Página 1 dos resultados de 17 itens digitais encontrados em 0.007 segundos

Durability Tests of a Fiber Optic Corrosion Sensor

Wan, Kai Tai; Leung, Christopher K.Y.
Fonte: Molecular Diversity Preservation International (MDPI) Publicador: Molecular Diversity Preservation International (MDPI)
Tipo: Artigo de Revista Científica
Publicado em 16/03/2012 EN
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46.3%
Steel corrosion is a major cause of degradation in reinforced concrete structures, and there is a need to develop cost-effective methods to detect the initiation of corrosion in such structures. This paper presents a low cost, easy to use fiber optic corrosion sensor for practical application. Thin iron film is deposited on the end surface of a cleaved optical fiber by sputtering. When light is sent into the fiber, most of it is reflected by the coating. If the surrounding environment is corrosive, the film is corroded and the intensity of the reflected signal drops significantly. In previous work, the sensing principle was verified by various experiments in laboratory and a packaging method was introduced. In this paper, the method of multiplexing several sensors by optical time domain reflectometer (OTDR) and optical splitter is introduced, together with the interpretation of OTDR results. The practical applicability of the proposed sensors is demonstrated in a three-year field trial with the sensors installed in an aggressive marine environment. The durability of the sensor against chemical degradation and physical degradation is also verified by accelerated life test and freeze-thaw cycling test, respectively.

Fiber Sensor Systems Based on Fiber Laser and Microwave Photonic Technologies

Fu, Hongyan; Chen, Daru; Cai, Zhiping
Fonte: Molecular Diversity Preservation International (MDPI) Publicador: Molecular Diversity Preservation International (MDPI)
Tipo: Artigo de Revista Científica
Publicado em 27/04/2012 EN
Relevância na Pesquisa
46.44%
Fiber-optic sensors, especially fiber Bragg grating (FBG) sensors are very attractive due to their numerous advantages over traditional sensors, such as light weight, high sensitivity, cost-effectiveness, immunity to electromagnetic interference, ease of multiplexing and so on. Therefore, fiber-optic sensors have been intensively studied during the last several decades. Nowadays, with the development of novel fiber technology, more and more newly invented fiber technologies bring better and superior performance to fiber-optic sensing networks. In this paper, the applications of some advanced photonic technologies including fiber lasers and microwave photonic technologies for fiber sensing applications are reviewed. FBG interrogations based on several kinds of fiber lasers, especially the novel Fourier domain mode locking fiber laser, have been introduced; for the application of microwave photonic technology, examples of microwave photonic filtering utilized as a FBG sensing interrogator and microwave signal generation acting as a transversal loading sensor have been given. Both theoretical analysis and experimental demonstrations have been carried out. The comparison of these advanced photonic technologies for the applications of fiber sensing is carried out and important issues related to the applications have been addressed and the suitable and potential application examples have also been discussed in this paper.

Spatial Frequency Multiplexing of Fiber-Optic Interferometric Refractive Index Sensors Based on Graded-Index Multimode Fibers

Liu, Li; Gong, Yuan; Wu, Yu; Zhao, Tian; Wu, Hui-Juan; Rao, Yun-Jiang
Fonte: Molecular Diversity Preservation International (MDPI) Publicador: Molecular Diversity Preservation International (MDPI)
Tipo: Artigo de Revista Científica
Publicado em 12/09/2012 EN
Relevância na Pesquisa
46.57%
Fiber-optic interferometric sensors based on graded-index multimode fibers have very high refractive-index sensitivity, as we previously demonstrated. In this paper, spatial-frequency multiplexing of this type of fiber-optic refractive index sensors is investigated. It is estimated that multiplexing of more than 10 such sensors is possible. In the multiplexing scheme, one of the sensors is used to investigate the refractive index and temperature responses. The fast Fourier transform (FFT) of the combined reflective spectra is analyzed. The intensity of the FFT spectra is linearly related with the refractive index and is not sensitive to the temperature.

Pico-strain multiplexed fiber optic sensor array operating down to infra-sonic frequencies

Littler, I C M; Gray, Malcolm B; Chow, Jong; Shaddock, Daniel; McClelland, David
Fonte: http://www.osa.org/ Publicador: http://www.osa.org/
Tipo: Journal article; Published Version; Optical Society of America Formato: 11 pages
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66.17%
An integrated sensor system is presented which displays passive long range operation to 100 km at pico-strain (pε) sensitivity to low frequencies (4 Hz) in wavelength division multiplexed operation with negligible cross-talk (better than −75 dB). This has been achieved by prestabilizing and multiplexing all interrogation lasers for the sensor array to a single optical frequency reference. This single frequency reference allows each laser to be locked to an arbitrary wavelength and independently tuned, while maintaining suppression of laser frequency noise. With appropriate packaging, such a multiplexed strain sensing system can form the core of a low frequency accelerometer or hydrophone array.

Multiplexación en longitud de onda de sensores fotónicos híbridos de diferentes parámetros

Labiano, Iker; Abad Valtierra, Silvia; López Amo, Manuel; Jáuregui Misas, César; Quintela Incera, Antonio; López Higuera, José Miguel
Fonte: Universidade de Cantabria Publicador: Universidade de Cantabria
Tipo: info:eu-repo/semantics/conferenceObject; publishedVersion
SPA
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26.02%
A fiber-optic-sensor multiplexing network for measuring different parameters is demonstrated. Temperature, strain and displacement have been sensed employing fiber tapers and Bragg gratings. Limitations on the insertion loss and operation range of the sensors are analysed, as well as crosstalk effects on the network.

Temperature level optical fiber sensor using shape memory alloy wires

López Higuera, José Miguel; Rodríguez Cobo, Luis; Quintela Incera, Antonio; Hidalgo-Gato García, Rafael; Shokry Girgis Roufael, Hany
Fonte: SPIE Society of Photo-Optical Instrumentation Engineers Publicador: SPIE Society of Photo-Optical Instrumentation Engineers
Tipo: info:eu-repo/semantics/conferenceObject; publishedVersion
ENG
Relevância na Pesquisa
46.19%
A temperature Level fiber Optic transducer based on a fiber grating-shape Memory Alloy wire structure (LOMA) is presented in this paper. The basic sensors system works as an on/off optical device: only output light is offered by the device when the structure temperature (T) is over a given temperature level (T>TL). The proposed fiber structure can be used as point or as quasi-distributed sensors systems exploiting its optical multiplexing capacities. The simple and cost effective device is successfully demonstrated in the laboratory.

Switchable fiber optic laser system for high and low-strain fiber optic sensors remote multiplexing

Rota Rodrigo, Sergio; Rodríguez Cobo, Luis; Quintela Incera, María Ángeles; López Higuera, José Miguel; López Amo, Manuel
Fonte: SPIE Society of Photo-Optical Instrumentation Engineers Publicador: SPIE Society of Photo-Optical Instrumentation Engineers
Tipo: info:eu-repo/semantics/conferenceObject; publishedVersion
ENG
Relevância na Pesquisa
76.53%
In this paper, a 50 Km remote and switchable fiber optic sensing system based on an erbium doped fiber ring laser is proposed. The system allows the integration of different interrogation methods based on the detection of wavelength or amplitude variations of the laser. This integration is carried out by sequentially activating different ring cavities by using an optical switch. With this scheme, the maximum gain zone of the erbium doped fiber amplifier can be used to increase the distance of the sensor system. A bending intensity sensor and a FBG based strain sensor were successfully tested for high and low-strain measurements respectively. This system includes all the active elements inside the monitoring station, enabling the remote monitoring of the sensors.

Electrical FIR Filter With Optical Coefficients for Self-Referencing WDM Intensity Sensors

Montalvo, Julio; Araujo, F.M.; Ferreira, L.A.; Vázquez, Carmen; Baptista, José Manuel
Fonte: IEEE Publicador: IEEE
Tipo: Artigo de Revista Científica Formato: application/pdf
Publicado em 01/01/2008 ENG
Relevância na Pesquisa
56.19%
In this letter, a novel radio-frequency finite impulse reponse (FIR) electrooptical configuration for self-referencing optical wavelength-division-multiplexed intensity sensors is reported. By employing the proposed low-cost electronic FIR filter at the reception stage, the use of a 14-km fiber delay coil is avoided for a 2-kHz modulation frequency, preserving sensitivity and self-reference. The technique is analyzed following the Z-transform formalism and measurements validating the theoretical model are reported.

Self-referencing techniques in photonics sensors and multiplexing

Vázquez, Carmen; Montalvo, Julio; Sánchez Montero, David; Contreras Lallana, Pedro
Fonte: SPIE Publicador: SPIE
Tipo: Conferência ou Objeto de Conferência Formato: application/pdf
Publicado em 12/06/2007 ENG
Relevância na Pesquisa
56.53%
A short review of self-reference techniques for remote fiber-optic intensity sensors and possible integration in multiplexing sensor networks is reported. Special focus is given to developments on radio-frequency (RF) source modulation techniques in interferometric configurations operating under incoherent regime. Experimental results on ring resonator (RR) configurations in transmission and reflection modes are included. Sensitivity, optimum insertion losses and robustness to intensity error fluctuations are reported. Sensors are interrogated at two sub carrier frequencies having a high rejection of interference from laser source intensity fluctuations and loss in the fiber lead. Dependence on source coherence is also analysed.Scalable self-referencing sensor networks with low insertion losses implemented in Coarse Wavelength Division Multiplexing (CWDM) technology are reported. The possibility of remote self-referenced measurements using a full-duplex fiber down-lead tenths of kilometers long with no need for optical amplification is also described. Fiber Bragg gratings (FBG) are used in the reflection configuration, thus increasing the sensitivity of the optical transducers. Low-cost off-the-shelf devices in CWDM and DWDM technology can be used to implement and scale the network.; Applications to specific photonic sensors are also envisaged and these techniques can be used in networks of microfiber loop resonators...

Técnica de medida con auto-referencia para sensores ópticos de intensidad mediante procesado digital de señal e instrumentación virtual

Valverde Marín, Laura Guiomar
Fonte: Universidade Carlos III de Madrid Publicador: Universidade Carlos III de Madrid
Tipo: info:eu-repo/semantics/bachelorThesis; info:eu-repo/semantics/masterThesis Formato: application/pdf
SPA
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26.42%
Esta memoria presenta el proyecto fin de carrera titulado “ Técnica de medida con auto-referencia para sensores ópticos de intensidad mediante procesado digital de señal e instrumentación virtual" realizado en el departamento de Tecnología Electrónica de la Universidad Carlos III de Madrid bajo la supervisión del Prof. David Sánchez Montero. El proyecto se basa en la tesis fin de máster “Coarse WDM passive optical networking of self-referenced fiber-optic intensity sensors with reconfigurable characteristics” de David Sánchez Montero, cuya investigación se centra en el desarrollo de redes pasivas de sensores de intensidad óptica con auto-referencia para topologías de multiplexación WDM. La configuración electro-óptica para redes CWDM de sensores ópticos de intensidad basada en redes de Bragg y con modulación en radio frecuencia ha sido verificada usando un amplificador de Lock-in en recepción junto con líneas de retardo electrónicas implementadas mediante amplificadores operacionales, resistencias y condensadores comerciales de bajo coste [1]. El presente proyecto surge por la propuesta de mejora empleando técnicas de procesado digital e instrumentación virtual en la etapa de recepción para evitar el uso del amplificador de Lock-in y las etapas de retardo electrónicas en recepción. El principal objetivo de este trabajo es el diseño de aplicaciones que implementen las técnicas de medida con auto-referencia para poder realizar la interrogación remota de sensores ópticos de intensidad de una manera eficaz...

Radio-Frequency Self-Referencing Technique With Enhanced Sensitivity for Coarse WDM Fiber Optic Intensity Sensors

Montalvo, Julio; Frazão, Orlando; Santos, José Luis; Vázquez, Carmen; Baptista, José Manuel
Fonte: IEEE Publicador: IEEE
Tipo: Artigo de Revista Científica Formato: application/pdf
Publicado em 01/03/2009 ENG
Relevância na Pesquisa
46.34%
A self-referenced passive optical network (PON) with coarse wavelength division multiplexing (CWDM) is reported for remotely addressing optical intensity sensors with enhanced sensitivity. The self-referencing remote configuration is described as a finite-impulse-response (FIR) filter in reflective operation using two fiber Bragg gratings (FBG) and a fiber delay line. The antisymmetrical phase response of the configuration permits to achieve a self-referencing measurement parameter two times more sensitive than reported previously. To enhance the power budget of the network, CWDM devices with low insertion losses are used for spectral splitting of a radio-frequency (RF) modulated broadband light source (BLS). The network topology and the sensor's interrogation technique are theoretically analyzed and experimental results validating the models are reported.

A technique for multiplexing 3x3-coupler terminated interferometric fiber-optic sensors

Reid, Gregory John.
Fonte: Monterey, California. Naval Postgraduate School Publicador: Monterey, California. Naval Postgraduate School
Tipo: Tese de Doutorado Formato: 99 p. :|bill.
EN_US
Relevância na Pesquisa
96.58%
Approved for public release; distribution is unlimited.; This thesis investigates the multiplexing of Mach-Zehnder type 3x3 terminated fiber-optic sensors demodulated by either 'quadrature'or'symmetric' methods using intensity modulation of the source. 3x3-couplers produce signals that permit unmodulated passive demodulation of interferometric signals. The theory is described and the results of a 2xl element array optical demonstration are presented. Possible architectures using this demultiplexing technique are presented for several applications with different return line requirements. The technique was successfully demonstrated and warrants further investigation to increase the number of sensors and reduce the number of return lines for specific applications. The multiplexing technique presents the opportunity for possible cost savings over other phase generated carrier techniques, which require wavelength modulation of the source, and significant optical path differences in the interferometers, and are therefore constrained to presently very expensive sources. The technique presented uses compatible low coherent laser sources such as Compact Disc quality (830 nm) devices.; Lieutenant, Royal Australian Navy

STUDIO E SPERIMENTAZIONE DI MATERIALI E SENSORI INTELLIGENTI BASATI SU TECNOLOGIA FBG

VENDITTOZZI, CRISTIAN
Fonte: La Sapienza Universidade de Roma Publicador: La Sapienza Universidade de Roma
Tipo: Tese de Doutorado
IT
Relevância na Pesquisa
36.11%
I sensori FBG vengono utilizzati per il monitoraggio dello stato dell’integrità strutturale dei componenti industriali. Essi mostrano diversi vantaggi rispetto ai sensori tradizionali. Il più immediato è la loro possibilità di lavorare in presenza di interferenze elettromagnetiche (per quanto elevate possano essere) ed in altre condizioni avverse, in ambienti particolarmente aggressivi (harsh) in cui si trovino in presenza di temperature elevate (o ancora peggio forti escursioni termiche) pressioni elevate ed elevati valori di umidità relativa (RH%); non mostrano problemi a lavorare in ambienti sporchi, presenza di solventi, grasso o polvere e concentrazioni di specie inquinanti. Sono caratterizzati da una elevata sensibilità nella misura, in particolare di grandezze quali deformazioni e temperatura e l’evoluzione degli strumenti di elaborazione del segnale ottico consentono oggi una straordinaria risoluzione di tali misure. Grazie alle loro dimensioni contenute e al peso ridotto hanno mostrato una ottima affinità all’inglobamento all’interno dei materiali oltre al mero incollaggio superficiale. La possibilità consentita dalla multiplexabilità dei sensori...

MULTIMODE DEVICES IN COMMUNICATION AND SENSING SYSTEMS

Gong, Xiaoyu
Fonte: Quens University Publicador: Quens University
Tipo: Tese de Doutorado
EN; EN
Relevância na Pesquisa
36.25%
Multimode devices play an increasingly important role in both communication and sensing systems. Mode division multiplexing (MDM) in multimode fiber (MMF) is becoming a promising method to further increase the capacity of optical transmission link with a controllable mode coupler. Similarly, optic sensors based on core-cladding-mode interference can be widely used in measurement of refractive index (RI), temperature and strain. Fiber Bragg gratings (FBGs) in single mode operation have been extensively studied as in-line optical components for both communication and sensing applications. In recent years, research has been extended to FBGs in few-mode operation as mode couplers in MDM applications. Experimentally, mode conversion from fundamental linear polarization (LP) mode LP01 to higher order LP11 mode in two-mode FBG (TMFBG) has been observed. Index asymmetry and electric field distortion induced by ultraviolet (UV) side illumination in fabrication of FBG make the two modes no longer orthogonal. However, its spectrum analysis mainly depends on experimental data and software simulation using the complex finite element method (FEM). Here a simpler theoretical model based on coupled mode theory (CMT) and Runge-Kutta method (RKM) is proposed. An analytical expression of the mode coupling coefficient is derived and the modeling results match very well with experimental data. Abrupt fiber tapers allow power transfer between core and cladding modes and show promise as RI sensing components when two abrupt tapers are cascaded into an in-line Mach-Zehnder interferometer (MZI). The main advantage of the MZI taper sensor is its low manufacturing cost. However...

Fiber optic sensors and self-reference techniques for temperature measurements in different industrial sectors

Tapetado Moraleda, Alberto
Fonte: Universidade Carlos III de Madrid Publicador: Universidade Carlos III de Madrid
Tipo: Tese de Doutorado
ENG
Relevância na Pesquisa
96.78%
El objetivo de este trabajo se centra especialmente en el desarrollo de sensores de fibra óptica y técnicas de autoreferencia para la medida de la temperatura en diferentes entornos industriales. El primer objetivo de este trabajo consiste en el diseño y desarrollo de un sensor de fibra óptica de bajo coste para la medida de la temperatura en transformadores de potencia y aplicaciones biomédicas. En estas aplicaciones, el uso de sensores de temperatura tradicionales resulta inadecuado debido a la presencia de fuertes interferencias electromagnéticas que pueden perturbar la lectura de la temperatura. Uno de los requisitos fundamentales para diseñar un sensor de temperatura que pueda usarse en aplicaciones biomédicas es el uso de materiales biocompatibles en su fabricación. En este sentido, una configuración simple que permite cumplir con los requisitos mencionados anteriormente es la modulación por intensidad en fibras poliméricas. Este tipo de sensores basan la lectura de la temperatura en medir las variaciones de potencia óptica en función de los cambios de temperatura que se aplican sobre el sensor. En este contexto, el uso de la tecnología asociada con la fibra óptica de plástico ofrece ventajas competitivas frente a otros materiales...

Multiplexed Fiber Optic Sensor Array for Geophysical Survey

Littler, Ian; Chow, Jong; Shaddock, Daniel; McClelland, David; Gray, Malcolm
Fonte: SPIE - The International Society for Optical Engineering Publicador: SPIE - The International Society for Optical Engineering
Tipo: Conference paper
Relevância na Pesquisa
66.38%
We present the latest results from our multiplexed fiber optic Fabry-Perot acoustic sensor array using modulated lasers. It offers the possibility of a robust, reliable and easy to deploy system, meeting the demands of geophysical survey.

Structural and environmental monitoring of tracker and vertex systems using Fiber Optic Sensors

Moya, David; Vila, Iván
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 01/03/2012
Relevância na Pesquisa
56.34%
Fibre optic sensors (FOS) are an established technique for environmental and deformation monitoring in several areas like civil engineering, aerospace, and energy. Their immunity to electromagnetic and magnetic fields and nuclear environments, its small size, multiplexing capability and the possibility to be embedded make them an attractive technology for the structural and environmental monitoring of collider particle physics experiments. Between all the possible Fibre Optic sensors FBGs (Fiber Bragg Grating) seems to be the best solution for HEP applications. The first step was to characterize FBG sensors for it use in High Energy Physics environment. During last two years we have checked the resistance of the Fibre Bragg Grating sensors to radiation. Two irradiation campaigns with protons have been done at CNA (Centro Nacional de Aceleradores). In the near future these sensors are being planned to be used in detectors (the closest one Belle II.). Several work on integration issues in Belle II PXD-SVD, and checking for environmental and deformation monitoring in the detectors inner part has been done.; Comment: LCWS11 International Workshop in Future Linear colliders