Dissertations / Theses: 'Optical fiber detectors'

1

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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2

Nagarajan, Anjana. "Chemical sensing applications of fiber optics." Thesis, This resource online, 1994. http://scholar.lib.vt.edu/theses/available/etd-07102009-040555/.

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3

Haskell, Adam Benjamin. "A Durability and Utility Analysis of EFPI Fiber Optic Strain Sensors Embedded in Composite Materials for Structural Health Monitoring." Fogler Library, University of Maine, 2006. http://www.library.umaine.edu/theses/pdf/HaskellAB2006.pdf.

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4

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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5

Kinney, Stuart. "The development of an optical position sensor." Virtual Press, 1998. http://liblink.bsu.edu/uhtbin/catkey/1115421.

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A theoretical study of an electrically passive, loss-compensated, optical position sensor is the goal of this project. Optical fiber sensors exploit light as the information carrier. Fiber-optic sensors consist of a constant light source launched into an optical fiber and transmitted to another point at which a measurement is made.In the proposed optical position sensor, a Light Emitting Diode (LED) produces a constant beam of light, which is channeled through an optical fiber to a Graded Index (GRIN) lens. This lens makes all the light rays parallel to one another, a process called collimation. The light then enters a polarizer which is a lens that further orders the light rays in a process called polarization.Then the light enters a chamber in which a doubly refracting (birefringent) crystal is situated. The crystal is a wedge, and thus has a varying thickness throughout its length. The light beam strikes the crystal, sending a spectrum, or spectral signature, that is distinct to the particular thickness of the crystal. That signature goes directly from the chamber housing the crystal into a lens called an analyzer which orders the light again through polarization. Then the light goes into another GRIN lens, and this GRIN lens focuses the light onto an optical fiber, which transmits the particular spectral signature of this light to an optical spectrum analyzer (OSA). The OSA uses a Photodiode Array to accept the incoming light, a device that takes in light and redistributes it to a monitor for display by the user. Such a device is called a detector. The thickness of the crystal that the light travels through is determined by the crystal's position.If the crystal rests on a platform which is connected to an object whose position must always be monitored, then the crystal will move as the object moves. The different spectral signatures shown on a monitor reveal different thicknesses of the crystal, which reveal different positions of the monitored object. The object whose position is measured is the measurand.The selected crystal is quartz. It has a 12.5-mm length, a width of 10.8-mm at its thinnest end, and a taper angle to the thickest end of only 0.008 degrees, which corresponds to a 0.17-micron difference between the two. This angle is called the polishing angle of the quartz. The quartz itself is called the active cell. The Photodiode Array Detector receives the spectral signature from the optical fiber, and that signature is projected on an OSA, which is software built-in to the computer. A mathematical program is used to evaluate the signature, and the position of the measurand is thereby revealed. How accurate the measurement is can be revealed by use of a control device. If the quartz crystal is moved by a measuring device, such as a micrometer, the distance that the crystal moved may be measured by the micrometer, as well as by the OSA. By comparing the two, the accuracy of the spectrograph, and the position it reveals, can be known.
Department of Physics and Astronomy

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6

Utou, Frumence E. "Fiber optic sensors ensuring structural integrity." Thesis, Cape Peninsula University of Technology, 2005. http://hdl.handle.net/20.500.11838/1300.

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Thesis (DTech (Mechnical Engineering))--Cape Peninsula University of Technology, 2005
Among the issues that are taken into consideration for many years by Engineers and Technologists is the integrity of the servicing elements in structures and mechanisms. It is a documented phenomenon that after a certain period of time, in service, engineering components tend to change their original state, and begin to develop faults and defects. This includes the original shape distortion due to effects such as bending, twisting, and cracks. The above-sited effects may be caused by the sudden or accumulative effect of overloading, thermal shocks, corrosion etc, which eventually lead to malfunction of these engineering components. The occurrence of the cracks may be as a result of stress variation in excess of different or similar materials; thermal shocks, vibration, etc. A system of structural health monitoring using optical fiber sensors to track down a crack occurrence and its propagation is considered to be a promising method in warning of catastrophic events. Taking advantage of optical fibers' properties and behavior, such as easy interaction with other materials, small size, low weight, corrosion resistance, geometrical flexibility and an inherent immunity to electromagnetic interference, there is potential in adopting the Fiber Optic Sensors (FOS) for structural health monitoring systems. Structural integrity does not confine itself to crack detection only. For example there are many instances where unwanted or excessive displacement may occur. Optical fibers play an important role in proximity sensing as evidenced in the literature [49] to [54] and available commercial systems. However it is felt that FOS displacement sensors may suffer in measurement accuracy due to in situ conditions.

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7

Jong, Yeung-dong. "Fiber-optic interferometer for high 1/f noise environments /." Digital version accessible at:, 1998. http://wwwlib.umi.com/cr/utexas/main.

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8

Shih, Jessica Chu-Huei. "Concentric-core optical fiber sensors." Thesis, Virginia Polytechnic Institute and State University, 1986. http://hdl.handle.net/10919/91069.

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This thesis describes the implementation of a mechanical strain sensor which uses concentric core optical fiber waveguide as the sensing element. When this particular type of fiber is strained, a transfer of optical power occurs between propagating modes in the two concentric cylindrical cores of the fiber. This strain-induced redistribution of optical power may be detected at the output end of the fiber using either two separated optical detectors or a two dimensional detector array. The calibrated strain sensitivity of the sensor is reported and suggestions for continuing research are discussed.
M.S.

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9

Wei, Tao. "Fabrication of long-period fiber gratings by CO₂ laser irradiation for high temperature applications." Diss., Rolla, Mo. : Missouri University of Science and Technology, 2008. http://scholarsmine.mst.edu/thesis/pdf/Wei_09007dcc804a8ac2.pdf.

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Thesis (M.S.)--Missouri University of Science and Technology, 2008.
Vita. The entire thesis text is included in file. Title from title screen of thesis/dissertation PDF file (viewed March 31, 2008) Includes bibliographical references (p. 33-36).

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Miller, Mark S. "Advances in elliptical-core two-mode optical fiber sensors." Thesis, Virginia Tech, 1990. http://hdl.handle.net/10919/41617.

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Methods designed to improve the practicality of the elliptical-core two-mode optical fiber sensors for use in real-life applications are presented. The improvements include the development of insensitive lead fibers and an optical device which allows fringe counting at the output of the sensor. The insensitive leads eliminate extraneous perturbations and effectively isolate the sensing region. The fringe counting optics are designed to generate quadrature-phase shifted signals, thereby allowing the determination of whether the strain is increasing or decreasing. Work performed to advance the understanding of the effect of sensor placement within a composite specimen is also presented. Optical fiber sensors are embedded between different laminae of a graphite-epoxy composite panel, and the outputs of the sensors are shown to be proportional to the distance of the sensor from the neutral axis.
Master of Science

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11

Xu, Xingyuan. "Improving the performance of FBG sensing system." Access electronically, 2006. http://www.library.uow.edu.au/adt-NWU/public/adt-NWU20070110.144936/index.html.

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12

Ferguson, Jane A. "Fiber optic chemical sensors : the evolution of high-density fiber-optic DNA microarrays /." Thesis, Connect to Dissertations & Theses @ Tufts University, 2001.

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Thesis (Ph.D.)--Tufts University, 2001.
Adviser: David R. Walt. Submitted to the Dept. of Chemistry, Includes bibliographical references (leaves 197-208). Access restricted to members of the Tufts University community. Also available via the World Wide Web;

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13

Silva, Muñoz Rodrigo. "Structural Health Monitoring Using Embedded Fiber Optic Strain Sensors." Fogler Library, University of Maine, 2008. http://www.library.umaine.edu/theses/pdf/SilvaMunozR2008.pdf.

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14

Murphy, Kent A. "Novel phase-modulated optical fiber sensors." Diss., Virginia Tech, 1992. http://hdl.handle.net/10919/39712.

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15

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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16

Beadle, Brad Michael. "Fiber optic sensor for ultrasound." Thesis, Georgia Institute of Technology, 1999. http://hdl.handle.net/1853/19173.

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17

K, C. Ravikumar. "Spread spectrum techniques for distributed multimeasurand optical fiber sensors /." This resource online, 1993. http://scholar.lib.vt.edu/theses/available/etd-03142009-040658/.

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18

Shute, Marcus William Sr. "Polarization-maintaining optical fiber as a sensor of shell vibrations." Diss., Georgia Institute of Technology, 1994. http://hdl.handle.net/1853/17915.

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19

Hutsel, Michael R. "Characterization of the stress and refractive-index distributions in optical fibers and fiber-based devices." Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/42926.

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Optical fiber technology continues to advance rapidly as a result of the increasing demands on communication systems and the expanding use of fiber-based sensing. New optical fiber types and fiber-based communications components are required to permit higher data rates, an increased number of channels, and more flexible installation requirements. Fiber-based sensors are continually being developed for a broad range of sensing applications, including environmental, medical, structural, industrial, and military. As optical fibers and fiber-based devices continue to advance, the need to understand their fundamental physical properties increases. The residual-stress distribution (RSD) and the refractive-index distribution (RID) play fundamental roles in the operation and performance of optical fibers. Custom RIDs are used to tailor the transmission properties of fibers used for long-distance transmission and to enable fiber-based devices such as long-period fiber gratings (LPFGs). The introduction and modification of RSDs enable specialty fibers, such as polarization-maintaining fiber, and contribute to the operation of fiber-based devices. Furthermore, the RSD and the RID are inherently linked through the photoelastic effect. Therefore, both the RSD and the RID need to be characterized because these fundamental properties are coupled and affect the fabrication, operation, and performance of fibers and fiber-based devices. To characterize effectively the physical properties of optical fibers, the RSD and the RID must be measured without perturbing or destroying the optical fiber. Furthermore, the techniques used must not be limited in detecting small variations and asymmetries in all directions through the fiber. Finally, the RSD and the RID must be characterized concurrently without moving the fiber to enable the analysis of the relationship between the RSD and the RID. Although many techniques exist for characterizing the residual stress and the refractive index in optical fibers, there is no existing methodology that meets all of these requirements. Therefore, the primary objective of the research presented in this thesis was to provide a methodology that is capable of characterizing concurrently the three-dimensional RSD and RID in optical fibers and fiber-based devices. This research represents a detailed study of the requirements for characterizing optical fibers and how these requirements are met through appropriate data analysis and experimental apparatus design and implementation. To validate the developed methodology, the secondary objective of this research was to characterize both unperturbed and modified optical fibers. The RSD and the RID were measured in a standard telecommunications-grade optical fiber, Corning SMF-28. The effects of cleaving this fiber were also analyzed and the longitudinal variations that result from cleaving were explored for the first time. The fabrication of carbon-dioxide-laser-induced LPFGs was also examined. These devices provide many of the functionalities required for fiber-based communications components as well as fiber-based sensors, and they offer relaxed fabrication requirements when compared to LPFGs fabricated by other methods. The developed methodology was used to perform the first measurements of the changes that occur in the RSD and the RID during LPFG fabrication. The analysis of these measurements ties together many of the existing theories of carbon-dioxide-laser-induced LPFG fabrication to present a more coherent understanding of the processes that occur. In addition, new evidence provides detailed information on the functional form of the RSD and the RID in LPFGs. This information is crucial for the modeling of LPFG behavior, for the design of LPFGs for specific applications, for the tailoring of fabrication parameters to meet design requirements, and for understanding the limitations of LPFG fabrication in commercial optical fibers. Future areas of research concerning the improvement of the developed methodology, the need to characterize other fibers and fiber-based devices, and the characterization of carbon-dioxide-laser-induced LPFGs are identified and discussed.

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20

Poland, Stephan H. "Applications of optical fiber sensors with thick metal coatings." Thesis, This resource online, 1994. http://scholar.lib.vt.edu/theses/available/etd-06232009-063456/.

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21

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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22

Michael, Karri L. "Development of high-density optical fiber arrays : new designs and applications in microscopy, microfabrication and chemical sensing /." Thesis, Connect to Dissertations & Theses @ Tufts University, 1999.

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Thesis (Ph.D.)--Tufts University, 1999.
Adviser: David R. Walt. Submitted to the Dept. of Chemistry. Includes bibliographical references (leaves 233-253). Access restricted to members of the Tufts University community. Also available via the World Wide Web;

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23

Nau, Gregory Merrill. "Optical fiber detection of ultrasonic vibration and acoustic emission." Thesis, This resource online, 1992. http://scholar.lib.vt.edu/theses/available/etd-09292009-020053/.

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24

Kahn, Mohammed Tariq Ekeramodien. "Development of a non-monochromatic lightwave sensor for applications in smart structures research." Thesis, Peninsula Technikon, 1998. http://hdl.handle.net/20.500.11838/888.

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Thesis (MTech (Electrical Engineering))--Peninsula Technikon, Cape Town, 1998
The purpose of this study was to perform an investigation into advances in the field of opto-electronics and to develop a suitable lightwave sensor, for application in smart structures research. Included in the scope of this research was the theoretical development and analysis of an appropriate technology to lead to an implementation of such sensors. This project forms part of an overall plan to gain experience in optoelectronic (photonic) sensor design. In research done previously in smart structure monitoring, piezo-electric techniques with the usual electrical interconnections was used. In a highly distributed sensor system the problems of electromagnetic interference, the tribo-electric effect and noise could be problematic. In this research, opto electronic techniques were thoroughly researched and an improvement on laser based fibre-optic interferometers was made. A non monochromatic lightwave interferometer was developed from theory and a prototype tested. The results suggests that an interferometric sensor can be operated with a non monochromatic source by using a second interferometer to modulate the frequency spectrum of the light before it is detected by a photodetector. Various test and measurement circuits for improved photodetector performance were evaluated, as well as a study of signal processing techniques that would be of use for an upgrade of the project where specific feature detection and analysis using the sensor is envisaged. A specification for a computer based data acquisition system was developed to do initial tests. The project should continue, with the sensor head being improved and all the necessary signal processing routines programmed into a Labview based data acquisition system.

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25

Kahn, Mohammed Tariq Ekeramodien. "Miniaturised dedicated application opto-electronic sensors in the evolution of smart systems." Thesis, Peninsula Technikon, 2002. http://hdl.handle.net/20.500.11838/1196.

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Thesis (DTech (Electrical Engineering))--Peninsula Technikon, Cape Town, 2002
In the last decade, the South Amcan Electricity Supply Commission would have had their ability to serve an ever demanding public severely tested. With the dilemma of providing electricity supply through hazardous environmental conditions, and with prospects of supplying power even beyond South Afiican borders, the need for a comprehensive damage and power delivery assessment strategy becomes all the more relevant. The rapid growth being made in the evolution of so called "intelligent" structures, with inherent sensor, actuator and control mechanisms built in can have direct influence on a power distribution network. At least in the foreseeable future, the impact ofphotonic sensors with inherent miniaturization, a foremost candidate in Smart System technology, can play a vital role in damage assessment of a potentially large network such as that found in the supply ofelectricity. Smart systems are nonliving systems that integrate the functions of sensing, actuation, logic and control, to respond adaptively to changes in their condition or environment to which they are exposed, in a useful and usually repetitive manner. Sensors are a fundamental part of the evolution of such systems and form the basis for the topic of this dissertation. The use ofoptical fiber sensors is increasing widely mainly due to their (a) miniature size, (b) remote signal processing ability, and (c) multiplexing capabilities. Because of the above features a variety of optical fiber sensing techniques has evolved over the years having potential for a myriad of applications. In this work a systems model and equations was developed for modeling the propagation of light in a optical waveguide, in order to study a Fabry Perrot sensor topology for application as a miniaturised sensor in a new type of smart structure, namely a smart electrical power system.

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26

Bolton, Jason C. "Spectroscopic Analysis of Hemolymph and Hemocyanin for the Development of a Non-Invasive Lobster Vitality Sensor." Fogler Library, University of Maine, 2008. http://www.library.umaine.edu/theses/pdf/BoltonJC2008.pdf.

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27

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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28

Liang, Yuanxin. "Respiration monitoring with a fibre optic sensor." Swinburne Research Bank, 2008. http://hdl.handle.net/1959.3/47121.

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Thesis (PhD) - Swinburne University of Technology, Faculty of Engineering and Industrial Sciences, Centre for Atom Physics an Ultra-fast Spectroscopy, 2008.
A thesis submitted for the degree of Master of Engineering, Centre for Atom Physics an Ultra-fast Spectroscopy, Faculty of Engineering and Industrial Sciences, Swinburne University of Technology, 2008. Typescript. Bibliography: p. 143-149.

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29

Patel, Ketan M. "Spatially Resolved Equalization: A New Concept in Intermodal Dispersion Compensation for Multimode Fiber." Diss., Available online, Georgia Institute of Technology, 2004:, 2004. http://etd.gatech.edu/theses/available/etd-11162004-114639/unrestricted/patel%5Fketan%5Fm%5F200412%5Fphd.pdf.

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Thesis (Ph. D.)--Electrical and Computer Engineering, Georgia Institute of Technology, 2005.
Ralph, Stephen E., Committee Chair ; McLaughlin, Steven W., Committee Member ; Buck, John A., Committee Member ; Laskar, Joy, Committee Member ; Raman, Chandra, Committee Member. Vita. Includes bibliographical references.

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30

Ravikumar, K. C. "Spread spectrum techniques for distributed multimeasurand optical fiber sensors." Thesis, Virginia Tech, 1993. http://hdl.handle.net/10919/41615.

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Spread spectrum techniques offer an alternate solution to the urgency for distributed optical fiber sensors. These techniques are based on the properties of pseudorandom sequences that have triangular autocorrelation functions with peaks only at regions of no delay. This affords an opportunity to give the desired signal a power advantage over many types of interference and noise. A study in employing spread spectrum techniques for multiplexing optical fiber sensors is presented. A mathematical analysis of the system is conducted with due consideration given to performance issues. Simulations in software are conducted to characterize system performance. Hardware developed for this project operates at over 1 Mbps and is capable of simultaneously monitoring four sensors. Real time experiments conducted on these multiplexed sensors affirm the technical feasibility of the system. Configurations for viable applications of the system are also suggested.

Master of Science

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31

Hamner, Vincent N. "A fiber optic polarimeter for use in chemical analysis." Thesis, Virginia Tech, 1990. http://hdl.handle.net/10919/42892.

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Polarimetry, as applied to chemical analysis, deals with the determination of the extent and direction that an optically active chemical species will rotate incident linearly polarized light. Although well developed for physical sensing, the technique of fiber optic polarimetry for chemical sensing remains in its infancy. This thesis is concerned with the design and development of an optical fiber polarimeter which measures the optical rotation of linearly polarized light that occurs in a sensing region between two multi-mode optical fibers. Over short distances, the polarization preserving capabilities of large-core multi-mode optical fibers were investigated. Polarimetric analyses were performed using sucrose and quinine hydrochloride. The instrument has a resolution of O.O8Â·, and is an excellent platform for an LC or FIA detector. Its more intriguing future lies in evanescent field sensor applications and studies of chiroptical surface interactions.
Master of Science

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32

Geddis, Demetris Lemarcus. "Single fiber bi-directional OE links using 3D stacked thin film emitters and detectors." Diss., Available online, Georgia Institute of Technology, 2004:, 2003. http://etd.gatech.edu/theses/available/etd-04082004-180141/unrestricted/geddis%5Fdemetris%5Fl%5F200312%5Fphd.pdf.

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33

Xu, Ying. "Detection of delamination in composites with fiber optic sensor /." View abstract or full-text, 2004. http://library.ust.hk/cgi/db/thesis.pl?CIVL%202004%20XU.

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Thesis (Ph. D.)--Hong Kong University of Science and Technology, 2004.
Includes bibliographical references (leaves 194-209). Also available in electronic version. Access restricted to campus users.

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Reichard, Karl Martin. "Distributed-effect modal domain optical fiber senors for flexible structure control." Diss., Virginia Tech, 1991. http://hdl.handle.net/10919/39420.

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35

Wang, Wei-Chih. "A study of fluid viscosity and flow measurement using fiber-optic transducers /." Thesis, Connect to this title online; UW restricted, 1996. http://hdl.handle.net/1773/5908.

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36

Tipparaju, Venkata Satya Sai Sarma. "An active core fiber optic gas sensor using a photonic crystal hollow core fiber as a transducer." Master's thesis, Mississippi State : Mississippi State University, 2007. http://sun.library.msstate.edu/ETD-db/theses/available/etd-06262007-164352/.

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37

Smithpeter, Colin Lee. "Fiber optic confocal imaging for in vivo detection and diagnosis of pre-cancerous lesions /." Digital version accessible at:, 1997. http://wwwlib.umi.com/cr/utexas/main.

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38

Cheng, Sau Kuen. "Real-time optical fibre sensing of phytoplankton for studies in size distribution and concentration." HKBU Institutional Repository, 1996. http://repository.hkbu.edu.hk/etd_ra/56.

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39

Pierce, Mary E. "Engineering a fiber-optic implantable cardiovascular biosensor /." free to MU campus, to others for purchase, 2004. http://wwwlib.umi.com/cr/mo/fullcit?p1422954.

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40

Schaub, Jeremy Daniel. "Photodetectors and monolithic optical receivers in silicon technologies /." Digital version accessible at:, 2000. http://wwwlib.umi.com/cr/utexas/main.

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41

Hu, Xue-Mei. "An optical fiber sensor for the determination of hydrogen peroxide." Master's thesis, Mississippi State : Mississippi State University, 2008. http://library.msstate.edu/etd/show.asp?etd=etd-04042008-123345.

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42

De, Vries Marten J. "Simultaneous measurement of strain and temperature using liquid core optical fiber sensors." Thesis, This resource online, 1993. http://scholar.lib.vt.edu/theses/available/etd-03042009-040438/.

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43

Wang, Chun-Wei. "Quantitative protein detection in serum samples using fiber-optic biosensors." Birmingham, Ala. : University of Alabama at Birmingham, 2008. https://www.mhsl.uab.edu/dt/2008m/wang.pdf.

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44

Jorgenson, Ralph Corleissen. "Surface plasmon resonance based bulk optic and fiber optic sensors /." Thesis, Connect to this title online; UW restricted, 1993. http://hdl.handle.net/1773/5996.

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45

Furness, Charles Zachary. "Parameter identification of a flexible beam using a modal domain optical fiber sensor." Thesis, Virginia Tech, 1990. http://hdl.handle.net/10919/42058.

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An optical fiber sensor is used for identification of a cantilevered beam under conditions of various concentrated mass loadings. A model of the sensor as well as the dynamic system is developed and used to test the reliability of the identification. Input/output data from an experiment is gathered and used in the identification. A survey of the existing areas of damage detection and parameter identification is included, along with suggestions for incorporating fiber optic sensors into existing techniques. The goal of this research was to show that the fiber sensor can be used for identification purposes, and that it is sensitive to parameter changes within the system (in this case concentrated mass changes).

Master of Science

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46

Barker, David G. "Reconstruction of the temperature profile along a blackbody optical fiber thermometer /." Diss., CLICK HERE for online access, 2003. http://contentdm.lib.byu.edu/ETD/image/etd191.pdf.

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47

Jayaprakash, Ashwini. "Innovative scintillating optical fibers for detecting/monitoring gamma radiation." Master's thesis, Mississippi State : Mississippi State University, 2006. http://library.msstate.edu/etd/show.asp?etd=etd-12032006-204412.

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48

Biazon, Filho Alcino José. "Nova técnica de malha fechada para estabilização do ponto de operação de interrogadores de sensores com grade de bragg em fibras ópticas." [s.n.], 2012. http://repositorio.unicamp.br/jspui/handle/REPOSIP/260881.

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Orientador: José Antonio Siqueira Dias
Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Elétrica e de Computação
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Resumo: Sensores de fibra óptica são imunes à interferência eletromagnética (EMI), e são uma excelente escolha para ser usado em ambientes eletricamente ruidosos aplicações em sensoriamento remoto, incluindo aeroespacial, ferroviário equipamentos de segurança militar e em linhas de alta tensão. Outras vantagens incluem o fato de que eles são compactos, leves e os sinais de medição podem ser transmitidos a distâncias muito grandes (da ordem de km). Os interrogadores convencionais para redes de Bragg (FBG) do sensor são equipamentos de custo elevado e não pode ser utilizado em aplicações de baixo custo. Neste trabalho é apresentada uma nova técnica de interrogação robusta e de baixo custo que apresenta uma boa precisão. A técnica, que utiliza um circuito de retroalimentação eletrônico para estabilizar o ponto de operação DC das grades de Bragg, permite a medição simultânea de ambos sinais AC e DC. Um protótipo do interrogador proposto foi projetado e implementado. A técnica exige apenas três componentes ópticos: um laser distribuído, um acoplador óptico e um fotodiodo. O interrogador foi testado com sucesso em uma aplicação de DC (medição de temperatura) e uma aplicação AC (medição de corrente elétrica). Os resultados experimentais mostraram que o controle eletrônico em malha fechada pode controlar o ponto de operação da FBG com uma precisão de ± 2 ppm
Abstract: Fiber optic sensors are immune to electromagnetic interference (EMI), and are an excellent choice for being used in electrically noisy environments sensing applications, including aerospace, rail, military security equipment and in high voltage power lines. Other advantages include the fact that they are compact, lightweight and the measured signals can be transmitted at very large distances (of the order of kilometers). The conventional interrogators for Fiber Bragg Gratings (FBG) sensor are high cost equipment and cannot be used in low cost applications. In this work it is presented a novel robust and low cost interrogation technique that presents good accuracy. The technique, which uses an electronic feedback loop to stabilize the DC operating point of the Bragg gratings, allows the simultaneous measurement of both AC and DC signals. A prototype of the proposed interrogator was designed and implemented. The technique requires only three optical components: a Distributed Feedback Laser, an optical coupler and one photodiode. The interrogator has been successfully tested in a DC application (temperature measurement) and an AC application (electrical current measurement). Experimental results showed that the electronic feedback loop can control the operation point of the FBG with a precision of ±2 ppm
Doutorado
Eletrônica, Microeletrônica e Optoeletrônica
Doutor em Engenharia Elétrica

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49

Seachman, Steven M. "Application of a reflective optical probe to measure solids fractions in a circulating fluidized bed." Morgantown, W. Va. : [West Virginia University Libraries], 2007. https://eidr.wvu.edu/etd/documentdata.eTD?documentid=4988.

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Thesis (M.S.)--West Virginia University, 2007.
Title from document title page. Document formatted into pages; contains xiii, 97 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 72-74).

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50

Klemba, Francielli. "Sensores óticos a fibra aplicados à área de petróleo." Centro Federal de Educação Tecnológica do Paraná, 2005. http://repositorio.utfpr.edu.br/jspui/handle/1/105.

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Este trabalho descreve a produção de redes de Bragg e de período longo em fibras óticas, e a caracterização destas redes como dispositivos sensores na detecção de hidrocarbonetos que fluem em polidutos, bem como na monitoração de sua temperatura. O trabalho foi realizado no Laboratório de Laser da UTFPR. As redes de período longo foram produzidas pela aplicação ponto-a-ponto do arco elétrico de uma máquina de emendas de fibras óticas e caracterizadas como sensores de índices de refração de meios exteriores à fibra. Essa caracterização foi realizada usando diferentes amostras de fluidos tais como, álcool, gasolina, aguarrás, tíner, querosene e nafta. O maior deslocamento em comprimento de onda apresentado pela rede foi de 15,57 nm na presença do querosene. A sensibilidade média ao índice de refração da rede foi 2,6x10-6 pm-1 para a região compreendida entre 1,432 (tíner) e 1,448 (querosene). Esta sensibilidade resulta em uma mínima variação de índice de refração de 2,6x10-5 que pode ser medida por um analisador de espectros óticos com precisão em comprimento de onda de ± 5pm. O tempo de resposta do sensor foi da ordem de 3 segundos. As redes de Bragg foram caracterizadas como dispositivo sensor de temperatura dos fluidos. As redes de Bragg foram produzidas inicialmente em fibras SMF hidrogenadas e posteriormente em fibras fotossensíveis, utilizando a técnica de escrita interferométrica com máscara de fase e laser ultravioleta. Os dispositivos foram caracterizados como sensor de temperatura, tendo sido feito um estudo para estabilização térmica dos mesmos. A sensibilidade das redes variou desde 10,2 nm/ºC até 11,4 nm/ºC. A precisão deste tipo de sensor está intimamente relacionada com a largura de banda espectral da rede, portanto, um sistema de gravação utilizando a técnica de escrita com máscara de fase e laser UV foi implementado, tornando possível a escrita de redes mais longas com menor largura de banda.
This work describes the production of fiber Bragg gratings and long period gratings in optical fibers and their characterization as sensors devices in the detection of hydrocarbons that flow in pipelines, as well as its temperature measurement. The work was accomplished at Laser Laboratory of UTFPR. The long period gratings were produced using the point-to-point electric arc discharge technique from a splice machine and characterized as refractive index sensors of the fiber surroundings. The characterization was accomplished using different samples of alcohol, gasoline, turpentine, thinner, kerosene and naphtha. The biggest wavelength shift presented by the grating was 15.57 nm in the presence of the kerosene. The average refractive index grating sensitivity was 2.6x10-6 pm-1 in the range from 1.432 (thinner) to 1.448 (kerosene). This sensitivity relates to a smallest refractive index variation of 2.6x10-5 that can be measured, for an optical spectrum analizer with wavelength precision of ± 5 pm. The response time of the sensor was 3 seconds for the different samples used. The fiber Bragg gratings were characterized as temperature sensor devices of the samples. The gratings were produced both in SMF hydrogenated and photosensitive fibers, using an ultraviolet laser and a phase mask interferometer. The devices were characterized as temperature sensors, and a study for thermal stabilization of them was carried out. The obtained sensor sensitivity ranged from 10.2 nm/ºC up to 11.4 nm/ºC. As the precision of this type of sensor is related to the bandwidth of the fiber Bragg grating, a writing system technique based on a phase mask and an UV laser was implemented, making possible the writing of long and narrow bandwidth gratings.

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