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Beadle, Brad Michael. "Fiber optic sensor for ultrasound." Diss., Georgia Institute of Technology, 2002. http://hdl.handle.net/1853/17869.
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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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Maier, Eric William. "Buried fiber optic intrusion sensor." Thesis, Texas A&M University, 2004. http://hdl.handle.net/1969.1/425.
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A distributed fiber optic intrusion sensor capable of detecting intruders from the pressure of their weight on the earth's surface was investigated in the laboratory and in field tests. The presence of an intruder above or in proximity to the buried sensor induces a phase shift in light propagating along the fiber which allows for the detection and localization of intrusions. Through the use of an ultra-stable erbium-doped fiber laser and phase sensitive optical time domain reflectometry, disturbances were monitored in long (several km) lengths of optical fiber. Narrow linewidth and low frequency drift in the laser were achieved through a combination of optical feedback and insulation of the laser cavity against environmental effects. The frequency drift of the laser, characterized using an all-fiber Mach Zehnder interferometer, was found to be less than 1 MHz/min, as required for operation of the intrusion detection system. Intrusions were simulated in a laboratory setting using a piezoelectric transducer to produce a controllable optical phase shift at the 2 km point of a 12 km path length. Interrogation of the distributed sensor was accomplished by repetitively gating light pulses from the stable laser into the sensing fiber. By monitoring the Rayleigh backscattered light with a photodetector and comparing traces with and without an induced phase shift, the phase disturbances were detected and located. Once the feasibility of such a sensor was proven in the laboratory, the experimental set up was transferred to Texas A&M's Riverside Campus. At the test site, approximately 40 meters of fiber optic cable were buried in a triangle perimeter and then spliced into the 12 km path length which was housed inside the test facility. Field tests were conducted producing results comparable to those found in the laboratory. Intrusions over this buried fiber were detectable on the φ-OTDR trace and could be localized to the intrusion point. This type of sensor has the potential benefits of heightened sensitivity, covertness, and greatly reduced cost over the conventional seismic, acoustic, infrared, magnetic, and fiber optic sensors for monitoring long (multi-km) perimeters.
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Goyal, Sandeep. "Fiber optic current sensor network." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp05/mq24716.pdf.
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Wang, Xingwei. "Optical Fiber Tip Pressure Sensor." Thesis, Virginia Tech, 2004. http://hdl.handle.net/10919/35490.
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Miniature pressure sensors which can endure harsh environments are a highly sought after goal in industrial, medical and research fields. Microelectromechanical systems (MEMS) are the current methods to fabricate such small sensors. However, they suffer from low sensitivity and poor mechanical properties.
To fulfill the need for robust and reliable miniature pressure sensors that can operate under high temperatures, a novel type of optical fiber tip sensor only 125μm in diameter is presented in this thesis. The essential element is a piece of hollow fiber which connects the fiber end and a diaphragm to form a Fabry-Pérot cavity. The all-fused-silica structure fabricated directly on a fiber tip has little temperature dependence and can function very well with high resolution and accuracy at temperatures up to 600ï °C. In addition to its miniature size, its advantages include superior mechanical properties, biocompatibility, immunity to electromagnetic interference, disposability and cost-effective fabrication.
The principle of operation, design analysis, fabrication implementation and performance evaluation of the sensor are discussed in detail in the following chapters.
Master of Science
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Ipson, Benjamin L. "Polarimetric Temperature Sensor Using Core-replaced Fiber." Diss., CLICK HERE for online access, 2004. http://contentdm.lib.byu.edu/ETD/image/etd606.pdf.
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Andrews, Jeffrey Pratt. "Longitudinal misalignment based strain sensor." Thesis, Virginia Tech, 1989. http://hdl.handle.net/10919/43283.
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A practical fiber optic strain sensor has been developed to measure strains in the range of 0.0 to 2.0 percent strain with a resolution ranging between 10 and 100 microstrain depending on sensor design choices. This intensity based sensor measures strain by monitoring strain induced longitudinal misalignment in a novel fiber interconnection. This interconnection is created by aligning fibers within a segment of hollow core fiber. Related splice loss mechanisms are investigated for their effect on resolution. The effect of gauge length and launch conditions are also investigated.
Master of Science
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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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Lee, Shiao-Chiu. "Axial offset effects upon optical fiber sensor and splice performance." Thesis, Virginia Polytechnic Institute and State University, 1985. http://hdl.handle.net/10919/91128.
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A kind of intensity modulated fiber sensor utilizing axial offset parameter is proposed. The theoretical analysis and experimental characteristics of this sensor are described.
All the theoretical results derived in this thesis are based on assuming a uniform power distribution in the fibers. An expression of coupling efficiency of central dipped parabolic graded index fibers due to axial offset is derived. The results show less sensitivity to axial offset for the central dipped fibers than for the parabolic profile fibers without a dip. Expressions of coupling efficiency of graded index fibers due to axial offset for several different values of a are also derived. The results show that sensitivity increases as the value of a decreases. A general expression of coupling efficiency which is valid for small values of axial offset is derived. This expression exhibits a linear relationship between coupling efficiency and small axial offset.
Coupling efficiencies versus fiber end separation and axial offset of step index fibers have been measured. The measurements show that coupling efficiency is much more sensitive to axial offset than end separation. A simple construction of the axial offset fiber sensor is described. An approximate linear relationship between the output power and the mechanical loading has been obtained for this sensor. Several ways of increasing the sensitivity of this sensor are discussed.M.S.
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Rønnekleiv, Erlend. "Fiber DFB Lasers for Sensor Applications." Doctoral thesis, Norwegian University of Science and Technology, Faculty of Information Technology, Mathematics and Electrical Engineering, 2000. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-498.
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Gaikwad, Parikshit S. "Chemically deposited optical fiber humidity sensor." Master's thesis, Mississippi State : Mississippi State University, 2003. http://library.msstate.edu/etd/show.asp?etd=etd-06092003-141607.
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Miller, Mark S. "Optical fiber-based corrosion sensor systems." Diss., This resource online, 1995. http://scholar.lib.vt.edu/theses/available/etd-03042009-041455/.
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Kiliç, Onur. "Fiber based photonic-crystal acoustic sensor /." May be available electronically:, 2008. http://proquest.umi.com/login?COPT=REJTPTU1MTUmSU5UPTAmVkVSPTI=&clientId=12498.
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Chen, Raymond M. Eng Massachusetts Institute of Technology. "Photoacoustic photonic crystal fiber gas sensor." Thesis, Massachusetts Institute of Technology, 2007. http://hdl.handle.net/1721.1/41258.
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Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2007.Includes bibliographical references (p. 89-93).
Photoacoustic spectroscopy (PAS) is a form of laser spectroscopy that has demonstrated very high sensitivity for gas detection. Typically, PAS involves the absorption of a modulated laser beam by the gas species of interest, and the subsequent generation of acoustic waves at the modulation frequency. The amplitude of the acoustic signal, which can be measured by a microphone, can be amplified by several orders of magnitude with a properly designed gas cell used as an acoustic resonator. In recent times, hollow-core photonic crystal fiber (HC-PCF) has emerged as superior gas cell for standard absorption-based laser spectroscopy due to its small size, compatibility with fiber-based optical components, and easily attainable long light-gas interaction path lengths. However, the possibility of utilizing HC-PCF as a gas cell for PAS has yet to be explored. The size and structure of HC-PCF demands that a new method of PA signal detection must be proposed, because the conventional use of microphones for PAS is not applicable. This thesis describes the development of a proposed novel use of HC-PCF as a PA gas cell from theoretical support to experimental realization. A number of unresolved experimental issues prevented data on the performance of the constructed system from being obtained. These problems are discussed, and recommendations for further study, including several proposed measures to overcome these experimental issues, are made in the conclusion to the thesis.
by Raymond Chen.
M.Eng.
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Hernandez, Felipe Bueno. "Sensor de força utilizando Fiber taper." Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/18/18149/tde-27072016-074912/.
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Este trabalho teve por objetivo desenvolver e caracterizar um sensor de força utilizando uma fibra óptica modificada pelo processo conhecido como Fiber tapering. A fibra quando modificada deixa exposto o campo evanescente, o que a torna sensível a influências externas, e a luz guiada na fibra pode vir a sofrer reflexão interna total frustrada ao entrar em contato com materiais. Ao envolver a região modificada por um material elastomérico, a área de contato e consequentemente a atenuação torna-se uma função da intensidade da força aplicada, possibilitando então relacionar a força a atenuação da luz. Baseando-se nesse efeito, foi criado um sensor de dimensões reduzidas, de rápida resposta, linear, altamente sensível e de boa repetibilidade. Foi criado também um circuito eletrônico utilizando amplificadores operacionais para a aquisição e processamento do sinal proveniente da fibra e selecionado um sensor comercial comum para a realização de experimentos e comparações. Ambos os sensores foram posicionados sobre uma balança de precisão e submetidos a diversos esforços obtendo-se dados sobre a resposta estática. Em seguida utilizando um shaker eletrodinâmico foram medidos os tempos de resposta a uma entrada degrau, e realizando esforços repetitivos foram analisados os desvios das medidas lidas pelos sensores.The aim of this research was to develop and characterize a force sensor using a modified optical fiber by a process known as Fiber tapering. The modified fiber leaves the evanescent field exposed and prone to external influences and the guided light may suffer frustration of total internal reflection upon contact with materials. When covering the modified fiber section with an elastomeric material, the contact area and therefore the attenuation becomes a function of the applied pressure, making it possible to relate force to attenuation in light intensity. Based on this effect, a small sensor was created, having a quick response time, with high linearity, high sensitivity and good repeatability. Along with the sensor, an electronic circuit using operational amplifiers was designed for acquisition and processing of the signal obtained from the optical fiber. In addition, in order to perform experiments and comparisons, a standard force sensor was chosen. Both sensors were placed over a precision weighing scale and had different intensities of force applied on them, and after that, data regarding static measurements was gathered. The response time was obtained using an electrodynamic shaker and applying a step input. Furthermore, data was gathered about the deviations on the measurements by performing a repetitive set of compressions.
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Chen, Qiao. "ESA based fiber optical humidity sensor." Thesis, Virginia Tech, 2002. http://hdl.handle.net/10919/10134.
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Several techniques for measuring humidity are presented. The goal of the study is to use the electrostatic self-assembled monolayer synthesis process to fabricate a Fabry-Parot Cavity based optical fiber humidity sensor. The sensing scheme bases on the refractive index change with relative humidity of the film applied to the end of optical fiber. That is, the change in reflected optical power indicates certain humidity. To achieve this, some chemicals induce on specific coating materials were applied at the end of optical fiber. In this thesis, experimental results are given to prove that the humidity sensor has high sensitive and fast response time. Furthermore, we investigate the potential for the use of human breathing monitoring and air flow rate detection. Results from preliminary tests of each are given.Master of Science
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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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Sethuraman, Gopakumar. "Fiber Bragg Grating (FBG) Based Chemical Sensor." VCU Scholars Compass, 2008. http://scholarscompass.vcu.edu/etd/1575.
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In this work, reagentless fiber optic-based chemical sensors for water quality testing were fabricated by coating fiber Bragg gratings with the glassy polymer cellulose acetate. With this polymeric matrix capable of localizing or concentrating chemical constituents within its structure, immersion of the coated grating in various chemical solutions causes the rigid polymer to expand and mechanically strain the glass fiber. The corresponding changes in the periodicity of the grating subsequently result in altered Bragg-reflected responses. A high-resolution tunable fiber ring laser interrogator is used to obtain room temperature reflectance spectrograms from two fiber gratings at 1550 nm and 1540 nm wavelengths. Rapidly swept measurements of the full spectral shapes yield real-time chemical detection and identification. With deionized water as a reference, wavelength shifts in the reflectivity transition edge from –82 pm to +43 pm and changes in response bandwidth from –27 pm to +42 pm are used to identify uniquely a diverse selection of chemical analytes.
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Cassino, Christopher Daniel. "Detection of fiber fracture in Unidirectional Fiber Reinforced Composites using an In-Plane Fiber Optic Sensor." Thesis, Virginia Tech, 2002. http://hdl.handle.net/10919/32419.
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Fiber reinforced polymers (FRP) are an efficient and inexpensive method of repairing deteriorating infrastructure. FRP sheets can be applied to spalling bridge sections and columns to prevent further deterioration and increase stiffness. However, the effect of the environment on the long-term durability of FRP and how the various damage mechanisms initiate and develop are not known. Systems for structural health monitoring are being sought as a means of managing important components in transportation systems as assets in light of modern life cycle cost concepts. This study characterizes a fiber optic sensor for use in detecting acoustic emissions (AE) in FRP. The results of AE analysis (signal amplitude, frequency spectra, MARSE, and in-plane displacement) caused by simulated fiber fracture experiments and other types of mechanical loading in FRP test coupons are reported. The applications to the development of FRP structural health monitoring systems are also discussed.Master of Science
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Wavering, Thomas A. "Optical Path Length Multiplexing of Optical Fiber Sensors." Thesis, Virginia Tech, 1998. http://hdl.handle.net/10919/36037.
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Optical fiber sensor multiplexing reduces cost per sensor by designing a system that minimizes the expensive system components (sources, spectrometers, etc.) needed for a set number of sensors. The market for multiplexed optical sensors is growing as fiberoptic sensors are finding application in automated factories, mines, offshore platforms, air, sea, land, and space vehicles, energy distribution systems, medical patient surveillance systems, etc. Optical path length multiplexing (OPLM) is a modification to traditional white-light interferometry techniques to multiplex extrinsic Fabry-Perot interferometers and optical path length two-mode sensors. Additionally, OPLM techniques can be used to design an optical fiber sensor to detect pressure/force/acceleration and temperature simultaneously at a single point. While power losses and operating range restrictions limit the broadscale applicability of OPLM, it provides a way to easily double or quadruple the number of sensors by modifying the demodulation algorithm. The exciting aspect of OPLM is that no additional hardware is needed to multiplex a few sensors. In this way OPLM works with conventional technology and algorithms to drastically increase their efficiency. [1]Master of Science
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Zhu, Yizheng. "Miniature Fiber-Optic Sensors for High-Temperature Harsh Environments." Diss., Virginia Tech, 2007. http://hdl.handle.net/10919/27762.
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Measurement of physical parameters in harsh environments (high pressure, high temperature, highly corrosive, high electromagnetic interference) is often desired in a variety of areas, such as aerospace, automobile, energy, military systems, and industrial processes. Pressure and temperature are among the most important of these parameters. A typical example is pressure monitoring in jet engine compressors to help detect and control undesirable air flow instabilities, namely rotating stall and surge. However, the temperatures inside a compressor could reach beyond 600°C for today's large engines. Current fiber-optic sensor can operate up to about 300°C and even the most widely employed semiconductor sensors are limited below 500°C.
The objective of this research is to push the limit of fiber-optic sensing technology in harsh environment applications for both pressure and temperature measurements by developing novel sensing structures, fabrication techniques, and signal processing algorithms. An all-fused-silica pressure sensor has been demonstrated which is fabricated on the tip of a fiber with a diameter no larger than 125μm. The sensor was able to function beyond the current limit and operate into the 600~700°C range. Also a temperature sensor has been developed using sapphire fibers and wafers for ultra-high temperature measurement as high as 1600°C. This effort will generate more understanding regarding sapphire fiber's high temperature properties and could possibly lead to novel designs of pressure sensor for beyond 1000°C. Both sensors have been field tested in real-world harsh environments and demonstrated to be reliably and robust.
In this dissertation, the design, fabrication, and testing of the sensors are discussed in detail. The system and signal processing techniques are presented. The plan and direction for future work are also suggested with an aim of further pushing the operating limit of fiber-optic sensors.Ph. D.
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Bangert, Adam. "Fiber optic sensor prototype for breast cancer imaging." Connect to resource, 2006. http://hdl.handle.net/1811/6455.
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Thesis (Honors)--Ohio State University, 2006.Title from first page of PDF file. Document formatted into pages: contains 33 p.; also includes graphics. Includes bibliographical references (p. 20). Available online via Ohio State University's Knowledge Bank.
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Canalizo, M. Andres E. "Fiber optic current sensor network, innovations and applications." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0019/MQ48057.pdf.
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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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Ekestam, Henrik, and Jim Larsson. "Temperature sensor based on dual fiber Bragg gratings." Thesis, KTH, Tillämpad fysik, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-168137.
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The objective of the project was to examine if it was possible to develop a low-cost temperature sensor using dual fiber Bragg gratings (FBGs). The intention was to use one FBG as a reference and let the other FBG function as the sensor. The study shows that it is possible to characterize the temperature sensitivity of each FBG and use the reference to sweep over the applicable spectrum to find the Bragg-wavelength of the sensor. This could be done measuring only the total intensity instead of intensity per wavelength with an optical spectrum analyzer, and with high accuracy. Thus, it seems feasible to construct a low cost and accurate optical temperature sensor based on dual FBGs.Målet med projektet var att undersöka möjligheten att utveckla en lågkostnads-temperatursensor baserad på dubbla fiber Bragg-gitter (FBG). Syftet var att använda ett FBG som referens och låta det andra FBG:t fungera som sensor. Studien visar att det är möjligt att karaktärisera temperaturkänsligheten hos de båda FBG:erna och använda referensen för att svepa över den relevanta delen av spektrumet för att identifiera sensorns Bragg-våglängd. Det går att åstadkomma genom att mäta bara den totala intensiteten istället för intensitet per våglängsenhet med en optisk spektrumanalysator, och det går att göra med hög noggrannhet. Således ter det sig troligt att det till låg kostnad går att konstruera en precis optisk temperatursensor baserad på dubbla fiber Bragg-gitter.
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Tian, Zhipeng. "Sapphire Fiber Optic Sensor for High Temperature Measurement." Diss., Virginia Tech, 2018. http://hdl.handle.net/10919/91191.
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This dissertation focuses on developing new technologies for ultra-low-cost sapphire fiber-optic high-temperature sensors. The research is divided into three major parts, the souceless sensor, the simple Fabry-Perot (F-P) interrogator, and the sensor system.
Chapter 1 briefly reviews the background of thermal radiation, fiber optic F-P sensors, and F-P signal demodulation. The research goal is highlighted.
In Chapter 2, a temperature sensing system is introduced. The environmental thermal radiation was used as the broadband light source. A sapphire wafer F-P temperature sensor head was fabricated, with an alumina cap designed to generate a stable thermal radiation field. The radiation-induced optical interference pattern was observed. We demodulated the temperature sensor by white-light-interferometry (WLI). Temperature resolution better than 1°C was achieved.
Chapter 3 discusses a novel approach to demodulate an optical F-P cavity at low-cost. A simple interrogator is demonstrated, which is based on the scanning-white-light-interferometry (S-WLI). The interrogator includes a piece of fused silica wafer, and a linear CCD array, to transform the F-P demodulation from the optical frequency domain to the spatial domain. By using the light divergence of an optical fiber, we projected a tunable reference F-P cavity onto an intensity distribution along a CCD array. A model for S-WLI demodulation was established. Performance of the new S-WLI interrogator was investigated. We got a good resolution similar to the well-known traditional WLI.
At last, we were able to combine the above two technologies to a sapphire-wafer-based temperature sensor. The simple silica wafer F-P interrogator was optimized by focusing light to the image sensor. This approach improves the signal to noise ratio, hence allows the new integrator to work with the relatively weak thermal radiation field. We, therefore, proved in the experiment, the feasibility of the low-cost sourceless optical Fabry-Perot temperature sensor with a simple demodulation system.PHD
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Chen, Xiaopei. "Fiber Optic Pressure Sensor Fabrication Using MEMS Technology." Thesis, Virginia Tech, 2003. http://hdl.handle.net/10919/32744.
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A technology for fabricating fiber optic pressure sensors is described. This technology is based on intermediate-layer bonding of a fused silica ferrule to a patterned, micro-machined fused silica diaphragm, providing low temperature fabrication of optical pressure sensor heads that can operate at high temperature. Fused silica ferrules and fused silica diaphragms are chosen to reduce the temperature dependence. The fused silica diaphragms have been micro-machined using wet chemical etching in order to form extrinsic Fabry-Perot (FP) interferometric cavities. Sol-gel is used as an intermediate-layer for both fiber-ferrule bonding and ferrule-diaphragm bonding at relatively low temperature (250 °C). The pressure sensors fabricated in the manner can operate at temperatures as high as 600 °C.
The self-calibrated interferometric-intensity-based (SCIIB) technology, which combines fiber interferometry and intensity-based sensing method into a single sensor system, is used to test and monitor the pressure sensor signal. The light returned from the FP cavity is split into two channels. One channel with longer coherence length can test the effective interference generated by the FP cavity, while the other channel with shorter coherence length can get signal proportional only to the source power, fiber attenuation, and other optical losses. The ratio of the signals from the two channels can compensate for all unwanted factors, including source power variations and fiber bending losses. [11]Master of Science
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Schenström, Karl. "Biofunctionalization of a Fiber Optics-Based LSPR Sensor." Thesis, Linköpings universitet, Molekylär fysik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-125726.
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When exposed to light, metal nanoparticles exhibit a phenomenon known as LSPR, Localized Surface Plasmon Resonance. The wavelengths at which LSPR occurs is very dependent on the refractive index of the surrounding medium. Binding of biomolecules to the surface of gold nanoparticles result in a change in the refractive index that can be detected spectrophotometrically by monitoring the LSPR peak shift. When functionalized with the corresponding ligand(s), gold nanoparticles can be utilized in biosensors to detect the presence and concentration of a predetermined analyte. However, the system must exhibit high specificity and give rise to a detectable shift for analytes in the desired concentration range to be of commercial interest. The aim of the diploma project was to investigate and optimize the biofunctionalization and performance of a fiber optics based LSPR biosensor. Three ligand systems were investigated for detection of antibodies (IgG), insulin and avidin. Binding of the analyte to the ligand caused a shift of a few nanometers when using spherical gold nanoparticles. The shifts were significantly larger when using gold nanorods. When using the IgG and insulin ligands, only minor unspecific binding was observed. The setup thus shows great potential for use in a wide range of sensing applications.
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Rugeland, Patrik. "Applications of monolithic fiber interferometers and actively controlled fibers." Doctoral thesis, KTH, Laserfysik, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-118750.
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The objective of this thesis was to develop applications of monolithic fiber devices and actively controlled fibers. A special twin-core fiber known as a ‘Gemini’ fiber was used to construct equal arm-length fiber interferometers, impervious to temperature and mechanical perturbations. A broadband add/drop multiplexer was constructed by inscribing fiber Bragg gratings in the arms of a Gemini Mach-Zehnder interferometer. A broadband interferometric nanosecond switch was constructed from a micro-structured Gemini fiber with incorporated metal electrodes. Additionally, a Michelson fiber interferometer was built from an asymmetric twin-core fiber and used as a high-temperature sensor. While the device could be readily used to measure temperatures below 300 °C, an annealing process was required to extend the range up to 700 °C. The work included development, construction and evaluation of the components along with numerical simulations to estimate their behaviors and to understand the underlying processes. The thesis also explored the use of electrically controlled fibers for filtering in the microwave domain. An ultra-narrow phase-shifted fiber Bragg grating inscribed in a fiber with internal electrodes was used as a scanning filter to measure modulation frequencies applied to an optical carrier. A similar grating was used inside a dual-wavelength fiber laser cavity, to generated tunable microwave beat frequencies. The studied monolithic fiber interferometers and actively controlled fibers provide excellent building blocks in such varied field as in microwave photonics, telecommunications, sensors, and high-speed switching, and will allow for further applications in the future.Syftet med denna avhandling var att utveckla tillämpningar av monolitiska fiber komponenter samt aktivt kontrollerbara fiber. En speciell tvillingkärnefiber, även kallad ’Geminifiber’ användes för att konstruera fiber interferometrar med identisk armlängd som ej påverkas av termiska och mekaniska variationer. En bredbanding utbytarmultiplexor konstruerades genom att skriva in fiber Bragg gitter inuti grenarna på en Gemini Mach-Zehnder interferometer. Geminifibrer med interna metallelektroder användes för att konstruera en bredbandig nanosekundsnabb interferometrisk fiberomkopplare. Därtill användes en tvillingkärnefiber som en hög-temperatursensor. Även om komponenten direkt kan användas upp till 300 °C, måste den värmebehandlas för att kunna användas upp till 700 °C. Arbetet har innefattat utveckling, konstruktion och utvärdering av komponenterna parallellt med numeriska simuleringar för att analysera deras beteenden samt få insikt om de underliggande fysikaliska processerna. Avhandlingen behandlar även tillämpningar av en elektriskt styrbar fiber för att filtrera radiofrekvenser. Ett ultrasmalt fasskiftat fiber Bragg gitter skrevs in i en fiber med interna elektroder och användes som ett svepande filter för att mäta modulationsfrekvensen på en optisk bärfrekvens. Ett liknande gitter användes inuti en laserkavitet för att generera två olika våglängder samtidigt. Dessa två våglängder användes sedan för att generera en svävningsfrekvens i mikrovågsbandet. De undersökta monolitiska fiberinterferometrarna och de aktivt styrbara fibrerna erbjuder en utmärkt byggsten inom så pass skiljda områden som Mikrovågsfotonik, Telekommunikation, Sensorer samt Höghastighets-omkopplare och bör kunna användas inom många olika tillämpningar i framtiden.
QC 20130226
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Xiao, Hai. "Self-Calibrated Interferometric/Intensity-Based Fiber Optic Pressure Sensors." Diss., Virginia Tech, 2000. http://hdl.handle.net/10919/28845.
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To fulfill the objective of providing robust and reliable fiber optic pressure sensors capable of operating in harsh environments, this dissertation presents the detailed research work on the design, modeling, implementation, analysis, and performance evaluation of the novel fiber optic self-calibrated interferometric/intensity-based (SCIIB) pressure sensor system.
By self-referencing its two channels outputs, for the first time to our knowledge, the developed SCIIB technology can fully compensate for the fluctuation of source power and the variations of fiber losses. Based on the SCIIB principle, both multimode and single-mode fiber-based SCIIB sensor systems were designed and successfully implemented. To achieve all the potential advantages of the SCIIB technology, the novel controlled thermal bonding method was proposed, designed, and developed to fabricate high performance fiber optic Fabry-Perot sensor probes with excellent mechanical strength and temperature stability. Mathematical models of the sensor in response to the pressure and temperature are studied to provide a guideline for optimal design of the sensor probe. The solid and detailed noise analysis is also presented to provide a better understanding of the performance limitation of the SCIIB system. Based on the system noise analysis results, optimization measures are proposed to improve the system performance. Extensive experiments have also been conducted to systematically evaluate the performance of the instrumentation systems and the sensor probes. The major test results give us the confidence to believe that the development of the fiber optic SCIIB pressure sensor system provides a reliable pressure measurement tool capable of operating in high pressure, high temperature harsh environments.Ph. D.
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Juarez, Juan C. "Distributed fiber optic intrusion sensor system for monitoring long perimeters." Thesis, [College Station, Tex. : Texas A&M University, 2005. http://hdl.handle.net/1969.1/ETD-TAMU-1702.
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Kunzler, Wesley Mont. "Fiber Optic Sensor Interrogation Advancements for Research and Industrial Use." BYU ScholarsArchive, 2011. https://scholarsarchive.byu.edu/etd/2608.
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Spectrally-based fiber optic sensors are a rapidly maturing technology capable of sensing several environmental parameters in environments that are unfitting to electrical sensors. However, the sensor interrogation systems for this type of sensors are not yet fit to replace conventional sensor systems. They lack the speed, compact size, and usability necessary to move into mainstream test and measurement. The Fiber Sensor Integrated Monitor (FSIM) technology leverages rapid optical components and parallel hardware architecture to move these sensors across the research threshold into greater mainstream use. By dramatically increasing speed, shrinking size, and targeting an interface that can be used in large-scale industrial interrogation systems, spectrally-based fiber optic sensors can now find more widespread use in both research labs and industrial applications. The technology developed in this thesis was demonstrated by producing two advanced interrogators: one that was one half the size of commercially available systems, and one that accelerated live spectral capture by one thousand times – both of which were operated by non-developers with little training.
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Holmberg, Patrik. "Laser processing of Silica based glass." Doctoral thesis, KTH, Laserfysik, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-173929.
Full textAbstract:
The main topic of this thesis work is photosensitivity and photo-structuring of optical fibers and bulk glass. Although research in the field of photosensitivity in glass and optical fibers has been ongoing for more than three decades, the underlying mechanisms are still not well understood. The objective was to gain a better understanding of the photo-response by studying photosensitivity from a thermodynamic perspective, as opposed to established research focusing on point defects and structural changes, and strain and stress in optical fibers. Optical fibers was mainly used for experimental studies for two reasons; first, photosensitivity in fibers is more pronounced and more elusive compared to its bulk counterpart, and secondly, fibers provide a simplified structure to study as they experimentally can be seen as one-dimensional.Initially, ablation experiments on bulk glass were performed using picosecond infrared pulses. With a design cross section of 40x40 μm, straight channels were fabricated on the top (facing incident light) and bottom side of the sample and the resulting geometries were analyzed. The results show a higher sensitivity to experimental parameters for bottom side ablation which was ascribed to material incubation effects. Moreover, on the top side, the resulting geometry has a V-shape, independent of experimental parameters, related to the numerical aperture of the focusing lens, which was ascribed to shadowing effects.After this work, the focus shifted towards optical fibers, UV-induced fiber Bragg gratings (FBGs) and thermal processing with conventional oven and with a CO2 laser as a source of radiant heat.First, a system for CO2 laser heating of optical fibers was constructed. For measuring the temperature of the processed fibers, a special type of FBG with high temperature stability, referred to as "Chemical Composition Grating" (CCG) was used. A thorough characterization and temperature calibration was performed and the results show the temperature dynamics with a temporal resolution of less than one millisecond. The temperature profile of the fiber and the laser beam intensity profile could be measured with a spatial resolution limited by the grating length and diameter of the fiber. Temperatures as high as ~ 1750 °C could be measured with corresponding heating and cooling rates of 10.500 K/s and 6.500 K/s.Subsequently, a thorough investigation of annealing and thermal regeneration of FBGs in standard telecommunication fibers was performed. The results show that thermal grating regeneration involves several mechanisms. For strong regeneration, an optimum annealing temperature near 900 C was found. Two different activation energies could be extracted from an Arrhenius of index modulation and Braggv iwavelength, having a crossing point also around 900 °C, indication a balance of two opposing mechanisms.Finally, the thermal dynamics and spectral evolution during formation of long period fiber gratings (LPGs) were investigated. The gratings were fabricated using the CO2 laser system by periodically grooving the fibers by thermal ablation. Transmission losses were reduced by carefully selecting the proper processing conditions. These parameters were identified by mapping groove depth and transmission loss to laser intensity and exposure time.Huvudtemana i denna avhandling är fotokänslighet och fotostrukturering av optiska fibrer och bulk glas. Trots att forskning inom fotokänslighet i glas och optiska fibrer har pågått under mer än tre decennier är de bakomliggande mekanismerna ännu inte klarlagda. Syftet var att få en bättre förståelse för fotoresponsen genom att studera fotokäsligheten ur ett termodynamiskt perspektiv, i motsats till etablerad forskning med fokus på punktdefekter och strukturförändringar, samt mekaniska spännings effekter i optiska fibrer. Optiska fibrer användes för flertalet av de experimentella studierna av två skäl; för det första är fotokänsligheten i fibrer större och dessutom vet man mindre om bakomliggande mekanismer jämfört med motsvarande bulk glas, och för det andra kan fibrer vara enklare att studera eftersom de experimentellt kan ses som en endimensionell struktur.Inledningsvis utfördes ablaherings experiment på bulk glas med en infraröd laser med pikosekund pulser. Raka kanaler med ett designtvärsnitt på 40x40 μm tillverkades på ovansidan (mot infallande ljus) och bottensidan av provet och de resulterande geometrierna analyserades. Resultaten visar en högre känslighet för variationer i experimentella parametrar vid ablahering på undersidan vilket kan förklaras av inkubations effekter i materialet. Dessutom är den resulterande geometrin på ovansidan V-formad, oavsett experimentella parametrar, vilket kunde relateras till den numeriska aperturen hos den fokuserande linsen, vilket förklaras av skuggningseffekter.Efter detta arbete flyttades fokus mot optiska fibrer, UV inducerade fiber Bragg gitter (FBG), och termisk bearbetning med konventionell ugn samt även med en CO2-laser som källa för strålningsvärme.Först konstruerades ett system för CO2-laservärmning av fibrer. För mätning av temperaturen hos bearbetade fibrer användes en speciell sorts FBG med hög temperaturstabilitet, kallade ”Chemical Composition Gratings” (CCG). En grundlig karaktärisering och temperaturkalibrering utfördes och temperaturdynamiken mättes med en tidsupplösning på under en millisekund. Temperaturprofilen i fibern, och laserns strålprofil, kunde mätas med en spatiell upplösning begränsad av gitterlängden och fiberns diameter. Temperaturer upp till ~1750 °C, vilket är högre än mjukpunktstemperaturen, kunde mätas med korresponderande uppvärmnings- och avsvalningshastighet på 10.500 K/s och 6.500 K/s.Därefter gjordes en omfattande undersökning av värmebearbetning och termisk regenerering av FBG:er i telekomfiber. Resultaten visar att termisk gitter-regenerering aktiveras av flera olika mekanismer. Värmebearbetning vid en temperatur omkring 900 °C resulterade i starka gitter efter en regenerering vid en temperatur på 1100 °C. Två olika aktiveringsenergier kunde extraheras från en Arrhenius plot avseende brytningsindexmodulation och Braggvåglängd, med en skärningspunkt tillika runt 900 °C, vilket indikerar en avvägning mellan två motverkande mekanismer vid denna temperatur.Slutligen undersöktes temperaturdynamiken och de spektrala egenskaperna under tillverkning av långperiodiga fibergitter (LPG). Gittren tillverkades med CO2-vi iilasersystemet genom att skapa en periodisk urgröpning medelst termisk ablahering. Transmissionsförluster kunde reduceras med noggrant valda processparametrar. Dessa parametrar identifierades genom mätningar av ablaherat djup och transmissionsförlust som funktion av laserintensitet och exponeringstid.
QC 20150924
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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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Su, Xu. "Design and Evaluation of Off-centered Core Fiber for Gas Sensing." Thesis, Virginia Tech, 2020. http://hdl.handle.net/10919/99348.
Full textAbstract:
Gas Sensing Has Become a Very Important and Attractive Technique Because of Its Various Applications, Such as in the Increasingly Concerning Case of Environmental Issues, Automobile Emission Detection, Natural Gas Leakage Detection, Etc. It Also Has Significant Applications in Industries, Such as Safety and Health Monitoring in Underground Mines. Among Those Sensing Areas, Fiber-optic Sensors Have Drawn Considerable Attention Because of Its Small Size, Light Weight, High Sensitivity, and Remote Sensing Capability. However, Current Fiber-optic Gas Sensing Techniques Have Several Limitations on Their Potential for Multiplexed or Distributed Sensing Due to Difficulties Such as High Complexity or Large Loss.
To Accomplish the Goal for Multiplexed Gas Sensing, an Off-centered Core Fiber Design Is Investigated. The Eccentric Core Can Reduce Attenuation, Keep Mechanical Strength, and Lower Fabrication Cost. To Verify the Feasibility of the Design, Fiber Field Distribution Is First Studied in Simulation, Which Will Be Discussed in Detail in Chapter 2. Then Two Fiber Samples with a Length of 10 Cm and 40 Cm Are Prepared and Placed in a Custom Methane Sensing System for Gas Absorption Testing, Which Is Detailed in Chapter 3. From Etching Analysis, Localized Surface Defects Are Found as the Main Reason for Power Loss. Performance Such as Detection Resolution and Sensitivity Are Investigated. In Chapter 4, Theoretical Evaluations Have Been Conducted for Multiplexed Sensors Performances Using the Off-centered Core Fiber to Study the Impact Fiber Parameters on Sensing System Design. The Conclusion and Summary Are Presented in Chapter 5.Master of Science
Gas Sensing Has Become a Very Important and Attractive Technique Because of Its Various Applications, Such as in the Increasingly Concerning Case of Environmental Issues, Automobile Emission Detection, Natural Gas Leakage Detection, Etc. It Also Has Significant Applications in Industries, Such as Safety and Health Monitoring in Underground Mines. Among Those Sensing Areas, Fiber-optic Sensors Have Drawn Considerable Attention Because of Its Small Size, Light Weight, High Sensitivity, and Remote Sensing Capability. However, Current Fiber-optic Gas Sensing Techniques Have Several Limitations on Their Potential for Long Distance Distributed Sensing Due to Difficulties Such as High Fabrication Complexity. In This Work, a Fiber-optic Gas Sensor with Special Structure Was Designed. The Sensor Can Reduce Attenuation, Keep Mechanical Strength, and Lower Fabrication Cost. To Verify the Feasibility of the Design, Theory Analysis and Simulation Were Conducted, Which Will Be Discussed in Detail in Chapter 2. Then Two Samples with a Length of 10 Cm and 40 Cm Were Prepared and Placed in a Custom Methane Sensing System for Testing. And Their Performance Such as Sensitivity Is Investigated. In Chapter 4, Theoretical Evaluations Have Been Conducted for Multiplexed Sensors Performances Evaluation to Study the Impact Fiber Parameters on Sensing System Design. The Conclusion and Summary Are Presented in Chapter 5.
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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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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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CHIANG, CHIA-CHI, and 江嘉琪. "Multimode Tapered Fiber Sensor." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/23264534191282230961.
Full textAbstract:
碩士國立中正大學
物理學系暨研究所
100
In this thesis, fabrication of a multimode tapered fiber is presented. The coating and cladding of the fiber was first removed by using the CO2 laser. Afterward, while heating the uncladded fiber with the Bunsen burner, a tapered fiber was made by pulling the fiber to a desired length by a translational stage. The ability of the fabricated tapered fiber to detect the refractive index (RI) of surrounding media is investigated. It is found that the RI sensitivity of this type of tapered fiber increased with the decreasing of waist diameter of the tapered fiber. Further modification of the tapered fiber with colloidal gold nanoparticles show that the RI sensitivity can be enhanced based on the mechanism of localized surface plasma resonance.
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Chiu, Chih-Hung, and 邱志鴻. "Fiber grating tilt sensor." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/54464845313846271843.
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碩士逢甲大學
電機工程所
99
A tilt sensor mainly composed of long period fiber grating is proposed. The long period grating (LPG) is glued by a plate with slot. The plate make the LPG be suspended and is fixed inside a container. The container is filled with some liquid until half-length of LPG is immersed. When the tilt sensor is inclined, the liquid depth will be changed because of the flowing liquid. The different immersed lengths of LPG result to the transmission power changing. Then we can read the value transmission power to estimate the tilt angle. The normal tilt sensors usually have ability to measure precisely, but can’t be applied to large range of tilt angle. Otherwise, if the tilt sensors can be applied to large range of tilt angle, it just can measure roughly. This dissertation proposes a tilt sensor not only can measure precisely, but also can be applied to large range of tilt angle. So, the tilt sensor will be used in much more field.
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Kuruba, Nithin Shekar. "Hollow fiber coupler sensor." Thesis, 2018. https://dspace.library.uvic.ca//handle/1828/10404.
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This thesis presents a method to fabricate a robust optical directional coupler sensor using a solid core fiber (SCF) and a hollow core fiber (HCF). Through
evanescent wave coupling mechanism, the optical power is exchanged between SCF
and HCF. The hollow core of the HCF can be filled with liquid samples to alter the
coupling ratio which imparts change in amount of light propagating through the SCF.
Thus, it gives the coupler with ability of sensing refractive index of the sample with
good sensitivity of 4.03 ± 0.50 volts per refractive index units (V/RIU) for refractive
indices ranging from 1.331 ± 0.003 to 1.403 ± 0.003 with a resolution of 3.5 × 10−3
refractive index units (RIU). The SCF-HCF coupler was also used to sense the temperature based on the concept of temperature dependence on refractive index of the
sample inside the hollow core of HCF. Further, the packaging methods are described
that protect coupler from ambient environments and improves the life span of sensor.Graduate
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Yu-lin, Fang, and 方友霖. "Polarization optical fiber sensor." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/k5r32j.
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博士國立高雄科技大學
機械工程系
107
This study proposes a multi-functional lab and used the principles of polarization light, long period fiber grating (LPFG) along with inductive couple plasma-Etcher to develop a POL-NLPFG lab on fiber sensor for strain. Using the POL-NLPFG sensors to detect the variations of the longitudinal loading. According to the results of the experiments, finding that the longitudinal loading are strengthen, the phenomenon of the transmission loss agrees with the coupled-mode theory and the dips of transmission loss performance a function of cosine. The sensor that execute the experiment of the axial loading test for more times to ensure the feasibility and reproducibility of the proposed optical fiber sensors. An Polarization u-shaped optical sensor that used alkylation technology to immobilize MiRNA-133a had be used to detect Mahlavu at concentrations 0.133 ng/ml-0.064 ng/ml was added to test the sensor. The results showed that the highest Mahlavu sensitivity of the Polarization U-shaped optical sensor spectral wavelength was-633.94 nm/% and linearity was 0.998. The results of the experiments indicated that the Polarization U-shaped optical sensor refractive index changed as Mahlavu concentrations increased, altering the coupling coefficient and causing linear changes in wavelength or transmission loss. These experiments verified that the Polarization U-shaped sensors developed in this study can be used as multi-functional lab on fiber sensing elements.
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"Some applications of optical fibre sensor." Chinese University of Hong Kong, 1989. http://library.cuhk.edu.hk/record=b5886613.
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CHEN, JUN-YI, and 陳俊逸. "Improved Optical Fiber pH Sensor." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/pyzzk5.
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碩士銘傳大學
電子工程學系碩士班
104
PH value is used to specify the acidity or basicity of an aqueous solution because many biological and chemical reactions depend on suitable pH value. PH sensors are widely used in chemical plants, laboratories and hospitals, so a fiber optic pH sensor is proposed to measure the pH value of an aqueous solution. With the help of an acid-base indicator, an aqueous solution with different pH value has different absorption of light. Detecting the optical power of an aqueous solution, the pH value can be assessed. However, according to previous researches, the measurement range of pH value is limited just by using one acid-base indicator. The paper further proposed an improved method by using two more mixed acid-base indicators to enlarge measurement range of pH value. A mixed indicator of a methyl orange indicator and a phenol red indicator is successfully used to verify the research, while the wavelength of detecting light is 522 nm. The change in pH value is 8.22 nW / pH within pH 1~7.
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Guo, Jia-hao, and 郭家豪. "Microfluidics for Fiber-sensor Application." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/84663206057135502240.
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碩士國立成功大學
光電科學與工程研究所
97
In this dissertation, a fiber-base sensor integrated in a microfluidic system is investigated. The fiber sensor is able to detect the refractive index change at the exposed fiber core created by a time-controlled HF etch of the fiber. Effects of the etch time and exposed length to the sensitivity are also studied. The fiber sensor is also modified by covalent bonding of colloid gold nanoparticles to the exposed fiber core surface. The strong localized surface plasmon resonance scattering from the gold nanoparticles is able to enhance the sensitivity of the fiber sensor when the resonant green laser light is used. In addition, a microfluidic channel system is also developed to minimize the cost of the precious material that this system is design to detect. The microfluidic is made from using PDMS as the fabrication materials. Microfluidic channels with tens of micrometers in height and hundreds of micrometers in width are successfully fabricated. A syringe pump system that can pump the fluid into the system is able developed. Several fabrication parameters are also investigated to understand the performance of the microfluidic system. In conclusion, a plasmon-enhanced fiber sensor integrated in a microfluidic system is investigated. Further detailed studies of this system will be beneficial for future bio-sensing application.
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Lin, Ming Ching, and 林銘清. "Application of Optical Fiber Amplifier For Fiber Sensor and Fiber Ring Laser." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/81156727069054242645.
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碩士國立交通大學
光電工程系所
93
In the first part of the thesis, we propose and investigate experimentally a gain-clamped S-band erbium-doped fiber amplifier (EDFA), a stable and single-longitudinal-mode oscillation of an S-band EDF ring laser. The behaviors and performances of the S-band amplifier have also been discussed in the text. Single-longitudinal-mode laser output can be realized by employing a Fabry-Perot filter and a saturable-absorber-based autotracking filter composed of an unpumped EDF and an optical reflector. The performance of output power is larger then 10 dBm and a side-mode suppression ratio (SMSR) is larger then 49.1 dB from 1488.7 to 1505.7 nm. In the second part of the thesis, we propose the S-band fiber sensor technique and a multiplexed fiber sensing system based on semiconductor optical amplifier (SOA). In the experiment of S-band fiber sensor system, the proposed laser lases at each wavelength of the FBG accordingly by tuning the Fabry-Perot filter. In the experiment of multiplexed sensing system, all lasing wavelengths based on the inhomogeneous broadening effect of SOA are accordingly the FBG central wavelength. Using properly coupling ratio, we can obtain the clearly optical signals.
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Guru, Prasad A. S. "Fiber Bragg Grating Sensors : An Exploration Of Applications In Diverse Fields." Thesis, 2012. http://etd.iisc.ernet.in/handle/2005/2507.
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Sensors have become essential elements in human life for safe and comfortable existence in the ever demanding world. Various technologies over decades have contributed in their own way fulfilling innumerable sensing requirements. The discovery of optical sensor technologies has revolutionized the sensing field due to their inherent advantages. Among the large number of fiber optic sensor technologies, FBG based sensors have become widely known and popular within and outside the photonics community and has seen a prominent rise in their utilization.
This thesis explores the use of FBG sensors for a wide range of applications scanning across a variety of engineering and medical applications, in the areas of civil engineering, biomechanical engineering, aerospace engineering, geoengineering, etc. It also deals with newer methods of packaging FBG sensors for the measurement of specific engineering parameters like strain, temperature, pressure, displacement and vibration.
In the field of civil engineering, FBG sensors are employed for strain sensing on a prism and furthermore tested on a full size brick wallet. During this study, emphasis is made on substituting traditional sensors by specially packaged FBG sensors with the intent of either enhancing the sensing system’s performance or in merging/uniting the inherent advantages of FBG sensors.
In the area of biomechanics, a novel sensor methodology using FBG sensors, for measuring surface strains generated on the skin of the calf muscle during various leg exercises is proposed. This methodology is used to address one of the most critical and life threatening issues in long distance air travel, namely the Deep Vein Thrombosis. Further, a FBG sensor based plantar sensing plate, is designed and developed, to measure plantar strain distribution in foot and also to analyze the postural stability.
In the field of aerospace engineering, FBG sensors are used for addressing two of the most vital issues; Structural Health Monitoring (SHM) and direct measurement of pressure and temperature on the surface of an aircraft under hypersonic wind flow. Carbon Fiber Composite coupon level testing is carried out to obtain a generic strain calibration factor for the FBG sensor. Further, FBG sensors are exploited for the direct measurement of absolute temperature and pressure on the leeward surface of blunt cone at hypersonic wind speeds.
In the domain of geoengineering, the feasibility studies have been undertaken to use a FBG as a seismic sensor and as a bore-well characterizing sensor. A novel FBG seismic sensor package is developed using a single FBG sensor to pick up the seismic waves propagating through the ground generated from earthquakes and ground tremors. Further, FBG sensors are used for measurement of temperature profiles in a bore-well to delineate and characterize the behavior of fractures during seasonal climatic changes. To summarize, the present thesis demonstrates a comprehensive experimental study which bring out the utility of FBG sensors in a variety of challenging applications.
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Huang, Jia-Ying, and 黃嘉瑩. "Optical Fiber Immuno-sensor based on Long Period Fiber Grating." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/63007982310996093057.
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碩士國立高雄應用科技大學
機械與精密工程研究所
101
In this thesis, the Sandwiched long period fiber grating (SLPFG) and Box-shape long period fiber grating (Box-shape LPFG) were fabricated by thick photoresist stacking technique with SU-8 and etching process in Photolithography as the immuno-sensor. The fabrication makes SLPFG and Box-shape LPFG to obtain LPFG function effectively. First to silanition, the LPFG was immersed in NaOH solution and (3-Aminopropyl)triethoxys (APTES) solution to generate O-H bond and N-H bond on the surface of optical fiber for binding biomolecule. The spectrum were varied strongly when O-H bond binding N-H bond. For SLPFG, the resonant wavelength shift was 18.232nm, the transmission loss increased -2.31dB, and for Box-shape LPFG, the resonant wavelength shift was 0.999nm, and the transmission loss increased -2.66dB. Second to analyze the resonant wavelength and transmission loss for SLPFG and Box-shape LPFG that HDAC6 binding specificity secondary antibodies horseradish peroxidase on the surface of immune-sensors. For SLPFG, the resonant wavelength shift was 15.984nm and the transmission loss increased -12.73dB. For Box-shape LPFG, the resonant wavelength shift was 11.98nm and the transmission loss increased -7.6dB. For separating the cell membranes and impurities, the Mahlavu and SK-Hep1 cells were transferred with expression plasmids and the extraction were drew to the 1.5mL tube As the result shown in Mahlavu, the resonant wavelength shits were steady and transmission loss were -0.22dB. For SK-Hep1 cells, the resonant wavelength shits were 24.27nm and transmission loss were -8.92dB. In conclusion, this immuno-sensor for detecting specific protein for HDAC6 is workable.
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Hsu, Rong-chen, and 徐榕辰. "Fiber Strain Sensor Study and Research." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/07841932261630801344.
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碩士國立臺灣科技大學
電子工程系
100
In this thesis, we investigated, designed and analyzed the fiber sensing systems for microstrain applications. A super-luminescent diode (SLED), which had a maximum output at 1550-nm wavelength, involved with a 1.3-?慆 wavelength distributed feedback laser as the optical ruler and propagated through optical low coherence interferometer (OLCI), where the fiber was installed in one of two arms followed by a scheme of the wavelength division multiplexer (WDM) couplers, photo-detection, and electric noise filtering. A Mach-Zehnder interferometer (MZI) built with the SMF-28 fiber sensing arm was demonstrating the strain sensitivity up to , and we proposed a cascaded MZI, it could improve the sensitivity of the system and decrease the insertion loss by the optical coupler. The strain sensitivity up to . The traditional fiber Bragg grating (FBG) was then utilized to show the resonance wavelength caused by the stress parameter using the grating strain effect. The sensitivity could achieve . Finally we put the two fiber sensors, SMF-28 fiber and FBG, together for strain monitoring applications. Moreover, the contra-directional narrow linewidth spectrum from FBG was simultaneously utilized as the optical ruler for the cascaded MZI OLCI, which can significantly reduce the cost by eliminating the WDM couplers for traditional optical ruler system. We successfully demonstrated the strain monitoring system for large and small scales by cascaded MZI OLCI with the FBG contra-directional spectrum optical ruler.
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吳名堃. "Curing Analysis of Glass Fiber Composites by Embedded Optical Fiber Sensor." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/3825yc.
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Liao, Chein-Ming, and 廖建銘. "Study of Long Period Fiber of Photonic Crystal Fiber Grating Sensor." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/75188492217612791272.
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碩士國立中正大學
物理所
96
In this thesis, long-period gratings (LPGs) and all-fiber interferometer in three different types of photonic crystal fibers (PCFs), ESM-12-01, LMA-10, and PM1550, were fabricated by using the electric-arc technique. The influence of refractive index and strain to these two optical fiber devices are investigated. Among the three different PCFs, we found that refractive index sensing with LMA-10 gratings was quite sensitive (107.14nm/RIU) and its resonance wavelength was red shifted with increasing refractive index. For strain measurement with ESM-12-01, interferometer (0.002395 nm/με) exhibited better sensitivity than that of grating (0.001344 nm/με) and the wavelength was found to blue shift with increasing strain. Resonance wavelength of PM1550 gratings were found to blue shift with the increasing of gratings period.