Author : Neil J. Guillermo
Publisher : National Library of Canada = Bibliothèque nationale du Canada
Page : 77 pages
File Size : 10,1 MB
Release : 1999
Category :
ISBN : 9780612455740
Author : Neil J. Guillermo
Publisher :
Page : 0 pages
File Size : 32,20 MB
Release : 1999
Category :
ISBN :
The development of temperature compensated fiber optic strain sensors based on fiber Bragg gratings is reported. The various sensors manufactured and tested include a stainless steel capillary tube-encased Bragg grating, a partially-bonded Bragg grating, and a fully embedded Bragg grating. Strain and temperature resolution is accomplished by measuring the characteristic Bragg wavelength shift of each Bragg grating sensor relative to its initial wavelength. Another measurement technique used involves calculating the differential strain measurement between two dissimilar resistive strain gauges to determine strain and temperature. Testing is done using both a self-made convection and industrial oven to regulate the temperature, as well as applying strain to the specimen via bending or tension. The performance of the sensors in tracking the strain and temperature in variable strain and variable temperature environments is reported and evaluated. The development of an in-lab convection oven and a stress machine specifically designed for this thesis is also described. Suggestions are made for improvements to the sensors in addition to further developmental research and possible practical temperature compensated fiber optic strain sensor applications.
Author :
Publisher :
Page : pages
File Size : 44,84 MB
Release : 1999
Category :
ISBN :
Author : Hisham K. Hisham
Publisher : CRC Press
Page : 111 pages
File Size : 21,57 MB
Release : 2019-06-19
Category : Technology & Engineering
ISBN : 1000021726
This book presents the basic principles of optical sensor technology in line with the tremendous development in the concept of optical fibers. In the first four chapters, the book discusses the basic principles of optical sensor technology in a simplified manner, making it suitable for all levels of study and research. The seven remaining chapters are concerned with the practical applications of optical sensor technology in all fields such as oil and gas, civil engineering, medical and military fields and harsh environments.
Author : Eric Udd
Publisher :
Page : 62 pages
File Size : 25,92 MB
Release : 2003
Category : Optical fiber detectors
ISBN :
Author : Oleg Morozov
Publisher : MDPI
Page : 228 pages
File Size : 33,15 MB
Release : 2021-08-18
Category : Technology & Engineering
ISBN : 3036512861
This book is a collection of papers that originated as a Special Issue, focused on some recent advances related to fiber Bragg grating-based sensors and systems. Conventionally, this book can be divided into three parts: intelligent systems, new types of sensors, and original interrogators. The intelligent systems presented include evaluation of strain transition properties between cast-in FBGs and cast aluminum during uniaxial straining, multi-point strain measurements on a containment vessel, damage detection methods based on long-gauge FBG for highway bridges, evaluation of a coupled sequential approach for rotorcraft landing simulation, wearable hand modules and real-time tracking algorithms for measuring finger joint angles of different hand sizes, and glaze icing detection of 110 kV composite insulators. New types of sensors are reflected in multi-addressed fiber Bragg structures for microwave–photonic sensor systems, its applications in load-sensing wheel hub bearings, and more complex influence in problems of generation of vortex optical beams based on chiral fiber-optic periodic structures. Original interrogators include research in optical designs with curved detectors for FBG interrogation monitors; demonstration of a filterless, multi-point, and temperature-independent FBG dynamical demodulator using pulse-width modulation; and dual wavelength differential detection of FBG sensors with a pulsed DFB laser.
Author : Siu Chun Michael Ho
Publisher :
Page : pages
File Size : 46,59 MB
Release : 2012
Category : Cardiac tamponade
ISBN :
The discovery of fiber optics opened the door to a vast new world of possibilities in sensing technology. One important class of fiber optic sensor is the fiber Bragg grating (FBG) structure. The compactness and low loss properties of the FBG make it a highly versatile sensor, and has allowed efficient deployment of FBGs in many different technological fields. This dissertation describes five innovative designs and applications of FBG-based sensors. An FBG sensor was used as a contact level sensor allowing surgeons to gauge their level of contact with the heart wall in order to avoid perforation during cardiac ablation procedures. The sensor was able to determine the onset of contact and was also able to observe a potential warning sign of impending perforation. The second FBG-based sensor was developed for detecting harmful water ingress in civil structures. Through the use of super absorbent polymers (SAPs) and an innovative sensor design, the sensor was able to undergo multiple loading cycles (up to 1 mL was tested) as well as survive flooding conditions. The third FBG-based sensor comprised of two wavelength matched FBG for the measurement of high frequency vibrations. Measurement of acoustic vibrations generated by a piezoelectric wafer up to 100 KHz was demonstrated. A basic identification of a model wind turbine blade was performed using this set up. An FBG sensor network consisting of multiplexed strain, temperature, and water sensors (23 sensors total) was deployed for the monitoring of a grout cube that models the wall of a nuclear containment facility. Cracking, thermal fluctuations and water ingress were detected by the FBG sensor network over a period of about two months. Finally, FBG strain sensors were used to develop a method for the local measurement of bond slip in reinforcing tendons of a prestressed concrete bridge girder. The method allowed the tracking of the entire bond slip process from a local perspective, which was, up to now, not yet accomplished using conventional sensors.
Author : Andrea Cusano
Publisher : Bentham Science Publishers
Page : 331 pages
File Size : 29,60 MB
Release : 2011
Category : Technology & Engineering
ISBN : 160805084X
The book is an exciting source of information for individuals interested in learning about and marketing sensors. The book focuses on scientific and commercial advances in Fiber Bragg Grating (FBG) sensor technology since its discovery over 30 years ago.
Author : Regis J. Van Steenkiste
Publisher : CRC Press
Page : 336 pages
File Size : 34,76 MB
Release : 1996-12-02
Category : Technology & Engineering
ISBN : 9781566764803
FROM THE AUTHORS' PREFACE Sensors operating on interferometric principles and mounted inside optical fibers have recently been considered for measuring strain and temperature. Indeed, such sensors have successfully been employed for measuring pressure or temperature in fluids. Fiber optics sensors are especially adept for such measurements because sensors immersed in fluids can easily be calibrated by tests. Unfortunately, the use of fiber optic sensors inside solids is not as straightforward. Owing to the complex interactions between the sensor and the surrounding material, the relationship between the sensor output and the parameters of interest, namely the strain and temperature inside the material, cannot be determined by simple tests. And without the appropriate relationships, fiber optic sensors do not provide meaningful information. In general, the relationship providing the bridge between the sensor output and the engineering values of strain and temperature must be established via analytical models. The major aim of this book is to present such models for extrinsic and intrinsic Fabry-Perot sensors and for Bragg grating sensors embedded in or mounted on the surface of isotropic or anisotropic solids or immersed in fluids. The scope of the book is limited to the theory of fiber optic strain and temperature sensors. Accordingly, we have taken as our starting point the demodulated sensor signals. The hardware needed to produce these signals is not discussed. It is presumed that the reader is familiar with and has access to the sensor, light source, light detector and demodulator required for generating signals which can then be analyzed and interpreted by the methods presented in the book. The problem necessitates complex analytical developments. To assist the reader, the significant results are summarized in tables, and numerical examples are given illustrating the calculation procedures.
Author : Yupeng Zhu
Publisher :
Page : 121 pages
File Size : 21,1 MB
Release : 2020
Category : Electronic dissertations
ISBN :
This dissertation investigates how to measure dynamic strain including quasi-static strain, vibration, acoustic emission, and ultrasonic waves with fiber Bragg grating based optical fiber sensors. Fiber optic sensors are inherently immune to electromagnetic interference, light weight, small size, corrosion resistance, and capable of multiplexing. With narrow linewidth tunable lasers, the strain induced spectral shift of the Bragg wavelength of the sensor can be demodulated. However, the spectrum of the uniform fiber Bragg grating can not satisfy the sensitivity, resolution, and dynamic range requirements. To address these challenges, we propose and demonstrate a sensor structure based on chirped fiber Bragg gratings combined with Fabry-Perot cavity. Taking advantage of large bandwidth provided by the chirped fiber Bragg grating and the narrow resonance peaks formed by the Fabry-Perot cavity, it can simultaneously achieve high resolution, high sensitivity, and large dynamic range measurement.The second chapter provides the theoretical analysis and numerical simulation on the spectra of chirped fiber Bragg gratings and Fabry-Perot cavities. Based on such context, we are motivated to propose a dynamic strain measurement scenario which take advantage of both high resolution and large dynamic range of the sensor. Due to the different and unique spectral intervals of the notches in the wavelength bandwidth used for measurement, the spectral notches can be unambiguously recognized in each spectral frame without the need for fringe counting. Using this principle, we demonstrated high-resolution and absolute static and dynamic strain measurement. In chapter three, we study the acoustic emission detection with the proposed sensor based on high finesse short cavity structure and explore the potential of using the narrow resonance peak as the laser locking source to reduce the laser noise while functions as ultrasound sensor. Additionally, since the Bragg wavelength is highly related to the polarization, birefringence causes polarization dependent center-wavelength shift. We propose a 90-degree rotation method for grating fabrication in the UV laser beam side exposure technique to reduce the birefringence. Therefore the sensor is insensitive to the polarization state of the laser, the ultrasound detection system can be simplified by omitting the polarization controller. Chapter four expands our work on ultrasonic sensor by using coiled fiber with low-finesse Fabry-Perot interferometer formed by two chirped fiber Bragg gratings. Our work has successfully demonstrated a strain and temperature insensitive fiber-optic ultrasonic detection by combining the coil structure, wide spectral range, and quadrature demodulation. The ultrasonic sensing scheme is immune to the laser wavelength drift, therefore no wavelength locking mechanism is needed. Future work will continue on exploring new design of the sensor structure and optimizing the measurement system to further improve the feasibility while reduce the overall cost.
