WorldWideScience
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Fiber-Optic Sensing Technology  

Energy Technology Data Exchange (ETDEWEB)

This article offers a basic review of fiber-optic sensing technology, or more specifically, fiber-optic sensing technology as applied to the qualitative or quantitative identification of a chemical sample, and how it works,

Milnes, M. [Westinghouse Savannah River Company, AIKEN, SC (United States); Baylor, L.C.; Bave, S.

1996-10-24

2

Optical fiber rotation sensing  

CERN Document Server

Optical Fiber Rotation Sensing is the first book devoted to Interferometric Fiber Optic Gyros (IFOG). This book provides a complete overview of IFOGs, beginning with a historical review of IFOG development and including a fundamental exposition of basic principles, a discussion of devices and components, and concluding with industry reports on state-of-the-art activity. With several chapters contributed by principal developers of this solid-state device, the result is an authoritative work which will serve as the resource for researchers, students, and users of IFOGs.* * State-of-t

Burns, William K; Kelley, Paul

1993-01-01

3

Fiber optic sensing and imaging  

CERN Document Server

This book is designed to highlight the basic principles of fiber optic imaging and sensing devices. The editor has organized the book to provide the reader with a solid foundation in fiber optic imaging and sensing devices. It begins with an introductory chapter that starts from Maxwell’s equations and ends with the derivation of the basic optical fiber characteristic equations and solutions (i.e. fiber modes). Chapter 2 reviews most common fiber optic interferometric devices and Chapter 3 discusses the basics of fiber optic imagers with emphasis on fiber optic confocal microscope. The fiber optic interferometric sensors are discussed in detail in chapter 4 and 5. Chapter 6 covers optical coherence tomography and goes into the details of signal processing and systems level approach of the real-time OCT implementation. Also useful forms of device characteristic equations are provided so that this book can be used as a reference for scientists and engineers in the optics and related fields.

2013-01-01

4

Ultra Small Integrated Optical Fiber Sensing System  

OpenAIRE

This paper introduces a revolutionary way to interrogate optical fiber sensors based on fiber Bragg gratings (FBGs) and to integrate the necessary driving optoelectronic components with the sensor elements. Low-cost optoelectronic chips are used to interrogate the optical fibers, creating a portable dynamic sensing system as an alternative for the traditionally bulky and expensive fiber sensor interrogation units. The possibility to embed these laser and detector chips is demonstrated resulti...

Peter Van Daele; Kate Sugden; Webb, David J.; Oliver Maskery; Sandeep Kalathimekkad; Jeroen Missinne; Graham Lee; Erwin Bosman; Bram Van Hoe; Geert Van Steenberge

2012-01-01

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Ultra Small Integrated Optical Fiber Sensing System  

Directory of Open Access Journals (Sweden)

Full Text Available This paper introduces a revolutionary way to interrogate optical fiber sensors based on fiber Bragg gratings (FBGs and to integrate the necessary driving optoelectronic components with the sensor elements. Low-cost optoelectronic chips are used to interrogate the optical fibers, creating a portable dynamic sensing system as an alternative for the traditionally bulky and expensive fiber sensor interrogation units. The possibility to embed these laser and detector chips is demonstrated resulting in an ultra thin flexible optoelectronic package of only 40 ?m, provided with an integrated planar fiber pigtail. The result is a fully embedded flexible sensing system with a thickness of only 1 mm, based on a single Vertical-Cavity Surface-Emitting Laser (VCSEL, fiber sensor and photodetector chip. Temperature, strain and electrodynamic shaking tests have been performed on our system, not limited to static read-out measurements but dynamically reconstructing full spectral information datasets.

Peter Van Daele

2012-09-01

6

Fiber Optical Sensing with Fiber Bragg Gratings  

OpenAIRE

A new measurement method is presented utilizing glass fibers with inscribed Fiber Bragg Gratings (FBG). Strain and temperature changes have direct effects on these gratings. With this technology and suitable transducers, however, also parameters like pressure, dislocation, vibration, acceleration, humidity and even chemicals can be monitored. A broadband or sweeping laser light source is used and light with wavelengths corresponding to the FBGs is reflected back to a data acquisition unit (in...

 eisenmann, T.

2010-01-01

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Fiber optic nanoprobes for biological sensing  

Science.gov (United States)

Optical sensors have a large impact in the fields of life science research, drug discovery and medical diagnostics. The recent advances in nanotechnology and photonics have led to a new generation of nanotools, capable of probing even the single cell: it has already been demonstrated that nanobiosensors can detect biochemical targets and proteins inside living single cells. Here we provide a brief overview of the field of nanoprobes consisting of tapered, metal-coated optical fibers having nanosize tips, such as those which were originally developed for use in near-field optical microscopy. Moreover we present some preliminary results concerning the characterization of the experimental sensing system which exploits such nanoprobes for intracellular biomedical diagnostics. The feasibility of using the Fluorescence Lifetime Imaging Microscopy (FLIM) technique as a dynamic diagnostics tool with these nanoprobes has been demonstrated.

Barucci, Andrea; Berneschi, Simone; Cosi, Franco; Nunzi Conti, Gualtiero; Pelli, Stefano; Quercioli, Franco; Soria, Silvia; Righini, Giancarlo C.

2011-08-01

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Radiation distribution sensing with normal optical fiber  

International Nuclear Information System (INIS)

The purpose of this study is to develop a radiation distribution monitor using a normal plastic optical fiber. The monitor has a long operating length (10m-100m) and can obtain continuous radiation distributions. A principle of the position sensing is based on a time-of-flight technique. The characteristics of this monitor to beta particles, gamma rays and fast neutrons were obtained. The spatial resolutions for beta particles (90Sr-90Y), gamma rays (137Cs) and D-T neutrons were 30 cm, 37 cm and 13 cm, respectively. The detection efficiencies for the beta rays, the gamma rays and D-T neutrons were 0.11%, 1.6x10-5% and 5.4x10-4%, respectively. The effective attenuation length of the detection efficiency was 18m. New principle of the position sensing based on spectroscopic analysis was also proposed. A preliminary test showed that the spectrum observed at the end of the fiber depended on the position of the irradiated point. This fact shows that the radiation distributions were calculated from the spectrum by mathematical deconvolution technique. (author)

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Radiation distribution sensing with normal optical fiber  

CERN Document Server

The purpose of this study is to develop a radiation distribution monitor using a normal plastic optical fiber. The monitor has a long operating length (10m-100m) and can obtain continuous radiation distributions. A principle of the position sensing is based on a time-of-flight technique. The characteristics of this monitor to beta particles, gamma rays and fast neutrons were obtained. The spatial resolutions for beta particles ( sup 9 sup 0 Sr sup - sup 9 sup 0 Y), gamma rays ( sup 1 sup 3 sup 7 Cs) and D-T neutrons were 30 cm, 37 cm and 13 cm, respectively. The detection efficiencies for the beta rays, the gamma rays and D-T neutrons were 0.11%, 1.6x10 sup - sup 5 % and 5.4x10 sup - sup 4 %, respectively. The effective attenuation length of the detection efficiency was 18m. New principle of the position sensing based on spectroscopic analysis was also proposed. A preliminary test showed that the spectrum observed at the end of the fiber depended on the position of the irradiated point. This fact shows that t...

Kawarabayashi, J; Naka, R; Uritani, A; Watanabe, K I; Iguchi, T; Tsujimura, N

2002-01-01

10

Advanced fiber optical chemical sensing networks  

International Nuclear Information System (INIS)

Many industrial processes or other phenomena of interest cannot be measured with conventional instruments because they are too hot, too cold, highly radioactive, or otherwise inaccessible to direct observation. Nuclear wastes stored in underground repositories, for example, will require in-situ monitoring. A new technology that uses long-distance fiber optics to transmit laser-excited fluorescence now makes it possible to remotely monitor such phenomena via optical cables at distances up to a kilometer. The basic system consists of a laser light source, a Raman-fluorescence scattering spectrometer, and an optical fiber linked to a measuring device at the other end. Laser-generated light passes through an aperture and is focused on the end of the optical fiber by a geometric beam splitter. The light passes through the fiber, interacts with the sample to be measured, and returns (now incoherent), where it is reflected by a mirror into the computerized spectrometer for analysis

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Fiber-Optic Sensing for In-Space Inspection  

Science.gov (United States)

This presentation provides examples of fiber optic sensing technology development activities performed at NASA Armstrong. Examples of current and previous work that support in-space inspection techniques and methodologies are highlighted.

Pena, Francisco; Richards, W. Lance; Piazza, Anthony; Parker, Allen R.; Hudson, Larry D.

2014-01-01

12

Optical Fiber Sensing Based on Reflection Laser Spectroscopy  

Directory of Open Access Journals (Sweden)

Full Text Available An overview on high-resolution and fast interrogation of optical-fiber sensors relying on laser reflection spectroscopy is given. Fiber Bragg-gratings (FBGs and FBG resonators built in fibers of different types are used for strain, temperature and acceleration measurements using heterodyne-detection and optical frequency-locking techniques. Silica fiber-ring cavities are used for chemical sensing based on evanescent-wave spectroscopy. Various arrangements for signal recovery and noise reduction, as an extension of most typical spectroscopic techniques, are illustrated and results on detection performances are presented.

Gianluca Gagliardi

2010-03-01

13

Fiber Optic Wing Shape Sensing on NASA's Ikhana UAV  

Science.gov (United States)

This document discusses the development of fiber optic wing shape sensing on NASA's Ikhana vehicle. The Dryden Flight Research Center's Aerostructures Branch initiated fiber-optic instrumentation development efforts in the mid-1990s. Motivated by a failure to control wing dihedral resulting in a mishap with the Helios aircraft, new wing displacement techniques were developed. Research objectives for Ikhana included validating fiber optic sensor measurements and real-time wing shape sensing predictions; the validation of fiber optic mathematical models and design tools; assessing technical viability and, if applicable, developing methodology and approaches to incorporate wing shape measurements within the vehicle flight control system; and, developing and flight validating approaches to perform active wing shape control using conventional control surfaces and active material concepts.

Richards, Lance; Parker, Allen R.; Ko, William L.; Piazza, Anthony

2008-01-01

14

Magnetic Sensing with Ferrofluid and Fiber Optic Connectors  

OpenAIRE

A simple, cost effective and sensitive fiber optic magnetic sensor fabricated with ferrofluid and commercially available fiber optic components is described in this paper. The system uses a ferrofluid infiltrated extrinsic Fabry-Perot interferometer (EFPI) interrogated with an infrared wavelength spectrometer to measure magnetic flux density. The entire sensing system was developed with commercially available components so it can be easily and economically reproduced in large quantities. The ...

Daniel Homa; Gary Pickrell

2014-01-01

15

Optical Fiber Sensing Using Quantum Dots  

OpenAIRE

Recent advances in the application of semiconductor nanocrystals, or quantum dots, as biochemical sensors are reviewed. Quantum dots have unique optical properties that make them promising alternatives to traditional dyes in many luminescence based bioanalytical techniques. An overview of the more relevant progresses in the application of quantum dots as biochemical probes is addressed. Special focus will be given to configurations where the sensing dots are incorporated in sol...

Faramarz Farahi; José Luís Santos; Tito Trindade; Manuel António Martins; Pedro Jorge

2007-01-01

16

Photoinduced Electron Transfer Based Ion Sensing within an Optical Fiber  

Directory of Open Access Journals (Sweden)

Full Text Available We combine suspended-core microstructured optical fibers with the photoinduced electron transfer (PET effect to demonstrate a new type of fluorescent optical fiber-dip sensing platform for small volume ion detection. A sensor design based on a simple model PET-fluoroionophore system and small core microstructured optical fiber capable of detecting sodium ions is demonstrated. The performance of the dip sensor operating in a high sodium concentration regime (925 ppm Na+ and for lower sodium concentration environments (18.4 ppm Na+ is explored and future approaches to improving the sensor’s signal stability, sensitivity and selectivity are discussed.

Tanya M. Monro

2011-10-01

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Multiparameter fiber optic sensing system for monitoring enhanced geothermal systems  

Energy Technology Data Exchange (ETDEWEB)

The goal of this project was to design, fabricate and test an optical fiber cable which supports multiple sensing modalities for measurements in the harsh environment of enhanced geothermal systems. To accomplish this task, optical fiber was tested at both high temperatures and strains for mechanical integrity, and in the presence of hydrogen for resistance to darkening. Both single mode (SM) and multimode (MM) commercially available optical fiber were identified and selected for the cable based on the results of these tests. The cable was designed and fabricated using a tube-within-tube construction containing two MM fibers and one SM fiber, and without supporting gel that is not suitable for high temperature environments. Commercial fiber optic sensing instruments using Raman DTS (distributed temperature sensing), Brillouin DTSS (distributed temperature and strain sensing), and Raleigh COTDR (coherent optical time domain reflectometry) were selected for field testing. A microelectromechanical systems (MEMS) pressure sensor was designed, fabricated, packaged, and calibrated for high pressure measurements at high temperatures and spliced to the cable. A fiber Bragg grating (FBG) temperature sensor was also spliced to the cable. A geothermal well was selected and its temperature and pressure were logged. The cable was then deployed in the well in two separate field tests and measurements were made on these different sensing modalities. Raman DTS measurements were found to be accurate to ���±5���°C, even with some residual hydrogen darkening. Brillouin DTSS measurements were in good agreement with the Raman results. The Rayleigh COTDR instrument was able to detect some acoustic signatures, but was generally disappointing. The FBG sensor was used to determine the effects of hydrogen darkening, but drift over time made it unreliable as a temperature or pressure sensor. The MEMS sensor was found to be highly stable and accurate to better than its 0.1% calibration.

William A. Challener

2014-12-04

18

Distributed fiber optic moisture intrusion sensing system  

Science.gov (United States)

Method and system for monitoring and identifying moisture intrusion in soil such as is contained in landfills housing radioactive and/or hazardous waste. The invention utilizes the principle that moist or wet soil has a higher thermal conductance than dry soil. The invention employs optical time delay reflectometry in connection with a distributed temperature sensing system together with heating means in order to identify discrete areas within a volume of soil wherein temperature is lower. According to the invention an optical element and, optionally, a heating element may be included in a cable or other similar structure and arranged in a serpentine fashion within a volume of soil to achieve efficient temperature detection across a large area or three dimensional volume of soil. Remediation, moisture countermeasures, or other responsive action may then be coordinated based on the assumption that cooler regions within a soil volume may signal moisture intrusion where those regions are located.

Weiss, Jonathan D. (Albuquerque, NM)

2003-06-24

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Fiber sensing system based on a bragg grating and optical time domain reflectometry  

OpenAIRE

Optic fiber sensor characterized in that the sensing fiber is provided with a continuous Bragg grating covering the entire fiber length which is dedicated to sensing and along which spatially resolved measurements are performed.

Chin, Sanghoon; The?venaz, Luc

2013-01-01

20

Fiber optic shape sensing for monitoring of flexible structures  

Science.gov (United States)

Recent advances in materials science have resulted in a proliferation of flexible structures for high-performance civil, mechanical, and aerospace applications. Large aspect-ratio aircraft wings, composite wind turbine blades, and suspension bridges are all designed to meet critical performance targets while adapting to dynamic loading conditions. By monitoring the distributed shape of a flexible component, fiber optic shape sensing technology has the potential to provide valuable data during design, testing, and operation of these smart structures. This work presents a demonstration of such an extended-range fiber optic shape sensing technology. Three-dimensional distributed shape and position sensing is demonstrated over a 30m length using a monolithic silica fiber with multiple optical cores. A novel, helicallywound geometry endows the fiber with the capability to convert distributed strain measurements, made using Optical Frequency-Domain Reflectometry (OFDR), to a measurement of curvature, twist, and 3D shape along its entire length. Laboratory testing of the extended-range shape sensing technology shows

Lally, Evan M.; Reaves, Matt; Horrell, Emily; Klute, Sandra; Froggatt, Mark E.

2012-04-01

21

Fiber distributed Brillouin sensing with optical correlation domain techniques  

Science.gov (United States)

Fiber distributed Brillouin sensing is discussed, focusing mainly on optical correlation domain techniques. By synthesizing a delta-function like optical coherence function between pump and probe lightwave traveling along an optical fiber in opposite directions, which is realized by modulating laser source frequency by an appropriate waveform, stimulated Brillouin scattering can be selectively excited at one specific position along the fiber. The selected position can easily be swept by changing the modulation frequency, so the distributed measurement can be achieved. In the system, Brillouin Optical Correlation Domain Analysis (BOCDA), the position to be measured can be selected randomly along the fiber, which is a special feature of the system. Spatial resolution of 1.6 mm and measurement speed of 1000 samples/s have already been demonstrated. With a similar way, distribution of spontaneous Brillouin scattering can also be measured along the fiber. Spatial resolution of 10 mm and measurement speed of 50 samples/s have already been demonstrated in the system, Brillouin Optical Correlation Domain Reflectometry (BOCDR). Brillouin dynamic grating (BDG), which is acoustic-wave generated refractive-index grating caused in the stimulated Brillouin scattering process, was found to cause a Bragg reflection for the orthogonally polarized lightwave in an polarization maintaining fiber. By measuring both the BDG and the Brillouin scattering, discriminative distributed measurement of strain and temperature has been realized by the BOCDA scheme with a 10 mm spatial resolution.

Hotate, Kazuo

2013-12-01

22

Distributed Fiber Optic Gas Sensing for Harsh Environment  

Energy Technology Data Exchange (ETDEWEB)

This report summarizes work to develop a novel distributed fiber-optic micro-sensor that is capable of detecting common fossil fuel gases in harsh environments. During the 32-month research and development (R&D) program, GE Global Research successfully synthesized sensing materials using two techniques: sol-gel based fiber surface coating and magnetron sputtering based fiber micro-sensor integration. Palladium nanocrystalline embedded silica matrix material (nc-Pd/Silica), nanocrystalline palladium oxides (nc-PdO{sub x}) and palladium alloy (nc-PdAuN{sub 1}), and nanocrystalline tungsten (nc-WO{sub x}) sensing materials were identified to have high sensitivity and selectivity to hydrogen; while the palladium doped and un-doped nanocrystalline tin oxide (nc-PdSnO{sub 2} and nc-SnO{sub 2}) materials were verified to have high sensitivity and selectivity to carbon monoxide. The fiber micro-sensor comprises an apodized long-period grating in a single-mode fiber, and the fiber grating cladding surface was functionalized by above sensing materials with a typical thickness ranging from a few tens of nanometers to a few hundred nanometers. GE found that the morphologies of such sensing nanomaterials are either nanoparticle film or nanoporous film with a typical size distribution from 5-10 nanometers. nc-PdO{sub x} and alloy sensing materials were found to be highly sensitive to hydrogen gas within the temperature range from ambient to 150 C, while nc-Pd/Silica and nc-WO{sub x} sensing materials were found to be suitable to be operated from 150 C to 500 C for hydrogen gas detection. The palladium doped and un-doped nc-SnO{sub 2} materials also demonstrated sensitivity to carbon monoxide gas at approximately 500 C. The prototyped fiber gas sensing system developed in this R&D program is based on wavelength-division-multiplexing technology in which each fiber sensor is identified according to its transmission spectra features within the guiding mode and cladding modes. The interaction between the sensing material and fossil fuel gas results in a refractive index change and optical absorption in the sensing layer. This induces mode coupling strength and boundary conditions changes and thereby shifts the central wavelengths of the guiding mode and cladding modes propagation. GE's experiments demonstrated that such an interaction between the fossil fuel gas and sensing material not only shifts the central wavelengths of the guide mode and cladding modes propagation, but also alters their power loss characteristics. The integrated fiber gas sensing system includes multiple fiber gas sensors, fiber Bragg grating-based temperature sensors, fiber optical interrogator, and signal processing software.

Juntao Wu

2008-03-14

23

Distributed fiber optic sensing enhances pipeline safety and security  

Energy Technology Data Exchange (ETDEWEB)

Pipelines are efficient, highly reliable and safe means of transportation. However, despite intensive right of way surveillance by foot, car and out of the air, pipeline leaks and illegal tappings are a reality - sometimes with catastrophic results. These events show a gap in real-time monitoring caused by the highly distributed nature of pipelines. Parts of this gap now can be closed with distributed fiber optic sensing technology. Using various physical effects this technology is apt to detect temperature, strain, vibrations and sound with very good localization over spans up to 50 km with a single sensor cable. Various field tested applications like leakage detection, third party activity monitoring and intrusion detection or ground movement detection as well as integrity monitoring proof that distributed fiber optic sensing can enhance pipeline safety and security. (orig.)

Frings, Jochen; Walk, Tobias [ILF Consulting Engineers, Munich (Germany)

2011-09-15

24

Melamine sensing based on evanescent field enhanced optical fiber sensor  

Science.gov (United States)

Melamine is an insalubrious chemical, and has been frequently added into milk products illegally, to make the products more protein-rich. However, it can cause some various diseases, such as kidney stones and bladder cancer. In this paper, a novel optical fiber sensor with high sensitivity based on absorption of the evanescent field for melamine detection is successfully proposed and developed. Different concentrations of melamine changing from 0 to 10mg/mL have been detected using the micro/nano-sensing fiber decorated with silver nanoparticles cluster layer. As the concentration increases, the sensing fiber's output intensity gradually deceases and the absorption of the analyte becomes large. The concentration changing of 1mg/ml can cause the absorbance varying 0.664 and the limit of the melamine detectable concentration is 1ug/mL. Besides, the coupling properties between silver nanoparticles have also been analyzed by the FDTD method. Overall, this evanescent field enhanced optical fiber sensor has potential to be used in oligo-analyte detection and will promote the development of biomolecular and chemical sensing applications.

Luo, Ji; Yao, Jun; Wang, Wei-min; Zhuang, Xu-ye; Ma, Wen-ying; Lin, Qiao

2013-08-01

25

Novel long-distance fiber-optic sensing systems based on random fiber lasers  

Science.gov (United States)

The novel concept of utilizing a random fiber laser (RFL) to extend the sensing distance of fiber-optic sensing systems is proposed for the first time to our knowledge. In this paper, two schemes based on the RFL with a fiber Bragg grating (FBG) are experimentally demonstrated to verify the concept. The first one is a 100km FBG temperature sensing system, in which a 100km RFL provides an effective way to enhance the sensing signal of the FBG sensor due to its strong lasing radiation across the 100km fiber span. It is the first time to find that the RFL without the FBG is a temperatureinsensitive distributed lasing cavity, which offers stable long-distance transmission for the sensing signal. The second one is a 100km Brilloiun optical time domain analyzer (BOTDA), in which the generated random lasing is used as a fully distributed Raman pump and hence stable Raman amplification can be obtained to enhance the Brilloiun sensing signal. In principle, such a novel concept can be adopted for any type of distributed fiber-optic sensors as the RFL can be used as a stable distributed Raman pump for sensing signal amplification along the whole length of the fiber.

Wang, Zinan; Jia, Xinhong; Rao, Yunjiang; Jiang, Yun; Zhang, Weili

2012-02-01

26

Liquid Seal for Temperature Sensing with Fiber-Optic Refractometers  

Directory of Open Access Journals (Sweden)

Full Text Available Liquid sealing is an effective method to convert a fiber-optic refractometer into a simple and highly sensitive temperature sensor. A refractometer based on the thin-core fiber modal interferometer is sealed in a capillary tube filled with Cargille oil. Due to the thermo-optic effect of the sealing liquid, the high refractive-index sensitivity refractometer is subsequently sensitive to the ambient temperature. It is found that the liquid-sealed sensor produces a highest sensitivity of ?2.30 nm/°C, which is over 250 times higher than its intrinsic sensitivity before sealing and significantly higher than that of a grating-based fiber sensors. The sensing mechanisms, including the incidental temperature-induced strain effect, are analyzed in detail both theoretically and experimentally. The liquid sealing technique is easy and low cost, and makes the sensor robust and insensitive to the surrounding refractive index. It can be applied to other fiber-optic refractometers for temperature sensing.

Ben Xu

2014-08-01

27

Optical fiber sensing technology in the pipeline industry  

Energy Technology Data Exchange (ETDEWEB)

This paper is concerned with applications of optical fiber sensors to pipeline monitoring. The basic principles of optical fiber sensors are briefly reviewed, with particular attention to fiber Bragg grating technology. Different potential applications in the pipeline industry are discussed, and an example of a pipeline strain monitoring system based on optical fiber Bragg grating sensors is presented. (author)

Braga, A.M.B.; Llerena, R.W.A. [Pontificia Univ. Catolica do Rio de Janeiro, RJ (Brazil). Dept. de Engenharia Mecanica]. E-mail: abraga@mec.puc-rio.br; roberan@mec.puc-rio.br; Valente, L.C.G.; Regazzi, R.D. [Gavea Sensors, Rio de Janeiro, RJ (Brazil)]. E-mail: guedes@gaveasensors.com; regazzi@gaveasensors.com

2003-07-01

28

Frequency-Shifted Interferometry — A Versatile Fiber-Optic Sensing Technique  

OpenAIRE

Fiber-optic sensing is a field that is developing at a fast pace. Novel fiber-optic sensor designs and sensing principles constantly open doors for new opportunities. In this paper, we review a fiber-optic sensing technique developed in our research group called frequency-shifted interferometry (FSI). This technique uses a continuous-wave light source, an optical frequency shifter, and a slow detector. We discuss the operation principles of several FSI implementations and show their applicati...

Fei Ye; Yiwei Zhang; Bing Qi; Li Qian

2014-01-01

29

Brillouin scattering accompanied by acoustic grating in an optical fiber and applications in fiber distributed sensing  

Science.gov (United States)

Fiber optic distributed sensing systems based on Brillouin scattering are reviewed. Strain or temperature distribution along an optical fiber can be measured with this phenomenon using time domain and correlation domain techniques. Superior functions have already been demonstrated, such as mm order spatial resolution and kHz order measurement speed. Brillouin scattering is accompanied by acoustic grating, which is generated by thermal vibration of fiber material. Recently, considering the nature of the acoustic grating enhanced through stimulated Brillouin scattering process, various advanced functions have been realized in the distributed sensing, such as discriminative measurement of strain and temperature with a 10 cm resolution by a correlation domain technique, realization of cm order resolution by a time domain technique, and distributed birefringence measurement along a polarization maintaining fiber. These Brillouin based systems are also compared briefly with FBG based systems, including distributed sensing with long-length FBG.

Hotate, Kazuo

2011-05-01

30

Sensing principle of fiber-optic curvature sensor  

Science.gov (United States)

A novel fiber-optic sensor, which can measure curvature directly, has been developed in recent years. Its curvature measurement sensitivity is improved by a sensitive zone. To better understand the working principle and improve the performance of the sensor, the ray tracing simulation was carried out by using optical analysis software TracePro, which provides the sensing process for us. The results show that the rays will concentrate to the convex side of bent fiber. That is, the light intensity will increase at convex side and decrease at concave side, which leads to the changes of light leakage at sensitive zone and realizes the modulation to light intensity. The mathematic model of relationship among light loss, parameters of sensitive zone's configuration and bending curvature is presented.

Di, Haiting

2014-10-01

31

Frequency-shifted interferometry for fiber-optic sensing  

Science.gov (United States)

This thesis studies frequency-shifted interferometry (FSI), a useful and versatile technique for fiber-optic sensing. I first present FSI theory by describing practical FSI configurations and discussing the parameters that affect system performance. Then, I demonstrate the capabilities of FSI in fiber-optic sensor multiplexing and high sensitivity chemical analysis. We implemented a cryogenic liquid level sensing system in which an array of 3 fiber Bragg grating (FBG) based sensors was interrogated by FSI. Despite sensors' spectral overlap, FSI is able to separate sensor signals according to their spatial locations and to measure their spectra, from which whether a sensor is in liquid or air can be unambiguously determined. I showed that a broadband source paired with a fast tunable filter can be used in FSI systems as the light source. An array of 9 spectrally overlapping FBGs was successfully measured by such a system, indicating the potential of system cost reduction as well as measurement speed improvement. I invented the the FSI-CRD technique, a highly sensitive FSI-based fiber cavity ring-down (CRD) method capable of deducing minuscule loss change in a fiber cavity from the intensity decay rate of continuous-wave light circulating in the cavity. As a proof-of-principle experiment, I successfully measured the fiber bend loss introduced in the fiber cavity with FSI-CRD, which was found to be 0.172 dB/m at a bend radius of 12.5 mm. We then applied FSI-CRD to evanescent-field sensing. We incorporated fiber tapers as the sensor head in the system and measured the concentration of 1-octyne solutions. A minimum detectable 1-octyne concentration of 0.29% was achieved with measurement sensitivity of 0.0094 dB/% 1-octyne. The same system also accurately detected the concentration change of sodium chloride (NaCl) and glucose solutions. Refractive index sensitivity of 1 dB/RIU with a measurement error of 1x10-4 dB was attined for NaCl solutions. Finally, I proposed a theoretical model to study the polarization effects in FSI systems. Preliminary results show that the model can already explain the experimental observations. It not only provides insight into how to improve system performance but also suggests potential new applications of the technique.

Ye, Fei

32

Calibration and Deployment of a Fiber-Optic Sensing System for Monitoring Debris Flows  

OpenAIRE

This work presents a novel fiber-optic sensing system, capable of monitoring debris flows or other natural hazards that produce ground vibrations. The proposed sensing system comprises a demodulator (BraggSCOPE, FS5500), which includes a broadband light source and a data logger, a four-port coupler and four Fiber Bragg Grating (FBG) accelerometers. Based on field tests, the performance of the proposed fiber-optic sensing system is compared with that of a conventional sensing system that inclu...

Tsung-Mo Tien; Hsiao-Yuen Yin; Ping-Sen Chen; Ching-Jer Huang; Chung-Ray Chu

2012-01-01

33

Extreme temperature sensing using brillouin scattering in optical fibers  

CERN Document Server

Stimulated Brillouin scattering in silica-based optical fibers may be considered from two different and complementary standpoints. For a physicist, this interaction of light and pressure wave in a material, or equivalently in quantum theory terms between photons and phonons, gives some glimpses of the atomic structure of the solid and of its vibration modes. For an applied engineer, the same phenomenon may be put to good use as a sensing mechanism for distributed measurements, thanks to the dependence of the scattered light on external parameters such as the temperature, the pressure or the strain applied to the fiber. As far as temperature measurements are concerned, Brillouin-based distributed sensors have progressively gained wide recognition as efficient systems, even if their rather high cost still restricts the number of their applications. Yet they are generally used in a relatively narrow temperature range around the usual ambient temperature; in this domain, the frequency of the scattered light incre...

Fellay, Alexandre

34

Analyzing Fourier Transforms for NASA DFRC's Fiber Optic Strain Sensing System  

Science.gov (United States)

This document provides a basic overview of the fiber optic technology used for sensing stress, strain, and temperature. Also, the document summarizes the research concerning speed and accuracy of the possible mathematical algorithms that can be used for NASA DFRC's Fiber Optic Strain Sensing (FOSS) system.

Fiechtner, Kaitlyn Leann

2010-01-01

35

Magnetic Sensing with Ferrofluid and Fiber Optic Connectors  

Directory of Open Access Journals (Sweden)

Full Text Available A simple, cost effective and sensitive fiber optic magnetic sensor fabricated with ferrofluid and commercially available fiber optic components is described in this paper. The system uses a ferrofluid infiltrated extrinsic Fabry-Perot interferometer (EFPI interrogated with an infrared wavelength spectrometer to measure magnetic flux density. The entire sensing system was developed with commercially available components so it can be easily and economically reproduced in large quantities. The device was tested with two different ferrofluid types over a range of magnetic flux densities to verify performance. The sensors readily detected magnetic flux densities in the range of 0.5 mT to 12.0 mT with measurement sensitivities in the range of 0.3 to 2.3 nm/mT depending on ferrofluid type. Assuming a conservative wavelength resolution of 0.1 nm for state of the art EFPI detection abilities, the estimated achievable measurement resolution is on the order 0.04 mT. The inherent small size and basic structure complimented with the fabrication ease make it well-suited for a wide array of research, industrial, educational and military applications.

Daniel Homa

2014-02-01

36

Magnetic sensing with ferrofluid and fiber optic connectors.  

Science.gov (United States)

A simple, cost effective and sensitive fiber optic magnetic sensor fabricated with ferrofluid and commercially available fiber optic components is described in this paper. The system uses a ferrofluid infiltrated extrinsic Fabry-Perot interferometer (EFPI) interrogated with an infrared wavelength spectrometer to measure magnetic flux density. The entire sensing system was developed with commercially available components so it can be easily and economically reproduced in large quantities. The device was tested with two different ferrofluid types over a range of magnetic flux densities to verify performance. The sensors readily detected magnetic flux densities in the range of 0.5 mT to 12.0 mT with measurement sensitivities in the range of 0.3 to 2.3 nm/mT depending on ferrofluid type. Assuming a conservative wavelength resolution of 0.1 nm for state of the art EFPI detection abilities, the estimated achievable measurement resolution is on the order 0.04 mT. The inherent small size and basic structure complimented with the fabrication ease make it well-suited for a wide array of research, industrial, educational and military applications. PMID:24573312

Homa, Daniel; Pickrell, Gary

2014-01-01

37

Microstructure of the smart composite structures with embedded fiber optic sensing nerves  

Science.gov (United States)

The composite structures with embedded optical fiber sensors construct a smart composite structure system, which may have the characteristics of the in-service self-measurement, self- recognition and self-judgement action. In the present work, we studied the microstructures of carbon/epoxy composite laminates with embedded sensing optical fibers, and the integration of optical fiber with composites was also discussed. The preliminary experiment results show that because of the difference between the sensing optical fibers and the reinforcing fibers in their size, the microstructure of the composites with embedded optical fibers will produce partial local changes in the area of embedded optical fiber, these changes may affect the mechanical properties of composite structures. When the optical fibers are embedded parallel to the reinforcing fibers, due to the composite prepregs are formed under a press action during its curing process, the reinforcing fibers can be arranged equably around the optical fibers. But when the optical fibers are embedded perpendicularly to the reinforcement fibers, the resin rich pocket will appear in the composite laminates surrounding the embedded optical fiber. The gas holes will be easily produced in these zones which may produce a premature failure of the composite structure. The photoelastic experiments are also given in the paper.

Liu, Jingyuan; Luo, Fei; Li, Changchun; Ma, Naibin

1997-11-01

38

Perfluorinated Plastic Optical Fiber Tapers for Evanescent Wave Sensing  

Directory of Open Access Journals (Sweden)

Full Text Available In this work we describe the fabrication and the characterization of perfluorinated plastic-cladded optical fiber tapers. The heat-and-pull procedure has been used to fabricate symmetric tapers. Devices with different taper ratio have been produced and the repeatability of the process has been verified. The very low refractive indexes of the core-cladding perfluorinated polymers (n = 1.35–1.34 permit a strong enhancement of the evanescent wave power fraction in aqueous environments (n = 1.33, making them very attractive for evanescent wave sensing. The tapers have been characterized carrying out evanescent field absorbance measurements with different concentrations of methylene blue in water and fluorescence collection measurements in an aqueous solution containing Cy5 dye. A good sensitivity, tightly related to the low refractive index of the core-cladding materials and the geometrical profile, has been shown.

Romeo Bernini

2009-12-01

39

Frequency-Shifted Interferometry — A Versatile Fiber-Optic Sensing Technique  

Directory of Open Access Journals (Sweden)

Full Text Available Fiber-optic sensing is a field that is developing at a fast pace. Novel fiber-optic sensor designs and sensing principles constantly open doors for new opportunities. In this paper, we review a fiber-optic sensing technique developed in our research group called frequency-shifted interferometry (FSI. This technique uses a continuous-wave light source, an optical frequency shifter, and a slow detector. We discuss the operation principles of several FSI implementations and show their applications in fiber length and dispersion measurement, locating weak reflections along a fiber link, fiber-optic sensor multiplexing, and high-sensitivity cavity ring-down measurement. Detailed analysis of FSI system parameters is also presented.

Fei Ye

2014-06-01

40

Expanding the realm of fiber optic confocal sensing for probing position, displacement, and velocity  

International Nuclear Information System (INIS)

We describe a fiber optic confocal sensor (FOCOS) system that uses an optical fiber and a lens to accurately detect the position of an object at, or close to, the image plane of the fiber tip. The fiber characteristics (diameter and numerical aperture) and optics (lens F and magnification) define the span and precision of the sensor and may be chosen to fit a desired application of position and displacement sensing. Multiple measurement points (i.e., fiber-tip images) may be achieved by use of multiple wavelengths in the fiber, so that each wavelength images the fiber at a different plane due to the chromatic dispersion of the optics. Further multiplexing may be achieved by adding fibers on the optical axis. A FOCOS with multiplexed fibers and wavelengths may also be used for velocity measurements

41

Distributed fiber optical sensing of oxygen with optical time domain reflectometry.  

Science.gov (United States)

In many biological and environmental applications spatially resolved sensing of molecular oxygen is desirable. A powerful tool for distributed measurements is optical time domain reflectometry (OTDR) which is often used in the field of telecommunications. We combine this technique with a novel optical oxygen sensor dye, triangular-[4] phenylene (TP), immobilized in a polymer matrix. The TP luminescence decay time is 86 ns. The short decay time of the sensor dye is suitable to achieve a spatial resolution of some meters. In this paper we present the development and characterization of a reflectometer in the UV range of the electromagnetic spectrum as well as optical oxygen sensing with different fiber arrangements. PMID:23727953

Eich, Susanne; Schmälzlin, Elmar; Löhmannsröben, Hans-Gerd

2013-01-01

42

Optical fiber sensing in the oil and gas industry: overcoming challenges  

Science.gov (United States)

Optical fiber sensors have evolved to withstand many operational challenges?including high temperatures, extreme pressures, and excessive hydrogen levels?in harsh environments. Advances in fiber design and sensing techniques have helped to build rugged and reliable sensing architectures. This paper provides an overview of improvements and technical achievements over the past two decades.

Baldwin, Christopher

2014-05-01

43

Fiber Optic Sensing Systems and their Possible Application as Safeguards Monitoring Tools  

International Nuclear Information System (INIS)

The availability of appropriate operational-safety-related monitoring devices and systems is a major challenge in radioactive waste disposal. For several years, fiber-optic sensing devices had been used for straightforward on/off monitoring functions such as presence and position detection. Recently, they gained interest as they offer a novel, exciting technology for a multitude of sensing applications. In the deep geological environment most physical parameters important to safety can be measured with fiber-optic systems. DBE TECHNOLOGY is developing and testing in-situ monitoring devices based on fiber-optic technology as the basis for monitoring systems at the German underground final repositories. The possibility of distributed sensing along an optical fiber and the ability of coupling several fibers in a large sensing network are key elements of this technology development effort. Results hitherto achieved have proven the suitability in principle of this technology, and are very promising with regard to their wide applicability and purposefulness

44

Fiber-optic-coupled dosemeter for remote optical sensing of radiation  

International Nuclear Information System (INIS)

Remote sensing technologies for the detection and measurement of ionizing radiation exposure are of current interest for applications such as patient dose verification during radiotherapy and the monitoring of environmental contaminants. Fiberoptic-based sensing is attractive due to the advantages of small size, low cost, long life and freedom from electromagnetic interference. Several fiberoptic-based radiation sensing systems have been described that utilize radiation induced changes in the optical characteristics of the fiber such as reduced transmission as a result of darkening of the glass, optical phase shifts due to heating, or changes in the birefringence of a polarization-maintaining fiber. The measurement of radiation induced darkening is limited in both sensitivity and dynamic range and requires long fiber lengths. Phase shift measurements require the use of single-mode lasers, phase sensitive interferometric detection, long fiber lengths and complex signal processing techniques. Alternatively, thermoluminescent (TL) phosphor powders have been coated onto fiberoptic cables and remote dosimetry measurements performed using traditional laser heating techniques. The sensitivity is limited by the requirement for a very thin layer of phosphor material, due to problems associated with light scattering and efficient heating by thermal diffusion. In this paper we report the development of an all-optical, fiber-optic-coupled, thermoluminescence dosemeter for remote , thermoluminescence dosemeter for remote radiation sensing that offers significant advantages compared to previous technologies. We recently reported the development of an optically transparent, TL glass material having exceptionally good characteristics for traditional dosimetry applications. We also reported a modified TL glass incorporating a rare earth ion dopant in order to absorb light from a semiconductor laser and utilize the absorbed light energy to internally heat the glass and release the trapped electrons. (author)

45

Remote Management for Multipoint Sensing Systems Using Hetero-Core Spliced Optical Fiber Sensors  

Directory of Open Access Journals (Sweden)

Full Text Available This paper describes the design and experimental verification of a multipoint sensing system with hetero-core spliced optical fiber sensors and its remote management using an internet-standard protocol. The study proposes two different types of design and conducts experiments to verify those systems’ feasibility. In order to manage the sensing systems remotely, the management method uses a standard operation and maintenance protocol for internet: the Simple Network Management Protocol is proposed. The purpose of this study is to construct a multipoint sensing system remote management tool by which the system can also determine the status and the identity of fiber optic sensors. The constructed sensing systems are verified and the results have demonstrated that the first proposed system can distinguish the responses from different hetero-core spliced optical fiber sensors remotely. The second proposed system shows that data communications are performed successfully while identifying the status of hetero-core spliced optical fiber sensors remotely.

Lee See Goh

2013-12-01

46

Bragg grating fiber optic sensing for bridges and other structures  

Science.gov (United States)

We have demonstrated that fiber optic intracore Bragg grating sensors are able to measure the strain relief experienced over an extended period of time by both steel and carbon composite tendons within the concrete deck support girders of a recently constructed two span highway bridge. This is the first bridge in the world to test the prospects of using carbon fiber composite tendons to replace steel tendons. This unique set of measurements was accomplished with an array of 15 Bragg grating fiber optic sensors that were embedded within the precast concrete girders during their construction. We have also demonstrated that these same sensors can measure the change in the internal strain within the girders associated with both static and dynamic loading of the bridge with a truck. We are now studying the ability of Bragg grating fiber optic sensors to measure strong strain gradients and thereby provide a warning of debonding of any Bragg grating sensor from its host structure...one of the most important failure modes for any fiber optic strain sensor.

Measures, Raymond M.; Alavie, A. Tino; Maaskant, Robert; Huang, Shang Yuan; LeBlanc, Michel

1994-09-01

47

Liquid Seal for Temperature Sensing with Fiber-Optic Refractometers  

OpenAIRE

Liquid sealing is an effective method to convert a fiber-optic refractometer into a simple and highly sensitive temperature sensor. A refractometer based on the thin-core fiber modal interferometer is sealed in a capillary tube filled with Cargille oil. Due to the thermo-optic effect of the sealing liquid, the high refractive-index sensitivity refractometer is subsequently sensitive to the ambient temperature. It is found that the liquid-sealed sensor produces a highest sensitivity of ?2.30...

Ben Xu; Jianqing Li; Yi Li; Jianglei Xie; Xinyong Dong

2014-01-01

48

Validation of TW-COTDR method for 25km distributed optical fiber sensing  

Science.gov (United States)

The paper reports results of the long distance (25 km range) distributed optical fiber sensing by means of Tunable Wavelength Coherent Optical Time Domain Reflectometry (TW-COTDR) method. The tests were designed to verify the accuracy and repeatability of the method in long distance measurements, as well as compatibility with various optical fiber types. Results demonstrate the capability of the method to detect strain or temperature changes over long distances. This proposed method is compared to Brillouin sensing techniques, into the same fibers. Unlike the Brillouin-based methods, measurement uncertainty does not increase with increasing distance. We demonstrated 0.16°C uncertainty at 21km.

Delepine-Lesoille, Sylvie; Guzik, Artur; Bertrand, Johan; Henault, Jean-Marie; Kishida, Kinzo

2013-05-01

49

Fully distributed fiber-optic sensing based on acoustically induced long-period grating  

Science.gov (United States)

This paper gives a review of a proposed fully-distributed fiber-optic sensing technique based on a traveling long-period grating (LPG) in a single-mode optical fiber. The LPG is generated by pulsed acoustic waves that propagate along the fiber. Based on this platform, first we demonstrated the fully-distributed temperature measurement in a 2.5m fiber. Then by coating the fiber with functional coatings, we demonstrated fully-distributed biological and chemical sensing. In the biological sensing experiment, immunoglobulin G (IgG) was immobilized onto the fiber surface, and we showed that only specific antigen-antibody binding can introduce a measurable shift in the transmission optical spectrum of the traveling LPG when it passes through the pretreated fiber segment. In the hydrogen sensing experiment, the fiber was coated with a platinum (Pt) catalyst layer, which is heated by the thermal energy released from Pt-assisted combustion of H2 and O2, and the resulted temperature change gives rise to a measurable LPG wavelength shift when the traveling LPG passes through. Hydrogen concentration from 1% to 3.8% was detected in the experiment. This technique may also permit measurement of other quantities by changing the functional coating on the fiber; therefore it is expected to be capable of other fully-distributed sensing applications.

Wang, Dorothy Y.; Wang, Yunmiao; Han, Ming; Gong, Jianmin; Wang, Anbo

2011-05-01

50

Research On Fiber Optic Sensing Systems And Their Application As Final Repository Monitoring Tools  

International Nuclear Information System (INIS)

For several years, fiber-optic sensing devices had been used for straightforward on/off monitoring functions such as presence and position detection. Recently, they gained interest as they offer a novel, exciting technology for a multitude of sensing applications. In the deep geological environment most physical properties, and thus most parameters important to safety, can be measured with fiber-optic technology. Typical examples are displacements, strains, radiation dose and dose rate, presence of some gases, temperature, pressure, etc. Their robustness, immunity to electromagnetic interference, as well as their large bandwidths and data rates ensure high reliability and superior performance. Moreover, the networking capabilities of meanwhile available fiber-optic sensors allow for efficient management of large sensor systems. Distributed sensing with multiple sensing locations on a single fiber reduces significantly the number of cables and connecting points. Reliable, cost effective, and maintenance-free solutions can thus be implemented

51

Two-core optical fiber and its sensing characteristics  

Science.gov (United States)

Two-core fiber is a specially designed fiber which contains a pair of parallel fiber core surrounding a cladding with diameter 125?m. A multi-parameters measurement technique that uses a two-core fiber as the sensing element has been proposed and demonstrated in this paper. The theory and the structure design are also introduced. The two-core fiber acts as a two-beam interferometer, in which phase differences is a function of curvature, and the twisting angle in the plane containing the cores results in the shift of the far-field interferometric fringe pattern. This sensor can be used to inspect the structural health monitoring, the measuring angle and the distinguishing direction. Compared to the traditional multi-beam interferometer, this sensor has the such characteristics as small size, good interference, high definition and steady fringe pattern. It does not need considering the effect of the environment temperature. A low-coherence laser diode at wavelength 650nm illuminating the two-cores and the interferogram pattern in the far-field is recorded by a CCD camera. The model of two-core fiber sensor has been established theoretically. The relationship between the far-field fringe pattern intensity distribution and the changes due to the radius of the curvature and the twisting angle are given, and the experimental results also confirmed this.

Wang, Xue; Zhao, Shigang; Yuan, Libo

2007-11-01

52

Surface plasmon sensing of gas phase contaminants using optical fiber.  

Energy Technology Data Exchange (ETDEWEB)

Fiber-optic gas phase surface plasmon resonance (SPR) detection of several contaminant gases of interest to state-of-health monitoring in high-consequence sealed systems has been demonstrated. These contaminant gases include H{sub 2}, H{sub 2}S, and moisture using a single-ended optical fiber mode. Data demonstrate that results can be obtained and sensitivity is adequate in a dosimetric mode that allows periodic monitoring of system atmospheres. Modeling studies were performed to direct the design of the sensor probe for optimized dimensions and to allow simultaneous monitoring of several constituents with a single sensor fiber. Testing of the system demonstrates the ability to detect 70mTorr partial pressures of H{sub 2} using this technique and <280 {micro}Torr partial pressures of H{sub 2}S. In addition, a multiple sensor fiber has been demonstrated that allows a single fiber to measure H{sub 2}, H{sub 2}S, and H{sub 2}O without changing the fiber or the analytical system.

Thornberg, Steven Michael; White, Michael I.; Rumpf, Arthur Norman; Pfeifer, Kent Bryant

2009-10-01

53

Fiber-optic physical and biochemical sensing based on transient and traveling long-period gratings.  

Science.gov (United States)

A fiber-optic sensing platform based on a transient and traveling long-period grating (LPG) in a single-mode optical fiber has been proposed and demonstrated. The LPG is generated by pulsed acoustic waves that propagate along the fiber. First, we demonstrate the LPG for temperature measurement along the fiber. By coating the fiber with ultrathin ionically self-assembled multilayers, we then show that the LPG is capable of detecting nanometer thickness variations of the fiber. A temperature compensation method is also proposed and demonstrated. Because the acoustically generated LPG travels along the fiber, this advance is expected to yield a highly sensitive fully distributed fiber-optic biochemical sensor. PMID:19241631

Han, Ming; Wang, Yunjing; Wang, Yunmiao; Wang, Anbo

2009-01-01

54

Downhole fiber optic sensing: the oilfield service provider's perspective: from the cradle to the grave  

Science.gov (United States)

For almost three decades, interest has continued to increase with respect to the application of fiber-optic sensing techniques for the upstream oil and gas industry. This paper reviews optical sensing technologies that have been and are being adopted downhole, as well as their drivers. A brief description of the life of a well, from the cradle to the grave, and the roles fiber-optic sensing can play in optimizing production, safety, and protection of the environment are also presented. The performance expectations (accuracy, resolution, stability, and operational lifetime) that oil companies and oil service companies have for fiber-optic sensing systems is described. Additionally, the environmental conditions (high hydrostatic pressures, high temperatures, shock, vibration, crush, and chemical exposure) that these systems must tolerate to provide reliable and economically attractive oilfield monitoring solutions are described.

Skinner, Neal G.; Maida, John L.

2014-06-01

55

Research on distributed strain separation technology of fiber Brillouin sensing system combining an electric power optical fiber cable  

Science.gov (United States)

Brillouin-based optical fiber sensing system has been taken more and more attentions in power transmission line in recent years. However, there exists a temperature cross sensitivity problem in sensing system. Hence, researching on strain separation technology of fiber brillouin sensing system is an urgent requirement in its practical area. In this paper, a real-time online distributed strain separation calculation technology of fiber Brillouin sensing combining an electric power optical fiber cable is proposed. The technology is mainly composed of the Brillouin temperature-strain distributed measurement system and the Raman temperature distributed measurement system. In this technology, the electric power optical fiber cable is a special optical phase conductor (OPPC); the Brillouin sensing system uses the Brillouin optical time domain analysis (BOTDA) method. The optical unit of the OPPC includes single-mode and multimode fibers which can be used as sensing channel for Brillouin sensing system and Raman sensing system respectively. In the system networking aspect, the data processor of fiber Brillouin sensing system works as the host processor and the data processor of fiber Raman sensing system works as the auxiliary processor. And the auxiliary processor transfers the data to the host processor via the Ethernet interface. In the experiment, the BOTDA monitoring system and the Raman monitoring system work on the same optical unit of the OPPC simultaneously; In the data processing aspect, the auxiliary processor of Raman transfers the temperature data to the host processor of Brillouin via the Ethernet interface, and then the host processor of Brillouin uses the temperature data combining itself strain-temperature data to achieve the high sampling rate and high-precision strain separation via data decoupling calculation. The data decoupling calculation is achieved through the interpolation, filtering, feature point alignment, and the singular point prediction algorithm etc. Testing in the laboratory and the transmission line test base all show that the simultaneous temperature and strain distribution measurement system can work effectively and reliably. This system provides a good solution reference to solve the temperature cross sensitivity problem in Brillouin-based optical fiber sensing system, and demonstrate a great practical value in power system applications.

Lei, Yuqing; Chen, Xi; Li, Jihui; Tong, Jie

2013-12-01

56

Reflection based Extraordinary Optical Transmission Fiber Optic Probe for Refractive Index Sensing.  

Science.gov (United States)

Fiber optic probes for chemical sensing based on the extraordinary optical transmission (EOT) phenomenon are designed and fabricated by perforating subwavelength hole arrays on the gold film coated optical fiber endface. The device exhibits a red shift in response to the surrounding refractive index increases with high sensitivity, enabling a reflection-based refractive index sensor with a compact and simple configuration. By choosing the period of hole arrays, the sensor can be designed to operate in the near infrared telecommunication wavelength range, where the abundant source and detectors are available for easy instrumentation. The new sensor probe is demonstrated for refractive index measurement using refractive index matching fluids. The sensitivity reaches 573 nm/RIU in the 1.333~1.430 refractive index range. PMID:24574579

Lan, Xinwei; Cheng, Baokai; Yang, Qingbo; Huang, Jie; Wang, Hanzheng; Ma, Yinfa; Shi, Honglan; Xiao, Hai

2014-03-31

57

Distributed Fiber Optical Sensing of Oxygen with Optical Time Domain Reflectometry  

Directory of Open Access Journals (Sweden)

Full Text Available In many biological and environmental applications spatially resolved sensing of molecular oxygen is desirable. A powerful tool for distributed measurements is optical time domain reflectometry (OTDR which is often used in the field of telecommunications. We combine this technique with a novel optical oxygen sensor dye, triangular-[4] phenylene (TP, immobilized in a polymer matrix. The TP luminescence decay time is 86 ns. The short decay time of the sensor dye is suitable to achieve a spatial resolution of some meters. In this paper we present the development and characterization of a reflectometer in the UV range of the electromagnetic spectrum as well as optical oxygen sensing with different fiber arrangements.

Elmar Schmälzlin

2013-05-01

58

A lateral locating method for optical fiber distributed intrusion sensing system  

Science.gov (United States)

A lateral locating method is proposed and demonstrated in optical fiber distributed vibration sensing system based on phase-sensitive optical time domain reflectometer. The locating depends on a method of time difference of arrival to calculate the time difference between two sensing points. Through this method, we can get the vertical distance between the vibration source and the sensing fiber. Therefore, we can make sure the degree of danger of intrusion. The test results show that the locating accuracy is about 2.10 m with 100-MHz sampling rate, 1-kHz pulse repetition rate, and 1500 sampling points within one pulse interval.

Zhou, Zhengxian; Zhuang, Songlin

2014-12-01

59

Perfluorinated Plastic Optical Fiber Tapers for Evanescent Wave Sensing  

OpenAIRE

In this work we describe the fabrication and the characterization of perfluorinated plastic-cladded optical fiber tapers. The heat-and-pull procedure has been used to fabricate symmetric tapers. Devices with different taper ratio have been produced and the repeatability of the process has been verified. The very low refractive indexes of the core-cladding perfluorinated polymers (n = 1.35–1.34) permit a strong enhancement of the evanescent wave power fraction in aqueous environments (n = 1....

Romeo Bernini; Roberto Gravina; Genni Testa

2009-01-01

60

Single-frequency linear cavity erbium-doped fiber laser for fiber-optic sensing applications  

International Nuclear Information System (INIS)

We report a short-cavity fiber laser configured with a high-concentration erbium-doped fiber with stable single-frequency output. The fiber laser utilized a fiber Bragg grating inscribed into a piece of polarization-maintaining optical fiber as the output coupler to ensure a stable single frequency laser output. The polarization-maintaining optical fiber used in the output coupler is intended to provide the linearly polarized single-frequency laser output. The fiber laser had a maximum hundreds of micron-Watt level power output pumped by a fiber pigtailed laser diode working at 980 nm. Mode hopping phenomenon was eliminated in such a short-cavity fiber laser. Laser frequency stability less than 400 MHz over 10 minutes was obtained

61

An Implantable Neural Sensing Microsystem with Fiber-Optic Data Transmission and Power Delivery  

OpenAIRE

We have developed a prototype cortical neural sensing microsystem for brain implantable neuroengineering applications. Its key feature is that both the transmission of broadband, multichannel neural data and power required for the embedded microelectronics are provided by optical fiber access. The fiber-optic system is aimed at enabling neural recording from rodents and primates by converting cortical signals to a digital stream of infrared light pulses. In the full microsystem whose performa...

Yoon-Kyu Song; Nurmikko, Arto V.; Mingyu Kang; Sunmee Park; Borton, David A.

2013-01-01

62

A reflection-based localized surface plasmon resonance fiber-optic probe for biochemical sensing  

OpenAIRE

We report the fabrication and characterization of an optical fiber biochemical sensing probe based on localized surface plasmon resonance (LSPR) and spectra reflection. Ordered array of gold nanodots was fabricated on the optical fiber end facet using electron-beam lithography (EBL). We experimentally demonstrated for the first time the blue shift of the LSPR scattering spectrum with respected to the LSPR extinction spectrum, which had been predicted theoretically. High sensitivity [195.72 nm...

Lin, Yongbin; Zou, Yang; Lindquist, Robert G.

2011-01-01

63

Multifunctional sensing film used for fiber optic cholesterol sensor  

Science.gov (United States)

In this paper, by using ethyl silicate, ethanol and fluorescence indicator as the precursors, the multifunctional optic biosensing (MOBS) film containing cholesterol oxidase and the fluorescence indicator was prepared by sol-gel method. This biosensing film has both the function of biocatalyst and oxygen biosensing and can be used as the effective biosensing materials for fiber optic cholesterol sensor. The fiber optical cholesterol sensor based on fluorescence quenching was designed and fabricated using lock-in amplifying technology to realize the detection of cholesterol concentration. The experimental results showed that the best precursor proportion in volume ratio is: ethyl silicate: ethanol: 0.01 M HCl = 5: 8: 1.6. The drying rate of the sol could be controlled by using formamide as the controlling drier. When 16% of formamide were added in the mixing system, the cracks of the film could be reduced greatly and the immobilization of cholesterol oxidase and the fluorescence indicator could be improved effectively. A linear relationship between phase delay ? and the cholesterol concentration was observed in the range of 100 to 500 mg/dL. Since the cholesterol concentration is in the range of 140 to 200 mg/dL in the blood of healthy people, it will be possible for the sensor to be used in clinical detection. The biosensor with MOBS film has the response time of about 30 s, which is rather fast for a biosensor, and the relative deviation of +/-5.03%. This biosensor also has good stability.

Wang, Bin; Huang, Jun; Li, Mingtian; Zhou, Xuan

2008-12-01

64

E-Beam Patterned Gold Nanodot Arrays on Optical Fiber Tips for Localized Surface Plasmon Resonance Biochemical Sensing  

OpenAIRE

Electron beam lithography (EBL) was used to directly pattern periodic gold nanodot arrays on optical fiber tips. Localized surface plasmon resonance of the E-beam patterned gold nanodot arrays on optical fiber tips was utilized for biochemical sensing. The advantage of the optical fiber based localized surface plasmon resonance (LSPR) sensors is the convenience to work with and work in harsh environments. An optical fiber tip LSPR refractive index sensor of 196 nm per refractive index unit (R...

Yongbin Lin; Yang Zou; Yuanyao Mo; Junpeng Guo; Lindquist, Robert G.

2010-01-01

65

Current sensing in magnetic fusion experiments by faraday rotation in single-mode optical fibers  

International Nuclear Information System (INIS)

Interest in measurement devices which use optical fibers as the sensing element has increased rapidly in the last few years. Fibers interact with their environments in a number of useful ways. Most sensors developed so far have coupled the fiber mechanically to a transducer element which strains the fiber in response to an external field; the strain is measured interferometrically. Applications of this method include acoustic and field sensors. A second important class of sensors exploits the elasto-, electro-, and magnetooptic properties of the fiber material to directly sense the relevant fields. The sensors we report here are of this type. Essentially all of the sensor work uses single-mode fiber; in the beginning fiber intended for telecommunications applications was used but several companies now supply single-mode fiber optimized in various ways for sensors. Exploitation of the Faraday effect in glass fibers for the measurement of current was reported by Smith, Papp and Harms, and others. The authors became interested in using this technique on CTR magnetic fusion experiments because the unique dielectric properties of optical fibers hold promise for making possible the measurement of magnetic fields and currents where present techniques could not, and for avoiding some of the problems associated with the Rogowski coil-integrator system widely used now. Some experiments, the difficulties encountered, and the prospect for continued development of this diagnostic continued development of this diagnostic technique are reported

66

Use of nondestructive inspection and fiber optic sensing for damage characterization in carbon fiber fuselage structure  

Science.gov (United States)

To investigate a variety of nondestructive inspection technologies and assess impact damage characteristics in carbon fiber aircraft structure, the FAA Airworthiness Assurance Center, operated by Sandia National Labs, fabricated and impact tested two full-scale composite fuselage sections. The panels are representative of structure seen on advanced composite transport category aircraft and measured approximately 56"x76". The structural components consisted of a 16 ply skin, co-cured hat-section stringers, fastened shear ties and frames. The material used to fabricate the panels was T800 unidirectional pre-preg (BMS 8-276) and was processed in an autoclave. Simulated hail impact testing was conducted on the panels using a high velocity gas gun with 2.4" diameter ice balls in collaboration with the University of California San Diego (UCSD). Damage was mapped onto the surface of the panels using conventional, hand deployed ultrasonic inspection techniques, as well as more advanced ultrasonic and resonance scanning techniques. In addition to the simulated hail impact testing performed on the panels, 2" diameter steel tip impacts were used to produce representative impact damage which can occur during ground maintenance operations. The extent of impact damage ranges from less than 1 in2 to 55 in2 of interply delamination in the 16 ply skin. Substructure damage on the panels includes shear tie cracking and stringer flange disbonding. It was demonstrated that the fiber optic distributed strain sensing system is capable of detecting impact damage when bonded to the backside of the fuselage.

Neidigk, Stephen; Le, Jacqui; Roach, Dennis; Duvall, Randy; Rice, Tom

2014-04-01

67

Characterization of Flexible Copolymer Optical Fibers for Force Sensing Applications  

Directory of Open Access Journals (Sweden)

Full Text Available In this paper, different polymer optical fibres for applications in force sensing systems in textile fabrics are reported. The proposed method is based on the deflection of the light in fibre waveguides. Applying a force on the fibre changes the geometry and affects the wave guiding properties and hence induces light loss in the optical fibre. Fibres out of three different elastic and transparent copolymer materials were successfully produced and tested. Moreover, the influence of the diameter on the sensing properties was studied. The detectable force ranges from 0.05 N to 40 N (applied on 3 cm of fibre length, which can be regulated with the material and the diameter of the fibre. The detected signal loss varied from 0.6% to 78.3%. The fibres have attenuation parameters between 0.16–0.25 dB/cm at 652 nm. We show that the cross-sensitivies to temperature, strain and bends are low. Moreover, the high yield strength (0.0039–0.0054 GPa and flexibility make these fibres very attractive candidates for integration into textiles to form wearable sensors, medical textiles or even computing systems.

Lukas J. Scherer

2013-09-01

68

Remote Management for Multipoint Sensing Systems Using Hetero-Core Spliced Optical Fiber Sensors  

OpenAIRE

This paper describes the design and experimental verification of a multipoint sensing system with hetero-core spliced optical fiber sensors and its remote management using an internet-standard protocol. The study proposes two different types of design and conducts experiments to verify those systems’ feasibility. In order to manage the sensing systems remotely, the management method uses a standard operation and maintenance protocol for internet: the Simple Network Management Protocol is pr...

Lee See Goh; Yuji Anoda; Watanabe Kazuhiro; Norihiko Shinomiya

2013-01-01

69

Hierarchical fiber-optic-based sensing system: impact damage monitoring of large-scale CFRP structures  

International Nuclear Information System (INIS)

This study proposes a novel fiber-optic-based hierarchical sensing concept for monitoring randomly induced damage in large-scale composite structures. In a hierarchical system, several kinds of specialized devices are hierarchically combined to form a sensing network. Specifically, numerous three-dimensionally structured sensor devices are distributed throughout the whole structural area and connected with an optical fiber network through transducing mechanisms. The distributed devices detect damage, and the fiber-optic network gathers the damage signals and transmits the information to a measuring instrument. This study began by discussing the basic concept of a hierarchical sensing system through comparison with existing fiber-optic-based systems, and an impact damage detection system was then proposed to validate the new concept. The sensor devices were developed based on comparative vacuum monitoring (CVM), and Brillouin-based distributed strain measurement was utilized to identify damaged areas. Verification tests were conducted step-by-step, beginning with a basic test using a single sensor unit, and, finally, the proposed monitoring system was successfully verified using a carbon fiber reinforced plastic (CFRP) fuselage demonstrator. It was clearly confirmed that the hierarchical system has better repairability, higher robustness, and a wider monitorable area compared to existing systems

70

Advanced Fiber Optic-Based Sensing Technology for Unmanned Aircraft Systems  

Science.gov (United States)

This presentation provides an overview of fiber optic sensing technology development activities performed at NASA Dryden in support of Unmanned Aircraft Systems. Examples of current and previous work are presented in the following categories: algorithm development, system development, instrumentation installation, ground R&D, and flight testing. Examples of current research and development activities are provided.

Richards, Lance; Parker, Allen R.; Piazza, Anthony; Ko, William L.; Chan, Patrick; Bakalyar, John

2011-01-01

71

Fully-distributed fiber-optic high temperature sensing based on stimulated Brillouin scattering  

Science.gov (United States)

We proposed a Brillouin optical fiber time domain analysis (BOTDA)-based fully-distributed temperature system as high as 1000°C and spatial resolution to 5 meters. This technique is prominent for high spatial resolution fully distributed high temperature and stress sensing over long distance.

Wang, Jing; Hu, Di; Wang, Dorothy Y.; Wang, Anbo

2013-06-01

72

High sensitivity cascaded preamplifier with an optical bridge structure in Brillouin distributed fiber sensing system  

Science.gov (United States)

Fiber amplifiers such as Erbium-doped fiber amplifier (EDFA) played a key role in developing long-haul transmission system and have been an important element for enabling the development of optical communication system. EDFA amplifies the optical signal directly, without the optical-electric-optical switch and has the advantages such as high gain, broad band, low noise figure. It is widely used in repeaterless submarine system, smart grid and community antenna television system. This article describe the application of optical-fiber amplifiers in distributed optical fiber sensing system, focusing on erbium-doped fiber preamplifiers in modern transmission optical systems. To enhance the measurement range of a spontaneous Brillouin intensity based distributed fiber optical sensor and improve the receiver sensitivity, a two cascaded EDFAs C-band preamplifier with an optical bridge structure is proposed in this paper. The first cascaded EDFA is consisted of a length of 4.3m erbium-doped fiber and pumped in a forward pump light using a laser operating at 975nm. The second one made by using a length of 16m erbium-doped fiber is pumped in a forward pump light which is the remnant pump light of the first cascaded EDFA. At the preamplifier output, DWDM, centered at the signal wavelength, is used to suppress unwanted amplified spontaneous emission. The experimental results show that the two cascade preamplifier with a bridge structure can be used to amplify for input Brillouin backscattering light greater than about -43dBm. The optical gain is characterized and more than 26dB is obtained at 1549.50nm with 300mW pump power.

Bi, Weihong; Lin, Hang; Fu, Xinghu; Fu, Guangwei

2013-12-01

73

Research of AGC technology in a digital optical fiber sensing system with PGC modulation and demodulation  

Science.gov (United States)

The magnitude of light intensity on the photo-to-electric detector fluctuates all the time in an optic fiber sensing system, because of the influence of various factors in the fiber optic sensing system and from the external environment. As a result of the excessive intensity, the electric signal will be overload after the amplifier circuit with constant enlargement factor, and when the light intensity becames too small, it will reduce the signal-to-noise ratio of the electric signal. Therefore, it is necessary to introduce an automatic gain control (AGC) module into the system, which can insure the electric signal in a reasonable magnitude. In order to solve the problem of optic intensity fluctuating in the optical fiber sensing system with PGC modulation and demodulation, in this paper, firstly, it is analyzed that the impact of different magnitudes of interferential intensity to the PGC demodulation in theory. Secondly, a reasonable control method is put forward and an AGC module based on the AD602 chip is designed and produced. Finally, it is proved that the optic fiber sensor system with an AGC module has strong ability to resist fluctuation of light intensity within 40dB.

Tang, Jianfeng; Xiong, Shuidong; Zhang, Yan

2014-11-01

74

Shear stress sensing with Bragg grating-based sensors in microstructured optical fibers.  

Science.gov (United States)

We demonstrate shear stress sensing with a Bragg grating-based microstructured optical fiber sensor embedded in a single lap adhesive joint. We achieved an unprecedented shear stress sensitivity of 59.8 pm/MPa when the joint is loaded in tension. This corresponds to a shear strain sensitivity of 0.01 pm/µ?. We verified these results with 2D and 3D finite element modeling. A comparative FEM study with conventional highly birefringent side-hole and bow-tie fibers shows that our dedicated fiber design yields a fourfold sensitivity improvement. PMID:24105585

Sulejmani, Sanne; Sonnenfeld, Camille; Geernaert, Thomas; Luyckx, Geert; Van Hemelrijck, Danny; Mergo, Pawel; Urbanczyk, Waclaw; Chah, Karima; Caucheteur, Christophe; Mégret, Patrice; Thienpont, Hugo; Berghmans, Francis

2013-08-26

75

Fiber Optic Sensing Monitors Strain and Reduces Costs  

Science.gov (United States)

In applications where stress on a structure may vary widely and have an unknown impact on integrity, a common engineering strategy has been overbuilding to ensure a sufficiently robust design. While this may be appropriate in applications where weight concerns are not paramount, space applications demand a bare minimum of mass, given astronomical per-pound launch costs. For decades, the preferred solution was the tactic of disassembly and investigation between flights. Knowing there must be a better way, Dr. Mark Froggatt, of Langley Research Center, explored alternate means of monitoring stresses and damage to the space shuttle. While a tear-it-apart-and-have-a-look strategy was effective, it was also a costly and time consuming process that risked further stresses through the very act of disassembly and reassembly. An alternate way of monitoring the condition of parts under the enormous stresses of space flight was needed. Froggatt and his colleagues at Langley built an early-warning device to provide detailed information about even minuscule cracks and deformations by etching a group of tiny lines, or grating, on a fiber optic cable five-thousandths of an inch thick with ultraviolet light. By then gluing the fiber to the side of a part, such as a fuel tank, and shining a laser beam down its length, reflected light indicated which gratings were under stress. Inferring this data from measurements in light rather than in bonded gauges saved additional weight. Various shuttle components now employ the ultrasonic dynamic vector stress sensor (UDVSS), allowing stress detection by measuring light beamed from a built-in mini-laser. By measuring changes in dynamic directional stress occurring in a material or structure, and including phase-locked loop, synchronous amplifier, and contact probe, the UDVSS proved especially useful among manufacturers of aerospace and automotive structures for stress testing and design evaluation. Engineers could ensure safety in airplanes and spaceships with a narrower, not overbuilt, margin of safety. For this development, in 1997, Discover Magazine named Froggatt a winner in the "Eighth Annual Awards for Technological Innovation" from more than 4,000 entries.

2008-01-01

76

Semiconductor Optical Amplifier (SOA-Fiber Ring Laser and Its Application to Stress Sensing  

Directory of Open Access Journals (Sweden)

Full Text Available We have developed a novel optical fiber ring laser using a semiconductor optical amplifier (SOA as the gain medium, and taking advantage of polarization anisotropy of its gain. The frequency difference of the bi-directional laser is controlled by birefringence which is introduced in the ring laser cavity. The beat frequency generated by combining two counter-propagating oscillations is proportional to the birefringence, the fiber ring laser of the present study is, therefore, applicable to the fiber sensor. The sensing signal is obtained in a frequency domain with the material which causes the retardation change by a physical phenomenon to be measured. For the application to stress sensing, the present laser was investigated with a photoelastic material.

Yoshitaka Takahashi

2011-12-01

77

Performance of digital incoherent OFDR and prospects for optical fiber sensing applications  

Science.gov (United States)

We propose a digital implementation of the incoherent optical frequency domain reflectometry (I-OFDR) technique for precise backscatter measurement and optical fiber sensing applications. Specific performance parameters of the I-OFDR are discussed and compared to an analog vector network analyzer-based I-OFDR system. Improved sensitivity, dynamic range and signal stability of the digital I-OFDR is presented and demonstrated by means of quasi-distributed length change measurement.

Liehr, Sascha; Nöther, Nils; Steffen, Milan; Gili, Oriol; Krebber, Katerina

2014-05-01

78

Design and Fabrication of Fiber-Optic Nanoprobes for Optical Sensing  

OpenAIRE

Abstract This paper describes the design and fabrication of fiber-optic nanoprobes developed for optical detection in single living cells. It is critical to fabricate probes with well-controlled nanoapertures for optimized spatial resolution and optical transmission. The detection sensitivity of fiber-optic nanoprobe depends mainly on the extremely small excitation volume that is determined by the aperture sizes and penetration depths. We investigate the angle dependence of the aperture in sh...

Zhang Yan; Dhawan Anuj; Vo-Dinh Tuan

2010-01-01

79

Sensing characteristics of clad-modified with nanocrystalline metal oxide fiber optic gas sensor  

Science.gov (United States)

Clad-modified with nanocrystalline metal oxide fiber optic gas sensors have been proposed for ambient temperature operation. The sensor output light intensity either increases or decreases when the gas concentration is increased. Study shows that optical properties of metal-oxides with air medium influence the gas sensing. Absorption characteristics of nanocrystalline metal oxides ( ZnO, Sm2O3 and Ce doped ZnO etc., ) in air, methanol, ethanol and ammonia are analyzed as well as their effect on gas sensing.

Sastikumar, D.; Renganathan, B.

2014-11-01

80

Fiber Loop Ringdown — a Time-Domain Sensing Technique for Multi-Function Fiber Optic Sensor Platforms: Current Status and Design Perspectives  

OpenAIRE

Fiber loop ringdown (FLRD) utilizes an inexpensive telecommunications light source, a photodiode, and a section of single-mode fiber to form a uniform fiber optic sensor platform for sensing various quantities, such as pressure, temperature, strain, refractive index, chemical species, biological cells, and small volume of fluids. In FLRD, optical losses of a light pulse in a fiber loop induced by changes in a quantity are measured by the light decay time constants. FLRD measures time to detec...

Chuji Wang

2009-01-01

81

Characterization of time-resolved fluorescence response measurements for distributed optical-fiber sensing.  

Science.gov (United States)

A distributed optical-fiber sensing system based on pulsed excitation and time-gated photon counting has been used to locate a fluorescent region along the fiber. The complex Alq3 and the infrared dye IR-125 were examined with 405 and 780 nm excitation, respectively. A model to characterize the response of the distributed fluorescence sensor to a Gaussian input pulse was developed and tested. Analysis of the Alq3 fluorescent response confirmed the validity of the model and enabled the fluorescence lifetime to be determined. The intrinsic lifetime obtained (18.2±0.9 ns) is in good agreement with published data. The decay rate was found to be proportional to concentration, which is indicative of collisional deactivation. The model allows the spatial resolution of a distributed sensing system to be improved for fluorophores with lifetimes that are longer than the resolution of the sensing system. PMID:21102661

Sinchenko, Elena; Gibbs, W E Keith; Davis, Claire E; Stoddart, Paul R

2010-11-20

82

OptaSense distributed acoustic and seismic sensing using COTS fiber optic cables for infrastructure protection and counter terrorism  

Science.gov (United States)

The OptaSense® Distributed Acoustic Sensing (DAS) technology can turn any cable with single-mode optical fiber into a very large and densely sampled acoustic/seismic sensor array—covering up to a 50 km aperture per system with "virtual" sensor separations as small as 1 meter on the unmodified cable. The system uses Rayleigh scattering from the imperfections in the fiber to return the optical signals measuring local fiber strain from seismic or air and water acoustic signals. The scalable system architecture can provide border monitoring and high-security perimeter and linear asset protection for a variety of industries—from nuclear facilities to oil and gas pipelines. This paper presents various application architectures and system performance examples for detection, localization, and classification of personnel footsteps, vehicles, digging and tunneling, gunshots, aircraft, and earthquakes. The DAS technology can provide a costeffective alternative to unattended ground sensors and geophone arrays, and a complement or alternative to imaging and radar sensors in many applications. The transduction, signal processing, and operator control and display technology will be described, and performance examples will be given from research and development testing and from operational systems on pipelines, critical infrastructure perimeters, railroads, and roadways. Potential new applications will be discussed that can take advantage of existing fiber-optic telecommunications infrastructure as "the sensor"—leading to low-cost and high-coverage systems.

Duckworth, Gregory L.; Ku, Emery M.

2013-06-01

83

Double-ended calibration of fiber-optic Raman spectra distributed temperature sensing data:  

OpenAIRE

Over the past five years, Distributed Temperature Sensing (DTS) along fiber optic cables using Raman backscattering has become an important tool in the environmental sciences. Many environmental applications of DTS demand very accurate temperature measurements, with typical RMSE < 0.1 K. The aim of this paper is to describe and clarify the advantages and disadvantages of double-ended calibration to achieve such accuracy under field conditions. By measuring back...

John Selker; Hausner, Mark B.; Scott Tyler; Jop Jansen; Olivier Hoes; Steele-dunne, Susan C.; Nick van de Giesen

2012-01-01

84

High spatial resolution distributed sensing in optical fibers by Brillouin gain-profile tracing  

OpenAIRE

A novel BOTDA technique for distributed sensing of the Brillouin frequency in optical fibers with cm-order spatial resolution is proposed. The technique is based upon a simple modulation scheme, requiring only a single long pump pulse for acoustic excitation, and no subsequent interrogating pulse. Instead, the desired spatial mapping of the Brillouin response is extracted by taking the derivative of the probe signal. As a result, the spatial resolution is limited by the fall-time of the pump ...

Sperber, Tom; Eyal, Avishay; Tur, Moshe; The?venaz, Luc

2010-01-01

85

Distributed fiber-optic temperature sensing: recent improvements and Nagra's applications in the Mont Terri URL  

International Nuclear Information System (INIS)

Document available in extended abstract form only. Full text of publication follows: The application of fiber-optic sensors in large experiments in underground rock laboratories (URL) and for monitoring of pilot repositories offers several advantages in contrast to conventional sensors. By means of optical fibers distributed temperature and deformation measurements can be performed without electric or mechanical components at the measurement location reducing the risk of corrosion and sensor failure. As fiber-optic strain sensors are to some extend still in a prototype stage, we focus here on Raman spectra distributed fiber-optic temperature sensing (DTS). In DTS a fiber-optic cable, which is the temperature sensor, is connected to a light reading unit that sends laser-pulses into the fiber. The backscattered light is detected with high temporal resolution. From the two-way-light-travel-time the location of backscattering is determined. For the temperature information the amplitude ratio of the Stokes and anti-Stokes signals is analyzed. The Stokes and anti- Stokes signals are the result of the Raman effect. The ratio of these signals provides a quantity that depends only on the temperature of the fiber at the location of backscatter. With commercial DTS setups it is possible to measure the temperature distribution along several kilometer long cables with a temperature resolution of 0.01 C and a spatial resolution of 1 m. Recent developments in DTS focus on better temnt developments in DTS focus on better temperature precision and resolution. This advancement can be achieved by experiment-specific calibration techniques and sensor-layout as well as improved instruments. To realize high spatial resolution (cm range) wrapped fiber-optic cables can be applied. Another promising approach to monitor moisture along a fiber-optic cable installed in unconsolidated material are heatable cables. We will present a selection of the most recent advancements which may improve temperature monitoring in natural and engineered clay-barriers using DTS. In addition, first results and experiences of Nagra's DTS applications in the Mont Terri URL will be presented. Fiber-optic sensors were installed within the Full-Scale Emplacement (FE) Experiment. The FE-experiment is a full-scale heater test also simulating the construction, emplacement and backfilling of a repository tunnel according to the Swiss concept for high level waste. The THM evolution in the host rock (near- and far-field), tunnel lining and the engineered barrier system will be monitored by several hundred conventional sensors. In addition to thermo-resistive conventional temperature sensors fiber-optic cables amend the temperature monitoring. In the host rock 45 m long inclinometer casings are equipped with fiber-optic cables to observe the longitudinal temperature evolution above the tunnel. The temperature distribution at the interface engineered barrier - tunnel lining is planned to be monitored by fiber-optic cables covering the surface of the tunnel lining. The fiber-optics in combination with the conventional temperature sensors will result in detailed insights into non-uniformity of heat transport within the engineered barrier and the host rock caused by spatial and temporal variability of thermal conductivity and therewith saturation and porosity. (authors)

86

Optical fiber with nanostructured cladding of TiO2 nanoparticles self-assembled onto a side polished fiber and its temperature sensing.  

Science.gov (United States)

We demonstrated temperature sensing of a fiber with nanostructured cladding, which was constructed by titanium dioxide TiO2 nanoparticles self-assembled onto a side polished optical fiber (SPF). Significantly enhanced interaction between the propagating light and the TiO2 nanoparticles (TN) can be obtained via strong evanescent field of the SPF. The strong light-TN interaction results in temperature sensing with a maximum optical power variation of ~4dB in SPF experimentally for an external environment temperature varying from -7.8°C to 77.6°C. The novel temperature sensing device shows a linear correlation coefficient of better than 99.4%, and a sensitivity of ~0.044 dB/°C. The TN-based all-fiber-optic temperature sensing characteristics was successfully demonstrated, and it is compatible with fiber-optic interconnections and high potential in photonics applications. PMID:25607212

Lu, Huihui; Tian, Zhengwen; Yu, Haiping; Yang, Bing; Jing, Guangyin; Liao, Guozhen; Zhang, Jun; Yu, Jianhui; Tang, Jieyuan; Luo, Yunhan; Chen, Zhe

2014-12-29

87

Fiber Optic Sensors for Health Monitoring of Morphing Airframes. Part 2; Chemical Sensing Using Optical Fibers with Bragg Gratings  

Science.gov (United States)

Part 1 of this two part series described the fabrication and calibration of Bragg gratings written into a single mode optical fiber for use in strain and temperature monitoring. Part 2 of the series describes the use of identical fibers and additional multimode fibers, both with and without Bragg gratings, to perform near infrared spectroscopy. The demodulation system being developed at NASA Langley Research Center currently requires the use of a single mode optical fiber. Attempts to use this single mode fiber for spectroscopic analysis are problematic given its small core diameter, resulting in low signal intensity. Nonetheless, we have conducted a preliminary investigation using a single mode fiber in conjunction with an infrared spectrometer to obtain spectra of a high-performance epoxy resin system. Spectra were obtained using single mode fibers that contained Bragg gratings; however, the peaks of interest were barely discernible above the noise. The goal of this research is to provide a multipurpose sensor in a single optical fiber capable of measuring a variety of chemical and physical properties.

Wood, Karen; Brown, Timothy; Rogowski, Robert; Jensen, Brian

2000-01-01

88

Spectroscopic and fiber optic ethanol sensing properties Gd doped ZnO nanoparticles.  

Science.gov (United States)

We report the structural, optical and gas sensing properties of prepared pure and Gd doped ZnO nanoparticles through solgel method at moderate temperature. Structural studies are carried out by X-ray diffraction method confirms hexagonal wurtzite structure and doping induced changes in lattice parameters is observed. Optical absorption spectral studies shows red shift in the absorption peak corresponds to band-gap from 3.42 eV to 3.05 eV and broad absorption in the visible range after Gd doping is observed. Scanning electron microscopic studies shows increase in particle size where the particle diameters increase from few nm to micrometers after Gd doping. The clad modified ethanol fiber-optic sensor studies for ethanol sensing exhibits best sensitivity for the 3% Gd doped ZnO nanoparticles and the sensitivity get lowered incase of higher percentage of Gd doped ZnO sample. PMID:24892544

Noel, J L; Udayabhaskar, R; Renganathan, B; Muthu Mariappan, S; Sastikumar, D; Karthikeyan, B

2014-11-11

89

Spectroscopic and fiber optic ethanol sensing properties Gd doped ZnO nanoparticles  

Science.gov (United States)

We report the structural, optical and gas sensing properties of prepared pure and Gd doped ZnO nanoparticles through solgel method at moderate temperature. Structural studies are carried out by X-ray diffraction method confirms hexagonal wurtzite structure and doping induced changes in lattice parameters is observed. Optical absorption spectral studies shows red shift in the absorption peak corresponds to band-gap from 3.42 eV to 3.05 eV and broad absorption in the visible range after Gd doping is observed. Scanning electron microscopic studies shows increase in particle size where the particle diameters increase from few nm to micrometers after Gd doping. The clad modified ethanol fiber-optic sensor studies for ethanol sensing exhibits best sensitivity for the 3% Gd doped ZnO nanoparticles and the sensitivity get lowered incase of higher percentage of Gd doped ZnO sample.

Noel, J. L.; Udayabhaskar, R.; Renganathan, B.; Muthu Mariappan, S.; Sastikumar, D.; Karthikeyan, B.

2014-11-01

90

E-Beam Patterned Gold Nanodot Arrays on Optical Fiber Tips for Localized Surface Plasmon Resonance Biochemical Sensing  

Directory of Open Access Journals (Sweden)

Full Text Available Electron beam lithography (EBL was used to directly pattern periodic gold nanodot arrays on optical fiber tips. Localized surface plasmon resonance of the E-beam patterned gold nanodot arrays on optical fiber tips was utilized for biochemical sensing. The advantage of the optical fiber based localized surface plasmon resonance (LSPR sensors is the convenience to work with and work in harsh environments. An optical fiber tip LSPR refractive index sensor of 196 nm per refractive index unit (RIU sensitivity has been demonstrated. The affinity sensing property of the fiber tip sensor was demonstrated using biotin/streptavidin as the receptor/analyte. The detection limit for streptavidin was determined to be 6 pM.

Yongbin Lin

2010-10-01

91

Early work on fiber optic gyro technology at McDonnell Douglas and spinoffs leading to acoustic sensing, distributed sensing, and a secure fiber optic communication system  

Science.gov (United States)

In the late 1970s the closed loop fiber optic gyro was invented and demonstrated at McDonnell Douglas Astronautics Company in Huntington Beach, California. This development was followed by a series of derivative inventions that included the Sagnac acoustic sensor, Sagnac distributed sensors and finally a Sagnac secure fiber optic communication system. This paper provides an overview of these developments.

Udd, Eric

2006-08-01

92

FIBER OPTICAL MICRO-DETECTORS FOR OXYGEN SENSING IN POWER PLANTS  

Energy Technology Data Exchange (ETDEWEB)

A reflection mode fiber optic oxygen sensor is being developed that can operate at high temperatures for power plant applications. The sensor is based on the {sup 3}O{sub 2} quenching of the red emission from hexanuclear molybdenum chloride clusters. Two critical materials issues are the cluster's ability to withstand high temperatures when immobilized in a porous the sol-gel support, and whether after heating to high temperatures, the sol-gel matrix maintains a high and constant permeability to oxygen to support rapid quenching of luminescence. We used a composite materials approach to prepare stable sensing layers on optical fibers. We dispersed 60 w/w% of a pre-cured sol-gel composite containing the potassium salt of molybdenum clusters (K{sub 2}Mo{sub 6}Cl{sub 14}) into a sol-gel binder solution, and established the conditions necessary for deposition of sol-gel films on optical fibers and planar substrates. The fiber sensor has an output signal of 5 nW when pumped with an inexpensive commercial 365 nm ultraviolet light emitting diode (LED). Quenching of the sensor signal by oxygen was observed up to a gas temperature of 175 C with no degradation of the oxygen permeability of the composite after high temperature cycling. On planar substrates the cluster containing composite responds within <1 second to a gas exchange from nitrogen to oxygen, indicating the feasibility of real-time oxygen detection.

Gregory L. Baker; Ruby N. Ghosh; D.J. Osborn III; Po Zhang

2005-07-01

93

Simultaneous strain and temperature sensing using a slightly tapered optical fiber with an inner cavity.  

Science.gov (United States)

An ultracompact optical fiber mode interferometer capable of performing simultaneous strain and temperature sensing is demonstrated. The device is fabricated by using femtosecond laser micromachining together with fusion splicing techniques and followed by a tapering process. The transmission spectrum of the device exhibits a number of resonance wavelength dips, corresponding to different orders of cladding mode, which allow simultaneous strain and temperature sensing by monitoring the variation of selected two wavelength dips. The sensitivity achieved is -16.12 pm ??(-1) and 85.95 pm °C(-1) for strain and temperature, respectively. The device has a spatially precise sensing capability owing to the small size of the inner air-cavity. PMID:25631366

Chen, H F; Wang, D N; Wang, Y

2015-03-01

94

Long term structural health monitoring by distributed fiber-optic sensing  

Science.gov (United States)

Structural health monitoring (SHM) systems allow to detect unusual structural behaviors that indicate a malfunction in the structure, which is an unhealthy structural condition. Depending on the complexity level of the SHM system, it can even perform the diagnosis and the prognosis steps, supplying the required information to carry out the most suitable actuation. While standard SHM systems are based on the use of point sensors (e.g., strain gauges, crackmeters, tiltmeters, etc.), there is an increasing interest towards the use of distributed optical fiber sensors, in which the whole structure is monitored by use of a single optical fiber. In particular, distributed optical fiber sensors based on stimulated Brillouin scattering (SBS) permit to detect the strain in a fully distributed manner, with a spatial resolution in the meter or submeter range, and a sensing length that can reach tens of km. These features, which have no performance equivalent among the traditional electronic sensors, are to be considered extremely valuable. When the sensors are opportunely installed on the most significant structural members, this system can lead to the comprehension of the real static behaviour of the structure rather than merely measuring the punctual strain level on one of its members. In addition, the sensor required by Brillouin technology is an inexpensive, telecom-grade optical fiber that shares most of the typical advantages of other fiber-optic sensors, such as high resistance to moisture and corrosion, immunity to electromagnetic fields and potential for long-term monitoring. In this work, we report the result of a test campaign performed on a concrete bridge. In particular, the tests were performed by an portable prototype based on Brillouin Optical Time-Domain Analysis (BOTDA) [1,2]. This type of analysis makes use of a pulsed laser light and a frequency-shifted continuous-wave (CW) laser light, launched simultaneously at the two opposite ends of an optical fiber acting as the sensing element. By measuring the intensity of the transmitted CW light at various frequency shifts, the Brillouin frequency shift profile along the fiber is retrieved. As the Brillouin frequency shift is linearly dependent on strain (with a coefficient of about 500 MHz/%) and temperature (with a coefficient of about 1 MHz/°C), the instrument provides a measure of strain or temperature at each location along the fiber, with a spatial resolution determined by the duration of the optical pulse (we set a 1m-resolution in our tests). It is important to note that only a few examples of in-field demonstration of bridge monitoring by distributed sensors have been reported. The optical fiber sensor was attached along one arch of the bridge using two types of adhesive for comparison purposes. The attached fiber was able to provide the strain distribution along the structure during the one-year test campaign and with a spatial resolution of one meter. A crack was revealed and correctly localized by the distributed sensor. Acknowledgements The authors thank F.Soldovieri, M. Bavusi and A. Loperte for the with measurements. The research leading to these results has received funding from the European Community's Seventh Framework Programme (FP7/2007-2013) under Grant Agreement n° 225663.

Persichetti, G.; Minardo, A.; Testa, G.; Bernini, R.

2012-04-01

95

Optical characteristics of coated long-period fiber grating and their sensing application  

Science.gov (United States)

Based on rigorous coupled mode theory, a theoretical model is established for studying the optical characteristics of long-period fiber grating (LPFG) coated with the sensing thin films. The vector components of the electric field and the local intensity curves for the lowest order cladding mode are plotted to study the field distribution of cladding mode. It is found that the transverse field components of HE 11 cladding mode are approximately 102 times larger about than the longitudinal field components, and the low order HE modes have a larger proportion of intensity localized in the core than the low order EH modes, just like the double-clad LPFG. Further, the influences of the sensing film optical parameters and grating structure parameters on the attenuation peak of transmission spectra are analyzed. Data simulation shows that the sensitivity to the refractive index of sensing films is predicted to be more than 10 -7. The optimal design parameters of the LPFG film sensor for higher sensitivity are ascertained by plotting the contour of the sensor sensitivity. Experimentally, the sol-gel derived SnO II film LPFG was prepared, and a preliminary gas-sensing test for detection of C IIH 5OH was performed. The results indicate that the LPFG film sensor with structure optimization has higher sensitivity, and the detection sensitivity is available to 10 -1ppm on the condition of optimum optical parameters. With the advantages of both film sensors and fiber sensors, the coated LPFG sensor has a wide and promising application prospect in process analytical chemistry, environmental monitoring, and biochemical sensing.

Gu, Zhengtian; Xu, Yanping; Deng, Chuanlu

2007-12-01

96

An Implantable Neural Sensing Microsystem with Fiber-Optic Data Transmission and Power Delivery  

Directory of Open Access Journals (Sweden)

Full Text Available We have developed a prototype cortical neural sensing microsystem for brain implantable neuroengineering applications. Its key feature is that both the transmission of broadband, multichannel neural data and power required for the embedded microelectronics are provided by optical fiber access. The fiber-optic system is aimed at enabling neural recording from rodents and primates by converting cortical signals to a digital stream of infrared light pulses. In the full microsystem whose performance is summarized in this paper, an analog-to-digital converter and a low power digital controller IC have been integrated with a low threshold, semiconductor laser to extract the digitized neural signals optically from the implantable unit. The microsystem also acquires electrical power and synchronization clocks via optical fibers from an external laser by using a highly efficient photovoltaic cell on board. The implantable unit employs a flexible polymer substrate to integrate analog and digital microelectronics and on-chip optoelectronic components, while adapting to the anatomical and physiological constraints of the environment. A low power analog CMOS chip, which includes preamplifier and multiplexing circuitry, is directly flip-chip bonded to the microelectrode array to form the cortical neurosensor device.

Yoon-Kyu Song

2013-05-01

97

An Implantable Neural Sensing Microsystem with Fiber-Optic Data Transmission and Power Delivery  

Science.gov (United States)

We have developed a prototype cortical neural sensing microsystem for brain implantable neuroengineering applications. Its key feature is that both the transmission of broadband, multichannel neural data and power required for the embedded microelectronics are provided by optical fiber access. The fiber-optic system is aimed at enabling neural recording from rodents and primates by converting cortical signals to a digital stream of infrared light pulses. In the full microsystem whose performance is summarized in this paper, an analog-to-digital converter and a low power digital controller IC have been integrated with a low threshold, semiconductor laser to extract the digitized neural signals optically from the implantable unit. The microsystem also acquires electrical power and synchronization clocks via optical fibers from an external laser by using a highly efficient photovoltaic cell on board. The implantable unit employs a flexible polymer substrate to integrate analog and digital microelectronics and on-chip optoelectronic components, while adapting to the anatomical and physiological constraints of the environment. A low power analog CMOS chip, which includes preamplifier and multiplexing circuitry, is directly flip-chip bonded to the microelectrode array to form the cortical neurosensor device. PMID:23666130

Park, Sunmee; Borton, David A.; Kang, Mingyu; Nurmikko, Arto V.; Song, Yoon-Kyu

2013-01-01

98

Integrated guided wave generation and sensing using a single laser source and optical fibers  

International Nuclear Information System (INIS)

This study proposes an integrated lead zirconate titanate/fiber Bragg grating (PZT/FBG) system that can generate and measure guided waves for structural health monitoring (SHM) using a common laser source and optical cables. Among various SHM devices used for guided wave generation and sensing, PZT transducers and FBG sensors have been widely used because of their light weight, non-intrusive nature and compactness. To take the best advantage of the merits of these SHM devices, a combination of PZT-based guided wave generation and FBG-based sensing has been attempted by some researchers. However, the existing hybrid approaches have two independent systems: a wave generation system using electrical devices and a sensing system with optical devices. We have developed a fully integrated PZT/FBG system that uses a single laser source and optical cables. This system can alleviate problems associated with conventional electrical cables, such as electromagnetic interference, signal attenuation and vulnerability to noise. A tunable laser, the common power source for guided wave generation and sensing, is modulated and amplified to excite PZT. This laser is also used with FBG sensors for measuring high-speed strain changes induced by guided waves. The feasibility of this system has been experimentally demonstrated using an aluminum plate

99

Fiber optic detector  

Energy Technology Data Exchange (ETDEWEB)

This invention is comprised of a portable fiber optic detector that senses the presence of specific target chemicals by exchanging the target chemical for a fluorescently-tagged antigen that is bound to an antibody which is in turn attached to an optical fiber. Replacing the fluorescently-tagged antigen reduces the fluorescence so that a photon sensing detector records the reduced light level and activates an appropriate alarm or indicator.

Partin, J.K.; Ward, T.E.; Grey, A.E.

1990-12-31

100

Ammonia sensing properties of tapered plastic optical fiber coated with silver nanoparticles/PVP/PVA hybrid  

Science.gov (United States)

A tapered plastic optical fiber gas sensor coated with silver nanoparticles/PVP/PVA hybrid is proposed for ammonia gas sensing application. The spectral characteristics of the gas sensor for different silver concentrations were studied at room temperature against various concentrations (0-500 ppm) of ammonia, methanol and ethanol. All the samples exhibited a linear decrease in spectral intensity with the increase in concentration of ammonia whereas it showed little effect for methanol and ethanol. Gas sensitivity studies revealed that the sensors exhibit higher sensitivity at higher concentrations of silver nanoparticles than at lower concentrations. The spectral characteristics of the sensor selectively represented its ammonia sensitivity.

Rithesh Raj, D.; Prasanth, S.; Vineeshkumar, T. V.; Sudarsanakumar, C.

2015-04-01

101

Long Period Gratings in Random Hole Optical Fibers for Refractive Index Sensing  

Directory of Open Access Journals (Sweden)

Full Text Available We have demonstrated the fabrication of long period gratings in random hole optical fibers. The long period gratings are fabricated by a point-by-point technique using a CO2 laser. The gratings with a periodicity of 450 µm are fabricated and a maximum coupling efficiency of ?9.81 dB has been achieved. Sensing of different refractive indices in the surrounding mediums is demonstrated by applying standard liquids with refractive indices from 1.400 to 1.440 to the long period grating.

Gary Pickrell

2011-01-01

102

Optic fiber sensor-based smart bridge cable with functionality of self-sensing  

Science.gov (United States)

Bridge cables, characterized by distributed large span, serving in harsh environment and vulnerability to random damage, are the key load-sustaining components of cable-based bridges. To ensure the safety of the bridge structure, it is critical to monitor the loading conditions of these cables under lengthwise random damages. Aiming at obtaining accurate monitoring at the critical points as well as the general information of the cable force distributed along the entire cable, this paper presents a study on cable force monitoring by combining optical fiber Bragg grating (FBG) sensors and Brillouin optical time domain analysis/reflectory (BOTDA/R) sensing technique in one single optical fiber. A smart FRP-OF-FBG rebar based cable was fabricated by protruding a FRP packaged OF-FBG sensor into the bridge cable. And its sensing characteristics, stability under high stress state temperature self-compensation as well as BOTDA/R distributed data improvement by local FBG sensors have been investigated. The results show that FRP-OF-FBG rebar in the smart cable can deform consistantly along with the steel wire and the cable force obtained from the optical fiber sensors agree well with theoretical value with relative error less than ±5%. Besides, the temperature self-compensation method provides a significant cost-effective technique for the FRP-OF-FBG based cables' in situ cable force measurement. And furthermore, potential damages of the bridge cable, e.g. wire breaking and corrosion, can be characterized and symbolized by the discontinuity and fluctuation of the distributed BOTDA data thereafter accuracy improved by local FBG sensors.

He, Jianping; Zhou, Zhi; Jinping, Ou

2013-02-01

103

Optical Fiber Networks for Remote Fiber Optic Sensors  

OpenAIRE

This paper presents an overview of optical fiber sensor networks for remote sensing. Firstly, the state of the art of remote fiber sensor systems has been considered. We have summarized the great evolution of these systems in recent years; this progress confirms that fiber-optic remote sensing is a promising technology with a wide field of practical applications. Afterwards, the most representative remote fiber-optic sensor systems are briefly explained, discussing their schemes, challenges, ...

Montserrat Fernandez-Vallejo; Manuel Lopez-Amo

2012-01-01

104

High spatial resolution distributed sensing in optical fibers by Brillouin gain-profile tracing.  

Science.gov (United States)

A novel BOTDA technique for distributed sensing of the Brillouin frequency in optical fibers with cm-order spatial resolution is proposed. The technique is based upon a simple modulation scheme, requiring only a single long pump pulse for acoustic excitation, and no subsequent interrogating pulse. Instead, the desired spatial mapping of the Brillouin response is extracted by taking the derivative of the probe signal. As a result, the spatial resolution is limited by the fall-time of the pump modulation, and the phenomena of secondary "echo" signals, typically appearing in BOTDA sensing methods based upon pre-excitation, is mitigated. Experimental demonstration of the detection of a Brillouin frequency variation significantly smaller than the natural Brillouin linewidth, with a 2cm spatial resolution, is presented. PMID:20588710

Sperber, Tom; Eyal, Avishay; Tur, Moshe; Thévenaz, Luc

2010-04-12

105

Advantage of multi-mode sapphire optical fiber for evanescent-field SERS sensing.  

Science.gov (United States)

An unclad, multi-mode single crystal sapphire fiber was used as a platform, and immobilized colloidal Ag nanoparticles (NPs) were used as enabler, for evanescent-field fiber-optic sensing via surface-enhanced Raman scattering (SERS) of Rhodamine 6G (R6G) solution. The dependence of the measured Raman intensity on NP coverage density (to a maximum of 120??particles/?m²) as well as the coverage length (to a maximum of 6 cm) was investigated. We demonstrate the utility of SERS-active sapphire fibers for sensitive measurements (10?? M R6G). We further reveal, with the aid of theoretical analysis, that multi-mode fiber offers a significant advantage compared to its single-mode counterpart because the former allows two orders of magnitude higher particle coverage density than the latter to maximize SERS benefit, while maintaining the dominance of Raman gain despite the competitive interplay of NP-induced absorption and scattering loss along the interaction path length. PMID:25361094

Chen, Hui; Tian, Fei; Chi, Jingmao; Kanka, Jiri; Du, Henry

2014-10-15

106

Etched fiber optic sensing network in smart composite structures and its signal processing technology  

Science.gov (United States)

A three dimension sensing network, which is composed of periodically etched multi-mode optical fibers, is embedded in the laminated composite material structure of vertical tail-wing of plane for nondestructive evaluation of structural states in smart composite material and structures. The composite specimens in which sensing network is embedded are tested with stretching, bending and impacting. It is exhibited in the experiment that the responses of fiberoptic sensor are linear, repeatable, have a high sensitivity and no measurable hysteresis. The experimental results have shown the feasibility of embedded fiberoptic sensor network to be used to measure the structural states such as strain, stress and damage. The signal processing for the parallel and distributing fiberoptic sensing network by using artificial neural network is also described. In this paper, the BP network which is suitable for distributing sensing signal processing is studied, and the simulation has demonstrated that the BP network's ability for identifying the position of stress, strain and damage is above 90%.

Huang, Dexiu; Yang, Jiangliang

2001-02-01

107

Continuous monitoring of plant growth using fiber-optic interferrometric sensing  

Science.gov (United States)

Dendrometers, dendrographs and dry weight measurements have been successfully used for measurements of plant growth. These sensors have been used with Linear Variable Differential Transformer (LVDT) based data logging systems for continuous monitoring. In this paper the preliminary results for a prototype technique is presented as a proof of concept for the continuous monitoring of plant growth using an approach based on fiber-optic interferrometric sensing. The advantage of this sensing technique over the others is the ability to measure and analyze with very high sensitivities such as micron changes in dimensions allowing measurements over short time spans. The sensor was mounted on a Dracaena Sanderiana (Lucky Bamboo) shoot and the change in shoot length dimensions resulted in changes in the output signal display which is in the form of interferrometric fringes. The data acquisition is performed over a long duration using labVIEW based data logging. Filtered output of the data has been presented where an attempt has been made to relate the fringes to length changes. The sensing system is nondestructive and noninvasive and has been targeted to respond to changes in stem length due to changes in plant growth parameters. The objective is to provide a measurement system to do research in optimizing plant growth in greatly reduced time spans. This form of sensing application is also applicable for monitoring the growth of plants growing at much slower rates.

Chatterjee, Julius; Grossman, Barry G.

2011-06-01

108

Fiber-Optic Sensor with Simultaneous Temperature, Pressure, and Chemical Sensing Capabilities  

Energy Technology Data Exchange (ETDEWEB)

This project aimed to develop a multifunctional sensor suitable for process control application in chemical and petrochemical industries. Specifically, the objective was to demonstrate a fiber optic sensing system capable of simultaneous temperature, pressure, and chemical composition determinations based on a single strand of sapphire optical fiber. These capabilities were to be achieved through the incorporation of a phosphor and a Bragg grating into the fiber, as well as the exploitation of the evanescent field interaction of the optical radiation inside the fiber with the surrounding chemical medium. The integration of the three functions into a single probe, compared to having three separate probes, would not only substantially reduce the cost of the combined system, but would also minimize the intrusion into the reactor. Such a device can potentially increase the energy efficiency in the manufacture of chemical and petrochemical products, as well as reduce waste and lead to improved quality. In accordance with the proposed research plan, the individual temperature, pressure and chemical sensors where fabricated and characterized first. Then towards the end of the program, an integrated system was implemented. The sapphire fibers were grown on a laser heated pedestal growth system. The temperature sensor was based on the fluorescence decay principle, which exploits the temperature dependence of the fluorescence decay rate of the selected phosphor. For this project, Cr3+ was chosen as the phosphor, and it was incorporated into the sapphire fiber by coating a short length of the source rod with a thin layer of Cr2O3. After the viability of the technique was established and the growth parameters optimized, the temperature sensor was characterized up to 300 ?C and its long term stability was verified. The chemical sensor determined the concentration of chemicals through evanescent field absorption. Techniques to increase the sensitivity of the evanescent field interaction such as tapering and coiling the fiber were successfully demonstrated. It was shown that the sensor is capable of quantitative measurements in both the mid-infrared and the near infrared regions of the spectrum. For the pressure sensor, a novel concept involving a pressure amplifier was investigated. While the basic idea was found to work, technical difficulties prevented the demonstration of a sensor capable of quantitative pressure measurements. As a result, the final combined probe contained only a temperature sensor and a chemical sensor. Under this program not only was the technical feasibility of a dual temperature/chemical sensor demonstrated, so were those of two ancillary devices. The first is a scan-and-dwell fiber optic mid-IR spectrometer specifically designed for process control applications. Also, a versatile high-brightness fiber optic light source with interchangeable emitting elements to cover different spectral regions has been demonstrated. The commercial potentials of the complete system as well as the individual components are being actively explored now.

Kennedy, Jermaine L

2009-03-12

109

Spatio-temporal noise and drift in fiber optic distributed temperature sensing  

International Nuclear Information System (INIS)

Distributed temperature sensing (DTS) allows for simultaneous measurement at many remote locations along an optical fiber probe and is a valuable tool in a broad range of applications, such as downhole oil production, dike structural monitoring or fire protection. The specific requirements on spatial, temporal and temperature resolution and on absolute measurement uncertainty vary with the applications. We investigate the spatio-temporal noise and drift properties of two exemplary Raman backscatter DTS systems and discuss the effect of spatial and temporal data averaging. An Allan deviation analysis provides insight into the optimal degree of averaging for a given distance range along the fiber probe. A temperature calibration procedure is employed to retrieve the temperature sensitivity of the DTS system and to compensate for the systematic spatial slope of recorded DTS temperature measurement traces. In response to small temperature steps of a thermally homogeneous and stable water bath environment, we observe a temperature resolution of approximately 0.05 °C at a chosen 1000 m sampling distance along the fiber probe

110

A tactile sensing element based on a hetero-core optical fiber for force measurement and texture detection  

Science.gov (United States)

Tactile sensing technology can measure a given property of an object through physical contact between a sensing element and the object. Various tactile sensing techniques have been developed for several applications such as intelligent robots, tactile interface, medical support and nursing care support. A desirable tactile sensing element for supporting human daily life can be embedded in the soft material with high sensitivity and accuracy in order to prevent from damaging to human or object physically. This report describes a new tactile sensing element. Hetero-core optical fibers have high sensitivity of macro-bending at local sensor portion and temperature independency, including advantages of optical fiber itself; thin size, light weight, flexible transmission line, and immunity to electro-magnetic interference. The proposed tactile sensing element could detect textures of touched objects through the optical loss caused by the force applied to the sensing element. The characteristics of the sensing element have been evaluated, in which the sensing element has the monotonic and non-linear sensitivity against the normal force ranged from 0 to 5 N with lower accuracy than 0.25 dB. Additionally, texture detection have been successfully demonstrated in which small surface figures of 0.1 mm in height were detected with spatial resolution of 0.4 mm.

Yamazaki, Hiroshi; Koyama, Yuya; Watanabe, Kazuhiro

2014-05-01

111

Behavior of Random Hole Optical Fibers under Gamma Ray Irradiation and Its Potential Use in Radiation Sensing Applications  

OpenAIRE

Effects of radiation on sensing and data transmission components are of greatinterest in many applications including homeland security, nuclear power generation, andmilitary. A new type of microstructured optical fiber (MOF) called the random hole opticalfiber (RHOF) has been recently developed. The RHOFs can be made in many differentforms by varying the core size and the size and extent of porosity in the cladding region.The fibers used in this study possessed an outer diameter of 110 ÃŽÂ...

Anbo Wang; Garland, Marc A.; Gary Pickrell; Bassam Alfeeli

2007-01-01

112

Fiber optic distributed temperature sensing for the determination of the nocturnal atmospheric boundary layer height  

Directory of Open Access Journals (Sweden)

Full Text Available A new method for measuring air temperature profiles in the atmospheric boundary layer at high spatial and temporal resolution is presented. The measurements are based on Raman scattering distributed temperature sensing (DTS with a fiber optic cable attached to a tethered balloon. These data were used to estimate the height of the stable nocturnal boundary layer. The experiment was successfully deployed during a two-day campaign in September 2009, providing evidence that DTS is well suited for this atmospheric application. Observed stable temperature profiles exhibit an exponential shape confirming similarity concepts of the temperature inversion close to the surface. The atmospheric mixing height (MH was estimated to vary between 5 m and 50 m as a result of the nocturnal boundary layer evolution. This value is in good agreement with the MH derived from concurrent Radon-222 (222Rn measurements and in previous studies.

C. A. Keller

2011-02-01

113

The strain field method for structural damage identification using Brillouin optical fiber sensing  

Science.gov (United States)

The theory of the strain field (SF) method using Brillouin optical fiber sensing (BOFS) is proposed for structural damage identification in this paper. Field test verification of this method was carried out by implementing a destructive loading test to an existing prestressed concrete bridge. A series of structural damage scenarios were thus produced for identification. A sub-matrix featuring the damage scenarios was first extracted from the space-time matrix to obtain the strain field distribution in space-time coordinates. Furthermore, other feature extraction operations, including row vector extraction, column vector extraction and boundary extraction, were performed to characterize the structural damage behavior and damage evolution patterns. Finally, damage localization and quantification were successfully implemented in both space and time domains in terms of a damage index vector array. The investigation results demonstrated the SF method using BOFS is a feasible and efficient approach for structural damage identification.

Zhang, Wei; Shi, Bin; Zhang, Yu-Feng; Liu, Jie; Zhu, You-Qun

2007-06-01

114

Development of a frequency-tunable optical phase lock loop (OPLL) for high resolution fiber optic distributed sensing  

Science.gov (United States)

We report on the development of a precision-tunable, dual wavelength, optical light source suitable for high performance fiber optic Brillouin scattering distributed sensing. The design is based on an Optical Phase Locked Loop (OPLL) system using novel narrow linewidth, low frequency noise and high stability PLANEX external cavity semiconductor. The inherent wavelength stability of PLANEX lasers (typically an order of magnitude better that any DFB laser on the market) enable the OPLL to operate continuously over a wide ambient temperature range without degradation in wavelength locking performance. The OPLL architecture is implemented with polarization maintaining (PM) components and has a very low beat frequency jitter on the order of few kHz. The OPLL frequency tuning range is between 8 and 14 GHz, with fast tuning of sweep steps on the order of 100 ?sec. Such a frequency tuning range covers practically all corresponding temperature and strain sensing applications based on the measurement of the frequency shift produced by spontaneous or stimulated Brillouin scattering, and thus is a versatile and enabling technology for both BOTDA/BOTDR distributed sensing systems.

Kuperschmidt, Vladimir; Stolpner, Lew; Mols, Peter; Alalusi, Mazin; Mehnert, Axel; Barsan, Radu; Ansari, Farhad

2011-04-01

115

A Fourier domain mode-locked fiber laser based on dual-pump fiber optical parametric amplification and its application for a sensing system  

International Nuclear Information System (INIS)

A Fourier domain mode-locked (FDML) fiber laser based on dual-pump fiber optical parametric amplification (FOPA) is proposed and demonstrated. The output spectrum of the proposed FDML fiber laser covers a sweeping wavelength range from 1540.8 to 1559.8 nm with a sweeping frequency of 31.688 kHz. A comparison of two FDML fiber lasers which are based on dual-pump FOPA and one-pump FOPA is also presented. A novel sensing system based on the FDML laser and a fiber Bragg grating, by which the sensing signal can be measured in the time domain instead of the frequency domain, is also demonstrated. (paper)

116

Optical Fiber Distributed Sensing System Applied in Cement Concrete Commixture Research  

Directory of Open Access Journals (Sweden)

Full Text Available DTS are unique optical-fiber distributed systems for measuring of temperature or mechanical tension. These systems use non-linear properties of optical fibers. Optical fiber can therefore be used not only for telecommunication purposes, as is currently the case, but also as a sensor. Optical fiber used by the DTS system can be therefore imagine as thousands of sensors placed along the route, taking all advantages of optical fiber, such as resistance to electromagnetic radiation, safe use in flammable and explosive environments, resistance to aggressive environments, small sizes, easy installation and maintenance-free operation. The properties of DTS system mentioned above seem to be ideal for detailed mapping of the hydration heat of concrete mix in the transition to a rigid structure. Values based on measurements will be used to better understanding of the processes inside the concrete mixture (individual samples and will serve to develop better and more durable mixture.

P. Koudelka

2010-04-01

117

A Finite Element Analysis of Fiber Optic Acoustic Sensing Mandrel for Acoustic pressure with Increased Sensitivity  

Directory of Open Access Journals (Sweden)

Full Text Available - This paper investigates the influence of material properties on the performance of an optical fiber wound mandrel composite fiber optic interferometer mandrel by using the ANSYS Cad tool, The acoustic sensitivity of an optical fiber considered analytically, High sensitivity obtained with low young modulus, very thick polymer coatings. The thick coating realized by embedding optical fiber in polyurethane. A flexible composite fiber-optic interferometric acoustic sensor has been developed by wrapping single mode fiber in a winding manner and then embedding a fiber in a thin polyurethane layer. The acoustic sensitivity has to be found more in a frequency range of (2.5-5.0 KHz. In this paper we studied the structural and material properties of a mandrel sensor with foaming layer in such way to get the optimal performance. The sensor was found to be compatible with water. Also the performance of optical fiber is analytically verified using the MATLAB software. In this paper the design was simulated in ANSYS Cad Tool, to verify the sensitivity of the Optical Mach-Zehnder Interferometric Sensor for increased sensitivity. The main objective and focus of the above work is concentrated on choosing the optimal foaming layer material by varying the Young Modulus E to choose the perfect foaming material for implementing in the design of mandrel.

Prashil M. Junghare

2013-09-01

118

Motion compensation in distributed fiber optic sensing via optical frequency domain reflectometry  

Science.gov (United States)

We demonstrate a novel algorithm for removing adverse effects of motion in distributed strain measurements via Optical Frequency Domain Reflectometry (OFDR), using Rayleigh backscatter from low-bend loss fiber as the transducer. Vibration amplitudes and frequencies of 2.5 Gs and up to 50 Hz, respectively, were corrected for in real-time while measuring up to 10,000 microstrain. Results show 99.3% recovery of motion-affected strain data while maintaining 0.3% accuracy and 5 mm spatial resolution. Measurement acquisition rates were 23.8 Hz and 100 Hz. These results demonstrate that OFDR may be used in dynamic environments to provide accurate and high-resolution, distributed strain measurements.

Bos, Joseph J.; Abdul Rahim, Nur Aida

2014-05-01

119

A Bragg Wavelength-Insensitive Fiber Bragg Grating Ultrasound Sensing System that Uses a Broadband Light and No Optical Filter  

OpenAIRE

An optical filter is incorporated in a conventional ultrasound detection system that uses a fiber Bragg grating (FBG) and broadband light source, to demodulate the FBG sensor signal. A novel ultrasound sensing system that does not require an optical filter is presented herein. Ultrasound could be detected via the application of signal processing techniques, such as signal averaging and frequency filters, to the photodetector output that corresponds to the intensity of the reflected light from...

Hiroshi Tsuda

2011-01-01

120

Effects of elongation on polymer optical fiber power losses for sensing purposes  

Science.gov (United States)

In this work, we explore the variation of power losses of PMMA-core plastic optical fiber through tensile tests. Experimental results of received optical power during elastic and plastic deformation process demonstrate the feasibility of POFs as simple intensity-based fiber-optic sensors for Structural Health Monitoring applications beyond complex schemes. A theoretical approach of the POF behavior versus strain is also provided.

Montero, D. S.; Torres, J. C.; Zahr-Viñuelas, J.; Pérez Castellanos, J. L.; Vázquez, C.

2014-05-01

121

Research on the feature extraction and pattern recognition of the distributed optical fiber sensing signal  

Science.gov (United States)

In this paper, feature extraction and pattern recognition of the distributed optical fiber sensing signal have been studied. We adopt Mel-Frequency Cepstral Coefficient (MFCC) feature extraction, wavelet packet energy feature extraction and wavelet packet Shannon entropy feature extraction methods to obtain sensing signals (such as speak, wind, thunder and rain signals, etc.) characteristic vectors respectively, and then perform pattern recognition via RBF neural network. Performances of these three feature extraction methods are compared according to the results. We choose MFCC characteristic vector to be 12-dimensional. For wavelet packet feature extraction, signals are decomposed into six layers by Daubechies wavelet packet transform, in which 64 frequency constituents as characteristic vector are respectively extracted. In the process of pattern recognition, the value of diffusion coefficient is introduced to increase the recognition accuracy, while keeping the samples for testing algorithm the same. Recognition results show that wavelet packet Shannon entropy feature extraction method yields the best recognition accuracy which is up to 97%; the performance of 12-dimensional MFCC feature extraction method is less satisfactory; the performance of wavelet packet energy feature extraction method is the worst.

Wang, Bingjie; Sun, Qi; Pi, Shaohua; Wu, Hongyan

2014-09-01

122

SPR based fiber optic sensor for refractive index sensing with enhanced detection accuracy and figure of merit in visible region  

Science.gov (United States)

We, theoretically, propose a surface plasmon resonance (SPR) based indium tin oxide (ITO)-silver (Ag) coated fiber optic sensing probe for refractive index sensing in visible regime of the electromagnetic spectrum. A comparative study of ITO+Ag coated probe with Ag coated probe and with ITO coated probe using their respective optimized film thicknesses is carried out. We show that the proposed probe is endowed with the better sensitivity characteristic of ITO and better detection accuracy (DA) characteristic of Ag, and can sense change in refractive index with enhanced DA and figure of merit (FOM) in the visible region.

Mishra, Akhilesh K.; Mishra, Satyendra K.; Gupta, Banshi D.

2015-06-01

123

Development of fiber optic ferrule-top cantilevers for sensing and beam-steering applications  

Science.gov (United States)

Ferrule-top (FT) cantilevers are a new generation of all optical micromechanical sensors obtained by carving microstructures on the top of ferrule terminated fibers. In this paper, we will demonstrate how this plug and play design can be used for the development of a new generation of sensors and actuators for harsh environments, where commercially available devices would be prone to failure. Ferrule-top sensors can work in two main modes - static and dynamic. The static mode is based on recording elastic deflection of the cantilever; the dynamic mode relies on tracking changes in its mechanical properties (resonance frequency, quality factor). Depending on the application, one can choose which mode is most suitable or combine both to achieve best performance. We will illustrate the relation between specific measured quantity (humidity, flow) and the behavior of the sensor. Further, we will show the setup in which the sensor can be actuated using light, giving the possibility to excite the cantilever without any electronics on the sensing head. This technique might by use for the development of fully optical beamsteering microdevices.

Gruca, G.; Chavan, D.; Cipullo, A.; Babaei Gavan, K.; De Filippis, F.; Minardo, A.; Rector, J.; Heek, K.; Zeni, L.; Iannuzzi, D.

2012-04-01

124

Research on sensing characteristics of low-finesse fiber-optic Fabry-Perot cavity  

Science.gov (United States)

The Low-Finesse Fabry-Perot(F-P) cavity, as a kind of fiber-optic sensor probe frequently used, can be applied to detect physical parameters of strain, temperature, acoustic wave, pressure, and so on, and is an important optical sensing component. In this paper, sensing properties of low-finesse F-P cavity is deeply and systemically analyzed. At first, the interference principle of F-P cavity is illuminated from three aspects which include the distribution of light power, the characteristic of interference fringe and the sensitivity. Considering the spectrum of incident beam obeys a Gaussian distribution, the intensity distribution of reflected beam is approximate to a cosine function within a Gaussian envelope and the visibility of interference fringes follows a Gaussian distribution also. Moreover, the operating point of low finesse F-P cavity must be held near the quadrature-point for the maximum sensitivity. The operating characteristic of FP cavity is analyzed from three aspects including linearity, property of temperature and contrast of fringe. Analyzing results show that the F-P cavity can offer the linearity of 2.2%, and the fringe contrast drops as the length of F-P cavity increases. In addition, the F-P cavity is insensitive to the change of environmental temperature and possesses an excellent capability to suppress the temperature disturbance. Finally, a test scheme is established to verify the sensor performance of F-P probe. Test results indicate that the F-P cavity offers the sensitivity of 7.5V/um and the measuring accuracy of 9.4nm, and can well satisfies the practical requirement.

Zhao, Jian-ghai; Ye, Xiao-dong; Sun, Shao-min; Xu, Lin-sen

2012-10-01

125

Using ac-field-induced electro-osmosis to accelerate biomolecular binding in fiber-optic sensing chips with microstructures.  

Science.gov (United States)

This article reports the use of ac-field-induced charges at the corners of microstructures on fiber-optic sensing chips to generate electro-osmotic vortex flows in flow cell channels that can accelerate solute binding on the fiber. The sensing chip made of a cyclic olefin copolymer COC substrate contained a flow cell channel of dimensions 15 mm x 1 mm x 1 mm. A partially unclad optical fiber was placed within the channel. Relief-like strip structures of 25-mum thickness fabricated on the channel bottom were produced with an injection-molding process. The external electric field lines penetrating through the corners of the plastic microstructures induce charges on the corner surfaces to build up electrical double layers. When a high-frequency ac field (approximately 100 kHz) is used to flip the field polarities quickly, neutralization of the induced charge cannot be accomplished. The electrical double layer is therefore sustained. When absorbed charges in the double layer are driven by the external field, electro-osmotic flows are generated. The unclad portion of the fiber was coated with biotin-functionalized gold nanoparticles. The streptavidin solution was filled in the channel from the feeding tube, and the ac field (approximately 50 V/cm) was subsequently turned on for 30 s. The ac-field-induced electro-osmotic flows can accelerate solute transport in the sensing channel to enhance the binding kinetics of streptavidin molecules with biotin probes implanted on the gold nanoparticle surface. As a result, the fiber-optic localized plasmon resonance (FO-LPR) sensing signal becomes steady as soon as the external field is turned off. In contrast, the signal cannot reach steady state until 200-300 s in a typical static sensing cell. A significant reduction in the sensing response time is demonstrated. The binding assay of streptavidin with immobilized biotin on gold nanoparticle-coated sensing fibers was validated using this mixing device. The detection limit for streptavidin of approximately 10(-11) M is close to the reported values obtained using static cells. Similarly, the sensing response time of an orchid Odontoglossum ringspot virus (ORSV) sample was reduced from 1000 to 330 s when an external field was applied to mix the fluid for 60 s, even though the detection limit was maintained. PMID:20055421

Chuang, Yen; Lee, Chia-Yu; Lu, Sin-Hong; Wang, Shau-Chun; Chau, Lai-Kwan; Hsieh, Wen-Hsin

2010-02-01

126

An optical modulation method to suppress stimulated Brillouin scattering and the phase noise in a remote interferometric fiber sensing system  

Science.gov (United States)

A novel optical modulation method for stimulated Brillouin scattering (SBS) and the phase noise suppression in a remote interferometric fiber sensing system is proposed. Compared to the conventional phase modulation method to suppress SBS with only one phase modulation signal, another phase modulation signal with ? shift is applied at the output end of the fiber, which converts the generated multi-frequency light to single-frequency light. Therefore the method can suppress not only SBS but also the phase noise induced by linewidth broadening owing to the first phase modulation. As a result, the method can keep the system a low phase noise level with a higher input power, which overcomes the conventional drawback of linewidth broadening. The results show a good reference to the design of remote interferometric fiber sensing systems.

Hu, Xiaoyang; Chen, Wei; Fan, Liwen; Meng, Zhou; Chen, Mo

2014-10-01

127

Fiber Optical Micro-detectors for Oxygen Sensing in Power Plants  

Energy Technology Data Exchange (ETDEWEB)

A reflection mode fiber optic oxygen sensor that can operate at high temperatures for power plant applications is being developed. The sensor is based on the {sup 3}O{sub 2} quenching of the red emission from hexanuclear molybdenum chloride clusters. Our approach towards immobilizing the potassium salt of the molybdenum cluster, K{sub 2}Mo{sub 6}Cl{sub 14}, at the far end of an optical fiber is to embed the cluster in a thermally cured sol-gel matrix particle. This particle-in-binder approach affords fibers with greatly improved mechanical properties, as compared to previous approaches. The sensor was characterized in 2-21% gas phase oxygen at 40, 70 and 100 C. These are promising results for a high temperature fiber optical oxygen sensor based on molybdenum chloride clusters.

Gregory L. Baker; Ruby N. Ghosh; D.J. Osborn; Po Zhang

2006-06-30

128

Optimized design and simulation of high temperature pressure pipeline strain monitoring with optical fiber sensing technology  

Science.gov (United States)

High temperature pressure piping have been applied widely in the chemical industry, the petroleum enterprises and the electrical power plants, and corresponding accidents happened frequently every year owing to the pipeline leakage and explosion. By massive accident statistics and analysis, the high temperature creep and the pipeline inside wall corroding are the main causes to result in the pipeline leakage and explosion accident. By real time sensing the strain change of pipeline outer surface, the online working status of the high temperature pipeline could be monitored and the leakage and explosion accidents would be avoided. Now several methods can be considered to sensing and monitoring the strain change of the high temperature pipeline surface, including Electricity sensor examination method, ultrasonic wave examination method and infrared thermal imagery examination method. After careful analysis and contrast, Electricity sensor examination method was given up for it couldn't be working steadily under high temperature conditions and easily excitated electric sparks which would result in flammable explosive danger in chemical industry and petroleum enterprises. Ultrasonic wave examination method and infrared thermal imagery examination method could avoid the shortages of Electricity sensor examination method based on the non-destructive examination theory, but the ultrasonic wave method could be applied only in examining the pipeline wall thickness, the inside wall crack as well as the material air bubble flaws restricted in its working principle. Consequently ultrasonic wave method examination method wasn't suitable to sense and monitor the strain change of the high temperature pipeline surface; Infrared thermal imagery examination method has low sensing resolution and can only examine internal etching pit and wall thickness attenuating, so it is unable to examine the pipeline surface strain change on time. Therefore three reported real-time examination methods mentioned above cannot satisfy the strain change monitoring of high temperature pressure piping. In this paper a novel method is presented using optical Fiber Bragg Grating sensor to carry on the real-time monitoring of the high temperature pressure piping surface strain change. firstly the stress and strain analysis of the high temperature pressure piping surface is given based on the established theoretical model, then optimized design and simulation is accomplished with computer ANSYS software. In the end a optimized set-up is put forward and discussed.

Zhang, Feng; Liu, Yueming; Lou, Jun

2011-08-01

129

Evaluation of fiber optic distributed temperature sensing in characterization of borehole fractures: a laboratory experiment  

Science.gov (United States)

Mapping of bedrock fractures in boreholes and the contribution of main fractures to groundwater flow have long been a significant challenge in the geosciences field. Advanced techniques such as formation micro-imager (FMI) are able to detect the location of downhole fractures and to characterise their properties, such as aperture and orientation. However, these techniques have not been designed to estimate flow from individual fractures and are, in many cases, economically unjustified. In recent years, Fiber Optic Distributed Temperature Sensing (DTS) has been used to detect the location of active fractures and their contribution to groundwater flow, however; the technique has not been evaluated in a controlled environment and the limitations of the technique have yet to be identified. For that reason, a fractured rock borehole with active fractures was simulated in a lab-scale experiment. A structure with two fractures was built in a cylindrical configuration around the borehole and placed inside a cylindrical reservoir. A coiled fibre optic cable was inserted in the centre of the borehole. In order to simulate groundwater interactions, water with distinct temperature was added to the reservoir. During tests, water from the borehole in the centre was pumped out of the system, while the fiber optic DTS recorded the temperature response. The location of the artificial fractures and their contribution to the flow rate were determined through analysis of the measured temperature data. The results show that for the experimental setup, the locations of the fractures are most easily detected from the early times of the temperature response. As the water with different temperature from the reservoir flows into the borehole, it changes the borehole temperature starting from around the fracture locations. With time, this anomaly disappears and the borehole temperature reaches a new steady state condition. The contribution of each fracture to the pumping flow can then be identified from a combination of early time temperature responses and the new steady state temperature inside the borehole. The experiment also revealed that for certain combinations of parameters (temperature difference between water in borehole and fracture, pumping flow rate and aperture of the fracture), there exists a threshold below which fracture locations and flow rates cannot be accurately detected by measuring the temperature response.

Roshan, Hamid; Queen, Gabriella; Andersen, Martin S.; Acworth, Ian R.

2014-05-01

130

Analytical study of Bragg-grating fiber-optic filters for DWDM and temperature-sensing applications  

Science.gov (United States)

This work is concerned with the applications of Bragg-grating fiber-optic filters. First, on the basis of recently pointed out discrepancies between different formulations of the coupled-mode theory, we revisit the design process of devices intended for amplified spontaneous emission noise filtering in DWDM systems. Next, the use of these same basic filter structures in temperature sensing is discussed. The proposed device employs a dual-wavelength measurement scheme of the optical power being transmitted by the Bragg filter, thereby tracking temperature variations while simultaneously canceling spurious readings due to random optical power fluctuations.

de Francisco, Carlos A.; Camargo Silva, Milson T.; Romero, Murilo A.

2002-07-01

131

Development of optical fiber sensing instrument for aviation and aerospace application  

Science.gov (United States)

Optical fiber sensor has great advantage for applications dealing with extreme environment. We developed a high precision optical pressure sensor for aviation industry. The optical pressure sensor is based on two-beam interference of microcavity and is fabricated with Micro-electromechanical systems (MEMS) and laser fusion technology. The cavity length variation resulting from external pressure is demodulated with spatial polarization low coherence interference unit and a high stable phase demodulation algorithm. The effect of light source output parameter is also investigated. We carried out research on optical fiber strain, temperature and acoustic vibration sensor for aerospace application. The optical fiber sensors for strain and temperature measurement are based on fiber Bragg grating(FBG).Both bare FBG and packaged FBG performances under cryogenic temperature and high vacuum are investigated. An eight-channel parallel FBG wavelength interrogator is developed. The optical fiber acoustic vibration sensor is based on two-beam interference of microcavity and use intensity demodulation method for high speed response. The mutiple-parameter and multiplepoint measurement instrument is successfully applied to status monitoring of water sublimator.

Jiang, Junfeng; Liu, Tiegen; Liu, Kun; Wang, Shuang; Yin, Jinde; Zhao, Bofu; Zhang, Jingchuang; Song, Luyao; Zhao, Peng; Wu, Fan; Zhang, Xuezhi

2013-12-01

132

A surface plasmon resonance probe without optical fibers as a portable sensing device  

International Nuclear Information System (INIS)

A surface plasmon resonance (SPR) sensor integrating a small sensor probe, a laser emission diode, a photo detector, and a polarizer was developed as a portable sensing device. The sensor probe was made with a glass cylinder, 50 mm long and 1.5 mm in diameter, that was connected directly to a beam splitter without optical fibers. The SPR spectrum obtained with this probe system showed a 10% reflectivity minimum at 690 nm. Shifts of the SPR spectrum induced by refractive index (RI) changes in the sample were measured by detecting the reflection light intensity at 670 nm. When the sensitivity was compared using a BIAcoreTM SPR instrument, the lowest sensor response of 1 mV observed with the SPR probe system coincided with 1.4 x 10-6 of the RI changes. The RI resolution of the SPR probe was estimated with experimentally evaluated noise on the signal, and, consequently, it was concluded that the RI resolution was 1.2 x 10-5. Moreover, immunoreaction was demonstrated with adsorbed bovine serum albumin (BSA) and anti-BSA antibody as an analyte. As a result, 50 ng mL-1 of the lower detection limit was estimated

133

Field Measurement of Fracture/Matrix Heat Exchange using Fiber Optic Distributed Temperature Sensing  

Science.gov (United States)

Highly channelized flow in fractured geologic systems has been blamed for early thermal breakthrough and poor performance of geothermal circulation systems. An experiment is presented in which the effect of channelized flow on fluid/rock heat transfer is measured. Hot water was circulated between two wells (7-14 m separation) completed in a single bedding plane fracture. The elevation of rock matrix temperature was measured using Fiber Optic Distributed Temperature Sensing (DTS). Between wells with good hydraulic connection, heat transfer followed a classic dipole sweep pattern. Between wells with poor hydraulic connection, heat transfer was skewed toward apparent regions of higher transmissivity (or larger aperture). Heat transfer between fracture and matrix was compared with saline tracer circulated between the same wells. Saline distribution was imaged using surface Ground Penetrating Radar. The results suggest that flow channeling can have a significant impact on heat transfer efficiency even in single bedding plane fractures. Temperature rise in the rock matrix above a fracture as a function of time Map view comparison of heat exchange to ground penetrating radar reflection amplitude (a function of fracture aperture). Red is warmer rock, yellow is cooler.

Hawkins, A.; Becker, M. W.; Tsoflias, G. P.

2012-12-01

134

A surface plasmon resonance probe without optical fibers as a portable sensing device.  

Science.gov (United States)

A surface plasmon resonance (SPR) sensor integrating a small sensor probe, a laser emission diode, a photo detector, and a polarizer was developed as a portable sensing device. The sensor probe was made with a glass cylinder, 50mm long and 1.5mm in diameter, that was connected directly to a beam splitter without optical fibers. The SPR spectrum obtained with this probe system showed a 10% reflectivity minimum at 690 nm. Shifts of the SPR spectrum induced by refractive index (RI) changes in the sample were measured by detecting the reflection light intensity at 670 nm. When the sensitivity was compared using a BIAcore SPR instrument, the lowest sensor response of 1mV observed with the SPR probe system coincided with 1.4x10(-6) of the RI changes. The RI resolution of the SPR probe was estimated with experimentally evaluated noise on the signal, and, consequently, it was concluded that the RI resolution was 1.2x10(-5). Moreover, immunoreaction was demonstrated with adsorbed bovine serum albumin (BSA) and anti-BSA antibody as an analyte. As a result, 50 ng mL(-1) of the lower detection limit was estimated. PMID:18267148

Akimoto, Takuo; Wada, Syunsuke; Karube, Isao

2008-03-01

135

Bed conduction impact on fiber optic distributed temperature sensing water temperature measurements  

Science.gov (United States)

Error in distributed temperature sensing (DTS) water temperature measurements may be introduced by contact of the fiber optic cable sensor with bed materials (e.g., seafloor, lakebed, streambed). Heat conduction from the bed materials can affect cable temperature and the resulting DTS measurements. In the Middle Fork John Day River, apparent water temperature measurements were influenced by cable sensor contact with aquatic vegetation and fine sediment bed materials. Affected cable segments measured a diurnal temperature range reduced by 10% and lagged by 20-40 min relative to that of ambient stream temperature. The diurnal temperature range deeper within the vegetation-sediment bed material was reduced 70% and lagged 240 min relative to ambient stream temperature. These site-specific results illustrate the potential magnitude of bed-conduction impacts with buried DTS measurements. Researchers who deploy DTS for water temperature monitoring should understand the importance of the environment into which the cable is placed on the range and phase of temperature measurements.

O'Donnell Meininger, T.; Selker, J. S.

2015-02-01

136

FIBER OPTICAL MICRO-DETECTORS FOR OXYGEN SENSING IN POWER PLANTS  

Energy Technology Data Exchange (ETDEWEB)

A reflection mode fiber optic oxygen sensor that can operate at high temperatures for power plant applications is being developed. The sensor is based on the {sup 3}O{sub 2} quenching of the red emission from hexanuclear molybdenum chloride clusters. High temperature measurements of the emission of clusters in sol gel films show that the luminescence intensity from the films follow a 1/T relationship from room temperature to 150 C, and then declines at a slower rate at higher temperatures. The large number of photons available at 230 C is consistent with simple low cost optics for fiber optic probes based on the emission from clusters in sol gel films.

Gregory L. Baker; Ruby N. Ghosh; D.J. Osborn III

2004-10-01

137

FIBER OPTICAL MICRO-DETECTORS FOR OXYGEN SENSING IN POWER PLANTS  

International Nuclear Information System (INIS)

A reflection mode fiber optic oxygen sensor that can operate at high temperatures for power plant applications is being developed. The sensor is based on the 3O2 quenching of the red emission from hexanuclear molybdenum chloride clusters. High temperature measurements of the emission of clusters in sol gel films show that the luminescence intensity from the films follow a 1/T relationship from room temperature to 150 C, and then declines at a slower rate at higher temperatures. The large number of photons available at 230 C is consistent with simple low cost optics for fiber optic probes based on the emission from clusters in sol gel films

138

Temperature compensated magnetic field sensing using dual S-bend structured optical fiber modal interferometer cascaded with fiber Bragg grating.  

Science.gov (United States)

A temperature compensated magnetic field strength optical fiber sensor has been proposed and experimentally demonstrated. A fiber Bragg grating (FBG) is cascaded to modal interferometer (MI), which is fabricated by dual S-bend splicing between thin fiber (TF) and single mode fiber (SMF) with intentionally controlled misalignment between cores. We established a modified numerical model to describe the multi-mode interference of this exceptional S-bend and misalignment structure, together with the simulation based on beam propagation method to gain insight into its operation mechanism. The FBG is used to interrogate the temperature change, and then compensate the perturbation of temperature on transmission of the MI. Thanks to the proposed dual S-bend structure and the diameter-thinned TF used here; we have obtained high magnetic sensitivity of -0.0678 dB/Oe using only 4 mm TF after the elimination of ambient temperature change. PMID:25401898

Zhao, Zhiyong; Tang, Ming; Gao, Feng; Zhang, Peng; Duan, Li; Zhu, Benpeng; Fu, Songnian; Ouyang, Jun; Wei, Huifeng; Li, Jinyan; Shum, Perry Ping; Liu, Deming

2014-11-01

139

Fiber Optical Micro-detectors for Oxygen Sensing in Power Plants  

Energy Technology Data Exchange (ETDEWEB)

A reflection mode fiber optic oxygen sensor that can operate at high temperatures for power plant applications is being developed. The sensor is based on the {sup 3}O{sub 2} quenching of the red emission from hexanuclear molybdenum chloride clusters. Our approach towards immobilizing the potassium salt of the molybdenum cluster, K{sub 2}Mo{sub 6}Cl{sub 14}, at the far end of an optical fiber is to embed the cluster in a thermally cured sol-gel matrix particle. Due to the improved mechanical properties of this approach high temperature sensor measurements were performed up to 100 C. These are promising results for a high temperature fiber optical oxygen sensor based on molybdenum chloride clusters.

Gregory L. Baker; Ruby N. Ghosh; D. J. Osborn; Po Zhang

2006-09-30

140

Application of optical sensing technology to the civil engineering field with optical fiber strain measurement device (BOTDR)  

Science.gov (United States)

Nippon Telegraph and Telephone Corporation (NTT)has developed a device (BOTDR)for measuring the strain occurring in optical fibers as a means of monitoring the condition of optical fiber telecommunications cables.The authors are promoting development of a system that uses this device to measure and monitor structural and ground deformation. This paper first introduces the measurement principle of the strain measurement method using optical fibers (BOTDR method).It then presents case studies of application to the deformation of telecommunications tunnels,ground subject to landslides and so on,and also an outline of an automatic measuring system.

Komatsu, Koji; Fujihashi, Kazuhiko; Okutsu, Masaru

2002-09-01

141

The fiber-optic gyroscope: Challenges to become the ultimate rotation-sensing technology  

Science.gov (United States)

Taking advantage of the development of optical-fiber communication technologies, the fiber-optic gyroscope started to be investigated in the mid 1970s, opening the way for a fully solid-state rotation sensor. It was firstly seen as dedicated to medium-grade applications, but today, it reaches strategic-grade performance and surpasses its well-established competitor, the ring-laser gyroscope, in terms of bias noise and long-term stability. Further progresses remain possible, the challenge being the ultimate inertial navigation performance of one nautical mile per month corresponding to a long-term bias stability of 10-5°/h.

Lefèvre, Hervé C.

2013-12-01

142

Fiber optic calorimetry  

International Nuclear Information System (INIS)

A twin-bridge calorimeter using optical fiber as the sensor element was constructed and tested. This system demonstrates the principle and capability of using optical fibers for heat-flow measurements of special nuclear material. This calorimeter uses piezoelectric-generated phase-carrier modulation with subsequent electronic signal processing to allow phase shifts as small as 1 microrad to be measured. The sensing element consists of 21-m lengths of single-mode optical fiber wrapped around sample and reference chambers. The sensitivity of the calorimeter was determined to be 74 rad of phase shift per mW of thermal power. One milliwatt of thermal power is equivalent to 400 mg of plutonium (6% 240Pu). The system noise base was about 0.2 rad, equivalent to about 1 mg of plutonium

143

Fiber Optic Calorimetry  

International Nuclear Information System (INIS)

A twin-bridge calorimeter using optical fiber as the sensor element was constructed and tested. This system demonstrates the principle and capability of using optical fibers for heat-flow measurements of special nuclear material. This calorimeter uses piezoelectric-generated phase-carrier modulation with subsequent electronic signal processes to allow phase shifts as small as 1 microradian (microrad) to be measured. The sensing element consists of 21-m lengths of single-mode optical fiber wrapped around sample and reference chambers. The sensitivity of the calorimeter was determined to be 74 radians (rad) of phase shift per milliwatt of thermal power. One milliwatt of thermal power is equivalent to 400 mg of plutonium (6% 240Pu). The system noise base was about 0.2 rad, equivalent to about 1 mg of plutonium

144

Fiber Optical Micro-detectors for Oxygen Sensing in Power Plants  

Energy Technology Data Exchange (ETDEWEB)

A reflection mode fiber optic oxygen sensor that can operate at high temperatures for power plant applications is being developed. The sensor is based on the {sup 3}O{sub 2} quenching of the red emission from hexanuclear molybdenum chloride clusters. Previously we described a particle-in-binder approach to immobilizing the potassium salt of a molybdenum cluster, K{sub 2}Mo{sub 6}Cl{sub 14}, at the tips of optical fibers. Compared to previous methods, the particle-in-binder approach affords fibers with greatly improved mechanical properties. We have extensively characterized two fiber sensors at high temperature. We obtain quenching ratios between pure nitrogen and 21% oxygen as high as 3.9 x at 70 C. For the first sensor at 60 C we obtained a {+-} 1% variation in the quenching ratio over 6 cycles of measurement, and monitored the device performance over 23 days. We were able to operate the second sensor continuously for 14 hours at 70 C, and the sensor quenching ratio was stable to 5% over that time period. These are promising results for a high temperature fiber optical oxygen sensor based on molybdenum chloride clusters.

Gregory L. Baker; Ruby N. Ghosh; D.J. Osborn III; Po Zhang

2006-01-01

145

Detection of plasma equilibrium shifts with fiber-optic sensing of image currents  

International Nuclear Information System (INIS)

Plasma shifts generate opposite-polarity net shell image currents at diametrically opposed shell locations. In theory these image currents can be detected by Faraday rotation fiber-optic current sensors wound around the shell sections. In practice the validity of the measurement depends on the extent of suppression of the linear birefringence induced by the fiber coil bending and lateral pressure. Circular birefringence bias twist of 60 turns/m of 125-?m o.d. single-mode fiber is sufficient for 2-in. radii of curvature bends, in agreement with theory, while 100 turns/m of 80-?m o.d. fiber have not been successful with 1-in. radii of curvature, contrary to calculations. Different means for further suppression of linear birefringence are discussed

146

Pulsed time-of-flight radar for fiber-optic strain sensing  

Science.gov (United States)

This article describes a fiber-optic interrogation device based on the pulsed time-of-flight technique. The apparatus is capable of measuring time delays between wideband reflectors, such as connectors, along a fiber path with a precision of about 280fs (rms value) and a spatial resolution of about 3ns (0.30m) in a measurement time of 25ms. Potential application areas include measuring integral strain and its derivatives such as cracks, deflections, and displacements, particularly in large civil engineering and composite structures. The operation and basic blocks of the measurement system are presented in detail together with measurement results obtained in laboratory and field conditions. It is shown that by using a fiber loop sensor with a reference fiber, it is possible to achieve a strain precision below 1?strain and a measurement frequency of 4Hz. System performance proved adequate for the study of both static and dynamic phenomena in a bridge deck.

Lyöri, Veijo; Kilpelä, Ari; Duan, Guoyong; Mäntyniemi, Antti; Kostamovaara, Juha

2007-02-01

147

Pulsed time-of-flight radar for fiber-optic strain sensing.  

Science.gov (United States)

This article describes a fiber-optic interrogation device based on the pulsed time-of-flight technique. The apparatus is capable of measuring time delays between wideband reflectors, such as connectors, along a fiber path with a precision of about 280 fs (rms value) and a spatial resolution of about 3 ns (0.30 m) in a measurement time of 25 ms. Potential application areas include measuring integral strain and its derivatives such as cracks, deflections, and displacements, particularly in large civil engineering and composite structures. The operation and basic blocks of the measurement system are presented in detail together with measurement results obtained in laboratory and field conditions. It is shown that by using a fiber loop sensor with a reference fiber, it is possible to achieve a strain precision below 1 microstrain and a measurement frequency of 4 Hz. System performance proved adequate for the study of both static and dynamic phenomena in a bridge deck. PMID:17578137

Lyöri, Veijo; Kilpelä, Ari; Duan, Guoyong; Mäntyniemi, Antti; Kostamovaara, Juha

2007-02-01

148

Advantage of multi-mode sapphire optical fiber for evanescent-field SERS sensing.  

Czech Academy of Sciences Publication Activity Database

Ro?. 39, ?. 20 (2014), 5822-5825. ISSN 0146-9592 R&D Projects: GA MŠk(CZ) LH11038 Institutional support: RVO:67985882 Keywords : Fiber optics sensors * Backscattering * Nanomaterials Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 3.179, year: 2013

Chen, H.; Tian, F.; Chi, J.; Ka?ka, Ji?í; Du, H.

2014-01-01

149

Investigating Into Sensing Properties of Fiber Optic Thermo-Hygrometers for CMS  

CERN Document Server

A set of optical fiber sensors based on FBG-technology are to be installed in the CMS experiment for the first time. These sensors consists of coupled pairs of temperature and relative humidity sensors and this report outlines the calibration performed primarily on the temperature sensors in preparation of the installation.

Wallangen, Veronica

2013-01-01

150

High-Tg TOPAS microstructured polymer optical fiber for fiber Bragg grating strain sensing at 110 degrees  

DEFF Research Database (Denmark)

We present the fabrication and characterization of fiber Bragg gratings (FBGs) in an endlessly single-mode microstructured polymer optical fiber (mPOF) made of humidity-insensitive high-Tg TOPAS cyclic olefin copolymer. The mPOF is the first made from grade 5013 TOPAS with a glass transition temperature of Tg = 135°C and we experimentally demonstrate high strain operation (2.5%) of the FBG at 98°C and stable operation up to a record high temperature of 110°C. The Bragg wavelengths of the FBGs are around 860 nm, where the propagation loss is 5.1dB/m, close to the fiber loss minimum of 3.67dB/m at 787nm.

Markos, Christos; Stefani, Alessio

2013-01-01

151

The fiber-optic gyroscope, a century after Sagnac's experiment: The ultimate rotation-sensing technology?  

Science.gov (United States)

Taking advantage of the development of optical-fiber communication technologies, the fiber-optic gyroscope (often abbreviated FOG) started to be investigated in the mid-1970s, opening the way for a fully solid-state rotation sensor. It was firstly seen as dedicated to medium-grade applications (1 ° / h range), but today, it reaches strategic-grade performance (10-4 ° / h range) and surpasses its well-established competitor, the ring-laser gyroscope, in terms of bias noise and long-term stability. Further progresses remain possible, the challenge being the ultimate inertial navigation performance of one nautical mile per month corresponding to a long-term bias stability of 10-5 ° / h. This paper is also the opportunity to recall the historical context of Sagnac's experiment, the origin of all optical gyros. xml:lang="fr"

Lefèvre, Hervé C.

2014-12-01

152

FIBER OPTICAL MICRO-DETECTORS FOR OXYGEN SENSING IN POWER PLANTS  

Energy Technology Data Exchange (ETDEWEB)

A reflection mode fiber optic oxygen sensor that can operate at high temperatures for power plant applications is being developed. The sensor is based on the {sup 3}O{sub 2} quenching of the red emission from hexanuclear molybdenum chloride clusters. Alkali salts of Mo{sub 6}Cl{sub 12} were synthesized and heated to 280 C for one hour in air. Optical measurements of the thermally treated material confirm the potential of the salts as lumophores in high temperature fiber optic sensors. In addition sol-gel films containing Mo{sub 6}Cl{sub 12} were dip coated on quartz substrates and heated at 200 C for one hour. Conditions were developed for successfully immobilizing monomeric complexes that are compatible with sol-gel processing.

Gregory L. Baker; Ruby N. Ghosh; D.J. Osborn III

2004-07-01

153

Gas chromatographic sensing on an optical fiber by mode-filtered light detection.  

Science.gov (United States)

A chemical sensor for gas phase measurements is reported which combines the principles of chemical separation and fiber optic detection. The analyzer incorporates an annular column Chromatographic sensor, constructed by inserting a polymer-clad optical fiber into a silica capillary. Light from a helium-neon laser is launched down the fiber, producing a steady intensity distribution within the fiber, but a low background of scattered light. When sample vapor is introduced to the sensor, and an analyte-rich volume interacts with the polymer cladding, Chromatographic retention is observed simultaneously with a change in the local refractive index of the cladding. An increase in cladding refractive index (RI) causes light to be coupled out of the fiber, with detection at a right-angle to the annular column length to provide optimum S/N ratio. This detection mechanism is called mode-filtered light detection. We report a gas Chromatographic separation on a 3.1 m annular column (320 microm i.d. silica tube, 228 microm o.d. fiber with a 12 microm fluorinated silicone clad) of methane, benzene, butanone and chlorobenzene in 6 min. The annular column length was reduced to 22 cm to function as a sensor, with selected organic vapors exhibiting unique retention times and detection selectivity. The detection selectivity is determined by the analyte RI and the partition coefficient into the cladding. The calculated limit of detection (LOD) for benzene vapor is 0.03% by volume in nitrogen, and several chlorinated species had LOD values less than 1%. For binary mixtures of organic vapors, the detected response appears to be the linear combination of the two organic standards, suggesting that the annular column may be useful as a general approach for designing chemical sensors that incorporate separation and optical detection principles simultaneously. PMID:18966560

Bruckner, C A; Synovec, R E

1996-06-01

154

Fiber Optical Micro-detectors for Oxygen Sensing in Power Plants  

Energy Technology Data Exchange (ETDEWEB)

A reflection mode fiber optic oxygen sensor that can operate at high temperatures for power plant applications is being developed. The sensor is based on the {sup 3}O{sub 2} quenching of the red emission from hexanuclear molybdenum chloride clusters. Previously we described a particle-in-binder approach to immobilizing the potassium salt of the molybdenum cluster, K{sub 2}Mo{sub 6}Cl{sub 14}, at the tips of optical fibers. Compared to previous methods, the particle-in-binder approach affords fibers with greatly improved mechanical properties. The response of the sensor to oxygen at 40, 70 and 100 C was measured in 2-21% gas phase oxygen. The normalized sensor signal is linear with molar oxygen concentration and fits the theoretical Stern-Volmer relationship. Although the sensitivity decreases with temperature, at 100 C the sensitivity is 160 [O{sub 2}]{sup -1}. These are promising results for a high temperature fiber optical oxygen sensor based on molybdenum chloride clusters.

Gregory L. Baker; Ruby N. Ghosh; D.J. Osborn III; Po Zhang

2006-05-01

155

Preparation of Tapered Optical Fibers to utilize the Evanescent Field for Sensing Applications  

OpenAIRE

Optical fibers can be tapered in order to utilize the evanescent field present in the cladding region of the fiber. At the beginning of the taper region most of the power is present in the core. In the down taper region the light in the core region couples to the cladding region where the evanescent field is present. In the up taper region, light in the cladding region again couples back into the core region. Our experiment discusses about the process of tapering and the principle of tapered ...

Karra Sony, Soumya M.

2013-01-01

156

Behavior of Random Hole Optical Fibers under Gamma Ray Irradiation and Its Potential Use in Radiation Sensing Applications  

Directory of Open Access Journals (Sweden)

Full Text Available Effects of radiation on sensing and data transmission components are of greatinterest in many applications including homeland security, nuclear power generation, andmilitary. A new type of microstructured optical fiber (MOF called the random hole opticalfiber (RHOF has been recently developed. The RHOFs can be made in many differentforms by varying the core size and the size and extent of porosity in the cladding region.The fibers used in this study possessed an outer diameter of 110 μm and a core ofapproximately 20 μm. The fiber structure contains thousands of air holes surrounding thecore with sizes ranging from less than 100 nm to a few μm. We present the first study ofthe behavior of RHOF under gamma irradiation. We also propose, for the first time to ourknowledge, an ionizing radiation sensor system based on scintillation light from ascintillator phosphor embedded within a holey optical fiber structure. The RHOF radiationresponse was compared to normal single mode and multimode commercial fibers(germanium doped core, pure silica cladding and to those of radiation resistant fibers (puresilica core with fluorine doped cladding fibers. The comparison was done by measuringradiation-induced absorption (RIA in all fiber samples at the 1550 nm wavelength window(1545 ± 25 nm. The study was carried out under a high-intensity gamma ray field from a 60Co source (with an exposure rate of 4x104 rad/hr at an Oak Ridge National Laboratory gamma ray irradiation facility. Linear behavior, at dose values less than 106 rad, was observed in all fiber samples except in the pure silica core fluorine doped cladding fiber which showed RIA saturation at 0.01 dB. RHOF samples demonstrated low RIA (0.02 and 0.005 dB compared to standard germanium doped core pure silica cladding (SMF and MMF fibers. Results also showed the possibility of post-fabrication treatment to improve the radiation resistance of the RHOF fibers.

Anbo Wang

2007-05-01

157

Fiber Optical Micro-detectors for Oxygen Sensing in Power Plants  

Energy Technology Data Exchange (ETDEWEB)

A reflection mode fiber optic oxygen sensor that can operate at high temperatures for power plant applications is being developed. The sensor is based on the {sup 3}O{sub 2} quenching of the red emission from hexanuclear molybdenum chloride clusters. Previously we immobilized the potassium salt of a molybdenum cluster, K{sub 2}M{sub 6}Cl{sub 14}, in a sol-gel matrix and showed that the luminescence is stable after 54 hours at 200 C, but the quenching ratios were low and the films delaminated after thermal cycling due to densification of the matrix. Three new approaches to solve decreased quenching over time and delamination of films off fiber tips were investigated. In the first approach K{sub 2}Mo{sub 6}Cl{sub 14} embedded in cured sol-gel particles were incorporated into a TEOS based sol-gel. These gave enhanced quenching (6x), but delaminated. Our second approach was to use a commercial cyanoacrylate glue to immobilize the particles onto the tip of an optical fiber. This gave better adhesion and good quenching initially, but eventually the glue degraded upon heating. Our third approach was to use a 55% OtMOS/ TEOS sol-gel binder. Films based on this new sol-gel binder show high quenching ({approx}6x) and superior mechanical stability even after thermal cycling. Sensor measurements on an optical fiber containing K{sub 2}Mo{sub 6}Cl{sub 14} embedded in cured sol-gel particles were obtained from 100 to 25 C. The signal intensity in nitrogen was stable at 2.8 {+-} 0.2 nW, and the quenching ratio (ratio of signal in N{sub 2} vs. 21 % O{sub 2}) varied from 4.4 to 6.9X. These are promising results for a high temperature fiber optical oxygen sensor based on molybdenum chloride clusters.

Gregory L. Baker; Ruby N. Ghosh; D.J. Osborn III; Po Zhang

2005-10-01

158

FIBER OPTICAL MICRO-DETECTORS FOR OXYGEN SENSING IN POWER PLANTS  

Energy Technology Data Exchange (ETDEWEB)

A reflection mode fiber optic oxygen sensor that can operate at high temperatures for power plant applications is being developed. The sensor is based on the {sup 3}O{sub 2} quenching of the red emission from hexanuclear molybdenum chloride clusters. One of the critical materials issues is to demonstrate that the luminescent cluster immobilized in the sol-gel porous support can withstand high temperature. At the same time the sol-gel matrix must have a high permeability to oxygen. Using a potassium salt of the molybdenum clusters, K{sub 2}Mo{sub 6}Cl{sub 14}, we have established the conditions necessary for deposition of optical quality sol-gel films. From spectroscopic measurements of the film we have shown that the cluster luminescence is stable following heat cycling of 54 hours at 200 C. Quenching of a factor of 1.5X between pure nitrogen and 21% oxygen was observed from in-situ measurements of films heated directly at 200 C. An automated system for characterizing fiber optic oxygen sensors up to 220 C with a temporal resolution better than 10 s is under construction. We estimate a signal of 6 x 10{sup 8} photons/s after complete quenching in 21% oxygen. These are promising results for a high temperature fiber optical oxygen sensor based on molybdenum chloride clusters.

Gregory L. Baker; Ruby N. Ghosh; D.J. Osborn III; Po Zhang

2005-04-01

159

Fiber optic calorimetry  

International Nuclear Information System (INIS)

A twin-bridge calorimeter using optical fiber as the sensor element was constructed and tested. This system demonstrates the principle and capability of using fiber for heat-flow measurements of special nuclear material. This calorimeter uses piezoelectric-generated phase-carrier modulation with subsequent electronic signal processing to allow phase shifts as small as 1 microradian (?rad) to be measured. The sensing element consists of 21-m lengths of single-mode optical fiber wrapped around sample and reference chambers. The sensitivity of the calorimeter was determined to be 74 radians (rad) of phase shift per milliwatt of thermal power. One milliwatt of thermal power is equivalent to 400 mg of plutonium (6% 240Pu). The system noise base was about 0.2 rad, equivalent to about 1 mg of plutonium

160

Research on corrosion detection for steel reinforced concrete structures using the fiber optical white light interferometer sensing technique  

Science.gov (United States)

In this paper, a novel kind of steel rebar corrosion monitoring technique for steel reinforced concrete structures is proposed, designed, and tested. The technique is based on the fiber optical white light interferometer (WLI) sensing technique. Firstly, a feasibility test was carried out using an equal-strength beam for comparison of strain sensing ability between the WLI and a fiber Bragg grating (FBG). The comparison results showed that the sensitivity of the WLI is sufficient for corrosion expansion strain monitoring. Then, two WLI corrosion sensors (WLI-CSs) were designed, fabricated, and embedded into concrete specimens to monitor expansion strain caused by steel rebar corrosion. Their performance was studied in an accelerated electrochemical corrosion test. Experimental results show that expansion strain along the fiber optical coil winding area can be detected and measured accurately by the proposed sensor. The advantages of the proposed monitoring technique allow for quantitative corrosion expansion monitoring to be executed in real time for reinforced concrete structures and with low cost.

Zhao, Xuefeng; Cui, Yanjun; Wei, Heming; Kong, Xianglong; Zhang, Pinglei; Sun, Changsen

2013-06-01

161

Research on corrosion detection for steel reinforced concrete structures using the fiber optical white light interferometer sensing technique  

International Nuclear Information System (INIS)

In this paper, a novel kind of steel rebar corrosion monitoring technique for steel reinforced concrete structures is proposed, designed, and tested. The technique is based on the fiber optical white light interferometer (WLI) sensing technique. Firstly, a feasibility test was carried out using an equal-strength beam for comparison of strain sensing ability between the WLI and a fiber Bragg grating (FBG). The comparison results showed that the sensitivity of the WLI is sufficient for corrosion expansion strain monitoring. Then, two WLI corrosion sensors (WLI-CSs) were designed, fabricated, and embedded into concrete specimens to monitor expansion strain caused by steel rebar corrosion. Their performance was studied in an accelerated electrochemical corrosion test. Experimental results show that expansion strain along the fiber optical coil winding area can be detected and measured accurately by the proposed sensor. The advantages of the proposed monitoring technique allow for quantitative corrosion expansion monitoring to be executed in real time for reinforced concrete structures and with low cost. (paper)

162

Functionalized bioinspired microstructured optical fiber pores for applications in chemical vapor sensing  

Science.gov (United States)

Chemical vapor sensing for defense, homeland security, environmental, and agricultural application is a challenge, which due combined requirements of ppt sensitivity, high selectivity, and rapid response, cannot be met using conventional analytical chemistry techniques. New sensing approaches and platforms are necessary in order to make progress in this rapidly evolving field. Inspired by the functionalized nanopores on moth sensilla hairs that contribute to the high selectivity and sensitivity of this biological system, a chemical vapor sensor based on the micro to nanoscale pores in microstructured optical fibers (MOFs) was designed. This MOF based chemical vapor sensor design utilizes MOF pores functionalized with organic self-assembled monolayers (SAMs) for selectivity and separations and a gold plasmonic sensor for detection and discrimination. Thin well-controlled gold films in MOF pores are critical components for the fabrication of structured plasmonic chemical vapor sensors. Thermal decomposition of dimethyl Au(II) trifluoroacetylacetonate dissolved in near-critical CO2 was used to deposit gold island films within the MOF pores. Using a 3mercatopropyltrimethoxysilane adhesion layer, continuous gold thin films as thin as 20--30 nm were deposited within MOF pores as small as 500 nm in diameter. The gold island films proved to be SERS active and were used to detect 900 ppt 2,4 DNT vapor in high pressure nitrogen and 6 ppm benzaldehyde. MOF based waveguide Raman (WGR), which can probe the air/silica interface between a waveguiding core and surrounding pores, was developed to detect and characterize SAMs and other thin films deposited in micro to nanoscale MOF pores. MOF based WGR was used to characterize an octadecyltrichlorosilane (OTS) SAM deposited in 1.6 mum diameter pores iv to demonstrate that the SAM was well-formed, uniform along the pore length, and only a single layer. MOF based WGR was used to detect a human serum albumin monolayer deposited on the OTS SAM and monitor in-situ the combustion of an OTS SAM in high pressure oxygen. Light scattering, an optical characterization technique that provides ellipsometric data from micro to nanoscale cylinders, was developed in order to characterize highly smooth wires and MOF pores. Clean, bare gold wires etched from MOF pore templates were found to have angle dependent Psi and Delta values that agree with numerically calculated and finite element modeled values over the full angular 340° collection range. Light scattering was shown to be sensitive to ellipticities in the cross-section of silica, gold, and silicon wires down to 1%. Using alkanethiol SAMs deposited on gold wires, light scattering was demonstrated to be able to detect films as thin as 1.5 nm, and able to distinguish between a decanethiol (1.5 nm) and an octadecanethiol SAM (2.7 mn). The high sensitivity of light scattering will allow it to characterize SAMs and thin films on the inner surfaces of MOF pores. WGR and light scattering provide the analytical tools that will allow for the further development of organic SAMs and thin films within MOF pores for analyte selectivity and chromatographic separations. This high selectivity combined with the sensitivity of a 3-dimensional nanostructured gold plasmonic sensor allows for the fabrication of a chemical vapor sensor inspired by the field performance of moth sensilla hairs.

Calkins, Jacob A.

163

Remote optical sensing on the nanometer scale with a bowtie aperture nano-antenna on a SNOM fiber tip  

CERN Document Server

Plasmonic nano-antennas have proven the outstanding ability of sensing chemical and physical processes down to the nano-meter scale. Sensing is usually achieved within the highly confined optical fields generated resonantly by the nano-antennas, i.e. in contact to the nano-structures. In these paper, We demonstrate the sensing capability of nano-antennas to their larger scale environment, well beyond their plasmonic confinement volume, leading to the concept of 'remote' (non contact) sensing on the nano-meter scale. On the basis of a bowtie-aperture nano-antenna (BNA) integrated at the apex of a SNOM fiber tip, we introduce an ultra-compact, move-able and background-free optical nano-sensor for the remote sensing of a silicon surface (up to distance of 300 nm). Sensitivity of the BNA to its large scale environment is high enough to expect the monitoring and control of the spacing between the nano-antenna and a silicon surface with sub-nano-meter accuracy. This work paves the way towards a new class of nano-po...

Atie, Elie M; Eter, Ali El; Salut, Roland; Nedeljkovic, Dusan; Tannous, Tony; Baida, Fadi I; Grosjean, Thierry

2015-01-01

164

Optical fibre sensing of plasmas  

International Nuclear Information System (INIS)

The progress of optical fiber technology for communications has induced an interest in, among others, the sensing of a wide range of physical, and chemical quantities. Any application of optical fibers that are crucial for communication are significant for sensing, e.g. small dimension, insulating materials, immunity to high voltage field etc. In the present paper basic points of optical fiber sensing are summarized. It is noted optical fiber sensors come in two forms, intrinsic and extrinsic. In the former the fiber itself works as sensing element, in addition to data transmission lines. In an intrinsic sensor, a single fiber transmits the light from the source to the detector and the light is modulated while it is in the fiber. On the other hand, in the extrinsic sensor, the light leaves the input fiber to be modulated before being collected by the second output fiber. Characteristic of the light that can be modulated are amplitude, phase, polarization, and wavelength. The paper describes the modulation in some details. (author)

165

300 m optic fiber Bragg grating temperature sensing system for seawater measurement  

International Nuclear Information System (INIS)

Optic fiber grating sensor is a research hotspot.It has been used on many occasions,and how to use it for ocean detection is a new research directions. The paper introduced the calibration work of FBG temperature sensors. It confirmed that from being armored package,the sensors can eliminate the water pressure effect. From the calibration experiment and data processing,60 sensors has little error were screened out for experiment. 300 m long optic fiber Bragg grating sensor array was designed.The marine experiments were achived in South China Sea with 300 meters long Bragg grating array and got the seawater profile temperature. Proposed the curve fitting method to process the data based on Levenberg-Marquardt algorithm. By curve fitting to the data acquired,the precision was better than 0.2 deg. C, which verified the effectiveness of the method.This result has practical value.

166

300 m optic fiber Bragg grating temperature sensing system for seawater measurement  

Energy Technology Data Exchange (ETDEWEB)

Optic fiber grating sensor is a research hotspot.It has been used on many occasions,and how to use it for ocean detection is a new research directions. The paper introduced the calibration work of FBG temperature sensors. It confirmed that from being armored package,the sensors can eliminate the water pressure effect. From the calibration experiment and data processing,60 sensors has little error were screened out for experiment. 300 m long optic fiber Bragg grating sensor array was designed.The marine experiments were achived in South China Sea with 300 meters long Bragg grating array and got the seawater profile temperature. Proposed the curve fitting method to process the data based on Levenberg-Marquardt algorithm. By curve fitting to the data acquired,the precision was better than 0.2 deg. C, which verified the effectiveness of the method.This result has practical value.

Li Xingrong; Li Yongqian; Wen Zhengyang, E-mail: li_xingrong@yahoo.cn [Department of Electronics and Communication Engineering, North China Electric Power University, Baoding 071003 (China)

2011-02-01

167

Survey of fiber-optic sensor for remote sensing in radiologically and chemically harsh environments  

International Nuclear Information System (INIS)

The need for suitable remote sensors in highly radioactive defense waste storage tanks is discussed. The harsh radiological and chemical tank environment precludes the use of standard sensors because of the need for intrinsically safe systems. Potential sensor systems based on fiber-optics technologies suitable for hardening to the tank environment are identified. The need for certification standards for this type of environment is also discussed

168

Current sensing in magnetic fusion experiments by Faraday rotation in single-mode optical fibers  

International Nuclear Information System (INIS)

We find that sensors exploiting the Faraday effect in single-mode optical fibers are practical means of measuring large currents in the MFE environment. Work still needs to be done to overcome the effects of linear birefringence. We have seen distortion caused by dynamic stress-induced birefringence and shown the importance of physically eliminating it because of the difficulty of treating it analytically

169

Current sensing in magnetic fusion experiments by Faraday rotation in single-mode optical fibers  

Energy Technology Data Exchange (ETDEWEB)

We find that sensors exploiting the Faraday effect in single-mode optical fibers are practical means of measuring large currents in the MFE environment. Work still needs to be done to overcome the effects of linear birefringence. We have seen distortion caused by dynamic stress-induced birefringence and shown the importance of physically eliminating it because of the difficulty of treating it analytically.

Chandler, G.I.; Jahoda, F.C.

1983-01-01

170

Fiber Optic Sensors and Sensor Networks Using a Time-domain Sensing Scheme  

Directory of Open Access Journals (Sweden)

Full Text Available Fiber loop ringdown (FLRD has demonstrated to be capable of sensing various quantities, such as chemical species, pressure, refractive index, strain, temperature, etc.; and it has high potential for the development of a sensor network. In the present work, we describe design and development of three different types of FLRD sensors for water, cracks, and temperature sensing in concrete structures. All of the three aforementioned sensors were indigenously developed very recently in our laboratory and their capabilities of detecting the respective quantities were demonstrated. Later, all of the sensors were installed in a test grout cube for real-time monitoring. This work presents the results obtained in the laboratory-based experiments as well as the results from the real-time monitoring process in the test cube.

Chuji Wang

2013-06-01

171

An air flow sensor for neonatal mechanical ventilation applications based on a novel fiber-optic sensing technique  

International Nuclear Information System (INIS)

In this work, a simple and low-cost air flow sensor, based on a novel fiber-optic sensing technique has been developed for monitoring air flows rates supplied by a neonatal ventilator to support infants in intensive care units. The device is based on a fiber optic sensing technique allowing (a) the immunity to light intensity variations independent by measurand and (b) the reduction of typical shortcomings affecting all biomedical fields (electromagnetic interference and patient electrical safety). The sensing principle is based on the measurement of transversal displacement of an emitting fiber-optic cantilever due to action of air flow acting on it; the fiber tip displacement is measured by means of a photodiode linear array, placed in front of the entrance face of the emitting optical fiber in order to detect its light intensity profile. As the measurement system is based on a detection of the illumination pattern, and not on an intensity modulation technique, it results less sensitive to light intensity fluctuation independent by measurand than intensity-based sensors. The considered technique is here adopted in order to develop two different configurations for an air flow sensor suitable for the measurement of air flow rates typically occurring during mechanical ventilation of newborns: a mono-directional and a bi-directional transducer have been proposed. A mathematical model for the air flow sensor is here proposed and a static calibration of two different arraa static calibration of two different arrangements has been performed: a measurement range up to 3.00 × 10?4 m3/s (18.0 l/min) for the mono-directional sensor and a measurement range of ±3.00 × 10?4 m3/s (±18.0 l/min) for the bi-directional sensor are experimentally evaluated, according to the air flow rates normally encountered during tidal breathing of infants with a mass lower than 10 kg. Experimental data of static calibration result in accordance with the proposed theoretical model: for the mono-directional configuration, the coefficient of determination r2 is equal to 0.997; for the bi-directional configuration, the coefficient of determination r2 is equal to 0.990 for positive flows (inspiration) and 0.988 for negative flows (expiration). Measurement uncertainty ?Q of air flow rate has been evaluated by means of the propagation of distributions and the percentage error in the arrangement of bi-directional sensor ranges from a minimum of about 0.5% at ?18.0 l/min to a maximum of about 9% at ?12.0 l/min.

172

Sensing parts per million levels of gaseous NO2 by a optical fiber transducer based on calix[4]arenes.  

Science.gov (United States)

Calixarenes are interesting building blocks in supramolecular receptor design. They can be easily functionalized to give the desired guest binding and sequestration properties. We demonstrate here the use of simple alkylated calixarenes as novel NO(2) sensors. Upon reacting with gaseous NO(2), alkylated calixarenes form stable calixarene-NO(+) (nitrosonium) complexes that have a deep purple color. This specific and selective formation of the colored complex was used to develop a fiber optic based colorimetric NO(2) sensor. Several alkylated calixarenes are used and tested as sensing materials. The calixarene compound was immobilized on a fine mesh silica-gel coated thin layer chromatography plate. The sensing plate was coupled with a fiber optic based photodetector. Gas samples were sampled in a manner where they impinged on the surface of sensing plate. The light transmission through the plate was continuously monitored. For a 5 min sample, the limit of detection was 0.54 ppmv with 1,3-alternate O-hexyl calix[4]arene (1a). There were no significant response differences between different conformations of calixarenes such as 1,3-alternate or cone. This chemistry can form the basis of a colorimetric sensor that relies on extant filter tape technology. With calixarenes however, such a reaction is potentially reversible - color formed upon reaction with NO(2) can be reversed by flushing the sensing plate by purified air. While we found that the removal of the developed color can be accelerated by simultaneous heating and suction, permitting the reuse of the same sensing area multiple times, we also observed that the sensitivity gradually decreased. The nitrosonium calixarene derivative tends to transform to the nitrated form; this process is catalyzed by light. Several methylated calixarenes were synthesized and tested but a fully satisfactory solution has proven elusive. PMID:19159804

Ohira, Shin-Ichi; Wanigasekara, Eranda; Rudkevich, Dmitry M; Dasgupta, Purnendu K

2009-03-15

173

Optical fiber distributed sensing structural health monitoring (SHM) strain measurements taken during cryotank Y-joint test article load cycling at liquid helium temperatures  

Science.gov (United States)

This paper outlines cryogenic Y-joint testing at Langley Research Center (LaRC) to validate the performance of optical fiber Bragg grating strain sensors for measuring strain at liquid helium temperature (-240°C). This testing also verified survivability of fiber sensors after experiencing 10 thermal cool-down, warm-up cycles and 400 limit load cycles. Graphite composite skins bonded to a honeycomb substrate in a sandwich configuration comprised the Y-joint specimens. To enable SHM of composite cryotanks for consideration to future spacecraft, a light-weight, durable monitoring technology is needed. The fiber optic distributed Bragg grating strain sensing system developed at LaRC is a viable substitute for conventional strain gauges which are not practical for SHM. This distributed sensing technology uses an Optical Frequency Domain Reflectometer (OFDR). This measurement approach has the advantage that it can measure hundreds of Bragg grating sensors per fiber and the sensors are all written at one frequency, greatly simplifying fiber manufacturing. Fiber optic strain measurements compared well to conventional strain gauge measurements obtained during these tests. These results demonstrated a high potential for a successful implementation of a SHM system incorporating LaRC's fiber optic sensing system on the composite cryotank and other future cryogenic applications.

Allison, Sidney G.; Prosser, William H.; Hare, David A.; Moore, Thomas C.; Kenner, W. S.

2007-09-01

174

Optical Fiber Distributed Sensing Structural Health Monitoring (SHM) Strain Measurements Taken During Cryotank Y-Joint Test Article Load Cycling at Liquid Helium Temperatures  

Science.gov (United States)

This paper outlines cryogenic Y-joint testing at Langley Research Center (LaRC) to validate the performance of optical fiber Bragg grating strain sensors for measuring strain at liquid helium temperature (-240 C). This testing also verified survivability of fiber sensors after experiencing 10 thermal cool-down, warm-up cycles and 400 limit load cycles. Graphite composite skins bonded to a honeycomb substrate in a sandwich configuration comprised the Y-joint specimens. To enable SHM of composite cryotanks for consideration to future spacecraft, a light-weight, durable monitoring technology is needed. The fiber optic distributed Bragg grating strain sensing system developed at LaRC is a viable substitute for conventional strain gauges which are not practical for SHM. This distributed sensing technology uses an Optical Frequency Domain Reflectometer (OFDR). This measurement approach has the advantage that it can measure hundreds of Bragg grating sensors per fiber and the sensors are all written at one frequency, greatly simplifying fiber manufacturing. Fiber optic strain measurements compared well to conventional strain gauge measurements obtained during these tests. These results demonstrated a high potential for a successful implementation of a SHM system incorporating LaRC's fiber optic sensing system on the composite cryotank and other future cryogenic applications.

Allison, Sidney G.; Prosser, William H.; Hare, David A.; Moore, Thomas C.; Kenner, Winfred S.

2007-01-01

175

Evaluation of temperature distribution sensing method for fast reactor using optical fiber  

Energy Technology Data Exchange (ETDEWEB)

Optical fiber sensors (OFSs) have many advantages like flexible configuration, intrinsic immunity for electromagnetic fields, and so on. For these reasons, it is very useful to apply OFSs to fast reactor plants for remote inspection and surveillance. However, under irradiation, because of radiation-induced transmission loss of optical fibers, OFSs have radiation-induced errors. Therefore, to apply OFSs to nuclear facilities, we have to estimate and correct the errors. In this report, Raman Distributed Temperature Sensor (RDTS; one of the OFSs) has been installed at the primary coolant loop of the experimental fast reactor JOYO of JNC (Japan Nuclear Cycle Development Institute). Two correction techniques (correction technique with two thermocouples and correction technique with loop arrangement) for radiation-induced errors have been developed and demonstrated. Because of the radiation-induced loss, measured temperature distributions had radiation-induced errors. However, during the continuous measurements with the total dose of more than 8 x 10{sup 3}[C/kg](3 x 10{sup 7}[R]), the radiation induced errors showed a saturation tendency. In case of the temperature distributions with fluorine doped fiber, with one of the correction techniques, the temperature errors reduced to 1{approx}2degC and the feasibility of the loss correction techniques was demonstrated. For these results, it can be said that RDTS can be applied as a temperature distribution monitor in harsh radiation environments like fast reactor plants. (author)

Kimura, Atsushi; Nakazawa, Masaharu [Tokyo Univ. (Japan); Ichige, Satoshi [Japan Nuclear Cycle Development Inst., Oarai, Ibaraki (Japan). Oarai Engineering Center

1999-12-01

176

Evaluation of temperature distribution sensing method for fast reactor using optical fiber  

International Nuclear Information System (INIS)

Optical fiber sensors (OFSs) have many advantages like flexible configuration, intrinsic immunity for electromagnetic fields, and so on. For these reasons, it is very useful to apply OFSs to fast reactor plants for remote inspection and surveillance. However, under irradiation, because of radiation-induced transmission loss of optical fibers, OFSs have radiation-induced errors. Therefore, to apply OFSs to nuclear facilities, we have to estimate and correct the errors. In this report, Raman Distributed Temperature Sensor (RDTS; one of the OFSs) has been installed at the primary coolant loop of the experimental fast reactor JOYO of JNC (Japan Nuclear Cycle Development Institute). Two correction techniques (correction technique with two thermocouples and correction technique with loop arrangement) for radiation-induced errors have been developed and demonstrated. Because of the radiation-induced loss, measured temperature distributions had radiation-induced errors. However, during the continuous measurements with the total dose of more than 8 x 103[C/kg](3 x 107[R]), the radiation induced errors showed a saturation tendency. In case of the temperature distributions with fluorine doped fiber, with one of the correction techniques, the temperature errors reduced to 1?2degC and the feasibility of the loss correction techniques was demonstrated. For these results, it can be said that RDTS can be applied as a temperature distribution monitor in harsh radiation environments like fast reactor plants. (author)

177

Multichannel optical sensing device  

Science.gov (United States)

A multichannel optical sensing device is disclosed, for measuring the outr sky luminance or illuminance or the luminance or illuminance distribution in a room, comprising a plurality of light receptors, an optical shutter matrix including a plurality of liquid crystal optical shutter elements operable by electrical control signals between light transmitting and light stopping conditions, fiber optic elements connected between the receptors and the shutter elements, a microprocessor based programmable control unit for selectively supplying control signals to the optical shutter elements in a programmable sequence, a photodetector including an optical integrating spherical chamber having an input port for receiving the light from the shutter matrix and at least one detector element in the spherical chamber for producing output signals corresponding to the light, and output units for utilizing the output signals including a storage unit having a control connection to the microprocessor based programmable control unit for storing the output signals under the sequence control of the programmable control unit.

Selkowitz, Stephen E. (Piedmont, CA)

1990-01-01

178

Wide-area remote-sensing system of pollution and gas dispersal by near-infrared absorption based on low-loss optical fiber network  

Science.gov (United States)

An all optical remote sensing system utilizing long distance, ultralow loss optical fiber networks is studied and discussed for near infrared absorption measurements of combustible and/or explosive gases such as CH4 and C3H8 in our environment, including experimental results achieved in a diameter more than 20 km. The use of a near infrared wavelength range is emphasized.

Inaba, H.

1986-01-01

179

Use of the polarization properties of magneto-optic fiber Bragg gratings for magnetic field sensing purposes  

Science.gov (United States)

The transmission and polarization properties of magneto-optic fiber Bragg gratings (MFBGs) with Faraday Effect are studied in this paper. The evolutions of transmission spectrum for different input state of polarizations (SOPs) are simulated with Jones Matrix method. It is demonstrated that the monitoring of the polarization-dependent loss (PDL) maximum values provide a new magnetic field measurement. Furthermore the influences of transmission spectrum on the characteristics of MFBG sensors are analyzed. It is shown that the sensitivity and measurement range depend on the slope and bandwidth of the transmission spectrum, respectively. Moreover the MFBG structure with triangular-shaped transmission spectrum is designed for dynamic magnetic field sensing. The simulation shows that the maximal amplitude of the PDL varies linearly in the magnetic field range of 0-114.2 mT with a slope of 0.091 dB/mT. A multi-section MFBG structure is also proposed for distributed magnetic field sensing.

Su, Yang; Zhu, Yong; Zhang, Baofu; Li, Jianhua; Li, Yuquan

2011-05-01

180

FIBER OPTICAL MICRO-DETECTORS FOR OXYGEN SENSING IN POWER PLANTS  

Energy Technology Data Exchange (ETDEWEB)

A reflection mode fiber optic oxygen sensor that can operate at high temperatures for power plant applications is being developed. The sensor is based on the {sup 3}O{sub 2} quenching of the red emission from hexanuclear molybdenum chloride clusters. One of the critical materials issues is to demonstrate that the luminescent cluster immobilized in the sol-gel porous support can withstand high temperature. At the same time the sol-gel matrix must have a high permeability to oxygen. Using a potassium salt of the molybdenum clusters, K{sub 2}Mo{sub 6}Cl{sub 14}, we have established the conditions necessary for deposition of optical quality sol-gel films. From spectroscopic measurements of the film we have shown that the cluster luminescence is stable following heat cycling of 1 hour at 250 C. Quenching of a factor of 4X between pure nitrogen and 21% oxygen was observed for films cured directly at 200 C. These are promising results for a high temperature fiber optical oxygen sensor based on molybdenum chloride clusters.

Gregory L. Baker; Ruby N. Ghosh; D.J. Osborn III; Po Zhang

2005-01-01

181

Fiber optic strain, temperature and shape sensing via OFDR for ground, air and space applications  

Science.gov (United States)

Optical Frequency Domain Reflectometry (OFDR) is used to interrogate fiber sensors adhered to various structures. Temperatures in excess of 1000°C are observed on a thermal-barrier coated stainless steel test plate as it is exposed to a high-temperature torch. The surface temperature distribution is mapped with 5 mm spatial resolution at 100 Hz, revealing large spatial and temporal thermal gradients at coating defect locations. Results and response times are compared with conventional K type thermocouples. Also presented in this work, are real-time position, shape and twist measurements of a simple structure as it is subjected to various loads.

Bos, Joseph; Klein, Justin; Froggatt, Mark; Sanborn, Eric; Gifford, Dawn

2013-09-01

182

Optimization of wideband fiber optic hydrophone probe for ultrasound sensing applications  

Science.gov (United States)

Acoustic characterization of medical ultrasound devices is needed for optimization of image quality in diagnostic applications and to ensure their safety and effectiveness in therapeutic applications. New generation of acoustic transducers operating at fundamental frequency 15 MHz are being developed and FDA requires that as many as 8 harmonics are considered for real-time pressure-time waveform measurements in dispersive nonlinear medium. Therefore, hydrophone probes are required to perform characterization of the acoustic output of these devices at least up to 100 MHz in terms of frequency response. The primary goal of this thesis is to develop a Fiber Optic Hydrophone Probe (FOHP) for spatial averaging free characterization of ultrasound field till 100 MHz. Spatial averaging free design of the sensor is based on optimization of fiber geometry to achieve an active fiber dimension of the order of 7 mum to be comparable with half of the acoustic wavelength at 100 MHz. An innovative aspect of this work includes the development of a semi-empirical model for extraction of complex refractive index at optical wavelengths of 980 nm, 1480 nm and 1550 nm and stress-strain relationship of thin film gold for thickness ranging from 2nm--35nm. These are indispensable in modeling and optimization of 100 MHz FOHP in calculation of optimized pressure to voltage responsivity. For responsivity optimization, a novel multi-physics numerical model based on the Finite Element Method (FEM) was employed to solve electromagnetic, mechanics, and acoustics performance of the FOHP. The model and the selection of its input parameters, including coupled acousto-optic interaction of thin film gold, are based on published physical parameters and accurate extraction of various fiber parameters. Optimization results indicate that cylindrically etched FOHP with 6 mum tip diameter and 5 nm gold coating provides the highest responsivity performance of 234 dB re 1V/ muPa. The experimental verification of the thin film coated FOHP using 1 MPa pressure amplitude, produced unprecedented voltage responsivity between -234 and -254 dB re 1V/muPa or 2V/MPa and 200 mV/MPa, respectively. The optimum detection sensitivity of around 0.3 kPa is achieved by Relative Intensity Noise cancellation of 10 dB using balanced optical photo-detector.

Minasamudram, Rupa Gopinath

183

Application of Fiber Optic Instrumentation  

Science.gov (United States)

Fiber optic sensing technology has emerged in recent years offering tremendous advantages over conventional aircraft instrumentation systems. The advantages of fiber optic sensors over their conventional counterparts are well established; they are lighter, smaller, and can provide enormous numbers of measurements at a fraction of the total sensor weight. After a brief overview of conventional and fiber-optic sensing technology, this paper presents an overview of the research that has been conducted at NASA Dryden Flight Research Center in recent years to advance this promising new technology. Research and development areas include system and algorithm development, sensor characterization and attachment, and real-time experimentally-derived parameter monitoring for ground- and flight-based applications. The vision of fiber optic smart structure technology is presented and its potential benefits to aerospace vehicles throughout the lifecycle, from preliminary design to final retirement, are presented.

Richards, William Lance; Parker, Allen R., Jr.; Ko, William L.; Piazza, Anthony; Chan, Patrick

2012-01-01

184

Lamb wave-based damage detection of composite shells using high-speed fiber-optic sensing  

Science.gov (United States)

A Lamb wave-based damage identification method called damage imaging method for composite shells is presented. A damage index (DI) is generated from the delay matrix of the Lamb wave response signals, and it is used to indicate the location and approximate area of the damage. A piezoelectric actuator is employed to generate the Lamb waves that are subsequently captured by a fiber Bragg grating (FBG) sensor element array multiplexed in a single fiber connected to a high-speed fiber-optic sensor system. The high-speed sensing is enabled by an innovative parallel-architecture optical interrogation system. The viability of this method is demonstrated by analyzing the numerical and experimental Lamb wave response signals from laminated composite shells. The technique only requires the response signals from the plate after damage, and it is capable of performing near real-time damage identification. This study sheds some light on the application of a Lamb wave-based damage detection algorithm for curved plate/shell-type structures by using the relatively low frequency (around 100 kHz) Lamb wave response and the high-speed FBG sensor system.

Sotoudeh, Vahid; Black, Richard J.; Moslehi, Behzad; Qiao, Pizhong

2014-04-01

185

Microstructured optical fiber Bragg grating-based strain and temperature sensing in the concrete buffer of the Belgian supercontainer concept  

Science.gov (United States)

We present the use of microstructured optical fiber Bragg grating-based sensors for strain and temperature monitoring inside the concrete buffer of the Belgian supercontainer concept, demonstrated in a half-scale test in 2013. This test incorporated several optical fiber sensors inside the concrete buffer for production and condition monitoring. The optical fiber sensors presented here consist of small carbon-reinforced composite plates in which highly birefringent Butterfly microstructured optical fibers, equipped with fiber Bragg gratings, were embedded. The double reflection spectrum of these MOFGBs allows to simultaneously monitor strain and temperature, as confirmed by comparison with data obtained from thermocouples and vibrating-wire sensors installed near the MOFBGs.

Geernaert, Thomas; Sulejmani, Sanne; Sonnenfeld, Camille; Luyckx, Geert; Chah, Karima; Areias, Lou; Mergo, Pawel; Urbanczyk, Waclaw; Van Marcke, Philippe; Coppens, Erik; Thienpont, Hugo; Berghmans, Francis

2014-05-01

186

Fiber Singular Optics  

Directory of Open Access Journals (Sweden)

Full Text Available The present review is devoted to the optical vortex behavior both in free space and optical fibers. The processes of the vortex transformations in perturbed optical fibers are analyzed on the base of the operator of the spin – orbit interaction in order to forecast the possible ways of manufacturing the vortex preserving fibers and their applications in supersensitive optical devices.

A. V. Volyar

2002-06-01

187

Fiber optic Brillouin distributed sensing using phase-shift keying modulation techniques  

Science.gov (United States)

In this work we demonstrate two new BOTDA sensing systems based on differential (DPSK) and quadrature (QPSK) phase-shift keying modulation techniques with enhanced performances. First we demonstrate Brillouin echoes distributed sensing (BEDS) with centimeter resolution using a single intensity DPSK modulator for the pump pulse. The optical ?-phase pulse is directly generated at the end of an intensity pulse using DPSK technique. This allows an easy adjustment of the delay between the intensity and phase pulse and improves the optical loss of the pump. The second technique uses an optical QPSK modulator (I & Q modulator) as a single sideband (SSB) modulator. The advantage of I & Q modulator compared to dual-drive modulator lies on the high performance of carrier suppression of 55 dB as well as side-mode suppression of 40 dB at 1535 nm. Besides the filter that chooses either the Stokes or anti-Stokes component before detecting the Brillouin response on the photodiode is no more needed. By use of the I & Q modulator the performance of BOTDA using either Stokes or anti-Stokes component is shown and discussed.

Stiller, Birgit; Lee, Min W.; Nguyen, Duc Minh; Hauden, Jerôme; Mottet, Alexandre; Maillotte, Hervé; Sylvestre, Thibaut

2012-04-01

188

Photonic crystal sensing of components of a liquid mixture using an optical fiber spectrometer  

Science.gov (United States)

We report the application of a photonic crystal sensor for the components of a liquid mixture by a simple and easy technique. A closely packed colloidal crystal film is made of arrayed 202-nm PS particles and PDMS elastomer is used for filling the voids in the film. Bragg's diffraction in the visible wavelength region causes the formation of a structural color in the colloidal crystal. The structural color varies according to the solvents depending on the swelling ability of the PDMS elastomer. We can perform the quantitative analysis of the swelling phenomena by measuring Bragg's diffraction peaks. The peak shifts as a function of the mixing ratio of the solvents, i.e., methanol, ethanol, and propanol. The peak position is proportional to the solvent concentration. In the case of a water-ethanol system, there is little peak-shift up to 80 vol.% of ethanol concentration. Above this concentration, the rate of peak shift increases beyond 50 nm. A reflectance spectrometer enables the detection of the components of ethanol liquids with the volume concentration of water ranging from 0 to 10%. In this study, a commercially available optical fiber spectrometer detects the volume concentrations of water of the order of 1 vol.% in ethanol. The photonic sensor has the potential to be used in a rapid analysis method that employs a portable optical fiber spectrometer.

Fudouzi, Hiroshi; Sawada, Tsutomu

2007-09-01

189

The modification methods of polymer fiber cladding for sensing application  

Science.gov (United States)

Optical fibers have been used in numerous sensing applications. Specifically, polymer-clad silica optical fibers have been employed for purposes of indirect chemical or biochemical sensors. These sensors are based on the interaction of guided light beams with extrinsic reagents immobilized in the fiber cladding. For this demand, it is necessary to enrich the fiber cladding with optical reagents with suitable optical properties without mechanical damage of cladding. Dipcoating and diffusion process have been studied and compared with respect to effective incorporation of appropriate quantities of selected organic reagents into polymer cladding. Short sections of sensitized optical fibers have been tested for potential using in ammonia fiber optic sensors.

Aubrecht, Jan; Kalvoda, Ladislav; Levinský, Petr; Fojtíková, Jaroslava

2015-01-01

190

Fiber Optics Instrumentation Development  

Science.gov (United States)

This is a general presentation of fiber optics instrumentation development work being conducted at NASA Dryden for the past 10 years and recent achievements in the field of fiber optics strain sensors.

Chan, Patrick Hon Man; Parker, Allen R., Jr.; Richards, W. Lance

2010-01-01

191

Fiber optic sensing of relative humidity using a twin low coherence interferometer  

Scientific Electronic Library Online (English)

Full Text Available SciELO Mexico | Language: English Abstract in spanish En este trabajo se describe un sensor de humedad de fibra óptica que consiste en dos interferómetros de Sagnac con secciones de fibra óptica torcida de alta birrefringencia. Las fibras birrefringentes sirven como elementos sensibles a la temperatura que permiten medir simultáneamente la temperatura [...] de bulbo seco y bulbo mojado. Se describe el método para interrogación de dos sensores de temperatura basados en la interferometría de baja coherencia con procesamiento de señales en el dominio espectral. La incertidumbre de la medición, estimada experimentalmente, es de 0.01°C y 4% para mediciones de temperatura y humedad, respectivamente. Abstract in english A fiber-optic implementation of psychrometer is reported. It consists of two Sagnac interferometers with twisted highly birefringent fiber that is used as a temperature sensitive element. One interferometer is used for dry-bulb temperature measurement and the other is for wet-bulb temperature monito [...] ring. The interrogation technique for low coherence interferometric sensor with signal processing in spectral domain is described. The measurement uncertainties for temperature and relative humidity measurements no worse than 0.01°C and 4%, respectively, have been achieved experimentally.

A.V., Khomenko; J., Tapia-Mercado; M.A., García-Zarate.

2010-06-01

192

Monitoring of Thermal Protection Systems Using Robust Self-Organizing Optical Fiber Sensing Networks  

Science.gov (United States)

The general aim of this work is to develop and demonstrate a prototype structural health monitoring system for thermal protection systems that incorporates piezoelectric acoustic emission (AE) sensors to detect the occurrence and location of damaging impacts, and an optical fiber Bragg grating (FBG) sensor network to evaluate the effect of detected damage on the thermal conductivity of the TPS material. Following detection of an impact, the TPS would be exposed to a heat source, possibly the sun, and the temperature distribution on the inner surface in the vicinity of the impact measured by the FBG network. A similar procedure could also be carried out as a screening test immediately prior to re-entry. The implications of any detected anomalies in the measured temperature distribution will be evaluated for their significance in relation to the performance of the TPS during re-entry. Such a robust TPS health monitoring system would ensure overall crew safety throughout the mission, especially during reentry

Richards, Lance

2013-01-01

193

Sapphire ball lensed fiber probe for common-path optical coherence tomography in ocular imaging and sensing  

Science.gov (United States)

We describe a novel common-path optical coherence tomography (CP-OCT) fiber probe design using a sapphire ball lens for cross-sectional imaging and sensing in retina vitrectomy surgery. Single mode Gaussian beam (TEM00) simulation was used to optimize lateral resolution and working distance (WD) of the common-path probe. A theoretical sensitivity model for CP-OCT was prosed to assess its optimal performance based an unbalanced photodetector configuration. Two probe designs with working distances (WD) 415?m and 1221?m and lateral resolution 11?m and 18?m, respectively were implemented with sensitivity up to 88dB. The designs are also fully compatible with conventional Michelson interferometer based OCT configurations. The reference plane of the probe, located at the distal beam exit interface of the single mode fiber (SMF), was encased within a 25-gauge hypodermic needle by the sapphire ball lens facilitates its applications in bloody and harsh environments. The performances of the fiber probe with 11?m of lateral resolution and 19?m of axial resolution were demonstrated by cross-sectional imaging of a cow cornea and retina in vitro with a 1310nm swept source OCT system. This probe was also attached to a piezoelectric motor for active compensation of physiological tremor for handheld retinal surgical tools.

Zhao, Mingtao; Huang, Yong; Kang, Jin U.

2013-03-01

194

Application of optical fiber distributed sensing to health monitoring of concrete structures  

Science.gov (United States)

The use of Optical Backscatter Reflectometer (OBR) sensors is a promising measurement technology for Structural Health Monitoring (SHM) as it offers the possibility of continuous monitoring of strain and temperature along the fiber. Several applications to materials used in the aeronautical construction have demonstrated the feasibility of such technique. These materials (composites, steel, aluminum) apart from having a smooth surface where the bonding of the sensor is easily carried out, they also have a continuous strain field when subject to external loading and therefore the bonding of the OBR on the material surface is not in danger for high levels of loading as the OBR can easily follow the strain in the material. The application of such type of sensor to concrete structures may present some difficulties due to (1) the roughness of the concrete surface and the heterogeneity due to the presence of aggregates of several sizes, (2) the fact that reinforced concrete cracks at very low level of load, appearance of a discontinuity in the surface and the strain field that may provoke a break or debonding of the optical fiber. However the feasibility of using OBR in the SHM of civil engineering constructions made of concrete is also of great interest, mainly because in this type of structures it is impossible to know where the crack may appear and therefore severe cracking (dangerous for the structure operation) can appear without warning of the monitoring if sensors are not placed in the particular location where the crack appears. In order to explore the potentiality of detecting cracks as they appear without failure or debonding, as well as the compatibility of the OBR bonding to the concrete surfaces, this paper shows the test carried out in the loading up to failure of a concrete slab.

Villalba, Sergi; Casas, Joan R.

2013-08-01

195

Omnidirectional fiber optic tiltmeter  

Science.gov (United States)

A tiltmeter is provided which is useful in detecting very small movements such as earth tides. The device comprises a single optical fiber, and an associated weight affixed thereto, suspended from a support to form a pendulum. A light source, e.g., a light emitting diode, mounted on the support transmits light through the optical fiber to a group of further optical fibers located adjacent to but spaced from the free end of the single optical fiber so that displacement of the single optical fiber with respect to the group will result in a change in the amount of light received by the individual optical fibers of the group. Photodetectors individually connectd to the fibers produce corresponding electrical outputs which are differentially compared and processed to produce a resultant continuous analog output representative of the amount and direction of displacement of the single optical fiber.

Benjamin, B.C.; Miller, H.M.

1983-06-30

196

Polymer optical fiber fuse  

OpenAIRE

Although high-transmission-capacity optical fibers are in demand, the problem of the fiber fuse phenomenon needs to be resolved to prevent the destruction of fibers. As polymer optical fibers become more prevalent, clarifying their fuse properties has become important. Here, we experimentally demonstrate a fuse propagation velocity of 21.9 mm/s, which is 1 to 2 orders of magnitude slower than that in standard silica fibers. The achieved threshold power density and proportion...

Mizuno, Yosuke; Hayashi, Neisei; Tanaka, Hiroki; Nakamura, Kentaro

2013-01-01

197

Statistical mapping of zones of focused groundwater/surface-water exchange using fiber-optic distributed temperature sensing  

Science.gov (United States)

Fiber-optic distributed temperature sensing (FO-DTS) increasingly is used to map zones of focused groundwater/surface-water exchange (GWSWE). Previous studies of GWSWE using FO-DTS involved identification of zones of focused GWSWE based on arbitrary cutoffs of FO-DTS time-series statistics (e.g., variance, cross-correlation between temperature and stage, or spectral power). New approaches are needed to extract more quantitative information from large, complex FO-DTS data sets while concurrently providing an assessment of uncertainty associated with mapping zones of focused GSWSE. Toward this end, we present a strategy combining discriminant analysis (DA) and spectral analysis (SA). We demonstrate the approach using field experimental data from a reach of the Columbia River adjacent to the Hanford 300 Area site. Results of the combined SA/DA approach are shown to be superior to previous results from qualitative interpretation of FO-DTS spectra alone.

Mwakanyamale, Kisa; Day-Lewis, Frederick D.; Slater, Lee D.

2013-01-01

198

Geothermal point sources identified in a fumarolic ice cave on Erebus volcano, Antarctica using fiber optic distributed temperature sensing  

Science.gov (United States)

Degassing of CO2 on the flanks of the active Erebus volcano is thought to occur mainly through fumarolic ice caves (FIC) and associated fumarolic ice towers. There is also minor CO2 degassing from isolated areas of warm ground. The mechanism supplying heat and CO2 gas into the FIC is poorly understood. To investigate this system, a fiber optic distributed temperature sensing (DTS) system was deployed in a FIC to obtain temperature measurements every meter. The DTS data reveal that localized gas vents (GV) supply heat to the FIC air mass and are an important component of the FIC microclimate. FIC temperature is anti-correlated with local atmospheric pressure, indicating barometric pumping of the GV. These results enable the use of FIC temperature as a proxy for flank degassing rate on Erebus, and represent the first application of DTS for monitoring an active volcano.

Curtis, Aaron; Kyle, Philip

2011-08-01

199

An Efficient Wavelength variation approach for Bend Sensing in Single mode-Multimode-Single mode Optical Fiber Sensors  

Directory of Open Access Journals (Sweden)

Full Text Available Several aspects of the SMS edge filters have been investigated, including the effect of bending the SMS fiber cores due to fabrication tolerances, polarization dependence, and temperature dependence. These aspects can impair the performance of a wavelength measurement system. There are several approaches which have been proposed and demonstrated to achieve high resolution and accuracy of wavelength measurement. Bending effects due to the splicing process on the spectral characteristics of SMS fibre structure-based edge filters are investigated experimentally with the help of MATLAB. A limit for the tolerable of the cores of an SMS fibre structure-based edge filter is proposed, beyond which the edge filter’s spectral performance degrades unacceptably. We use Wavelength variation approach by which we reduce the power loss due to the bending in the optical fiber. Due to the power loss the power transmission is increases and efficiency reduces. So by wavelength variation approach we developed an efficient spectrometer capable of performing a wide variety of coherent multidimensional measurements at optical wavelengths. In this approach we fixed the power and perform variation in the wavelength to sense the bending accurately. The two major components of the largely automated device are a spatial beam shaper which controls the beam geometry and a spatiotemporal pulse shaper which controls the temporal waveform of the femtosecond pulse in each beam. By which we sense the distortion to reduce the power transmission. We apply our algorithm for performing several comparison considerations which shows the performance of our algorithm which is better in comparison to the previous work.

Abdul Samee Khan

2012-09-01

200

[The recent development of fiber-optic chemical sensor].  

Science.gov (United States)

The present article provides a brief review of recent research on fiber-optic chemical sensor technology and the future development trends. Especially, fiber-optic pH chemical sensor, fiber-optic ion chemicl sensor, and fiber-optic gas chemical sensor are introduced respectively. Sensing film preparation methods such as chemical bonding method and sol-gel method were briefly reviewed. The emergence of new type fiber-microstructured optical fiber opened up a new development direction for fiber-optic chemical sensor. Because of its large inner surface area, flexible design of structure, having internal sensing places in fibers, it has rapidly become an important development direction and research focus of the fiber-optic chemical sensors. The fiber-optic chemical sensor derived from microstructured optical fiber is also discussed in detail. Finally, we look to the future of the fiber-optic chemical sensor. PMID:25508709

Wang, Jian; Wei, Jian-ping; Yang, Bo; Gao, Zhi-yang; Zhang, Li-wei; Yang, Xue-feng

2014-08-01

201

Polymer optical fibers integrated directly into 3D orthogonal woven composites for sensing  

Science.gov (United States)

This study demonstrates that standard polymer optical fibers (POF) can be directly integrated into composites from 3D orthogonal woven preforms during the weaving process and then serve as in-situ sensors to detect damage due to bending or impact loads. Different composite samples with embedded POF were fabricated of 3D orthogonal woven composites with different parameters namely number of y-/x-layers and x-yarn density. The signal of POF was not affected significantly by the preform structure. During application of resin using VARTM technique, significant drop in backscattering level was observed due to pressure caused by vacuum on the embedded POF. Measurements of POF signal while in the final composites after resin cure indicated that the backscattering level almost returned to the original level of un-embedded POF. The POF responded to application of bending and impact loads to the composite with a reduction in the backscattering level. The backscattering level almost returned back to its original level after removing the bending load until damage was present in the composite. Similar behavior occurred due to impact events. As the POF itself is used as the sensor and can be integrated throughout the composite, large sections of future 3D woven composite structures could be monitored without the need for specialized sensors or complex instrumentation.

Hamouda, Tamer; Seyam, Abdel-Fattah M.; Peters, Kara

2015-02-01

202

Monitoring of Thermal Protection Systems and MMOD using Robust Self-Organizing Optical Fiber Sensing Networks  

Science.gov (United States)

The general aim of this work is to develop and demonstrate a prototype structural health monitoring system for thermal protection systems that incorporates piezoelectric acoustic emission (AE) sensors to detect the occurrence and location of damaging impacts, such as those from Micrometeoroid Orbital Debris (MMOD). The approach uses an optical fiber Bragg grating (FBG) sensor network to evaluate the effect of detected damage on the thermal conductivity of the TPS material. Following detection of an impact, the TPS would be exposed to a heat source, possibly the sun, and the temperature distribution on the inner surface in the vicinity of the impact measured by the FBG network. A similar procedure could also be carried out as a screening test immediately prior to re-entry. The implications of any detected anomalies in the measured temperature distribution will be evaluated for their significance in relation to the performance of the TPS during reentry. Such a robust TPS health monitoring system would ensure overall crew safety throughout the mission, especially during reentry.

Richards, Lance

2014-01-01

203

Power loss characteristics of a sensing element based on a grooved polymer optical fiber under elongation  

International Nuclear Information System (INIS)

This study conducts a numerical and experimental investigation into the effects of elongation on the power attenuation characteristics of grooved polymer optical fibers (POFs). POFs with groove depths ranging from 0 to 1.1 mm are tensile tested. The load–elongation data are then used to compute the corresponding average plastic energy density (APED). An elastic–plastic three-dimensional finite element model is used to simulate the deformation which takes place near the grooved region of the elongated POF in order to clarify the experimental results. In general, the results show that the change rate of the power ratio or the sensitivity increases with increasing elongation and increasing groove depth. By applying a curve-fitting technique, an empirical expression is developed to relate the power ratio to the APED and the groove depth. It is found that the difference between the predicted values obtained from the proposed equation and the experimental results is less than 7%, thus confirming the APED to be a meaningful index with which to evaluate the sensitivity of POF sensors

204

A Bragg Wavelength-Insensitive Fiber Bragg Grating Ultrasound Sensing System that Uses a Broadband Light and No Optical Filter  

Directory of Open Access Journals (Sweden)

Full Text Available An optical filter is incorporated in a conventional ultrasound detection system that uses a fiber Bragg grating (FBG and broadband light source, to demodulate the FBG sensor signal. A novel ultrasound sensing system that does not require an optical filter is presented herein. Ultrasound could be detected via the application of signal processing techniques, such as signal averaging and frequency filters, to the photodetector output that corresponds to the intensity of the reflected light from a broadband light-illuminated FBG. Ultrasonic sensitivity was observed to be enhanced when an FBG was installed as a resonant sensor. This FBG ultrasound detection system is small and cheap to fabricate because it does not use a demodulating optical filter. The experimental results demonstrate that this system could be applied to ultrasonic damage inspection and acoustic emission measurements. Furthermore, this system was able to detect ultrasound despite the amount of strain or temperature that was applied to the FBG sensor because the ultrasound detection was not sensitive to the Bragg wavelength of the FBG sensor.

Hiroshi Tsuda

2011-07-01

205

Optical Fiber Fusion Splicing  

CERN Document Server

This book is an up-to-date treatment of optical fiber fusion splicing incorporating all the recent innovations in the field. It provides a toolbox of general strategies and specific techniques that the reader can apply when optimizing fusion splices between novel fibers. It specifically addresses considerations important for fusion splicing of contemporary specialty fibers including dispersion compensating fiber, erbium-doped gain fiber, polarization maintaining fiber, and microstructured fiber. Finally, it discusses the future of optical fiber fusion splicing including silica and non-silica based optical fibers as well as the trend toward increasing automation. Whilst serving as a self-contained reference work, abundant citations from the technical literature will enable readers to readily locate primary sources.

Yablon, Andrew D

2005-01-01

206

Full-scale prestress loss monitoring of damaged RC structures using distributed optical fiber sensing technology.  

Science.gov (United States)

For the safety of prestressed structures, prestress loss is a critical issue that will increase with structural damage, so it is necessary to investigate prestress loss of prestressed structures under different damage scenarios. Unfortunately, to date, no qualified techniques are available due to difficulty for sensors to survive in harsh construction environments of long service life and large span. In this paper, a novel smart steel strand based on the Brillouin optical time domain analysis (BOTDA) sensing technique was designed and manufactured, and then series of tests were used to characterize properties of the smart steel strands. Based on prestress loss principle analysis of damaged structures, laboratory tests of two similar beams with different damages were used to verify the concept of full-scale prestress loss monitoring of damaged reinforced concrete (RC) beams by using the smart steel strands. The prestress losses obtained from the Brillouin sensors are compared with that from conventional sensors, which provided the evolution law of prestress losses of damaged RC beams. The monitoring results from the proposed smart strand can reveal both spatial distribution and time history of prestress losses of damaged RC beams. PMID:22778590

Lan, Chunguang; Zhou, Zhi; Ou, Jinping

2012-01-01

207

Full-Scale Prestress Loss Monitoring of Damaged RC Structures Using Distributed Optical Fiber Sensing Technology  

Directory of Open Access Journals (Sweden)

Full Text Available For the safety of prestressed structures, prestress loss is a critical issue that will increase with structural damage, so it is necessary to investigate prestress loss of prestressed structures under different damage scenarios. Unfortunately, to date, no qualified techniques are available due to difficulty for sensors to survive in harsh construction environments of long service life and large span. In this paper, a novel smart steel strand based on the Brillouin optical time domain analysis (BOTDA sensing technique was designed and manufactured, and then series of tests were used to characterize properties of the smart steel strands. Based on prestress loss principle analysis of damaged structures, laboratory tests of two similar beams with different damages were used to verify the concept of full-scale prestress loss monitoring of damaged reinforced concrete (RC beams by using the smart steel strands. The prestress losses obtained from the Brillouin sensors are compared with that from conventional sensors, which provided the evolution law of prestress losses of damaged RC beams. The monitoring results from the proposed smart strand can reveal both spatial distribution and time history of prestress losses of damaged RC beams.

Chunguang Lan

2012-04-01

208

Rayleigh fiber optics gyroscope  

OpenAIRE

A novel kind of fiber-optic gyroscope based on Rayleigh backscattering in a fiber-ring resonator is presented in this letter. Information on the rotation rate is obtained from the composed response of the fiber ring to an optical time-domain reflectometry (OTDR) instrument. The developed model based on the coherence properties of the Rayleigh scattering yields a polarization-insensitive and low-cost gyroscope

Kung, A.; Budin, J.; The?venaz, Luc; Robert, P. A.

1997-01-01

209

An Efficient Wavelength variation approach for Bend Sensing in Single mode- Multimode-Single mode Optical Fiber Sensors  

Directory of Open Access Journals (Sweden)

Full Text Available Several aspects of the SMS edge filters have beeninvestigated, including the effect of bending the SMS fibercores due to fabrication tolerances, polarizationdependence, and temperature dependence. These aspectscan impair the performance of a wavelength measurementsystem. There are several approaches which have beenproposed and demonstrated to achieve high resolution andaccuracy of wavelength measurement. Bending effects dueto the splicing process on the spectral characteristics ofSMS fibre structure-based edge filters are investigatedexperimentally with the help of MATLAB. A limit for thetolerable of the cores of an SMS fibre structure-based edgefilter is proposed, beyond which the edge filter’s spectralperformance degrades unacceptably. We use Wavelengthvariation approach by which we reduce the power loss dueto the bending in the optical fiber. Due to the power lossthe power transmission is increases and efficiency reduces.So by wavelength variation approach we developed anefficient spectrometer capable of performing a wide varietyof coherent multidimensional measurements at opticalwavelengths. In this approach we fixed the power andperform variation in the wavelength to sense the bendingaccurately. The two major components of the largelyautomated device are a spatial beam shaper which controlsthe beam geometry and a spatiotemporal pulse shaperwhich controls the temporal waveform of the femtosecondpulse in each beam. By which we sense the distortion toreduce the power transmission. We apply our algorithm forperforming several comparison considerations whichshows the performance of our algorithm which is better incomparison to the previous work

Abdul Samee Khan

2012-09-01

210

Fiber optic laser rod  

Science.gov (United States)

A laser rod is formed from a plurality of optical fibers, each forming an individual laser. Synchronization of the individual fiber lasers is obtained by evanescent wave coupling between adjacent optical fiber cores. The fiber cores are dye-doped and spaced at a distance appropriate for evanescent wave coupling at the wavelength of the selected dye. An interstitial material having an index of refraction lower than that of the fiber core provides the optical isolation for effective lasing action while maintaining the cores at the appropriate coupling distance. 2 figs.

Erickson, G.F.

1988-04-13

211

Fiber optic sensors for nuclear power plants  

International Nuclear Information System (INIS)

Fiber optic sensors are being considered as potential replacements for some of the conventional sensors in the nuclear power industry. Fiber optic sensing technology offers performance enhancements over conventional systems in terms of dynamic range, sensitivity, signal isolation, distributed measurement, reduced size and mass, and resistance to high temperatures, vibration, electromagnetic interference, and radiation. The electronic components of a fiber optic sensing system may be located remotely, allowing installation of the sensing element in electrically noisy, chemically hazardous, or potentially explosive process measurement environments

212

Advanced fiber-optic acoustic sensors  

Science.gov (United States)

Acoustic sensing is nowadays a very demanding field which plays an important role in modern society, with applications spanning from structural health monitoring to medical imaging. Fiber-optics can bring many advantages to this field, and fiber-optic acoustic sensors show already performance levels capable of competing with the standard sensors based on piezoelectric transducers. This review presents the recent advances in the field of fiber-optic dynamic strain sensing, particularly for acoustic detection. Three dominant technologies are identified — fiber Bragg gratings, interferometric Mach-Zehnder, and Fabry-Pérot configurations — and their recent developments are summarized.

Teixeira, João G. V.; Leite, Ivo T.; Silva, Susana; Frazão, Orlando

2014-09-01

213

Fiber optics in SHIVA  

International Nuclear Information System (INIS)

SHIVA is a twenty arm laser which is controlled with a network of fifty computers, interconnected with digital fiber optic links. Three different fiber optic systems employed on the Shiva laser will be described. Two of the systems are for digital communications, one at 9600 baud and the other at 1 megabaud. The third system uses fiber optics to distribute diagnostic triggers with subnanosecond jitter

214

Triboluminescent Fiber-Optic Sensors Measure Stresses  

Science.gov (United States)

Triboluminescence exploited in fiber-optic sensor system for measuring changes in pressures, strains, vibrations, and acoustic emissions, in structural members. Sensors embedded in members for in situ monitoring of condition of structure. System passive in sense no source of radiation required to interrogate optical fiber. Technique has potential for wide range of applications in which detection and measurement of structural stress required.

Rogowski, Robert S.

1994-01-01

215

Soil-embedded optical fiber sensing cable interrogated by Brillouin optical time-domain reflectometry (B-OTDR) and optical frequency-domain reflectometry (OFDR) for embedded cavity detection and sinkhole warning system  

International Nuclear Information System (INIS)

A soil-embedded optical fiber sensing cable is evaluated for an embedded cavity detection and sinkhole warning system in railway tunnels. Tests were performed on a decametric structure equipped with an embedded 110 m long fiber optic cable. Both Brillouin optical time-domain reflectometry (B-OTDR) and optical frequency-domain reflectometry (OFDR) sensing techniques were used for cable interrogation, yielding results that were in good qualitative agreement with finite-element calculations. Theoretical and experimental comparison enabled physical interpretation of the influence of ground properties, and the analysis of embedded cavity size and position. A 5 mm embedded cavity located 2 m away from the sensing cable was detected. The commercially available sensing cable remained intact after soil collapse. Specificities of each technique are analyzed in view of the application requirements. For tunnel monitoring, the OFDR technique was determined to be more viable than the B-OTDR due to higher spatial resolution, resulting in better detection and size determination of the embedded cavities. Conclusions of this investigation gave outlines for future field use of distributed strain-sensing methods under railways and more precisely enabled designing a warning system suited to the Ebersviller tunnel specificities

216

Highly sensitive and simple method for refractive index sensing of liquids in microstructured optical fibers using four-wave mixing  

DEFF Research Database (Denmark)

We present both experimental measurements and simulations for a simple fiber-optical liquid refractive index sensor, made using only commercially available components and without advanced postprocessing of the fiber. Despite the simplicity, we obtain the highest sensitivity experimentally demonstrated to date for aqueous solutions (refractive index around 1.33), which is relevant for extensions to biosensing. The sensor is based on measuring the spectral shift of peaks arising from four-wave mixing (FWM), when filling the holes of a microstructured fiber with different liquid samples and propagating nanosecond pulses through the silica-core of the fiber. To the best of our knowledge, this is also the first experiment where a liquid is filled into the holes of a solid-core microstructured fiber to control the phase-match conditions for FWM. (C) 2011 Optical Society of America

Frosz, Michael Henoch; Stefani, Alessio

2011-01-01

217

Multimode optical fiber  

Energy Technology Data Exchange (ETDEWEB)

A depressed graded-index multimode optical fiber includes a central core, an inner depressed cladding, a depressed trench, an outer depressed cladding, and an outer cladding. The central core has an alpha-index profile. The depressed claddings limit the impact of leaky modes on optical-fiber performance characteristics (e.g., bandwidth, core size, and/or numerical aperture).

Bigot-Astruc, Marianne; Molin, Denis; Sillard, Pierre

2014-11-04

218

Python fiber optic seal  

Energy Technology Data Exchange (ETDEWEB)

Sandia National Laboratories has developed a high security fiber optic seal that incorporates tamper resistance features that are not available in commercial fiber optic seals. The Python Seal is a passive fiber optic loop seal designed to give indication of unauthorized entry. The seal includes a fingerprint feature that provides seal identity information in addition to the unique fiber optic pattern created when the seal is installed. The fiber optic cable used for the seal loop is produced with tamper resistant features that increase the difficulty of attacking that component of a seal. A Seal Reader has been developed that will record the seal signature and the fingerprint feature of the seal. A Correlator software program then compares seal images to establish a match or mismatch. SNL is also developing a Polaroid reader to permit hard copies of the seal patterns to be obtained directly from the seal.

Ystesund, K.; Bartberger, J.; Brusseau, C.; Fleming, P.; Insch, K.; Tolk, K.

1993-08-01

219

Novel monitoring of Antarctic ice shelf basal melting using a fiber-optic distributed temperature sensing mooring  

Science.gov (United States)

Measuring basal melting of ice shelves is challenging and represents a critical component toward understanding ocean-ice interactions and climate change. In November 2011, moorings containing fiber-optic cables for distributed temperature sensing (DTS) were installed through the McMurdo Ice Shelf, Antarctica, (~200 m) and extending ~600 m into the ice shelf cavity. The high spatial resolution of DTS allows for transient monitoring of the thermal gradient within the ice shelf. The gradient near the ice-ocean interface is extrapolated to the in situ freezing temperature in order to continuously track the ice-ocean interface. Seasonal melt rates are calculated to be ~1.0 mm d-1 and 8.6 mm d-1, and maximum melting corresponds to the arrival of seasonal warm surface water in the ice shelf cavity between January and April. The development of continuous, surface-based techniques for measuring basal melting represents a significant advance in monitoring ice shelf stability and ice-ocean interactions.

Kobs, Scott; Holland, David M.; Zagorodnov, Victor; Stern, Alon; Tyler, Scott W.

2014-10-01

220

Remote optical sensing on the nanometer scale with a bowtie aperture nano-antenna on a SNOM fiber tip  

OpenAIRE

Plasmonic nano-antennas have proven the outstanding ability of sensing chemical and physical processes down to the nano-meter scale. Sensing is usually achieved within the highly confined optical fields generated resonantly by the nano-antennas, i.e. in contact to the nano-structures. In these paper, We demonstrate the sensing capability of nano-antennas to their larger scale environment, well beyond their plasmonic confinement volume, leading to the concept of 'remote' (non...

Atie, Elie M.; Xie, Zhihua; Eter, Ali El; Salut, Roland; Nedeljkovic, Dusan; Tannous, Tony; Baida, Fadi I.; Grosjean, Thierry

2015-01-01

221

Optical sensing using fiber Bragg gratings for monitoring structural damage in composite over-wrapped pressure vessels  

Science.gov (United States)

Composite Over-Wrap Vessels are widely used in the aerospace community. They made of thin-walled bottles that are over wrapped with high strength fibers embedded in a matrix material. There is a strong drive to reduce the weight of space borne vehicles and thus pushes designers to adopt COPVs that are over wrapped with graphite fibers embedded in its epoxy matrix. Unfortunately, this same fiber/matrix configuration is more susceptible to impact damage than others and to make matters worse; there is a regime where impacts that damage the over wrap leave no visible scar on the COPV surface. In this paper FBG sensors are presented as a means of monitoring and detecting these types of damage. The FBG sensors are surface mounted to the COPVs and optically interrogated to explore the structural properties of these composite pressure vessels. These gratings optically inscribed into the core of a single mode fiber are used as a tool to monitor the stress strain relation in the composite matrix. The response of these fiber-optic sensors is investigated by pressurizing the cylinder up to its burst pressure of around 4500 psi. A Fiber Optic Demodulation System built by Blue Road Research, is used for interrogation of the Bragg gratings.

Grant, J.

2005-09-01

222

Optical fibers and their applications for radiation measurements  

International Nuclear Information System (INIS)

As a new method of radiation measurements, several optical methods using optical fiber sensors have been developed. One is the application of 'radio-luminescence' from the optical fiber itself such as plastic scintillating fibers. Other researches are made to develop the 'combined-sensors' by combination of optical fibers and scintillating materials. Using the time domain method of optical fiber sensors, the profile of radiation distribution along the optical fiber can be easily determined. A multi-parameter sensing system for measurement of radiation, temperature, stress, etc, are also expected using these optical fiber sensors. (author)

223

Fiber optics for controls  

Science.gov (United States)

The challenge of those involved in control-system hardware development is to accommodate an ever-increasing complexity in aircraft control, while limiting the size and weight of the components and improving system reliability. A technology that displays promise towards this end is the area of fiber optics for controls. The primary advantages of employing optical fibers, passive optical sensors, and optically controlled actuators are weight and volume reduction, immunity from electromagnetic effects, superior bandwidth capabilities, and freedom from short circuits and sparking contacts. Since 1975, NASA Lewis has performed in-house, contract, and grant research in fiber optic sensors, high-temperature electro-optic switches, and fly-by-light control-system architecture. Passive optical sensor development is an essential yet challenging area of work and has therefore received much attention during this period. A major effort to develop fly-by-light control-system technology, known as the Fiber-Optic Control System Integration (FOCSI) program, was initiated in 1985 as a cooperative effort between NASA and DOD. Phase 1 of FOCSI, completed in 1986, was aimed at the design of a fiber-optic integrated propulsion/flight control system. Phase 2, yet to be initiated, will provide subcomponent and system development, and a system engine test. In addition to a summary of the benefits of fiber optics, the FOCSI program, sensor advances, and future directions in the NASA Lewis program will be discussed.

Seng, Gary T.

1987-11-01

224

Development of special optical fibers for evanescent-wave chemical sensing.  

Czech Academy of Sciences Publication Activity Database

Ro?. 49, ?. 5 (1999), s. 883-888. ISSN 0011-4626. [Czech-Chinese Workshop on Advanced Materials for Optoelectronics - AMFO'98. Prague, 15.06.1998-17.06.1998] R&D Projects: GA ?R GA102/98/1358; GA ?R GA102/96/0939 Institutional research plan: CEZ:AV0Z2067918; Joint project No.4104 AS CR and CNRS France Keywords : optical sensors * optical fibres Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 0.328, year: 1999

Mat?jec, Vlastimil; Chomát, Miroslav; Hayer, Miloš; Kašík, Ivan; Berková, Daniela; Abdelmalek, F.; Jaffrezic-Renault, N.

1999-01-01

225

Fiber optics standard dictionary  

CERN Document Server

Fiber Optics Vocabulary Development In 1979, the National Communications System published Technical InfonnationBulle­ tin TB 79-1, Vocabulary for Fiber Optics and Lightwave Communications, written by this author. Based on a draft prepared by this author, the National Communications System published Federal Standard FED-STD-1037, Glossary of Telecommunications Terms, in 1980 with no fiber optics tenns. In 1981, the first edition of this dictionary was published under the title Fiber Optics and Lightwave Communications Standard Dictionary. In 1982, the then National Bureau of Standards, now the National Institute of Standards and Technology, published NBS Handbook 140, Optical Waveguide Communications Glossary, which was also published by the General Services Admin­ istration as PB82-166257 under the same title. Also in 1982, Dynamic Systems, Inc. , Fiberoptic Sensor Technology Handbook, co-authored and edited by published the this author, with an extensive Fiberoptic Sensors Glossary. In 1989, the handbook w...

Weik, Martin H

1997-01-01

226

Fiber Optic Cables  

Science.gov (United States)

This brief interactive activity, by the Electromechanical Digital Library and Wisconsin Technical College System faculty, is an easy-to-use introduction to fiber optic cables and their uses. Students are able to reveal each section at their leisure as they click through the helpful illustrations and animations on fiber optic cable components, LEDâ??s, multi-mode and single-mode cables, and cable connectors. Three review questions wrap up the slide show to test knowledge gained. This would be a great resource for teachers to help introduce the topic to students, or for students to have a comprehensive overview of fiber optic cables.

Bartelt, Terry L. M.

227

Remote open-path cavity-ringdown spectroscopic sensing of trace gases in air, based on distributed passive sensors linked by km-long optical fibers.  

Science.gov (United States)

A continuous-wave, rapidly swept cavity-ringdown spectroscopic technique has been developed for localized atmospheric sensing of trace gases at remote sites. It uses one or more passive open-path optical sensor units, coupled by optical fiber over distances of >1 km to a single transmitter/receiver console incorporating a photodetector and a swept-frequency diode laser tuned to molecule-specific near-infrared wavelengths. Ways to avoid interference from stimulated Brillouin scattering in long optical fibers have been devised. This rugged open-path system, deployable in agricultural, industrial, and natural atmospheric environments, is used to monitor ammonia in air. A noise-limited minimum detectable mixing ratio of ~11 ppbv is attained for ammonia in nitrogen at atmospheric pressure. PMID:24921513

He, Yabai; Jin, Chunjiang; Kan, Ruifeng; Liu, Jianguo; Liu, Wenqing; Hill, Julian; Jamie, Ian M; Orr, Brian J

2014-06-01

228

Novel silica surface charge density mediated control of the optical properties of embedded optically active materials and its application for fiber optic pH sensing at elevated temperatures  

Science.gov (United States)

Silica and silica incorporated nanocomposite materials have been extensively studied for a wide range of applications. Here we demonstrate an intriguing optical effect of silica that, depending on the solution pH, amplifies or attenuates the optical absorption of a variety of embedded optically active materials with very distinct properties, such as plasmonic Au nanoparticles, non-plasmonic Pt nanoparticles, and the organic dye rhodamine B (not a pH indicator), coated on an optical fiber. Interestingly, the observed optical response to varying pH appears to follow the surface charge density of the silica matrix for all the three different optically active materials. To the best of our knowledge, this optical effect has not been previously reported and it appears universal in that it is likely that any optically active material can be incorporated into the silica matrix to respond to solution pH or surface charge density variations. A direct application of this effect is for optical pH sensing which has very attractive features that can enable minimally invasive, remote, real time and continuous distributed pH monitoring. Particularly, as demonstrated here, using highly stable metal nanoparticles embedded in an inorganic silica matrix can significantly improve the capability of pH sensing in extremely harsh environments which is of increasing importance for applications in unconventional oil and gas resource recovery, carbon sequestration, water quality monitoring, etc. Our approach opens a pathway towards possible future development of robust optical pH sensors for the most demanding environmental conditions. The newly discovered optical effect of silica also offers the potential for control of the optical properties of optically active materials for a range of other potential applications such as electrochromic devices.Silica and silica incorporated nanocomposite materials have been extensively studied for a wide range of applications. Here we demonstrate an intriguing optical effect of silica that, depending on the solution pH, amplifies or attenuates the optical absorption of a variety of embedded optically active materials with very distinct properties, such as plasmonic Au nanoparticles, non-plasmonic Pt nanoparticles, and the organic dye rhodamine B (not a pH indicator), coated on an optical fiber. Interestingly, the observed optical response to varying pH appears to follow the surface charge density of the silica matrix for all the three different optically active materials. To the best of our knowledge, this optical effect has not been previously reported and it appears universal in that it is likely that any optically active material can be incorporated into the silica matrix to respond to solution pH or surface charge density variations. A direct application of this effect is for optical pH sensing which has very attractive features that can enable minimally invasive, remote, real time and continuous distributed pH monitoring. Particularly, as demonstrated here, using highly stable metal nanoparticles embedded in an inorganic silica matrix can significantly improve the capability of pH sensing in extremely harsh environments which is of increasing importance for applications in unconventional oil and gas resource recovery, carbon sequestration, water quality monitoring, etc. Our approach opens a pathway towards possible future development of robust optical pH sensors for the most demanding environmental conditions. The newly discovered optical effect of silica also offers the potential for control of the optical properties of optically active materials for a range of other potential applications such as electrochromic devices. Electronic supplementary information (ESI) available: Schematic of the experimental setup, SEM images of the optical fiber sensors, XPS spectra of the sensor materials, as well as additional sensing results from control experiments. See DOI: 10.1039/c4nr06232a

Wang, Congjun; Ohodnicki, Paul R.; Su, Xin; Keller, Murphy; Brown, Thomas D.; Baltrus, John P.

2015-01-01

229

Characterizing fractured rock aquifers using heated Distributed Fiber-Optic Temperature Sensing to determine borehole vertical flow  

Science.gov (United States)

In highly heterogeneous media, fracture network connectivity and hydraulic properties can be estimated using methods such as packer- or cross-borehole pumping-tests. Typically, measurements of hydraulic head or vertical flow in such tests are made either at a single location over time, or at a series of depths by installing a number of packers or raising or lowering a probe. We show how this often encountered monitoring problem, with current solutions sacrificing either one of temporal or spatial information, can be addressed using Distributed Temperature Sensing (DTS). Here, we electrically heat the conductive cladding materials of cables deployed in boreholes to determine the vertical flow profile. We present results from heated fiber optic cables deployed in three boreholes in a fractured rock aquifer at the much studied experimental site near Ploemeur, France, allowing detailed comparisons with alternative methods (e.g. Le Borgne et al., 2007). When submerged in water and electrically heated, the cable very rapidly reaches a steady state temperature (less than 60 seconds). The steady state temperature of the heated cable, measured using the DTS method, is then a function of the velocity of the fluid in the borehole. We find that such cables are sensitive to a wide range of fluid velocities, and thus suitable for measuring both ambient and pumped flow profiles at the Ploemeur site. The cables are then used to monitor the flow profiles during all possible configurations of: ambient flow, cross-borehole- (pumping one borehole, and observing in another), and dipole-tests (pumping one borehole, re-injection in another). Such flow data acquired using DTS may then be used for tomographic flow inversions, for instance using the approach developed by Klepikova et al., (submitted). Using the heated fiber optic method, we are able to observe the flow response during such tests in high spatial detail, and are also able to capture temporal flow dynamics occurring at the start of both the pumping and recovery phase of cross-borehole- and dipole- tests. In addition, the clear advantage of this is that by deploying a single fiber optic cable in multiple boreholes at a site, the flow profiles in all boreholes can be simultaneously measured, allowing many different pumping experiments to be conducted and monitored in a time efficient manner. Klepikova M. V., Le Borgne T., Bour O., and J-R.de Dreuzy, Inverse modelling of flow tomography experiments in fractured media, submitted to Water Resources Research. Le Borgne T., Bour O., Riley M. S., Gouze P., Pezard P.A., Belghoul A., Lods G., Le Provost R., Greswell R. B., Ellis P.A., Isakov E., and B. J. Last, Comparison of alternative methodologies for identifying and characterizing preferential flow paths in heterogeneous aquifers. Journal of Hydrology 2007, 345, 134-148.

Read, T. O.; Bour, O.; Selker, J. S.; Le Borgne, T.; Bense, V.; Hochreutener, R.; Lavenant, N.

2013-12-01

230

Polymer optical fiber fuse  

CERN Document Server

Although high-transmission-capacity optical fibers are in demand, the problem of the fiber fuse phenomenon needs to be resolved to prevent the destruction of fibers. As polymer optical fibers become more prevalent, clarifying their fuse properties has become important. Here, we experimentally demonstrate a fuse propagation velocity of 21.9 mm/s, which is 1 to 2 orders of magnitude slower than that in standard silica fibers. The achieved threshold power density and proportionality constant between the propagation velocity and the power density are respectively 1/186 of and 16.8 times the values for silica fibers. An oscillatory continuous curve instead of periodic voids is formed after the passage of the fuse. An easy fuse termination method is presented herein, along with its potential plasma applications.

Mizuno, Yosuke; Tanaka, Hiroki; Nakamura, Kentaro

2013-01-01

231

Optical fiber head for providing lateral viewing  

Science.gov (United States)

The head of an optical fiber comprising the sensing probe of an optical heterodyne sensing device includes a planar surface that intersects the perpendicular to axial centerline of the fiber at a polishing angle .theta.. The planar surface is coated with a reflective material so that light traveling axially through the fiber is reflected transverse to the fiber's axial centerline, and is emitted laterally through the side of the fiber. Alternatively, the planar surface can be left uncoated. The polishing angle .theta. must be no greater than 39.degree. or must be at least 51.degree.. The emitted light is reflected from adjacent biological tissue, collected by the head, and then processed to provide real-time images of the tissue. The method for forming the planar surface includes shearing the end of the optical fiber and applying the reflective material before removing the buffer that circumscribes the cladding and the core.

Everett, Matthew J. (Livermore, CA); Colston, Billy W. (Livermore, CA); James, Dale L. (Tracy, CA); Brown, Steve (Livermore, CA); Da Silva, Luiz (Danville, CA)

2002-01-01

232

Gas-sensing internal enzyme fiber optic biosensor for hydrogen peroxide.  

Science.gov (United States)

Feasibility is demonstrated for a novel gas-sensing, internal enzyme biosensing scheme for the selective measurement of hydrogen peroxide. Two horseradish peroxidase catalysed reactions are evaluated for the detection of hydrogen peroxide as it crosses a microporous Teflon membrane at 37 degrees C. The rate at which hydrogen peroxide crosses the membrane is determined by either a fluorescence or chemiluminescence measurement and this rate is related to the concentration of hydrogen peroxide in the sample solution. Detection limits of 0.7 mM and 10 muM are estimated for the fluorescence and chemiluminescence methods, respectively. Selectivity is demonstrated for hydrogen peroxide over ascorbic acid, uric acid and tyrosine. PMID:18965999

Arnold, M A; Zhou, X; Petsch, R S

1994-05-01

233

Full-Scale Prestress Loss Monitoring of Damaged RC Structures Using Distributed Optical Fiber Sensing Technology  

OpenAIRE

For the safety of prestressed structures, prestress loss is a critical issue that will increase with structural damage, so it is necessary to investigate prestress loss of prestressed structures under different damage scenarios. Unfortunately, to date, no qualified techniques are available due to difficulty for sensors to survive in harsh construction environments of long service life and large span. In this paper, a novel smart steel strand based on the Brillouin optical time domain analysis...

Chunguang Lan; Zhi Zhou; Jinping Ou

2012-01-01

234

Chemical Sensing Using Fiber Cavity Ring-Down Spectroscopy  

OpenAIRE

Waveguide-based cavity ring-down spectroscopy (CRD) can be used for quantitative measurements of chemical concentrations in small amounts of liquid, in gases or in films. The change in ring-down time can be correlated to analyte concentration when using fiber optic sensing elements that change their attenuation in dependence of either sample absorption or refractive index. Two types of fiber cavities, i.e., fiber loops and fiber strands containing reflective elements, are distinguished. Both ...

Hans-Peter Loock; Barnes, Jack A.; Cheung, Adrienne H.; Jessica Litman; Helen Waechter

2010-01-01

235

Fiber Optical Micro-detectors for Oxygen Sensing in Power Plants  

Energy Technology Data Exchange (ETDEWEB)

Spectroscopy of Mo{sub 6}Cl{sub 12} immobilized in a sol-gel matrix and heated to 200 C has been performed. Oxygen quenching of the luminescence was observed. Aging Mo{sub 6}Cl{sub 12} to temperatures above 250 C converts the canary yellow Mo{sub 6}Cl{sub 12} to a non-luminescent gray solid. Preliminary experiments point to oxidation of the clusters as the likely cause of thermally induced changes in the physical and optical properties of the clusters.

Gregory L. Baker; Ruby N. Ghosh; D. J. Osborn

2003-09-30

236

Fiber optic hydrogen sensor  

Science.gov (United States)

Apparatus and method for detecting a chemical substance by exposing an optic fiber having a core and a cladding to the chemical substance so that the chemical substance can be adsorbed onto the surface of the cladding. The optic fiber is coiled inside a container having a pair of valves for controlling the entrance and exit of the substance. Light from a light source is received by one end of the optic fiber, preferably external to the container, and carried by the core of the fiber. Adsorbed substance changes the transmissivity of the fiber as measured by a spectrophotometer at the other end, also preferably external to the container. Hydrogen is detected by the absorption of infrared light carried by an optic fiber with a silica cladding. Since the adsorption is reversible, a sensor according to the present invention can be used repeatedly. Multiple positions in a process system can be monitored using a single container that can be connected to each location to be monitored so that a sample can be obtained for measurement, or, alternatively, containers can be placed near each position and the optic fibers carrying the partially-absorbed light can be multiplexed for rapid sequential reading, by a single spectrophotometer.

Buchanan, B.R.; Prather, W.S.

1991-01-01

237

Optical Waveguide Sensing and Imaging  

CERN Document Server

The book explores various aspects of existing and emerging fiber and waveguide optics sensing and imaging technologies including recent advances in nanobiophotonics. The focus is both on fundamental and applied research as well as on applications in civil engineering, biomedical sciences, environment, security and defence. The main goal of the multi-disciplinarry team of Editors was to provide an useful reference of state-of-the-art overviews covering a variety of complementary topics on the interface of engineering and biomedical sciences.

Bock, Wojtek J; Tanev, Stoyan

2008-01-01

238

Phase-locking of commercial DFB lasers for distributed optical fiber sensing applications  

Science.gov (United States)

The design of a phase/frequency detector-based optical phase-locked loop (PFD-OPLL) capable of locking two commercial semiconductor distributed feedback (DFB) lasers for the purpose of making Brillouin Optical Time-Domain Analysis (BOTDA) measurements is presented. Due to the aperiodic nature of the PFD transfer characteristic, the PFDOPLL offers strong acquisition performance without requiring additional acquisition hardware. Design constraints due to laser linewidths are relaxed by choosing a damping factor of 3.5 instead of 0.707. Loop stability is ensured by reducing the loop propagation delay by as much as possible in hardware, and choosing the loop natural frequency such that the loop bandwidth is below the FM phase reversal frequency of the laser. Results show stable lock performance at 11 GHz with a phase noise of -70dBc/Hz at a 100 Hz offset, a capture range of 2.5 GHz and a tuning range of 3.3 GHz. These specifications exceed the performance requirements of a BOTDA system.

Rouse, Chris D.; Brown, Anthony W.; Wylie, Michael T. V.; Colpitts, Bruce G.

2011-05-01

239

Optical remote sensing  

CERN Document Server

Optical remote sensing relies on exploiting multispectral and hyper spectral imagery possessing high spatial and spectral resolutions respectively. These modalities, although useful for most remote sensing tasks, often present challenges that must be addressed for their effective exploitation. This book presents current state-of-the-art algorithms that address the following key challenges encountered in representation and analysis of such optical remotely sensed data: challenges in pre-processing images, storing and representing high dimensional data, fusing different sensor modalities, patter

Prasad, Saurabh; Chanussot, Jocelyn

2011-01-01

240

Precision Fiber Optic Sensor Market Forecast  

Science.gov (United States)

The worldwide market for precision fiber optic sensors is forecasted, 1984-1994. The forecast is based upon o Analysis of fiber optic sensor and related component current technology, and a forecast of technology advancement o Review and projection of demand for precision sensing, and the penetration which fiber optics will make into this market The analysis and projections are based mainly on interviews conducted worldwide with research teams, government agencies, systems contractors, medical and industrial laboratories, component suppliers and others. The worldwide market for precision (interferometric) fiber optic sensing systems is forecasted to exceed $0.8 billion by 1994. The forecast is segmented by geographical region (Europe, Japan and North America) and by function; o Gyroscope o Sonar o Gradiometer/Magnetometer o Other - Chemical Composition - Atmospheric Acoustic - Temperature - Position - Pressure Requirements for components are reviewed. These include special fiber, emitters and detectors, modulators, couplers, switches, integrated optical circuits and integrated optoelectronics. The advancement in component performance is forecasted. The major driving forces creating fiber optic sensor markets are reviewed. These include fiber optic sensor technical and economic advantages, increasingly stringent operational requirements, and technology evolution. The leading fiber optic sensor and related component development programs are reviewed. Component sources are listed. Funding sources for sensor and component development are outlined, and trends forecasted.

Montgomery, Jeff D.; Glasco, Jon; Dixon, Frank W.

1986-01-01

241

Chalcogenide glass optical fibers  

Science.gov (United States)

Amorphous Materials (AMI) has served since 1977 as a source of high purity, optically homogeneous plates of selenium-based glasses used in passive IR (FLIR) night vision systems. Over the past three years, Amorphous Materials has used this chalcogenide glass technology and capability to develop a unique process to prepare optical fibers. The process is based on using 2 inch cores removed from a homogeneous plate and sealed in a chamber which can be heated so that fibers may be pulled from a small tube in the bottom. Methods for cladding and coating with thermal plastic using split dies have been developed. The method has been used to produce flexible, low attenuation fibers based on an As-Se-Te composition. High purity As2S3 glass has been used to produce fibers capable of transmitting substantial amounts of IR laser energy. Physical properties of both fibers are discussed.

Hilton, Albert R., Sr.

1992-01-01

242

Nonadiabatic tapered optical fiber for biosensor applications  

Science.gov (United States)

A brief review on biconical tapered fiber sensors for biosensing applications is presented. A variety of configurations and formats of this sensor have been devised for label free biosensing based on measuring small refractive index changes. The biconical nonadiabatic tapered optical fiber offers a number of favorable properties for optical sensing, which have been exploited in several biosensing applications, including cell, protein, and DNA sensors. The types of these sensors present a low-cost fiber biosensor featuring a miniature sensing probe, label-free direct detection, and high sensitivity.

Latifi, Hamid; Zibaii, Mohammad I.; Hosseini, Seyed M.; Jorge, Pedro

2012-12-01

243

Silicon fiber optic sensors  

Science.gov (United States)

A Fabry-Perot cavity is formed by a partially or wholly reflective surface on the free end of an integrated elongate channel or an integrated bounding wall of a chip of a wafer and a partially reflective surface on the end of the optical fiber. Such a constructed device can be utilized to detect one or more physical parameters, such as, for example, strain, through the optical fiber using an optical detection system to provide measuring accuracies of less than aboutb0.1%.

Pocha, Michael D. (Livermore, CA); Swierkowski, Steve P. (Livermore, CA); Wood, Billy E. (Livermore, CA)

2007-10-02

244

Electrospun amplified fiber optics.  

Science.gov (United States)

All-optical signal processing is the focus of much research aiming to obtain effective alternatives to existing data transmission platforms. Amplification of light in fiber optics, such as in Erbium-doped fiber amplifiers, is especially important for efficient signal transmission. However, the complex fabrication methods involving high-temperature processes performed in a highly pure environment slow the fabrication process and make amplified components expensive with respect to an ideal, high-throughput, room temperature production. Here, we report on near-infrared polymer fiber amplifiers working over a band of ?20 nm. The fibers are cheap, spun with a process entirely carried out at room temperature, and shown to have amplified spontaneous emission with good gain coefficients and low levels of optical losses (a few cm(-1)). The amplification process is favored by high fiber quality and low self-absorption. The found performance metrics appear to be suitable for short-distance operations, and the large variety of commercially available doping dyes might allow for effective multiwavelength operations by electrospun amplified fiber optics. PMID:25710188

Morello, Giovanni; Camposeo, Andrea; Moffa, Maria; Pisignano, Dario

2015-03-11

245

Longitudinally Graded Optical Fibers  

Science.gov (United States)

Described herein, for the first time to the best of our knowledge, are optical fibers possessing significant compositional gradations along their length due to longitudinal control of the core glass composition. More specifically, MCVD-derived germanosilicate fibers were fabricated that exhibited a gradient of up to about 0.55 weight percent GeO2 per meter. These gradients are about 1900 times greater than previously reported for fibers possessing longitudinal changes in composition. The refractive index difference is shown to change by about 0.001, representing a numerical aperture change of about 10%, over a fiber length of less than 20 m. The lowest attenuation measured from the present longitudinally-graded fiber (LGF) was 82 dB/km at a wavelength of 1550 nm, though this is shown to result from extrinsic process-induced factors and could be reduced with further optimization. The stimulated Brillouin scattering (SBS) spectrum from the LGF exhibited a 4.4 dB increase in the spectral width, and thus reduction in Brillouin gain, relative to a standard commercial single mode fiber, over a fiber length of only 17 m. Fibers with longitudinally uniform (i.e., not gradient) refractive index profiles but differing chemical compositions among various core layers were also fabricated to determine acoustic effects of the core slug method. The refractive index of the resulting preform varies by about +/- 0.00013 from the average. Upon core drilling, it was found that the core slugs had been drilled off-center from the parent preform, resulting in semi-circular core cross sections that were unable to guide light. As a result, optical analysis could not be conducted. Chemical composition data was obtained, however, and is described herein. A third fiber produced was actively doped with ytterbium (Yb3 ) and fabricated similarly to the previous fibers. The preforms were doped via the solution doping method with a solution of 0.015 M Yb 3 derived from ytterbium chloride hexahydrate and 0.30 M Al 3 derived from aluminum chloride hexahydrate. The doped preform was engineered to have two core layers of differing chemical composition, resulting in both a gradient refractive index profile as well as a gradient acoustic profile. While exhibiting higher loss than the original LGF, the Yb 3-doped fiber showed slightly better SBS suppression with preliminary calculations showing at least 6 dB reduction in Brillouin gain. Lastly, reported here is a straight-forward and flexible method to fabricate silica optical fibers of circular cladding cross-section and rectilinear cores whose aspect ratio and refractive index profile changes with position along the fiber in a deterministic way. Specifically, a modification to the process developed to produce longitudinally-graded optical fibers, was employed. Herein reported are MCVD-derived germanosilicate fibers with rectangular cores where the aspect ratio changes by nearly 200 % and the average refractive index changed by about 5 %. Fiber losses were measured to be about 50 dB/km. Such rectangular core fibers are useful for a variety of telecommunication and biomedical applications and the dimensional and optical chirp provides a deterministic way to control further the modal properties of the fiber. Possible applications of longitudinally graded optical fibers and future improvements are also discussed. The methods employed are very straight-forward and technically simple, providing for a wide variety of longitudinal refractive index and acoustic velocity profiles, as well as core shapes, that could be especially valuable for SBS suppression in high energy laser systems. Next generation analogs, with longitudinally-graded compositional profiles that are very reasonable to fabricate, are shown computationally to be more effective at suppressing SBS than present alternatives, such as externally-applied temperature or strain gradients.

Evert, Alexander George

246

Fiber optic gas sensor  

Science.gov (United States)

A gas sensor includes an in-fiber resonant wavelength device provided in a fiber core at a first location. The fiber propagates a sensing light and a power light. A layer of a material is attached to the fiber at the first location. The material is able to absorb the gas at a temperature dependent gas absorption rate. The power light is used to heat the material and increases the gas absorption rate, thereby increasing sensor performance, especially at low temperatures. Further, a method is described of flash heating the gas sensor to absorb more of the gas, allowing the sensor to cool, thereby locking in the gas content of the sensor material, and taking the difference between the starting and ending resonant wavelengths as an indication of the concentration of the gas in the ambient atmosphere.

Chen, Peng (Inventor); Buric, Michael P. (Inventor); Swinehart, Philip R. (Inventor); Maklad, Mokhtar S. (Inventor)

2010-01-01

247

Theoretical understanding of an alternating dielectric multilayer-based fiber optic SPR sensor and its application to gas sensing  

International Nuclear Information System (INIS)

In the present work, a detailed theoretical analysis of a surface plasmon resonance (SPR)-based fiber optic sensor with an alternating dielectric multilayer system is carried out. The dielectric system consists of silica and titanium oxide layers. The effect of critical design parameters on the sensor's sensitivity and detection accuracy is studied. The results are explained in terms of appropriate physical phenomena, wherever required. Based on the analysis, a new design of a fiber optic SPR sensor for gas detection is proposed. The analysis of such a gas sensor is carried out for four metals separately for a clear understanding. The proposed gas sensor is able to provide reasonably high values of all the performance parameters simultaneously, as required for an efficient detection of gaseous media

248

River Temperature Dynamics and Habitat Characteristics as Predictors of Salmonid Abundance using Fiber-Optic Distributed Temperature Sensing  

Science.gov (United States)

Salmonids require cool water for all life stages, including spawning and growth. Excessive water temperature causes reduced growth and increased disease and mortality. During the summer, salmonids seek local zones of cooler water as a refuge from elevated temperatures. They also prefer specific habitat features such as boulders and overhanging vegetation. The purpose of this study is to determine whether temperature dynamics or commonly measured fish habitat metrics best explain salmonid abundance. The study site was a 2-kilometer reach of the Walla Walla River near Milton-Freewater, OR, USA, which provides habitat for the salmonids chinook salmon (Oncorhynchus tshawytscha), steelhead/rainbow trout (Oncorhynchus mykiss), mountain whitefish (Prosopium williamsoni), and the endangered bull trout (Salvelinus confluentus). The Walla Walla River is listed as an impaired water body under section 303(d) of the Clean Water Act due to temperature. The associated total maximum daily load (TMDL) calls for temperatures to be below 18 °C at all times for salmonid rearing and migration; however, river temperatures surpassed 24 °C in parts of the study reach in 2009. The two largest factors contributing to the warmer water are reduced riparian vegetation, which decreases shading and increases direct solar radiation, and decreased summer flows caused by diversions and irrigation for agriculture. Fiber-optic distributed temperature sensing has emerged as a unique and powerful tool for ecological applications because of its high spatial and temporal resolution. In this study, meter-scale temperature measurements were obtained at 15-minute intervals along the length of the study reach, allowing for the detection and quantification of cold water inflows during the summer of 2009. The cold water inflows were classified as groundwater or hyporheic sources based on the diurnal temperature patterns. Snorkel surveys were conducted in mid-July and mid-August, 2009 to enumerate salmonid abundance in 23 pools. Fish habitat metrics were quantified for each pool by visual estimation. Regression analysis suggests that temperature-related variables explain fish abundance better than habitat variables, and that salmonids' affinity for cold water refuge may be enhanced following periods of high temperature approaching the lethal threshold.

Gryczkowski, L.; Gallion, D.; Haeseker, S.; Bower, R.; Collier, M.; Selker, J. S.; Scherberg, J.; Henry, R.

2011-12-01

249

Respiratory function monitoring using a real-time three-dimensional fiber-optic shaping sensing scheme based upon fiber Bragg gratings  

Science.gov (United States)

An array of in-line curvature sensors on a garment is used to monitor the thoracic and abdominal movements of a human during respiration. The results are used to obtain volumetric changes of the human torso in agreement with a spirometer used simultaneously at the mouth. The array of 40 in-line fiber Bragg gratings is used to produce 20 curvature sensors at different locations, each sensor consisting of two fiber Bragg gratings. The 20 curvature sensors and adjoining fiber are encapsulated into a low-temperature-cured synthetic silicone. The sensors are wavelength interrogated by a commercially available system from Moog Insensys, and the wavelength changes are calibrated to recover curvature. A three-dimensional algorithm is used to generate shape changes during respiration that allow the measurement of absolute volume changes at various sections of the torso. It is shown that the sensing scheme yields a volumetric error of 6%. Comparing the volume data obtained from the spirometer with the volume estimated with the synchronous data from the shape-sensing array yielded a correlation value 0.86 with a Pearson's correlation coefficient p<0.01.

Allsop, Thomas; Bhamber, Ranjeet; Lloyd, Glynn; Miller, Martin R.; Dixon, Andrew; Webb, David; Ania Castañón, Juan Diego; Bennion, Ian

2012-11-01

250

Dosimetry by optical fibers  

International Nuclear Information System (INIS)

The Cea-Leti continues to perfect a prototype system to measure the radioactivity by optical fiber captor, developed in the frame of a collaboration with Cogema, whom one of the objectives is the operational dosimetry of extremities. This experimental device, developed by the Dein, uses a micro detector (diameter 200 ? m) with luminescence optically stimulated (O.S.L.) placed at the extremity of an off-centring optical fiber (40 m for the actual prototype). The detector material is a doped alkaline-earth sulfate, developed by the University of Montpellier. It shows the property to restore the image of absorbed dose under the shape of a visible luminescence when it is submitted to a stimulation in infrared radiation. In the prototype, this stimulation is given by a laser diode coupled to the fiber. Different detector materials have been tested, two have been kept for the prototype development: MgS and CaS. (N.C.)

251

Fluoride glass fiber optics  

CERN Document Server

Fluoride Glass Fiber Optics reviews the fundamental aspects of fluoride glasses. This book is divided into nine chapters. Chapter 1 discusses the wide range of fluoride glasses with an emphasis on fluorozirconate-based compositions. The structure of simple fluoride systems, such as BaF2 binary glass is elaborated in Chapter 2. The third chapter covers the intrinsic transparency of fluoride glasses from the UV to the IR, with particular emphasis on the multiphonon edge and electronic edge. The next three chapters are devoted to ultra-low loss optical fibers, reviewing methods for purifying and

Aggarwal, Ishwar D

1991-01-01

252

Assessment of fiber optic pressure sensors  

International Nuclear Information System (INIS)

This report presents the results of a six-month Phase 1 study to establish the state-of-the-art in fiber optic pressure sensing and describes the design and principle of operation of various fiber optic pressure sensors. This study involved a literature review, contact with experts in the field, an industrial survey, a site visit to a fiber optic sensor manufacturer, and laboratory testing of a fiber optic pressure sensor. The laboratory work involved both static and dynamic performance tests. In addition, current requirements for environmental and seismic qualification of sensors for nuclear power plants were reviewed to determine the extent of the qualification tests that fiber optic pressure sensors may have to meet before they can be used in nuclear power plants. This project has concluded that fiber optic pressure sensors are still in the research and development stage and only a few manufacturers exist in the US and abroad which supply suitable fiber optic pressure sensors for industrial applications. Presently, fiber optic pressure sensors are mostly used in special applications for which conventional sensors are not able to meet the requirements

253

Assessment of fiber optic pressure sensors  

Energy Technology Data Exchange (ETDEWEB)

This report presents the results of a six-month Phase 1 study to establish the state-of-the-art in fiber optic pressure sensing and describes the design and principle of operation of various fiber optic pressure sensors. This study involved a literature review, contact with experts in the field, an industrial survey, a site visit to a fiber optic sensor manufacturer, and laboratory testing of a fiber optic pressure sensor. The laboratory work involved both static and dynamic performance tests. In addition, current requirements for environmental and seismic qualification of sensors for nuclear power plants were reviewed to determine the extent of the qualification tests that fiber optic pressure sensors may have to meet before they can be used in nuclear power plants. This project has concluded that fiber optic pressure sensors are still in the research and development stage and only a few manufacturers exist in the US and abroad which supply suitable fiber optic pressure sensors for industrial applications. Presently, fiber optic pressure sensors are mostly used in special applications for which conventional sensors are not able to meet the requirements.

Hashemian, H.M.; Black, C.L.; Farmer, J.P. [Analysis and Measurement Services Corp., Knoxville, TN (United States)

1995-04-01

254

FOA Lecture 3: Optical Fiber  

Science.gov (United States)

This is Lecture 3 in the FOA Series on fiber optics. This lecture covers optical fiber, how it works, the types of fiber, fiber specifications, and how it is made. Running time for the lecture is 10:39. Flash is required to view the video.

255

Reduced Gravity Zblan Optical Fiber  

Science.gov (United States)

Two optical fiber pullers have been designed for pulling ZBLAN optical fiber in reduced gravity. One fiber puller was designed, built and flown on board NASA's KC135 reduced gravity aircraft. A second fiber puller has been designed for use on board the International Space Station.

Tucker, Dennis S.; Workman, Gary L.; Smith, Guy A.

2000-01-01

256

The Physics of Fiber Optics  

Science.gov (United States)

This module, produced by the Wind Technician TV project from Highland Community College, introduces students to the physics of fiber optics. The module consists of four lessons, which are titled: The physics of fiber optics, Fiber optic fundamentals part 1, Fiber optic fundamentals part 2 and Working with plastic fiber optical fiber. Each lesson has a video or animation to explain the concepts involved, and a skill check feature to assess learning and ensure student grasp the concepts before moving on. A PDF accompanies each lesson, with pertinent images and notes from the video or animation.

257

Optical fiber communications  

CERN Document Server

The fourth edition of this popular text and reference book presents the fundamental principles for understanding and applying optical fiber technology to sophisticated modern telecommunication systems. Optical-fiber-based telecommunication networks have become a major information-transmission-system, with high capacity links encircling the globe in both terrestrial and undersea installations. Numerous passive and active optical devices within these links perform complex transmission and networking functions in the optical domain, such as signal amplification, restoration, routing, and switching. Along with the need to understand the functions of these devices comes the necessity to measure both component and network performance, and to model and stimulate the complex behavior of reliable high-capacity networks.

Keiser, Gerd

2008-01-01

258

Improved Optical Fiber Chemical Sensors  

Science.gov (United States)

Calculations, based on exact theory of optical fiber, have shown how to increase optical efficiency sensitivity of active-core, step-index-profile optical-fiber fluorosensor. Calculations result of efforts to improve efficiency of optical-fiber chemical sensor of previous concept described in "Making Optical-Fiber Chemical Sensors More Sensitive" (LAR-14525). Optical fiber chemical detector of enhanced sensitivity made in several configurations. Portion of fluorescence or chemiluminescence generated in core, and launched directly into bound electromagnetic modes that propagate along core to photodetector.

Egalon, Claudio O.; Rogowski, Robert S.

1994-01-01

259

Fiber optic hydrogen sensors: a review  

Science.gov (United States)

Hydrogen is one of the next generation energies in the future, which shows promising applications in aerospace and chemical industries. Hydrogen leakage monitoring is very dangerous and important because of its low ignition energy, high combustion efficiency, and smallest molecule. This paper reviews the state-of-art development of the fiber optic hydrogen sensing technology. The main developing trends of fiber optic hydrogen sensors are based on two kinds of hydrogen sensitive materials, i.e. palladium-alloy thin films and Pt-doped WO3 coatings. In this review work, the advantages and disadvantages of these two kinds of sensing technologies will be evaluated.

Yang, Minghong; Dai, Jixiang

2014-12-01

260

In-Line Fiber Optic Interferometric Sensors in Single-Mode Fibers  

OpenAIRE

In-line fiber optic interferometers have attracted intensive attention for their potential sensing applications in refractive index, temperature, pressure and strain measurement, etc. Typical in-line fiber-optic interferometers are of two types: Fabry-Perot interferometers and core-cladding-mode interferometers. It’s known that the in-line fiber optic interferometers based on single-mode fibers can exhibit compact structures, easy fabrication and low cost. In this paper...

De-Wen Duan; Min Liu; Di Wu; Tao Zhu

2012-01-01

261

Development and testing of redundant optical fiber sensing systems with self-control, for underground nuclear waste disposal site monitoring. Vol. 1: Summary and evaluation. Final report  

International Nuclear Information System (INIS)

Fiber optic sensors have been developed or further developed, for specific tasks of the research project reported, as for instance detecting and signalling changes of geophysical or geochemical parameters in underground waste storage sites which are of relevance to operating safety. Such changes include e.g. materials dislocations, extensions, temperatures, humidity, pH value and presence of gaseous carbon dioxide and hydrogen. The measuring principle chosen is the fiber Bragg Grating method, as a particularly versatile method easy to integrate into fiber optic networks. After development and successful lab-scale testing of all sensors, except for the gas sensors, field test systems have been made for underground applications and have been tested in situ in the experimental Konrad mine of DBE. Most of the problems discovered with these tests could be resolved within the given project period, so that finally field-test proven sensing systems are available for further activities. The report explains the system performance with a concrete example which shows inter alia beneficial aspects of the system with respect to on-site operation, and the potentials offered in establishing more direct connections between numerical safety analyses and measured results. (orig./CB)

262

Application of Nd/sup 3+/-doped silica fibers to radiation sensing devices  

International Nuclear Information System (INIS)

Applications of rare-earth-ion-doped optical fibers to radiation sensing devices have been studied. It was revealed that rare-earth-ion-doped optical fibers are highly sensitive to radioactive rays such as gamma ray and thermal neutron flux and that they have little dependence on ambient temperature and optical power. An experimental distributed radiation sensing system incorporating Nd/sup 3+/-doped optical fibers, radiation resistant optical fibers and an OTDR was made and tested. The results proved that the distributed sensing system is practically adaptable to the measurement of the radioactive rays

263

Large-strain optical fiber sensing and real-time FEM updating of steel structures under the high temperature effect  

International Nuclear Information System (INIS)

Steel buildings are subjected to fire hazards during or immediately after a major earthquake. Under combined gravity and thermal loads, they have non-uniformly distributed stiffness and strength, and thus collapse progressively with large deformation. In this study, large-strain optical fiber sensors for high temperature applications and a temperature-dependent finite element model updating method are proposed for accurate prediction of structural behavior in real time. The optical fiber sensors can measure strains up to 10% at approximately 700?°C. Their measurements are in good agreement with those from strain gauges up to 0.5%. In comparison with the experimental results, the proposed model updating method can reduce the predicted strain errors from over 75% to below 20% at 800?°C. The minimum number of sensors in a fire zone that can properly characterize the vertical temperature distribution of heated air due to the gravity effect should be included in the proposed model updating scheme to achieve a predetermined simulation accuracy. (paper)

264

New concepts for fiber optic position sensors  

Science.gov (United States)

Digital or ladar fiber optic position sensors may be a promising alternative to electrical LVDT or RVDT for aeronautics. They are rugged devices, they do not need some form of referencing to avoid any error arising from random in-line loss, and they give absolute measurement results. Besides they are to date, the sensors which are the most advanced in tests for aeronautical applications. In this paper we present new concepts for these sensors which make them easier to implement on an aircraft. One of these ideas consists in referencing the optical fiber length from the emitter/receiver to the ladar sensing head, thus making the sensor acquisition independent of the optical fiber length. The other principles which are discussed in this paper concern digital fiber optic sensors. The second concept consists in adding a checksum to each position encoding word in order to test if the measure is valid or not. At last we propose a specific quantization law.

Perraud, Eric

1993-02-01

265

Fiber Optic Testing Course  

Science.gov (United States)

After completing this self-study program you should learn: What needs testing in fiber optics?What equipment is needed to perform the tests? How are these tests performed? What options exist for performing the tests? How are the tests affected by network types (telco, long haul, LAN, FTTx, etc.)? When testing loss, what is the expected value? How accurate are the tests? How can they be made more accurate? What documentation should be kept on the tests? How is troubleshooting done? How does one write a test plan as part of a SOW (scope of work)? What are common mistakes made in testing? What standards apply to testing and how to use them? This extensive page should be useful for students learning more about testing fiber optic systems.

266

Photometric device using optical fibers  

International Nuclear Information System (INIS)

Remote measurements in radioactive environment are now possible with optical fibers. Measurement instruments developed by CEA are constitued of: - an optical probe (5 mm to 1 meter optical path length), - a photometric measurement device, - optical fiber links. 'TELEPHOT' is a photometric device for industrial installations. It is uses interferentiel filters for 2 to 5 simultaneous wave lengths. 'CRUDMETER' measures the muddiness of water. It can be equipped with a high sensitivity cell of 50 cm optical path length tested up to 250 bars. Coupling a double beam spectrophotometer to a remote optical probe, up to 1 meter optical path length, is carried out by means of an optical device using optical fibers links, eventually several hundred meter long. For these equipments special step index large core fibers, 1 to 1.5 mm in diameter, have been developed as well connectors. For industrial control and research these instruments offer new prospect thanks to optical fibers use

267

Online fiber optic spectrophotometry  

Energy Technology Data Exchange (ETDEWEB)

A fiber optic diode array process analyzer has been developed and installed in a radiochemical separations facility at the Savannah River Plant. The analyzer monitors the uranium and nitrate concentration of seven aqueous process streams in a uranium purification process. The analyzer remotely controls the sampling of each process stream and monitors the relative flow rate through each sampler. Spectrophotometric data from the analyzer is processed by multivariate data analysis to give both uranium and nitrate concentrations as well as an indication of the quality of the data. The analyzer system consists of a DuPont Instruments diode array process analyzer, xenon arc lamp, fiber-optic multiplexer, and IBM industrial AT computer. Fused silica optical fibers (600 micrometer core diameter) connect the analyzer to monitor up to ten locations in series. In addition to the seven process locations, the analyzer also monitors a reference optical fiber and an inline uranyl nitrate standard. Process stream samplers are controlled by Opto 22 hardware and electric solenoid valves interfaced to the analyzer computer through an RS-422 communication link. Absorption data from each location is fed into a Partial Least Squares (PLS) model of the uranyl nitrate system for conversion into uranium and nitrate concentrations. The model also outputs a residual variance which is a very sensitive indicator of interferences in the system and is used to verify the quality of the calculated results. Results from the analyzer computer are sent by another Opto 22 interface to a distributed control system which is used to run the uranium purification process. 8 refs., 22 figs., 1 tab.

Van Hare, D.R.; O' Rourke, P.E.; Prather, W.S.

1988-01-01

268

Distributed flow sensing using optical hot -wire grid.  

Science.gov (United States)

An optical hot-wire flow sensing grid is presented using a single piece of self-heated optical fiber to perform distributed flow measurement. The flow-induced temperature loss profiles along the fiber are interrogated by the in-fiber Rayleigh backscattering, and spatially resolved in millimeter resolution using optical frequency domain reflectometry (OFDR). The flow rate, position, and flow direction are retrieved simultaneously. Both electrical and optical on-fiber heating were demonstrated to suit different flow sensing applications. PMID:22513536

Chen, Tong; Wang, Qingqing; Zhang, Botao; Chen, Rongzhang; Chen, Kevin P

2012-04-01

269

Chemical Sensing Using Fiber Cavity Ring-Down Spectroscopy  

Directory of Open Access Journals (Sweden)

Full Text Available Waveguide-based cavity ring-down spectroscopy (CRD can be used for quantitative measurements of chemical concentrations in small amounts of liquid, in gases or in films. The change in ring-down time can be correlated to analyte concentration when using fiber optic sensing elements that change their attenuation in dependence of either sample absorption or refractive index. Two types of fiber cavities, i.e., fiber loops and fiber strands containing reflective elements, are distinguished. Both types of cavities were coupled to a variety of chemical sensor elements, which are discussed and compared.

Hans-Peter Loock

2010-03-01

270

Optical fiber sensors for life support applications  

Science.gov (United States)

Preliminary experimental results on systems designed to demonstrate sensor operation in regenerative food production and crew air supply applications are presented. The systems use conventional fibers and sources in conjunction with custom wavelength division multiplexers in their optical signal processing sections and nonstandard porous optical fibers in the optical sensing elements. It is considered to be possible to create practical sensors for life-support system applications, and particularly, in regenerative food production environments, based on based on reversible sensors for oxygen, carbon monoxide, and humidity.

Lieberman, R. A.; Schmidlin, E. M.; Ferrell, D. J.; Syracuse, S. J.

1992-01-01

271

Fiber optic and laser sensors V; Proceedings of the Meeting, San Diego, CA, Aug. 17-19, 1987  

Science.gov (United States)

The papers contained in this volume focus on recent developments in fiber optic and laser sensors. Topics discussed include electric and magnetic field sensors, fiber optic pressure sensors, fiber optic gyros, fiber optic sensors for aerospace applications, fiber sensor multiplexing, temperature sensors, and specialized fiber optic sensors. Papers are presented on remote fiber optic sensors for angular orientation; fiber optic rotation sensor for space missions; adaptation of an electro-optic monitoring system to aerospace structures; optical fiber sensor for dust concentration measurements; and communication-sensing system using a single optical fiber.

De Paula, Ramon P. (editor); Udd, Eric (editor)

1988-01-01

272

Fiber optic micro sensor for the measurement of tendon forces  

OpenAIRE

Abstract A fiber optic sensor developed for the measurement of tendon forces was designed, numerically modeled, fabricated, and experimentally evaluated. The sensor incorporated fiber Bragg gratings and micro-fabricated stainless steel housings. A fiber Bragg grating is an optical device that is spectrally sensitive to axial strain. Stainless steel housings were designed to convert radial forces applied to the housing into axial forces that could be sensed by the fiber Bragg grating. The meta...

Behrmann Gregory P; Hidler Joseph; Mirotznik Mark S

2012-01-01

273

Optical fiber placement for crossover-free fiber optic gyros  

Science.gov (United States)

Fiber Optic Gyro (FOG) coils have traditionally been produced by cylindrical winding techniques. Regardless of the type of cylindrical wind, standard or quadrupolar, the resulting coils contain fiber crossovers that degrade performance. In 1998, the U.S. Army patented a fiber coil configuration that essentially eliminated crossovers, was thermally symmetric, and allowed the use of inexpensive single-mode (SM) fiber. The crossover-free fiber optic gyro (CFOG) necessitated a paradigm shift in coil production methodology. The CFOG coil design was analyzed in depth to determine manufacturability. Design enhancements were made to enable automated high speed fabrication, resulting in the Improved Crossover-free Fiber Optic Gyro (ICFOG). A prototype Fiber Placement Machine (FPM) was designed and constructed to produce CFOG coils. The fiber placement concept was verified by producing test articles and complete coils.

Williams, Marty

2006-08-01

274

Optical Communication over Plastic Optical Fibers Integrated Optical Receiver Technology  

CERN Document Server

This book presents high-performance data transmission over plastic optical fibers (POF) using integrated optical receivers having good properties with multilevel modulation, i.e. a higher sensitivity and higher data rate transmission over a longer plastic optical fiber length. Integrated optical receivers and transmitters with high linearity are introduced for multilevel communication. For binary high-data rate transmission over plastic optical fibers, an innovative receiver containing an equalizer is described leading also to a high performance of a plastic optical fiber link. The cheap standard PMMA SI-POF (step-index plastic optical fiber) has the lowest bandwidth and the highest attenuation among multimode fibers. This small bandwidth limits the maximum data rate which can be transmitted through plastic optical fibers. To overcome the problem of the plastic optical fibers high transmission loss, very sensitive receivers must be used to increase the transmitted length over POF. The plastic optical fiber li...

Atef, Mohamed

2013-01-01

275

Simulation of a surface plasmon resonance-based fiber-optic sensor for gas sensing in visible range using films of nanocomposites  

International Nuclear Information System (INIS)

A surface plasmon resonance-based fiber-optic sensor coated with nanocomposite film for sensing small concentrations of gases in the visible region of the electromagnetic spectrum has been analyzed. The nanocomposites considered are nanoparticles of Ag, Au and indium tin oxide (ITO) with their varying fraction dispersed in the host dielectric matrix of WO3, SnO2 and TiO2. For analysis, the effective indices of nanocomposites are calculated by adopting the Maxwell–Garnett model for nanoparticles of dimensions much smaller than the wavelength of radiation used for investigation. The effects of the volume fraction of nanoparticles in different nanocomposites and the thickness of the nanocomposite layer on the sensitivity of the sensor have been studied. It has been found that the sensor with the ITO–TiO2 coated nanocomposite with a small volume fraction and optimized film thickness possesses higher sensitivity

276

Selenium semiconductor core optical fibers  

Directory of Open Access Journals (Sweden)

Full Text Available Phosphate glass-clad optical fibers containing selenium (Se semiconductor core were fabricated using a molten core method. The cores were found to be amorphous as evidenced by X-ray diffraction and corroborated by Micro-Raman spectrum. Elemental analysis across the core/clad interface suggests that there is some diffusion of about 3 wt % oxygen in the core region. Phosphate glass-clad crystalline selenium core optical fibers were obtained by a postdrawing annealing process. A two-cm-long crystalline selenium semiconductor core optical fibers, electrically contacted to external circuitry through the fiber end facets, exhibit a three times change in conductivity between dark and illuminated states. Such crystalline selenium semiconductor core optical fibers have promising utility in optical switch and photoconductivity of optical fiber array.

G. W. Tang

2015-02-01

277

Selenium semiconductor core optical fibers  

Science.gov (United States)

Phosphate glass-clad optical fibers containing selenium (Se) semiconductor core were fabricated using a molten core method. The cores were found to be amorphous as evidenced by X-ray diffraction and corroborated by Micro-Raman spectrum. Elemental analysis across the core/clad interface suggests that there is some diffusion of about 3 wt % oxygen in the core region. Phosphate glass-clad crystalline selenium core optical fibers were obtained by a postdrawing annealing process. A two-cm-long crystalline selenium semiconductor core optical fibers, electrically contacted to external circuitry through the fiber end facets, exhibit a three times change in conductivity between dark and illuminated states. Such crystalline selenium semiconductor core optical fibers have promising utility in optical switch and photoconductivity of optical fiber array.

Tang, G. W.; Qian, Q.; Peng, K. L.; Wen, X.; Zhou, G. X.; Sun, M.; Chen, X. D.; Yang, Z. M.

2015-02-01

278

Anisotropic Metamaterial Optical Fibers  

CERN Document Server

Internal physical structure can drastically modify the properties of waveguides: photonic crystal fibers are able to confine light inside a hollow air core by Bragg scattering from a periodic array of holes, while metamaterial loaded waveguides for microwaves can support propagation at frequencies well below cutoff. Anisotropic metamaterials assembled into cylindrically symmetric geometries constitute light-guiding structures that support new kinds of exotic modes. A microtube of anodized nanoporous alumina, with nanopores radially emanating from the inner wall to the outer surface, is a manifestation of such an anisotropic metamaterial optical fiber. The nanopores, when filled with a plasmonic metal such as silver or gold, greatly increase the electromagnetic anisotropy. The modal solutions in anisotropic circular waveguides can be uncommon Bessel functions with imaginary orders.

Pratap, Dheeraj; Pollock, Justin G; Iyer, Ashwin K

2014-01-01

279

Fiber Fizeau interferometer for remote passive sensing  

Science.gov (United States)

Fizeau sensors constitute a large proportion of the fiber optic interferometric type sensors in use today. These include EFPI, FFPI, certain MEMS devices and in-line fiber intrinsic dual-reflector type sensors. The vast majority of the published literature covering these sensor types models them with a "2-beam" interferometer approximation, and implement interrogation approaches considering the same. Analysis performed and results presented show that the 2-beam model is not sufficient when reflection coefficients exceed 1% and traditional quadrature interrogation can result in linearity or distortion errors roughly in directly proportion to the reflectivity coefficients of the Fizeau sensor. A 4-beam multi-path interferometer model is developed and exercised to demonstrate this problem. Further this model shows that the "errors" in comparison to an ideal 2-beam interferometer model are symmetric across the unit circle and suggests that linear interrogation may be accomplished if orthonormal sample sets over the entire unit circle are used to replace the traditional (simple) quadrature sampling. This is shown to be true in both modeling and lab evaluations. The resulting approach has capabilities of remote, passive sensor operation, high frequency response, large, linear dynamic range and low noise. The interrogation technique demonstrated involves a phase generated carrier with full fringe sampling and quadrature determination which cancels the errors experienced from simple quadrature determination. Such an improvement enables higher reflectivity, higher SNR, high-fidelity fiber Fizeau sensor designs. Applications include embedded sensors, line sensors, or mechanically adapted for acoustic, pressure, vibration, acceleration or seismic sensing.

Bush, Jeff; Suh, Kwang

2012-06-01

280

A phase mask fiber grating and sensing applications  

Directory of Open Access Journals (Sweden)

Full Text Available This paper presents an investigation of a fabricated fiber grating device characteristics and its applications, using a phase mask writing technique. The use of a most common UV phase laser (KrF eximer laser, with high intensity light source was focussed to the phase mask for writing on a fiber optic sample. The device (i.e. grating characteristic especially, in sensing application, was investigated. The possibility of using such device for temperature and strain sensors is discussed.

Preecha P. Yupapin

2003-09-01

281

Electronic Fabrication and Fiber Optics  

Science.gov (United States)

This pdf contains a syllabus for a course on electronic fabrication and fiber optics as part of the Aerospace Technology Program. The course provides an introduction to basic soldering, crimping, harnessses, and fiber optics as it applies to the aerospace industry with a focus on the space program. Hands on skill training utilizing electronic parts, soldering stations, multimeter, and fiber optic test equipment is a major part of the course.

282

A novel optical-fiber based surface plasmon resonance sensing architecture and its application to gastric cancer diagnostics  

Science.gov (United States)

The management of threats such as pandemics and explosives, and of health and the environment requires the rapid deployment of highly sensitive detection tools. Sensors based on Surface Plasmon Resonance (SPR) allow rapid, labelfree, highly sensitive detection, and indeed this phenomenon underpins the only label-free optical biosensing technology that is available commercially. In these sensors, the existence of surface plasmons is inferred indirectly from absorption features that correspond to the coupling of light to the surface plasmon. Although SPR is not intrinsically a radiative process, under certain conditions the surface plasmon can itself couple to the local photon states, and emit light. Here we show for the first time that by collecting and characterising this re-emitted light, it is possible to realise new SPR sensing architectures that are more compact, versatile and robust than existing approaches. It is applicable to a range of SPR geometries, including optical fibres. As an example, this approach has been used to demonstrate the detection of a protein identified as a being a biomarker for cancer.

Francois, Alexandre; Boehm, Jonathan; Penno, Megan; Hoffmann, Peter; Monro, Tanya M.

2011-05-01

283

Optimize Etching Based Single Mode Fiber Optic Temperature Sensor  

OpenAIRE

This paper presents a description of etching process for fabrication single mode optical fiber sensors. The process of fabrication demonstrates an optimized etching based method to fabricate single mode fiber (SMF) optic sensors in specified constant time and temperature. We propose a single mode optical fiber based temperature sensor, where the temperature sensing region is obtained by etching its cladding diameter over small length to a critical value. It is observed that th...

Ajay Kumar; Dr. Pramod Kumar

2014-01-01

284

Optical Fiber Sensors for Smart Structures : A Review  

Directory of Open Access Journals (Sweden)

Full Text Available This review describes recent advances in optical fiber sensors for smart structures. After discussing the fabrication on technology and strain sensing of fiber-optic sensors in a brief introduction, the detailed accounts of signal processing techniques employed in them are given. The application areas of fiber-optic sensors are also described briefly with necessary references. Future trend of work is indicated in the concluding remarks.

P. Kundu

2013-04-01

285

Highly flexible short-pulse generation and high sensitivity sensing with stimulated Brillouin scattering in optical fibers  

Science.gov (United States)

We demonstrate two novel types of applications using the same generator as a source for Brillouin multi-wavelength generation. The first is as a highly flexible picosecond pulsed laser source which is tunable in time duration, repetition rate and emission wavelength for optical clock applications in telecommunication. The second application is a high sensitivity distributed Brillouin sensors (DTS) to lower costs and widens the market sector. We demonstrate tunability of the pulsed laser source from ~15 ps down to ~3.5 ps over the whole telecommunications C-band by simply controlling the number of Stokes waves being generated forming a phase-locked Brillouin frequency comb. The repetition rate is the Brillouin frequency shift of ~10 GHz which can be tuned by changing the gain fiber within the cavity. An increase in the standard temperature sensitivity of DTS of ~1.3 MHz/°C by 6 fold is also demonstrated. This increase is of great importance in DTS, since the detection of any variation can be made faster, which can enhance the functionality of such sensors.

Lambin Iezzi, Victor; Loranger, Sébastien; Kashyap, Raman

2014-10-01

286

Chemical vapor deposition of anisotropic ultrathin gold films on optical fibers: real-time sensing by tilted fiber Bragg gratings and use of a dielectric pre-coating  

Science.gov (United States)

Tilted fiber Bragg gratings (TFBGs) are refractometry-based sensor platforms that have been employed herein as devices for the real-time monitoring of chemical vapour deposition (CVD) in the near-infrared range (NIR). The coreguided light launched within the TFBG core is back-reflected off a gold mirror sputtered onto the fiber-end and is scattered out into the cladding where it can interact with a nucleating thin film. Evanescent fields of the growing gold nanostructures behave differently depending on the polarization state of the core-guided light interrogating the growing film, therefore the resulting spectral profile is typically decomposed into two separate peak families for the orthogonal S- and P-polarizations. Wavelength shifts and attenuation profiles generated from gold films in the thickness regime of 5-100 nm are typically degenerate for deposition directly onto the TFBG. However, a polarization-dependence can be imposed by adding a thin dielectric pre-coating onto the TFBG prior to using the device for CVD monitoring of the ultrathin gold films. It is found that addition of the pre-coating enhances the sensitivity of the P-polarized peak family to the deposition of ultrathin gold films and renders the films optically anisotropic. It is shown herein that addition of the metal oxide coating can increase the peak-to-peak wavelength separation between orthogonal polarization modes as well as allow for easy resonance tracking during deposition. This is also the first reporting of anisotropic gold films generated from this particular gold precursor and CVD process. Using an ensemble of x-ray techniques, the local fine structure of the gold films deposited directly on the TFBG is compared to gold films of similar thicknesses deposited on the Al2O3 pre-coated TFBG and witness slides.

Mandia, David J.; Zhou, Wenjun; Ward, Matthew J.; Joress, Howie; Giorgi, Javier B.; Gordon, Peter; Albert, Jacques; Barry, Seán. T.

2014-09-01

287

Hybrid plasmonic terahertz fibers for sensing applications  

OpenAIRE

A novel plasmonic THz fiber featuring two metallic wires in a porous dielectric cladding is studied for resonant sensing applications. In our design, introduction of even lossless analytes into the fiber core leads to significant changes in the modal losses, which is used as a transduction mechanism.

Markov, Andrey; Skorobogatiy, Maksim

2013-01-01

288

Liquid-core Fiber for Temperature Sensing  

Science.gov (United States)

In the paper a intereferometric senser formeasuring temperature by means of liquid-core fiber(LCF)is described. The expriment results and theoretical caculation show that a temperature variation of 1/10000 c can be measured. We have developed a liquid-core multimode fiber. The liquid-core fiber are composed of hollow silica filled of chlorobenzene. High sensitivity is achieved by the intereferometric measuring. It can profitably be employed in spectrum research and sensing.

Wang, Yi-Ding; Wang, Di

2000-04-01

289

A novel differential optical fiber accelerometer  

Science.gov (United States)

The development of sensitive fiber-optic accelerometers is a subject of continuing interest. To acquire high resolution, Michelson phase interferometric techniques are widely adopted. Among the variety structures, the compliant cylinder approach is particularly attractive due to its high sensitivity that is defined as the induced phase shift per applied acceleration. While the two arms of Michelson interferometer should be at the same optical path, it is inconvenient to adjust the two arms' length to equal, also the polarization instability and phase random drift will cause a signal decline. To overcome these limitations, a novel optical fiber accelerometer based on differential interferometric techniques is proposed and investigated. The interferometer is a Sagnac-like white light interferometer, which means the bandwidth of laser spectrum can be as wide as tens nanometers. This interferometer was firstly reported by Levin in 1990s. Lights are divided to two paths before entering the coupler. To induce time difference, one passes through a delay arm and another goes a direct arm. After modulated by the sensing component, they reflect to opposite arm. The sensing part is formed by a seismic mass that is held to only one compliant cylinder, where the single-mode optical fiber is wrapped tightly. When sticking to vibrations, the cylinder compresses or stretches as a spring. The corresponding changes in cylinder circumference lead to strain in the sensing fibers, which is detected as an optical phase shift by the interferometer. The lights from two arms reach the vibration source at different time, sensing a different accelerate speed; produce a different optic path difference. Integrating the dissimilarity of the accelerated speed by time can obtain the total acceleration graph. A shaker's vibration has been tested by the proposed accelerometer referring to a standard piezoelectric accelerometer. A 99.8% linearity of the optical phase shift to the ground acceleration is achieved. The acceleration sensitivity is 300 rad/g. It proves to have a simple structure, good practice, reliable measurement and stable performance.

Pi, Shaohua; Zhao, Jiang; Hong, Guangwei; Jia, Bo

2013-08-01

290

Detection of volatile organic compounds through a sensing film of TiO II doped with organic dyes deposited on an optical fiber  

Science.gov (United States)

The necessity of detection and recognition of different types of gases, such as volatile organic compounds, which are frequently found in food and beverage industries among others, requires the development of different types of sensors. In this work, an application of optical fiber for the detection of volatile organic compounds, particularly ethanol is presented. The sensor was constructed removing a portion of the cladding and depositing instead a sensing titanium dioxide (TiO II) film doped with an organic dye (rhodamine 6G) by the sol-gel method. The sensor response was measured in a Teflon chamber where the sample to be measured was injected. A He-Ne laser beam was coupled to the fiber and the variation in the output power was measured which indicates the gas presence. The difference between the output power with and without gas gives a measure of the concentration that exists in the chamber. The experimental results showed that for an ethanol concentration range from 0 to 10500 ppm, the response of the sensor was approximately linear with a correlation coefficient of 0.9924.

Muñoz A., S.; Ramos M., J.; Martínez H., C.; Castillo M., J.; Beltrán P., G.; Palomino M., R.

2007-03-01

291

Fluorescing optical fibers and uses  

International Nuclear Information System (INIS)

Present available industrial Plastic Optical Fibers are made of an optical core of either Poly Methyl Methacrylate, Polystyrene, or Polycarbonate. Three main fiber families are produced: - transparent fibers, used to transmit light or signals; - scintillating fibers, doped with two or more dopants to let them able to detect particles by radiating blue or green light, measured with a photomultiplier; - fluorescent fibers, doped with a single dopant, and able to shift the ambient incident radiation into another radiation of longer wavelength. New PS core fluorescent fibers are made so far with different absorption and fluorescent reemission wavelength bands. Some optical characteristics of the materials employed for blue, green, yellow, orange fibers are described. Applications in the light sensors field already exist such as light intensity detectors for electric arcs, fog or particle detectors

292

Tackling the Limits of Optical Fiber Links  

CERN Document Server

We theoretically and experimentally investigate relevant noise processes arising in optical fiber links, which fundamentally limit their relative stability. We derive the unsuppressed delay noise for three configurations of optical links: two-way method, Sagnac interferometry, and actively compensated link, respectively designed for frequency comparison, rotation sensing, and frequency transfer. We also consider an alternative two-way setup allowing real-time frequency comparison and demonstrate its effectiveness on a proof-of-principle experiment with a 25-km fiber spool. For these three configurations, we analyze the noise arising from uncommon fiber paths in the interferometric ensemble and design optimized interferometers. We demonstrate interferometers with very low temperature sensitivity of respectively -2.2, -0.03 and 1 fs/K. We use one of these optimized interferometers on a long haul compensated fiber link of 540km. We obtain a relative frequency stability of 3E-20 after 10,000 s of integration time...

Stefani, Fabio; Bercy, Anthony; Lee, Won-Kyu; Chardonnet, Christian; Santarelli, Giorgio; Pottie, Paul-Eric; Amy-Klein, Anne

2014-01-01

293

Harnessing the fiber fuse for sensing applications.  

Science.gov (United States)

A simple refractive index sensor based on a small section of fiber damaged by the fiber fuse is proposed and demonstrated with a sensitivity of 350.58 nm/refractive index unit (RIU). For comparison, a hetero-core structure fiber sensor composed of a short no-core fiber (NCF) sandwiched between two pieces of single-mode fibers is demonstrated with a sensitivity of 157.29 nm/RIU. The fiber fuse technique can allow mass production of sensors by incorporating small sections of the damaged fiber of any type into each device. We believe this is the first application of the periodic damage tracks in optical fibers formed by the fiber fuse. PMID:24787785

Lin, Guei-Ru; Baiad, Mohamad Diaa; Gagne, Mathieu; Liu, Wen-Fung; Kashyap, Raman

2014-04-21

294

Fiber-optic technology review  

International Nuclear Information System (INIS)

A history of fiber technology is presented. The advantages of fiber optics are discussed (bandwidth, cost, weight and size, nonmetallic construction and isolation). Some aspects of the disadvantages of fiber systems briefly discussed are fiber and cable availability, fiber components, radiation effects, receivers and transmitters, and material dispersion. Particular emphasis over the next several years will involve development of fibers and systems optimized for use at wavelengths near 1.3 ?m and development of wavelengths multiplexers for simultaneous system operation at several wavelengths

295

Fiber-diffraction Interferometer using Coherent Fiber Optic Taper  

OpenAIRE

We present a fiber-diffraction interferometer using a coherent fiber optic taper for optical testing in an uncontrolled environment. We use a coherent fiber optic taper and a single-mode fiber having thermally-expanded core. Part of the measurement wave coming from a test target is condensed through a fiber optic taper and spatially filtered from a single-mode fiber to be reference wave. Vibration of the cavity between the target and the interferometer probe is common to bot...

Kihm, Hagyong; Lee, Yun-woo

2010-01-01

296

Few-mode fiber based optical sensors.  

Science.gov (United States)

Few-mode fibers (FMFs) have found applications in optical communications and sensors with attractive features that standard single mode fiber (SSMF) do not possess. We report our recent progress on FMF based optical sensors, and show the potential of utilizing the spatial dimension for multi-parameter sensing with discrimination capability. We first show a discrete type FMF sensor based on interferometer structure with a short FMF, utilizing the modal interference between either the polarizations (x and y) or the spatial modes (LP01 and LP11). We then show a distributed type FMF sensor by generating the stimulated Brillouin scattering (SBS) in a long FMF. We characterize the Brillouin gain spectrum (BGS) with a pump-probe configuration, and measure the temperature and strain coefficients for LP01 and LP11 modes. The proposed FMF based optical sensor can be applied to sensing a wide range of parameters. PMID:25835874

Li, An; Wang, Yifei; Hu, Qian; Shieh, William

2015-01-26

297

Spatial and temporal resolution requirements for quench detection in (RE)Ba2Cu3Ox magnets using Rayleigh-scattering-based fiber optic distributed sensing  

Science.gov (United States)

One of the key remaining challenges to safe and reliable operation of large, high temperature superconductor (HTS)-based magnet systems is quench detection and protection. Due to the slow quench propagation in HTS systems, the conventional discrete voltage-tap approach developed for NbTi and Nb3Sn magnets may not be sufficient. In contrast, a distributed temperature profile, generated by a distributed temperature sensor and facilitating continuous monitoring of the temperature at any monitored locations within a magnet with high spatial resolution, may be required. One such distributed temperature sensing option is the use of Rayleigh-based fiber optic sensors (FOS), which are immune to electromagnetic interference. The detection of a quench via Rayleigh-based FOS relies on converting the spectral shifts in the Rayleigh scattering spectra into temperature variations. As a result, the higher the spatial sampling resolution the larger the data processing volume, and thus the lower the temporal sampling resolution. So, for effective quench detection, which requires the quick and accurate identification of a hot spot, it is important to find a balance between the spatial and temporal resolutions executable on a given data acquisition and processing (DAQ) system. This paper discusses a method for finding an appropriate DAQ technology that matches the characteristic of a superconducting coil, and determining the acceptable resolutions for efficient and safe quench detection. A quench detection algorithm based on distributed temperature sensing is proposed and its implementation challenges are discussed.

Chan, W. K.; Flanagan, G.; Schwartz, J.

2013-10-01

298

Python fiber-optic seal  

Energy Technology Data Exchange (ETDEWEB)

Sandia National Laboratories (SNL) has developed a high-security fiber-optic seal that incorporates tamper-resistance features not available in commercial fiber-optic seals. The Python Seal is a passive fiber-optic loop seal designed to give indication of unauthorized entry. The seal includes a fingerprint feature that provides seal identity information in addition to the unique fiber-optic pattern created when the seal is installed. The fiber-optic cable used for the seal loop is produced with tamper-resistant features that increase the difficulty of attacking this component of a seal. A Seal Reader has been developed that records the seal signature and the fingerprint feature of the seal. A Correlator software program compares seal images to establish a match or mismatch. SNL also is developing a Polaroid Reader to permit hard copies of the seal patterns to be obtained directly from the seal.

Ystesund, K.; Bartberger, J.; Brusseau, C.; Fleming, P.; Insch, K.; Tolk, K. [Sandia National Labs., Albuquerque, NM (United States)

1993-12-31

299

Fiber optic acoustic sensor technology  

Science.gov (United States)

Fiber optic sensor technology has been under development for over 25 years, recently a major milestone has been reached- the introduction of the Fiber Optic Wide Aperture Array on the first Virginia class submarine. This paper will review the development of this technology, outlining the principles of operation and the technological developments that led to fiber optic interferometric sensors becoming viable for production in an advanced sonar system. The Fiber Optic Wide Aperture array is a large channel count planar array mounted on the side of the submarine, but fiber sensor technology is also being developed for both towed arrays (as a replacement for the Navy's thin-line towed arrays) and for bottom mounted acoustic arrays for a number of Navy applications. This paper will describe the development of the fiber optic hydrophones for these applications as well as the optical interrogation techniques. One of the key features of fiber optic sensor technology is the ability to passively multiplex many hydrophone channels per fiber, several multiplexing techniques will also be described. Some of the issues and challenges of this technology, such as coherent noise for large channel count systems will also be briefly discussed.

Cole, James; Kirkendall, Clay; Dandridge, Anthony

2005-04-01

300

Reliability, availability, and maintainability considerations for fiber optical sensor applications  

Science.gov (United States)

The paper gives an overview of reliability, availability, and maintainability of fiber optical sensors, three key factors on which standards and validation should be based and which are required for successful industrialization. The examples given are based on two long term applications with fiber optical Bragg gratings - the surveillance of two bridges (civil engineering). However, similar reflections are required for any type of application and any optical fiber sensors. Recommendations are given to improve the confidence and acceptance of possible users in fiber optical sensing systems. It is shown that with proper installation lifetimes of 50 years are possible.

Brönnimann, Rolf; Held, Marcel; Nellen, Philipp M.

2006-03-01

301

chalcogenide microstructured optical fiber  

Science.gov (United States)

We demonstrate the supercontinuum (SC) generation in a four-hole As2S5 chalcogenide microstructured optical fiber (MOF) experimentally. The As2S5 glass has better property of transmission than As2S3 glass in the visible range. The four-hole As2S5 MOF is fabricated by a rod-in-tube method. The SCs generated by different pump wavelengths at 2,000, 2,300 and 2,500 nm in the MOF whose length is from 2.3 to 20 cm are demonstrated. Those pump wavelengths correspond to the chromatic dispersion wavelength in the normal chromatic dispersion region, the anomalous chromatic dispersion region close to zero-dispersion wavelength (ZDW) and the anomalous chromatic dispersion region far from ZDW, respectively. Wider SCs can be obtained when pumped at a wavelength in the anomalous dispersion region close to ZDW. The widest SC range of 4,280 nm (from 1,370 to 5,650 nm) covering two octaves was obtained in a 4.8-cm-long fiber pumped at 2,300 nm.

Gao, Weiqing; Duan, Zhongchao; Asano, Koji; Cheng, Tonglei; Deng, Dinghuan; Matsumoto, Morio; Misumi, Takashi; Suzuki, Takenobu; Ohishi, Yasutake

2014-09-01

302

Fiber optic hydrogen sensor  

Energy Technology Data Exchange (ETDEWEB)

This report covers the development of fiber optic hydrogen and temperature sensors for monitoring dissolved hydrogen gas in transformer oil. The concentration of hydrogen gas is a measure of the corona and spark discharge within the transformer and reflects the state of health of the transformer. Key features of the instrument include use of palladium alloys to enhance hydrogen sensitivity, a microprocessor controlled instrument with RS-232, liquid crystal readout, and 4-20 ma. current loop interfaces. Calibration data for both sensors can be down loaded to the instrument through the RS-232 interface. This project was supported by the Technology Transfer Initiative in collaboration with J. W. Harley, Inc. through the mechanism of a cooperative research and development agreement (CRADA).

Butler, M.A.; Sanchez, R.; Dulleck, G.R.

1996-05-01

303

Combined electromechanical impedance and fiber optic diagnosis of aerospace structures  

Science.gov (United States)

Electromechanical impedance is a popular diagnostic method for assessing structural conditions at high frequencies. It has been utilized, and shown utility, in aeronautic, space, naval, civil, mechanical, and other types of structures. By contrast, fiber optic sensing initially found its niche in static strain measurement and low frequency structural dynamic testing. Any low frequency limitations of the fiber optic sensing, however, are mainly governed by its hardware elements. As hardware improves, so does the bandwidth (frequency range * number of sensors) provided by the appropriate enabling fiber optic sensor interrogation system. In this contribution we demonstrate simultaneous high frequency measurements using fiber optic and electromechanical impedance structural health monitoring technologies. A laboratory specimen imitating an aircraft wing structure, incorporating surfaces with adjustable boundary conditions, was instrumented with piezoelectric and fiber optic sensors. Experiments were conducted at different structural boundary conditions associated with deterioration of structural health. High frequency dynamic responses were collected at multiple locations on a laboratory wing specimen and conclusions were drawn about correspondence between structural damage and dynamic signatures as well as correlation between electromechanical impedance and fiber optic sensors spectra. Theoretical investigation of the effect of boundary conditions on electromechanical impedance spectra is presented and connection to low frequency structural dynamics is suggested. It is envisioned that acquisition of high frequency structural dynamic responses with multiple fiber optic sensors may open new diagnostic capabilities for fiber optic sensing technologies.

Schlavin, Jon; Zagrai, Andrei; Clemens, Rebecca; Black, Richard J.; Costa, Joey; Moslehi, Behzad; Patel, Ronak; Sotoudeh, Vahid; Faridian, Fereydoun

2014-03-01

304

Shaping of Looped Miniaturized Chalcogenide Fiber Sensing Heads for Mid-Infrared Sensing  

Directory of Open Access Journals (Sweden)

Full Text Available Chalcogenide glass fibers are promising photonic tools to develop Fiber Evanescent Wave Spectroscopy (FEWS optical sensors working in the mid-infrared region. Numerous pioneering works have already been carried out showing their efficiency, especially for bio-medical applications. Nevertheless, this technology remains confined to academic studies at the laboratory scale because chalcogenide glass fibers are difficult to shape to produce reliable, sensitive and compact sensors. In this paper, a new method for designing and fabricating a compact and robust sensing head with a selenide glass fiber is described. Compact looped sensing heads with diameter equal to 2 mm were thus shaped. This represents an outstanding achievement considering the brittleness of such uncoated fibers. FEWS experiments were implemented using alcoholic solutions as target samples showing that the sensitivity is higher than with the routinely used classical fiber. It is also shown that the best compromise in term of sensitivity is to fabricate a sensing head including two full loops. From a mechanical point of view, the breaking loads of the loop shaped head are also much higher than with classical fiber. Finally, this achievement paves the way for the use of mid-infrared technology during in situ and even in vivo medical operations. Indeed, is is now possible to slide a chalcogenide glass fiber in the operating channel of a standard 2.8 mm diameter catheter.

Patrick Houizot

2014-09-01

305

Mid-infrared fiber optics.  

Science.gov (United States)

Fiber optics for carbon dioxide laser surgery have been in developmental research for the past ten years. An up-to-date presentation of infrared fiber optics as they pertain to laser surgery is presented. Optical properties such as intrinsic and extrinsic electronic absorption, multiphonon absorption, and scatter mechanisms are discussed. Real-world considerations for materials selection and fabrication techniques for both crystalline and glassy fiber optics give the reader a perspective regarding the stage of development of these devices. Data are presented indicating transmission ranges and absorption coefficients for both bulk materials and fabricated fiber optics. The conclusions are drawn based on the needs of the clinician as they relate to the degree of existing technology. PMID:3093792

Fuller, T A

1986-01-01

306

Multiplexed fiber optic displacement sensors  

International Nuclear Information System (INIS)

A multiplexed bend loss type single-mode fiber-optic sensor system was prepared to measure the displacement of several cm of the civil engineering structures such as many bridges, tunnels and various buildings. This bend loss type fiber-optic sensor used the signal difference between two reflection signals due to various bend losses generating at a pair of optical connectors by using OTDR (optical time domain reflectometer) for measuring displacements. The experiments were conducted for showing the measurement feasibility on the range of 10 cm, and the multiplexing experiments were also performed to measure the displacements of 5 measuring positions of an object by setting these 5 fiber-optic sensors on a single mode fiber simultaneously.

307

Surface plasmon resonance based fiber optic refractive index sensors  

Science.gov (United States)

Refractive index sensors based on surface plasmon resonance (SPR) in a thin metal film deposited on an unclad core of a multimode fiber are presented. The sensing element of the fiber optic SPR sensors is a bare core of a step-index optical fiber made of fused silica with a double-sided sputtered gold film. First, an in-line transmissionbased sensing scheme with the fiber optic SPR probe is used. Second, a reflection-based sensing scheme with a terminated fiber optic SPR probe is employed. The fiber optic SPR probes have different lengths and the thickness of the sputtered gold film is about 50 nm. Both sensing schemes utilize a wavelength interrogation method so that the refractive index of a liquid is sensed by measuring the position of the dip in the transmitted or reflected spectral intensity distribution. As an example, the aqueous solutions of ethanol with refractive indices in a range from 1.333 to 1.364 are measured. For the transmission-based sensing scheme a polarization-dependent response is revealed.

Hlubina, Petr; Kadulova, Miroslava; Ciprian, Dalibor

2014-12-01

308

Microstructured optical fiber refractive index sensor  

DEFF Research Database (Denmark)

We describe a dual-core microstructured optical fiber designed for refractive index sensing of fluids. We show that by using the exponential dependence of intercore coupling on analyte refractive index, both large range and high sensitivity can be achieved in the one device. We also show that selective filling of the microstructure with analyte can increase the device sensitivity by approximately 1 order of magnitude.

Town, Graham E.; McCosker, Ravi

2010-01-01

309

Sensing via optical interference  

Directory of Open Access Journals (Sweden)

Full Text Available Chemical and biological sensing are problems of tremendous contemporary technological importance in multiple regulatory and human health contexts, including environmental monitoring, water quality assurance, workplace air quality assessment, food quality control, many aspects of biodiagnostics, and, of course, homeland security. Frequently, what is needed, or at least wanted, are sensors that are simultaneously cheap, fast, reliable, selective, sensitive, robust, and easy to use. Unfortunately, these are often conflicting requirements. Over the past few years, however, a number of promising ideas based on optical interference effects have emerged. Each is based to some extent on advances in the design and fabrication of functional materials. Generally, the advances are of two kinds: chemo- and bio-selective recognition and binding, and efficient methods for micropatterning or microstructuring.

Ryan C. Bailey

2005-04-01

310

Radiation damage in optical fibers  

Energy Technology Data Exchange (ETDEWEB)

While plastic-clad-silica (PCS) fiber shows the greatest radiation resistance, PCS fiber has been difficult to reliably connectorize for routine field operations. For this reason, all-glass fibers have been studied as an alternative to PCS. Based on available literature and some preliminary tests at Los Alamos, we have concentrated on fluorosilicate clad, step index, pure silica core fibers. This paper reviews recent laboratory data for these fibers relative to the PCS fibers. This paper also discusses use of a fiber (or any optical medium) on a Cerenkov radiation-to-light transducer. Since the radiation induces attenuation in the medium, the light output is not proportional to the radiation input. The nonlinearity introduced by this attenuation is calculated.

Lyons, P.B.; Looney, L.D.; Ogle, J.W.

1983-01-01

311

Radiation damage in optical fibers  

International Nuclear Information System (INIS)

While plastic-clad-silica (PCS) fiber shows the greatest radiation resistance, PCS fiber has been difficult to reliably connectorize for routine field operations. For this reason, all-glass fibers have been studied as an alternative to PCS. Based on available literature and some preliminary tests at Los Alamos, we have concentrated on fluorosilicate clad, step index, pure silica core fibers. This paper reviews recent laboratory data for these fibers relative to the PCS fibers. This paper also discusses use of a fiber (or any optical medium) on a Cerenkov radiation-to-light transducer. Since the radiation induces attenuation in the medium, the light output is not proportional to the radiation input. The nonlinearity introduced by this attenuation is calculated

312

Efficient fiber-optical interface for nanophotonic devices  

CERN Document Server

We demonstrate a method for efficient coupling of guided light from a single mode optical fiber to nanophotonic devices. Our approach makes use of single-sided conical tapered optical fibers that are evanescently coupled over the last ~10 um to a nanophotonic waveguide. By means of adiabatic mode transfer using a properly chosen taper, single-mode fiber-waveguide coupling efficiencies as high as 97(1)% are achieved. Efficient coupling is obtained for a wide range of device geometries which are either singly-clamped on a chip or attached to the fiber, demonstrating a promising approach for integrated nanophotonic circuits, quantum optical and nanoscale sensing applications.

Tiecke, T G; Thompson, J D; Peyronel, T; de Leon, N P; Vuleti?, V; Lukin, M D

2014-01-01

313

Fiber optic refractive index monitor  

Science.gov (United States)

A sensor for measuring the change in refractive index of a liquid uses the lowest critical angle of a normal fiber optic to achieve sensitivity when the index of the liquid is significantly less than the index of the fiber core. Another embodiment uses a liquid filled core to ensure that its index is approximately the same as the liquid being measured.

Weiss, Jonathan David (Albuquerque, NM)

2002-01-01

314

Mobile fiber optic emission spectrograph  

Energy Technology Data Exchange (ETDEWEB)

Technical Assistance Request HLW/DWPF-TAR-970064 asked SRTC to evaluate the use of a fiber optic coupled emission spectrometer. The spectrometer would provide additional ICP analyses in the DWPF laboratory.

Spencer, W.A.; Coleman, C.J.; McCarty, J.E.; Beck, R.S.

1997-05-01

315

Optimize Etching Based Single Mode Fiber Optic Temperature Sensor  

Directory of Open Access Journals (Sweden)

Full Text Available This paper presents a description of etching process for fabrication single mode optical fiber sensors. The process of fabrication demonstrates an optimized etching based method to fabricate single mode fiber (SMF optic sensors in specified constant time and temperature. We propose a single mode optical fiber based temperature sensor, where the temperature sensing region is obtained by etching its cladding diameter over small length to a critical value. It is observed that the light transmission through etched fiber at 1550 nm wavelength optical source becomes highly temperature sensitive, compared to the temperature insensitive behavior observed in un-etched fiber for the range on 30ºC to 100ºC at 1550 nm. The sensor response under temperature cycling is repeatable and, proposed to be useful for low frequency analogue signal transmission over optical fiber by means of inline thermal modulation approach.

Ajay Kumar

2014-02-01

316

Innovative Plastic Optical Fiber Sensors  

OpenAIRE

This thesis describes the development of new types of fiber optic sensors for the measurement of mechanical quantities such as displacement, vibration and acceleration. Also, it describes the realization of specific acquisition systems designed to interrogate the developed sensors. Since optical fibers have been historically associated with high speed telecommunication links because of their very large bandwidth and low attenuation, there is a great interest for their employment in sensor app...

Casalicchio, Maria Luisa

2012-01-01

317

Light diffusing fiber optic chamber  

Science.gov (United States)

A light diffusion system for transmitting light to a target area. The light is transmitted in a direction from a proximal end to a distal end by an optical fiber. A diffusing chamber is operatively connected to the optical fiber for transmitting the light from the proximal end to the distal end and transmitting said light to said target area. A plug is operatively connected to the diffusing chamber for increasing the light that is transmitted to the target area.

Maitland, Duncan J. (Lafayette, CA)

2002-01-01

318

Small Business Innovations (Fiber Optics)  

Science.gov (United States)

Foster-Miller, Inc. Waltham, MA developed the In-Situ Fiber Optic Polymer Reaction Monitor which could lead to higher yields and lower costs in complex composite manufacturing. The monitor, developed under a Small Business Innovation Research (SBIR) contract with Langley Research Center, uses an infrared, fiber optic sensor to track the molecular vibrational characteristics of a composite part while it is being cured. It is the first analytical system capable of directly measuring the chemistry of advanced composite materials.

1991-01-01

319

Robust Mapping of Incoherent Fiber-Optic Bundles  

Science.gov (United States)

A method and apparatus for mapping between the positions of fibers at opposite ends of incoherent fiber-optic bundles have been invented to enable the use of such bundles to transmit images in visible or infrared light. The method is robust in the sense that it provides useful mapping even for a bundle that contains thousands of narrow, irregularly packed fibers, some of which may be defective. In a coherent fiber-optic bundle, the input and output ends of each fiber lie at identical positions in the input and output planes; therefore, the bundle can be used to transmit images without further modification. Unfortunately, the fabrication of coherent fiber-optic bundles is too labor-intensive and expensive for many applications. An incoherent fiber-optic bundle can be fabricated more easily and at lower cost, but it produces a scrambled image because the position of the end of each fiber in the input plane is generally different from the end of the same fiber in the output plane. However, the image transmitted by an incoherent fiber-optic bundle can be unscrambled (or, from a different perspective, decoded) by digital processing of the output image if the mapping between the input and output fiber-end positions is known. Thus, the present invention enables the use of relatively inexpensive fiber-optic bundles to transmit images.

Roberts, Harry E.; Deason, Brent E.; DePlachett, Charles P.; Pilgrim, Robert A.; Sanford, Harold S.

2007-01-01

320

Magnetic field sensing based on magnetic-fluid-clad fiber-optic structure with taper-like and lateral-offset fusion splicing.  

Science.gov (United States)

A kind of magnetic field sensor composed of magnetic fluid surrounding a segment of singlemode fiber is proposed. The taper-like and lateral-offset fusion splicing techniques are employed. The sensing principle is based on cladding mode interference. The interference valley wavelength or transmission loss of the sensing structure is sensitive to the external magnetic field, which is utilized for magnetic field sensing. The linear response regions are obtained in the range of 38-225 Oe and 250-475 Oe. For the valley-wavelength-shift-type sensing, the sensitivities are 14.1 pm/Oe and 26 pm/Oe at low and high field ranges, respectively. For the transmission-loss-variation-type sensing, the sensitivity of -0.024 dB/Oe is achieved for the magnetic field strength ranging from 250 to 475 Oe. PMID:25320997

Dong, Shaohua; Pu, Shengli; Wang, Haotian

2014-08-11

321

Power system applications of fiber optic sensors  

Science.gov (United States)

This document is a progress report of work done in 1985 on the Communications and Control for Electric Power Systems Project at the Jet Propulsion Laboratory. These topics are covered: Electric Field Measurement, Fiber Optic Temperature Sensing, and Optical Power transfer. Work was done on the measurement of ac and dc electric fields. A prototype sensor for measuring alternating fields was made using a very simple electroscope approach. An electronic field mill sensor for dc fields was made using a fiber optic readout, so that the entire probe could be operated isolated from ground. There are several instances in which more precise knowledge of the temperature of electrical power apparatus would be useful. This report describes a number of methods whereby the distributed temperature profile can be obtained using a fiber optic sensor. The ability to energize electronics by means of an optical fiber has the advantage that electrical isolation is maintained at low cost. In order to accomplish this, it is necessary to convert the light energy into electrical form by means of photovoltaic cells. JPL has developed an array of PV cells in gallium arsenide specifically for this purpose. This work is described.

Johnston, A. R.; Jackson, S. P.; Kirkham, H.; Yeh, C.

1986-01-01

322

Novel optical fiber ultrasonic sensor based on fiber laser  

Science.gov (United States)

Researching high-sensitivity flexible ultrasonic sensor is important in the field of structural health monitoring (SHM). In this research, a novel ultrasonic sensor based on fiber ring laser with an in-built phase shifted fiber Bragg grating (PSFBG) is proposed and demonstrated. The first function of the PS-FBG is to determine the wavelength of the laser. Thus, this sensing system is robust to temperature change and quasi-static strain change because the PS-FBG is always illuminated. The other function of the PS-FBG is a sensor with ultra-steep slope and short effective grating length. It is beneficial for achievement of high-sensitivity and broad-bandwidth ultrasonic detection. The experimental evaluated sensitivity was 58.5+/-3 dB, which is 7.5 dB higher than traditional PZT sensor. This may be the highest sensitivity obtained by optical fiber sensing system. Because of the advantages including robustness, simple structure and low cost in addition to the high sensitivity and broad bandwidth, this sensing system has potential practical applications in ultrasonic SHM.

Wu, Qi; Okabe, Yoji; Sun, Junqiang

2014-03-01

323

Locally pressed photonic crystal fiber interferometer for multiparameter sensing.  

Science.gov (United States)

A mode interferometer consisting of a short section of photonic crystal fiber (PCF) fusion spliced to a standard single-mode optical fiber with localized perturbations is proposed for multiparameter sensing. In this sensing configuration, the parameter being sensed changes the visibility (an absolute parameter) of the interference pattern and also causes a shift (a relative parameter) to the interference pattern. To achieve this dual effect, a portion of the PCF is squeezed on localized regions with a serrated mechanical piece. In this manner, we introduce attenuation losses and effective refractive index changes to the interfering modes, hence, visibility changes and a shift to the interference pattern. Our device is suitable for monitoring diverse physical parameters, such as weight, lateral force, pressure, load, etc., with the advantage that compensation to temperature or power fluctuations is not required. Moreover, the sensor sensitivity can be adjusted in a simple manner. PMID:24784050

Villatoro, Joel; Minkovich, Vladimir P; Zubia, Joseba

2014-05-01

324

Microfabrication of fiber optic scanners  

Science.gov (United States)

A cantilevered optical fiber is micromachined to function as a miniature resonant opto-mechanical scanner. By driving the base of the cantilevered fiber at a resonance frequency using a piezoelectric actuator, the free end of the cantilever beam becomes a scanned light source. The fiber scanners are designed to achieve wide field-of-view (FOV) and high scan frequency. We employ a non-linearly tapered profile fiber to achieve scan amplitudes of 1 mm at scan frequencies above 20 KHz. Scan angles of over 120 degree(s) (full angle) have been achieved. Higher order modes are also employed for scanning applications that require compactness while maintaining large angular FOV. Etching techniques are used to create the non-linearly tapered sections in single mode optical fiber. Additionally, micro-lenses are fabricated on the tips of the etched fibers, with lens diameters as small as 15 microns. Such lenses are capable of reducing the divergence angle of the emitted light to 5 degree(s) (full angle), with greater reduction expected by employing novel lens shaping techniques. Microfabricated optical fiber scanners have display applications ranging from micro-optical displays to larger panoramic displays. Applications for micro-image acquisition include small barcode readers to medical endoscopes.

Fauver, Mark; Crossman-Bosworth, Janet L.; Seibel, Eric J.

2002-06-01

325

Fiber-Optic Distribution Of Pulsed Power To Multiple Sensors  

Science.gov (United States)

Optoelectronic systems designed according to time-sharing scheme distribute optical power to multiple integrated-circuit-based sensors in fiber-optic networks. Networks combine flexibility of electronic sensing circuits with advantage of electrical isolation afforded by use of optical fibers instead of electrical conductors to transmit both signals and power. Fiber optics resist corrosion and immune to electromagnetic interference. Sensor networks of this type useful in variety of applications; for example, in monitoring strains in aircraft, buildings, and bridges, and in monitoring and controlling shapes of flexible structures.

Kirkham, Harold

1996-01-01

326

Towards biochips using microstructured optical fiber sensors  

DEFF Research Database (Denmark)

In this paper we present the first incorporation of a microstructured optical fiber (MOF) into biochip applications. A 16-mm-long piece of MOF is incorporated into an optic-fluidic coupler chip, which is fabricated in PMMA polymer using a CO2 laser. The developed chip configuration allows the continuous control of liquid flow through the MOF and simultaneous optical characterization. While integrated in the chip, the MOF is functionalized towards the capture of a specific single-stranded DNA string by immobilizing a sensing layer on the microstructured internal surfaces of the fiber. The sensing layer contains the DNA string complementary to the target DNA sequence and thus operates through the highly selective DNA hybridization process. Optical detection of the captured DNA was carried out using the evanescent-wave-sensing principle. Owing to the small size of the chip, the presented technique allows for analysis of sample volumes down to 300 nL and the fabrication of miniaturized portable devices.

Rindorf, Lars Henning; Hoiby, Poul Erik

2006-01-01

327

Implementation of a High-Speed FPGA and DSP Based FFT Processor for Improving Strain Demodulation Performance in a Fiber-Optic-Based Sensing System  

Science.gov (United States)

NASA's Aviation Safety and Security Program is pursuing research in on-board Structural Health Management (SHM) technologies for purposes of reducing or eliminating aircraft accidents due to system and component failures. Under this program, NASA Langley Research Center (LaRC) is developing a strain-based structural health-monitoring concept that incorporates a fiber optic-based measuring system for acquiring strain values. This fiber optic-based measuring system provides for the distribution of thousands of strain sensors embedded in a network of fiber optic cables. The resolution of strain value at each discrete sensor point requires a computationally demanding data reduction software process that, when hosted on a conventional processor, is not suitable for near real-time measurement. This report describes the development and integration of an alternative computing environment using dedicated computing hardware for performing the data reduction. Performance comparison between the existing and the hardware-based system is presented.

Farley, Douglas L.

2005-01-01

328

Achromatic optical diode in fiber optics  

CERN Document Server

We propose a broadband optical diode, which is composed of one achromatic reciprocal quarter-wave plate and one non-reciprocal quarter-wave plate, both placed between two crossed polarizers. The presented design of achromatic wave plates relies on an adiabatic evolution of the Stokes vector, thus, the scheme is robust and efficient. The possible simple implementation using fiber optics is suggested.

Berent, Michal; Vitanov, Nikolay V

2013-01-01

329

Fiber optic fire detection technology  

International Nuclear Information System (INIS)

Electrostatic application of paint was, and still is, the most technically feasible method of reducing VOC (volatile organic compounds) emissions, while reducing the cost to apply the coatings. Prior to the use of electrostatics, only two sides of the traditional fire triangle were normally present in the booth, fuel (solvent), and oxygen (air). Now the third leg (the ignition source) was present at virtually all times during the production operation in the form of the electrostatic charge and the resulting energy in the system. The introduction of fiber optics into the field of fire detection was for specific application to the electrostatic painting industry, but specifically, robots used in the application of electrostatic painting in the automotive industry. The use of fiber optics in this hazard provided detection for locations that have been previously prohibited or inaccessible with the traditional fire detection systems. The fiber optic technology that has been adapted to the field of fire detection operates on the principle of transmission of photons through a light guide (optic fiber). When the light guide is subjected to heat, the cladding on the light guide melts away from the core and allows the light (photons) to escape. The controller, which contains the emitter and receiver is set-up to distinguish between partial loss of light and a total loss of light. Glass optical fibers carrying light offer distinct advantages over wires or coaxial cables carryingages over wires or coaxial cables carrying electricity as a transmission media. The uses of fiber optic detection will be expanded in the near future into such areas as aircraft, cable trays and long conveyor runs because fiber optics can carry more information and deliver it with greater clarity over longer distances with total immunity to all kinds of electrical interference

330

Te-based glass fiber for far-infrared biochemical sensing up to 16 ?m.  

Science.gov (United States)

Chalcogenide glass fibers are very suitable to carry out mid-infrared spectroscopy by Fiber Evanescent Wave Spectroscopy (FEWS). Nowadays, selenide glasses are used for FEWS, but the reachable domain is limited in the infrared to typically 12 µm. Te-rich glasses, due to their heavy atomic weight, are better for far-infrared sensing but they crystallize easily and until now that was difficult to prepare operational optical fibers from such glasses. In this work, Te-Ge-AgI highly purified glasses have been prepared and successfully drawn into optical fiber. The minimum of attenuation is 3 dB/m around 10 ?m, which is up to now the lowest value ever measured for Te-based fiber. Overall, such fibers open the sensing window up to 16 ?m against 12 µm so far. Then, for the first time, tapered telluride fibers with different diameters at the sensing zone were obtained during the fiber drawing process. Chloroform and butter were used to test the fiber infrared sensing ability, and the sensitivity has been greatly enhanced as the sensing zone fiber diameter decreases. Finally, the new protocol of telluride glass preparation allows shaping them into efficient functional fibers, opening further in the mid-infrared which is essential for chemical spectroscopy. PMID:25321505

Cui, Shuo; Boussard-Plédel, Catherine; Lucas, Jacques; Bureau, Bruno

2014-09-01

331

Laser-Pulse/Fiber-Optic Liquid-Leak Detector  

Science.gov (United States)

Several potential leak sites monitored using single sensing fiber. Fluid systems monitored quickly for leaks in remote, hazardous, or inaccessible locations by system of compact, lightweight fiber-optic leak sensors presently undergoing development. Sensors installed at potential leak sites as joints, couplings, and fittings. Sensor read by sending laser pulse along fiber, then noting presence or relative amplitude of return pulse. Leak-monitoring technique applicable to wide range of fluid systems and minimizes human exposure to toxic or dangerous fluids.

Padgett, M. E.

1986-01-01

332

A Novel Design of Grooved Fibers for Fiber-Optic Localized Plasmon Resonance Biosensors  

Directory of Open Access Journals (Sweden)

Full Text Available Bio-molecular recognition is detected by the unique optical properties of self-assembled gold nanoparticles on the unclad portions of an optical fiber whose surfaces have been modified with a receptor. To enhance the performance of the sensing platform, the sensing element is integrated with a microfluidic chip to reduce sample and reagent volume, to shorten response time and analysis time, as well as to increase sensitivity. The main purpose of the present study is to design grooves on the optical fiber for the FO-LPR microfluidic chip and investigate the effect of the groove geometry on the biochemical binding kinetics through simulations. The optical fiber is designed and termed as U-type or D-type based on the shape of the grooves. The numerical results indicate that the design of the D-type fiber exhibits efficient performance on biochemical binding. The grooves designed on the optical fiber also induce chaotic advection to enhance the mixing in the microchannel. The mixing patterns indicate that D-type grooves enhance the mixing more effectively than U-type grooves. D-type fiber with six grooves is the optimum design according to the numerical results. The experimental results show that the D-type fiber could sustain larger elongation than the U-type fiber. Furthermore, this study successfully demonstrates the feasibility of fabricating the grooved optical fibers by the femtosecond laser, and making a transmission-based FO-LPR probe for chemical sensing. The sensor resolution of the sensor implementing the D-type fiber modified by gold nanoparticles was 4.1 × 10-7 RIU, which is much more sensitive than that of U-type optical fiber (1.8 × 10-3 RIU.

Lai-Kwan Chau

2009-08-01

333

Development of random hole optical fiber and crucible technique optical fibers  

Science.gov (United States)

This dissertation reports the development of two new categories of optical fibers. These are the Random Hole Optical Fiber (RHOF) and the Crucible Technique Hybrid Fiber (CTF). The RHOF is a new class of microstructure fiber which possesses air holes which vary in diameter and location along the length of the fiber. Unlike all prior microstructure fibers, these RHOF do not have continuous air holes which extend throughout the fiber. The CTF is a method for incorporating glasses with vastly differing thermal properties into a single optical fiber. Each of these two classes of fiber brings a new set of optical characteristics into being. The RHOF exhibit many of the same guidance properties as the previously researched microstructure fibers, such as reduced mode counts in a large area core. CTF fibers show great promise for integrating core materials with extremely high levels of nonlinearity or gain. The initial goal of this work was to combine the two techniques to form a fiber with exceedingly high efficiency of nonlinear interactions. Numerous methods have been endeavored in the attempt to achieve the fabrication of the RHOF. Some of the methods include the use of sol-gel glass, microbubbles, various silica powders, and silica powders with the incorporation of gas producing agents. Through careful balancing of the competing forces of surface tension and internal pressure it has been possible to produce an optical fiber which guides light successfully. The optical loss of these fibers depends strongly on the geometrical arrangement of the air holes. Fibers with a higher number of smaller holes possess a markedly lower attenuation. RHOF also possess, to at least some degree the reduced mode number which has been extensively reported in the past for ordered hole fibers. Remarkably, the RHOF are also inherently pressure sensitive. When force is applied to an RHOF either isotropically, or on an axis perpendicular to the length of the fiber, a wavelength dependent loss is observed. This loss does not come with a corresponding response to temperature, rendering the RHOF highly anomalous in the area of fiber optic sensing techniques. Furthermore an ordered hole fiber was also tested to determine that this was not merely a hitherto undisclosed property of all microstructure fibers. Crucible technique fibers have also been fabricated by constructing an extremely thick walled silica tube, which is sealed at the bottom. A piece of the glass that is desired for the core (such as Lead Indium Phosphate) is inserted into the hole which is in the center of the tube. The preform is then drawn on an fiber draw tower, resulting in a fiber with a core consisting of a material which has a coefficient of thermal expansion (CTE) or a melting temperature (Tm) which is not commonly compatible with those of silica.

Kominsky, Daniel

334

A fiber-optic current sensor for aerospace applications  

International Nuclear Information System (INIS)

A robust, accurate, broad-band, alternating current sensor using fiber optics is being developed for space applications at power frequencies as high as 20 kHz. It can also be used in low and high voltage 60 Hz terrestrial power systems and in 400 Hz aircraft systems. It is intrinsically EMI immune and has the added benefit of excellent isolation. The sensor uses the Faraday effect in optical fiber and standard polarimetric measurements to sense electrical current. The primary component of the sensor is a specially treated coil of single-mode optical fiber, through which the current carrying conductor passes. Improved precision is accomplished by temperature compensation by means of signals from a novel fiber-optic temperature sensor embedded in the sensing head. This paper reports on the technology contained in the sensor and also relates the results of precision tests conducted at various temperatures within the wide operating range. It also shows the results of early EMI tests

335

Multimode optical fiber based spectrometers  

CERN Document Server

A standard multimode optical fiber can be used as a general purpose spectrometer after calibrating the wavelength dependent speckle patterns produced by interference between the guided modes of the fiber. A transmission matrix was used to store the calibration data and a robust algorithm was developed to reconstruct an arbitrary input spectrum in the presence of experimental noise. We demonstrate that a 20 meter long fiber can resolve two laser lines separated by only 8 pm. At the other extreme, we show that a 2 centimeter long fiber can measure a broadband continuous spectrum generated from a supercontinuum source. We investigate the effect of the fiber geometry on the spectral resolution and bandwidth, and also discuss the additional limitation on the bandwidth imposed by speckle contrast reduction when measuring dense spectra. Finally, we demonstrate a method to reduce the spectrum reconstruction error and increase the bandwidth by separately imaging the speckle patterns of orthogonal polarizations. The mu...

Redding, Brandon; Cao, Hui

2013-01-01

336

Optical fibres for optical sensing.  

Czech Academy of Sciences Publication Activity Database

Pecs : University of Pecs, 2006, s. 89-91. - (ASCOS Series). [ASCOS 2006 /5./. Tihany (HU), 03.09.2006-09.09.2006] R&D Projects: GA ?R(CZ) GA102/05/0948; GA MŠk(CZ) LC06034 Institutional research plan: CEZ:AV0Z20670512 Keywords : optical fibres * optical sensors Subject RIV: JB - Sensors, Measurment, Regulation

Kašík, Ivan; Mat?jec, Vlastimil; Chomát, Miroslav; Berková, Daniela; Hayer, Miloš; Mrázek, Jan; Podrazký, Ond?ej

337

Modeling Climate Change and Thermal Restoration Strategies in a Northern California Stream Using HEAT SOURCE and Distributed Temperature Sensing Fiber-optics  

Science.gov (United States)

Land uses which modify stream channel structure and riparian vegetation can alter the mechanisms of heat transfer within a stream. Stream temperature is a crucial abiotic factor which governs aquatic biota quantity, distribution, and overall health. The IPCC has projected stream temperature to increase with changes in global climate due to elevated air temperature and changes in precipitation patterns. Stream temperature modeling can investigate current and future stream temperature conditions. Heat Source, developed by Oregon Department of Environmental Quality (DEQ), was applied to a one kilometer section of the North Fork of the Salmon River, a tributary of the Klamath River, northern California, USA. Heat Source accounts for internal and external thermal energy transfers to predict stream temperature at point locations. Inputs include meteorologic, geomorphologic, hydrologic and topographic measurements from the study site. The Salmon River watershed has a legacy of historic hydraulic gold mining which has changed channel morphology and created extensive denuded gravel bars. The Salmon River is listed as thermally impaired under California's List of Impaired Water Bodies 303(d) with mainstem temperature commonly exceeding salmonid temperature thresholds. The objective of this research was to utilize Heat Source to predict effects of climate change, riparian management, and channel geometry on stream temperature. This study employed Distributed Temperature Sensing fiber-optics (DTS) to detect stream heating and cooling at one meter resolution which was then used to calibrate Heat Source at the study reach. Predicted values closely matched DTS measurements reflecting shifting responses to air temperature, riparian vegetation distribution, and channel geometry conditions. Heat Source modeling of climate change scenarios using forecasted 2049 and 2099 elevated air temperatures are presented. Furthermore, temperature impacts of increased riparian vegetation density and stream channelization were investigated as possible thermal restoration strategies to buffer streams from elevated temperatures resulting from climate change.

Bond, R. M.; Stubblefield, A. P.

2013-12-01

338

Optical Fiber Embedded in Epoxy Glass Unidirectional Fiber Composite System  

OpenAIRE

We aimed to embed silica optical fibers in composites (epoxy vinyl ester matrix reinforced with E-glass unidirectional fibers in mass fraction of 60%) in order to further monitor the robustness of civil engineering structures (such as bridges). A simple system was implemented using two different silica optical fibers (F1—double coating of 172 µm diameter and F2—single coating of 101.8 µm diameter respectively). The optical fibers were dynamically tensile tested and Weibull plots were tr...

Irina Severin; Rochdi El Abdi; Guillaume Corvec; Mihai Caramihai

2013-01-01

339

Optical fiber beam loss monitor  

International Nuclear Information System (INIS)

We have been developed an arc sensor with high sensitivity since 2007. When the arc sensor was installed into the cavity coupler located in the beam tunnel, it is found that an arc sensor reacted to beam loss sensitively. This is because Cherenkov light occurs in the optical fiber by the charged particle. This means that the state of the beam loss can be detected by observing the Cherenkov light. Large-diameter optical fibers were set into the acceleration structures and vacuum ducts. We observed light from an optical fiber by the photo-multiplier tube (PMT). When we observed light from the upstream, we can identify the point of the beam loss in position resolution of 8.3 nsec/m. We observed beam loss at various points of the Linac. (author)

340

Measurement of distributed strain and temperature in a branched optical fiber network by use of Brillouin optical time-domain reflectometry.  

Science.gov (United States)

A new scheme is proposed for sensing distributed strain and temperature in optical fibers. This scheme uses Brillouin scattering as the sensing mechanism and a branched optical fiber network as the sensing fibers. Brillouin optical time-domain reflectometry makes it possible to distinguish Brillouin-scattered light waves from different optical fiber branches in the network when the different Brillouin frequency shifts are assigned to each branch. The technical feasibility of this scheme is confirmed experimentally for a branched optical network composed of two branches connected to a trunk optical fiber. PMID:19859236

Shimizu, K; Horiguchi, T; Koyamada, Y

1995-03-01

341

Fiber optic interferometer with digital heterodyne detection using lithiumniobate devices  

International Nuclear Information System (INIS)

Fiber optic interferometers with single mode fibers provide high sensitivity for sensing e.g. temperature, sound, electric and magnetic fields. The inclusion of integrated optic components into the interferometer implements important functions such as splitting, recombining, phase compensation, polarization control in a compact way. Above all, integrated optic devices allow efficient heterodyne detection schemes with a linear conversion of the sensor phase ? and the sensor transmission H into corresponding electrical signals. electro-optic LiNbO3 devices are particularly attractive for these purposes. Here, the authors report on fiber optic Michelson and Mach-Zehnder interferometers which are built-up with polarization maintaining fibers and integrated optic LiNbO3 devices. A digital heterodyne detection with a high dynamic range (up to 60 dB) is accomplished by a proper digital phase modulation. A basic configuration is depicted

342

Fiber optics principles and practices  

CERN Document Server

Since the invention of the laser, our fascination with the photon has led to one of the most dynamic and rapidly growing fields of technology. New advances in fiber optic devices, components, and materials make it more important than ever to stay current. Comprising chapters drawn from the author's highly anticipated book Photonics: Principles and Practices, Fiber Optics: Principles and Practices offers a detailed and focused treatment for anyone in need of authoritative information on this critical area underlying photonics.Using a consistent approach, the author leads you step-by-step throug

Al-Azzawi, Abdul

2007-01-01

343

Fundamental Study on the Development of Fiber Optic Sensor for Real-time Sensing of CaCO3 Scale Formation in Geothermal Water.  

Science.gov (United States)

This study proposes an optical fiber sensor for calcium carbonate (CaCO3) scale formation in water. The sensor is easily fabricated by removing the cladding of a multimode fiber to expose the core towards the surrounding medium in order to detect refractive index change. A variation of the transmittance response from the high refractive index of CaCO3 which precipitated on the fiber core surface was observed. The proposed setup can be used to analyze the transmittance response over wide range of wavelength using white light as a source and also a spectroscopy detector. The curve of the transmittance percentage over time showed that a fiber core with 200 ?m has higher sensitivity as compared to a fiber core with 400 ?m. The findings from this study showed that the sensor detection region at near infrared (NIR) wavelengths showed better sensitivity than visible light (VIS) wavelengths. Field tests were conducted using natural geothermal water at Matsushiro, Japan in order to verify the performance of the proposed sensor. The optical response was successfully evaluated and the analytical results confirmed the capability of monitoring scale formation in a geothermal water environment. PMID:25765379

Okazaki, Takuya; Imai, Kenichiro; Tan, Shin Y; Yong, Yun T; Rahman, Faidz A; Hata, Noriko; Taguchi, Shigeru; Ueda, Akira; Kuramitz, Hideki

2015-01-01

344

Fiber-Optic Continuous Liquid Sensor for Cryogenic Propellant Gauging  

Science.gov (United States)

An innovative fiber-optic sensor has been developed for low-thrust-level settled mass gauging with measurement uncertainty optical fiber to measure liquid level and liquid distribution of cryogenic propellants. Every point of the sensing fiber is a point sensor that not only distinguishes liquid and vapor, but also measures temperature. This sensor is able to determine the physical location of each point sensor with 1-mm spatial resolution. Acting as a continuous array of numerous liquid/vapor point sensors, the truly distributed optical sensing fiber can be installed in a propellant tank in the same manner as silicon diode point sensor stripes using only a single feedthrough to connect to an optical signal interrogation unit outside the tank. Either water or liquid nitrogen levels can be measured within 1-mm spatial resolution up to a distance of 70 meters from the optical interrogation unit. This liquid-level sensing technique was also compared to the pressure gauge measurement technique in water and liquid nitrogen contained in a vertical copper pipe with a reasonable degree of accuracy. It has been demonstrated that the sensor can measure liquid levels in multiple containers containing water or liquid nitrogen with one signal interrogation unit. The liquid levels measured by the multiple fiber sensors were consistent with those virtually measured by a ruler. The sensing performance of various optical fibers has been measured, and has demonstrated that they can survive after immersion at cryogenic temperatures. The fiber strength in liquid nitrogen has also been measured. Multiple water level tests were also conducted under various actual and theoretical vibration conditions, and demonstrated that the signal-to-noise ratio under these vibration conditions, insofar as it affects measurement accuracy, is manageable and robust enough for a wide variety of spacecraft applications. A simple solution has been developed to absorb optical energy at the termination of the optical sensor, thereby avoiding any feedback to the optical interrogation unit

Xu. Wei

2010-01-01

345

Recent progress in distributed fiber optic sensors.  

Science.gov (United States)

Rayleigh, Brillouin and Raman scatterings in fibers result from the interaction of photons with local material characteristic features like density, temperature and strain. For example an acoustic/mechanical wave generates a dynamic density variation; such a variation may be affected by local temperature, strain, vibration and birefringence. By detecting changes in the amplitude, frequency and phase of light scattered along a fiber, one can realize a distributed fiber sensor for measuring localized temperature, strain, vibration and birefringence over lengths ranging from meters to one hundred kilometers. Such a measurement can be made in the time domain or frequency domain to resolve location information. With coherent detection of the scattered light one can observe changes in birefringence and beat length for fibers and devices. The progress on state of the art technology for sensing performance, in terms of spatial resolution and limitations on sensing length is reviewed. These distributed sensors can be used for disaster prevention in the civil structural monitoring of pipelines, bridges, dams and railroads. A sensor with centimeter spatial resolution and high precision measurement of temperature, strain, vibration and birefringence can find applications in aerospace smart structures, material processing, and the characterization of optical materials and devices. PMID:23012508

Bao, Xiaoyi; Chen, Liang

2012-01-01

346

Recent Progress in Distributed Fiber Optic Sensors  

Directory of Open Access Journals (Sweden)

Full Text Available Rayleigh, Brillouin and Raman scatterings in fibers result from the interaction of photons with local material characteristic features like density, temperature and strain. For example an acoustic/mechanical wave generates a dynamic density variation; such a variation may be affected by local temperature, strain, vibration and birefringence. By detecting changes in the amplitude, frequency and phase of light scattered along a fiber, one can realize a distributed fiber sensor for measuring localized temperature, strain, vibration and birefringence over lengths ranging from meters to one hundred kilometers. Such a measurement can be made in the time domain or frequency domain to resolve location information. With coherent detection of the scattered light one can observe changes in birefringence and beat length for fibers and devices. The progress on state of the art technology for sensing performance, in terms of spatial resolution and limitations on sensing length is reviewed. These distributed sensors can be used for disaster prevention in the civil structural monitoring of pipelines, bridges, dams and railroads. A sensor with centimeter spatial resolution and high precision measurement of temperature, strain, vibration and birefringence can find applications in aerospace smart structures, material processing, and the characterization of optical materials and devices.

Xiaoyi Bao

2012-06-01

347

A fiber-optic hydrophone with an acoustic filter  

Science.gov (United States)

A novel Michelson interferometric fiber-optic hydrophone with a mechanical anti-aliasing acoustic filter, which consists of a two-hole cylindrical Helmholtz resonator, has been manufactured and tested. Experimental results show that this new fiber-optic hydrophone has a function of acoustic low-pass filtering. The low frequency sensitivity, as determined by the fiber interferometer and the sensing mandrel, is about -159dB re 1rad/?Pa. The frequency response has a break point near 1200Hz and a measured roll-off of 50dB/octave. The fiber-optic hydrophone is a prototype device for a class of sensors that used to eliminate aliasing in the future sonar systems. To our knowledge, this is the first time that such a fiber-optic hydrophone has been reported.

Wang, Zefeng; Hu, Yongming; Meng, Zhou; Ni, Ming; Luo, Hong

2007-11-01

348

Embedded fiber optic sensors for structural damage detection  

Science.gov (United States)

A fiber optic optical time domain reflectometer-based (OTDR) sensing system is described for detecting the extent and/or location of damage incurred by a composite material following an impact event. Two multi-mode fibers are embedded within a graphite composite to form a 'checkerboard' fiber mesh with 0.5 inch spacing. The measurement system consists of a PC- based virtual instrument, a high resolution optical time domain reflectometer, and two fiber optic sensors. Using the OTDR and processing algorithms, the location of impact can be determined within the composite panel by scanning the length of each fiber from both ends. The OTDR scanning process yields four reference points which can be used to determine the location of the impact referenced to a coordinate axes designated within the composite panel.

Grace, Jennifer L.; Poland, Stephen H.; Murphy, Kent A.; Claus, Richard O.; Abraham, P.; Sridharan, K.

1996-05-01

349

High-performance hybrid Raman/fiber Bragg grating fiber-optic sensor based on simplex cyclic pulse coding.  

Science.gov (United States)

We propose and experimentally demonstrate the use of cyclic pulse coding to improve the performance of hybrid Raman/fiber Bragg grating (FBG) fiber-optic sensors, for simultaneous measurement of distributed static temperature and discrete dynamic strain over the same sensing fiber. Effective noise reduction is achieved in both Raman optical time-domain reflectometry and dynamic interrogation of time-division-multiplexed fiber FBG sensors, enhancing the sensing range resolution and providing real-time point dynamic strain measurement capabilities. The highly integrated sensor scheme employs broadband apodized low-reflectivity FBGs, a single narrowband optical source, and a shared receiver block. PMID:23455106

Taki, M; Zaidi, F; Toccafondo, I; Nannipieri, T; Signorini, A; Faralli, S; Di Pasquale, F

2013-02-15

350

Feasibility of giant fiber-optic gyroscopes  

OpenAIRE

The availability of long-distance, underground fiber-optic links opens a perspective of implementing interferometric fiber-optic gyroscopes embracing very large areas. We discuss the potential sensitivity, some disturbances and approaches to overcome them.

Schiller, Stephan

2013-01-01

351

Optically powered fiber networks  

OpenAIRE

Optically powered networks are demonstrated. Heterogeneous subscribers having widely varying needs with respect to power and bandwidth can be effectively controlled and optically supplied by a central office. The success of the scheme relies both on power-efficient innovative hardware and on a novel low-energy medium access control protocol. We demonstrate a sensor network with subscribers consuming less than 1 mu W average power, and an optically powered high-speed video link transmitting da...

Roger, M.; Bo?ttger, G.; Dreschmann, M.; Klamouris, C.; Hu?bner, M.; Bett, A. W.; Becker, J.; Freude, W.; Leuthold, J.

2008-01-01

352

Fiber optic probes for biomedical optical spectroscopy  

OpenAIRE

Optical spectroscopy has been well validated by the physical sciences as a method to characterize chemical compositions in biological material. It has also showed promising to detect atherosclerotic plaques, which can form in the coronary artery walls, and cause heart attacks and strokes. This project seeks to optimize and build fiber optic probes for diffuse reflectance and fluorescence spectroscopy which can assess these plaques. A side-viewing probe is particularly advantageous in t...

Bru, Jørgen

2008-01-01

353

Fiber-optical microphones and accelerometers based on polymer optical fiber Bragg gratings : [invited  

DEFF Research Database (Denmark)

Polymer optical fibers (POFs) are ideal for applications as the sensing element in fiber-optical microphones and accelerometers based on fiber Bragg gratings (FBGs) due to their reduced Young’s Modulus of 3.2GPa, compared to 72GPa of Silica. To maximize the sensitivity and the dynamic range of the device the outer diameter and the length of the sensing fiber segment should be as small as possible. To this end we have fabricated 3mm FBGs in single-mode step-index POFs of diameter 115 micron, using 325nm UV writing and a phase-mask technique. 6mm POF sections with FBGs in the center have been glued to standard Silica SMF28 fibers. These POF FBGs have been characterized in terms of temperature and strain to find operating regimes with no hysteresis. Commercial fast wavelength interrogators (KHz) are shown to be able to track the thin POF FBGs and they are finally applied in a prototype accelerometer. The specs are compared to the specs obtained when using Silica FBGs.

Yuan, Scott Wu Technical University of Denmark,

2010-01-01

354

Selective Serial Multi-Antibody Biosensing with TOPAS Microstructured Polymer Optical Fibers  

DEFF Research Database (Denmark)

We have developed a fluorescence-based fiber-optical biosensor, which can selectively detect different antibodies in serial at preselected positions inside a single piece of fiber. The fiber is a microstructured polymer optical fiber fabricated from TOPAS cyclic olefin copolymer, which allows for UV activation of localized sensor layers inside the holes of the fiber. Serial fluorescence-based selective sensing of Cy3-labelled ?-streptavidin and Cy5-labelled ?-CRP antibodies is demonstrated.

Emiliyanov, Grigoriy Andreev; HØiby, Poul E.

2013-01-01

355

An Integrated Photoluminescence Sensing Platform Using a Single-Multi-Mode Fiber Coupler-Based Probe  

OpenAIRE

We demonstrate an integrated fiber optic photoluminescence sensing platform using a novel single-multi-mode fiber coupler (SMFC)-based probe with high collection efficiency for fluorescence signals. The SMFC, prepared using fused biconical taper technology, not only transmits excitation light, but also collects and transmits fluorescence. The entire system does not use complex optical components and rarely requires optical alignment. The simple structure of the SMFC considerably improves the ...

Feng Long; Anna Zhu; Hanchang Shi

2014-01-01

356

Anisotropic Metamaterial Optical Fibers  

OpenAIRE

Internal physical structure can drastically modify the properties of waveguides: photonic crystal fibers are able to confine light inside a hollow air core by Bragg scattering from a periodic array of holes, while metamaterial loaded waveguides for microwaves can support propagation at frequencies well below cutoff. Anisotropic metamaterials assembled into cylindrically symmetric geometries constitute light-guiding structures that support new kinds of exotic modes. A microtu...

Pratap, Dheeraj; Ramakrishna, S. Anantha; Pollock, Justin G.; Iyer, Ashwin K.

2014-01-01

357

Applications of fiber optics in physical protection  

International Nuclear Information System (INIS)

The purpose of this NUREG is to provide technical information useful for the development of fiber-optic communications and intrusion detection subsystems relevant to physical protection. There are major sections on fiber-optic technology and applications. Other topics include fiber-optic system components and systems engineering. This document also contains a glossary, a list of standards and specifications, and a list of fiber-optic equipment vendors

358

High pressure fiber optic sensor system  

Science.gov (United States)

The present application provides a fiber optic sensor system. The fiber optic sensor system may include a small diameter bellows, a large diameter bellows, and a fiber optic pressure sensor attached to the small diameter bellows. Contraction of the large diameter bellows under an applied pressure may cause the small diameter bellows to expand such that the fiber optic pressure sensor may measure the applied pressure.

Guida, Renato; Xia, Hua; Lee, Boon K; Dekate, Sachin N

2013-11-26

359

Applications of fiber optics in physical protection  

Energy Technology Data Exchange (ETDEWEB)

The purpose of this NUREG is to provide technical information useful for the development of fiber-optic communications and intrusion detection subsystems relevant to physical protection. There are major sections on fiber-optic technology and applications. Other topics include fiber-optic system components and systems engineering. This document also contains a glossary, a list of standards and specifications, and a list of fiber-optic equipment vendors.

Buckle, T.H. [Sandia National Labs., Albuquerque, NM (United States)

1994-03-01

360

Laser and Fiber Optics Student Resources  

Science.gov (United States)

This page from Laser-Tec, the Laser and Fiber Optics Regional Center, contains resources for students considering a career in lasers and fiber optics. First, lasers and fiber optics are defined and example applications are listed. Next, a list of laser and fiber optics technician jobs is presented along with a short description of what tasks these jobs perform. Lastly, external links are provided to educational resources.

361

Interferometric fiber-optic bending / nano-displacement sensor using plastic dual-core fiber  

CERN Document Server

We demonstrate an interferometric fiber-optic bending/micro-displacement sensor based on a plastic dual-core fiber with one end coated with a silver mirror. The two fiber cores are first excited with the same laser beam, the light in each core is then back-reflected at the mirror-coated fiber-end, and, finally, the light from the two cores is made to interfere at the coupling end. Bending of the fiber leads to shifting interference fringes that can be interrogated with a slit and a single photodetector. We find experimentally that the resolution of our bending sensor is ~3x10-4 m-1 for sensing of bending curvature, as well as ~70 nm for sensing of displacement of the fiber tip. We demonstrate operation of our sensor using two examples. One is weighting of the individual micro-crystals of salt, while the other one is monitoring dynamics of isopropanol evaporation.

Qu, H; Skorobogatiy, M

2014-01-01

362

Interferometric fiber-optic bending/nano-displacement sensor using plastic dual-core fiber  

Science.gov (United States)

We demonstrate an interferometric fiber-optic bending/micro-displacement sensor based on a plastic dual-core fiber with one end coated with a silver mirror. The two fiber cores are first excited with the same laser beam, the light in each core is then back-reflected at the mirror-coated fiber-end, and, finally, the light from the two cores is made to interfere at the coupling end. Bending of the fiber leads to shifting interference fringes that can be interrogated with a slit and a single photodetector. We find experimentally that the resolution of our bending sensor is ~3x10-4 m-1 for sensing of bending curvature, as well as ~70 nm for sensing of displacement of the fiber tip. We demonstrate operation of our sensor using two examples. One is weighting of the individual micro-crystals of salt, while the other one is monitoring dynamics of isopropanol evaporation.

Qu, H.; Yan, G. F.; Skorobogatiy, M.

2014-08-01

363

Polydimethylsiloxane fibers for optical fiber sensor of displacement  

Science.gov (United States)

The paper describes the preparation of polydimethylsiloxane (PDMS) fiber integrated on the conventional optical fibers and their use for optical fiber displacement sensor. PDMS fiber was made of silicone elastomer Sylgard 184 (Dow Corning) by drawing from partially cured silicone. Optical fiber displacement sensor using PDMS fiber is based on the measurement of the local minimum of optical signal in visible spectral range generated by intermodal interference of circularly symmetric modes. Position of the local minimum in spectral range varies by stretching the PDMS fiber of 230 ?m in the wavelength range from 688 to 477 nm. In the stretched PDMS fiber is possible to determine the longitudinal displacement with an accuracy of approximately 1 micrometer.

Martincek, Ivan; Pudis, Dusan; Gaso, Peter

2013-09-01

364

FOA Lecture 1: Fiber Optics & Communications  

Science.gov (United States)

This is the first of a series of short lectures on fiber optics by Jim Hayes, president of the Fiber Optic Association. This lecture covers how fiber optics are used in various types of systems such as telecommunications, CATV, security and Smart Grid. Running time for the lecture is 12:21. Flash is required to view the video.

Hayes, Jim

365

Career Directions--Fiber Optic Installer  

Science.gov (United States)

Fiber-optic communication is a method of transmitting information from one place to another by sending pulses of light through an optical fiber that is roughly the diameter of a human hair. The light forms an electromagnetic carrier wave that is modulated to carry information. Each optical fiber is capable of carrying an enormous amount of…

Tech Directions, 2012

2012-01-01

366

Study on the creep properties of distributed optical fiber sensors  

Science.gov (United States)

In this paper, based on the distributed optical fiber strain sensing technology of pulse-pre-pump Brillouin Optical Time Domain Analysis (PPP-BOTDA), the creep properties of two types of optical fiber sensors, i.e. single mode optical fiber with jacket (Type-A) and optical fiber with UV resin coating (Type-B), were studied at different load (60g~600g) amplitudes. Experimental results show that there exists some creep for both types in initial loading period and tend to level off with time. But for Type-B, the strain variation is 5% of initial strain, and the stabilization time is about 48h, both of which are obviously smaller than those of Type-A. As a result, it is revealed that Type-B is characterized by a smaller creep, suitable for the long-term monitoring of infrastructures.

Song, Shiwei; Yang, Caiqian; Wu, Zhishen; Zhang, Yufeng; Shen, Sheng

2010-04-01

367

Optically powered fiber networks.  

Science.gov (United States)

Optically powered networks are demonstrated. Heterogeneous subscribers having widely varying needs with respect to power and band-width can be effectively controlled and optically supplied by a central of-fice. The success of the scheme relies both on power-efficient innovative hardware and on a novel low-energy medium access control protocol. We demonstrate a sensor network with subscribers consuming less than 1 microW average power, and an optically powered high-speed video link transmitting data at a bitrate of 100 Mbit/s. PMID:19104615

Röger, M; Böttger, G; Dreschmann, M; Klamouris, C; Huebner, M; Bett, A W; Becker, J; Freude, W; Leuthold, J

2008-12-22

368

Fiber optic and laser sensors IX; Proceedings of the Meeting, Boston, MA, Sept. 3-5, 1991  

Science.gov (United States)

The present volume on fiber-optic and laser sensors discusses industrial applications of fiber-optic sensors, fiber-optic temperature sensors, fiber-optic current sensors, fiber-optic pressure/displacement/vibration sensors, and generic fiber-optic systems. Attention is given to a fiber-sensor design for turbine engines, fiber-optic remote Fourier transform IR spectroscopy, near-IR fiber-optic temperature sensors, and an intensity-type fiber-optic electric current sensor. Topics addressed include fiber-optic magnetic field sensors based on the Faraday effect in new materials, diaphragm size and sensitivity for fiber-optic pressure sensors, a microbend pressure sensor for high-temperature environments, and linear position sensing by light exchange between two lossy waveguides. Also discussed are two-mode elliptical-core fiber sensors for measurement of strain and temperature, a fiber-optic interferometric X-ray dosimeter, fiber-optic interferometric sensors using multimode fibers, and optical fiber sensing of corona discharges.

Depaula, Ramon P. (editor); Udd, Eric (editor)

1991-01-01

369

Application of active heat pulse method with fiber optic temperature sensing for estimation of wetting bulbs and water distribution in drip emitters.  

OpenAIRE

Through the use of the Distributed Fiber Optic Temperature Measurement (DFOT) method, it is possible to measure the temperature in small intervals (on the order of centimeters) for long distances (on the order of kilometers) with a high temporal frequency and great accuracy. The heat pulse method consists of applying a known amount of heat to the soil and monitoring the temperature evolution, which is primarily dependent on the soil moisture content. The use of both methods, which is called t...

Gil Rodri?guez, Mari?a; Rodri?guez Sinobas, Leonor; Benitez Buelga, Javier; Sa?nchez Calvo, Rau?l

2013-01-01

370

Surface-bonded fiber optic Sagnac sensors for ultrasound detection.  

Science.gov (United States)

This paper describes a fiber optic sensor suitable for remote sensing and multi-point detection of ultrasound. This ultrasound sensor is based on the surface-bonded fiber optic Sagnac interferometer with the output fringe visibility of 1; it consists of a laser source, an ordinary single mode fiber delay line, a fiber coupler, a phase modulator and polarization controllers. For the validation of the sensor, surface acoustic waves and Lamb waves are excited by illuminating a steel specimen with an array of Q-switched Nd:YAG laser-generated line sources and the measurement of laser-generated ultrasonic waves are performed on the specimen surface using the surface-mounting fiber optic Sagnac sensor. The surface-bonded fiber optic sensor developed in this study has a simple configuration for detection of ultrasonic waves. Effectiveness of surface-bonded fiber optic Sagnac sensors for remote sensing of ultrasound and in situ monitoring of structures is investigated. The capability of multi-point detection of ultrasound by this Sagnac sensor is also discussed. PMID:15047393

Jang, Tae Seong; Lee, Seung Seok; Kim, Young Gil

2004-04-01

371

[94 km Brillouin distributed optical fiber sensors based on ultra-long fiber ring laser pumping].  

Science.gov (United States)

A novel optical amplification configuration based on ultra-long fiber laser with a ring cavity was proposed and applied to Brillouin optical time-domain analysis (BOTDA) sensing system, in order to extend the measurement distance significantly. The parameters used in the experiment were optimized, considering the main limitations of the setup, such as depletion, self-phase modulation (SPM) and pump-signal relative intensity noise (RIN) transfer. Through analyzing Brillouin gain spectrum, we demonstrated distributed sensing over 94 km of standard single-mode fiber with 3 meter spatial resolution and strain/temperature accuracy of 28 /1. 4 degree C. PMID:25095405

Yuan, Cheng-Xu; Wang, Zi-Nan; Jia, Xin-Hong; Li, Jin; Yan, Xiao-Dong; Cui, An-Bin

2014-05-01

372

Distributed fiber sensing using Brillouin echoes  

OpenAIRE

A simple physical description of the nonlinear optical interaction based on Brillouin echoes is presented. This technique makes potentially possible distributed Brillouin sensing down to centimeter spatial resolution while preserving the narrowband feature of the natural Brillouin gain spectrum. Experimental conditions for the generation of Brillouin echoes are described and demonstrations of distributed measurements using a 1 ns (10 cm) pulse are presented.

The?venaz, Luc; Foaleng, Stella M.

2008-01-01

373

Fiber optic ionizing radiation detector  

International Nuclear Information System (INIS)

Radiation detection can be done by various types of devices, such as Geiger counters, thermoluminescent detectors, and electric field sensors. This paper reports on a noel design for an ionizing radiation sensor using coiled optical fibers, which can be placed within or near a radioactive source. This design has several features that make it different from sensors proposed in the past. In order to evaluate this sensor, coiled fiber samples were placed inside metallic and metal-matrix composite cylinders to evaluate the sensitivity of the detector as well as the shielding effectiveness of the materials

374

Localized strain sensing with fiber Bragg-grating ring cavities.  

Science.gov (United States)

We report the theoretical description and the experimental demonstration of an optical resonator formed by inserting a Fiber Bragg Grating (FBG) in a closed fiber loop. The spectral characteristics of such a resonator strongly depend on the reflectivity of the FBG. In the wavelength region where the FBG reflectivity R is negligible, the system behaves like a conventional ring resonator. On the other hand, when R is not vanishing, a split-mode structure can be observed, associated to the degeneracy removal of two counterpropagating resonant modes. The magnitude of the mode splitting can be used to sense small variations of the FBG physical parameters, such as length, temperature or group index. An example of strain sensing with this setup is reported, showing that the mode splitting is sensitive to a mechanical strain applied to the FBG, while it is almost insensitive to a strain applied to any other point of the resonator. This peculiar feature allows to perform cavity-enhanced, local strain measurements with a reduced sensitivity to environmental perturbations, which represents an important improvement in the framework of the fiber-optic sensors. PMID:24514497

Campanella, C E; Giorgini, A; Avino, S; Malara, P; Zullo, R; Gagliardi, G; De Natale, P

2013-12-01

375

Laser and Fiber Optics Curriculum Resources  

Science.gov (United States)

This page from Laser-Tec, the Laser and Fiber Optics Regional Center, contains links to resources for educators to use in instruction on lasers and fiber optics. These include curriculum materials from OP-TEC, SPIE Hands-On Optics, Practical Optics & Photonics Education Tools, and Fiber U Online learning website. Additionally, Laser-Tec is developing a "compact and low-cost optics toolkit that will include laboratory manual and video demonstrations."

376

Acoustic fiber laser array architecture with reduced optical feedback limitations  

Science.gov (United States)

Many sensing applications would benefit of multiplexing a maximum number of Distributed FeedBack Fiber Lasers (DFB FLs) on the same optical fiber. However, in such configurations, some physical mechanisms may impact DFB FLs stable operation, limiting, for instance, the number of DFB FLs spliced on the same fiber and the distance between them. The aim of this experimental study is to investigate the impact of optical feedback on DFB FLs stability. The results of our study are used to propose possible associated architectures.

Molin, S.; Bouffaron, R.; Peigné, A.; Doisy, M.; Mugnier, A.; Pureur, D.

2014-05-01

377

Flexible Optical Waveguide Bent Loss Attenuation Effects Analysis and Modeling Application to an Intrinsic Optical Fiber Temperature Sensor  

Directory of Open Access Journals (Sweden)

Full Text Available The temperature dependence of the bending loss light energy in multimode optical fibers is reported and analyzed. The work described in this paper aims to extend an initial previous analysis concerning planar optical waveguides, light energy loss, to circular optical waveguides. The paper also presents à novel intrinsic fiber optic sensing device base on this study allowing to measure temperatures parameters. The simulation results are validated theoretically in the case of silica/silicone optical fiber. A comparison is done between results obtained with an optical fiber and the results obtained from the previous curved optical planar waveguide study. It is showed that the bending losses and the temperature measurement range depend on the curvature radius of an optical fiber or waveguide and the kind of the optical waveguide on which the sensing process is implemented.

Patrick Meyrueis

2012-03-01

378

High resolution underwater fiber optic threat detection system  

Science.gov (United States)

Current underwater protection systems are complex expensive devices consisting of multiple electronic sensing elements. The detection and identification of divers and small submerged watercraft requires very high image resolution. The high price of an array of conventional piezoelectric transducers and associated electronic components makes this solution feasible for localized implementations, but the protection of large stretches of coastline requires a different approach. We present a novel multichannel sonar design that augments current active sonar transducers with a passive fiber-optic multichannel acoustic emission sensing array. The system provides continuous monitoring of the acoustic wave reflections emitted by a single projector, yielding information about the size and shape of approaching objects. A novel fiber hydrophone enclosure is utilized to dramatically enhance the sensor response to the sonar frequency, while suppressing out-of-band sound sources and noise. The ability of a fiber hydrophone to respond to acoustic emissions is based on established fiber Bragg grating sensing techniques. In this approach, the energy of an acoustic wave is converted into the modulation of the in-fiber optical transducer's optical properties. The obtained results demonstrate significant response of the designed fiber optic hydrophone to the incident acoustic wave over the frequency domain from 1-80 kHz. Our approach allows selective tuning of the sensor to a particular acoustic frequency, as well as potential extension of the spectral response to 300- 400kHz.2

Berger, Alexander; Hermesh, Shalmon; Durets, Eugene; Kempen, Lothar U.

2006-10-01

379

FOA Lecture 4: Fiber Optic Cables  

Science.gov (United States)

This is the 4th lecture on fiber optics by Jim Hayes, president of the Fiber Optic Association. This lecture covers fiber optic cables. Cables are used to protect the fibers in the installation environment, outdoors or indoors. In this lecture, Hayes covers the requirements of cables for various applications and the types of cables typically used. Running time for the lecture is 10:15. Flash is required to view the video.

Hayes, Jim

380

A personal tour of the fiber optic Sagnac interferometer  

Science.gov (United States)

It has been over 30 years since the first fiber optic Sagnac interferometer was demonstrated by Vali and Shorthill in 1976 and the invention of the closed loop fiber optic gyro by Udd and Cahill in 1977. In these years the Sagnac interferometer in the form of the fiber optic gyro became and remains perhaps the most successful fiber optic sensor development. However it is not the only application of the fiber optic Sagnac interferometer and this paper is a personal tour of some other applications that include its usage for acoustic, strain, vibration, distributed sensing, intrusion detection and intrusion prevention. This paper is not intended to be a compressive review of the fiber optic Sagnac interferometer, instead it is a brief overview of a personal effort to develop fiber optic sensors and intrusion resistant communications systems based on this amazing interferometer with the help of friends at McDonnell Douglas, Blue Road Research, Columbia Gorge Research and a great deal of input from researchers worldwide.

Udd, Eric

2009-05-01

381

A fiber optic hybrid multifunctional AC voltage sensor  

Energy Technology Data Exchange (ETDEWEB)

Hybrid sensors have the advantages of both electronic and optical technologies. Their sensing element is based on conventional transducers and the optical fiber is used as a transmission media for the optical signal encoded with information between the local module and the remote module. The power supply for the remote module is usually provided by a built-in photoelectric converter illuminated by the optical radiation going through the same or another optical fiber. Electro-optic hybrid sensors have been widely used because of the electrical isolation provided by optical fiber. In the conventional fiber optic voltage sensor, piezoelectric or electro-optic transducers are implemented. Processing and conditioning measurement information is a complex task in these sensors. Moreover, the considerable drawback of most of these systems is that only one parameter, usually voltage value, is measured. This paper presented a novel fiber optic hybrid sensor for alternating current voltage measurements. This instrument provides the simultaneous measurement of four parameters, notably voltage value, frequency, phase angle and the external temperature. The paper described the measurement technology of the instrument including the remote module and optical powering as well as the unique modulation algorithm. The results and conclusions were also presented. 7 refs., 4 figs.

Sokolovsky, A.; Zadvornov, S. [IRE, Moscow (Russian Federation); Ryabko, M. [UFD, Moscow (Russian Federation)

2008-07-01

382

Active Optical Fibers Doped with Ceramic Nanocrystals  

Directory of Open Access Journals (Sweden)

Full Text Available Erbium-doped active optical fiber was successfully prepared by incorporation of ceramic nanocrystals inside a core of optical fiber. Modified chemical vapor deposition was combined with solution-doping approach to preparing preform. Instead of inorganic salts erbium-doped yttrium-aluminium garnet nanocrystals were used in the solution-doping process. Prepared preform was drawn into single-mode optical fiber with a numerical aperture 0.167. Optical and luminescence properties of the fiber were analyzed. Lasing ability of prepared fiber was proofed in a fiber-ring set-up. Optimal laser properties were achieved for a fiber length of 20~m. The slope efficiency of the fiber-laser was about 15%. Presented method can be simply extended to the deposition of other ceramic nanomaterials.

Jan Mrazek

2014-01-01

383

Gamma-rays and neutrons effects on optical fibers and Bragg gratings for temperature sensors  

OpenAIRE

The nuclear industry shows an increasing interest in the fiber optic technology for both data communication and sensing applications in nuclear plants. The optical fibers offer several advantages and the sensors based on this technology do not need any electrical power at the sensing point, they have a quick response and they can be easily multiplexed: in the case of a temperature sensor, several thermocouples can be substituted by a single fiber, resulting in a decrease of the waste material...

Morana, Adriana

2013-01-01

384

Chronology of Fabry-Perot Interferometer Fiber-Optic Sensors and Their Applications: A Review  

OpenAIRE

Optical fibers have been involved in the area of sensing applications for more than four decades. Moreover, interferometric optical fiber sensors have attracted broad interest for their prospective applications in sensing temperature, refractive index, strain measurement, pressure, acoustic wave, vibration, magnetic field, and voltage. During this time, numerous types of interferometers have been developed such as Fabry-Perot, Michelson, Mach-Zehnder, Sagnac Fiber, and Common-path interferome...

Md. Rajibul Islam; Muhammad Mahmood Ali; Man-Hong Lai; Kok-Sing Lim; Harith Ahmad

2014-01-01

385

Extending the sensing range of Brillouin optical time-domain analysis up to 325 km combining four optical repeaters  

OpenAIRE

A novel scheme is proposed to extend the sensing range of Brillouin optical time-domain analyzers (BOTDA). Specially-designed erbium doped fiber amplifier (EDFA) repeaters are located every 65km fiber along the sensing cable to achieve a total sensing length of 325km, corresponding to a 650km loop. At the end of the sensing fibre, we experimentally demonstrated a measurement repeatability of 2°C (2?) using a three meters spatial resolution.

Gyger, Flavien; Rochat, Etienne; Chin, Sanghoon; Nikle?s, Marc; The?venaz, Luc

2014-01-01

386

Extending the sensing range of Brillouin optical time-domain analysis up to 325 km combining four optical repeaters  

Science.gov (United States)

A novel scheme is proposed to extend the sensing range of Brillouin optical time-domain analyzers (BOTDA). Specially-designed erbium doped fiber amplifier (EDFA) repeaters are located every 65km fiber along the sensing cable to achieve a total sensing length of 325km, corresponding to a 650km loop. At the end of the sensing fibre, we experimentally demonstrated a measurement repeatability of 2°C (2?) using a three meters spatial resolution.

Gyger, F.; Rochat, E.; Chin, S.; Niklès, M.; Thévenaz, L.

2014-05-01

387

Fiber optic sensors II; Proceedings of the Meeting, The Hague, Netherlands, Mar. 31-Apr. 3, 1987  

International Nuclear Information System (INIS)

The present conference on fiber-optic sensors discusses topics in the state of development of distributed sensors, measurement techniques for pressure, vibration, and displacement, temperature measurements, signal processing and target detection techniques, chemical sensors, electrical machinery applications of fiber-optics, and novel fiber-optic components and devices. Attention is given to signal processing for enhanced optical time domain reflectometry, fiber-optic sensors based on resonating mechanical structures, photoacoustic oscillator sensors, a fiber-optic white light birefringent temperature sensor, a dual-wavelength approach to interferometric sensing, optical waveguide immunosensors, an evanescent wave fiber-optic sensor, a refractometer with inherent turbidity measurement, a fluorescence-based dissolved oxygen sensor, and a fiber-optic polarization-state controller

388

Distribution automation applications of fiber optics  

Science.gov (United States)

Motivations for interest and research in distribution automation are discussed. The communication requirements of distribution automation are examined and shown to exceed the capabilities of power line carrier, radio, and telephone systems. A fiber optic based communication system is described that is co-located with the distribution system and that could satisfy the data rate and reliability requirements. A cost comparison shows that it could be constructed at a cost that is similar to that of a power line carrier system. The requirements for fiber optic sensors for distribution automation are discussed. The design of a data link suitable for optically-powered electronic sensing is presented. Empirical results are given. A modeling technique that was used to understand the reflections of guided light from a variety of surfaces is described. An optical position-indicator design is discussed. Systems aspects of distribution automation are discussed, in particular, the lack of interface, communications, and data standards. The economics of distribution automation are examined.

Kirkham, Harold; Johnston, A.; Friend, H.

1989-01-01

389

Real-time In-Flight Strain and Deflection Monitoring with Fiber Optic Sensors  

Science.gov (United States)

This viewgraph presentation reviews Dryden's efforts to develop in-flight monitoring based on Fiber Optics. One of the motivating factors for this development was the breakup of the Helios aircraft. On Ikhana the use of fiber optics for wing shape sensing is being developed. They are being used to flight validate fiber optic sensor measurements and real-time wing shape sensing predictions on NASA's Ikhana vehicle; validate fiber optic mathematical models and design tools; Assess technical viability and, if applicable, develop methodology and approach to incorporate wing shape measurements within the vehicle flight control system, and develop and flight validate advanced approaches to perform active wing shape control.

Richards, Lance; Parker, Allen R.; Ko, William L.; Piazza, Anthony

2008-01-01

390

Fiber Optic Pressure Sensor using Multimode Interference  

Energy Technology Data Exchange (ETDEWEB)

Based on the theory of multimode interference (MMI) and self-image formation, we developed a novel intrinsic optical fiber pressure sensor. The sensing element consists of a section of multimode fiber (MMF) without cladding spliced between two single mode fibers (SMF). The MMI pressure sensor is based on the intensity changes that occur in the transmitted light when the effective refractive index of the MMF is changed. Basically, a thick layer of Polydimethylsiloxane (PDMS) is placed in direct contact with the MMF section, such that the contact area between the PDMS and the fiber will change proportionally with the applied pressure, which results in a variation of the transmitted light intensity. Using this configuration, a good correlation between the measured intensity variations and the applied pressure is obtained. The sensitivity of the sensor is 3 {mu}V/psi, for a range of 0-60 psi, and the maximum resolution of our system is 0.25 psi. Good repeatability is also observed with a standard deviation of 0.0019. The key feature of the proposed pressure sensor is its low fabrication cost, since the cost of the MMF is minimal.

Ruiz-Perez, V I; Sanchez-Mondragon, J J [INAOE, Apartado Postal 51 y 216, Puebla 72000 (Mexico); Basurto-Pensado, M A [CIICAp, Universidad Autonoma del Estado de Morelos (Mexico); LiKamWa, P [CREOL, University of Central Florida, Orlando, FL 32816 (United States); May-Arrioja, D A, E-mail: iruiz@inaoep.mx, E-mail: mbasurto@uaem.mx, E-mail: delta_dirac@hotmail.com, E-mail: daniel_may_arrioja@hotmail.com [UAT Reynosa Rodhe, Universidad Autonoma de Tamaulipas (Mexico)

2011-01-01

391

Fiber Optic Pressure Sensor using Multimode Interference  

Science.gov (United States)

Based on the theory of multimode interference (MMI) and self-image formation, we developed a novel intrinsic optical fiber pressure sensor. The sensing element consists of a section of multimode fiber (MMF) without cladding spliced between two single mode fibers (SMF). The MMI pressure sensor is based on the intensity changes that occur in the transmitted light when the effective refractive index of the MMF is changed. Basically, a thick layer of Polydimethylsiloxane (PDMS) is placed in direct contact with the MMF section, such that the contact area between the PDMS and the fiber will change proportionally with the applied pressure, which results in a variation of the transmitted light intensity. Using this configuration, a good correlation between the measured intensity variations and the applied pressure is obtained. The sensitivity of the sensor is 3 ?V/psi, for a range of 0-60 psi, and the maximum resolution of our system is 0.25 psi. Good repeatability is also observed with a standard deviation of 0.0019. The key feature of the proposed pressure sensor is its low fabrication cost, since the cost of the MMF is minimal.

Ruiz-Pérez, V. I.; Basurto-Pensado, M. A.; LiKamWa, P.; Sánchez-Mondragón, J. J.; May-Arrioja, D. A.

2011-01-01

392

Fiber-optically sensorized composite wing  

Science.gov (United States)

Electromagnetic interference (EMI) immune and light-weight, fiber-optic sensor based Structural Health Monitoring (SHM) will find increasing application in aerospace structures ranging from aircraft wings to jet engine vanes. Intelligent Fiber Optic Systems Corporation (IFOS) has been developing multi-functional fiber Bragg grating (FBG) sensor systems including parallel processing FBG interrogators combined with advanced signal processing for SHM, structural state sensing and load monitoring applications. This paper reports work with Auburn University on embedding and testing FBG sensor arrays in a quarter scale model of a T38 composite wing. The wing was designed and manufactured using fabric reinforced polymer matrix composites. FBG sensors were embedded under the top layer of the composite. Their positions were chosen based on strain maps determined by finite element analysis. Static and dynamic testing confirmed expected response from the FBGs. The demonstrated technology has the potential to be further developed into an autonomous onboard system to perform load monitoring, SHM and Non-Destructive Evaluation (NDE) of composite aerospace structures (wings and rotorcraft blades). This platform technology could also be applied to flight testing of morphing and aero-elastic control surfaces.

Costa, Joannes M.; Black, Richard J.; Moslehi, Behzad; Oblea, Levy; Patel, Rona; Sotoudeh, Vahid; Abouzeida, Essam; Quinones, Vladimir; Gowayed, Yasser; Soobramaney, Paul; Flowers, George

2014-04-01

393

Utilization of fiber optics in radiation diagnostics  

International Nuclear Information System (INIS)

Fiber optics can provide a cost effective transmission medium for wide bandwidth radiation diagnostics. Passive systems have been investigated which allow conversion of radiation energy to optical energy with direct coupling to optical fibers. Organic scintillators have been developed which emit at wavelengths near 600 nm. The new scintillators yield a FWHM below 1.5 ns. The scintillator emission band is very broad, leading to the requirement of optical filtering to limit material dispersion in the fiber. Trade-offs involving fiber length, dynamic range, fiber radiation damage, scintillator radiation damage, bandwidth, and spectral filter width are discussed

394

Fabrication of a Porous Fiber Cladding Material Using Microsphere Templating for Improved Response Time with Fiber Optic Sensor Arrays  

OpenAIRE

A highly porous optical-fiber cladding was developed for evanescent-wave fiber sensors, which contains sensor molecules, maintains guiding conditions in the optical fiber, and is suitable for sensing in aqueous environments. To make the cladding material (a poly(ethylene) glycol diacrylate (PEGDA) polymer) highly porous, a microsphere templating strategy was employed. The resulting pore network increases transport of the target analyte to the sensor molecules located in the cladding, which im...

Henning, Paul E.; Rigo, M. Veronica; Geissinger, Peter

2012-01-01

395

An in-fiber integrated optofluidic device based on an optical fiber with an inner core.  

Science.gov (United States)

A new kind of optofluidic in-fiber integrated device based on a specially designed hollow optical fiber with an inner core is designed. The inlets and outlets are built by etching the surface of the optical fiber without damaging the inner core. A reaction region between the end of the fiber and a solid point obtained after melting is constructed. By injecting samples into the fiber, the liquids can form steady microflows and react in the region. Simultaneously, the emission from the chemiluminescence reaction can be detected from the remote end of the optical fiber through evanescent field coupling. The concentration of ascorbic acid (AA or vitamin C, Vc) is determined by the emission intensity of the reaction of Vc, H2O2, luminol, and K3Fe(CN)6 in the optical fiber. A linear sensing range of 0.1-3.0 mmol L(-1) for Vc is obtained. The emission intensity can be determined within 2 s at a total flow rate of 150 ?L min(-1). Significantly, this work presents information for the in-fiber integrated optofluidic devices without spatial optical coupling. PMID:24799034

Yang, Xinghua; Yuan, Tingting; Teng, Pingping; Kong, Depeng; Liu, Chunlan; Li, Entao; Zhao, Enming; Tong, Chengguo; Yuan, Libo

2014-06-21

396

Optical fiber temperature sensors: applications in heat treatments for foods  

Science.gov (United States)

Heat treatments are important methods to provide safe foods. Conventional heat treatments involve the application of steam and recently microwave treatments have been studied and applied as they are considered as fast, clean and efficient. Optical fiber sensing is an excellent tool to measure the temperature during microwave treatments. This paper shows the application of optical fiber temperature sensing during the heat treatment of different foods such as vegetables (jalapeño pepper and cilantro), cheese and ostrich meat. Reaching the target temperature, important bacteria were inactivated: Salmonella, Listeria and Escherichia coli. Thus, the use of optical fiber sensors has resulted be a useful way to develop protocols to inactivate microorganisms and to propose new methods for food processing.

Sosa-Morales, María Elena; Rojas-Laguna, Roberto; López-Malo, Aurelio

2010-10-01

397

Structural health monitoring with fiber optic sensors  

Science.gov (United States)

SHM is defined as the process of acquiring and analyzing data from on-board sensors to evaluate the health of a structure. Most common damages on aircrafts are local cracks and delaminations, that do not change strongly the overall strain field, but that will act as the failure initiation point. Fiber optic sensors act primarily as strain sensors, so unless damage happens very close to the sensor location, it may go undetected. Currently, three main approaches for detecting damage from strain measurements are being investigated: 1) High resolution fibre optic distributed sensing (OFDR Rayleigh scattering). 2) Strain mapping with a dense network of sensors. Statistical analysis tools, like PCA, have been successfully used. 3) Hybrid FBG/PZT systems. FBGs must detect the ultrasonic elastic waves.

Güemes, Alfredo; Fernandez-Lopez, Antonio

2014-05-01

398

Applications of capillary optical fibers  

Science.gov (United States)

The paper updates and summarizes contemporary applications of capillary optical fibers. Some of these applications are straight consequence of the classical capillary properties and capillary devices like: rheometry, electrophoresis, column chromatography (gas and liquid). Some new applications are tightly connected with co-propagation (or counter-propagation) of micro-mass together with optical wave - evanescent or of considerable intensity. In the first case, the optical wave is propagated in a narrow (more and more frequently single-mode) optical ring core adjacent to the capillary hole. The optical propagation is purely refractive. In the second case, the intensity maximum of optical wave is on the capillary long axis, i.e. in the center of the hole. The optical propagation is purely photonic, i.e. in a Bragg waveguide (one dimensional photonic band-gap). The capillary hole is filled with vacuum or with propagated matter (gas, liquid, single atoms, continuous particle arrangement). Optical capillaries, filamentary and embedded, are turning to a fundamental component of nano- and micro-MOEMS.

Romaniuk, Ryszard

2006-10-01

399

Photonic Properties of ti Doped Optical Fiber  

Science.gov (United States)

The photonic properties of Ti doped optical fiber were investigated for application of optical nonlinear devices and a fiber-type UV sensor based on its high third order optical nonlinearity and photoluminescence characteristics. The structure and defect states of Ti incorporated in silica glass network of the fiber core were examined by measurement of optical properties such as optical absorption, photoluminescence, Raman shift, and by transmission electron microscopy. The nonlinear refractive index, n2, of the fiber was measured to be 5.73 × 10-20 m2/W by continuous-wave self-phase modulation method, which was 2.5 times larger than that of the same optical fiber without Ti incorporation. The photoluminescence of the Ti doped optical fiber was found to appear over the range from 360 nm to 480 nm upon the Xenon-lamp illumination, and it was found to increase linearly with the increase of the lamp power.

Kim, Youngwoong; Ju, Seongmin; Jeong, Seongmook; Han, Won-Taek

400

Fiber optic probes for laser light scattering: Ground based evaluation for micgrogravity flight experimentation. Integrated coherent imaging fiber optic systems for laser light scattering and other applications  

Science.gov (United States)

The research work presented in this report has established a new class of backscatter fiber optics probes for remote dynamic light scattering capability over a range of scattering angles from 94 degrees to 175 degrees. The fiber optic probes provide remote access to scattering systems, and can be utilized in either a noninvasive or invasive configuration. The fiber optics create an interference free data channel to inaccessible and harsh environments. Results from several studies of concentrated suspension, microemulsions, and protein systems are presented. The second part of the report describes the development of a new technology of wavefront processing within the optical fiber, that is, integrated fiber optics. Results have been very encouraging and the technology promises to have significant impact on the development of fiber optic sensors in a variety of fields ranging from environmental monitoring to optical recording, from biomedical sensing to photolithography.

Dhadwal, Harbans Singh

1994-01-01

401

Miners-Iron test of optical fibers  

International Nuclear Information System (INIS)

An experiment is described in which a number of optical fibers will be exposed to nuclear radiation in the Miners-Iron event at the Nevada Test Site. Two polymer clad silicon fibers and a borosilicate clad fiber will experience a dose of several Mrads, while a second set will experience about 0.1 Mrad. Attenuation and luninescence experiments are planned. Optic fibers will also be used for cables

402

Optical Fiber Grating based Sensors  

DEFF Research Database (Denmark)

In this thesis differenct optical fiber gratings are used for sensor purposes. If a fiber with a core concentricity error (CCE) is used, a directional dependent bend sensor can be produced. The CCE direction can be determined by means of diffraction. This makes it possible to produce long-period gratings in a fiber with a CCE direction parallel or perpendicular to the writing direction. The maximal bending sensitivity is independent on the writing direction, but the detailed bending response is different in the two cases. A temperature and strain sensor, based on a long-period grating and two sampled gratings, was produced and investigated. It is based on the different temperature and strain response of these gratings. Both a transfer matrix method and an overlap calculation is performed to explain the sensor response. Another type of sensor is based on tuning and modulation of a laser wavelength. It is shown that it is possible to tune and modulate a DFB fiber laser with both strain from a piezoelectric transducer and by temperature through resistive heating of a methal film. Both a chemical deposited silver layer and an electron-beam evaporation technique has been investigated, to find the most reproducible method. Such a laser can be applied for gas monitoring and it can be stabilized by locking it to an absorption line. The locked laser has a stability of ~2 MHz, which makes it suitable as a wavelength standard in the 1.5 um telecommunication band.

Michelsen, Susanne

2003-01-01

403

Fiber Optics Physics and Technology  

CERN Document Server

Telephone, telefax, email and internet -- the key ingredient of the inner workings is the conduit: the line which is designed to carry massive amounts of data at breakneck speed. In their data-carrying capacity optical fiber lines beat other technologies (copper cable, microwave beacons, satellite links) hands down, at least in the long haul. This book tells you all you want to know about optical fibers: Their structure, their light-guiding mechanism, their material and manufacture, their use. Several effects tend to degrade the signal as it travels down the fiber: they are spelled out in detail. Nonlinear processes are given due consideration for a twofold reason: On the one hand they are fundamentally different from the more familiar processes in electrical cable. On the other hand, they form the basis of particularly interesting and innovative applications, provided they are understood well enough. A case in point is the use of so-called solitons, i.e. special pulses of light which have the wonderful prope...

Mitschke, Fedor

2010-01-01

404

Fiber-Optic Ammonia Sensors  

Science.gov (United States)

Reversible, colorimetric fiber-optic sensors are undergoing development for use in measuring concentrations of ammonia in air at levels relevant to human health [0 to 50 parts per million (ppm)]. A sensor of this type includes an optical fiber that has been modified by replacing a portion of its cladding with a polymer coat that contains a dye that reacts reversibly with ammonia and changes color when it does so. The change in color is measured as a change in the amount of light transmitted from one end of the fiber to the other. Responses are reversible and proportional to the concentration of ammonia over the range from 9 to 175 ppm and in some cases the range of reversibility extends up to 270 ppm. The characteristic time for the response of a sensor to rise from 10 to 90 percent of full scale is about 25 seconds. These sensors are fully operational in pure carbon dioxide and are not adversely affected by humidity. This work was done by Michael T. Carter

Carter, Michael T.

2003-01-01

405

Qualification of a truly distributed fiber optic technique for strain and temperature measurements in concrete structures  

OpenAIRE

Structural health monitoring is a key factor in life cycle management of infrastructures. Truly distributed fiber optic sensors are able to provide relevant information on large structures, such as nuclear power plants or nuclear waste disposal facilities. The sensing chain includes an optoelectronic unit and a sensing cable made of one or more optical fibers. A new instrument based on Optical Frequency Domain Reflectometry (OFDR), enables to perform temperature and strain measurements with a...

Taillade F.; Bertand J.; Delepine-Lesoille S.; Moreau G.; Salin J.; Henault J.M.; Quiertant M.; Benzarti K.

2010-01-01

406

A Fiber-Tip Label-Free Biological Sensing Platform: A Practical Approach toward In-Vivo Sensing  

Directory of Open Access Journals (Sweden)

Full Text Available The platform presented here was devised to address the unmet need for real time label-free in vivo sensing by bringing together a refractive index transduction mechanism based on Whispering Gallery Modes (WGM in dye doped microspheres and Microstructured Optical Fibers. In addition to providing remote excitation and collection of the WGM signal, the fiber provides significant practical advantages such as an easy manipulation of the microresonator and the use of this sensor in a dip sensing architecture, alleviating the need for a complex microfluidic interface. Here, we present the first demonstration of the use of this approach for biological sensing and evaluate its limitation in a sensing configuration deprived of liquid flow which is most likely to occur in an in vivo setting. We also demonstrate the ability of this sensing platform to be operated above its lasing threshold, enabling enhanced device performance.

Alexandre François

2015-01-01

407

A fiber-tip label-free biological sensing platform: a practical approach toward in-vivo sensing.  

Science.gov (United States)

The platform presented here was devised to address the unmet need for real time label-free in vivo sensing by bringing together a refractive index transduction mechanism based on Whispering Gallery Modes (WGM) in dye doped microspheres and Microstructured Optical Fibers. In addition to providing remote excitation and collection of the WGM signal, the fiber provides significant practical advantages such as an easy manipulation of the microresonator and the use of this sensor in a dip sensing architecture, alleviating the need for a complex microfluidic interface. Here, we present the first demonstration of the use of this approach for biological sensing and evaluate its limitation in a sensing configuration deprived of liquid flow which is most likely to occur in an in vivo setting. We also demonstrate the ability of this sensing platform to be operated above its lasing threshold, enabling enhanced device performance. PMID:25585104

François, Alexandre; Reynolds, Tess; Monro, Tanya M

2015-01-01

408

Dual-pump sweep-free stimulated Brillouin optical distributed sensing method and device  

OpenAIRE

The present invention concerns a Brillouin optical distributed sensing method, comprising steps of: (i) providing a first and a second optical pulsed pump wave (20, 23) and an optical probe wave comprising at least one probe spectral component (26), (ii) detecting a stimulated Brillouin scattering signal resulting from the interactions in a sensing optical fiber of the optical probe wave with the first and the second optical pulsed pump waves (20, 23), (iii) spectrally arranging the first and...

The?venaz, Luc; Gonzalez Herraez, Miguel; Le Floch, Se?bastien; Chin, Sanghoon; Sauser, Florian

2014-01-01

409

Optical Fiber Sensor Instrumentation for Slagging Coal Gasifiers  

Energy Technology Data Exchange (ETDEWEB)

Coal gasifier is one of the most promising solutions for clean fossil energy. Refractory thickness monitoring and online real-time temperature measurement is needed for improved reliability and advanced process control for current and future generation power plants. The objective of this program is to design and implement an optical fiber based sensing system that could potentially be used to monitor refractory wall thickness and temperature inside a coal gasifier. For the thickness monitoring, the system should be able to operate at temperatures up to 1000 C. For this temperature range, silica fiber can still work so it is chosen for the sensor design. The measurement is based on a photon counting optical time domain reflectometer. A narrow light pulse is launched into a silica fiber which could be embedded into the gasifier refractory wall, and is partially reflected by the far end of the fiber. The time of flight of the light pulse in the fiber then gives an indication of the position of the fiber end, which is a function of the wall thickness when the fiber is embedded. Results obtained show a measurement accuracy of {+-}2cm in environment of 1000 C with a saw cut fiber end. When the fiber end is corroded by sodium carbide at 900 C, the accuracy is {+-}3cm. For the temperature measurement, a single crystal sapphire fiber sensor is designed. The sapphire fiber guides the broadband light from a light emitting diode to a sapphire wafer functioning as a Fabry-Perot interferometer and the wafer optical thickness is a function of temperature. The returned optical signal is then demodulated by multimode fiber based whitelight interferometry. The system was tested up to 1500 C with a measurement accuracy of {+-}10 C for the entire measurement range.

Anbo Wang; Kristie Cooper

2008-07-19

410

Air backed mandrel type fiber optic hydrophone with low noise floor  

Science.gov (United States)

Low noise fiber optic hydrophone based on optical fiber coil wound on air-backed mandrel was developed. The sensor can be effectively used for underwater acoustic sensing. The design and characterization of the hydrophone is illustrated in this paper. A fiber Mach-Zehnder Interferometer (MZI) was developed and coupled with a Distributed Feedback (DFB) fiber laser source and an optical phase demodulation system, with an active modulation in one of the arms. The sensor head design was optimized to achieve noise spectral density <10 ?rad/?Hz, for yielding sufficient sensitivity to sense acoustic pressure close to Deep Sea Sate Zero (DSS0).

Rajesh, R.; V, Sreehari C.; N, Praveen Kumar; Awasthi, R. L.; K, Vivek; B, Vishnu M.; Santhanakrishnan, T.; Moosad, K. P. B.; Mathew, Basil

2014-10-01

411

Thermal Strain Analysis of Optic Fiber Sensors  

OpenAIRE

An optical fiber sensor surface bonded onto a host structure and subjected to a temperature change is analytically studied in this work. The analysis is developed in order to assess the thermal behavior of an optical fiber sensor designed for measuring the strain in the host structure. For a surface bonded optical fiber sensor, the measuring sensitivity is strongly dependent on the bonding characteristics which include the protective coating, adhesive layer and the bonding length. Thermal str...

Chih-Ying Huang; Shiuh-Chuan Her

2013-01-01

412

Fiber-optical accelerometers based on polymer optical fiber Bragg gratings  

DEFF Research Database (Denmark)

Fiber-optical accelerometers based on polymer optical fiber Bragg gratings (FBGs) are reported. We have written 3mm FBGs for 1550nm operation, characterized their temperature and strain response, and tested their performance in a prototype accelerometer.

Yuan, Scott Wu; Stefani, Alessio

2010-01-01

413

Grazing incidence angle based sensing approach integrated with fiber-optic Fourier transform infrared (FO-FTIR) spectroscopy for remote and label-free detection of medical device contaminations  

International Nuclear Information System (INIS)

Contamination of medical devices has become a critical and prevalent public health safety concern since medical devices are being increasingly used in clinical practices for diagnostics, therapeutics and medical implants. The development of effective sensing methods for real-time detection of pathogenic contamination is needed to prevent and reduce the spread of infections to patients and the healthcare community. In this study, a hollow-core fiber-optic Fourier transform infrared spectroscopy methodology employing a grazing incidence angle based sensing approach (FO-FTIR-GIA) was developed for detection of various biochemical contaminants on medical device surfaces. We demonstrated the sensitivity of FO-FTIR-GIA sensing approach for non-contact and label-free detection of contaminants such as lipopolysaccharide from various surface materials relevant to medical device. The proposed sensing system can detect at a minimum loading concentration of approximately 0.7 ?g/cm2. The FO-FTIR-GIA has the potential for the detection of unwanted pathogen in real time

414

Grazing incidence angle based sensing approach integrated with fiber-optic Fourier transform infrared (FO-FTIR) spectroscopy for remote and label-free detection of medical device contaminations.  

Science.gov (United States)

Contamination of medical devices has become a critical and prevalent public health safety concern since medical devices are being increasingly used in clinical practices for diagnostics, therapeutics and medical implants. The development of effective sensing methods for real-time detection of pathogenic contamination is needed to prevent and reduce the spread of infections to patients and the healthcare community. In this study, a hollow-core fiber-optic Fourier transform infrared spectroscopy methodology employing a grazing incidence angle based sensing approach (FO-FTIR-GIA) was developed for detection of various biochemical contaminants on medical device surfaces. We demonstrated the sensitivity of FO-FTIR-GIA sensing approach for non-contact and label-free detection of contaminants such as lipopolysaccharide from various surface materials relevant to medical device. The proposed sensing system can detect at a minimum loading concentration of approximately 0.7 ?g/cm(2). The FO-FTIR-GIA has the potential for the detection of unwanted pathogen in real time. PMID:25362372

Hassan, Moinuddin; Ilev, Ilko

2014-10-01

415

Grazing incidence angle based sensing approach integrated with fiber-optic Fourier transform infrared (FO-FTIR) spectroscopy for remote and label-free detection of medical device contaminations  

Science.gov (United States)

Contamination of medical devices has become a critical and prevalent public health safety concern since medical devices are being increasingly used in clinical practices for diagnostics, therapeutics and medical implants. The development of effective sensing methods for real-time detection of pathogenic contamination is needed to prevent and reduce the spread of infections to patients and the healthcare community. In this study, a hollow-core fiber-optic Fourier transform infrared spectroscopy methodology employing a grazing incidence angle based sensing approach (FO-FTIR-GIA) was developed for detection of various biochemical contaminants on medical device surfaces. We demonstrated the sensitivity of FO-FTIR-GIA sensing approach for non-contact and label-free detection of contaminants such as lipopolysaccharide from various surface materials relevant to medical device. The proposed sensing system can detect at a minimum loading concentration of approximately 0.7 ?g/cm2. The FO-FTIR-GIA has the potential for the detection of unwanted pathogen in real time.

Hassan, Moinuddin; Ilev, Ilko

2014-10-01

416

Large-scale multiplexed fiber optic arrays for geophysical applications  

Science.gov (United States)

Fiber optic sensors are becoming a well-established technology for a range of geophysical applications, and static pressure and temperature sensors in particular are now comparatively well developed. However, rather less attention has been paid to systems for measuring dynamic quantities such as acoustic and seismic signals. Furthermore, the very large multiplexing potential of fiber optic sensing systems has yet to be fully explored for geophysical applications. However, development of fiber optic sonar systems for military applications has proven the viability of large multiplexed arrays, and demonstrated advantages which include electrically passive arrays, long term reliability and the potential for operation in very deep ($GTR3000m) water. This paper describes the applications for large scale fiber optic sensing arrays in geophysical metrology. The main applications considered here are ocean bottom cables and streamers for marine seismic, and downwell seismic systems. Systems can require up to several thousand channels and the use of multi- component sensors, which include 3-axis geophones and hydrophones. The paper discusses the specific requirements for each application, and shows how these requirements can be met using a system approach based on time and wavelength multiplexing of interferometric sensors. Experimental and theoretical studies at DERA into the performance of highly multiplexed systems are also described, together with initial development work on fiber optic hydrophones and geophones.

Nash, Phillip J.; Cranch, Geoffrey A.; Hill, David J.

2000-12-01

417

Interferometric microstructured polymer optical fiber ultrasound sensor for optoacoustic endoscopic imaging in biomedical applications  

Science.gov (United States)

We report a characterization of the acoustic sensitivity of microstructured polymer optical fiber interferometric sensors at ultrasonic frequencies from 100kHz to 10MHz. The use of wide-band ultrasonic fiber optic sensors in biomedical ultrasonic and optoacoustic applications is an open alternative to conventional piezoelectric transducers. These kind of sensors, made of biocompatible polymers, are good candidates for the sensing element in an optoacoustic endoscope because of its high sensitivity, its shape and its non-brittle and non-electric nature. The acoustic sensitivity of the intrinsic fiber optic interferometric sensors depends strongly of the material which is composed of. In this work we compare experimentally the intrinsic ultrasonic sensitivities of a PMMA mPOF with other three optical fibers: a singlemode silica optical fiber, a single-mode polymer optical fiber and a multimode graded-index perfluorinated polymer optical fiber.

Gallego, Daniel; Sáez-Rodríguez, David; Webb, David; Bang, Ole; Lamela, Horacio

2014-05-01

418

Optical fiber pressure sensor based on fiber Bragg grating  

Science.gov (United States)

In oil field, it is important to measure the high pressure and temperature for down-hole oil exploration and well-logging, the available traditional electronic sensor is challenged due to the harsh, flammable environment. Recently, applications based on fiber Bragg grating (FBG) sensor in the oil industry have become a popular research because of its distinguishing advantages such as electrically passive operation, immunity to electromagnetic interference, high resolution, insensitivity to optical power fluctuation etc. This thesis is divided into two main sections. In the first section, the design of high pressure sensor based on FBG is described. Several sensing elements based on FBG for high pressure measurements have been proposed, for example bulk-modulus or free elastic modulus. But the structure of bulk-modulus and free elastic modulus is relatively complex and not easy to fabricate. In addition, the pressure sensitivity is not high and the repeatability of the structure has not been investigated. In this thesis, a novel host material of carbon fiber laminated composite (CFLC) for high pressure sensing is proposed. The mechanical characteristics including principal moduli in three directions and the shape repeatability are investigated. Because of it's Young's modulus in one direction and anisotropic characteristics, the pressure sensor made by CFLC has excellent sensitivity. This said structure can be used in very high pressure measurement due to carbon fiber composite's excellent shape repetition even under high pressure. The experimental results show high pressure sensitivity of 0.101nm/MPa and high pressure measurement up to 70MPa. A pressure sensor based on CFLC and FBG with temperature compensation has been designed. In the second section, the design of low pressure sensor based on FBG is demonstrated. Due to the trade off between measurement range and sensitivity, a sensor for lower pressure range needs more sensitivity. A novel material of carbon fiber ribbon-wound composite cylindrical shell is proposed. The mechanical characteristics are analyzed. Due to the smaller longitudinal Young's modulus of this novel material, the sensitivity is improved to 0.452nm/MPa and the measurement range can reach 8MPa. The experimental results indicated excellent repeatability of the material and a good linearity between Bragg wavelength shift and the applied pressure. The sensor has the potential to find many industrial low pressure applications.

Song, Dongcao

419

Optical Fiber Embedded in Epoxy Glass Unidirectional Fiber Composite System  

Directory of Open Access Journals (Sweden)

Full Text Available We aimed to embed silica optical fibers in composites (epoxy vinyl ester matrix reinforced with E-glass unidirectional fibers in mass fraction of 60% in order to further monitor the robustness of civil engineering structures (such as bridges. A simple system was implemented using two different silica optical fibers (F1—double coating of 172 µm diameter and F2—single coating of 101.8 µm diameter respectively. The optical fibers were dynamically tensile tested and Weibull plots were traced. Interfacial adhesion stress was determined using pull-out test and stress values were correlated to fracture mechanisms based on SEM observations. In the case of the optical fiber (OF (F1/resin system and OF (F1/composite system, poor adhesion was reported that may be correlated to interface fracture at silica core level. Relevant applicable results were determined for OF (F2/composite system.

Irina Severin

2013-12-01

420

Brillouin Corrosion Expansion Sensors for Steel Reinforced Concrete Structures Using a Fiber Optic Coil Winding Method  

OpenAIRE

In this paper, a novel kind of method to monitor corrosion expansion of steel rebars in steel reinforced concrete structures named fiber optic coil winding method is proposed, discussed and tested. It is based on the fiber optical Brillouin sensing technique. Firstly, a strain calibration experiment is designed and conducted to obtain the strain coefficient of single mode fiber optics. Results have shown that there is a good linear relationship between Brillouin frequency and applied strain. ...

Xingjun Lv; Jinping Ou; Jie Lu(IFIC, Universitat de València – CSIC, Apt. Correus 22085, E-46071 València, Spain); Guofu Qiao; Peng Gong; Xuefeng Zhao

2011-01-01