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1
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.
2
Shengnan, Geng, Wang Xinglai i Feng Hui. "FIBER BRAGG GRATING SENSOR SYSTEM FOR MONITORING COMPOSITE AEROSPACE STRUCTURES". International Foundation for Telemetering, 2016. http://hdl.handle.net/10150/624242.
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To investigate strain-sensitive characteristics of fiber Bragg grating (FBG) sensors, a minimal
sensing system consisting of multiplex FBG sensors and signal demodulating and processing
instruments was constructed. FBG sensors were designed with different package structures for
respectively sensing strain or temperature parameters, and they returned
measurand-dependent wavelengths back to the interrogation system for measurement with
high resolution. In this paper, tests were performed on structure samples with step-wise
increase of deformations. Both FBG sensing system and strain gages were tested and
compared. Experimental work proved that the FBG sensing system had a good level of
accuracy in measuring the static response of the tested composite structure. Moreover the
additional advantages such as damp proofing, high sampling rates and real-time inspection
make the novel system especially appropriate for load monitoring and damage detection of
aerospace structures.
3
Al-Tarawneh, Mu'ath. "Traffic Monitoring System Using In-Pavement Fiber Bragg Grating Sensors". Diss., North Dakota State University, 2019. https://hdl.handle.net/10365/31539.
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Recently, adding more lanes becomes less and less feasible, which is no longer an applicable solution for the traffic congestion problem due to the increment of vehicles. Using the existing infrastructure more efficiently with better traffic control and management is the realistic solution. An effective traffic management requires the use of monitoring technologies to extract traffic parameters that describe the characteristics of vehicles and their movement on the road. A three-dimension glass fiber-reinforced polymer packaged fiber Bragg grating sensor (3D GFRP-FBG) is introduced for the traffic monitoring system. The proposed sensor network was installed for validation at the Cold Weather Road Research Facility in Minnesota (MnROAD) facility of Minnesota Department of Transportation (MnDOT) in MN. A vehicle classification system based on the proposed sensor network has been validated. The vehicle classification system uses support vector machine (SVM), Neural Network (NN), and K-Nearest Neighbour (KNN) learning algorithms to classify vehicles into categories ranging from small vehicles to combination trucks. The field-testing results from real traffic show that the developed system can accurately estimate the vehicle classifications with 98.5 % of accuracy. Also, the proposed sensor network has been validated for low-speed and high-speed WIM measurements in flexible pavement. Field testing validated that the longitudinal component of the sensor has a measurement accuracy of 86.3% and 89.5% at 5 mph and 45 mph vehicle speed, respectively. A performed parametric study on the stability of the WIM system shows that the loading position is the most significant parameter affecting the WIM measurements accuracy compared to the vehicle speed and pavement temperature. Also the system shows the capability to estimate the location of the loading position to enhance the system accuracy.
4
Bigué, Jason. "Development of a novel serially multiplexed fiber Bragg grating sensor system using Fourier analysis". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp01/MQ28815.pdf.
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Abdi, Abdeq M. "Structural Monitoring With Fiber Bragg Grating Strain Sensor Array and Optical Frequency Domain Reflectometry". Diss., Tucson, Arizona : University of Arizona, 2005. http://etd.library.arizona.edu/etd/GetFileServlet?file=file:///data1/pdf/etd/azu%5Fetd%5F1399%5F1%5Fm.pdf&type=application/pdf.
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Li, Kuo. "A novel method of Fiber Bragg Grating (FBG) strain modulation and its application in FBG accelerometers". Thesis, Queensland University of Technology, 2014. https://eprints.qut.edu.au/76108/4/Kuo_Li_Thesis.pdf.
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This thesis has systemically investigated the possibility of improving one type of optical fiber sensors by using a novel mechanism. Many parameters of the sensor have been improved, and one outcome of this innovation is that civil structures, such as bridges and high-rise buildings, may be operated more safely and used longer.
7
Egorov, Jacob. "Wavelength accuracy study for high-density Fiber Bragg grating sensor systems using a Rapidly-Swept Akinetic-Laser source". DigitalCommons@CalPoly, 2016. https://digitalcommons.calpoly.edu/theses/1654.
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This thesis studies the center wavelength accuracy of a Fiber Bragg Grating Sensor system that has a large number of sensor elements both as a function of wavelength and as a function of position. Determining the center wavelength of each of the fiber optic sensors is a critical parameter that ultimately determines sensor accuracy. The high density environment can result in degradation of accuracy of the center wavelength measurement. This thesis aims to quantify this measurement error both with theoretical and experimental studies.
There are many sensing applications where optical fiber sensors are preferred over electrical sensors, such as the oil and gas industry where fiber optic sensors are used to monitor wells and pipelines due to their low signal degradation over long distances and immunity to harsh physical environments. Fiber Bragg grating (FBG) sensors in particular have widespread use because of their versatility, measurement sensitivity, and distributed multiplexing abilities. In conventional wavelength multiplexing, up to 50 FBG sensors are spread out over a band of 100nm, each with a center wavelength difference large enough so that each element can be individually measured. However, numerous sensing applications require several hundred to over a thousand sensors cascaded together on a single fiber. These sensor arrays use a combination of WDM and TDM for measurements, where many FBG sensors with the same center wavelength are separated by a long enough length of fiber so that the reflected signals are separated in time.
These Wavelength-to-Time Domain Multiplexing (W-TDM) measurements are enabled by Insight Photonic’s new ‘akinetically’ swept, all-semiconductor laser. This laser is a Vernier-Tuned Distributed Bragg Reflector (VT-DBR) device, capable of rapidly sweeping through different wavelengths without any moving parts. Attributes that make this laser superior to mechanically-swept lasers include: 1) short and long term consistent sweep-sweep reliability, 2) availability at many wavelengths, 3) a narrow linewidth with single longitudinal mode, and 4) the ability to do non-traditional sweep patterns that facilitate measurement of high-density sensor networks.
In this thesis, experiments will be performed in the lab with the Insight VT-DBR laser to determine how accurately the center wavelength of a single Fiber Bragg grating can be measured. Experiments will also be performed with two and three FBGs to compare different algorithmic approaches to measurements. The second part of the thesis will simulate both single and multiple FBG sensor environments, comparing the center wavelength measurement accuracy results for different parameters including signal-to-noise ratios, wavelength point density, FBG loss and width, and multiple algorithmic approaches. The results of these experiments and simulations will demonstrate how accurate a FBG sensor system is at particular parameters, which will be useful to those designing a sensor network or performing similar experiments.
8
Musa, Shah M. "Real-Time Signal Processing and Hardware Development for a Wavelength Modulated Optical Fiber Sensor System". Diss., Virginia Tech, 1997. http://hdl.handle.net/10919/30679.
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The use of optical fiber sensors is increasing widely in civil, industrial, and military applications mainly due to their, (a) miniature size, (b) high sensitivity, (c) immunity from electro-magnetic interference, (d) resistance to harsh environments, (e) remote signal processing ability, and, (f) multiplexing capabilities. Because of these advantages a variety of optical fiber sensing techniques have evolved over the years having potentials for myriad of applications. One very challenging job, for any of these optical fiber sensing techniques, is to implement a stand alone system with the design and development of all the signal processing models along with the necessary hardware, firmware, and software satisfying the real-time signal processing requirements. In this work we first develop the equations for the system model of the wavelength modulated extrinsic Fabry-Perot interferometric (EFPI) optical fiber sensor, and then design and build all the hardware and software necessary to implement a stand-aPh. D.
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Wang, Zhuang. "Intrinsic Fabry-Perot Interferometric Fiber Sensor Based on Ultra-Short Bragg Gratings for Quasi-Distributed Strain and Temperature Measurements". Diss., Virginia Tech, 2006. http://hdl.handle.net/10919/30213.
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The health monitoring of smart structures in civil engineering is becoming more and more important as in-situ structural monitoring would greatly reduce structure life-cycle costs and improve reliability. The distributed strain and temperature sensing is highly desired in large structures where strain and temperature at over thousand points need to be measured simultaneously. It is difficult to carry out this task using conventional electrical strain sensors. Fiber optic sensors provide an excellent opportunity to fulfill this need due to their capability to multiplex many sensors along a single fiber cable. Numerous research studies have been conducted in past decades to increase the number of sensors to be multiplexed in a distributed sensor network.
This dissertation presents detailed research work on the analysis, design, fabrication, testing, and evaluation of an intrinsic Fabry-Perot fiber optic sensor for quasi-distributed strain and temperature measurements. The sensor is based on two ultra-short and broadband reflection fiber Bragg gratings. One distinct feature of this sensor is its ultra low optical insertion loss, which allows a significant increase in the sensor multiplexing capability. Using a simple integrated sensor interrogation unit and an optical spectrum based signal processing algorithm, many sensors can be interrogated along a single optical fiber with high accuracy, high resolution and large dynamic range. Based on the experimental results and theoretical analysis, it is expected that more than 500 sensors can be multiplexed with little crosstalk using a frequency-division multiplexing technology. With this research, it is possible to build an easy fabrication, robust, high sensitivity and quasi-distributed fiber optic sensor network that can be operated reliably even in harsh environments or extended structures.
This research was supported in part by U.S. National Science Foundation under grant CMS-0427951.Ph. D.
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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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Yau, Man Hong. "Vertical displacement measurement using fibre Bragg grating (FBG) sensors for structural health monitoring of bridges". Thesis, Queensland University of Technology, 2014. https://eprints.qut.edu.au/72911/2/Man_Hong_Yau_Thesis.pdf.
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This thesis developed a practical, cost effective, easy-to-use method for measuring the vertical displacements of bridges using fiber Bragg grating (FBG) sensors, which includes the curvature and inclination approaches. These approaches were validated by the numerical simulation tests on a full scale bridge and the laboratory-based tests. In doing so, a novel frictionless FBG inclination sensor with extremely high sensitivity and resolution has also been developed and validated.
12
Perazzini, Matteo. "Evaluation of FBG strain sensor reliability through analytical, numerical and experimental results". Master's thesis, Alma Mater Studiorum - Università di Bologna, 2021. http://amslaurea.unibo.it/22947/.
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The fiber Bragg grating (FBG) sensor is one of the most suitable sensors for structural health monitoring (SHM) of aircraft structures. In principle, the FBG, with adequate sampling and signal processing techniques, is usually more accurate than classical electrical resistive strain gauge. However, since the most common installation method is surface bonding, some significative differences between the strain in the host structure and the one experienced by the fiber may be observed.
The aim of this work is the evaluation of the fiber Bragg grating optical fiber sensor reliability for strain detection in non-uniform strain conditions. A FBG sensor is surface bonded on a rectangular specimen with a centered hole under tensile loading. A multi device method for the strain detection is created with the use of optical fiber, strain gauge and DIC technologies at the same time. In addition, based on microscopic observations, a 3D finite element model of the bonded optical fiber is created to simulate the behavior of the test specimen and to have an insight into the strain transfer between the host material and the optical fiber core. Lastly, being the test specimen a well-known case in literature, the strain is also computed with closed-form expressions. All the experimental, numerical, and analytical results are then compared.
Taking into account the possible sources of error, the comparison shows coherence between the different results. The optical fiber strain sensor reliability is verified through the multiple device method which represents the starting point for future research activities.
13
Harold, Douglas A. "An Evaluation of Optical Fiber Strain Sensing for Engineering Applications". Thesis, Virginia Tech, 2012. http://hdl.handle.net/10919/41239.
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A fatigue test has been performed on 7075-T651 aluminum specimens which were bonded with polyimide coated optical fibers with discrete Bragg gratings. These fibers were bonded with AE-10 strain gage adhesive. The results indicate that lower strain amplitudes do not produce cause for concern, but that larger strain amplitudes (on the order of 3500 μ) may cause some sensors to become unreliable.
The strain response of acrylate coated optical fiber strain sensors bonded to aluminum specimens with AE-10 and M-Bond 200 strain gage adhesives was investigated with both axial and cantilever beam tests. These results were compared to both the strain response of conventional strain gages and to model predictions. The results indicate that only about 82.6% of the strain in the specimen was transferred through the glue line and fiber coating into the fiber. Thus, multiplying by a strain transfer factor of approximately 1.21 was sufficient to correct the optical fiber strain output. This effect was found to be independent of the adhesive used and independent of the three-dimensional profile of the glue line used to attach the fiber. Finally, this effect did not depend on whether the fiber had a polyimide or an acrylate coating.
Further investigation was conducted on the feasibility of using optical fiber strain sensors for monitoring subcritical damage (such as matrix cracks) in fiber reinforced composite materials. These results indicate that an array of optical fibers which monitor the strain profile on both sides of a composite panel may be sufficient for these purposesMaster of Science
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Guo, Honglei. "Miniaturized Wavelength Interrogation For The Aircraft Structural Health Monitoring And Optofluidic Analysis". Thèse, Université d'Ottawa / University of Ottawa, 2014. http://hdl.handle.net/10393/31180.
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In this thesis, miniaturized wavelength interrogators based on planar lightwave circuits (PLCs) are investigated and developed for the optical fiber sensing applications in the aircraft structural health monitoring (SHM) and optofluidic analysis. Two interrogation systems based on an arrayed waveguide grating (AWG) and an Echelle diffractive grating (EDG) are developed and used to convert the optical sensing signals into strain, temperature, vibration, damage, and humidity information for the aircraft SHM. A fiber Bragg grating (FBG) sensing system using developed interrogators is then demonstrated in a field test for aircraft SHM applications. For optofluidic analysis, a PLCs based optofluidic device consisting of two on-chip lens sets is built to enhance the optical manipulation capability of particles. Then, a solution to a multi-functional Lab-on-a-Chip platform for optofluidic analysis is proposed, which integrates the developed particle maneuvering device, grating-structured sensors, and miniaturized interrogators.
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Morana, Adriana. "Gamma-rays and neutrons effects on optical fibers and Bragg gratings for temperature sensors". Phd thesis, Université Jean Monnet - Saint-Etienne, 2013. http://tel.archives-ouvertes.fr/tel-01064993.
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The nuclear industry shows an increasing interest in the fiber optic technology for both data communication and sensing applications in nuclear plants. The optical fibers offer several advantages and the sensors based on this technology do not need any electrical power at the sensing point, they have a quick response and they can be easily multiplexed: in the case of a temperature sensor, several thermocouples can be substituted by a single fiber, resulting in a decrease of the waste material. The fission reactors are a very harsh environment: it is characterized by the highest dose of gamma-rays, of the order of magnitude of GGy, besides a high flux of neutrons and high operating temperature (300°C for the current reactors, known as generation III). This work has been carried out in collaboration with AREVA, a French industrial conglomerate active in the energy domain, with the aim of realizing a temperature sensor resistant to the environment of nuclear reactor of generation IV, in particular a Sodium-cooled Fast Reactor. The currently used technology, the thermocouples, presents a drift of the measurement due to irradiation, that needs a calibration, and a long response time on the order of seconds. In order to remove the drift, to reduce the response time and to increase the precision, a Fiber Bragg Grating temperature sensor was chosen, in regard to all the advantages of the optical fibers. To understand the behavior of such system in a harsh environment, as the nuclear reactor core, we used an experimental approach based on complementary techniques such as radiation-induced attenuation, photoluminescence, electron paramagnetic resonance and Raman spectroscopies
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Stan, Nikola. "Complete Measurement System for Measuring High Voltage and Electrical Field Using Slab-Coupled Optical Fiber Sensors". BYU ScholarsArchive, 2018. https://scholarsarchive.byu.edu/etd/7053.
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A slab-coupled optical fiber sensor (SCOS) falls into a narrow class of all-dielectric optical fiber electric field sensors, which makes it a perfect candidate for measurements of high electric fields in environments where presence of conductors is highly perturbing to the system under test. Its nonlinear response to high fields requires a new nonlinear calibration technique. A nonlinear calibration method is explained and demonstrated to successfully measure high electric fields, as well as high voltages with dynamic range up to 50 dB. Furthermore, a SCOS can be fitted into narrow spaces and make highly localized measurements due to its small size. This allows a SCOS to be integrated inside a standard high voltage coaxial cable, such as RG-218. Effects of partial discharge and arcing is minimized by development of a fabrication method to avoid introduction of impurities, especially air-bubbles, into the cable during SCOS insertion. Low perturbation of the measured voltage is shown by simulating the introduced voltage reflections to be on the order of –50 dB. It is also shown that a SCOS can be inserted into other cables without significant perturbation to the voltage. A complete high voltage and high electric field measurement system is built based on the high-voltage modifications of the SCOS technology. The coaxial SCOS is enhanced for robustness. Enhancements include packaging a SCOS into stronger ceramic trough, strengthening the fiber with kevlar reinforced furcation tubing and protecting the sensor with metal braces and protective shells. The interrogator is protected from electromagnetic interference with an RF-shielded box. Reduction in power losses introduced by the new PANDA-SCOS technology allows interrogator bandwidths to be increased up to 1.2 GHz. The whole measurement process is streamlined with dedicated software, developed specifically for high voltage and electric field measurements with support for the nonlinear calibration.
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Janoušek, Adam. "Návrh optického vláknového senzoru pro detekci vibrací". Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2020. http://www.nusl.cz/ntk/nusl-412994.
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The master theses deals with a detailed analysis of optical fiber sensors. Specifically, there are discussed optical fibers, various types of sensors and realization optical fiber senzor and senzor system that has been optimized and processed data in real time. In master theses also describes the LabView programming enviroment and uses components, including the entire sensor systém of a sensors system that sends measured data
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Guru, Prasad A. S. "Fiber Bragg Grating Sensors : An Exploration Of Applications In Diverse Fields". Thesis, 2012. https://etd.iisc.ac.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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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.
Pełny tekst źródłaStreszczenie:
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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Sharath, U. "Fiber Bragg Grating Based Sensing Devices for Novel Applications in Bio-medical and Engineering Fields". Thesis, 2015. https://etd.iisc.ac.in/handle/2005/4556.
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Sensors have been an integral part of human life. Various sensor technologies have contributed in their own ways to fulfill specific requirements for aiding human beings. In this context, fiber optic sensors have several advantages such as availability of large number of components from communication industry, small footprint, easy fabrication, and immunity to Electro Magnetic Interference. In the category of fiber optic sensors, Fiber Bragg Gratings (FBGs) have been found to be very useful, because of their high sensitivity, multi-modal sensing ability, large operational bandwidth, and multiplexing capability.
An FBG is a periodic orthogonal perturbation of the refractive index along the longitudinal axis of the core of a single mode optical fiber. The periodic modulation of index of refraction is brought about by exploiting the photosensitivity of a germania- doped silica fiber upon exposure to UV light. FBGs, in the basic form, can sense strain and temperature. However, in recent years, several newer sensing applications of FBGs are being explored and the present thesis is an attempt in this direction.
In this thesis work, Fiber Bragg Grating sensor-based devices have been devised for newer applications in bio-medical and engineering fields. Basically, novel packaging methodologies for FBGs are designed and developed, which transduce the measured parameter to a secondary parameter that can be sensed by the FBG.
In the field of Cardiology, an FBG Pulse Recorder has been developed which has the ability to acquire the radial arterial pulse pressure waveform. It records the beat-to-beat pulse pressure along with the radial arterial diametrical variations. The FBG Pulse Recorder has been employed to measure the blood pressure in conjunction with a sphygmomanometer, using the unique signatures obtained in the radial arterial pulse pressure waveform. By the same methodology, radial arterial compliance, is evaluated. Also, using two FBG Pulse Recorders at the carotid and radial arterial sites the pulse transit time differential is measured which acts as an indicator of variation in systolic blood pressure and pulse wave velocity.
In the field of dentistry, a novel technique for real time dynamic measurement of the maximum individual bite force using Fiber Bragg Grating Bite Force Recorder has been proposed. The results obtained show that bite forces increase along the dental arch and are found to be higher in male than in female. Also, an in-vitro study utilizing the FBG temperature sensor has been carried out to measure the variation of temperature in the pulp chamber during light curing of composite materials.
In the field of seismology, a new methodology for real time dynamic monitoring of seismic vibrations, using a Fiber Bragg Grating Seismic Sensor has been proposed. The validation and field tests are carried out in comparison with a commercial seismometer. Further, the feasibility study for an elephant intrusion monitoring system employing the sensor developed has been put forth.
Furthermore, a displacement device has been devised which converts displacement into strain on a cantilever beam over which the FBG sensor is bonded with the aid of a pivoted arm. This arm provides the necessary mechanical amplification of the displacement by varying the pivot screw position, facilitating tunable sensitivity for the FBG displacement device. Also, the same device has been used for measurement of vibration and with enhanced sensitivity for surface profilometry with a resolution of 175nm.
To summarize, the present thesis demonstrates a comprehensive experimental study which bring out the utility of FBG sensors in variety of challenging applications.
21
TSAI, NING, i 蔡寧. "Smart Fiber Bragg Grating-Based Sensor System". Thesis, 2017. http://ndltd.ncl.edu.tw/handle/7bbp75.
Pełny tekst źródłaStreszczenie:
碩士逢甲大學
光電學系
105
Optical fiber sensor systems have attracted increasing attention with the rise of the optoelectronic industry. Hence, fiber Bragg grating (FBG) device has great potential for sensing in the smart structures and environment. In this thesis, the first experimental setup is fault self-detection technique in FBG-based passive sensor network. Here, once the connecting fiber or FBG sensor is broken, it can be detected and located immediately. Furthermore, the capability of the proposed sensor network also can be enhanced. In the next experiment, the proposed FBG sensor system by utilizing intensity and wavelength division multiplexing (I-WDM) detection technique can increase the capacity and capability. Here, the FBG sensors connect can be connected to the different intensity-coding ports for sensing application. Therefore, the proposed FBG sensor system not only can sense the temperature and strain simultaneously, but also can increase the sensing capacity and capability. In the final experiment, we use the proper cavity loss characteristic for a stable single-longitudinal-mode (SLM) erbium-doped fiber (EDF) ring laser. A proper cavity loss is utilized for suppression of side-mode significantly. Moreover, to reach wavelength-selection, FBG and tunable bandpass filter (TBF) are employed for demonstrated. The output performance and stability of the proposed laser are also discussed.
22
Shan, Ming-Yong, i 沈明永. "Temperature-Independent Fiber Bragg Grating Tilt Sensor". Thesis, 2007. http://ndltd.ncl.edu.tw/handle/56033340015583852617.
Pełny tekst źródłaStreszczenie:
碩士國立清華大學
電機工程學系
95
Our feeling measured the part in the manufacture way, removed the pendulum to hang (but is lays aside iron ball), round components and so on stick, rigid box. mounts pastes the situation; In selects on the material, a working costs more inexpensive water pipe(PVC) acts as the main body, therefore all extremely has the superiority in measuring the stability and the economy. Moreover, was different to the formerly optical fiber diffraction grating inclines the sensory element research, except could obtain the angle which inclined also to be possible the affiliation the direction. We use mixes the erbium optical fiber amplifier (EDFA) the output light (ASE) to take the system needs wide frequency light source (BBS),light source after 1:99 coupler, part of light are detected by power ,When another part of light through first 3dB coupler, can meet the average to disperse (50/50) to two optical fibers diameters ,separately transmits to the reflection wave length shorter Bragg optical fiber diffraction grating (FBG S), the reflection wave length longer Bragg optical fiber diffraction grating (FBG L), This time, will obtain FBG S, the FBG S echo signal. Finally, we then can using optical spectrum analyzer(OSA),power meter read take FBG S, the FBG L superimposition frequency spectrum power as well as the individual frequency spectrum wave length, and according to correlation theoretical calculation ambient temperature as well as angle of tilt size. Present paper use individual frequency spectrum reflection center wavelength change, Surveys the obtained angle at , The accuracy, analysis separately may reach 、 ； Moreover, in temperature survey, Also may the affiliation interpret by the superimposition frequency spectrum power change, The accuracy, analysis separately may reach1.74℃、0.039℃。
23
Yamdagni, Sumeet. "Fiber Bragg Grating Interrogation Systems". Thesis, 2009. https://etd.iisc.ac.in/handle/2005/925.
Pełny tekst źródłaStreszczenie:
This thesis work deals with the development of three different categories of interrogation techniques for Fiber Bragg Grating based sensor networks. Such networks are used for structural health monitoring and other applications.
A bulk grating based interrogation system is described first, which includes an optical source, switch, circulator, embedded controller, and software. The center wavelength determination technique employed is detailed and is shown to be highly accurate from test data. The comparison with resistance strain gauges is presented which shows that the system developed provides an accurate strain reconstruction. The system is also compared with a commercial optical spectrum analyzer and is found to exhibit good accuracy and fidelity. The system has been field tested on an aircraft structure with 14 sensors spread over 4 channels. Strain data reconstruction from these tests is shown to accurately reproduce the loading conditions.
A second system developed is based on the matched filter technique using a mechanical fiber stretcher; the details of this system are presented with a mathematical treatment of the technique. The design of the fiber stretcher is also described. This design is regarded to be novel since it tries to provide large interrogation bandwidths using a parallel topology. The results of tests have shown good resolution and comparative tests with resistance strain gauges have shown accurate reproduction of strain.
Finally, an interrogation system based on a wavelength tunable source is presented. This system is a precursor to a time division multiplexed interrogation system, which has also been described. Three laser configurations have been set up and characterized. The laser sweep tests have been performed on two configurations and a sensor grating reconstruction test has also been carried out.
24
Yamdagni, Sumeet. "Fiber Bragg Grating Interrogation Systems". Thesis, 2009. http://hdl.handle.net/2005/925.
Pełny tekst źródłaStreszczenie:
This thesis work deals with the development of three different categories of interrogation techniques for Fiber Bragg Grating based sensor networks. Such networks are used for structural health monitoring and other applications.
A bulk grating based interrogation system is described first, which includes an optical source, switch, circulator, embedded controller, and software. The center wavelength determination technique employed is detailed and is shown to be highly accurate from test data. The comparison with resistance strain gauges is presented which shows that the system developed provides an accurate strain reconstruction. The system is also compared with a commercial optical spectrum analyzer and is found to exhibit good accuracy and fidelity. The system has been field tested on an aircraft structure with 14 sensors spread over 4 channels. Strain data reconstruction from these tests is shown to accurately reproduce the loading conditions.
A second system developed is based on the matched filter technique using a mechanical fiber stretcher; the details of this system are presented with a mathematical treatment of the technique. The design of the fiber stretcher is also described. This design is regarded to be novel since it tries to provide large interrogation bandwidths using a parallel topology. The results of tests have shown good resolution and comparative tests with resistance strain gauges have shown accurate reproduction of strain.
Finally, an interrogation system based on a wavelength tunable source is presented. This system is a precursor to a time division multiplexed interrogation system, which has also been described. Three laser configurations have been set up and characterized. The laser sweep tests have been performed on two configurations and a sensor grating reconstruction test has also been carried out.
25
Chen, Yu-Wen, i 陳裕文. "Study of Fiber Bragg Grating Strain Sensor Systems". Thesis, 2000. http://ndltd.ncl.edu.tw/handle/52862205173316577300.
Pełny tekst źródłaStreszczenie:
碩士國立交通大學
光電工程所
88
In this thesis we perform a detailed study on two kinds of fiber Bragg grating strain sensor systems. The first system uses a tunable fiber Fabry-Perot filter to form a wavelength-swept erbium-doped fiber laser, which is then used as the tunable optical source for Bragg grating sensor interrogation. A measurement resolution of 1.2me / O Hz is demonstrated by using suitable signal processing methods. The second system uses a Er-fiber ASE broadband source and a linear discriminator fiber Bragg grating for high speed strain measurement. A resolution of 20me has been demonstrated by using a simple experimental setup.
26
Tsai, Pei-Tsung, i 蔡佩璁. "Rotating Angle Sensor Based on Fiber Bragg Grating". Thesis, 2011. http://ndltd.ncl.edu.tw/handle/43364734578279626441.
Pełny tekst źródłaStreszczenie:
碩士逢甲大學
電機工程所
99
In this thesis we proposed three different packaged sensing structures based on fiber Bragg gratings with the characteristics of excellent linearity, fine resolution, nice stability, negligible hysteresis phenomenon, and arbitrary random rotational angle detection. For the first kind of sensor, the rotational angle fiber sensor consists of two FBGs glued axially on a metal rod surface to be bent by repulsion of a magnetic disk. Whenever an input force is exerted on the end of this sensor, the two FBGs are strained by a shaft rotation to result in their central wavelength shifts respectively. This sensor can be used to accurately detect random rotation angle in both static and dynamic conditions. For the second kind of sensor, the rotational position sensor is owing to its miniature size specifically beneficial for fitting in small rotary apparatus, and can especially act as a tiny rotating position sensor. The operation mechanism is mainly based on the difference between the wavelength shifts of two FBGs respectively caused by the bending strain of a cantilever corresponding to the rotating position of rotary shaft. On the other hand, the side-polished chirped fiber Bragg grating is further investigated for using in the measurement of stress, temperature and local pressure. Thus, the third kind of sensor is developed for the rotational angle sensor. The operation mechanism is based on the local pressure on the side polished chirped fiber Bragg grating through the application of transverse force.
27
Wang, Hao. "A Phase-shifted Fiber Bragg Grating Based Humidity Sensor". Thesis, 2013. http://hdl.handle.net/10012/7789.
Pełny tekst źródłaStreszczenie:
A humidity fiber optic sensor based on phase-shifted (PS) Fiber Bragg gratings (FBG) is demonstrated. Compared to the standard FBG sensors, the peak of the PS-FBG slips into 2 narrow peaks and forms a sharp dip in the middle. As a result, the resolution of the measurement will be higher. The sensors used in the experiments were fabricated by coating the PS-FBG surface with a moisture-sensitive polyimide and is based on the strain effect caused by the swelling of the coating after moisture absorption. The same trend seen in a standard FBG sensor can be achieved, but with higher measurement resolution in environments differing by humidity and temperature. This thesis presents simulation and measurement results, including sensitivity and response time, of the PS-FBG sensor approach for humidity sensing, as compared to the standard FBG sensors. Stability and hysteresis are also discussed.
28
Zhang, Bowei. "Optical high temperature sensor based on fiber bragg grating". Thesis, 2007. http://spectrum.library.concordia.ca/975851/1/NR37761.pdf.
Pełny tekst źródłaStreszczenie:
The aim of this thesis is to fabricate a fiber Bragg grating (FBG) temperature sensor that is capable to measure temperatures in excess of 1100°C. For this purpose, two topics have been studied and investigated during this project. One of them is the development of a high temperature resistant molecular-water induced FBGs; and the other is to investigate the effect of microwave-irradiation on the hydrogen-loaded FBG. The molecular-water induced FBGs are different from the other types of FBG. In these devices the refractive index is modulated by the periodic changes of molecular-water concentration within the grating. The device was developed using thermal annealing technology based on hydrogen-load FBG. Thermal stability of these devices was studied by measuring the grating reflectivity from room temperature to 1000°C. The stability of the device was tested by examining the FBG reflectivity for a period of time at certain temperatures. The results show that these devices are extremely stable at temperatures in excess of 1000°C. The hydroxyl concentration in the grating has been also investigated during this thesis. Based on the knowledge of hydroxyl groups inside FBG, a microwave treatment was designed to increase the hydroxyl concentration in the FBG area. The results show that the molecular-water induced grating, which was fabricated using microwave radiated hydrogen-loaded FBI, are stable at temperatures above 1100°C
29
Chen, Chung-Yen, i 陳重延. "The Study of Cladding-Etched Fiber Bragg Grating Sensor". Thesis, 2011. http://ndltd.ncl.edu.tw/handle/27612211524766990781.
Pełny tekst źródłaStreszczenie:
碩士國立高雄大學
電機工程學系碩士班
99
In this thesis, we focus on strain sensitivity, temperature sensitivity and optical spectrum characteristics of cladding-etched fiber Bragg grating in different surrounding materials. Hydrofluoric acid of 48 per centum was used in wet etching process. Experimental results showed that in air the strain sensitivity of the cladding-etched fiber of 17 μm diameter increased 1.7 times as much as that of an unetched fiber and the strain sensitivity of the same cladding-etched fiber also increased 1.8 times in water. However, the temperature sensitivity of the cladding-etched fiber might increase or decrease depending on surrounding materials. The feature of the shift of the reflected Bragg wavelength in different surrounding materials make the cladding-etched fiber Bragg grating a great potential to be used as a refractive index sensor.
30
Wu, Jia-lin, i 吳佳霖. "A Study of Novel Fiber Bragg Grating Vibration Sensor". Thesis, 2009. http://ndltd.ncl.edu.tw/handle/73288648285927160343.
Pełny tekst źródłaStreszczenie:
碩士國立高雄第一科技大學
光電工程研究所
97
This research conducted Mach-Zehnder hybrid interferometer and fiber Bragg grating demodulator as a device to detect vibration signal. The characteristic of fiber Bragg grating on fiber sensing head would reflect specific wave length. When vibration signal transferred to fiber sensing head, it induced to sine-wave strain on the fiber Bragg grating. Slight phrase difference was generated by light guide in the fiber optic because of the vibration strain, and it can be detected by interferometer as well. After transforming light signal into electronic signal, it was conveyed from signal acquisition card to computer in order to save the data and further gain vibration frequency. Also, the amplification structure on fiber optic sensing head strengthened the strain produced by fiber Bragg grating and enlarged period change difference between phrase and grating. Debris flow usually results to low frequency for which available sensors in the market right now are not implemental. Therefore, this research dedicates to design a vibration table with frequency 12-70Hz as the sensor suited for low frequency detecting. The experimental result shows that the sensors invented by this research equip with competence to detect the range of low frequency mentioned above, including ground vibration. Besides, sensors in this research could be widely applied to various places if slightly adjusted, such as mechanical construction and fabrication examination. Comparing experiment in the research to commercial fiber optic accelerometer and piezoelectric accelerometer, the frequency is exactly the same as the others, while the vibration signal is much higher then commercial acceleration but lower than piezoelectric accelerometer.
31
Kao, Sheng-Chiang, i 高聖傑. "Development of An Optic Fiber Bragg Grating Pressure Sensor". Thesis, 2006. http://ndltd.ncl.edu.tw/handle/32140781814835972875.
Pełny tekst źródłaStreszczenie:
碩士國立交通大學
土木工程系所
95
The objective of this research is to develop an optic fiber Bragg grating (FBG) pressure sensor that can be applied in the field for ground water monitoring. The sensor should have the resolution and stability required for the field applications. Water pressure/level can be an important part of the field monitoring system for purposes such as ground subsidence and slope stability. The use of conventional electronic pressure sensors can have drawbacks that relate to electronic devices. If properly designed, FBG sensors have the advantages of small size, light weight and immune to electromagnetic interference. This research develops two types of FBG pressure sensors. The first type modulates the pressure by chirping of FBG (the chirp sensor). The other design is based on uniform stretching of FBG (the stretch sensor). The chirp sensor has the potential of multi-purpose as it can be used a load cell or displacement sensor. The stretch sensor is compact. The thesis describes the design principles of the two FBG pressure sensors, predict the performance of the sensors based on linear elastic analysis of the sensor components. The developed sensors were tested in the laboratory, and the results were compared with the linear elastic analysis.
32
Wang, Yuan-Chang, i 王元昌. "Study of the Tilted Fiber Bragg Grating Biochemical Sensor". Thesis, 2006. http://ndltd.ncl.edu.tw/handle/20563537297923520535.
Pełny tekst źródłaStreszczenie:
碩士國防大學中正理工學院
電子工程研究所
94
The purpose of this study is to implement a biochemical sensor based on a tilted fiber Bragg grating (TFBG). For the slanted gratings, the number of cladding modes and the intensity of the loss peaks of cladding modes are dependant on the tilted angle. This phenomenon can be confirmed by the theoretical calculations and experimental results. However the sensing sensitivity of the higher modes comparing with that of the core mode or lower order modes should be better for monitoring the biochemical media. The detection performance of cladding modes of this fiber sensor will be improved. In this thesis, the spectrum of organic compounds, such as the alcohol, is firstly to be investigated and then by means of experimental measurement, the difference between the carbon bonds and concentration variation can be distinguished. Moreover, TFBG sensor may provide a better performance to recognize an alcohol metamer from other types with the same number of carbon and hydrogen bonds but chemical structure. For sensing the isopropanol, the wavelength shift of the 9th cladding mode is greatly more than that of the fundamental core mode. For measuring biochemical experiments, we could monitor the nitrobacteria decompose and nitrify amino compounds in water. By the daily measurement, we would also observe the pH value of samples to be decreased and the number of bacteria to be increased. The quality of water tends to steady after about the 7th day. Therefore, we could apply this sensor to monitor the quality of water in environmental protection or aquatic farm. Finally, a fiber sensor based on the polyaniline coating technique on the surface of an etched TFBG as a sensing film is developed for detecting volatile toxic vapors. It can effectively be used to detect harmful vapors, such as hydrochloride (HCl) and ammonia (NH3). Besides, it can be extended to the applications of monitoring air pollution and the water quality.
33
蔡源展. "Study of Temperature-Independent Fiber Bragg Grating Vibration Sensor". Thesis, 2005. http://ndltd.ncl.edu.tw/handle/97735464006822955904.
Pełny tekst źródła
34
Huang, Jian-yao, i 黃建堯. "A Study of Novel Fiber Bragg Grating Tilt Sensor". Thesis, 2012. http://ndltd.ncl.edu.tw/handle/57728862054510401283.
Pełny tekst źródłaStreszczenie:
碩士國立高雄第一科技大學
光電工程研究所
100
In this paper, the sensor is mainly based on fiber Bragg gratings (Fiber Bragg gratings, FBG) as the sensing element. When the tilt of the external environment, the sensing architecture to drive the four-fiber grating of which four center wavelengths of FBG, and compare with each other thus achieving the effect of the sensor. The design of the sensor is main to sense the tilt angle which by the FBG center wavelength drift and drift toward to help real-time monitoring of the risk security of the high-rise buildings and major transportation projects. And to change the sensitivity of the sensor for the required sensitivity of different buildings which by adjustable pendulum weight and arm length. With different terrain simulation experiments, not only confirmed that this design could be conform with the building standard of compensation, but also excellent in sensor sensitivity , which can sense the angle tilt range of -4.95 degrees to +4.95 degrees, and the range of sensor sensitivity is 0.121nm /degree ~ 0.384nm / degree. This structure compared with the same type of sensors which can ease of device and the loss rate is low. Then the orientation is easy to determine , which compared with other research papers is competitive. Due to its judgment for the four fiber grating center wavelength, rather than other fiber optic sensors is only observed the change by a single fiber Bragg grating , therefore the device is a temperature insensitive device which as long as in the FBG scope, the result is independent of temperature. This architecture is without modulation system which not only has low costs than other sensor of the past, but also convenient to monitor buildings and traffic engineering. Keywords：fiber Bragg grating (FBG), tilt sensor, temperature insensitive
35
LAI, YING-YI, i 賴穎逸. "Optical-Fiber Wind Speed and Direction Sensor Based on Fiber Bragg Grating". Thesis, 2018. http://ndltd.ncl.edu.tw/handle/tpzw3k.
Pełny tekst źródła
36
Vaughan, Lira. "Low cost, short wavelenght fiber Bragg grating strain sensor systems". Thesis, 2002. http://hdl.handle.net/1957/32353.
Pełny tekst źródłaStreszczenie:
Fiber Bragg grating sensors have been constantly researched for the last ten
years and have finally begun to find use in the commercial market. However, one
of the major factors limiting their widespread use is their system cost. Their
lightweight, flexibility, electromagnetic immunity, and small size make fiber Bragg
grating (FBG) sensors feasible in hostile environments where electrical and
mechanical sensors may not function effectively. These sensor systems utilize
moderately expensive light sources and detectors at telecommunication
wavelengths of 1300 nm and 1550 nm. These are the center wavelengths of the
mass-produced FBGs and FBG phase masks. This thesis addresses the
development of a lower cost short wavelength fiber Bragg grating strain sensor
system using gratings written at 790 nm and 850 nm with the modified phase mask
method recently developed at Oregon State University. Short wavelength gratings
allow the use of less expensive semiconductor sources and silicon detectors, greatly
reducing the overall cost of a strain sensor system from approximately $1600 for a
1300 nm system to $1000 for a 790 nm system.
First, the fundamental properties and historical background of fiber Bragg
gratings were reviewed. Followed by a literature review of the structures,
fabrication methods, and applications of FBGs including sensor applications. The
design, manufacture, and assembly of the new short wavelength strain sensor
system were described including the production of pigtailed super-luminescent
edge emitting light emitting diodes (SELED) from commercial laser diodes, a fiber
recoater, and multiple attempts to write a fiber Bragg grating in the 750-850 nm
wavelength region. Finally, the short wavelength strain sensor system was
compared with a 1300 nm strain sensor detailing the potential cost savings with the
short wavelength system.Graduation date: 2003
37
Wen, Yuan-Wei, i 溫元煒. "The Development of Measurement Technique for Fiber Bragg Grating Sensor". Thesis, 2001. http://ndltd.ncl.edu.tw/handle/36860759994991586620.
Pełny tekst źródłaStreszczenie:
碩士長庚大學
機械工程研究所
89
Fiber gratings have great potential in both the fields of communication or sensing passive devices. The sensors made of fiber grating have the advantage of high sensitivity, multiplexing, and electromagnetic insensitive, due to their lightweight, low cost, and resistance to high temperature and corrosion. In addition to the above, because fiber gratings can be included easily in the composite materials, they are widely used to measure the strain of composite smart materials. But due to the measuring signal being the wavelength shift of the reflected light, the signal processing devices are normally complicated and expensive. In this study we propose a new solution to measure wavelength shift through indirectly measuring the light power. We use the spectrum of the reflected light from two individual fiber Bragg gratings (FBG) to predict the reflection power of the second FBG (G2), which used the reflection of the first FBG (G1) as light source, under different temperatures. Then the reflection power of G2 under different temperature is measured when G1 is kept at 0 oC. Comparing the experiment results with the prediction, we conclude that using simple power meter the wavelength shift can be measured within 2% of accuracy.
38
Lai, Lung-Hui, i 賴隆輝. "Piezoelectric-Modulated Sound Pressure Sensor Using a Fiber Bragg Grating". Thesis, 2010. http://ndltd.ncl.edu.tw/handle/56270128604564116389.
Pełny tekst źródłaStreszczenie:
碩士逢甲大學
電機工程所
98
This thesis shows a sound level sensor based on a fiber Bragg grating (FBG) and a piezoelectric actuator. Deformation is generated by the applied voltage to piezoelectric actuator which is used to measure the sound pressure. An Optical Spectrum Analyzer (OSA) is used to detect reflected peak signal for obtaining the center-wavelength shift . Finally, the relation between the center-wavelength shift of the fiber grating and the sound pressure level are obtained.
39
Yeh, Tzonghua, i 葉宗樺. "Temperature-Independent Fiber Bragg Grating Sensor Used in Force Measuring". Thesis, 2006. http://ndltd.ncl.edu.tw/handle/03639300544270868973.
Pełny tekst źródła
40
An, Chih-Yu, i 安治宇. "The research with temperature compensation of Fiber Bragg Grating Sensor". Thesis, 2010. http://ndltd.ncl.edu.tw/handle/41135887309515757766.
Pełny tekst źródłaStreszczenie:
碩士元智大學
機械工程學系
98
Fiber-optic sensors with small size, light weight, low attenuation and immunity to the electro-magnetic have the advantages over the conventional sensor, had been widely used in communication and sensing technology. In this investigation, the Fiber Bragg Grating (FBG) is incorporated with the specific reflected wavelength to measure the response of strain and the variation of temperature in the vibrational structure. As the linear part of the broadband light sources, the intensity of the light is modulated by the wavelength reflected from the FBG. By measuring the intensity of the light, the wavelength reflected from the fiber bragg grating sensor can be determined, thus, leads to the determination of the strain and temperature in the structures. In this investigation, the fiber bragg grating sensor is attached to the cantilever beam, the experimental tests presented in this research including free vibration (Change the amplitudes and frequency) and temperature change tests. The response of strain and variation of temperature which measured by the Fiber Bragg Grating sensor will be compared with the response of strain and variation of temperature which measured by the strain gauge and the thermocouple. The capability of FBG sensor in measuring the response of strain and the variation of temperature in the vibrational structures is as good as the strain gauge and the thermocouple.
41
CHIU, YUNG-DA, i 邱勇達. "Fabrication and Application of miniature tilted fiber Bragg grating sensor". Thesis, 2017. http://ndltd.ncl.edu.tw/handle/rmqp5w.
Pełny tekst źródłaStreszczenie:
碩士國立高雄應用科技大學
機械工程系
106
In this paper, I have proposed a new coating process for tilted fiber Bragg grating sensor, as well as the new composite sensor for a variety of parameters at the same time monitoring. The sensing principle of Tilted fiber Bragg grating (TFBG) is that the light is refracted from the core mode to the cladding mode, and finally the spectrum of the TFBG produces a corresponding spectrum drift. The first part, the TFBG humidity sensor fabricated using the phase mask method to produce a TFBG that was then etched with five different diameters of 20 μm, 35 μm, 50 μm, 55 μm and 60 μm, after which piezoelectric inkjet technology was used to coat the grating with graphene oxide. According to the experimental results, the diameter of 20 μm yielded the best sensitivity. In addition, the experimental results showed that the wavelength sensitivity was −0.01 nm/%RH and the linearity was 0.996. In the second part, the sensor proposed in the first part is combined with the optical fiber microprobe sensor, which is used as the composite optical fiber sensor to detect the concentration of glucose, the proposed U-shaped tilted fiber Bragg grating sensing the experimental results showed that the wavelength sensitivity was −0.282 nm/% and the linearity was 0.901. The measured standard deviation of less than 0.191 showed good repeatability measurements. In addition, this composite optical fiber sensor in the measurement process can also be the environment for temperature and humidity changes to be corrected, reducing the U-shaped optical fiber sensor measurement of glucose solution due to external environment generated by the error. This optical fiber sensing system has high research and development value, as the TFBG can be used not only for relative humidity sensing and concentration detection, but also in temperature, strain, and magnetic field sensing applications, a versatility that suggests that its future is really limitless.
42
Padma, G. Srivani. "Fiber Bragg Grating Sensor Based Devices for Novel Biomedical Applications". Thesis, 2017. https://etd.iisc.ac.in/handle/2005/4316.
Pełny tekst źródłaStreszczenie:
The present thesis work comprises of design and development of devices based on Fiber Bragg Grating (FBG) sensors for novel biomedical applications. Here, novel packaging methodologies have been utilized for transduction of the measurand parameter into a secondary parameter that can be sensed by the FBG sensor.
Chapter 2 of the thesis deals with the theory of FBGs along with photosensitive property of fibers, theory and fabrication techniques of FBGs, etc. Among the FBG fabrication techniques, the phase mask method of inscription is emphasized, as the FBG sensors utilized for the research work undertaken in the present thesis have been fabricated using this method.
Chapter 3 deals with the study on the usage of a FBG sensor as a communication assistance device. The development of a noninvasive, real-time, communication assistance device employing a FBG sensor, for the assistance of those with restricted communication ability has been presented in this chapter. The communication assistance device comprises of a breath pattern analyzer developed using a FBG sensor, which acquires the exhalation force in the form of strain variations on a cantilever. The present approach is intended to be an alternative to the common approach via brain–computer interface in which an electrode is utilized for learning of brain responses.
Chapter 4 deals with the application of a FBG sensor in the field of dentistry, in which a Bite Force Measurement Device (BFMD) has been demonstrated for the measurement of the individual maximum bite force along the dental occlusion. The developed BFMD facilitates the ability to alter the distance between the biting platform according to the tooth position. Further, clinically relevant bite forces are measured and analyzed.
Chapter 5 provides an insight to another novel application of FBG sensor in the measurement of the Range of Motion (ROM) of joints in human body, which is of prime importance in monitoring the progress of therapeutic procedures. A Fiber Bragg Grating Goniometer (FBGG) has been developed which can be employed to dynamically measure the angular movement of joints. The maximum flexion angles at the elbow along with the plantar and dorsi-flexion angles are evaluated using the FBGG for illustration.
Chapter 6 reports the application of FBG sensor in the field of cardiology, wherein a Fiber Bragg Grating Pulse Probe (FBGPP) developed is described, which comprises the ability to dynamically acquire the arterial pulse pressure waveform. This chapter also deals with the measurement of the Carotid Arterial Pulse Pressure Waveform (CAPPW) of individual subjects, which consists of beat-to-beat carotid pulse pressure, using the proposed FBGPP.
In addition, the pulse wave analysis of the recorded CAPPW is presented, which has been undertaken to evaluate vital cardiovascular parameters and the relationships between them. Lastly, in this chapter, the deployment of the developed FBGPP for radial arterial pulse pressure waveform acquisition in children, has been presented. This study validates the fact of variation of heart rate of children with age. It has been observed that the diastolic time component varies in good accordance with children’s age and in addition it is found to be major contributor to heart rate variation. Furthermore, various cardiovascular parameters are evaluated and compared along with the variation in children’s age.
Finally, chapter 7 gives a summary of the thesis and future directions of the presented research work that are yet to be explored.
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Wu, Ming-Chun, i 吳明純. "Simultaneous Force and Temperature Fiber Sensor Based on Taper-etched Fiber Bragg Grating". Thesis, 2005. http://ndltd.ncl.edu.tw/handle/14997667415312167007.
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碩士逢甲大學
機械工程學所
93
The content of this thesis is to achieve a fiber sensor for simultaneously measuring force and temperature by using a taper-etched fiber Bragg grating, which has high sensitivity in the grating bandwidth and the grating-wavelength shift. The accuracy of the fiber sensor will be confirmed by the good agreement between the theoretical calculations and experimental results. The ANSYS software based on the finite element algorithm is used for the theoretical analysis and calculations. The relationships between the grating wavelength and the allowable strain of optical fiber will be adopted for designing an aluminum-based spring element including how to arrange and stick the optical fiber. Before the fiber sensor is used for measuring the force and temperature simultaneously, the calibration based on the variation of the force and temperature needs to be done. Then the sensor can be operated to measure the force and temperature simultaneously. In addition, the performance by choosing different kinds of adhesives and adhesion for different configurations will be discussed for obtaining the optimum adhesive condition. Due to the fiber existing intrinsic advantages, such as electromagnetic-field interference immunity, small size, light weight, linear characteristics, long-term reliability, bi-directional and multi-port outputs, we design and fabricate the fiber sensor which can simultaneously measure the magnitude of the force and the change of ambient temperature without the effect of electromagnetic magnetic interference. This taper-etched fiber Bragg grating sensor can solve the problem of traditional force sensors based on electrical-resistance strain gauges easily to be affected by electromagnetic fields and can simultaneously monitor the change for ambient temperature.
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Mahesh, Kondiparthi. "Novel Methods To Interrogate Fiber Bragg Grating Sensors". Thesis, 2010. https://etd.iisc.ac.in/handle/2005/1926.
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A novel detection technique to estimate the amount of chirp in fiber Bragg gratings (FBGs) is proposed. This method is based on the fact that reflectivity at central wavelength of FBG reflection changes with strain/temperature gradient (linear chirp) applied to the same. Transfer matrix approach was used to vary different grating parameters (length, strength and apodization) to optimize variation of reflectivity with linear chirp. Analysis is done for different sets of ‘FBG length-refractive index strength’ combinations for which reflectivity vary linearly with linear chirp over a decent measurement range. This work acts as a guideline to choose appropriate grating parameters in designing sensing apparatus based on change in reflectivity at central wavelength of FBG reflection.
A novel high sensitive FBG strain sensing technique using lasers locked to relative frequency reference is proposed and analyzed theoretically. Static strain on FBG independent of temperature can be measured by locking frequency of diode laser to the mid reflection frequency of matched reference FBG, which responds to temperature similar to that of the sensor FBG, but is immune to strain applied to the same. Difference between light intensities reflected from the sensor and reference FBGs (proportional to the difference between respective pass band gains at the diode laser frequency) is not only proportional to the relative strain between the sensor and reference FBGs but also independent of servo residual frequency errors. Usage of relative frequency reference avoids all complexities involved in the usage of absolute frequency reference, hence, making the system simple and economical. Theoretical limit for dynamic and static strain sensitivities
considering all major noise contributions are respectively of the order of 25 pε/ Hz and
1.2nε /
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Mahesh, Kondiparthi. "Novel Methods To Interrogate Fiber Bragg Grating Sensors". Thesis, 2010. http://etd.iisc.ernet.in/handle/2005/1926.
Pełny tekst źródłaStreszczenie:
A novel detection technique to estimate the amount of chirp in fiber Bragg gratings (FBGs) is proposed. This method is based on the fact that reflectivity at central wavelength of FBG reflection changes with strain/temperature gradient (linear chirp) applied to the same. Transfer matrix approach was used to vary different grating parameters (length, strength and apodization) to optimize variation of reflectivity with linear chirp. Analysis is done for different sets of ‘FBG length-refractive index strength’ combinations for which reflectivity vary linearly with linear chirp over a decent measurement range. This work acts as a guideline to choose appropriate grating parameters in designing sensing apparatus based on change in reflectivity at central wavelength of FBG reflection.
A novel high sensitive FBG strain sensing technique using lasers locked to relative frequency reference is proposed and analyzed theoretically. Static strain on FBG independent of temperature can be measured by locking frequency of diode laser to the mid reflection frequency of matched reference FBG, which responds to temperature similar to that of the sensor FBG, but is immune to strain applied to the same. Difference between light intensities reflected from the sensor and reference FBGs (proportional to the difference between respective pass band gains at the diode laser frequency) is not only proportional to the relative strain between the sensor and reference FBGs but also independent of servo residual frequency errors. Usage of relative frequency reference avoids all complexities involved in the usage of absolute frequency reference, hence, making the system simple and economical. Theoretical limit for dynamic and static strain sensitivities
considering all major noise contributions are respectively of the order of 25 pε/ Hz and
1.2nε /
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Fan, Yu. "Characterization of fiber Bragg Grating sensor array embedded in composite structures". Thesis, 2004. http://spectrum.library.concordia.ca/8090/1/MQ94697.pdf.
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FBG (fiber Bragg Grating) sensor becomes a hotspot in recent researches, based on its numerous advantages, especially it can be easily multiplexed to realize sensor network. A number of networking scenarios have been proposed [1] [2], "orthogonal array" is one of the most convincing solutions, in which wavelength division multiplexed FBG sensors are patterned along a single optical fiber and analogical fibers are orthogonally deployed, so that any randomly oriented ambient change can be analytically monitored along two orthogonal sensors of local intersection. Further, by means of various addressing mechanisms [3], stimulus is positioned. However, detailed characterization of a single orthogonal unit is the essence to model entire network. This work reports a set of experiments on an orthogonal FBG array unit embedded in specific Graphite/Epoxy composite structure. First of all, photoelastic behaviour of identical bare FBG fiber was observed, which is to profile an "ideal" FBG strain gage. Then optimization process was carried out to determine the optimal layout for FBG array embedment, which induces minimum perturbation to both sensors and host structure. After optimized specimens were fabricated, tensile loads were applied to specimens. Recurring to surface mounted resistance strain gages, embedded FBG strain gages are recalibrated and their sensing alterabilities are evaluated. Finally, suspended concerns are discussed and conclusions are drawn upon experimental data. (Abstract shortened by UMI.)
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Lin, Chih-Yuan, i 林志遠. "Smart Fiber Bragg Grating Sensor System Based on Mesh Network Topologies". Thesis, 2010. http://ndltd.ncl.edu.tw/handle/13311409350506852370.
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Kuo, Feng-Cheng, i 郭峯誠. "Smart Fiber Bragg Grating Sensor Network Based on Ring-Mesh Architecture". Thesis, 2010. http://ndltd.ncl.edu.tw/handle/39994481444379612275.
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Li, Yi-Cheng, i 李奕澄. "Temperature-Independent Fiber Bragg Grating Tilt Sensor by Optical Power Detection". Thesis, 2014. http://ndltd.ncl.edu.tw/handle/00765116799680681007.
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hsu, yu-hsiung, i 徐裕雄. "Bi-Material Thermal compensation for a Fiber Bragg Grating Pressure Sensor". Thesis, 2005. http://ndltd.ncl.edu.tw/handle/91742970170132023883.
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