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Liang, Yuanxin. "Respiration monitoring with a fibre optic sensor." Swinburne Research Bank, 2008. http://hdl.handle.net/1959.3/47121.
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Thesis (PhD) - Swinburne University of Technology, Faculty of Engineering and Industrial Sciences, Centre for Atom Physics an Ultra-fast Spectroscopy, 2008.A thesis submitted for the degree of Master of Engineering, Centre for Atom Physics an Ultra-fast Spectroscopy, Faculty of Engineering and Industrial Sciences, Swinburne University of Technology, 2008. Typescript. Bibliography: p. 143-149.
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Cheng, Sau Kuen. "Real-time optical fibre sensing of phytoplankton for studies in size distribution and concentration." HKBU Institutional Repository, 1996. http://repository.hkbu.edu.hk/etd_ra/56.
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Boldyreva, Ekaterina. "Mesures réparties par réflectométrie fréquentielle sur fibre optique." Phd thesis, Toulouse, INPT, 2016. http://oatao.univ-toulouse.fr/18709/1/Boldyreva_Ekaterina.pdf.
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Les travaux de la présente thèse concernent l’étude théorique et la réalisation d’un Capteur réparti à Fibres Optiques fondé sur la réflectométrie fréquentielle et la rétrodiffusion de Rayleigh. La genèse de cette méthode remonte aux années 80 pour les mesures distribuées. Il y a un peu plus d’une dizaine d’années qu’elle a été mise en œuvre secrètement pour les meures réparties (continument sensibles) par la société américaine « Luna Innovations ». Cette approche permettant de réaliser des profils continus le long de la fibre des paramètres environnants (température et déformation principalement) offre une très bonne résolution spatiale ainsi qu’une résolution de mesure fine et présente donc un grand intérêt pour de nombreuses applications, venant ainsi en complément des techniques reposant sur la diffusion Raman ou Brillouin. L'aspect théorique de cette méthode dite OFDR Rayleigh a été analysé. Pour effectuer une mesure profilométrique il est nécessaire de déterminer simultanément deux informations : la distance physique allant de l’entrée de la fibre jusqu'au point où un paramètre physique à mesurer a été appliqué, et le paramètre physique proprement dit. Pour réaliser cette mesure un lien entre l'influence du paramètre d’influence et le changement d'indice du cœur de la fibre sous test doit être exploité. Il s’agit donc des sensibilités de mesure, mais aussi de l’influence de l’environnement sur le chemin optique parcouru, et donc sur la localisation précise des points de mesure. Ces différents aspects ont donc été analysés et rapportés dans le présent mémoire. Pour mettre en œuvre cette technique fréquentielle, et en particulier son traitement de signal, relativement complexe, deux méthodes différentes ont été proposées : la première dite « corrélationnelle » (mise en œuvre par « Luna Innovations » mais très peu documentée) et la méthode « tensorielle » proposée uniquement dans le cadre de la présente étude. Etant fondée sur les mesures répétitives des décalages spectraux induits par le paramètre physique à mesurer le long de la fibre, la méthode corrélationnelle est plus universelle, s’adressant à tous types de paramètres d’influence. Pourtant, elle s’avère moins précise du fait d'une erreur systématique dans le calcul des décalages spectraux. La méthode tensorielle, quant à elle, fournit un résultat plus précis, cependant elle n'est applicable que pour les mesures de déformations, puisque reposant sur l'effet élasto-optique dans le cœur de la fibre. Une procédure de traitement de signal a ensuite été élaborée pour les deux méthodes précitées, la corrélationnelle et la tensorielle. Les performances capacités de l'appareil dont nous disposons, Luna OBR 4600, ont également été montrées, tant en ce qui concerne les mesures de température que de déformations. Un banc expérimental mettant en œuvre cette méthode de mesure OFDR-Rayleigh a également été conçu est mis au point au laboratoire. Un logiciel de traitement des données a de fait été élaboré est réalisé. Ce programme a été testé à l'aide d'une simulation et grâce à l’utilisation des données brutes délivrées par l’appareil Luna OBR 4600. Plusieurs tests du programme de traitement des données brutes de cet instrument ont été réalisés. Les résultats de ces tests peuvent être considérés plutôt comme satisfaisants, étant globalement en bon accord avec les résultats fournis directement par l'instrument commercial OBR 4600. Au-delà, de nombreux exemples d'applications innovantes de la méthode Rayleigh OFDR ont été présentés et illustrés. Parmi ceux-ci, citons, le système de détection de fuites de sodium liquide pour la surveillance de fonctionnement des circuits de refroidissement des réacteurs de génération IV que nous avons élaboré, grâce à cette méthode Rayleigh OFDR, et un prototype industriel d'un tel système proposé. Enfin, l’analyse des points pouvant faire l’objet d’améliorations et/ou de marges de progrès a été menée, et est rapportée en fin de mémoire.
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Woelke, Ralf. "Thermodynamische Eigenschaften semirigider Polymere und deren Anwendung in faseroptischen Detektoren - Thermodynamic properties of semirigid polymers and their applications in fibre optical detectors." Gerhard-Mercator-Universitaet Duisburg, 2001. http://www.ub.uni-duisburg.de/ETD-db/theses/available/duett-10092001-105133/.
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In the following thesis the thermotropic phase transition behaviour and structure-property-relations of semiflexible polyesters were investigated. These materials can be used in fibre optical blood-pressure sensors as resonator materials in a Fabry-Perot-Interferometer. PVT-measurements were carried out to determine the thermodynamic parameters alphaV(T) and kappa(P), and the validity of the Ehrenfest equations at glass transition temperatures was verified. These latter investigations showed no thermodynamic second order transition. By using alphaV(T) and kappa(P) for the calculation of the resonator-length-difference, the temperature- and pressure behaviour of the investigated polyesters was simulated. This simulation showed that small variations in the resonator length from increasing pressure agrees with the empirically determined values. An increasing number of methylene groups in the sidechain of the spacer molecule resulted in decreased melting- and glass transition temperature, which revealed the possibility to prepare thin polymer-films with 5-10 micrometer in diameter at low temperatures.
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Bronk, Karen Srour. "Imaging based sensor arrays /." Thesis, Connect to Dissertations & Theses @ Tufts University, 1996.
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Thesis (Ph.D.)--Tufts University, 1996.Adviser: David R. Walt. Submitted to the Dept. of Chemistry. Includes bibliographical references. Access restricted to members of the Tufts University community. Also available via the World Wide Web;
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Haskell, Adam Benjamin. "A Durability and Utility Analysis of EFPI Fiber Optic Strain Sensors Embedded in Composite Materials for Structural Health Monitoring." Fogler Library, University of Maine, 2006. http://www.library.umaine.edu/theses/pdf/HaskellAB2006.pdf.
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Fan, Chenjun. "Fiber optic sensor based on dual ring resonator system /." Online version of thesis, 1992. http://hdl.handle.net/1850/11070.
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Jong, Yeung-dong. "Fiber-optic interferometer for high 1/f noise environments /." Digital version accessible at:, 1998. http://wwwlib.umi.com/cr/utexas/main.
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Utou, Frumence E. "Fiber optic sensors ensuring structural integrity." Thesis, Cape Peninsula University of Technology, 2005. http://hdl.handle.net/20.500.11838/1300.
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Thesis (DTech (Mechnical Engineering))--Cape Peninsula University of Technology, 2005Among the issues that are taken into consideration for many years by Engineers and Technologists is the integrity of the servicing elements in structures and mechanisms. It is a documented phenomenon that after a certain period of time, in service, engineering components tend to change their original state, and begin to develop faults and defects. This includes the original shape distortion due to effects such as bending, twisting, and cracks. The above-sited effects may be caused by the sudden or accumulative effect of overloading, thermal shocks, corrosion etc, which eventually lead to malfunction of these engineering components. The occurrence of the cracks may be as a result of stress variation in excess of different or similar materials; thermal shocks, vibration, etc. A system of structural health monitoring using optical fiber sensors to track down a crack occurrence and its propagation is considered to be a promising method in warning of catastrophic events. Taking advantage of optical fibers' properties and behavior, such as easy interaction with other materials, small size, low weight, corrosion resistance, geometrical flexibility and an inherent immunity to electromagnetic interference, there is potential in adopting the Fiber Optic Sensors (FOS) for structural health monitoring systems. Structural integrity does not confine itself to crack detection only. For example there are many instances where unwanted or excessive displacement may occur. Optical fibers play an important role in proximity sensing as evidenced in the literature [49] to [54] and available commercial systems. However it is felt that FOS displacement sensors may suffer in measurement accuracy due to in situ conditions.
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Klemba, Francielli. "Sensores óticos a fibra aplicados à área de petróleo." Centro Federal de Educação Tecnológica do Paraná, 2005. http://repositorio.utfpr.edu.br/jspui/handle/1/105.
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Este trabalho descreve a produção de redes de Bragg e de período longo em fibras óticas, e a caracterização destas redes como dispositivos sensores na detecção de hidrocarbonetos que fluem em polidutos, bem como na monitoração de sua temperatura. O trabalho foi realizado no Laboratório de Laser da UTFPR. As redes de período longo foram produzidas pela aplicação ponto-a-ponto do arco elétrico de uma máquina de emendas de fibras óticas e caracterizadas como sensores de índices de refração de meios exteriores à fibra. Essa caracterização foi realizada usando diferentes amostras de fluidos tais como, álcool, gasolina, aguarrás, tíner, querosene e nafta. O maior deslocamento em comprimento de onda apresentado pela rede foi de 15,57 nm na presença do querosene. A sensibilidade média ao índice de refração da rede foi 2,6x10-6 pm-1 para a região compreendida entre 1,432 (tíner) e 1,448 (querosene). Esta sensibilidade resulta em uma mínima variação de índice de refração de 2,6x10-5 que pode ser medida por um analisador de espectros óticos com precisão em comprimento de onda de ± 5pm. O tempo de resposta do sensor foi da ordem de 3 segundos. As redes de Bragg foram caracterizadas como dispositivo sensor de temperatura dos fluidos. As redes de Bragg foram produzidas inicialmente em fibras SMF hidrogenadas e posteriormente em fibras fotossensíveis, utilizando a técnica de escrita interferométrica com máscara de fase e laser ultravioleta. Os dispositivos foram caracterizados como sensor de temperatura, tendo sido feito um estudo para estabilização térmica dos mesmos. A sensibilidade das redes variou desde 10,2 nm/ºC até 11,4 nm/ºC. A precisão deste tipo de sensor está intimamente relacionada com a largura de banda espectral da rede, portanto, um sistema de gravação utilizando a técnica de escrita com máscara de fase e laser UV foi implementado, tornando possível a escrita de redes mais longas com menor largura de banda.This work describes the production of fiber Bragg gratings and long period gratings in optical fibers and their characterization as sensors devices in the detection of hydrocarbons that flow in pipelines, as well as its temperature measurement. The work was accomplished at Laser Laboratory of UTFPR. The long period gratings were produced using the point-to-point electric arc discharge technique from a splice machine and characterized as refractive index sensors of the fiber surroundings. The characterization was accomplished using different samples of alcohol, gasoline, turpentine, thinner, kerosene and naphtha. The biggest wavelength shift presented by the grating was 15.57 nm in the presence of the kerosene. The average refractive index grating sensitivity was 2.6x10-6 pm-1 in the range from 1.432 (thinner) to 1.448 (kerosene). This sensitivity relates to a smallest refractive index variation of 2.6x10-5 that can be measured, for an optical spectrum analizer with wavelength precision of ± 5 pm. The response time of the sensor was 3 seconds for the different samples used. The fiber Bragg gratings were characterized as temperature sensor devices of the samples. The gratings were produced both in SMF hydrogenated and photosensitive fibers, using an ultraviolet laser and a phase mask interferometer. The devices were characterized as temperature sensors, and a study for thermal stabilization of them was carried out. The obtained sensor sensitivity ranged from 10.2 nm/ºC up to 11.4 nm/ºC. As the precision of this type of sensor is related to the bandwidth of the fiber Bragg grating, a writing system technique based on a phase mask and an UV laser was implemented, making possible the writing of long and narrow bandwidth gratings.
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Wei, Tao. "Fabrication of long-period fiber gratings by CO₂ laser irradiation for high temperature applications." Diss., Rolla, Mo. : Missouri University of Science and Technology, 2008. http://scholarsmine.mst.edu/thesis/pdf/Wei_09007dcc804a8ac2.pdf.
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Thesis (M.S.)--Missouri University of Science and Technology, 2008.Vita. The entire thesis text is included in file. Title from title screen of thesis/dissertation PDF file (viewed March 31, 2008) Includes bibliographical references (p. 33-36).
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Kinney, Stuart. "The development of an optical position sensor." Virtual Press, 1998. http://liblink.bsu.edu/uhtbin/catkey/1115421.
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A theoretical study of an electrically passive, loss-compensated, optical position sensor is the goal of this project. Optical fiber sensors exploit light as the information carrier. Fiber-optic sensors consist of a constant light source launched into an optical fiber and transmitted to another point at which a measurement is made.In the proposed optical position sensor, a Light Emitting Diode (LED) produces a constant beam of light, which is channeled through an optical fiber to a Graded Index (GRIN) lens. This lens makes all the light rays parallel to one another, a process called collimation. The light then enters a polarizer which is a lens that further orders the light rays in a process called polarization.Then the light enters a chamber in which a doubly refracting (birefringent) crystal is situated. The crystal is a wedge, and thus has a varying thickness throughout its length. The light beam strikes the crystal, sending a spectrum, or spectral signature, that is distinct to the particular thickness of the crystal. That signature goes directly from the chamber housing the crystal into a lens called an analyzer which orders the light again through polarization. Then the light goes into another GRIN lens, and this GRIN lens focuses the light onto an optical fiber, which transmits the particular spectral signature of this light to an optical spectrum analyzer (OSA). The OSA uses a Photodiode Array to accept the incoming light, a device that takes in light and redistributes it to a monitor for display by the user. Such a device is called a detector. The thickness of the crystal that the light travels through is determined by the crystal's position.If the crystal rests on a platform which is connected to an object whose position must always be monitored, then the crystal will move as the object moves. The different spectral signatures shown on a monitor reveal different thicknesses of the crystal, which reveal different positions of the monitored object. The object whose position is measured is the measurand.The selected crystal is quartz. It has a 12.5-mm length, a width of 10.8-mm at its thinnest end, and a taper angle to the thickest end of only 0.008 degrees, which corresponds to a 0.17-micron difference between the two. This angle is called the polishing angle of the quartz. The quartz itself is called the active cell. The Photodiode Array Detector receives the spectral signature from the optical fiber, and that signature is projected on an OSA, which is software built-in to the computer. A mathematical program is used to evaluate the signature, and the position of the measurand is thereby revealed. How accurate the measurement is can be revealed by use of a control device. If the quartz crystal is moved by a measuring device, such as a micrometer, the distance that the crystal moved may be measured by the micrometer, as well as by the OSA. By comparing the two, the accuracy of the spectrograph, and the position it reveals, can be known.Department of Physics and Astronomy
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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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Xu, Xingyuan. "Improving the performance of FBG sensing system." Access electronically, 2006. http://www.library.uow.edu.au/adt-NWU/public/adt-NWU20070110.144936/index.html.
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Silva, Muñoz Rodrigo. "Structural Health Monitoring Using Embedded Fiber Optic Strain Sensors." Fogler Library, University of Maine, 2008. http://www.library.umaine.edu/theses/pdf/SilvaMunozR2008.pdf.
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Nagarajan, Anjana. "Chemical sensing applications of fiber optics." Thesis, This resource online, 1994. http://scholar.lib.vt.edu/theses/available/etd-07102009-040555/.
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Kahn, Mohammed Tariq Ekeramodien. "Development of a non-monochromatic lightwave sensor for applications in smart structures research." Thesis, Peninsula Technikon, 1998. http://hdl.handle.net/20.500.11838/888.
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Thesis (MTech (Electrical Engineering))--Peninsula Technikon, Cape Town, 1998The purpose of this study was to perform an investigation into advances in the field of opto-electronics and to develop a suitable lightwave sensor, for application in smart structures research. Included in the scope of this research was the theoretical development and analysis of an appropriate technology to lead to an implementation of such sensors. This project forms part of an overall plan to gain experience in optoelectronic (photonic) sensor design. In research done previously in smart structure monitoring, piezo-electric techniques with the usual electrical interconnections was used. In a highly distributed sensor system the problems of electromagnetic interference, the tribo-electric effect and noise could be problematic. In this research, opto electronic techniques were thoroughly researched and an improvement on laser based fibre-optic interferometers was made. A non monochromatic lightwave interferometer was developed from theory and a prototype tested. The results suggests that an interferometric sensor can be operated with a non monochromatic source by using a second interferometer to modulate the frequency spectrum of the light before it is detected by a photodetector. Various test and measurement circuits for improved photodetector performance were evaluated, as well as a study of signal processing techniques that would be of use for an upgrade of the project where specific feature detection and analysis using the sensor is envisaged. A specification for a computer based data acquisition system was developed to do initial tests. The project should continue, with the sensor head being improved and all the necessary signal processing routines programmed into a Labview based data acquisition system.
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Kahn, Mohammed Tariq Ekeramodien. "Miniaturised dedicated application opto-electronic sensors in the evolution of smart systems." Thesis, Peninsula Technikon, 2002. http://hdl.handle.net/20.500.11838/1196.
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Thesis (DTech (Electrical Engineering))--Peninsula Technikon, Cape Town, 2002In the last decade, the South Amcan Electricity Supply Commission would have had their ability to serve an ever demanding public severely tested. With the dilemma of providing electricity supply through hazardous environmental conditions, and with prospects of supplying power even beyond South Afiican borders, the need for a comprehensive damage and power delivery assessment strategy becomes all the more relevant. The rapid growth being made in the evolution of so called "intelligent" structures, with inherent sensor, actuator and control mechanisms built in can have direct influence on a power distribution network. At least in the foreseeable future, the impact ofphotonic sensors with inherent miniaturization, a foremost candidate in Smart System technology, can play a vital role in damage assessment of a potentially large network such as that found in the supply ofelectricity. Smart systems are nonliving systems that integrate the functions of sensing, actuation, logic and control, to respond adaptively to changes in their condition or environment to which they are exposed, in a useful and usually repetitive manner. Sensors are a fundamental part of the evolution of such systems and form the basis for the topic of this dissertation. The use ofoptical fiber sensors is increasing widely mainly due to their (a) miniature size, (b) remote signal processing ability, and (c) multiplexing capabilities. Because of the above features a variety of optical fiber sensing techniques has evolved over the years having potential for a myriad of applications. In this work a systems model and equations was developed for modeling the propagation of light in a optical waveguide, in order to study a Fabry Perrot sensor topology for application as a miniaturised sensor in a new type of smart structure, namely a smart electrical power system.
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Miller, Mark S. "Advances in elliptical-core two-mode optical fiber sensors." Thesis, Virginia Tech, 1990. http://hdl.handle.net/10919/41617.
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Methods designed to improve the practicality of the elliptical-core two-mode optical fiber sensors for use in real-life applications are presented. The improvements include the development of insensitive lead fibers and an optical device which allows fringe counting at the output of the sensor. The insensitive leads eliminate extraneous perturbations and effectively isolate the sensing region. The fringe counting optics are designed to generate quadrature-phase shifted signals, thereby allowing the determination of whether the strain is increasing or decreasing.
Work performed to advance the understanding of the effect of sensor placement within a composite specimen is also presented. Optical fiber sensors are embedded between different laminae of a graphite-epoxy composite panel, and the outputs of the sensors are shown to be proportional to the distance of the sensor from the neutral axis.Master of Science
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Ferreira, Ricardo Xavier da Graça. "Acoustic optical modulation in optical fibre for sensing applications." Master's thesis, Universidade de Aveiro, 2013. http://hdl.handle.net/10773/11646.
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Mestrado em Engenharia FísicaO presente trabalho teve como objetivo desenvolver um sensor de fibra óptica intrínseco para viscosidade com base no efeito acústoótico aplicado em redes de Bragg. Foram utilizadas fibras de silica e poliméricas para medições com baseadas no espectro e no tempo de resposta da rede quanto sujeitas ao efeito acústo-ótico. O resultado é um viscosímetro multi-paramétrico com um distinto potencial futuro. Com base no conhecimento adquirido, é proposto um novo design e mecanismo de detecção.
The present work aimed to develop an intrinsic optical fibre sensor for viscosity based on the acousto-optic effect applied into fibre Bragg grating. Polymer and silica optical fibres were employed for measurements based on the spectra and the grating response times when subjected to the acousto-optic effect. The results is a multi-parameter viscometer with a distinctive future potential. Based on the knowledge acquired, a new design and sensing mechanism is advanced.
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Possetti, Gustavo Rafael Collere. "Sensores em fibra ótica para avaliação de combustíveis líquidos." Universidade Tecnológica Federal do Paraná, 2013. http://repositorio.utfpr.edu.br/jspui/handle/1/514.
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CAPES, CNPq), Fundação Araucária, Agência Nacional do Petróleo (ANP), FINEPNeste trabalho é apresentado um estudo sobre a aplicabilidade de sensores em fibra ótica baseados em redes de período longo como ferramentas para avaliar combustíveis líquidos. O estudo pautou-se em investigação experimental e no levantamento das principais características metrológicas dos sensores, incluindo a estimativa de incertezas segundo diretrizes recomendadas por organizações internacionais de padronização. Nesse sentido, investigou-se o desempenho dos sensores na determinação do teor de etanol presente em misturas etanol-gasolina. Os resultados obtidos mostraram que concentrações de etanol foram mensuradas nessas misturas com resolução de até 0,14% v/v. Adicionalmente, avaliaram-se os comportamentos dos sensores na identificação do teor de etanol em misturas etanol-água e propuseram-se dois métodos para que tais determinações fossem unívocas para toda a faixa de concentração de etanol. Nessa aplicação foi possível medir concentrações de etanol com resolução de até 0,17% v/v. Os sensores foram ainda empregados nas avaliações de biodiesel, de óleo de origem e de óleo diesel presentes em misturas binárias e homogêneas. Para tanto, três métodos foram desenvolvidos com o intuito de superar as limitações impostas pelos elevados índices de refração dessas substâncias, possibilitando quantificações sem demandar segregação de componentes ou fibras óticas especiais. Dessa maneira, viabilizou-se a identificação de teores de biodiesel em misturas biodiesel-óleo diesel com resolução de até 0,05% v/v. Por fim, implementou-se um método de interrogação de redes de período longo a partir da leitura de sinais de reflexão disponibilizados por uma rede de Bragg, o qual foi utilizado para avaliar misturas contendo óleo de origem e biodiesel. Nesse caso, as determinações dos teores de óleo foram realizadas com resolução de 0,10% v/v.
This work shows a study about the applicability of optical fiber sensors based on long period gratings as tools for assessment of liquid fuels. The study was based on both experimental research and evaluation of the main metrological characteristics of the sensors, including the estimative of uncertainties according to guidelines recommended by international organizations for standardization. In a sense, it was evaluated the performance of sensors for determining the ethanol concentration in ethanol-gasoline blends. The results obtained showed that ethanol concentrations were measured in these mixtures with resolution up to 0.14% v/v. The use of the sensors to measure ethanol in ethanol-water blends was also investigated and two methods were proposed to establish the ethanol content without ambiguity for the whole ethanol concentration range. In this application it was possible to measure ethanol concentrations with resolution up to 0.17% v/v. Optical fiber sensors were also employed for evaluating biodiesel, vegetable oil and petrodiesel concentrations in binary and homogeneous mixtures. Three methods were developed in order to overcome the drawbacks imposed by the high refractive indices of these substances, allowing quantifications without requiring segregation of components or specialty optical fibers. Biodiesel concentrations could be identified in biodiesel-petrodiesel blends with resolution up to 0.05% v/v. Finally, an alternative method to interrogate long period gratings that employs the reflection provided by a fiber Bragg grating was implemented to evaluate mixtures of vegetable oil and biodiesel. In this case, oil concentrations were determined with resolution of 0.10% v/v.
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Shih, Jessica Chu-Huei. "Concentric-core optical fiber sensors." Thesis, Virginia Polytechnic Institute and State University, 1986. http://hdl.handle.net/10919/91069.
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This thesis describes the implementation of a mechanical strain sensor which uses concentric core optical fiber waveguide as the sensing element. When this particular type of fiber is strained, a transfer of optical power occurs between propagating modes in the two concentric cylindrical cores of the fiber. This strain-induced redistribution of optical power may be detected at the output end of the fiber using either two separated optical detectors or a two dimensional detector array. The calibrated strain sensitivity of the sensor is reported and suggestions for continuing research are discussed.M.S.
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Dreyer, Uilian José. "Sensor a fibra óptica para monitoração de mancais de hidrogeradores." Universidade Tecnológica Federal do Paraná, 2014. http://repositorio.utfpr.edu.br/jspui/handle/1/922.
Full textAbstract:
CAPESEste trabalho tem como objetivo desenvolver um sensor a fibra óptica para a monitoração de temperatura em mancais de hidrogeradores de usinas hidrelétricas. Foi apresentado o projeto gráfico, modelagem térmica, processo de montagem e testes realizados. Por tratar-se de uma inovação, é difícil a comparação com outros sensores ópticos desenvolvidos especificamente para monitorar temperatura em mancais de hidro geradores. Inicialmente, foram realizados ensaios preliminares com um protótipo para determinação da dinâmica térmica no interior dos mancais em situações diversas de operação. A partir dessa medição, foi idealizado um sensor óptico que possui duas fibras ópticas, com 3 redes de Bragg gravadas em cada uma delas. Essas redes são encapsuladas por uma haste de alumina coberta com anéis de material com elevada condutividade térmica onde as redes de Bragg se localizam, e baixa condutividade térmica no restante da haste. O procedimento, para calibrar as redes de Bragg do sensor, consistiu em varias a temperatura em degraus de 10°C desde 10°C até 80°C. Cada valor de temperatura permaneceu estável durante 20min, permitindo que o comprimento de onda refletido de cada sensor pudesse ser estimado mediante um histograma. A partir da calibração foram determinados os coeficientes de correlação e o coeficiente de sensibilidade térmica de cada sensor, bem como a incerteza padrão combinada dos mesmos. As incertezas foram divididas em dois tipos, A e B. As incertezas do tipo A, são relativas à dispersão amostral e são determinadas a partir da média, variância e desvio padrão das amostras realizadas durante a calibração. As incertezas do tipo B são obtidas de manuais e certificados de calibração. Foram realizados testes em laboratório com o objetivo de submeter o novo sensor a grandes variações térmicas, entre 15°C e 75°C e checar se as incertezas determinadas correspondiam na prática. Os resultados obtidos apresentam erro máximo de aproximadamente 0,9°C entre o sensor óptico e o sensor de referência PT100. Esse resultado situa-se dentro da faixa de valores de incerteza calculada para os sensores da fibra óptica 1, respectivamente 1,7°C, 1°C e 0,7°C para os sensores 1, 2 e 3. Assim como para a fibra 2, foram observados os valores de incerteza de 0,98°C e 0,71°C respectivamente para as FBG 1, 2 e 3. O desenvolvimento deste sensor possibilita a criação de novos sistemas de monitoração de temperatura ópticos aplicáveis em geradores de grande porte, bem coma interligação destes sistemas visando no futuro o mapeamento térmico total de um gerador utilizando sensoriamento óptico.
This work aims to develop a fiber optic probe for temperature monitoring in bearings of generators hydro power plants. Graphic design, thermal modeling, assembly and testing process is presented. Once it is innovation, it is difficult to compare with other optical transducers developed specifically for monitoring temperature in bearing hydro generators. Initially experiments were performed with a prototype for determination of the thermal dynamics inside the bearings in various operating situations. From this measurement, an optical transducer was designed which was two optical fibers with 3 Bragg gratings recorded in each of them. These gratings are encapsulated by a rod made of alumina and covered with rings of material with good thermal conductivity where the Bragg grating is located, and low thermal conductivity in the remainder of the rod. The procedure for calibrating the Bragg gratings of the transducer consisted of steps of 10°C in the temperature range from 10°C to 80°C. Each temperature value remained stable during 20 min, allowing the mean wavelength reflected from each sensor might be estimated by a histogram. Were determined from the calibration the correlation coefficient and the coefficient of thermal sensitivity of each sensor, and the combined standard uncertainty thereof. The uncertainties were divided into two types: Type A uncertainties are related to the sample dispersion and are determined from the mean, variance and standard deviation of the samples taken during calibration, and type B where uncertainties are obtained from manuals and certificates of calibration. Tests were conducted in laboratory with the aim to submit the new transducer to large temperature variations, ranging between 15°C and 75°C and to check if the uncertainties corresponded in practice. The results presented the maximum error of about 0.9°C between the optical sensor and the reference sensor PT100. This result is within the range of uncertainty values calculated for the fiber optical fiber 2, uncertainty values of 0.98°C, 0.85°C to 0.71°C respectively for the FBG 1, 2 and 3 were observed. The development of this transducer enables the creation of new systems for monitoring temperature optical applicable in generators, as well as the interconnection of these systems to the future the total thermal mapping of a generator using optical sensing.
5000
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Sualehe, Ivenso da Silva Vasco. "Produção e caracterização de redes de Bragg no visível gravadas por pulsos de femtossegundos em 248 nm." Universidade Tecnológica Federal do Paraná, 2016. http://repositorio.utfpr.edu.br/jspui/handle/1/2037.
Full textAbstract:
Este trabalho apresenta a gravação e caracterização de redes de Bragg em fibras óticas (FBGs), com comprimentos de onda otimizados para a banda do visível, a partir de pulsos de laser femtossegundo em UV ajustados por um oscilador paramétrico ótico (OPO – optical parametric oscillator). Para tal propósito foi usado o método de inscrição direta sob máscara de fase, tendo como base diferentes fibras óticas previamente hidrogenadas com vista a incrementar a sua fotossensibilidade. Durante o processo de gravação dos sensores a fibra ótica, as FBGs foram monitoradas espectralmente em reflexão e posteriormente caracterizados em temperatura e deformação longitudinal, para a análise dos seus coeficientes de sensibilidades; seus principais parâmetros pós-gravação foram analisados comparativamente em relação às redes de Bragg funcionais na faixa espectral do infravermelho.In this work, a visible wavelength fiber Bragg gratings (FBGs) were produced using ultrafast laser pulses adjusted with an OPO (optical parametric oscillator) to 248 nm UV femtosecond laser source. For that purpose it was employed the normal phase-mask method and different fibers loaded with hydrogen previously, in order to increase its photosensitivity. During de process the spectral characteristics were analyzed in terms of reflection as well as temperature and longitudinal deformations were made to analyze the post inscription main parameters of sensitivity comparing with IR spectral range produced FBGs.
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Flinn, A. R. "Optical fibres in pre-detector signal processing." Thesis, University of St Andrews, 1989. http://hdl.handle.net/10023/13599.
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The basic form of conventional electro-optic sensors is described. The main drawback of these sensors is their inability to deal with the background radiation which usually accompanies the signal. This 'clutter' limits the sensors performance long before other noise such as 'shot' noise. Pre-detector signal processing using the complex amplitude of the light is introduced as a means to discriminate between the signal and 'clutter'. Further improvements to predetector signal processors can be made by the inclusion of optical fibres allowing radiation to be used with greater efficiency and enabling certain signal processing tasks to be carried out with an ease unequalled by any other method. The theory of optical waveguides and their application in sensors, interferometers, and signal processors is reviewed. Geometrical aspects of the formation of linear and circular interference fringes are described along with temporal and spatial coherence theory and their relationship to Michelson's visibility function. The requirements for efficient coupling of a source into singlemode and multimode fibres are given. We describe interference experiments between beams of light emitted from a few metres of two or more, singlemode or multimode, optical fibres. Fresnel's equation is used to obtain expressions for Fresnel and Fraunhofer diffraction patterns which enable electro-optic (E-0) sensors to be analysed by Fourier optics. Image formation is considered when the aperture plane of an E-0 sensor is illuminated with partially coherent light. This allows sensors to be designed using optical transfer functions which are sensitive to the spatial coherence of the illuminating light. Spatial coherence sensors which use gratings as aperture plane reticles are discussed. By using fibre arrays, spatial coherence processing enables E-0 sensors to discriminate between a spatially coherent source and an incoherent background. The sensors enable the position and wavelength of the source to be determined. Experiments are described which use optical fibre arrays as masks for correlation with spatial distributions of light in image planes of E-0 sensors. Correlations between laser light from different points in a scene is investigated by interfering the light emitted from an array of fibres, placed in the image plane of a sensor, with each other. Temporal signal processing experiments show that the visibility of interference fringes gives information about path differences in a scene or through an optical system. Most E-0 sensors employ wavelength filtering of the detected radiation to improve their discrimination and this is shown to be less selective than temporal coherence filtering which is sensitive to spectral bandwidth. Experiments using fibre interferometers to discriminate between red and blue laser light by their bandwidths are described. In most cases the path difference need only be a few tens of centimetres. We consider spatial and temporal coherence in fibres. We show that high visibility interference fringes can be produced by red and blue laser light transmitted through over 100 metres of singlemode or multimode fibre. The effect of detector size, relative to speckle size, is considered for fringes produced by multimode fibres. The effect of dispersion on the coherence of the light emitted from fibres is considered in terms of correlation and interference between modes. We describe experiments using a spatial light modulator called SIGHT-MOD. The device is used in various systems as a fibre optic switch and as a programmable aperture plane reticle. The contrast of the device is measured using red and green, HeNe, sources. Fourier transform images of patterns on the SIGHT-MOD are obtained and used to demonstrate the geometrical manipulation of images using 2D fibre arrays. Correlation of Fourier transform images of the SIGHT-MOD with 2D fibre arrays is demonstrated.
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Cameron, Alexander John. "A Bayesian approach to optimal sensor placement." Thesis, University of Oxford, 1989. http://ora.ox.ac.uk/objects/uuid:ad201132-d418-4ee4-a9d5-3d79bd4876a7.
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By "intelligently" locating a sensor with respect to its environment it is possible to minimize the number of sensing operations required to perform many tasks. This is particularly important for sensing media which provide only "sparse" data, such as tactile sensors and sonar. In this thesis, a system is described which uses the principles of statistical decision theory to determine the optimal sensing locations to perform recognition and localization operations. The system uses a Bayesian approach to utilize any prior object information (including object models or previously-acquired sensory data) in choosing the sensing locations.
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Ferguson, Jane A. "Fiber optic chemical sensors : the evolution of high-density fiber-optic DNA microarrays /." Thesis, Connect to Dissertations & Theses @ Tufts University, 2001.
Find full textAbstract:
Thesis (Ph.D.)--Tufts University, 2001.Adviser: David R. Walt. Submitted to the Dept. of Chemistry, Includes bibliographical references (leaves 197-208). Access restricted to members of the Tufts University community. Also available via the World Wide Web;
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Kawano, Marianne Sumie. "Transdutor a fibra ótica para análise de biodiesel." Universidade Tecnológica Federal do Paraná, 2010. http://repositorio.utfpr.edu.br/jspui/handle/1/1344.
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CNPQ; Fundação Araucária; PETROBRÁSNeste trabalho é apresentado um estudo sobre a aplicabilidade de redes de período longo e estruturas de redes de período longo, gravadas em fibra ótica de sílica, quando empregadas como transdutores de índice de refração para avaliar biodiesel e os óleos de origem desses biocombustíveis. Como amostras, foram utilizados óleos de soja, de fritura e de girassol, biodiesel de óleo de soja e biodiesel de óleo de girassol. Os experimentos foram realizados utilizando uma rede de período longo convencional e uma estrutura de rede de período longo, chamada de rede de período longo em cascata, na qual uma rede período longo é empregada numa configuração interferométrica similar a um interferômetro de Michelson. Inicialmente, foram analisadas as diversas amostras de óleo e biodiesel em temperatura ambiente. Os resultados mostraram que quando os dispositivos são imersos nas diferentes amostras, que possuem índice de refração igual ou maior do que o da casca da fibra ótica, as condições de guiamento da luz não permitem mais que estes possam ser usados como transdutores de índice de refração. Entretanto, no caso da rede de período longo em cascata, quando somente a cavidade do interferômetro de Michelson, ou parte desta cavidade, é colocada em contato com as amostras, o dispositivo se mostra uma promissora ferramenta para verificação da qualidade do biodiesel. Ainda na tentativa de melhorar o desempenho da rede de período longo em cascata, as amostras foram aquecidas com o objetivo de alterar o seu índice de refração, tornando-o menor do que o índice de refração da casca da fibra. Os resultados mostraram que o aumento sistemático da temperatura da amostra constitui um eficiente artifício para análise de substância cujos índices de refração, à temperatura ambiente, são iguais ou maiores que o da casca da fibra ótica.
This work presents a study of the applicability of long period gratings and long period gratings structures, written in silica optical fiber, when they are employed as a transducer of refractive index to analyze the biodiesel and their original oils. As samples were used: soybean oil, fried oil, sunflower oil, soybean oil biodiesel and biodiesel from sunflower oil. The experiments were performed using a conventional long period grating and a long period grating structure named as cascaded long period grating, in which a long period grating is employed on an interferometric configuration similar to a Michelson interferometer. Initially, were analyzed several samples of oil and biodiesel at room temperature. The results showed that when the devices were immersed in the different samples, which have refractive index equal or higher than that of the optical fiber cladding, the guiding light conditions no longer allow these devices for the use as a refractive index transducer. However, if the cascaded long period grating is used, when only the cavity of the Michelson interferometer or part of this cavity is placed in contact with samples, the devide shows a promising tool for checking the quality of biodiesel. Still trying to improve the performance of the cascade long period gratings, the samples were heated in order to modify their refractive index, making them smaller than the refractive index of the fiber cladding. The results showed that the systematic increase of the sample temperature is an efficient artifice for analysis of substances which refractive index, at room temperature, are equal of higher than that of the optical fiber cladding.
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Peterson, Brian James. "Wireless sensor interrogator design for passive, resonant frequency sensors using frequency modulation spectroscopy." Thesis, Montana State University, 2009. http://etd.lib.montana.edu/etd/2009/peterson/PetersonB0509.pdf.
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The lack of passive, wireless, chemical and biological sensor systems is a significant impediment to sensor system applications. While active sensors with a wireless communications link continue to decrease in power consumption, they still require a power source, such as a battery. This active power consumption limits the useful life of the sensor and its applications. A more attractive solution would be a passive, wireless, chemical and biological sensor integrated with a wireless interrogation platform to monitor the sensor. The focus of this thesis is the realization of a wireless sensor interrogator capable of monitoring multiple, passive, resonant-frequency sensors. It is demonstrated, using Frequency Modulation Spectroscopy techniques, that the resonant frequency of a passive sensor can be detected and tracked over time. Simulated results are presented that verify the functionality of the proposed wireless sensor interrogator. In addition, an experimental hardware setup and subsequent experimental results are presented that verify the simulation results. Considerations for the design of the wireless sensor interrogator and opportunities for future research are discussed.
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Michael, Karri L. "Development of high-density optical fiber arrays : new designs and applications in microscopy, microfabrication and chemical sensing /." Thesis, Connect to Dissertations & Theses @ Tufts University, 1999.
Find full textAbstract:
Thesis (Ph.D.)--Tufts University, 1999.Adviser: David R. Walt. Submitted to the Dept. of Chemistry. Includes bibliographical references (leaves 233-253). Access restricted to members of the Tufts University community. Also available via the World Wide Web;
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Hamner, Vincent N. "A fiber optic polarimeter for use in chemical analysis." Thesis, Virginia Tech, 1990. http://hdl.handle.net/10919/42892.
Full textAbstract:
Polarimetry, as applied to chemical analysis, deals with the
determination of the extent and direction that an optically
active chemical species will rotate incident linearly
polarized light. Although well developed for physical
sensing, the technique of fiber optic polarimetry for
chemical sensing remains in its infancy. This thesis is
concerned with the design and development of an optical fiber
polarimeter which measures the optical rotation of linearly
polarized light that occurs in a sensing region between two
multi-mode optical fibers. Over short distances, the
polarization preserving capabilities of large-core multi-mode
optical fibers were investigated. Polarimetric analyses were
performed using sucrose and quinine hydrochloride. The
instrument has a resolution of O.O8·, and is an excellent
platform for an LC or FIA detector. Its more intriguing
future lies in evanescent field sensor applications and
studies of chiroptical surface interactions.
Master of Science
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Murphy, Kent A. "Novel phase-modulated optical fiber sensors." Diss., Virginia Tech, 1992. http://hdl.handle.net/10919/39712.
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Patyk, Rodolfo Luiz. "Instrumentação baseada em redes de Bragg em fibra ótica para a monitoração da vazão de fluídos através do uso da termometria." Universidade Tecnológica Federal do Paraná, 2010. http://repositorio.utfpr.edu.br/jspui/handle/1/1342.
Full textAbstract:
Neste trabalho foi inferida a vazão de um fluido que escoava em um tubo de cobre através do uso da termometria em diferentes regimes de escoamento, com o uso de sensores óticos de temperatura baseados em redes de Bragg escritas em fibras óticas (FBG). Foi utilizado um processo de medição não-intrusivo de vazão através do uso da termometria o qual consiste no monitoramento da temperatura em dois pontos fixos, com uma distância conhecida (d), na parede externa do tubo. Além dos sensores óticos de temperatura foram utilizados sensores comerciais de temperatura, termopares, com a intenção de comparar os resultados obtidos experimentalmente. No experimento o fluido estará escoando com uma temperatura T1, e em determinado tempo será liberado um pequeno volume de fluido com temperatura T2, onde T2 > T1, simulando um pulso térmico. É monitorada a evolução temporal do pulso térmico e anotado o tempo de trânsito (t) entre os dois sensores de temperatura. Com o valor da distância (d) e o tempo de trânsito (t) obtemos a velocidade média de escoamento (v). De posse da (v) e área de seção transversal do tubo (A) podemos inferir a vazão. A técnica de medição não-intrusiva de vazão através do uso da termometria foi testada para diferentes regimes de escoamento: laminar, transição e turbulento. Foram comparados os valores medidos da vazão mássica do sistema com os valores obtidos experimentalmente para os sensores comerciais e redes de Bragg. Para o regime turbulento a exatidão de medição da velocidade de escoamento do fluido foi de 0,75 para os sensores óticos e 0,60 para os sensores comerciais. No caso do regime de transição a exatidão na medida foi de 0,90 para o sensor ótico e 0,69 para os sensores comerciais. Finalmente para o regime laminar a exatidão nas medidas foram [sic] de 0,98 para os sensores ótico [sic] e 0,76 para os sensores comerciais.In this work we inferred a fluid flow seeping from a cooper pipe through thermometers scheme in different flows, through the use of optical sensors based on temperature Bragg Gratings written in optical fiber (FBG). We used a non-intruse measurement process through the use of thermometry, which consists of monitoring the temperature at two fixed points with a know distance (d) on the outer wall of the tube. Besides the optical sensors of temperature, sensors were used for commercial temperature, thermocouples, with the objective of comparing the results obtained experimentally. In the experiment, the fluid is flowing at a temperature T1, and will be released at any given time a small volume of fluid with temperature T2, were T2 > T1, simulating a thermal pulse. It's monitored the evolution of the thermal pulse and noted the transit time (t) between the two temperature sensors. With the value of distance (d) and transit time (t) we obtain the average velocity of flow (v). Tenure velocity (v) and the tube transversal sectional area (A) we can infer the non-intrusive measurement technique flow. The flow though the use of thermometry was tested for different flow regimes: laminar, transitional and turbulent. We compared the values measured with the mass flow of the system with the experimental values for the sensors and commercial FBG's. In the turbulent the accuracy of measuring the speed and fluid flow was 0.75 to 0.60 optical sensors and sensor for commercial purposes. Finally for the laminar accuracy in the measurements were 0.98 optical sensors and 0.76 for commercial sensors.
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Beadle, Brad Michael. "Fiber optic sensor for ultrasound." Thesis, Georgia Institute of Technology, 1999. http://hdl.handle.net/1853/19173.
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Bolton, Jason C. "Spectroscopic Analysis of Hemolymph and Hemocyanin for the Development of a Non-Invasive Lobster Vitality Sensor." Fogler Library, University of Maine, 2008. http://www.library.umaine.edu/theses/pdf/BoltonJC2008.pdf.
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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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Milczewski, Maura Scandelari. "Avaliação das forças ortodônticas utilizando sensores de fibra ótica." Universidade Tecnológica Federal do Paraná, 2008. http://repositorio.utfpr.edu.br/jspui/handle/1/131.
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Este estudo desenvolve uma técnica para avaliar a magnitude das forças aplicadas sobre um dente por meio da aparelhagem ortodôntica utilizando sensores de fibra ótica com redes de Bragg (FBG) e fibras óticas poliméricas. Esses sensores apresentam características como pequena dimensão, flexibilidade e servem como transdutores óticos, convertendo deformação mecânica em deslocamento espectral, ou em intensidade luminosa, demonstrando ser adequados para inspeção com precisão. Os ensaios foram realizados sobre um modelo maxilar elastomérico que simula uma fase de um tratamento ortodôntico. Os sensores foram posicionados entre o acessório ortodôntico e o dente. Como resultado observou-se valores de forças variando de 0,10 a 0,63 N sobre a superfície do dente incisivo central, medidas com FBG e um intervalo de 0,18 até 0,45 N quando aferidas com fibras poliméricas. O estudo viabiliza a construção futura de sensores para serem empregados em estudos in vivo.Fibre Bragg gratings and polymer optical fibre sensors we used to investigate orthodontic forces. These sensors offer advantages for their use due to the reduced dimensions, chemical inertness, dielectric structure, high sensitivity and compatibility. The measured signal is the wavelength position of the peak in theoptical reflection spectra of the Bragg sensor or changes in the intensity of the transmitted light in polymer fibre sensors, which are related to the transversal force applied on the tooth. The technique is tested in an artificial maxilla model, witch reproduces the orthodontic structure with the sensor placed between the metal tooth and the bracket. The results show forces intensity from 0,10 to 0,63 N over the central incisor when FBGs is used and from 0,18 to 0,45 N using a polymer fibre. The sensor can detect the dissipated forces in the orthodontic model. New fibre optic materials can offer promising improvement in the study of orthodontics forces, in vivo.
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Shute, Marcus William Sr. "Polarization-maintaining optical fiber as a sensor of shell vibrations." Diss., Georgia Institute of Technology, 1994. http://hdl.handle.net/1853/17915.
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Bortolotti, Fernando. "Estudo térmico da excitatriz estática do gerador da usina hidrelétrica derivação do Rio Jordão usando sensores a fibra ótica." Universidade Tecnológica Federal do Paraná, 2013. http://repositorio.utfpr.edu.br/jspui/handle/1/870.
Full textAbstract:
Este trabalho tem como objetivo compreender o comportamento térmico da excitatriz
estática da Usina Hidrelétrica Derivação do Rio Jordão (UHEDRJ), empregando redes de
Bragg em fibra ótica como sensor de temperatura. São apresentados os componentes da excitatriz estática, com foco na ponte retificadora trifásica controlada a tiristores. Com a calibração pôde-se conhecer os erros e incertezas dos sensores, tendo as maiores contribuições de incerteza devidas à dispersão das amostras e ajuste das curvas pelo método dos mínimos quadrados.
A instrumentação da excitatriz estática permite que sejam realizados ensaios em
diversas condições de operação da unidade geradora: partida da unidade, excitação a vazio, ou seja, com o gerador energizado, mas sem estar conectado ao sistema elétrico; excitada e sincronizada, ou seja, gerador energizado e sincronizado com o sistema elétrico; rampa de carga até a carga nominal e parada da unidade. Os ensaios realizados permitem estimar o comportamento térmico da ponte retificadora, variações de temperatura de cada tiristor no painel e como ocorrem as
dissipações térmicas.This work aims to study the static exciter thermal behavior of the hydroelectric power plant Rio Jordão (UHEDRJ) using fiber Bragg gratings as temperature sensor. The components of the static exciter are presented, with a focus on three-phase thyristor controlled bridge rectifier. The calibration allows knowing the errors and uncertainties of the sensors and the greatest uncertainty contributions due to dispersion of the samples and adjusting the curves by the method of minimun squares. The static exciter instrumentation allows performed the tests in various operating conditions of the generating unit: starting unit, excitation empty (with the generator energized but not connected to the grid); excited and synchronized (energized and synchronized with the power grid), ramp load to rated load and the unit stopped. The tests allow to estimate the thermal behavior of the bridge rectifier, temperature variations of each thyristor in the panel and how occur the thermal dissipation.
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Nau, Gregory Merrill. "Optical fiber detection of ultrasonic vibration and acoustic emission." Thesis, This resource online, 1992. http://scholar.lib.vt.edu/theses/available/etd-09292009-020053/.
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K, C. Ravikumar. "Spread spectrum techniques for distributed multimeasurand optical fiber sensors /." This resource online, 1993. http://scholar.lib.vt.edu/theses/available/etd-03142009-040658/.
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Fernandes, Alecio Pontes. "Implementação de uma nova tecnica para demodulação digital de sinal de giroscopio a fibra optica." [s.n.], 2009. http://repositorio.unicamp.br/jspui/handle/REPOSIP/259572.
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Orientador: Elnatan Chagas FerreiraDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Elétrica e de Computação
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Resumo: Giroscópios são dispositivos usados para medir rotação angular, sendo extensivamente empregados em sistemas de guiamento, navegação e estabilização. Entre os diversos tipos de giroscópios, o IFOG (Giroscópio Interferométrico a Fibra Óptica) baseado no efeito de Sagnac é uma das soluções mais interessante, dada sua alta sensibilidade, resolução, ausência de partes móveis, confiabilidade, tamanho compacto e imunidade a interferências eletromagnéticas. Este trabalho descreve a implementação de um circuito digital de demodulação para IFOGs operando em malha aberta utilizando a técnica de zero-crossing (cruzamento em zero). A técnica implementada no circuito eletrônico descrito neste trabalho emprega um clock quase-síncrono para processamento, o que leva a um esquema de demodulação digital preciso, simples e de baixo custo. O circuito de demodulação proposto foi testado em laboratório, utilizando um sinal de giroscópio emulado. Os resultados experimentais medidos no protótipo mostraram que a resolução final do circuito de detecção é 1000 vezes melhor que a resolução possível de se alcançar em um demodulador zero-crossing digital convencional com clock síncrono
Abstract: Gyroscopes are devices used to measure angular orientation, being extensively employed for guidance, navigation and stabilization. Among the many types of gyroscopes, IFOG (Interferometer Fiber Optic Gyroscope), based on Sagnac effect, is the most interesting solution due to its high sensitivity, resolution, reliability, small size and EMI immunity. The present work describes a digital electronic circuit implementation for open-loop IFOGs using zero-crossing demodulation techniques. The technique used in the electronic circuit described in this work employs a quasi-synchronous clock for signal processing which leads to an accurate, simple and low cost digital demodulation scheme. The experimental results of the prototype showed that the final detection resolution is 1000 times better than one achieved by the conventional synchronous clock zero-crossing digital demodulator
Mestrado
Eletrônica, Microeletrônica e Optoeletrônica
Mestre em Engenharia Elétrica
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Heidemann, Bárbara Rutyna. "Transdutor a fibra ótica para análise de biodiesel e misturas BX." Universidade Tecnológica Federal do Paraná, 2011. http://repositorio.utfpr.edu.br/jspui/handle/1/403.
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CNPqUma alternativa para as análises tradicionais do biodiesel e misturas BX, como a cromatografia, a espectroscopia e a ressonância magnética nuclear, é a análise por meio de um transdutor de índice de refração a fibra ótica, como uma LPG. Entretanto, como os índices de refração do biodiesel e do óleo diesel são próximos ou maiores do que o índice de refração da casca da fibra na qual a rede se encontra, há uma grande perda de energia para o meio externo, comprometendo a eficiência do sensor. Com o propósito de diminuir o índice de refração do biodiesel, uma substância miscível e de baixo índice de refração, o ciclohexano, foi escolhida para ser misturada a esse biocombustível, assim como à mistura óleo diesel-biodiesel. Os resultados obtidos mostram que o ciclohexano não é reagente com essas substâncias, atuando apenas como solvente. Além disso, as diluições 1:1 e 1:2 (uma parte de mistura BX para uma parte de ciclohexano; uma parte de mistura BX para duas partes de ciclohexano) têm índices de refração menores do que o da casca da fibra, o que faz com que a banda ressonante seja deslocada para menores comprimentos de onda, possibilitando, assim, a detecção por meio da LPG. Após as curvas de calibração serem representadas em gráficos de variação de comprimento de onda (nm) em função da concentração de biodiesel em óleo diesel, BX (% v/v), para as duas diluições, obteve-se, por meio da derivada desta, a sensibilidade. As características metrológicas foram calculadas, levando à obtenção da incerteza expandida, que é de 3,7 % para a diluição 1:1 e de 5,9 % para a diluição 1:2, para um nível de confiança de 95,45 %.
An alternative for the traditional biodiesel and BX blends analysis (X is the biodiesel volumetric concentration in the blend), such as chromatography, spectroscopy and nuclear magnetic resonance, is by means of an optical fiber refractive index transducer, such as an LPG. However, as the biodiesel and diesel refractive index are close or bigger than the fiber cladding index, there is an important loss of power to the surrounding environment, impairing the sensor performance. In order to decrease the refractive index of biodiesel, a miscible and low refractive index substance, cyclohexane, was chosen to blend to this biofuel and also to the biodiesel-diesel blend. The results show that the cyclohexane does not react with biodiesel, acting only as a solvent. Besides, the 1:1 and 1:2 dilution (one part of BX blend and one part of cyclohexane in volume concentration; one part of BX blend and two parts of cyclohexane in volume concentration) have a refractive index lower than the fiber cladding, what shifts the resonant band of the LPG towards lower wavelengths. After representing the calibration curves in graphics of wavelength shift (nm) as function of biodiesel-diesel blend concentration, BX (% v/v), for both dilution, the concentration sensitivity has been obtained. The metrological characteristics were calculated, leading to the expanded uncertainty, which is 3,7 % for the 1:1 dilution and 5,9 % for the 1:2 dilution, for a 95,45 % confidence level.
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Poland, Stephan H. "Applications of optical fiber sensors with thick metal coatings." Thesis, This resource online, 1994. http://scholar.lib.vt.edu/theses/available/etd-06232009-063456/.
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Xu, Lina. "Optical fiber humidity sensor based on evanescent wave scattering." MSSTATE, 2004. http://sun.library.msstate.edu/ETD-db/theses/available/etd-07092004-112625/.
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An optical fiber humidity sensor has been devised using a porous sol-gel silica (PSGS) coating as a transducer. Evanescent wave scattering (EWS) in the PSGS coating. PSGS particles are highly hydrophilic and have a strong tendency to absorb water molecules from the surrounding environment. The absorbed water molecules form a thin layer on the inner surface of the pores inside the porous silica and enhance EWS, from which an indicatory signal can be obtained. The humidity sensor presented in this thesis has a fast response, is reversible, low cost, and has a broad dynamic relative humidity range from 3.6?0-6% to 100% or humidity range from 1.2ppm to 30000ppm. Because of its multiple advantages, including immunity to electromagnetic interference, resistance to corrosive environments, and high sensitivity, this humidity sensor has various applications. In soil moisture sensing, this humidity sensor can avoid the interference caused by compounds in soil water. For electrical transformer moisture sensing, this humidity sensor can avoid the effect of electromagnetic fields.
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Furness, Charles Zachary. "Parameter identification of a flexible beam using a modal domain optical fiber sensor." Thesis, Virginia Tech, 1990. http://hdl.handle.net/10919/42058.
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An optical fiber sensor is used for identification of a cantilevered beam under conditions of various concentrated mass loadings. A model of the sensor as well as the dynamic system is developed and used to test the reliability of the identification. Input/output data from an experiment is gathered and used in the identification. A survey of the existing areas of damage detection and parameter identification is included, along with suggestions for incorporating fiber optic sensors into existing techniques. The goal of this research was to show that the fiber sensor can be used for identification purposes, and that it is sensitive to parameter changes within the system (in this case concentrated mass changes).
Master of Science
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Silva, Jean Carlos Cardozo da. "Monitoração de vibrações de estruturas com o emprego de sensores em fibra óptica." Centro Federal de Educação Tecnológica do Paraná, 2005. http://repositorio.utfpr.edu.br/jspui/handle/1/79.
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Este trabalho tem por objetivo analisar as perspectivas do estudo de vibrações de
estruturas, empregando sistemas sensores baseados em redes de Bragg em fibras óticas. O entendimento das vibrações nas estruturas possibilita o estudo de novos materiais e de novos sistemas construtivos que possam otimizar o dimensionamento e a segurança nos projetos de engenharia. Para as medidas de vibração é apresentado um sistema de leitura de redes de Bragg que tem como características o baixo custo e a facilidade de implementação, quando comparado a outros instrumentos. O aparelho pode ser acoplado a sistemas de aquisição comerciais, pois o sinal analógico de saída está condicionado entre 0 V e 5 V. Os resultados obtidos demonstram a capacidade do sistema em monitorar vibrações em diferentes tipos de
materiais, tais como: madeira, aço, concreto e osso. Os resultados das medições feitas com
modelos de laboratório mostram-se promissores na análise de vibrações em estruturas, quando comparados aos obtidos por sensores comerciais dos tipos, extensômetro elétrico de
resistência e acelerômetro. Para além de estruturas civis, foram realizados estudos para o desenvolvimento de uma nova técnica de ensaio, in vitro, para caracterizar um novo conceito de implante dentário. Os resultados de ensaios de vibrações livres foram realizados com uma barra metálica,
com vigas de madeira laminada colada, com vigas de concreto e implantes dentários onde as redes de Bragg foram empregadas. Esses resultados demonstram a capacidade do sensor em monitorar os efeitos de degradação das estruturas através de diferentes técnicas de análise modal.This work deals with the analysis of perspectives of dynamic study in structures using a sensor system based on fibre optic Bragg gratings. The understanding of vibrations in structures enables the development of new materials, and of new design concepts that improves the sizing and security in engineering projects. The vibration measurements are carried out with a fibre optic Bragg grating demodulation system. The system has a low cost and easiness of implementation when compared to other available instruments. The output range signal of the instrument is between 0 V to 5 V, compatible to standard PC interfacing systems. The results show that the system is able to monitor vibrations in different types of materials, such as wood, steel, reinforced concrete and bone. The sensor is compared to commercial sensors (strain gauges and accelerometer). Beyond of civil structure, studies have been carried out to develop a technique, in vitro, to evaluate a new dental implant concept. The modal analysis techniques employed in the characterization of the different structures studied show the necessity of instrumentation able to measure low amplitude signals with high signal noise ratio. These characteristics are considered essential in material degradation studies by modal analysis technique.
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Wang, Wei-Chih. "A study of fluid viscosity and flow measurement using fiber-optic transducers /." Thesis, Connect to this title online; UW restricted, 1996. http://hdl.handle.net/1773/5908.
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Luanje, Appolinaire Tifang. "INTEGRATED OPTICAL FIBER RAMAN SENSOR FOR CRYOGENIC APPLICATION." MSSTATE, 2008. http://sun.library.msstate.edu/ETD-db/theses/available/etd-04042008-155057/.
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An integrated fiber optical Raman sensor was designed for real-time, non intrusive detection of liquid and gaseous mixtures at high pressure and high flow rates. The integrated sensor employs a high-power solid-state pumped Nd:YAG frequency doubled (532nm) laser (3W), a modified In Photonics Raman probe which has built-in Raman signal filter optics, and two high-resolution spectrometers and photomultiplier tubes (PMT) with selected bandpass filters to collect both N2 and O2 Raman signals. The detection unit was also integrated with Lab View software interfaced PMT modules for fast data acquisition.
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Geddis, Demetris Lemarcus. "Single fiber bi-directional OE links using 3D stacked thin film emitters and detectors." Diss., Available online, Georgia Institute of Technology, 2004:, 2003. http://etd.gatech.edu/theses/available/etd-04082004-180141/unrestricted/geddis%5Fdemetris%5Fl%5F200312%5Fphd.pdf.
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