Microbending Properties of Optical Fiber Sensors for Load, Pressure Or Pore Water Pressure Measurements PDF Download

Author: Girish Kumar
Publisher:
ISBN:
Category : Optical fibers
Languages : en
Pages : 248

View

Book Description

Author: Paul John Cosentino
Publisher:
ISBN:
Category : Optical fiber detectors
Languages : en
Pages : 156

View

Book Description

Author:
Publisher:
ISBN:
Category : Air travel
Languages : en
Pages : 604

View

Book Description

Author: Pedro Cordero Meza
Publisher:
ISBN:
Category : Interferometry
Languages : en
Pages : 63

View

Book Description
The main focus of this thesis is the development of a MEMS optical pressure sensor capable of giving real-time, accurate measurements to a mid-high pressure range. Some traditional devices for acquisition of parameters such as pressure or temperature have proven to be insufficient to the demands of the markets of research and manufacturing. State-of-the-art sensing technology has led to the construction of more reliable configurations that push the limits of traditional devices. Using micro-machined components is a suitable approach for applications that show restrictions just as limited space, noise measurement or interference created by the inaccuracy of electronic components that are not suited to be in close contact with the sensing medium. A study of the current optical based technologies revealed the current use of extrinsic Fabry - Perot interferometers in the fields of medical, biotechnological and industrial applications. Each field presents a general specific limitation, given the nature of its environment. These mostly include low pressure and temperature ranges, non-protected sensors or super sensitive, expensive devices., The operation of this sensor comprises a non-emissive, optically powered device that shows precision measurements and immunity to electromagnetic interference. Tested over a mid-high pressure range that shows a 20% improvement over the devices found in literature. This sensor is the result of the coupling of a multimode silica optical fiber, a MEMS pressure sensor with a thin silicon film and a stainless steel housing for packaging. A theoretical analysis and response simulations were used previous and along the process of construction and testing of the device. This analysis was followed by an assessment on the materials that were suitable for the assembling of the device, plus the pertinent modifications for each component that allowed a proper coupling. Several tests were done previous to the final assembly of the device, where calibration, alignment and limitations of the device were studied previous to determine the sensor's response. The experiments were done at the SimsLab of the University of Waterloo, using a pressure chamber with direct connection to the housing of the sensor to avoid pressure leaks. The sensor's properties include a silicon thin film with a thickness of 34 micrometers, an optical fiber with a core diameter of 125 micrometers, protected by a ceramic ferrule to provide stability and rigidity to the fiber. The fiber is part of a coupler that splits the optical signal between the input and output beams. The output leg of the coupler then sends the information to an OSI (Optical Sensor Interrogator) which is a set of electronics that use a photo detector to break the light into its spectral components, analyzing fringes and converting the photons into electrons which are digitized as a function of the wavelength and read out via a USB port into a host computer. A LabView program then converts the optical response to a value in millivolts that can be directly related to the changes in pressure that are detected by the deflective silicon membrane. A complete characterization of the sensor's response was carried out. An averaged sensitivity of 1.3768 mV / psi over a range of 0 - 100 psi was found. An accuracy of 1.25 psi per 0.1 mV was established. The Noise Equivalent Pressure measurement could to be neglected over the accuracy that is limited by the capacity of the electronics. In summary, an Optical MEMS pressure sensor was developed. This device is capable of being tested in laboratory and manufacturing-like simulated environments. The pressure measurements acquired during this project assisted the base for a future prototype to be developed in enhancing the pressure range in a harsh environment, with elevated temperature. Proof-of-concept data was gathered and analyzed so further advances can be reached on micro-fabrication and optical techniques.

Author:
Publisher:
ISBN:
Category : Aeronautics
Languages : en
Pages : 1026

View

Book Description
Lists citations with abstracts for aerospace related reports obtained from world wide sources and announces documents that have recently been entered into the NASA Scientific and Technical Information Database.

Author: Seyed Hamidreza Alemohammad
Publisher:
ISBN:
Category : Bragg gratings
Languages : en
Pages : 176

View

Book Description
The focus of this thesis is on the development of sensing devices based on optical fiber sensors, specifically optical Fiber Bragg Gratings (FBG), using laser microfabrication methods. FBG is a type of optical fibers whose spectral response is affected by applied strain and temperature. As a result, it can be calibrated for the measurement of physical parameters manifesting themselves in the changes of strain or temperature. The unique features of optical fiber sensors such as FBGs have encouraged the widespread use of the sensor and the development of optical fiber-based sensing devices for structural measurements, failure diagnostics, thermal measurements, pressure monitoring, etc. These features include light weight, small size, long-term durability, robustness to electromagnetic disturbances, and resistance to corrosion. Despite the encouraging features, there are some limitations and challenges associated with FBGs and their applications. One of the challenges associated with FBGs is the coupling of the effects of strain and temperature in the optical response of the sensors which affects the reliability and accuracy of the measurements. Another limitation of FBGs is insensitivity to the index of refraction of their surrounding medium. In liquids, the index of refraction is a function of concentration. Making FBGs sensitive to the index of refraction and keeping their thermal sensitivity intact enable optical sensors with the capability of the simultaneous measurement of concentration and temperature in liquids. Considering the unique features of FBGs, embedding of the sensors in metal parts for in-situ load monitoring is a cutting-edge research topic. Several industries such as machining tools, aerospace, and automotive industries can benefit from this technology. The metal embedding process is a challenging task, as the thermal decay of UV-written gratings can starts at a temperature of ~200 oC and accelerates at higher temperatures. As a result, the embedding process needs to be performed at low temperatures. The objective of the current thesis is to move forward the existing research front in the area of optical fiber sensors by finding effective solutions to the aforementioned limitations. The approaches consist of modeling, design, and fabrication of new FBG-based sensing devices. State-of-the-art laser microfabrication methods are proposed and implemented for the fabrication of the devices. Two approaches are adopted for the development of the FBG-based sensing devices: the additive method and the subtractive method. In both methods, laser direct microfabrication techniques are utilized. The additive method deals with the deposition of on-fiber metal thin films, and the subtractive method is based on the selective removal of materials from the periphery of optical fibers. To design the sensing devices and analyze the performance of the sensors, an opto-mechanical model of FBGs for thermal and structural monitoring is developed. The model is derived from the photo-elastic and thermo-optic properties of optical fibers. The developed model can be applied to predict the optical responses of a FBG exposed to structural loads and temperature variations with uniform and non-uniform distributions. The model is also extended to obtain optical responses of superstructure FBGs in which a secondary periodicity is induced in the index of refraction along the optical fiber. To address the temperature-strain coupling in FBGs, Superstructure FBGs (SFBG) with on-fiber metal thin films are designed and fabricated. It is shown that SFBGs have the capability of measuring strain and temperature simultaneously. The design of the sensor with on-fiber thin films is carried out by using the developed opto-mechanical model of FBGs. The performance of the sensor in concurrent measurement of strain and temperature is investigated by using a customized test rig. A laser-based Direct Write (DW) method, called Laser-Assisted Maskless Microdeposition (LAMM), is implemented to selectively deposit silver thin films on optical fibers and fabricate the superstructure FBGs. To attain thin films with premium quality, a characterization scheme is designed to study the geometrical, mechanical, and microstructural properties of the thin films in terms of the LAMM process parameters. A FBG, capable of measuring concentration and temperature of liquids is developed, and its performance is tested. Femtosecond laser micromachining is successfully implemented as a subtractive method for the sensor fabrication. For this purpose, periodic micro-grooves are inscribed in the cladding of regular FBGs so as to increase their sensitivity to the concentration of their surrounding liquid while keeping their thermal sensitivity intact. This type of sensors has the potential for applications in biomedical research, in which the in-situ measurement of the properties of biological analytes is required. Another accomplishment of this thesis is the development of FBG sensors embedded in metal parts for structural health monitoring using low temperature embedding processes. In this regard, the opto-mechanical model is extended to predict the optical response of the embedded FBGs. The embedding process involves low temperature casting, on-fiber thin film deposition, and electroplating methods. The performance of the embedded sensors is evaluated in structural loading and thermal cycling.

Author: National Research Council (U.S.). Transportation Research Board
Publisher: Transportation Research Board National Research
ISBN:
Category : Automatic data collection systems
Languages : en
Pages : 120

View

Book Description

Author: Lhaten
Publisher:
ISBN:
Category : Optical detectors
Languages : en
Pages : 83

View

Book Description

Author: Baoguo Han
Publisher: Butterworth-Heinemann
ISBN: 0128006587
Category : Technology & Engineering
Languages : en
Pages : 399

View

Book Description
Concrete is the second most used building material in the world after water. The problem is that over time the material becomes weaker. As a response, researchers and designers are developing self-sensing concrete which not only increases longevity but also the strength of the material. Self-Sensing Concrete in Smart Structures provides researchers and designers with a guide to the composition, sensing mechanism, measurement, and sensing properties of self-healing concrete along with their structural applications - Provides a systematic discussion of the structure of intrinsic self-sensing concrete - Compositions of intrinsic self-sensing concrete and processing of intrinsic self-sensing concrete - Explains the sensing mechanism, measurement, and sensing properties of intrinsic self-sensing concrete

Author: Mark D. Zoback
Publisher: Cambridge University Press
ISBN: 1107087074
Category : Business & Economics
Languages : en
Pages : 495

View

Book Description
A comprehensive overview of the key geologic, geomechanical and engineering principles that govern the development of unconventional oil and gas reservoirs. Covering hydrocarbon-bearing formations, horizontal drilling, reservoir seismology and environmental impacts, this is an invaluable resource for geologists, geophysicists and reservoir engineers.