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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.
31

Pattern-integrated interference lithography: single-exposure formation of photonic-crystal lattices with integrated functional elements

Burrow, Guy Matthew 15 June 2012 (has links)
A new type of photolithography, Pattern-Integrated Interference Lithography (PIIL), was demonstrated. PIIL is the first-ever integration of pattern imaging with interference lithography in a single-exposure step. The result is an optical-intensity distribution composed of a subwavelength periodic lattice with integrated functional circuit elements. To demonstrate the PIIL method, a Pattern-Integrated Interference Exposure System (PIIES) was developed that incorporates a projection imaging capability in a novel three-beam interference configuration. The purpose of this system was to fabricate, in a single-exposure step, representative photonic-crystal structures. Initial experimental results have confirmed the PIIL concept, demonstrating the potential application of PIIL in nano-electronics, photonic crystals, biomedical structures, optical trapping, metamaterials, and in numerous subwavelength structures. In the design of the PIIES configuration, accurate motif geometry models were developed for the 2D plane-group symmetries possible via linearly-polarized three-beam interference, optimized for maximum absolute contrast and primitive-lattice-vector direction equal contrast. Next, a straightforward methodology was presented to facilitate a thorough analysis of effects of parametric constraints on interference-pattern symmetries, motif geometries, and their absolute contrasts. With this information, the design of the basic PIIES configuration was presented along with a model that simulates the resulting optical-intensity distribution at the system sample plane. Appropriate performance metrics were defined in order to quantify the characteristics of the resulting photonic-crystal structure.
32

Développement d’une source de rayonnement X par diffusion Compton inverse sur l'accélérateur ELSA et optimisation à l'aide d'un système d'empilement de Photons / Development of a multi-keV Compton Source on ELSA linac and optimization with a photons piling-up sytem

Chaleil, Annaïg 03 November 2016 (has links)
La diffusion Compton inverse est l’interaction entre un photon et un électron de haute énergie. Il en résulte l’émission d’un nouveau photon d’énergie supérieure à celle du photon incident suivant la trajectoire de l’électron. Ces propriétés rendent possible la création d’une source de rayonnement X hautement directive, monochromatique accordable dans une large gamme spectrale. Il suffit d’accélérer les électrons sur quelques mètres pour leur faire gagner l’énergie minimale requise. Les photons proviennent d’une chaîne laser fortement amplifiée. Une telle source est donc relativement compacte, peu couteuse à mettre en oeuvre et facilement accessible aux utilisateurs. Elle est particulièrement adaptée aux besoins des musées ou des hôpitaux pour des applications comme l’analyse d’oeuvres historiques ou la radiothérapie. L’objectif de cette thèse est de mettre en oeuvre une source de rayonnement X par diffusion Compton inverse en bout de ligne de l’accélérateur ELSA (Electrons et Laser, Sources X et applications). L’installation ELSA comprend un accélérateur linéaire d’électrons appartenant à la Direction des Applications Militaires du Commissariat à l’Energie Atomique à Bruyères-le-Châtel (CEA DAM). Le but est de produire des impulsions de rayonnement X ultra-courtes dans une gamme énergétique allant de 10 à 100 keV. Elle servira notamment à la caractérisation de détecteurs à réponse ultra-rapide développés à la DAM. Un système optique destiné à augmenter le flux de rayonnement X produit a été développé. Il consiste à replier la trajectoire du laser pour empiler les impulsions au point d’interaction. Dans le même but, une mise à niveau de l’installation à été réalisée afin d’augmenter l’énergie des électrons de 18 à 30 MeV. Les résultats expérimentaux ont enfin été comparés aux résultats obtenus à l’aide de simulations PIC 3D. / X-ray sources based on inverse Compton scattering process produce tunable near-monochromatic and highly directive X-rays. Recent advances in laser and accelerator technologies make the development of such very compact hard X-ray sources possible. These sources are particularly attractive in several applications such as medical imaging, cancer therapy or culture-heritage study, currently performed in size-limited infrastructures. The main objective of this thesis is the development of an inverse Compton scattering source on the ELSA linac of CEA at Bruyères-le-Châtel as a calibration tool for ultra-fast detectors.A non-resonant cavity was designed to multiply the number of emitted X-ray photons. The laser optical path is folded to pile-up laser pulses at the interaction point, thus increasing the interaction probability. Another way of optimizing the X-ray yield consists in increasing the electron bunch density at the interaction point, which is strongly dependent on the electron energy. A facility up-grade was performed to increase the electron energy up to 30 MeV. The X-ray output gain obtained thanks to this system was measured and compared with calculated expectations and 3D PIC simulations.
33

Contributions to the design of Fourier-optical modulation systems based on micro-opto-electro-mechanical tilt-mirror arrays

Roth, Matthias 27 October 2020 (has links)
Spatial Light Modulators (SLMs) based on Micro-Opto-Electro-Mechanical Systems (MOEMS) are increasingly being used in various fields of optics and enable novel functionalities. The technology features frame rates from a few kHz to the MHz range as well as resolutions in the megapixel range. The field continues to make rapid progress, but technological advancements are always associated with high expenditure. Against this background, this dissertation addresses the question: What contribution can optical system design make to the further development of MOEMS-SLM-based modulation? A lens is a simple example of an optical system. This dissertation deals with system design based on Fourier optics in which the wave properties of light are exploited. On this basis, arrays of micromirrors can modulate light properties in a spatially resolved manner. For example, tilt-mirrors can control the intensity distribution in an image plane. In this dissertation variations of the aperture required for this are investigated. In addition to known absorbing apertures, phase filters in particular are investigated, which apply a spatially distributed delay effect to the light wave. This dissertation proposes the combination of MOEMS-SLMs with static, pixelated elements in the same system. These may be pixelated phase masks, also known as diffractive optical elements (DOEs). Analogously, pixelated polarizer arrays and absorbing photomasks exist. The combination of SLMs and static elements allows new degrees of freedom in system design. This thesis proposes new modulation systems based on MOEMS tilt-mirror SLMs. These systems use analog tilt-mirror arrays for the simultaneous modulation of intensity and phase as well as intensity and polarization. The proposed systems thus open up new possibilities for MOEMS-based spatial light modulation. Their properties are validated and investigated by numerical simulations. System properties and limitations are derived from these near and far field simulations. This dissertation shows that the modulation of different MOEMS-SLM types can be fundamentally changed by system design. Piston mirror arrays are classically used for phase modulation and tilt-mirror arrays for intensity modulation. This thesis proposes the use of subpixel phase structures. Their use approximately provides tilt-mirrors with the phase-modulating effect of piston-mirrors. In order to achieve this, a new optimization method is presented. Piston-mirror arrays are available only to a limited extent. By contrast, tilt-mirror arrays are well established. In combination with subpixel phase features, tilt-mirrors may replace piston-mirrors in some applications. These and other challenges of MOEMS-SLM technology can be adequately addressed on the basis of system design. / Räumliche Lichtmodulatoren (Spatial Light Modulators, SLMs) auf Basis von Mikro-Opto-Elektro-Mechanischen Systemen (MOEMS) finden zunehmend Anwendung in verschiedensten Teilgebieten der Optik und ermöglichen neuartige Funktionalitäten. Die Technik ermöglicht Frameraten von einigen kHz bis in den MHz-Bereich sowie Auflösungen bis in den Megapixelbereich. Der Fachbereich macht nach wie vor rasche Fortschritte, technologische Weiterentwicklungen sind aber stets mit hohem Aufwand verbunden. Vor diesem Hintergrund widmet sich diese Arbeit der Frage: Welchen Beitrag kann optisches Systemdesign zur Weiterentwicklung der MOEMS-SLM-basierten Modulation leisten? Bereits eine Linse stellt ein Beispiel für ein optisches System dar. Diese Dissertation beschäftigt sich mit Systemdesign auf Basis der Fourier-Optik, bei der die Welleneigenschaften des Lichts genutzt werden. Auf dieser Basis können Arrays von Mikrospiegeln die flächige Verteilung von Licht einstellen. Beispielsweise können Kippspiegel die Intensitätsverteilung in einer Bildebene steuern. In dieser Dissertation werden Variationen der dafür nötigen Apertur untersucht. Neben bekannten absorbierenden Blenden werden insbesondere Phasenfilter untersucht, welche eine flächig verteilte Verzögerungswirkung auf die Lichtwelle aufbringen. Diese Dissertation schlägt die Kombination von MOEMS-SLMs mit statischen, pixelierten Elementen im selben System vor. Hierbei kann es sich um pixelierte Phasenmasken handeln, auch bekannt als diffraktive optische Elemente (DOEs). Analog existieren pixelierte Polarisatorarrays und absorbierende Fotomasken. Die Kombination von SLMs und statischen Elementen ermöglicht neue Freiheiten im Systemdesign. Diese Arbeit schlägt neue Modulationssysteme auf Basis von MOEMS-Kippspiegel-SLMs vor. Diese Systeme nutzen analoge Kippspiegelarrays für die simultane Modulation von Intensität und Phase sowie von Intensität und Polarisation. Die vorgeschlagenen Systeme eröffnen damit neue Möglichkeiten für die MOEMS-basierte Flächenlichtmodulation. Ihre Eigenschaften werden mithilfe von numerischen Simulationen validiert und untersucht. Aus diesen Nah- und Fernfeldsimulationen werden Systemeigenschaften und Limitierungen abgeleitet. Es wird in dieser Arbeit gezeigt, dass die Modulation verschiedener MOEMS-SLM-Typen auf Basis des Systementwurfs fundamental verändert werden kann. Senkspiegelarrays werden klassischerweise zur Modulation der Phase eingesetzt und Kippspiegelarrays zur Modulation der Intensität. Diese Arbeit schlägt die Nutzung von Subpixel-Phasenstrukturen vor. Diese verleihen Kippspiegeln näherungsweise die phasenmodulierende Wirkung von Senkspiegeln. Um dies zu erreichen, wird ein neuartiges Optimierungsverfahren vorgestellt. Senkspiegelarrays sind nur in geringem Umfang verfügbar. Im Gegensatz dazu sind Kippspiegelarrays gut etabliert. In Kombination mit Subpixel-Phasenstrukturen könnten Kippspiegel in einigen Anwendungen Senkspiegel ersetzen. Diese und andere Herausforderungen der MOEMS-SLM-Technologie lassen sich auf der Grundlage des Systemdesigns adäquat adressieren.
34

Point-of-Care High-throughput Optofluidic Microscope for Quantitative Imaging Cytometry

Jagannadh, Veerendra Kalyan January 2017 (has links) (PDF)
Biological research and Clinical Diagnostics heavily rely on Optical Microscopy for analyzing properties of cells. The experimental protocol for con-ducting a microscopy based diagnostic test consists of several manual steps, like sample extraction, slide preparation and inspection. Recent advances in optical microscopy have predominantly focused on resolution enhancement. Whereas, the aspect of automating the manual steps and enhancing imaging throughput were relatively less explored. Cost-e ective automation of clinical microscopy would potentially enable the creation of diagnostic devices with a wide range of medical and biological applications. Further, automation plays an important role in enabling diagnostic testing in resource-limited settings. This thesis presents a novel optofluidics based approach for automation of clinical diagnostic microscopy. A system-level integrated optofluidic architecture, which enables the automation of overall diagnostic work- ow has been proposed. Based on the proposed architecture, three different prototypes, which can enable point-of-care (POC) imaging cytometry have been developed. The characterization of these prototypes has been performed. Following which, the applicability of the platform for usage in diagnostic testing has been validated. The prototypes were used to demonstrate applications like Cell Viability Assay, Red Blood Cell Counting, Diagnosis of Malaria and Spherocytosis. An important performance metric of the device is the throughput (number of cells imaged per second). A novel microfluidic channel design, capable of enabling imaging throughputs of about 2000 cells per second has been incorporated into the instrument. Further, material properties of the sample handling component (microfluidic device) determine several functional aspects of the instrument. Ultrafast-laser inscription (ULI) based glass microfluidic devices have been identi ed and tested as viable alternatives to Polydimethylsiloxane (PDMS) based microfluidic chips. Cellular imaging with POC platforms has thus far been limited to acquisition of 2D morphology. To potentially enable 3D cellular imaging with POC platforms, a novel slanted channel microfluidic chip design has been proposed. The proposed design has been experimentally validated by performing 3D imaging of fluorescent microspheres and cells. It is envisaged that the proposed innovation would aid to the current e orts towards implementing good quality health-care in rural scenarios. The thesis is organized in the following manner : The overall thesis can be divided into two parts. The first part (chapters 2, 3) of the thesis deals with the optical aspects of the proposed Optofluidic instrument (development, characterization and validations demonstrating its use in poc diagnostic applications). The second part (chapters 4,5,6) of the thesis details the microfluidic sample handling aspects implemented with the help of custom fabricated microfludic devices, the integration of the prototype, func-tional framework of the device. Chapter 2 introduces the proposed optofluidic architecture for implementing the POC tool. Further, it details the first implementation of the proposed platform, based on the philosophy of adapting ubiquitously available electronic imaging devices to perform cellular diagnostic testing. The characterization of the developed prototypes is also detailed. Chapter 3 details the development of a stand-alone prototype based on the proposed architecture using inexpensive o -the-shelf, low frame-rate image sensors. The characterization of the developed prototype and its performance evaluation for application in malaria diagnostic testing are also presented. The chapter concludes with a comparative evaluation of the developed prototypes, so far. Chapter 4 presents a novel microfludic channel design, which enables the enhancement of imaging throughput, even while employing an inexpensive low frame-rate imaging modules. The design takes advantage of radial arrangement of microfludic channels for enhancing the achievable imaging throughput. The fabrication of the device and characterization of achievable throughputs is presented. The stand-alone optofluidic imaging system was then integrated into a single functional unit, with the proposed microfluidic channel design, a viscoelastic effect based micro uidic mixer and a suction-based microfluidic pumping mechanism. Chapter 5 brings into picture the aspect of the material used to fabricate the sample handling unit, the robustness of which determines certain functional aspects of the device. An investigative study on the applicability of glass microfluidic devices, fabricated using ultra-fast laser inscription in the context of the microfluidics based imaging flow cytometry is presented. As detailed in the introduction, imaging in poc platforms, has thus far been limited to acquisition of 2D images. The design and implementation of a novel slanted channel microfluidic chip, which can potentially enable 3D imaging with simplistic optical imaging systems (such as the one reported in the earlier chapters of this thesis) is detailed. A example application of the proposed microfludic chip architecture for imaging 3D fluorescence imaging of cells in flow is presented. Chapter 6 introduces a diagnostic assessment framework for the use of the developed of m in an actual clinical diagnostic scenario. The chapter presents the use of computational signatures (extracted from cell images) to be employed for cell recognition, as part of the proposed framework. The experimental results obtained while employing the framework to identify cells from three different leukemia cell lines have been presented in this chapter. Chapter 7 summarizes the contributions reported in this thesis. Potential future scope of the work is also detailed.
35

Optický zesilovač v laboratorní výuce / Optical amplifier in laboratory practice

Šustr, Pavel January 2009 (has links)
The aim of this thesis is to introduce to reader the application and use of optical EDFA amplifiers in optical transmission and to show wiring and practical test, including measurements on amplifier. The aim of this thesis is to propose the use of optical amplifier in laboratory practice for subject Optical networks. The thesis briefly introduces the problems of data transmissions through optical fibers with a focus on the use of optical amplifiers. The basic characteristic of optical transmission paths and the reasons for the use of optical amplifiers are described here. One entire chapter is devoted to distinction of optical amplifiers. Amplifiers can be divided according to location in the transmission path to the booster, in-line and pre-amplifiers and according to the used of amplifying technology to optical amplifiers with subsidies, semiconductor optical amplifiers and Raman optical amplifiers. The factors affecting the efficiency of optical amplifiers, such as noise and the level of saturated power are mentioned here too. The different types of optical amplifiers from the two producers are also described. From these amplifiers was chosen EDFA CzechLight Amplifier from Optokon to be used for the laboratory exercise in the subject of Optical networks. The use of EDFA optical amplifiers in optical transmission lines is mentioned here too. These amplifiers can be used in telecommunications transmission systems and for data transmission over long distances. They will find use in WDM transmission systems and cable TV distribution through the optical fiber to the end users. Practical measurements were performed on optical amplifier CLA-PB01F. In the transmission route was located attenuator and the dependence of output power to input signal power was measured. The amplification course was linear in the range of input values provided by the manufacturer. Laboratory exercise for the subject of Optical networks is aimed at preacquaintance of students with problems EDFA optical amplifiers and practical measurements with the optical amplifier CLA-PB01F. Students acquire basic theoretical knowledge of the issue and verify the functionality of optical amplifiers on a specific exercise. This work is destined for all who wish to get basic knowledge of optical amplifiers, their characteristics and possibilities of their use in optical transmission lines.
36

Etude de la stabilité et de la précision des modèles utilisés dans la correction des effets de proximité optique en photolithographie / Study of the impact of different physical parameters during OPC model creation for 65nm and 45nm technologies

Saied, Mazen 30 September 2011 (has links)
À l’heure actuelle, les modèles photochimiques utilisés dans la correction des effets de proximitéoptique (OPC) en photolithographie sont devenus complexes et moins physiques afin de permettre decapturer rapidement le maximum d’effets optiques et chimiques. La question de la stabilité de tels modèlespurement empiriques est devenue d’actualité. Dans ce mémoire, nous avons étudié la stabilité desmodèles photochimiques actuels en examinant les différentes causes d’instabilité vis-à-vis des paramètresdu procédé. Dans la suite, nous avons développé une méthode perturbative permettant d’évaluer le critèrede la stabilité. L’obtention de modèles simples et stables nous conduit à séparer les effets optiques desautres effets chimiques. De plus, les approximations utilisées dans la modélisation des systèmes optiquesopérant à grande ouverture numérique entraînent des erreurs résiduelles pouvant dégrader la précisionet la stabilité des modèles OPC. Ainsi, nous nous sommes intéressés à étudier les limites de validitéde l’approximation de Kirchhoff, méthode qui, jusqu’à présent, est la plus utilisée dans la modélisationdu champ proche d’un masque. D’autres méthodes semi-rigoureuses, permettant de modéliser les effetstopographiques, ont été également évaluées. Ces méthodes approchées permettent de gagner en précisionmais dégradent le temps de calcul. Nous avons ainsi proposé différentes façons de corriger les effetstopographiques du masque, tout en gardant l’approximation de Kirchhoff dans la modélisation de la partieoptique. Parmi les méthodes proposées, nous exploitons celle permettant de réduire les erreurs liéesaux effets topographiques du masque par l’intermédiaire d’un second modèle empirique. Nous montronsque pour garantir une précision adéquate, il est nécessaire d’augmenter la complexité du modèle en rajoutantdes termes additionnels. Enfin, pour garantir la stabilité numérique du modèle empirique, nousintroduirons une nouvelle méthode approchée hybride rapide et précise, la méthode des multi-niveaux,permettant d’inclure les effets topographiques par décomposition multi-niveaux du masque fin et discuteronsses avantages et ses limites. / At present, common resist models utilized in photolithography to correct for optical proximity effects(OPC) became complex and less physical in order to capture the maximum of optical and chemical effectsin shorter times. The question on the stability of such models, purely empirical, become topical. In thisthesis, we study the stability of existing OPC models by examining the origins of model instability towardsprocess parameters. Thus, we have developed a perturbative method in order to evaluate the stabilitycriterion. However, achieving stable and simple models needs a separation between optical and otherchemical effects. Besides, multiple approximations, widely utilized in the modeling of optical systemsoperating at high numerical aperture, lead to residual errors which can degrade OPC model accuracyand stability. Thus, we were interested to study the limits of validity of the Kirchhoff approximation,a method which, so far, is the most commonly used in mask near-field modeling. Other semi-rigorousmethods for mask topography effect modeling were also evaluated. These approximate methods canimprove the accuracy but degrades the run time. We then suggested different techniques to correct formask topography effects, while keeping the Kirchhoff approximation in the modeling of the optical part.Among them, we showed that errors due to mask topography effects can be partially captured by asecond empirical model. However, in order to ensure a good accuracy, it is necessary to increase themodel complexity by using more additional empirical terms. Finally, in order to achieve a numericalstability of the empirical model, we introduced a new hybrid fast and accurate method, the multi-levelmethod, which allows us to correct for mask topography effects through a multi-level decomposition ofthe thin mask and discussed its advantages and drawbacks.

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