans le cadre du suivi de la qualité de l’air sur sites industriels, dans la gamme spectrale 3,3 à 3,8 µm, et dédié à des mesures de concentrations moyennes le long de la ligne de visée pour des portées de l’ordre de la centaine de mètres. Une démonstration du potentiel multi-espèces de l’instrument a été réalisée en mesurant simultanément les concentrations en méthane et en vapeur d’eau atmosphériques. A partir d’une source optique existante dédiée à la mesure du dioxyde de carbone seul, un second émetteur multi-longueurs d’onde et multi-espèces a été développé dans une gamme spectrale autour de 2 µm. Son potentiel pour la mesure des gaz à effets de serre depuis l’espace a été étudié En particulier, nous avons démontré que cet émetteur permet de mesurer trois gaz atmosphériques : CO2, H2O et CH4. Une architecture globale d’instrument intégrant cet émetteur a été proposée, afin de réaliser des mesures résolues spatialement, avec des portées de quelques km. De plus, un code de simulation a été développé pour estimer les performances de cet instrument en détection directeAtmospheric global monitoring and air quality are major environmental concerns. Global monitoring of some trace and green-house gases would help to understand the consequences of human activities on our environment. The aim of this work is to develop two multi-wavelengths and multi-species direct detection lidar instruments, based on the same laser transmitter baseline approach - an innovative parametric source, the Nested Cavity optical parametric oscilator-and to target two applications: the monitoring of air quality on industrial sites and the monitoring of greenhouse gases from space. The first instrument was designed for industrial plant monitoring applications, in the 3.3-3.8µm, and allows the measurement of multi-species mean concentrations along the line of sight, over a range of around a hundred meters. This instrument was implemented for simultaneous measurements of atmospheric methane and water vapour.The second instrument targets the green-house gases measurement from space applications. In this frame, a new multi-wavelengths and multi-species emitter was developed at 2 µm for space applications. We have demonstrated that this new emitter could address three species: carbon dioxide, water vapor and methane, and studied his potential for space-borne applications.. The architecture of a complete range-resolved instrument based on this transmitter was proposed. Moreover, a numerical algorithm was developed to estimate the instrument’s performances with a direct detection scheme