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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
Lloyd, Glynn D. "Resonant cavity Fibre Bragg grating sensor interrogation." Thesis, Aston University, 2004. http://publications.aston.ac.uk/8007/.
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This thesis presents a novel high-performance approach to time-division-multiplexing (TDM) fibre Bragg grating (FBG) optical sensors, known as the resonant cavity architecture. A background theory of FBG optical sensing includes several techniques for multiplexing sensors. The limitations of current wavelength-division-multiplexing (WDM) schemes are contrasted against the technological and commercial advantage of TDM. The author’s hypothesis that ‘it should be possible to achieve TDM FBG sensor interrogation using an electrically switched semiconductor optical amplifier (SOA)’ is then explained. Research and development of a commercially viable optical sensor interrogator based on the resonant cavity architecture forms the remainder of this thesis. A fully programmable SOA drive system allows interrogation of sensor arrays 10km long with a spatial resolution of 8cm and a variable gain system provides dynamic compensation for fluctuating system losses. Ratiometric filter- and diffractive-element spectrometer-based wavelength measurement systems are developed and analysed for different commercial applications. The ratiometric design provides a low-cost solution that has picometre resolution and low noise using 4% reflective sensors, but is less tolerant to variation in system loss. The spectrometer design is more expensive, but delivers exceptional performance with picometre resolution, low noise and tolerance to 13dB system loss variation. Finally, this thesis details the interrogator’s peripheral components, its compliance for operation in harsh industrial environments and several examples of commercial applications where it has been deployed. Applications include laboratory instruments, temperature monitoring systems for oil production, dynamic control for wind-energy and battery powered, self-contained sub-sea strain monitoring.
3
Shengnan, Geng, Wang Xinglai, and Feng Hui. "FIBER BRAGG GRATING SENSOR SYSTEM FOR MONITORING COMPOSITE AEROSPACE STRUCTURES." International Foundation for Telemetering, 2016. http://hdl.handle.net/10150/624242.
Full textAbstract:
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.
4
Maikisch, Jonathan Stephen. "Compact silicon diffractive sensor: design, fabrication, and functional demonstration." Diss., Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/45882.
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The primary objective of the presented research is to develop a class of integrated compact silicon diffractive sensors (CSDS) based on in-plane diffraction gratings. This class of sensors uses a silicon-on-insulator (SOI) substrate to limit costs, exploit established fabrication processes, enable integration of supporting electronics, and use the well-understood telecommunications wavelength of 1.55µm. Sensing is achieved by combining constant-diffraction-efficiency and highly-angularly-selective in-plane resonance-domain diffraction gratings. Detection is based on the diffraction efficiency of the highly angularly selective grating. In this research, the design processes for the constant-diffraction-efficiency and the highly angularly selective gratings are detailed. Grating designs are optimized with rigorous coupled-wave analysis (RCWA) and simulated with finite-difference time-domain (FDTD) analysis. Fabrication results are presented for the CSDS gratings. An inductively coupled plasma (ICP) Bosch etch process enables grating fabrication to within one percent of designed values with nearly vertical sidewalls. Experimental results are presented for individual CSDS gratings, the prototype sensor, and a prototype linear sensor array. The results agree well with simulation. The linear sensor array prototype demonstrates the intrinsic splitting mechanism and forms the basis of a 2-D sensor array. Finally, a toluene sensor was functionally demonstrated. The proof-of-concept device includes a polymer immobilization layer and microfluidic delivery of toluene. Toluene concentrations as low as 100ppm are measured, corresponding to a refractive index change of 3x10⁻⁴ RIU.
5
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.
6
Igata, Eishi. "Hydrocarbon vapour detection by waveguide-based sensor using Bragg grating reflector." Thesis, University of Oxford, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.365443.
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7
Dowker, Kenneth Paul. "Long period fibre grating as gas sensor for environmental pollution monitoring." Thesis, Sheffield Hallam University, 2003. http://shura.shu.ac.uk/19578/.
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The principle objective of the work presented in this thesis is to investigate and demonstrate the possibility of utilising the inherent properties of long-period gratings (LPGs) to detect the existence and concentration of a given gas in the region immediately surrounding the fibre cladding. The principle and the viability of using LPGs for sensor applications is supported by the preliminary results reported here. However, the sensitivity of the sensor requires further improvement before it can in any way challenge the existing sensors in this field. The operational characteristics and limitations of existing optical sensors are reviewed and the advantages of a LPG based optical sensor highlighted. Thorough explanations of the theory and principles of light propagation, mode formation, and mode coupling in optical fibres are presented. Computer simulations predicting the optical effects due to changes in ambient indices from theoretical conditions are successfully derived, confirming the results obtained by experimental investigation. Various established coating methods are investigated and utilised in the application of optically sensitive compounds adsorbed onto the cladding with different levels of success, the poly-electrolyte self assembly (PESA) and evaporation methods proving most suitable. A novel method of monitoring the build up of PESA layers in-situ using surface plasmon resonance (SPR) methods is introduced. The coating chemicals used in this investigation showed some optical sensitivity at the optimum wavelengths used in optical fibres to the various gases being monitored, in most cases causing a detectable change in the optical characteristics of the modes in the LPG.This study has shown the possibility of using a suitably prepared LPG as a gas sensor. The LPG is coated with a chemical whose refractive index is changed by absorption of a given gas and thus the change in the coupling wavelengths being caused by the existence of the gas. Maximum shifts in coupling wavelength of +/-1.5 nm for relatively high gas concentrations are observed. The possibility of using a coating material which absorbs water, or surrounding the LPG with a suitable liquid is also demonstrated, the refractive index of the coating or liquid and thus the coupling wavelength shift being affected by the reaction of the gas. The possibility of using a single temperature immune LPG for ambient index sensing by observing different coupling wavelengths in the same grating is also reported.
8
Liu, Chen. "Advanced optical fibre grating sensors for biochemical applications." Thesis, Bangor University, 2019. https://research.bangor.ac.uk/portal/en/theses/advanced-optical-fibre-grating-sensors-for-biochemical-applications(29757d94-bfe1-4d75-a4db-8563be1a056f).html.
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This thesis describes a detailed study of advanced fibre optic sensors and their applications for label-free biochemical detection. The major contributions presented in this thesis are summarised below. A self-assembly based in-situ layer-by-layer (i-LbL) or multilayer deposition technique has been developed to deposit the 2D material nanosheets on cylindrical fibre devices. This deposition technique is based on the chemical bonding associated with the physical adsorption, securing high-quality 2D materials coating on specific fibre cylindrical surface with strong adhesion as well as a prospective thickness control. Then a " Photonic-nano-bio configuration", which is bioprobes immobilised 2D-(nano)material deposited fibre grating, was built. 2D material overlay provides a remarkable analytical platform for bio-affinity binding interface due to its exceptional optical and biochemical properties. EDC (1-ethyl-3-(3-dimethylaminopropyl)carbodiimide) and NHS (NHydroxysuccinimide) were used to immobilise bioprobes. This kind of configuration is considered to have many advantages such as: enhanced RI sensitivity, enrich immobilisation sites, improved binding efficiency, selective detection. Followed by this configuration, several label-free biosensors were developed. For example, graphene oxide coated dual-peak long period grating (GO-dLPG) based immunosensor has been implemented for ultrasensitive detection of antibody/antigen interaction. The GO-LPG based biosensor has been developed for label-free haemoglobin detection. Apart from biosensors, the black phosphorus (BP) integrated tilted fibre grating (TFG) has been proposed, for the first time, as BP-fibre optic chemical sensor for heavy metal (Pb2+ ions) detection, demonstrating ultrahigh sensitivity, lower limit of detection and wider concentration range. Ultrafast laser micromachining technology has been employed to fabricate long period grating (LPG) and microstructures on optical fibre. The ultrafast laser micromachined polymer optical fibre Bragg grating (POFBG) has been developed for humidity sensing, showing the significant improvement with the reduced response time.
9
Cooper, David J. F. "Time division multiplexing of a serial fibre optic Bragg grating sensor array." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0001/MQ45424.pdf.
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10
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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11
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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12
Reeves, Richard John. "Demodulation and de-multiplexing of a fibre Bragg grating sensor array using volume holograms." Thesis, Cranfield University, 2009. http://hdl.handle.net/1826/4461.
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The demodulation of a Wavelength Division Multiplexed FBG sensor array by a matching array of holograms hosted within a Volume Holographic (VH) material is considered within this thesis. The FBG sensor elements possess separate quiescent wavelengths and operate within different wavelength ranges. The edge of the transfer function of the demodulating holographic element is aligned with the operating range of the matching sensor element. The holographic element then diffracts a fraction of the sensor signal depending on its instantaneous wavelength. The signals from each of the sensor elements are also diffracted through separate angles to matching detectors so de-multiplexing the sensor array.
A scheme using narrow bandwidth holographic transfer functions to demodulate a two element strain sensor array fabricated 4nm apart is reported. The transfer functions and the hysteresis within the PZT actuator, applying the strain, are represented mathematically and used to process results. These are compared with a normalised saw-tooth voltage waveform applied to the PZT to achieve a high Pearson correlation factor of 0.9992. The holograms however possessed poor diffraction efficiency <1% so severely degrading strain resolution. The crosstalk between the sensors’ channels is measured as -8.3dB.
The demodulation scheme is intensity based so is susceptible to fluctuations in source intensity and fibre bend losses. An intensity reference scheme is therefore demonstrated using two holograms to demodulate a single FBG strain sensor. The sensor’s signal is divided by the two holograms and the intensity of the respective parts recorded on matched photo-detectors. Ratiometric detection is then used to identify changes in applied strain while disregarding fluctuations in source intensity and fibre bend losses. The standard difference over sum equation for ratiometric detection however is modified to take account of the respective holographic transfer functions.
13
Chiu, Chih-Hung, and 邱志鴻. "Fiber grating tilt sensor." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/54464845313846271843.
Full textAbstract:
碩士逢甲大學
電機工程所
99
A tilt sensor mainly composed of long period fiber grating is proposed. The long period grating (LPG) is glued by a plate with slot. The plate make the LPG be suspended and is fixed inside a container. The container is filled with some liquid until half-length of LPG is immersed. When the tilt sensor is inclined, the liquid depth will be changed because of the flowing liquid. The different immersed lengths of LPG result to the transmission power changing. Then we can read the value transmission power to estimate the tilt angle. The normal tilt sensors usually have ability to measure precisely, but can’t be applied to large range of tilt angle. Otherwise, if the tilt sensors can be applied to large range of tilt angle, it just can measure roughly. This dissertation proposes a tilt sensor not only can measure precisely, but also can be applied to large range of tilt angle. So, the tilt sensor will be used in much more field.
14
Guru, Prasad A. S. "Fiber Bragg Grating Sensors : An Exploration Of Applications In Diverse Fields." Thesis, 2012. http://etd.iisc.ernet.in/handle/2005/2507.
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Sensors have become essential elements in human life for safe and comfortable existence in the ever demanding world. Various technologies over decades have contributed in their own way fulfilling innumerable sensing requirements. The discovery of optical sensor technologies has revolutionized the sensing field due to their inherent advantages. Among the large number of fiber optic sensor technologies, FBG based sensors have become widely known and popular within and outside the photonics community and has seen a prominent rise in their utilization.
This thesis explores the use of FBG sensors for a wide range of applications scanning across a variety of engineering and medical applications, in the areas of civil engineering, biomechanical engineering, aerospace engineering, geoengineering, etc. It also deals with newer methods of packaging FBG sensors for the measurement of specific engineering parameters like strain, temperature, pressure, displacement and vibration.
In the field of civil engineering, FBG sensors are employed for strain sensing on a prism and furthermore tested on a full size brick wallet. During this study, emphasis is made on substituting traditional sensors by specially packaged FBG sensors with the intent of either enhancing the sensing system’s performance or in merging/uniting the inherent advantages of FBG sensors.
In the area of biomechanics, a novel sensor methodology using FBG sensors, for measuring surface strains generated on the skin of the calf muscle during various leg exercises is proposed. This methodology is used to address one of the most critical and life threatening issues in long distance air travel, namely the Deep Vein Thrombosis. Further, a FBG sensor based plantar sensing plate, is designed and developed, to measure plantar strain distribution in foot and also to analyze the postural stability.
In the field of aerospace engineering, FBG sensors are used for addressing two of the most vital issues; Structural Health Monitoring (SHM) and direct measurement of pressure and temperature on the surface of an aircraft under hypersonic wind flow. Carbon Fiber Composite coupon level testing is carried out to obtain a generic strain calibration factor for the FBG sensor. Further, FBG sensors are exploited for the direct measurement of absolute temperature and pressure on the leeward surface of blunt cone at hypersonic wind speeds.
In the domain of geoengineering, the feasibility studies have been undertaken to use a FBG as a seismic sensor and as a bore-well characterizing sensor. A novel FBG seismic sensor package is developed using a single FBG sensor to pick up the seismic waves propagating through the ground generated from earthquakes and ground tremors. Further, FBG sensors are used for measurement of temperature profiles in a bore-well to delineate and characterize the behavior of fractures during seasonal climatic changes. To summarize, the present thesis demonstrates a comprehensive experimental study which bring out the utility of FBG sensors in a variety of challenging applications.
15
Yu, Ming-Kun, and 余明坤. "Fiber grating sensor system with reconfigurable function." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/8tdmy9.
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碩士國立臺北科技大學
光電與通訊產業研發碩士專班
99
The purpose of this paper investigates a fiber Bragg grating sensor with reconfigurable function. In this paper, we propose a fiber Bragg grating sensor with reconfigurable function and demonstrate performance, the main network of structure is star-ring network architecture; the sub-network is bus-line architecture, we use remote nodes to achieve the reconfigurable function of fiber Bragg grating sensor and also utilize fiber ring laser to improve the SNR (Signal to Noise Ratio) of Signal, it is effective to increase the reliability and capacity of system. This proposed structure can increase the viability of fiber grating sensor system and prevent environmental accidents. In the future, It''s always helpful to monitor sensor regions such, as tunnels, dams, mountainsides, bridges and buildings because the sensors can be built in these building.
16
TSAI, NING, and 蔡寧. "Smart Fiber Bragg Grating-Based Sensor System." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/7bbp75.
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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.
17
Shan, Ming-Yong, and 沈明永. "Temperature-Independent Fiber Bragg Grating Tilt Sensor." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/56033340015583852617.
Full textAbstract:
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℃。
18
Mahesh, Kondiparthi. "Novel Methods To Interrogate Fiber Bragg Grating Sensors." Thesis, 2010. http://etd.iisc.ernet.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 /
19
Yamdagni, Sumeet. "Fiber Bragg Grating Interrogation Systems." Thesis, 2009. http://hdl.handle.net/2005/925.
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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.
20
Chang, Chin-Yu, and 張岑羽. "Applications of Fiber Grating for Sound Pressure Sensor." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/95831243743248144340.
Full textAbstract:
碩士逢甲大學
電機工程所
96
The content this thesis is to achieve a fiber sensor based on the fiber Bragg grating, magnet and polymer encapsulated in an aluminum cylinder for the measurement of sound pressure level. The magnetic field created by the current signal of microphone output is used to act with the proposed fiber sensor. By using optical spectrum analyzer, the reflective wavelength shift and peak signal level can be obtained. The relationship curve between the grating center-wavelength and the sound pressure level is obtained. Besides, a long period fiber grating is used to be the function of an edge filter, and the fiber grating sensor is combined with it. This setup is used to measure the sound pressure level and the sound frequency simultaneously. Optical Spectrum Analyzer(OSA) is used to detect the power level from output, the relation between the power level and the sound pressure level is obtained.
21
Shen, Feng-Chia, and 沈峰嘉. "Hydrogen Sensor Based on a Polished Fiber Grating." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/86222122938623063269.
Full textAbstract:
碩士逢甲大學
電機工程所
94
The content of this thesis is to investigate the fiber sensor composed of a coating thin-film of Pd material on the polished fiber Bragg grating (FBG) for detecting hydrogen gas. This device can sense the index change of fiber Bragg grating and can improve the sensitivity. The coating material Pd can interact with hydrogen to cause the Pd film-coated to be swelled and then to induce the index change. By this sensing mechanism we can use polished fiber Bragg grating coated with the thin film of Pd to detect hydrogen concentration. In addition, the reflectron spectra of a polished fiber grating in different polishing times to remove different core diameters are investigated and confirmed by simulation results.
22
Chen, Yu-Wen, and 陳裕文. "Study of Fiber Bragg Grating Strain Sensor Systems." Thesis, 2000. http://ndltd.ncl.edu.tw/handle/52862205173316577300.
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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.
23
Tsai, Pei-Tsung, and 蔡佩璁. "Rotating Angle Sensor Based on Fiber Bragg Grating." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/43364734578279626441.
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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.
24
Lien, Yi-Ju, and 連怡如. "Mechanical Force sensor fabrication by polymer diffraction grating." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/63647180579883278429.
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碩士國立臺灣科技大學
機械工程系
93
Optical sensors are unaffected by electromagnetic field interference and can be made relatively compact with a diode source and detector. Optical sensors are also known for their sensitivity and high dynamic range. Furthermore, the sensors can be embedded in most structures with minimal modification. Here we present a new means of transducing strain along the axial direction using a diffractive Bragg grating sensor on polymer materials. The diffraction gratings are successfully fabricated on a polydimethylsiloxane (PDMS) polymer using the holographic interference and micromolding technique. The micro MTS tensile test incorporated with the Raman experiment showed that a relationship between the load and the observed diffraction pattern shift could be obtained. The results show an excellent correlation between the optical measurements and load with a sensitivity of 0.05N. The finite element method is also used to prove the experiment results. The advantage of this sensor is that it doesn’t need any electric power to drive the sensor, it is simple for fabrication, and its cost is lower than the traditional silicon based materials. Another advantage is that the sensor is elastomer material, it doesn’t have poison, and it can be used in the transducing stress on the deformed structure and medical area. It only has little references related to this diffractive Bragg grating sensor on polymer materials, and it needs more research in many different directions to be done. Finally, we hope this method can provide more versatile application and development on sensors.
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Wei, Chuan-Bin, and 魏川濱. "Refractive Index Sensor by using Long Period Grating." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/66161727841049165542.
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碩士正修科技大學
電子工程研究所
99
At present, the traditional sensors mainly use electric capacitors, inductors, strain gage, piezoelectric materials as modulation or sensors devices. Basically, these traditional methods involve voltage and current measurement; so, it is easy to electric, magnetic, mechanical impact of the interference. However, the benefits of fiber optic sensors are light weight, durability, resistant to corrosion, low loss rate and from electromagnetic interference, for the radiation, can also be used after radiation treatment, and it applies to strict environmental requirements. This paper focused on single-mode optical fiber produced by micro-lithography long period grating, and then by hydrofluoric acid etching techniques at different times, to complete a number of different sensitivity of refractive index sensors by long period fiber grating. The long period fiber grating is one of optical fiber passive components. The sensing principle is use the LPG shift resonant wavelength by changing the index of fiber cladding, making the index sensor. The resonant wavelength location depends on the grating period and index modulation. When the cladding index is changed, the grating resonant wavelength will be shifted, which is the operating mechanism of this sensing device. This is part of sensors the adjusted for mode fiber cladding, for the under test solution can be coupled to the refractive index of fiber cladding, so that the effects of grating center wavelength was changed in order to achieve the effect of sensors. Experiment as follows, include the solution identification, and the true-false wine identification, the resonant wavelength difference between true and false wine is 2.2 nm. Water temperature sensing, when the temperature increase from 5 to 80℃, the resonant wavelength differences is 51.1 nm, the average shift is 0.68 nm/℃. Salt concentration sensing, when the Salt concentration increase 0 to 5.70 moles, total spectral changes are 10.2 nm, the average shift is 1.79 nm/mole. Sucrose concentration sensing, when the Salt concentration increase 0 to 2.92 moles, total spectral changes are 33.4 nm, the average shift is 11.42 nm/mole. Therefore, the long-period fiber grating sensor etched by hydrofluoric acid can be used as index and concentration sensors.
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Wang, Hao. "A Phase-shifted Fiber Bragg Grating Based Humidity Sensor." Thesis, 2013. http://hdl.handle.net/10012/7789.
Full textAbstract:
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.
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Zhang, Bowei. "Optical high temperature sensor based on fiber bragg grating." Thesis, 2007. http://spectrum.library.concordia.ca/975851/1/NR37761.pdf.
Full textAbstract:
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
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Chen, Chia-Hsiang, and 陳家祥. "Design of Fiber Grating Measurement System and Dynamical Sensor." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/65031778807946366440.
Full textAbstract:
碩士國立中正大學
機械工程所
94
A fiber-optic measurement system which includes a FBG sensor and a Mach-Zehnder interferometer is developed. A FBG of which center wavelength can be modulated by strain due to photo-elastic effect is utilized as a vibration sensor. A Mach-Zehnder interferometer which includes an ASE light source, two fiber couplers, a photo detector and a PZT actuator is integrated to measure the phase difference induced by this FBG sensor. Two different methods are used in demodulating the measured signal. The first one used a PZT actuator to demodulate the vibration signal to avoid the signal fading. The second one used a 3×3 directional coupler. The performance of the FBG sensor is investigated as compared to a traditional accelerometer. Experimental results show that the interferometer can accurately acquire the vibration signal from the FBG sensor. However the sensitivity of this FBG sensor still needs improvements.
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Yu, Kun-Jie, and 游昆傑. "Resonant waveguide grating based label-free refractive index sensor." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/w5a3tx.
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Chen, Chung-Yen, and 陳重延. "The Study of Cladding-Etched Fiber Bragg Grating Sensor." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/27612211524766990781.
Full textAbstract:
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.
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Wu, Jia-lin, and 吳佳霖. "A Study of Novel Fiber Bragg Grating Vibration Sensor." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/73288648285927160343.
Full textAbstract:
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.
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Kao, Sheng-Chiang, and 高聖傑. "Development of An Optic Fiber Bragg Grating Pressure Sensor." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/32140781814835972875.
Full textAbstract:
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.
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Wang, Yuan-Chang, and 王元昌. "Study of the Tilted Fiber Bragg Grating Biochemical Sensor." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/20563537297923520535.
Full textAbstract:
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.
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蔡源展. "Study of Temperature-Independent Fiber Bragg Grating Vibration Sensor." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/97735464006822955904.
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Huang, Jian-yao, and 黃建堯. "A Study of Novel Fiber Bragg Grating Tilt Sensor." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/57728862054510401283.
Full textAbstract:
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
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Vaughan, Lira. "Low cost, short wavelenght fiber Bragg grating strain sensor systems." Thesis, 2002. http://hdl.handle.net/1957/32353.
Full textAbstract:
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
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Wen, Yuan-Wei, and 溫元煒. "The Development of Measurement Technique for Fiber Bragg Grating Sensor." Thesis, 2001. http://ndltd.ncl.edu.tw/handle/36860759994991586620.
Full textAbstract:
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.
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Liao, Chin-Hsiang, and 廖晉祥. "Fabrication and Application of Optical Fiber Grating Hydraulic Pressure sensor." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/z47v48.
Full textAbstract:
碩士國立高雄應用科技大學
機械與精密工程研究所
102
This research mainly emphasizeson the analysis and application Fiber Bragg Grating (FBG) pressure sensor. FBG consists of thousands of short-period refractive index modulations. FBG has agrating period of approximately 1 μm. When a broadband light source illuminates the FBG, a certain wavelength of the light will be reflected. by means of response loading making Bragg Fiber Grating wavelength showing linear drifting, processing fiber sensor design. Through 0~20 Kg/cm2 water pressure correcting and experimenting, understanding the central wavelength of Bragg Fiber Grating from 1552.48nm shifting to 1553.32nm, the response value is from 0 to 672(με), average 1 Kg/cm2 has 33.6(με) changing. Its experimental range raising and lowering pressure data all show linear development, its fiber sensitivity is 2.67×10-4 MPa-1, the withstanding pressure range is 0~20 Kg/cm2, without the influence of ductility and deformation. Because this experiment 0~10 Kg/cm2 adding pressure has good linear performance, its range can be used. It also means this experiment liquid pressure sensor with development of feasibility and good linear trend change.
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Huang, Jia-Ying, and 黃嘉瑩. "Optical Fiber Immuno-sensor based on Long Period Fiber Grating." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/63007982310996093057.
Full textAbstract:
碩士國立高雄應用科技大學
機械與精密工程研究所
101
In this thesis, the Sandwiched long period fiber grating (SLPFG) and Box-shape long period fiber grating (Box-shape LPFG) were fabricated by thick photoresist stacking technique with SU-8 and etching process in Photolithography as the immuno-sensor. The fabrication makes SLPFG and Box-shape LPFG to obtain LPFG function effectively. First to silanition, the LPFG was immersed in NaOH solution and (3-Aminopropyl)triethoxys (APTES) solution to generate O-H bond and N-H bond on the surface of optical fiber for binding biomolecule. The spectrum were varied strongly when O-H bond binding N-H bond. For SLPFG, the resonant wavelength shift was 18.232nm, the transmission loss increased -2.31dB, and for Box-shape LPFG, the resonant wavelength shift was 0.999nm, and the transmission loss increased -2.66dB. Second to analyze the resonant wavelength and transmission loss for SLPFG and Box-shape LPFG that HDAC6 binding specificity secondary antibodies horseradish peroxidase on the surface of immune-sensors. For SLPFG, the resonant wavelength shift was 15.984nm and the transmission loss increased -12.73dB. For Box-shape LPFG, the resonant wavelength shift was 11.98nm and the transmission loss increased -7.6dB. For separating the cell membranes and impurities, the Mahlavu and SK-Hep1 cells were transferred with expression plasmids and the extraction were drew to the 1.5mL tube As the result shown in Mahlavu, the resonant wavelength shits were steady and transmission loss were -0.22dB. For SK-Hep1 cells, the resonant wavelength shits were 24.27nm and transmission loss were -8.92dB. In conclusion, this immuno-sensor for detecting specific protein for HDAC6 is workable.
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Hsieh, Chien-Wei, and 謝建偉. "Design and Study of Temperature Insensitive Displacement Fiber Grating Sensor." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/77914450905849013650.
Full textAbstract:
碩士國立高雄第一科技大學
光電工程研究所
98
In this paper, we use the sensor based on fiber Bragg grating as sensing element, it will make FBG center wavelength drift to reach sensing effect when the sensor affected by displacements. In this paper, the design of sensors is mainly to sense the displacement. FBG is easily to have misjudgements in sensor value due to the influence of the external environment temperature, so we designed temperature insensitive to make the measured value is more correct. The method of reaching temperature insensitive, the FBG with original single period has been designed and packaged specially and affected by displacement effect, the single period will become to gradient period. The change of the bandwidth with reflected by Fiber Grating, we can measure the bandwidth to determine the value of sensors, finally, it will take the purpose with temperature insensitive. It is proved that the displacement sensor design in this research is feasible through analysis by structural analysis software and experiment, and sensing excellent with maximum bandwidth value of 3.208 nm and displacement of sensing range is 0-10.5 mm, the sensitivity of sensor is 0.264 nm/mm. The performance of sensor is better than other research. The better performance in temperature insensitive test is the range of temperature at 20℃-45℃, the maximum error value is 0.045 nm, minimum error value is 0.03 nm. It can be used in bridge and machine monitored, that don’t need to sense for temperature compensation also reduce the cost of sensor applications.
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ChangJian, Hung-Yu, and 張簡鴻宇. "Magnetic Fiber Sensor By Using Air-Gap Long Period Grating." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/37610898719603333051.
Full textAbstract:
碩士逢甲大學
電機工程所
98
The content of this thesis proposes the magnetic sensor based on an air-gap long period fiber grating (AG-LPG). This sensing device is composed of an AG-LPG fabricated by the semiconductor manufacturing process and surrounded with a smart materials-magnetic fluid. The AG-LPG is fabricated by combining the fiber side-polishing, fiber lithography and fiber etching method to produce the periodic air-gap grating in the core along the fiber axis of single mode fibers. Then, the grating region is immersed in the magnetic fluid and then packaged for achieving the magnetic sensor. The change of the surrounding refraction index (SRI) by magnetic field and the grating period will affect the resonant peak shift as well. For the measurement of forward DC magnetic field, the maximum shift of resonant wavelength of 14.4 nm in the field range from 3.3 to 114.8 Gauss is experimentally demonstrated with the sensitivity of about 0.12737nm / Gauss. For measuring the backward magnetic field, the experimental results demonstrated that the shift of resonant wavelength of 9 nm is obtained in the field range from -114.8 to -3.3 Gauss, which corresponds to the sensitivity of about -0.06778nm / Gauss. For the measurement of AC magnetic field, the frequency increment in the constant voltage will reduce the number of magnetic chains and then to decrease the refractive index of magnetic fluid materials, which will cause the wavelength shift toward the shorter-wavelength side. However, with increasing magnetic field-magnitude in a constant frequency, the index of magnetic fluid will increase due to the number increment of lead flux and then to cause the grating wavelength shift toward the longer-wavelength side. The novel magnetic fiber sensor can be applied in the measurement magnetic filed of dangerous or special environment.
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Lai, Lung-Hui, and 賴隆輝. "Piezoelectric-Modulated Sound Pressure Sensor Using a Fiber Bragg Grating." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/56270128604564116389.
Full textAbstract:
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.
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Yeh, Tzonghua, and 葉宗樺. "Temperature-Independent Fiber Bragg Grating Sensor Used in Force Measuring." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/03639300544270868973.
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An, Chih-Yu, and 安治宇. "The research with temperature compensation of Fiber Bragg Grating Sensor." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/41135887309515757766.
Full textAbstract:
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.
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CHIU, YUNG-DA, and 邱勇達. "Fabrication and Application of miniature tilted fiber Bragg grating sensor." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/rmqp5w.
Full textAbstract:
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.
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Bostock, Riccardo. "An oceanographic pressure sensor based on an in-fibre Bragg grating." Thesis, 2020. http://hdl.handle.net/1828/11693.
Full textAbstract:
Deep-ocean pressure measurements are a necessary component for ocean characterization and oceanographic monitoring. Some principle applications such as tsunami detection and ocean floor subsidence are reliant on deep-ocean pressure measurement data. The deep ocean is a challenging environment especially for pressure measurements; discerning pressure changes that are a small fraction of the ambient pressure calls for intelligent engineering solutions.
An ocean-deployable concept model of a pressure sensor is developed. The design is based on a diaphragm transducer intended for measuring hydrostatic pressure changes on the order of 1 centimeter of water (cmH2O) while exposed to ambient pressures several orders of magnitude greater for up to 2500 meters of water (mH2O). Two laboratory-scale pressure sensors are fabricated to test the fundamental principle of the proposed concept at lab-safe pressures. One is a single-sided sensor exposed to atmospheric pressure. The second sensor is a two-sided design that operates at a defined target depth pressure and measures the differential pressure across both faces of the diaphragm.
The sensor design built for atmospheric pressure testing observed a mean experimental sensitivity of 6.05 pm/cmH2O in contrast to 6 pm/cmH2O determined theoretically. The percent error between the experimental and theoretical values is 0.83%. The second design was tested at target depth pressures of 10, 20, 40, and 60 psi (7, 14, 28, and 42 mH2O) and performance was within 5.8%, 2.8%, 0.7%, 4.0% respectively when considering percent error of the mean experimental and theoretical. The repeatability was sufficient for a given sample and pressure response within the range proposed in theory when a pressure preload was present to the diaphragm. Future work will aim at developing a design concept that incorporates a piston and is tested at a higher hydrostatic pressure system, and within ocean waters. A deployment plan and consideration of challenges associated with ocean testing will be accounted for.Graduate
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LIOU, FANG-KUEI, and 劉芳魁. "Both Voltage Sensor and Liquid-Level Sensor Based on a Fabry-Perot Fiber Bragg Grating Resonator." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/h39hba.
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Chethana, K. "Design, Development and Validation of Fiber Bragg Grating Sensor Based Devices for Detecting Certain Healthcare Parameters." Thesis, 2016. http://hdl.handle.net/2005/3041.
Full textAbstract:
Several sensor technologies have been developed and experimented over the last few decades to cater various needs of medical diagnostics. Among these, fiber optic sensors, in particular, Fiber Bragg Grating (FBG) based sensors have attracted considerable attention due to their inherent advantages such electrical passiveness, immunity to Electro Magnetic Interference (EMI), chemical inertness, etc. The present research work focuses on design, development and validation of FBG sensor based devices for measurement of certain healthcare parameters in the context of foot function/gait cycle, cardiac and breathing activity, nostril dominance, hand grip/wrist angle force function, etc. The experimental work presented here emphasizes on the effectiveness and competitiveness of the FBG devices developed, in comparison with standard tools such as Accelerometer, Load cell, Electronic Stethoscope, Electromyogram and Dynamometer.
In the field of human balance, stability and geriatrics, two independent FBG devices namely, Fiber Bragg Grating based Stability Assessment Device (FBGSAD) and Optical Sensor Ground Reaction Force measurement Platform (OSGRFP) have been designed, developed and experimented for postural stability assessment and gait analysis respectively. The result of these studies have significant implications in understanding of the mechanism of plantar strain distribution, identifying issues in gait cycles, detecting foot function discrepancies, identifying individuals who are susceptible to falls and to qualify subjects for balance and stability.
In the field of ergonomic assessment, Fiber Braggs Grating based Hand Grip Device (FBGHGD) is designed and developed for the measurement of hand grip force which helps in the understanding of several important biomechanical aspects such as neuromuscular system function, overall upper-limb strength, vertebral fracture, skeletal muscle function, prediction of disability, incapacity, mortality and bone mass density (forearm, skeletal sites, spine, hip etc.). Further as an extension of this work, the FBGHGD is used for measurement of force generated by the wrist in different positions of the flexion and extension which relates to the wrist muscle activity and its enactment.
In the field of cardiac activity monitoring, a novel, in-vivo, non-invasive and portable device named Fiber Bragg Grating based Heart Beat Device (FBGHBD) is developed for the simultaneous measurement of respiratory and cardiac activities. The work involves designing FBGHBD, validating its performance against traditional diagnostic systems like electronic stethoscope, exploration of its clinical relevance and the usage of FBGHBD in studies involving normal persons and patients with myocardial infarction. The unique design of FBGHBD provides critical information such as nascent morphology of cardiac and breathing activity, heart rate variability, heart beat rhythm, etc., which can assist in early clinical diagnosis of many conditions associated to heart and lung malfunctioning. Further, the scope of this work extends towards evaluating several signal processing algorithms and demonstrating a suitable signal processing architecture for real-time extraction of heart beat and respiratory rates along with its nascent morphologies for critical health care application.
In the area of breath monitoring, a Nostril Pressure and Temperature Device (NPTD) is designed and developed which aims at simultaneous, accurate and real-time measurement of nostril air flow pressure and temperature to aid in clinical diagnosis of nasal dysfunction and associated nose disorders. The results of NPTD can offer certain vital features like breathing pattern, respiratory rate, changes in individual nostril temperature/pressure, nostrils dominance, body core temperature etc., which can assist in early clinical diagnosis of breathing problems associated with heart, brain and lung malfunctioning. Since the research work in this thesis involve experiments engaging human subjects, necessary approvals from the ethical committee is obtained before the experiments and required ethical procedures are followed during all the experimental trials.
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Plett, KRISTA. "Development and Characterization of Polysiloxane Polymer Films for Use in Optical Sensor Technology." Thesis, 2008. http://hdl.handle.net/1974/1527.
Full textAbstract:
A novel sensor using a polymer coated long-period grating (LPG) has been proposed for monitoring levels of organic contaminants in air or water systems. The sensor operates by detecting refractive index changes in the polymer coating as analytes partition in. Polymer coatings used must be able to reversibly and reproducibly absorb contaminants of interest from the sample and have a refractive index just below that of the fiber cladding.
The synthesis and characterization of several chemically selective polysiloxanes is described. Pre-polymer materials are made through the catalyzed condensation of silane monomers. Different functional groups are incorporated either through polymerizing functionalized monomers, or by post-functionalizing the polymer through a platinum-catalyzed hydrosilylation reaction. The pre-polymer materials are crosslinked into elastomeric films using titanium(IV) tetraisopropoxide. The polymer refractive index is controlled through altering the ratios of functional groups within the polymer or changing the loading levels of titanium. Four polymers were made, having different functional groups and optimized refractive indices for use on the proposed sensor.
The partition coefficients for the polymers with a variety of solvents are calculated and compared. Each polymer was found to have a slightly different chemical selectivity pattern, demonstrating that a set of polymers could be used to generate a sensor array. Partition coefficient data was calculated from the gas phase by considering the change in polymer refractive index as the solvents partitioned into the polymer. The Lorentz-Lorenz equation was used to model the relationship between the change in refractive index and the solvent concentration within the polymer.
Finally, polymers were applied to LPGs and used to successfully detect various solvents from the gas phase. This was accomplished by monitoring the entire LPG spectrum, and also by considering loss at a single wavelength using fiber-loop ring-down spectroscopy.Thesis (Ph.D, Chemistry) -- Queen's University, 2008-09-26 15:28:35.603
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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.
Full textAbstract:
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.)