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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.
231

Uma perspectiva sociocultural para a introdução de conceitos de física quântica no ensino médio : análise das interações discursivas em uma unidade didática centrada no uso do interferômetro virtual de Mach-Zehnder

Telichevesky, Lucas January 2015 (has links)
Este trabalho relata a produção, implementação e avaliação de um curso sobre física quântica destinado a alunos do Ensino Médio. A unidade didática foi inspirada nas propostas de Ostermann et al. (2009) e Pessoa Jr. (1997, 2003). Ela introduz a física quântica considerando a óptica ondulatória como um contexto para introduzir algumas analogias conceituais básicas para conceitos fundamentais da física quântica. O conceito central desta abordagem é a dualidade onda-partícula e o Interferômetro Virtual de Mach-Zehnder (IVMZ) é utilizado como sua ferramenta didática principal ou, em termos vygotskyanos, ferramenta de mediação. A proposta foi aplicada no formato de uma oficina extracurricular em uma escola privada de Porto Alegre no Brasil. Um dos professores de Física da escola se engajou e colaborou com este projeto. As aulas ocorreram entre os meses de Outubro e Novembro de 2013, em encontros semanais de uma hora. A perspectiva sociocultural de Vygotsky foi utilizada para embasar as aulas do curso. A translinguística de Bakhtin e os conceitos vygotskyanos foram utilizados para a análise das falas dos estudantes durante as atividades do curso. Nesta perspectiva analítica buscamos compreender como os estudantes elaboram estratégias discursivas para entender o conceito de dualidade onda-partícula, analisando a importância das interações com parceiros mais capazes (como professores), textos, simulações e outras ferramentas didáticas. Os resultados indicam que os estudantes desenvolveram algum domínio das ferramentas mediacionais necessárias para compreender a dualidade onda-partícula em um nível satisfatório. O Interferômetro Virtual de Mach-Zehnder, os roteiros exploratórios e os professores mostraram-se importantes para tornar mais efetivas as experiências de aprendizagem dos estudantes. / This dissertation reports the development, implementation and evaluation of a quantum physics course directed to high school students. The course was conceived inspired in proposals of Ostermann et al. (2009) and Pessoa Jr. (1997, 2003). It introduces quantum physics considering wave optics as a context to introduce some basic conceptual analogies to quantum fundamental concepts. The core concept of this approach is the wave-particle duality and the Virtual Mach-Zehnder Interferometer (VMZI) is used as its main didactical tool or, in vygotskyan terms, a mediational tool. The course was applied as an extracurricular workshop in a private school from Porto Alegre, Brazil. One of the school´s Physics teacher collaborated and engaged in this project. The classes took place between October and November 2013, in a set of one-hour weekly meetings. Vygotsky´s sociocultural perspective is adopted to ground the practices of the course. Both Bakhtin´s translinguistics and Vygotsky’s concepts were used to perform the analysis of students’ utterances along didactical activities at the classes. In this analytical framework, we try to understand how students elaborate discursive strategies to understand the concept of wave-particle duality, analyzing the importance of interaction with more experienced peers (like teachers), texts, simulation and other teaching tools. The results indicate that the students developed some mastery of mediational means needed to understand the wave-particle duality at a satisfactory level. The Virtual Mach-Zehnder Interferometer, the exploratory guides and the teachers were important to enhance the students’ learning experiences.
232

Radial velocities in low mass stars: improving the wavelength solution of astronomical spectrographs and understanding stellar noise

Bauer, Florian Franziskus 09 December 2016 (has links)
No description available.
233

A novel optical bio-chemical sensor based on hybrid nanostructures of Bowtie nanoantennas and Fabry-Perot Interferometer / Un nouveau capteur optique et biochimique basé sur des nanostructures hybrides de nanoantennes papillons et d'interféromètres de Fabry-Perot

Liu, Huanhuan 20 November 2013 (has links)
Aujourd'hui, la préoccupation croissante pour l'analyse environnementale et le contrôle de la qualité des aliments, ainsi que les besoins médicaux tels que le diagnostic rapide en cas de situations d'urgence, entraîne un besoin croissant de nouvelles générations de capteurs chimiques et biologiques. Ces dispositifs doivent avoir une haute sensibilité et fiabilité, ils doivent permettre une détection spécifique de molécules et une détection parallèle de différentes molécules, tout en étant bas coût, portables, rapides et faciles à utiliser. Ainsi, une tendance générale se porte sur les capteurs biochimiques intégrés sur puce, sans marqueur, et compatibles avec les procédés standard des micro-technologies. Les dispositifs diélectriques photoniques à base de silicium poreux et les nanostructures métalliques à résonances plasmoniques sont de bons candidats pour répondre aux exigences ci-dessus. Le silicium poreux est un matériau biocompatible, avec une énorme surface spécifique entrainant un gain de la sensibilité de plusieurs ordres de grandeur par rapport aux matériaux massifs ; en outre, son indice de réfraction et son épaisseur peuvent être facilement ajustés, permettant la réalisation d'une grande variété de dispositifs photoniques. Les nanostructures métalliques offrent un fort confinement et une forte amplification du champ électromagnétique dans des régions sub-longueur d'onde, ce qui conduit à des sensibilités élevées ; combinées avec d’autres mécanismes de détection comme la fluorescence, le Raman ou la spectroscopie IR, elles ont déjà démontré un gain important du potentiel pour la détection. La réalisation d'un dispositif hybride combinant ces deux éléments est très intéressant, car il peut offrir les avantages des deux éléments ; la structure photonique pourrait aussi façonner la résonance plasmonique pour le développement de dispositifs ultrasensibles à largeur de raie de résonance étroite tout en ayant une profondeur de détection accrue. Dans ce contexte, l'objectif de cette thèse est d'explorer les défis de cette solution en considérant la conception, la réalisation, la caractérisation et le potentiel de dispositifs hybrides photoniques/plasmoniques qui exploitent le couplage entre la résonance plasmonique de surface localisée d'un réseau d'antennes papillon et les modes photoniques d'un interféromètre en silicium poreux. / Nowadays, the increasing concern for environmental analysis and food quality control, as well as medical needs such as fast diagnosis in case of emergency events, leads to a growing need for new generations of chemical and biological sensors. These devices should have high sensitivity and reliability, perform specific detection of molecules and enable multiple parallel sensing, while being cheap, portable, fast and easy to use. Thus, a general trend tends towards bio-chemical sensors which are on-chip integrated, label-free, and compatible with standard micro-technologies. Photonic dielectric devices based on porous silicon and metallic nanostructures based on plasmon resonances are good candidates to fulfill the above requirements. Porous silicon is a biocompatible material, with a huge specific surface providing a sensitivity enhancement by several orders of magnitude compared to bulk materials; furthermore, its refractive index and thickness can be easily tuned, enabling for the realization of a large variety of photonic designs. Metallic nanostructures provide high confinement and strong field enhancement in sub-wavelength regions, leading to high sensitivities; combined with fluorescence or other sensing mechanisms such as Raman or IR spectroscopy, they have already demonstrated increased sensing potential. The realization of a hybrid device combining both elements would be highly interesting, since it could yield the advantages of both elements, and the photonic structure could shape the plasmonic resonance to develop ultrasensitive devices with narrow resonance linewidth and increased sensing depth. In this context, we realized and studied a novel hybrid photonic / plasmonic device exploiting the coupling between the surface plasmon resonance of a bowtie nano - antenna (NAs) array and the photonic modes of porous silicon (PSi) interferometer. We designed and fabricated a NAs array with resonance wavelength ~ 1.3μm on a homogeneous PSi interferometer. A thin spacing silica layer with controllable density protects the pores of PSi layer and provides a smooth surface for the fabrication of NAs. The coupling mechanisms of two elements - NA array and interferometer, are studied with 2 models, which are interferometer approach and resonator approach. The interferometer approach is focused on studying the influence of NAs array as a homogeneous layer on the fringes shift of the interferometer. For resonator approach, the coupled mode theory is applied. With these models, strong coupling between both elements are discovered: splitting. In the case of viii smaller environment variation, the hybrid device gains 5-10 fold sensitivity enhancement vs. 2 elements alone. The controllable SiO2 layer allows us to sense the index variation within PSi interferometer. This opens a route towards double parallel sensing. The development of the theoretical models under different environment is ongoing, which is expected to utilize the strong coupling for the sensing. A further investigation of the sensing potential of the hybrid device would be expected. And the 2 elements constituting the hybrid structure – the interferometer and the NA array – could be modified in order to enlarge the study to a wider family of devices with greater properties and performances. This work was performed within the framework of the program “Groups of Five Ecoles Centrales” between China Scholarship Council (CSC) and Lyon Institute of Nanotechnologies (INL, CNRS UMR 5270). The project has been supported by the Nanolyon technology platform at INL.
234

Design, simulation and fabrication of a vertical microscanner for phase modulation interferometry - Application to optical coherence tomography system for skin imaging / Design, simulation et fabrication d'un micro-scanner vertical pour l'inférométrie à modulation de phase

Lullin, Justine 17 December 2015 (has links)
Cette thèse décrit le design, la simulation et la fabrication d’une matrice 4x4 de micro-miroirs actionnée verticalement et munie d’un capteur de position. Le micro-scanneur vertical a pour vocation à être intégré au sein d’un micro-interféromètre de Mirau de type matriciel, réalisé àbase de composants micro-optiques fabriqués grâce à des méthodes collectives. Le mouvement du micro-scanneur, développé dans cette thèse, génère un signal de référence utilisé pour l’implémentation de l’interférométrie à modulation de phase dans un système de tomographie par cohérence optique (OCT). Dans un premier temps, la thèse introduit le besoin d’un système d’imagerie adapté pour la détection précoce des cancers de la peau et établit les spécifications optiques requises par cette application. A partir de ces spécifications, le design du système OCT basé sur le micro-interféromètre de Mirau est présenté. En parallèle, l’état de l’art des technologies de micro-actionnement est décrit et un actionnement électrostatique à base de peignes interdigités est choisi pour actionner et lire la position de la matrice de micro-miroirs. En effet ce type d’actionnement bénéficie d’une bonne compatibilité avec le design du micro-interféromètre de Mirau. Dans un second temps, le cœur de la thèse expose le développement du micro-scanneur vertical, c.à.d le design et les simulations ainsi que la fabrication et la caractérisation. / This thesis describes the design, simulation and fabrication of a vertically actuated 4x4 array ofmicromirrors with embedded position sensing function. The vertical microscanner is meant to beintegrated within an array-type Mirau microinterferometer realized with optical microcomponentsfabricated using collective techniques. The microscanner, developed in this thesis, provides areference signal that is used for the implementation of phase modulation interferometery in an opticalcoherence tomography (OCT) system. This thesis first introduces the need for adapted imagingsystems for the early diagnosis of skin cancer and establishes the optical specifications requiredby this specific application. Based on these specifications, the design of the OCT system based onthe Mirau microinterferometer is presented. In parallel, the state of the art of the microactuationtechnologies is discussed and comb drive electrostatic actuation is chosen, for its compatibilitywith the design of the Mirau microinterferometer, to actuate and sense the position of the array ofmicromirrors. Then, the core of the thesis deals with the development of the vertical microscanner,i.e. its design and simulations, its fabrication and its characterization.
235

Micro-fabrication of a Mach-Zehnder interferometer combining laser direct writing and fountain pen micropatterning for chemical/biological sensing applications.

Kallur, Ajay 05 1900 (has links)
This research lays the foundation of a highly simplified maskless micro-fabrication technique which involves incorporation of laser direct writing technique combined with fountain pen based micro-patterning method to fabricate polymer-based Mach-Zehnder interferometer sensor arrays' prototype for chemical/biological sensing applications. The research provides methodology that focuses on maskless technology, allowing the definition and modification of geometric patterns through the programming of computer software, in contrast to the conventional mask-based photolithographic approach, in which a photomask must be produced before the device is fabricated. The finished waveguide sensors are evaluated on the basis of their performance as general interferometers. The waveguide developed using the fountain pen-based micro-patterning system is compared with the waveguide developed using the current technique of spin coating method for patterning of upper cladding of the waveguide. The resulting output power profile of the waveguides is generated to confirm their functionality as general interferometers. The results obtained are used to confirm the functionality of the simplified micro-fabrication technique for fabricating integrated optical polymer-based sensors and sensor arrays for chemical/biological sensing applications.
236

Online korekce geometrických a rozměrových odchylek / Online correction of geometric and dimensional deviations

Plichta, Zbyněk January 2017 (has links)
The thesis deals with a development and application of laser interferometer system for the online error calibration of CNC machine tool. The term „online“ means, that laser interferometer is permanently built in the machine tool. Therefore particular error measurements can be done in very short time period.
237

Měření obrobků na obráběcích strojích pomocí obrobkové sondy / Measurement of workpieces on machine tools using a touch probe

Velič, Samuel January 2020 (has links)
This diploma thesis deals with the influence of electronic compensation on accuracy of the measurement using the touch probe. The theoretical part concerns touch probes, specifically their classification, principles of working and applications. This part also includes devices used later in the experiment, particularly double ballbar, laser interferometer and LaserTRACER. The Practical part describes an experiment, demonstrating the correlation between the accuracy improvement of the touch probe and the electronic compensation’s level. All measurements were executed in accordance with the norm VDA 5 and were evaluated by the Matlab software. The graphs of reliance tolerance of capability of measurement on the length of the benchmark. At the end of this diploma thesis there are partial conclusions deduced. The deduction is based on generated graphs. The partial conclusions synoptically compare the influence of individual machine´s configurations on the accuracy of the touch probe.
238

Michelsonův interferometr / Michelson's interferometer

Rýc, Jan January 2011 (has links)
The diploma work deals with techniques of optical contactless distance and velocity measurement. A basic summary of the methods are involved. The problematic of interferometric methods for vibration measurements is analysed in detail. It contains division of interferometers, description of their function principles and also chapters dealing with elements used in interferometers such as lasers, photodetectors and elements in the ray optical way - polarizers, retarders, optical isolators. The vibration and length measurement methods are described, as well as the conception of homodyne and heterodyne detection. Part of this work focuses on the quadrature signal processing and on the proposal of algorithm for demodulation of velocity/displacement and undergoing simple motioning object deviation. This algorithm is implemented in Labview and the whole software instrument served also for visualisation of measured data of the interferometer model constructed in the laboratory. The way how to build up a model, its setting and two possible configurations suitable for homodyne detection are described. Model of interferometer is built-up on the optical breadboard. Particular components are fixed by the help of mounts. The model and software enable to measure the velocity and the vibration deviation with the light wavelength exactness. Functionality and the exactness of the laboratory model are verified by vibrometer. Effects on the measurement uncertainty are discussed here and ways how to restrain them are proposed.
239

Nanometrologická vibrometrie / Nanometric vibrometry

Ševčík, Michal January 2013 (has links)
This thesis deals with the precise measurement of distances in nanometer range at ultrasonic frequencies for the purposes of vibrometry. The paper is primary focused on~nanometric displacement measurement methods. First the thesis deals with the physical phenomena based on light in the theoretical section. This includes interference of light, index of refraction, polarization, interferometry and more. Understanding of these physical laws is crucial for design and assembling of the interferometer. Subjects of interferometric method for precise and fast measurement of the nanometric displacement and vibration are discussed. Interferometer components such as lasers, photodetectors and optical elements are described are described in the final part of this section. Practical section of thesis can be divided into two parts. The design and assembling issues are discussed in the first section. Many problems which I had to solve are described. Control software and implementation of the signal processing is the subject of the second part. I met with particular problems such as phase unwrapping. I solved this problem of discontinuous phase field with user written algorithm. Finally the graphical user interface was created. Using assembled interferometer and written software application I measured vibration of Langevin transducer on ultrasonic frequencies.
240

Optický systém pro torzně detekovanou elektronovou spinovou rezonanční spektroskopii / Optical setup for torque detected electron spin resonance spectroscopy

Kern, Michal January 2015 (has links)
Táto diplomová práca sa venuje vylepšeniu spektroskopu Torzne Detegovanej Elektrónovej Spinovej Rezonancie (TDESR) výmenou aktuálnej kapacitnej detekcie výchylky ohybného ramienka za optické metódy. Práca popisuje základy Elektrónovej Spinovej Rezonančnej (ESR) spektroskopie s dôrazom na TDESR a tému magnetizmu jednomolekulových magnetov. Následne je vysvetlená detekcia výchylky ramienka pomocou odrazu laserového zväzku a interferometrie. Všetky kroky nutné k skonštruovaniu spektrometra a jeho uvedenia do prevádzky sú podrobne popísané. Pomocou detekcie odrazu laserového zväzku sme úspešne získali vysoko kvalitné TDESR spektrá kryštálu jednomolekulového magnetu Fe4. Týmto meraním sme dokázali vhodnosť použitia tejto metódy a jej výraznú prevahu nad pôvodnou kapacitnou detekciou, najmä v oblasti kvality, rozlíšenia a rýchlosti. Zároveň sme na ďaľšie vylepšenie TDESR spektrometra navrhli a zostrojili zostavu využívajúcu na detekciu výchylky interferometer.

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