WorldWideScience
 
 
1

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

2

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

3

Fiber optic sensing system  

Science.gov (United States)

A fiber optic interferometer utilizes a low coherence light emitting diode (LED) laser as a light source which is filtered and driven at two RF frequencies, high and low, that are specific to the initial length of the resonator chamber. A displacement of a reflecting mirror changes the length traveled by the nonreferencing signal. The low frequency light undergoes destructive interference which reduces the average intensity of the wave while the high frequency light undergoes constructive interference which increases the average intensity of the wave. The ratio of these two intensity measurements is proportional to the displacement incurred.

Adamovsky, Grigory (inventor)

1991-01-01

4

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

5

Fiber Optic-Based Refractive Index Sensing at INESC Porto  

Science.gov (United States)

A review of refractive index measurement based on different types of optical fiber sensor configurations and techniques is presented. It addresses the main developments in the area, with particular focus on results obtained at INESC Porto, Portugal. The optical fiber sensing structures studied include those based on Bragg and long period gratings, on micro-interferometers, on plasmonic effects in fibers and on multimode interference in a large spectrum of standard and microstructured optical fibers. PMID:22969405

Jorge, Pedro A. S.; Silva, Susana O.; Gouveia, Carlos; Tafulo, Paula; Coelho, Luis; Caldas, Paulo; Viegas, Diana; Rego, Gaspar; Baptista, Jose M.; Santos, Jose L.; Frazao, Orlando

2012-01-01

6

Fiber Optic-Based Refractive Index Sensing at INESC Porto  

Directory of Open Access Journals (Sweden)

Full Text Available A review of refractive index measurement based on different types of optical fiber sensor configurations and techniques is presented. It addresses the main developments in the area, with particular focus on results obtained at INESC Porto, Portugal. The optical fiber sensing structures studied include those based on Bragg and long period gratings, on micro-interferometers, on plasmonic effects in fibers and on multimode interference in a large spectrum of standard and microstructured optical fibers.

Orlando Frazão

2012-06-01

7

Application of Optical Fiber Sensing Technology to Ground Deformation Measurement  

Energy Technology Data Exchange (ETDEWEB)

A new method of applying optic fiber sensor to high accurate ground deformation measurement, which is based on the idea about the optic fiber interference combined with fiber grating and the utilization of the characteristics of Bragg wavelength absolute measurement and high accurate relative measurement with fiber interference, is proposed. This sensing system has many advantages, such as anti-interference, corrosion resistance, moisture proof, no zero drift and no need of calibration.

Feng Qian; Ding Wei; Wang Hao; Deng Taog, E-mail: fengqian@eqhb.gov.cn [Institute of Seismology, China Earthquake Administration, 40 Hongshan Ce Road, Wuchang District, Wuhan (China)

2011-02-01

8

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

9

Photoinduced Electron Transfer Based Ion Sensing within an Optical Fiber  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 ...

Monro, Tanya M.; Heike Ebendorff-Heidepriem; Sumby, Christopher J.; Richardson, Andrew C.; Tze Cheung Foo; Englich, Florian V.

2011-01-01

10

Fiber Optic-Based Refractive Index Sensing at INESC Porto  

Digital Repository Infrastructure Vision for European Research (DRIVER)

A review of refractive index measurement based on different types of optical fiber sensor configurations and techniques is presented. It addresses the main developments in the area, with particular focus on results obtained at INESC Porto, Portugal. The optical fiber sensing structures studied include those based on Bragg and long period gratings, on micro-interferometers, on plasmonic effects in fibers and on multimode interference in a large spectrum of standard and microstructured optical ...

2012-01-01

11

Fiber optic sensing technology: emerging markets and trends  

Science.gov (United States)

Recent technical advances in fiber optic sensor technology have brought fiber sensors into the mainstream. Using a wide variety of sensing elements, and interrogation techniques, these devices are finding applications in fields from power line management to homeland security. A variety of fiber sensor technologies, applications, and markets are discussed.

Huff, David B.; Lebby, Michael S.

2007-07-01

12

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

13

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

14

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

15

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

16

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

17

Extrinsic fiber optic displacement sensors and displacement sensing systems  

Science.gov (United States)

An extrinsic Fizeau fiber optic sensor comprises a single-mode fiber, used as an input/output fiber, and a multimode fiber, used purely as a reflector, to form an air gap within a silica tube that acts as a Fizeau cavity. The Fresnel reflection from the glass/air interface at the front of the air gap (reference reflection) and the reflection from the air/glass interface at the far end of the air gap (sensing reflection) interfere in the input/output fiber. The two fibers are allowed to move in the silica tube, and changes in the air gap length cause changes in the phase difference between the reference reflection and the sensing reflection. This phase difference is observed as changes in intensity of the light monitored at the output arm of a fused biconical tapered coupler. The extrinsic Fizeau fiber optic sensor behaves identically whether it is surface mounted or embedded, which is unique to the extrinsic sensor in contrast to intrinsic Fabry-Perot sensors. The sensor may be modified to provide a quadrature phase shift extrinsic Fizeau fiber optic sensor for the detection of both the amplitude and the relative polarity of dynamically varying strain. The quadrature light signals may be generated by either mechanical or optical means. A plurality of the extrinsic sensors may connected in cascade and multiplexed to allow monitoring by a single analyzer.

Murphy, Kent A. (Roanoke, VA); Gunther, Michael F. (Blacksburg, VA); Vengsarkar, Ashish M. (Scotch Plains, NJ); Claus, Richard O. (Christiansburg, VA)

1994-01-01

18

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

19

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

20

Progress in distributed fiber optic temperature sensing  

Science.gov (United States)

The paper reviews the adoption of distributed temperature sensing (DTS) technology based on Raman backscatter. With one company alone having installed more than 400 units, the DTS is becoming accepted practice in several applications, notably in energy cable monitoring, specialised fire detection and oil production monitoring. The paper will provide case studies in these applications. In each case the benefit (whether economic or safety) will be addressed, together with key application engineering issues. The latter range from the selection and installation of the fibre sensor, the specific performance requirements of the opto-electronic equipment and the issues of data management. The paper will also address advanced applications of distributed sensing, notably the problem of monitoring very long ranges, which apply in subsea DC energy cables or in subsea oil wells linked to platforms through very long (e.g. 30km flowlines). These applications are creating the need for a new generation of DTS systems able to achieve measurements at up to 40km with very high temperature resolution, without sacrificing spatial resolution. This challenge is likely to drive the development of new concepts in the field of distributed sensing.

Hartog, Arthur H.

2002-02-01

 
 
 
 
21

Basic study on radiation distribution sensing with normal optical fiber  

International Nuclear Information System (INIS)

Recently, some methods of radiation distribution sensing with optical fibers have been proposed. These methods employ scintillating fibers or scintillators with wavelength-shifting fibers. The positions of radiation interactions are detected by applying a time-of-flight (TOF) technique to the scintillation photon propagation. In the former method, the attenuation length for the scintillation photons in the scintillating fiber is relatively short, so that the operating length of the sensor is limited to several meters. In the latter method, a radiation distribution cannot continuously be obtained but discretely. To improve these shortcomings, a normal optical fiber made of polymethyl methacrylate (PMMA) is used in this study. Although the scintillation efficiency of PMMA is very low, several photons are emitted through interaction with a radiation. The fiber is transparent for the emitted photons to have a relatively long operating length. A radiation distribution can continuously be obtained. This paper describes a principle of the position sensing method based on the time of flight technique and preliminary results obtained for 90Sr-90Y beta rays, 137Cs gamma rays, and 14 MeV neutrons. The spatial resolutions for the above three kinds of radiations are 0.30 m, 0.37 m, 0.13 m, and the detection efficiencies are 1.1 x 10-3, 1.6 x 10-7, 5.4 x 10-6, respectively, with 10 m operation length. The results of a spectroscopic study on the optical property of the fiber are also described. (author)

22

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

23

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

24

Practical applications of temperature distribution sensing by Raman backscattering in optical fibers  

Science.gov (United States)

Distributed temperature sensing by Raman backscattering in optical fibers is unique technology which makes full use of the features of the optical fibers. This paper describes practical applications of the sensor: pipe line maintenance, electric cable maintenance, and road maintenance.

Yamauchi, Ryozo R.; Shiota, Alan T.

1993-03-01

25

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

26

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

27

Fiber-Optic Photoelastic Device Senses Pressure Of Hot Gas  

Science.gov (United States)

Fiber-optic/photoelastic device measures gas pressures up to 600 psi at operating temperatures as high as 1,100 degrees C. Pressure on fused-silica sensing element gives rise to birefringence via photoelastic effect. Polarization of light changed by birefringence; change in polarization measured and used to infer pressure causing it. Device prototype of gas-pressure sensor for aircraft engine. Mounted in engine at or near desired measurement point, where it responds to both time-varying and steady components of pressure.

Redner, Alex S.; Wesson, L. N.

1995-01-01

28

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

29

Recent network sensing based on a combination of single mode fiber optics and semiconductor lasers  

Science.gov (United States)

This paper describes the overview of the past decade's progress of network sensing supported by the use of single mode fiber optics in which glass fiber material itself exhibits sensing function, comparing with conventional FBG/BOTDR techniques, and newly developed hetero-core techniques. The hetero-core fiber optic sensor has been highlighted in terms of the fabrication process, the sensing mechanism and characteristics, and a road map toward commercialization to the variety of industrial applications.

Watanabe, Kazuhiro

2007-05-01

30

Fiber optic device for sensing the presence of a gas  

Science.gov (United States)

A fiber-optic device for sensing the presence of a gas in an environment is provided. The device comprises a light source for directing a light beam to a layer system having a first surface and a second surface opposite the first surface. The first surface is exposable to the light beam and the second surface is exposable to the environment. A first light portion encounters and reflects from the first surface at an angle of incidence free from optical wave guide resonance phenomenon and the second light portion encounters and reflects from the first surface at an angle of incidence enabling an optical wave guide resonance phenomenon. The layer system is selected to reversibly react with the gas to be detected. The reaction between the gas and the material changes the material`s optical properties and the wavelength at which the optical wave guide resonance occurs. Furthermore, a mechanism for measuring the intensity of the reflected first light portion relative to the reflected second light portion is provided with the ratio of the first and second light portions indicating the concentration of the gas presence in the environment. 5 figs.

Benson, D.K.; Bechinger, C.S.; Tracy, C.E.

1998-01-13

31

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

32

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

33

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

34

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

35

Fiber optic microphone having a pressure sensing reflective membrane and a voltage source for calibration purpose  

Science.gov (United States)

A fiber optic microphone is provided for measuring fluctuating pressures. An optical fiber probe having at least one transmitting fiber for transmitting light to a pressure-sensing membrane and at least one receiving fiber for receiving light reflected from a stretched membrane is provided. The pressure-sensing membrane may be stretched for high frequency response. Further, a reflecting surface of the pressure-sensing membrane may have dimensions which substantially correspond to dimensions of a cross section of the optical fiber probe. Further, the fiber optic microphone can be made of materials for use in high temperature environments, for example greater than 1000 F. A fiber optic probe is also provided with a back plate for damping membrane motion. The back plate further provides a means for on-line calibration of the microphone.

Zuckerwar, Allan J. (inventor); Cuomo, Frank W. (inventor); Robbins, William E. (inventor)

1993-01-01

36

Novel optical fibers for Brillouin-based distributed sensing  

Science.gov (United States)

Optical fiber sensors utilizing Brillouin scattering rely on the principle that the Brillouin frequency shift is a function of the local temperature or strain. Conventional optical fibers, such as standard telecommunications single-mode fibers, have been successfully used in these applications, and most typically in the time domain, such as with BOTDR. Such conventional fibers however are susceptible simultaneously to both temperature and strain, requiring either at least two fibers or specialized cabling to distinguish the effects of a local stress from those of a local change in temperature. Recently, methods utilizing fibers possessing at least two Brillouin frequency shifts, each with different temperature or strain coefficients have been proposed. However, realizing such fibers is challenging, requiring fibers with regions of very different compositions, all of which must have substantial overlap with the optical field, posing significant manufacturing challenges. We present several new specialty optical fibers based on novel and unconventional fabrication techniques with significant potential for use in distributed fiber sensor systems. First, we describe a class of fibers fabricated from materials whose Brillouin frequency shifts are immune to either temperature or strain, with a demonstration of the former using fiber derived from sapphire crystal, and modeling and measurements predicting the latter. The `Brillouin-athermal' fiber enables the measurement of a local strain, independent of the local temperature. Second, we describe and demonstrate a novel group of longitudinally graded (chirped) fibers enabling easily-implemented frequency-domain systems; affording the potential to simplify and reduce the cost of Brillouin-based distributed sensors.

Dragic, Peter D.; Ballato, John; Morris, Stephanie; Evert, Alex; Rice, Robert R.; Hawkins, Thomas

2013-05-01

37

Frequency-shifted interferometry--a versatile fiber-optic sensing technique.  

Science.gov (United States)

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. PMID:24955943

Ye, Fei; Zhang, Yiwei; Qi, Bing; Qian, Li

2014-01-01

38

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

39

Brief history of fiber optic sensing in the oil field industry  

Science.gov (United States)

The use of fiber optic sensing in the oil and gas industry has greatly expanded over the past two decades. Since the first optical fiber-based pressure sensor was installed in a well in 1993, the industry has sought to use fiber sensing technology to monitor in-well parameters. Through the years, optical fiber sensing has been used in an increasing number of applications as technical advances have opened the door for new measurements. Today, fiber optic sensors are used routinely to measure temperature throughout the wellbore. Optical sensors also provide pressure measurements at key locations within the well. These measurements are used to verify the integrity of the well, provide feedback during well completion operations, including the actuation of downhole valves, and to monitor the production or injection process. Other sensors, such as seismic monitors and flowmeters, use fiber sensing technology to make in-well measurements. Various optical sensing techniques are used to make these measurements, including Bragg grating, Raman scattering, and coherent Rayleigh scattering. These measurements are made in harsh environments, which require rugged designs for optical cable systems and instrumentation systems. Some of these applications have operating temperatures of 572°F (300°C), and other applications can have pressures in excess of 20,000 psi (1,379 bar). This paper provides a historical perspective on the use of fiber optic sensing in the oil and gas industry from industry firsts to current applications.

Baldwin, Christopher S.

2014-06-01

40

Spatially continuous distributed fiber optic sensing using optical carrier based microwave interferometry.  

Science.gov (United States)

This paper reports a spatially continuous distributed fiber optic sensing technique using optical carrier based microwave interferometry (OCMI), in which many optical interferometers with the same or different optical path differences are interrogated in the microwave domain and their locations can be unambiguously determined. The concept is demonstrated using cascaded weak optical reflectors along a single optical fiber, where any two arbitrary reflectors are paired to define a low-finesse Fabry-Perot interferometer. While spatially continuous (i.e., no dark zone), fully distributed strain measurement was used as an example to demonstrate the capability, the proposed concept may also be implemented on other types of waveguide or free-space interferometers and used for distributed measurement of various physical, chemical and biological quantities. PMID:25089493

Huang, Jie; Lan, Xinwei; Luo, Ming; Xiao, Hai

2014-07-28

 
 
 
 
41

Structural health monitoring of civil infrastructure using optical fiber sensing technology: a comprehensive review.  

Science.gov (United States)

In the last two decades, a significant number of innovative sensing systems based on optical fiber sensors have been exploited in the engineering community due to their inherent distinctive advantages such as small size, light weight, immunity to electromagnetic interference (EMI) and corrosion, and embedding capability. A lot of optical fiber sensor-based monitoring systems have been developed for continuous measurement and real-time assessment of diversified engineering structures such as bridges, buildings, tunnels, pipelines, wind turbines, railway infrastructure, and geotechnical structures. The purpose of this review article is devoted to presenting a summary of the basic principles of various optical fiber sensors, innovation in sensing and computational methodologies, development of novel optical fiber sensors, and the practical application status of the optical fiber sensing technology in structural health monitoring (SHM) of civil infrastructure. PMID:25133250

Ye, X W; Su, Y H; Han, J P

2014-01-01

42

Structural Health Monitoring of Civil Infrastructure Using Optical Fiber Sensing Technology: A Comprehensive Review  

Science.gov (United States)

In the last two decades, a significant number of innovative sensing systems based on optical fiber sensors have been exploited in the engineering community due to their inherent distinctive advantages such as small size, light weight, immunity to electromagnetic interference (EMI) and corrosion, and embedding capability. A lot of optical fiber sensor-based monitoring systems have been developed for continuous measurement and real-time assessment of diversified engineering structures such as bridges, buildings, tunnels, pipelines, wind turbines, railway infrastructure, and geotechnical structures. The purpose of this review article is devoted to presenting a summary of the basic principles of various optical fiber sensors, innovation in sensing and computational methodologies, development of novel optical fiber sensors, and the practical application status of the optical fiber sensing technology in structural health monitoring (SHM) of civil infrastructure. PMID:25133250

Ye, X. W.; Su, Y. H.; Han, J. P.

2014-01-01

43

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)

44

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

Directory of Open Access Journals (Sweden)

Full Text Available 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 includes a geophone or a microphone. Following confirmation of the reliability of the proposed sensing system, the fiber-optic sensing systems are deployed along the Ai-Yu-Zi and Chu-Shui Creeks in Nautou County of central Taiwan for monitoring debris flows. Sensitivity test of the deployed fiber-optic sensing system along the creek banks is also performed. Analysis results of the seismic data recorded by the systems reveal in detail the frequency characteristics of the artificially generated ground vibrations. Results of this study demonstrate that the proposed fiber-optic sensing system is highly promising for use in monitoring natural disasters that generate ground vibrations.

Tsung-Mo Tien

2012-05-01

45

Calibration and deployment of a fiber-optic sensing system for monitoring debris flows.  

Science.gov (United States)

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 includes a geophone or a microphone. Following confirmation of the reliability of the proposed sensing system, the fiber-optic sensing systems are deployed along the Ai-Yu-Zi and Chu-Shui Creeks in Nautou County of central Taiwan for monitoring debris flows. Sensitivity test of the deployed fiber-optic sensing system along the creek banks is also performed. Analysis results of the seismic data recorded by the systems reveal in detail the frequency characteristics of the artificially generated ground vibrations. Results of this study demonstrate that the proposed fiber-optic sensing system is highly promising for use in monitoring natural disasters that generate ground vibrations. PMID:22778616

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

2012-01-01

46

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

Science.gov (United States)

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. PMID:24379051

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

2014-01-01

47

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

48

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

49

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

Energy Technology Data Exchange (ETDEWEB)

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.

Jobmann, M.; Biurrun, E.

2003-02-24

50

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

51

Experimental study of liquid refractive index sensing based on a U-shaped optical fiber  

Science.gov (United States)

A U-shaped optical fiber sensing system designed to measure the refractive index of liquid had been proposed. The sensing mechanism of U-shaped optical fiber was discussed. A general single-mode fiber was bent into U-shaped and partially cladding of U-shaped fiber was corroded by HF acid buffer solution. Powers of different diameters of U-shaped fibers had been measured by many experiments. The results showed that the diameter of U-shaped fiber cladding 40 ?m and the diameter of U-shaped was 1 cm were suitable to measure liquid refractive index. Then, this U-shaped optical fiber was immersed in liquid, such as pure water, ethanol, acetone and isopropanol, respectively. The evanescent field of the U-shaped fiber should be modulated by the liquid. The optical signal in the U-shaped fiber was measured with the optical spectrum analyzers(OSA). Finally, the experimental results were analyzed, and the spectra in the air was selected as a reference. The relative intensity was obtained for the different liquid. These results showed that the relative intensity of the liquid had a good linear relationship. This sensing device could accurately demarcate refractive index of liquid. It is simple, low cost, and it can also be applied in measuring the level of liquid.

Zhang, Zhi; Yan, Haitao; Li, Liben; Wang, Ming

2013-12-01

52

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

53

Optical fiber magnetic field sensors with TbDyFe magnetostrictive thin films as sensing materials.  

Science.gov (United States)

Different from usually-used bulk magnetostrictive materials, magnetostrictive TbDyFe thin films were firstly proposed as sensing materials for fiber-optic magnetic field sensing characterization. By magnetron sputtering process, TbDyFe thin films were deposited on etched side circle of a fiber Bragg Grating (FBG) as sensing element. There exists more than 45pm change of FBG wavelength when magnet field increase up to 50 mT. The response to magnetic field is reversible, and could be applicable for magnetic and current sensing. PMID:19997310

Yang, Minghong; Dai, Jixiang; Zhou, Ciming; Jiang, Desheng

2009-11-01

54

Development of fiber-optic current sensing technique and its applications in electric power systems  

Science.gov (United States)

This paper describes the development and applications of a fiber-optic electric current sensing technique with the stable properties and compact, simple, and flexible structure of the sensing device. The special characteristics of the sensors were achieved by use of the special low birefringence fiber as the Faraday-effect sensing element and were also achieved with creation of sensing schemes which matched with the features of the fiber. Making use of the excellent features of the sensing technique, various current monitoring devices and systems were developed and applied practically for the control and maintenance in the electric power facility. In this paper, the design and performance of the sensing devices are introduced first. After that, examples of the application systems practically applied are also introduced, including fault section/point location systems for power transmission cable lines.

Kurosawa, Kiyoshi

2014-03-01

55

Fiber-optic chemical sensing with Langmuir-Blodgett overlay waveguides  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Fiber-optic chemical sensing has been demonstrated with a side-polished single- mode optical fiber, evanescently coupled to chemically sensitive Langmuir- Blodgett (LB) overlay waveguides. The sensors exhibit a channel-dropping response centered on a wavelength that is dependent on the thickness and the refractive index of the overlay waveguide. It has been shown that pH-sensitive organic dyes proved to be suitable materials fur the formation of an overlay waveguide whereas ...

Flannery, D.; James, Stephen W.; Tatam, Ralph P.; Ashwell, Geoffrey J.

1999-01-01

56

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

57

Electrically Insulated Sensing of Respiratory Rate and Heartbeat Using Optical Fibers  

Directory of Open Access Journals (Sweden)

Full Text Available Respiratory and heart rates are among the most important physiological parameters used to monitor patients’ health. It is important to design devices that can measure these parameters without risking or altering the subject’s health. In this context, a novel sensing method to monitor simultaneously the heartbeat and respiratory rate signals of patients within an electrically safety environment was developed and tested. An optical fiber-based sensor was used in order to detect two optical phenomena. Photo-plethysmography and the relation between bending radius and attenuation of optical fiber were coupled through a single beam light traveling along this fiber.

Ernesto Suaste-Gómez

2014-11-01

58

Electrically insulated sensing of respiratory rate and heartbeat using optical fibers.  

Science.gov (United States)

Respiratory and heart rates are among the most important physiological parameters used to monitor patients' health. It is important to design devices that can measure these parameters without risking or altering the subject's health. In this context, a novel sensing method to monitor simultaneously the heartbeat and respiratory rate signals of patients within an electrically safety environment was developed and tested. An optical fiber-based sensor was used in order to detect two optical phenomena. Photo-plethysmography and the relation between bending radius and attenuation of optical fiber were coupled through a single beam light traveling along this fiber. PMID:25405510

Suaste-Gómez, Ernesto; Hernández-Rivera, Daniel; Sánchez-Sánchez, Anabel S; Villarreal-Calva, Elsy

2014-01-01

59

Application research on hydraulic coke cutting monitoring system based on optical fiber sensing technology  

Science.gov (United States)

With the development of the optical fiber sensing technology, the acoustic emission sensor has become one of the focal research topics. On the basis of studying the traditional hydraulic coke cutting monitoring system, the optical fiber acoustic emission sensor has been applied in the hydraulic coke cutting monitoring system for the first time, researching the monitoring signal of the optical fiber acoustic emission sensor in the system. The actual test results show that using the acoustic emission sensor in the hydraulic coke cutting monitoring system can get the real-time and accurate hydraulic coke cutting state and the effective realization of hydraulic coke cutting automatic monitoring in the Wuhan Branch of Sinopec.

Zhong, Dong; Tong, Xinglin

2014-06-01

60

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

 
 
 
 
61

Sensing structure based on surface plasmonic resonance in single mode optical fibers chemically etched  

Science.gov (United States)

Many optical systems based on Surface Plasmon Resonance (SPR) have been developed for work as refractometers, chemical sensors or even for measure the thickness of metal and dielectric thin films. These kinds of systems are usually large, expensive and cannot be used for remote sensing. Optical fiber sensors based on SPR has been widely studied for the last 20 years with several configurations mostly using multimode optical fibers with large cores and plastic claddings. Sensors based on SPR present very high sensitivity to refractive index variations when compared to the traditional refractive index sensors. Here we propose a SPR sensor based in a single mode fiber. The fiber end is chemically etched by emersion in a 48% hydrofluoric acid solution, resulting a single mode fiber with the cladding removed in a small section. A resonance dip around 1580 nm was attained in good agreement with the simulation scenario that takes into account the real characteristics of the fiber.

Coelho, L.; Almeida, J. M.; Santos, J. L.; Ferreira, R. A. S.; André, P. S.; Viegas, D.

2013-05-01

62

Multilayer silver nanoparticles-modified optical fiber tip for high performance SERS remote sensing.  

Science.gov (United States)

This work presents the construction and optimization of nanoparticles-modified optical fiber tip (NPs-MOFT) devices for remote sensing by surface-enhanced Raman scattering (SERS). Silver nanoparticles (Ag-NPs) were self-assembled on optical fiber tips through a "layer-by-layer" procedure. It is shown that the SERS performance is at optimum when 5 "layers" of 50 nm Ag-NPs were deposited on the optical fiber tip. Using the optimized Ag-NPs-MOFT device, it was possible to detect 200 nM of the R6G dye in remote sensing mode (backscattering through the fiber). It was also possible to detect dye molecules with different structures and charges at the micro-molar concentration level, including anions, cations and neutral species. It can be envisioned that the Ag-NPs-MOFT device reported in this work can be further developed for SERS-based remote biosensing. PMID:20353887

Andrade, Gustavo F S; Fan, MeiKun; Brolo, Alexandre G

2010-06-15

63

Optical fiber based sensing system design for the health monitoring of multi-layered pavement structure  

Science.gov (United States)

This paper introduces an optical fiber based sensing system design for multi-layered pavement structural health monitoring. The co-line and integration design of FBG (Fiber Bragg Gating) sensors and BOTDR (Brillouin Optical Time Domain Reflectometry) sensors will ensure the large scale damage monitoring and local high accurate strain measurement. The function of pavement structure multi-scale shape measurement will provide real time subgrade settlement and rutting information. The sensor packaging methodology and strain transfer problem of the system will also be discussed in this paper. Primary lab tests prove the potential and feasibility of the practical application of the sensing system.

Liu, Wanqiu; Wang, Huaping; Zhou, Zhi; Li, Shiyu; Ni, Yuanbao; Wang, Geng

2011-11-01

64

Analysis of the Interference Signal of the Distributed Optical Fiber Sensing Based on DSP  

Directory of Open Access Journals (Sweden)

Full Text Available In this paper, the author analyzes characteristics and extracting method of interference signal of the distributed optical fiber sensing. In the distributed optical fiber sensing, realizing alarm and positioning function only through the cross-correlation operation will increase the load of the system, can make misinformation rate of the system be improved greatly. Therefore, before the localization algorithm, adding a interference signal feature recognition is very necessary, can reduce unnecessary operation loss and reduce the load of the system, also reducing the number of the false positives.

Tingting Du

2013-06-01

65

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

66

Assessment of fiber optic sensors and other advanced sensing technologies for nuclear power plants  

Energy Technology Data Exchange (ETDEWEB)

As a result of problems such as calibration drift in nuclear plant pressure sensors and the recent oil loss syndrome in some models of Rosemount pressure transmitters, the nuclear industry has become interested in fiber optic pressure sensors. Fiber optic sensing technologies have been considered for the development of advanced instrumentation and control (I&C) systems for the next generation of reactors and in older plants which are retrofitted with new I&C systems. This paper presents the results of a six-month Phase I study to establish the state-of-the-art in fiber optic pressure sensing. 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. This initial Phase I study has recently been granted a two-year extension by the U.S. Nuclear Regulatory Commission (NRC). The next phase will evaluate fiber optic pressure sensors in specific nuclear plant applications in addition to other advanced methods for monitoring critical nuclear plant equipment.

Hashemian, H.M. [Analysis and Measurement Services Corporation, Knoxville, TN (United States)

1996-03-01

67

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

68

Advanced end-to-end fiber optic sensing systems for demanding environments  

Science.gov (United States)

Optical fibers are small-in-diameter, light-in-weight, electromagnetic-interference immune, electrically passive, chemically inert, flexible, embeddable into different materials, and distributed-sensing enabling, and can be temperature and radiation tolerant. With appropriate processing and/or packaging, they can be very robust and well suited to demanding environments. In this paper, we review a range of complete end-to-end fiber optic sensor systems that IFOS has developed comprising not only (1) packaged sensors and mechanisms for integration with demanding environments, but (2) ruggedized sensor interrogators, and (3) intelligent decision aid algorithms software systems. We examine the following examples: " Fiber Bragg Grating (FBG) optical sensors systems supporting arrays of environmentally conditioned multiplexed FBG point sensors on single or multiple optical fibers: In conjunction with advanced signal processing, decision aid algorithms and reasoners, FBG sensor based structural health monitoring (SHM) systems are expected to play an increasing role in extending the life and reducing costs of new generations of aerospace systems. Further, FBG based structural state sensing systems have the potential to considerably enhance the performance of dynamic structures interacting with their environment (including jet aircraft, unmanned aerial vehicles (UAVs), and medical or extravehicular space robots). " Raman based distributed temperature sensing systems: The complete length of optical fiber acts as a very long distributed sensor which may be placed down an oil well or wrapped around a cryogenic tank.

Black, Richard J.; Moslehi, Behzad

2010-09-01

69

High-resolution absolute frequency referenced fiber optic sensor for quasi-static strain sensing  

Energy Technology Data Exchange (ETDEWEB)

We present a quasi-static fiber optic strain sensing system capable of resolving signals below nanostrain from 20 mHz. A telecom-grade distributed feedback CW diode laser is locked to a fiber Fabry-Perot sensor, transferring the detected signals onto the laser. An H{sup 13}C{sup 14}N absorption line is then used as a frequency reference to extract accurate low-frequency strain signals from the locked system.

Lam, Timothy T.-Y.; Chow, Jong H.; Shaddock, Daniel A.; Littler, Ian C. M.; Gagliardi, Gianluca; Gray, Malcolm B.; McClelland, David E.

2010-07-20

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

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

72

High temperature sensing with fiber Bragg gratings in sapphire-derived all-glass optical fibers.  

Science.gov (United States)

A structured sapphire-derived all-glass optical fiber with an aluminum content in the core of up to 50 mol% was used for fiber Bragg grating inscription. The fiber provided a parabolic refractive index profile. Fiber Bragg gratings were inscribed by means of femtosecond-laser pulses with a wavelength of 400 nm in combination with a two-beam phase mask interferometer. Heating experiments demonstrated the stability of the gratings for temperatures up to 950°C for more than 24 h without degradation in reflectivity. PMID:25401829

Elsmann, Tino; Lorenz, Adrian; Yazd, Nazila Safari; Habisreuther, Tobias; Dellith, Jan; Schwuchow, Anka; Bierlich, Jörg; Schuster, Kay; Rothhardt, Manfred; Kido, Ladislav; Bartelt, Hartmut

2014-11-01

73

Application of a distributed optical fiber sensing technique in monitoring the stress of precast piles  

Science.gov (United States)

Due to its ability in providing long distance, distributed sensing, the optical fiber sensing technique based on a Brillouin optical time domain reflectometer (BOTDR) has a unique advantage in monitoring the stability and safety of linear structures. This paper describes the application of a BOTDR-based technique to measure the stress within precast piles. The principle behind the BOTDR and the embedding technique for the sensing optical fiber in precast piles is first introduced, and then the analysis method and deformation and stress calculation based on distributed strain data are given. Finally, a methodology for using a BOTDR-based monitoring workflow for in situ monitoring of precast piles, combined with a practical example, is introduced. The methodology requires implantation of optical fibers prior to pile placement. Field experimental results show that the optical fiber implantation method with slotting, embedding, pasting and jointing is feasible, and have accurately measured the axial force, side friction, end-bearing resistance and bearing feature of the precast pile according to the strain measuring data.

Lu, Y.; Shi, B.; Wei, G. Q.; Chen, S. E.; Zhang, D.

2012-11-01

74

Application of a distributed optical fiber sensing technique in monitoring the stress of precast piles  

International Nuclear Information System (INIS)

Due to its ability in providing long distance, distributed sensing, the optical fiber sensing technique based on a Brillouin optical time domain reflectometer (BOTDR) has a unique advantage in monitoring the stability and safety of linear structures. This paper describes the application of a BOTDR-based technique to measure the stress within precast piles. The principle behind the BOTDR and the embedding technique for the sensing optical fiber in precast piles is first introduced, and then the analysis method and deformation and stress calculation based on distributed strain data are given. Finally, a methodology for using a BOTDR-based monitoring workflow for in situ monitoring of precast piles, combined with a practical example, is introduced. The methodology requires implantation of optical fibers prior to pile placement. Field experimental results show that the optical fiber implantation method with slotting, embedding, pasting and jointing is feasible, and have accurately measured the axial force, side friction, end-bearing resistance and bearing feature of the precast pile according to the strain measuring data. (paper)

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

Distributed fiber optical HC leakage and pH sensing techniques for implementation into smart structures  

Science.gov (United States)

Interaction of target molecules with the evanescent wave of light guided in optical fibers is among the most promising sensing schemes for building up smart chemical sensor technologies. If the technique of optical time domain reflectometry (OTDR) is combined with silicone-clad quartz glass fibers distributed chemical sensing is possible. Hydrocarbon (HC) detection and location is done by automated identification of the position of the corresponding step drop (light loss) in the backscatter signal induced by local refractive index increase in the silicone cladding due to a penetrating HC compound. A commercially available mini-OTDR was adapted to sensing fibers of up to nearly 2-kilometer length and location of typical HC fuels could be demonstrated. The instrument is applicable for fuel leakage monitoring in large technical installations such as tanks or pipelines with spatial resolution down to 1 m. A similar technique using measurements in the Vis spectral range is being developed for health monitoring of large structures, e.g., for early detection of corrosion caused by water ingress and pH changes in reinforced concrete. Here, a pH indicator dye and a phase transfer reagent are immobilized in the originally hydrophobic fiber cladding, leading to a pH induced absorption increase and a step drop signal in the backscatter curve. The configuration of the distributed sensing cables, the instrumental setups, and examples for HC and pH sensing are presented.

Buerck, Jochen M.; Vogel, Bernhard H.; Roth, Siegmar; Ebrahimi, Sasan; Kraemer, Karl

2004-07-01

77

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

78

A new optical fiber sensor for multipoint radiation measurement with sensing regions in its cladding  

International Nuclear Information System (INIS)

Current scintillating optical fibers for radiation measurement have drawbacks as high intrinsic and radiation-induced loss. In order to overcome these problems, a new optical fiber sensor for multi-point radiation measurements has been proposed with sensing regions in its cladding and in the area outside of the core. A part of the scintillation photons is trapped inside the fiber core and is transmitted to the end. The time of flight technique has been applied to the arrival time difference of the photons which are transmitted to each fiber end. Discrete radiation measurements were possible with a time resolution of 3nsec. Linearity of the measured counts has been demonstrated in a dose rate ranging between 4.2?Sv and 44?Sv. (author)

79

A Multi-D-Shaped Optical Fiber for Refractive Index Sensing  

Science.gov (United States)

A novel class of multi-D-shaped optical fiber suited for refractive index measurements is presented. The multi-D-shaped optical fiber was constructed by forming several D-sections in a multimode optical fiber at localized regions with femtosecond laser pulses. The total number of D-shaped zones fabricated could range from three to seven. Each D-shaped zone covered a sensor volume of 100 ?m depth, 250 ?m width, and 1 mm length. The mean roughness of the core surface obtained by the AFM images was 231.7 nm, which is relatively smooth. Results of the tensile test indicated that the fibers have sufficient mechanical strength to resist damage from further processing. The multi-D-shaped optical fiber as a high sensitive refractive-index sensor to detect changes in the surrounding refractive index was studied. The results for different concentrations of sucrose solution show that a resolution of 1.27 × 10?3–3.13 × 10?4 RIU is achieved for refractive indices in the range of 1.333 to 1.403, suggesting that the multi-D-shaped fibers are attractive for chemical, biological, and biochemical sensing with aqueous solutions. PMID:22399908

Chen, Chien-Hsing; Tsao, Tzu-Chein; Tang, Jaw-Luen; Wu, Wei-Te

2010-01-01

80

A Multi-D-Shaped Optical Fiber for Refractive Index Sensing  

Directory of Open Access Journals (Sweden)

Full Text Available A novel class of multi-D-shaped optical fiber suited for refractive index measurements is presented. The multi-D-shaped optical fiber was constructed by forming several D-sections in a multimode optical fiber at localized regions with femtosecond laser pulses. The total number of D-shaped zones fabricated could range from three to seven. Each D-shaped zone covered a sensor volume of 100 ?m depth, 250 ?m width, and 1 mm length. The mean roughness of the core surface obtained by the AFM images was 231.7 nm, which is relatively smooth. Results of the tensile test indicated that the fibers have sufficient mechanical strength to resist damage from further processing. The multi-D-shaped optical fiber as a high sensitive refractive-index sensor to detect changes in the surrounding refractive index was studied. The results for different concentrations of sucrose solution show that a resolution of 1.27 × 10?3–3.13 × 10?4 RIU is achieved for refractive indices in the range of 1.333 to 1.403, suggesting that the multi-D-shaped fibers are attractive for chemical, biological, and biochemical sensing with aqueous solutions.

Chien-Hsing Chen

2010-05-01

 
 
 
 
81

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

82

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

Science.gov (United States)

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/refractive index unit (RIU)] of this sensor for detecting changes in the bulk refractive indices has been demonstrated. The label-free affinity bio-molecules sensing capability has also been demonstrated using biotin and streptavidin as the receptor and the analyte. PMID:21412453

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

2011-01-01

83

Research and application of optical fiber sensing technology in wireless temperature monitoring of switchgear  

Science.gov (United States)

In view of the high voltage, strong magnetic field environment of high voltage switchgear, the isolation contact temperature measurement scheme of optical fiber based on wireless sensor technology realizes the contact temperature monitoring of high-voltage switchgear. In this scheme, good thermal conductivity and insulation ceramic materials are selected as outer jacket material sensing probe, and the program has a good solution to the problem of high and low voltage isolation; Combination of optical fiber composite insulator for wireless sensing, solves the problem of high voltage insulation, but also to avoid the "creeping" phenomenon due to dust. The package structure and reasonable installation solve the cross sensitivity of strain. Application shows that the precision of temperature measurement of the system can reach ± 0.5 ° and can work in a variety of harsh environment. It can improve the reliability of the operation of electrical equipment significantly and has considerable practical value for the normal operation of the whole power system.

Gan, Weibing; Zhang, Cui

2013-09-01

84

Vibration pattern recognition and classification in OTDR based distributed optical-fiber vibration sensing system  

Science.gov (United States)

In this paper we propose and demonstrate the scheme of vibration pattern recognition and classification in the OTDR based distributed optical-fiber vibration sensing system. We set up the engineering system with signal processing PC for perimeter security in some high-tech park in Nanjing. Three types of disturbing actions, including climbing up and kicking at the wall by a person, and watering on the sensing optical fiber cable same as the rain falling on, are implemented. By using level crossing rate (LCR), we can obtain their individual pattern features, so that the eigenvalue database for three disturbing actions can be built in the system. By comparing three types of vibrations, the differences among these can be given out. The results show three vibration patterns can be recognized and classified effectively.

Zhu, Hui; Pan, Chao; Sun, Xiaohan

2014-03-01

85

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

86

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

87

Seepage and settlement monitoring for earth embankment dams using fully distributed sensing along optical fibers  

Science.gov (United States)

A method for seepage and settlement monitoring in earth embankment dams using fully distributed sensing along optical fibres is proposed. A model is developed for simulating and monitoring seepage and settlement systems. This model relates the strains and the temperature changes to the fiber Brillouin gain spectrum in the embankment dam embedding the optical fiber sensors. The model consists of two parts. Submodel 1 addresses the simulation of seepage inside the embankment dam. Submodel 2 relates the measurement of the fiber Brillouin gain spectrum to the changes in temperature and strain inside the embankment dam. Both the changes in temperature and strain during the process are used to reveal serious seepages and settlements occurring inside the embankment dam. The continuously decreasing temperature curve shows an abrupt dramatic increasing rate, which shows that the change is not caused by the temperature of the seepage water but the strain. In this paper, as an example, a model filled with the soil from Yellow River is built and bare optical fibers are embedded under different soil layers near the seepage path. The simulated seepage flows under various flow rates are monitored using the optical fibers and measured by a DiTeSt -STA202 distributed temperature and strain analyzer. A partial settlement within the embankment dam model is observed.

Zhu, P. Y.; Zhou, Y.; Thévenaz, Luc; Jiang, G. L.

2008-12-01

88

Integration of large-area metallic nanohole arrays with multimode optical fibers for surface plasmon resonance sensing  

Science.gov (United States)

Here, we report an implementation of enhanced surface plasmon resonance sensing on optical fibers through integration of large-area metallic nanohole arrays on the endfaces of multimode optical fibers by a template transfer method. The Au nanohole array integrated optical fiber sensors show a high refractive index sensitivity 559 nm per refractive index unit, narrow resonant peak width less than 10 nm in aqueous solution, and consistent optical responses with peak position variation less than 0.5 nm for various core diameters of optical fibers at same dielectric conditions. These specifications demonstrates that the nanohole array based optical fibers can serve as a high-performance, portable and lensless plasmonic platform with superior robustness and accessibility for surface plasmon resonance sensing.

Jia, Peipei; Yang, Jun

2013-06-01

89

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

Directory of Open Access Journals (Sweden)

Full Text Available 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 detect a quantity; thus, FLRD is referred to as a time-domain sensing technique. FLRD sensors have near real-time response, multi-pass enhanced high-sensitivity, and relatively low cost (i.e., without using an optical spectral analyzer. During the last eight years since the introduction of the original form of fiber ringdown spectroscopy, there has been increasing interest in the FLRD technique in fiber optic sensor developments, and new application potential is being explored. This paper first discusses the challenging issues in development of multi-function, fiber optic sensors or sensor networks using current fiber optic sensor sensing schemes, and then gives a review on current fiber optic sensor development using FLRD technique. Finally, design perspectives on new generation, multi-function, fiber optic sensor platforms using FLRD technique are particularly presented.

Chuji Wang

2009-09-01

90

Optical fiber Bragg grating used in the sensing of surface plasmon resonance  

Science.gov (United States)

We introduce two types of optical fiber Bragg grating sensor with nanoscale spatial resolution and chemical specificity. This sensing technique holds promise for gaining deeper insight into the functionality of nanoscale structures superposed on the gold thin film or embedded in its complex environments. The techniques are based on the effect of surface plasmon resonance and surface plasmon resonance fluorescence. Properly p-polarized laser light illuminates the Bragg grating and induces a strongly enhanced field at the gold thin film. This is due to the coupling of guided mode of the optical fiber and surface plasmon mode. The laboratory prototype of sensor with linear Bragg grating is used for the measurement of smooth variances in refractive index and a sensor with oblique Bragg grating combined with the Scanning near field optical microscope is used for the measurement of analyte thickness. Here, the spatial resolution is determined by the tip size (typically on the order of 60-80 nm).

Tománek, Pavel; Grmela, Lubomír; Škarvada, Pavel

2007-10-01

91

Mechanism analysis on biofouling detection based on optical fiber sensing technique  

Science.gov (United States)

More attention is paid to on-line monitoring of biofouling in industrial water process systems. Based on optical fiber sensing technology, biofouling detection mechanism is put forward in the paper. With biofouling formation, optical characteristics and the relation between light intensity and refractive index studied, schematic diagram of optical fiber self-referencing detecting system and technological flowchart are presented. Immunity to electromagnetic interference and other influencing factors by which the precision is great improved is also remarkable characteristic. Absorption spectrum of fluid medium molecule is measured by infrared spectrum and impurity is analyzed by character fingerprints of different liquid. Other pollutant source can be identified by means of infrared spectrum and arithmetic research of artificial neural networks (ANN) technology. It can be used in other fields such as mining, environment protection, medical treatment and transportation of oil, gas and water.

Ma, Huiping; Yuan, Feng; Liu, Yongmeng; Jiang, Xiuzhen

2010-08-01

92

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

93

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

94

A Self-Referencing Intensity-Based Fiber Optic Sensor with Multipoint Sensing Characteristics  

Directory of Open Access Journals (Sweden)

Full Text Available A self-referencing, intensity-based fiber optic sensor (FOS is proposed and demonstrated. The theoretical analysis for the proposed design is given, and the validity of the theoretical analysis is confirmed via experiments. We define the measurement parameter, X, and the calibration factor, ?, to find the transfer function, , of the intensity-based FOS head. The self-referencing and multipoint sensing characteristics of the proposed system are validated by showing the measured  and relative error versus the optical power attenuation of the sensor head for four cases: optical source fluctuation, various remote sensing point distances, fiber Bragg gratings (FBGs with different characteristics, and multiple sensor heads with cascade and/or parallel forms. The power-budget analysis and limitations of the measurement rates are discussed, and the measurement results of fiber-reinforced plastic (FRP coupon strain using the proposed FOS are given as an actual measurement. The proposed FOS has several benefits, including a self-referencing characteristic, the flexibility to determine FBGs, and a simple structure in terms of the number of devices and measuring procedure.

Sang-Jin Choi

2014-07-01

95

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

96

E-beam patterned gold nanodot arrays on optical fiber tips for localized surface plasmon resonance biochemical sensing.  

Science.gov (United States)

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. PMID:22163415

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

2010-01-01

97

Immobilization of a calcein derivative onto optical fibers for calcium ion sensing  

Science.gov (United States)

This paper describes a new fiber-optic calcium ion sensor using the calcein derivative, calcein acrylamide. Calcein acrylamide (CA) is a fluorescent indicator with a sensitivity for calcium ions at pH greater than 10. Ca2+ binds with CA with a binding ratio of 2:1 ratio therefore the concentration range for Ca2+ sensing depends on the amount of indicator present. Typically, calcium can be detected in the range 0 to 20 micrometers ol 1-1. The indicator can be covalently immobilized within a polymer matrix which itself is covalently immobilized onto a chemically modified optical fiber using photo-initiated polymerization. Three Ca2+ sensitive polymers are presented; CA in (1) poly-hydroxyethyl methacrylate (poly- HEMA), (2) poly-acrylamide and (3) poly-N-vinyl-pyrrolidinone (n-VP). The sensitivity of the immobilized CA are similar to that of CA in free solution.

Sloan, William D.; Uttamlal, Mahesh

1999-12-01

98

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

99

Application of optical fiber sensing technique to fast breeder reactor plants  

International Nuclear Information System (INIS)

Optical fiber thermometers have some characteristics such as non-induction for electromagnetic interference noises, capability of measuring continuous temperature distribution ranging to even some km along the fiber by differing from conventional electric spot-type sensors such as thermocouple, and so on, so it can be expected to largely contribute to safety and reliability from viewpoints of monitoring and maintenance of plants, by applying the characteristics to temperature measurements of apparatuses and pipings in a fast breeder reactor (FBR) plant. As temperature measuring technology using optical fibers is already practiced at fire detection of buildings, tunnels, and so on, because of increasing transmission loss based on effects of radiation when using at nuclear reactor plants, it is important to adequately compensate this increase. Here was introduced an R and D result to make practice on temperature and radiation measuring methods at radiation environment, by applying optical fiber sensing technique to the fast breeder test-reactor, 'Joyo' of a sodium cooling-type FBR of JNC. (G.K.)

100

Study of sensing properties and contrastive analysis of metal coating optical fiber grating  

Science.gov (United States)

Optical fiber grating (FBG) has been widely used in the measurement of parameters such as temperature and strain. However, FBG is too slim to broken, whose outside protective layer tends to shedding easily, and it is also hard to change the temperature and strain sensitivity. In order to overcome the above disadvantages and to further expand the application range of FBG, this paper improves the technology of fiber grating metal film plating process firstly. It adopts a compositive method including chemical plating and electroplating to gild FBG, copper FBG and galvanize FBG, which all get good metal coating. Then, the temperature and strain sensing properties of metalized FBG is studied in detail. Multiple metal coating FBGs were put in high-low temperature test-box together, and then the test-box worked continuously at the temperature range of 0°C?95°C. After several experiments, it concludes that metal plating enhances the temperature sensitivity of fiber grating, and the one with galvanization has the highest temperature sensitivity of 0.0235. At last, FBGs with various cladding were pasted on carbon fiber cantilever beam respectively and the pressure on the top of the cantilever increased gradually. The experimental results show that wavelength of fiber grating shift toward the long wavelength with the increase of the pressure, and the one with galvanization has the maximum strain sensitivity which has minimal impact on fiber properties.

Wang, Jing; Wang, Ning; Shi, Bin; Sui, Qingmei; Guan, Congsheng; Wei, Guangqing; Li, Shuhua

2014-02-01

 
 
 
 
101

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

102

Fiber Optics  

Science.gov (United States)

SFGate: SBC and Microsofthttp://sfgate.com/cgi-bin/article.cgi?file=/c/a/2004/06/23/MNGVR7AI711.DTLSBC Communications Inc.http://www.sbc.com/gen/press-room?pid=5838How Stuff Works: How Fiber Optics Workhttp://electronics.howstuffworks.com/fiber-optic.htmFiber Optic Reference Guide: A Brief Historyhttp://www.fiber-optics.info/fiber-history.htmPC World: Has Your Broadband Had Its Fiber?http://www.pcworld.com/news/article/0,aid,117684,00.aspTelephony Onlinehttp://telephonyonline.com/ar/telecom_breaking_meg_barrier/index.htmThis article from SFGate reports on the recent negotiations between SBC and Microsoft (1) and the implications of the new technology for Internet and television access. This website from SBC (2) provides video footage and background information on their initiative called Project Lightspeed. This initiative is based largely on fiber technology, which is described further on this website from How Stuff Works (3). This website (4) provides a brief history of fiber optics technology along with links to sections on the applications of fiber optics and more basics on transmission. This article from PC World (5) discusses how fiber optics became a viable option. This article from Telephony Online 6)reviews some of the challenges that remain.

103

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

Science.gov (United States)

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.

Lee, Hyeonseok; Park, Hyun-Jun; Sohn, Hoon; Kwon, Il-Bum

2010-10-01

104

Fiber optic sensing system for in-situ simultaneous monitoring of water stage, quality, and temperature  

Science.gov (United States)

To accurately track the water stage changes and environmental influences on water quality and have sufficient follow-ups to prevent potential flood and environmental hazards, an in-situ continuous monitoring system for water stage and quality is helpful. Traditional in-situ water-stage monitoring system has relative low accuracy and require separate sensors for water quality and temperature which complex the evaluation. Advanced optical fiber sensors, with unique features of real-time and multiparameter sensing capacity, could provide potential simultaneous evaluation of flooding, water-quality deterioration, and science-based decision support. In this study, an in-situ monitoring system for water stage, overall water quality, and temperature is developed using long-period fiber grating (LPFG) sensors. When part of the LPFG sensor is submerged in water, the resonant wavelength of each cladding mode of the LPFG sensor varies linearly with the submerged length (refer to water stage) and temperature, and nonlinearly with refractive index changes (referred to the water quality). Two resonant wavelengths were used to relate the water stage and overall water quality to the change in resonant wavelengths of the LPFG sensor. Sharing the same fiber line, one sequential glass packaged LPFG was used to monitor the temperature changes at the same location. The algorithm for simultaneous determination of the water stage, overall water quality, and temperature was analytically formulated and experimentally validated. Benefit from the multi-parameter sensing using one single fiber line, the developed optical sensing network can potentially provide a low-cost, real-time, and high resolution solution for the in-situ water quality monitoring.

Huang, Ying

2014-04-01

105

Temperature sensing in high voltage transmission lines using fiber Bragg grating and free-space-optics  

Science.gov (United States)

In this work we proposed the use of free-space-optics (FSO) to transmit and receive the optical signals from optical fiber placed in ground potential to the FBG fiber optics at high voltage potential, using a pair of optical collimators. The technique evaluation was performed in a prototype for the study of sensitivity to optical alignment and in an external environment using emulated sensing systems for both bus bar and overhead transmission line with real isolator chain. It has been shown that the FSO system allows collimators operate at distances of 500 mm to 2.000 mm. This range of distances is similar to the length of insulator's chain up to 230 kV. It was also shown that the proposed system can be used in real external environment for bus bar temperature monitoring in substations, where, even if the time out of the system is of 45%, with major interruption time of almost 15 hours, the majority of the interruption time was less than 18 minutes long. On the other hand, system has to be improved in order to be used in overhead transmission line. As tested for a real isolator chain the system shown a time out of 80.3%, with significant number of events of interruption acquisition time greater than 150 minutes. It is believed that for overhead power lines, system must be installed in rigid surge arresters or in a line post where it is expected to have similar results as in substation bus bars monitoring.

Floridia, Claudio; Rosolem, Joao B.; Leonardi, Ariovaldo A.; Hortencio, Claudio A.; Fonseca, Romeu F.; Moreira, Rodrigo O. C.; Souza, Giovani C. L.; Melo, Altair L.; Nascimento, Carlos A. M.

2013-05-01

106

A novel microbending hetero-core fiber optic sensor for force and location sensing with applications to home security  

Science.gov (United States)

In this paper, a novel design of microbending hetero-core fiber optic sensor for force and location sensing is proposed, and potential applications to home security systems are discussed. Force and location detection is done by using two different microbending fiber optic sensors. The main idea is, we have two unknowns, two different fibers, and two simultaneous intensity measurements. In order to demonstrate the location detection of the microbending fiber optic sensor, changes in the light intensity are examined with different force locations and forces magnitudes on the microbending fiber optic sensor. Several experiments are performed for different microbend sensors by varying periodicity, corrugation size, thickness of plates, and the configuration of optical fiber type. All experiments were done on a microbending sensor constructed from 62,5/125 ?m multimode fibers and a microbending sensor constructed from 62,5-50-62,5/125 ?m hetero-core fiber. For each case, the output light intensity is measured as a function of applied force. The characteristics of hysteresis, repeatability and location comparison are examined for each combination of microbending fiber optic sensors. Experimental results show that the sensitivity of the proposed microbending sensor constructed using hetero-core optical fiber having loops is the highest.

Likoglu, Sumeyra; Alemdar, Kubra; Fidanboylu, Kemal; Toker, Onur

2014-03-01

107

Optical sensing elements for nitrogen dioxide (NO.sub.2) gas detection, a sol-gel method for making the sensing elements and fiber optic sensors incorporating nitrogen dioxide gas optical sensing elements  

Science.gov (United States)

A sensing element, a method of making a sensing element, and a fiber optic sensor incorporating the sensing element are described. The sensor can be used for the quantitative detection of NO.sub.2 in a mixture of gases. The sensing element can be made by incorporating a diazotizing reagent which reacts with nitrous ions to produce a diazo compound and a coupling reagent which couples with the diazo compound to produce an azo dye into a sol and allowing the sol to form an optically transparent gel. The sensing element changes color in the presence of NO.sub.2 gas. The temporal response of the absorption spectrum at various NO.sub.2 concentrations has also been recorded and analyzed. Sensors having different design configurations are described. The sensing element can detect NO.sub.2 gas at levels of parts per billion.

Mechery, Shelly John (Mississippi State, MS); Singh, Jagdish P. (Starkville, MS)

2007-07-03

108

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

109

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

110

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

111

An ameliorative technique for distributed Brillouin-based fiber optics sensing  

Science.gov (United States)

This paper reports an ameliorative technique for distributed fiber optics sensing based on Brillouin optical time-domain reflectometry (BOTDR) and Brillouin optical-fiber time-domain analysis (BOTDA). Because the electro-optic modulator in BOTDR system has a finite extinction ratio, the pulsed laser always contains a CW component, which is hereafter called leakage. The frequency of the leakage is pv which is the same as that of the pulse, and the frequency of the Stokes wave is sv. The frequency of the acoustic wave bv at each point along the fiber matches the beat frequency of the leakage and the Stokes wave. As a result, when given an appropriate extinction ratio, the leakage will have a biggish effect on the Stokes wave, which is the same as the function between the continuous wave and the Stokes in BOTDA system. The Stokes component in spontaneous Brillouin scattering (SPBS) is amplified by the leakage along the distance when it backs to the laser end, which is the well known stimulated Brillouin scattering (SBS) phenomena. So long as the distance from the point where the SPBS engender to the laser end is long, the intensity of the SBS signal is relatively large owing to the longer amplified interval. In BOTDR system, when setting the extinction ratio at 20dB, using the SBS signal we can achieve a SNR which is approximately 5 dB greater than that of traditional system and the dynamic range performance 3 dB greater. Utilizing this new technique in BOTDR system it also has an ascendency compared with BOTDA system in respect that it access to only one end of the fiber with probe pulse light.

Yang, Xing-hong; Li, Yong-qian; Yang, Zhi; Yoshino, Toshihiko

2008-12-01

112

Optical Fiber Networks for Remote Fiber Optic Sensors  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

113

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 (10-8??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

114

High-spatial-resolution temperature monitoring of an industrial motor using a distributed fiber optic sensing technique  

Science.gov (United States)

We report the use of a fiber-optic distributed sensing system to monitor temperature at a multitude of discrete points on an industrial motor undergoing qualification after a rewinding. This technique involves using optical frequency domain reflectometry to demodulate the reflected signal from multiplexed Bragg gratings that have been photoetched in the core of an optical fiber. In this work, high-resolution optical sensing fiber was applied along the stator windings and end-windings of the motor to assess their suitability for long-term temperature monitoring. Performance tests were conducted at different heat loads representing different electrical conditions. Results indicate excellent agreement with collocated Resistance Temperature Devices (RTDs) and demonstrate significant potential for mitigating costly motor failure due to insulation breakdown resulting from highly localized hotspots.

Duncan, Roger G.; Childers, Brooks A.; Rajendran, Veera

2004-07-01

115

Selective deep wet etching of fused silica optical fibers for sensing applications  

Science.gov (United States)

In the paper we discuss crucial aspects of selective deep wet etching technology of fused silica optical fibers. The technology includes preparation of the fiber, photolithography aiming to create a mask for etching, wet etching process and photoresist removal. We also discuss the influence of removing polyimide layer from the fiber, photoresist type, thickness of the photoresist and etching time. The developed technology allows for obtaining periodic variations in the fiber diameter resulting in formation of corrugated long-period grating (LPG). Introduction of strain induces appearing of attenuation peak in the transmission spectrum of the fiber. The developed technology can be also applied for fabrication of other optical fiber devices.

Krogulski, Krzysztof; ?mietana, Mateusz; Kwietniewski, Norbert; Król, Krystian

2013-07-01

116

A Hybrid Highly Birefringent Fiber Optic Sensing System for Simultaneous Strain and Temperature Measurement  

Digital Repository Infrastructure Vision for European Research (DRIVER)

A novel hybrid fiber optic sensor based on integration of polarimetric fiber sensors for simultaneous strain and temperature measurement is presented in this paper. Two types of polarimetric fibers are used: a side-hole fiber and a polarization maintaining photonic crystal fiber. The disadvantage of each sensor type can be overcome by using the sensors in a complementary manner to measure temperature independently from average strain.

Lesiak, Piotr; Rajan, Ginu; Semenova, Yuliya; Farrell, Gerald; Boczkowska, Anna; Domanski, Andrzej; Wolinkski, Tomasz

2010-01-01

117

Fiber Optics  

Science.gov (United States)

Optical fibers transmit light signals and are widely used in the telecommunications industry to transmit data over long distances. Light travels through the core material of an optical fiber by essentially repeatedly bouncing off the cladding material that surrounds the core. Understanding refraction and how light behaves at the boundary of two different materials is the basis for understanding how fiber optic lines work. In particular, total internal reflection occurs when light travels in a material with a higher index of refraction toward a material with a lower index of refraction and the angle of incidence is greater than the critical angle.In this lesson, students investigate through experimentation, discussion, and video the phenomenon of total internal reflection and its relationship to fiber optics. Students also watch a video about dispersion and discuss the implications for fiber optics.Note: This is the second of two optics lesson plans. You may want to precede this lesson with The Index of Refraction Lesson Plan.

2012-05-24

118

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

119

Research on fully distributed optical fiber sensing security system localization algorithm  

Science.gov (United States)

A new fully distributed optical fiber sensing and location technology based on the Mach-Zehnder interferometers is studied. In this security system, a new climbing point locating algorithm based on short-time average zero-crossing rate is presented. By calculating the zero-crossing rates of the multiple grouped data separately, it not only utilizes the advantages of the frequency analysis method to determine the most effective data group more accurately, but also meets the requirement of the real-time monitoring system. Supplemented with short-term energy calculation group signal, the most effective data group can be quickly picked out. Finally, the accurate location of the climbing point can be effectively achieved through the cross-correlation localization algorithm. The experimental results show that the proposed algorithm can realize the accurate location of the climbing point and meanwhile the outside interference noise of the non-climbing behavior can be effectively filtered out.

Wu, Xu; Hou, Jiacheng; Liu, Kun; Liu, Tiegen

2013-12-01

120

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

 
 
 
 
121

Fiber optic moisture sensor  

Science.gov (United States)

A method and apparatus for sensing moisture changes by utilizing optical fiber technology. One embodiment uses a reflective target at the end of an optical fiber. The reflectance of the target varies with its moisture content and can be detected by a remote unit at the opposite end of the fiber. A second embodiment utilizes changes in light loss along the fiber length. This can be attributed to changes in reflectance of cladding material as a function of its moisture content. It can also be affected by holes or inserts interposed in the cladding material and/or fiber. Changing light levels can also be coupled from one fiber to another in an assembly of fibers as a function of varying moisture content in their overlapping lengths of cladding material.

Kirkham, R.R.

1984-08-03

122

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

123

Design and test research of a new optical fiber F-P humidity sensing system for modern agriculture environmental monitor  

Science.gov (United States)

Humidity monitoring is more and more emphasized on agriculture. Optical fiber humidity sensor has been paid great attention based on its excellent properties. In this paper, a novel method for the optic fiber F-P sensors based on the optimum double wavelength stabilization technique is put forward to use in humidity monitoring. The controlling system of work point which used for sensor stabilization is designed. DE algorithm stabilization model of sensing system is established. The working wavelength of DWDM and length of F-P cavity are calculated by the DE optimization design method. A sensing system with higher orthogonal precision is designed. The experimental setup of light route test is established. The results show that the light route performance of sensing system is well. This stabilization method is totally passive and offers a high resolution. It can satisfy the stabilization need of optical fiber F-P humidity sensor working point. DE algorithm can be used for the structural optimization design of optical fiber F-P humidity sensor.

Shan, Ning; Liu, Xia; Wang, Shaohua

124

Shape sensing using multi-core fiber optic cable and parametric curve solutions.  

Science.gov (United States)

The shape of a multi-core optical fiber is calculated by numerically solving a set of Frenet-Serret equations describing the path of the fiber in three dimensions. Included in the Frenet-Serret equations are curvature and bending direction functions derived from distributed fiber Bragg grating strain measurements in each core. The method offers advantages over prior art in that it determines complex three-dimensional fiber shape as a continuous parametric solution rather than an integrated series of discrete planar bends. Results and error analysis of the method using a tri-core optical fiber is presented. Maximum error expressed as a percentage of fiber length was found to be 7.2%. PMID:22330534

Moore, Jason P; Rogge, Matthew D

2012-01-30

125

Fiber optical tweezers for microscale and nanoscale particle manipulation and force sensing  

Science.gov (United States)

Optical tweezers have been an important tool in biology and physics for studying single molecules and colloidal systems. Most of current optical tweezers are built with microscope objectives, which are: i) expensive, ii) bulky and hard to integrate, iii) sensitive to environmental fluctuations, iv) limited in terms of working distances from the substrate, and v) rigid with the requirements on the substrate (transparent substrate made with glass and with a fixed thickness). These limitations of objective-based optical tweezers prevent them from being miniaturized. Fiber optical tweezers can provide a solution for cost reduction and miniaturization, and these optical tweezers can be potentially used in microfluidic systems. However, the existing fiber optical tweezers have the following limitations: i) low trapping efficiency due to weakly focused beams, ii) lack of the ability to control the positions of multiple particles simultaneously, and iii) limited functionalities. The overall objective of this dissertation work is to further the fundamental understanding of fiber optical tweezers through experimental study and modeling, and to develop novel fiber optical tweezers systems to enhance the capability and functionalities of fiber optical tweezers as microscale and nanoscale manipulators/sensors. The contributions of this dissertation work are summarized as follows. i) An enhanced understanding of the inclined dual-fiber optical tweezers (DFOTs) system has been achieved. Stable three dimensional (3D) optical trapping of a single micron-sized particle has been experimentally demonstrated. This is the first time that the trapping efficiency has been calibrated and the stiffness of the trap has been obtained in the experiments, which has been carried out by using two methods: the drag force method and power spectrum analysis. Such calibration enables the system to be used as a picoNewton-level force sensor in addition to a particle manipulator. The influence of system parameters on the trapping performance has been carefully investigated through both experimental and numerical studies. ii) Multiple traps have been created and carefully studied with the inclined DFOTs for the first time. Three traps, one 3D trap and two 2D traps, have been experimentally created at different vertical levels with adjustable separations and positions. iii) Multiple functionalities have been achieved and studied for the first time with the inclined DFOTs. Particle separation, grouping, stacking, rod alignment, rod rotation, and optical binding have been experimentally demonstrated. The multiple functionalities allow the inclined DFOTs to find applications in the study of interaction forces in colloidal systems as well as parallel particle manipulation in drug delivery systems. iv) Far-field superfocusing effect has been investigated and successfully demonstrated with a fiber-based surface plasmonic (SP) lens for the first time. A planar SP lens with a set of concentric nanoscale rings on a fiber endface has been developed. For the first time, a focus size that is comparable to the smallest achievable focus size of high NA objective lenses has been achieved with the fiber-based SP lens. The fiber-based SP lens can bridge the nanoscale particles/systems and the macroscale power sources/detectors, which has been a long standing challenge for nanophotonics. In addition to optical trapping, the fiber-based SP lens will impact many applications including high-resolution lithography, high-resolution fluorescence detection, and sub-wavelength imaging. v) Trapping ability enhanced with the fiber-based SP lens has been successfully demonstrated. With the help of the fiber-based SP lens, the trapping efficiency of fiber optical tweezers has been significantly enhanced, which is comparable with that of objective-based optical tweezers. A submicron-sized bacterium has been successfully trapped in three dimensions for the first time with optical tweezers based on single fibers.

Liu, Yuxiang

126

Reflectance response of tapered optical fiber coated with graphene oxide nanostructured thin film for aqueous ethanol sensing  

Science.gov (United States)

In this work, optical sensing performance of tapered multimode fiber tip coated with graphene oxide (GO) nanostructured thin film towards aqueous ethanol with different concentrations is investigated. The tapering process of the optical fiber is done by a glass processing machine. The multimode optical fiber tip is dip-coated with GO and annealed at 70 °C to enhance the binding of the nanomaterials to the silica fiber. FESEM, Raman microscopy and XRD analyses are performed to micro-characterize the GO thin films. The morphology of the GO is observed to be in sheets forms. The reflectance response of the GO coated fiber tip is compared with the uncoated tip. The measurements are taken using a spectrophotometer in the optical wavelength range of 550-720 nm. The reflectance response of the GO coated fiber tip reduced proportionally, upon exposure to ethanol with concentration range of 5-80%. The dynamic response of the developed sensor showed strong reversibility and repeatability when it is exposed to ethanol with concentrations of 5%, 20% and 40% in distilled water. At room temperature, the sensor shows fast response and recovery as low as 19 and 25 s, respectively.

Shabaneh, A. A.; Girei, S. H.; Arasu, P. T.; Rahman, W. B. W. A.; Bakar, A. A. A.; Sadek, A. Z.; Lim, H. N.; Huang, N. M.; Yaacob, M. H.

2014-11-01

127

Analysis of Faraday effect in multimode tellurite glass optical fiber for magneto-optical sensing and monitoring applications.  

Science.gov (United States)

The design and fabrication of a tellurite glass multimode optical fiber for magneto-optical applications are presented and discussed. The analysis of the polarization shows that an optical beam, linearly polarized at the fiber input, changes to elliptically polarized with an ellipticity of 1?4.5 after propagating down the fiber. However, the elliptical distribution remains unchanged with or without an applied magnetic field, demonstrating that no circular dichroism occurs within the fiber. The Verdet constant of the tellurite glass in the fiber is measured to be 28±0.5??rad·(T·m)-1, diverging by less than 3% from the Verdet constant found on the same glass composition in bulk form. These results demonstrate the feasibility to develop reliable tellurite glass fibers by the preform drawing method for magneto-optical applications. PMID:22772128

Shiyu, Yin; Lousteau, Joris; Olivero, Massimo; Merlo, Marco; Boetti, Nadia; Abrate, Silvio; Chen, Qiuling; Chen, Qiuping; Milanese, Daniel

2012-07-01

128

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

Directory of Open Access Journals (Sweden)

Full Text Available 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 fiber and their optical spectrum.

Karra. Sony*, Soumya. M

2013-03-01

129

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

130

Thymol blue immobilized on tapered fibers as optical transducer for pH sensing  

Science.gov (United States)

The present work is concerned with the optical characterization of an evanescent wave sensor for pH detection. First, the interaction between the solution containing the acid-base indicator and the fiber core was investigated. Then, the acid-base indicator, thymol blue, was covalently immobilized on the core of a 200/380 micrometers fiber by means of a silylation process of the glass surface. The fiber core surface was modified along a section of 8 mm. A comparison was made using both bare and tapered fibers, with a tapering ratio (fiber diameter/waist diameter) of 2.3. An enhancement in sensitivity of a factor 6 was observed with tapered fibers in the 1/2.5 range, and a sensitivity of 0.05 pH units was attained.

Baldini, Francesco; Ciaccheri, Leonardo; Falai, Alida; Mignani, Anna G.; Rayss, Jan; Sudolski, Grzegorz

1999-02-01

131

Distributed Fiber-Optic Sensing and Numerical Simulation of Shock Wave Response of Manufactured Clay. Phase 2: Software Model and Breadboard.  

Science.gov (United States)

The main objective of the proposed work was to determine the efficacy of distributed fiber-optic sensing in the form of Brillouin Optical Time Domain Reflectometry/Analysis (BOTDR/BOTDA) and/or fiber Bragg grating (FBG) application to measure and model th...

M. A. Mentzer

2013-01-01

132

Distributed Fiber-Optic Sensing and Numerical Simulation of Shock Wave Response of Manufactured Clay. Phase 3: Breadboard and Technology Transfer.  

Science.gov (United States)

The main objective of the proposed work is to determine the efficacy of distributed fiber-optic sensing in the form of Brillouin Optical Time Domain Reflectometry/Analysis (BOTDR/BOTDA) and/or fiber Bragg grating (FBG) application to measure and model the...

M. A. Mentzer

2013-01-01

133

Distributed Fiber-Optic Sensing and Numerical Simulation of Shock Wave Response of Manufactured Clay. Phase 3. Breadboard and Technology Transfer.  

Science.gov (United States)

The main objective of the proposed work is to determine the efficacy of distributed fiber-optic sensing in the form of Brillouin Optical Time Domain Reflectometry/Analysis (BOTDR/BOTDA) and/or fiber Bragg grating (FBG) application to measure and model the...

M. A. Mentzer

2013-01-01

134

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

135

Optical Fiber Networks for Remote Fiber Optic Sensors  

Directory of Open Access Journals (Sweden)

Full Text Available 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, pros and cons. Finally, a synopsis of the main factors to take into consideration in the design of a remote sensor system is gathered.

Montserrat Fernandez-Vallejo

2012-03-01

136

Optical Fiber Networks for Remote Fiber Optic Sensors  

Science.gov (United States)

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, pros and cons. Finally, a synopsis of the main factors to take into consideration in the design of a remote sensor system is gathered. PMID:22666011

Fernandez-Vallejo, Montserrat; Lopez-Amo, Manuel

2012-01-01

137

Simple fiber-optic technique for in-situ corrosion sensing in structures  

Science.gov (United States)

Corrosion of structures is a serious problem involving man and material safety. Over the years, though several methods of monitoring corrosion have been devised with some success, but there is a persistent need for devising non-destructive and in-situ techniques for monitoring corrosion in structures. Fiber optic techniques are capable of meeting these requirements, besides offering several other important advantages. Fiber optic corrosion sensors have thus become quite attractive and are currently being investigated to address the high costs associated with the existing structural maintenance procedures. Fiber optics based direct absorption spectroscopic techniques investigated by some groups for estimating corrosion have used single fiber elements for recording the signal reflected from specimen at different wavelengths. As the light coupling efficiency of the single fiber elements is relatively poor in comparison with that of fiber bundles and the signal available for processing is weak, the paper presents a simple and alternate technique based on the color matching principle of fiber optic colorimetry to detect corrosion induced color changes. It employs a thin Y- shaped fiber optic bundle which increases the quantity of light energy coupled from a whitelight source. The light reflected off the sample is made incident on a PIN photo- detector through a complementary filter. A series of such probes can be safety embedded and or bonded to structures at pre-determined locations. The experimental set up for this sensor was implemented and feasibility of in-situ corrosion detection in structures demonstrated. Measurement data was acquired for steel samples corroded both in concrete embedded and open ambience conditions and results analyzed.

Singh, Nahar; Jain, Subhash C.; Aggarwal, Anil K.; Singla, Madan L.; Singh, Mewa

2000-05-01

138

Fiber optic fluid detector  

Science.gov (United States)

Particular gases or liquids are detected with a fiber optic element (11, 11a to 11j) having a cladding or coating of a material (23, 23a to 23j) which absorbs the fluid or fluids and which exhibits a change of an optical property, such as index of refraction, light transmissiveness or fluoresence emission, for example, in response to absorption of the fluid. The fluid is sensed by directing light into the fiber optic element and detecting changes in the light, such as exit angle changes for example, that result from the changed optical property of the coating material. The fluid detector (24, 24a to 24j) may be used for such purposes as sensing toxic or explosive gases in the atmosphere, measuring ground water contamination or monitoring fluid flows in industrial processes, among other uses.

Angel, S. Michael (Livermore, CA)

1989-01-01

139

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

140

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

 
 
 
 
141

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

142

Optical fiber evanescent absorption sensors for high-temperature gas sensing in advanced coal-fired power plants  

Science.gov (United States)

Modern advanced energy systems such as coal-fired power plants, gasifiers, or similar infrastructure present some of the most challenging harsh environments for sensors. The power industry would benefit from new, ultra-high temperature devices capable of surviving in hot and corrosive environments for embedded sensing at the highest value locations. For these applications, we are currently exploring optical fiber evanescent wave absorption spectroscopy (EWAS) based sensors consisting of high temperature core materials integrated with novel high temperature gas sensitive cladding materials. Mathematical simulations can be used to assist in sensor development efforts, and we describe a simulation code that assumes a single thick cladding layer with gas sensitive optical constants. Recent work has demonstrated that Au nanoparticle-incorporated metal oxides show a potentially useful response for high temperature optical gas sensing applications through the sensitivity of the localized surface plasmon resonance absorption peak to ambient atmospheric conditions. Hence, the simulation code has been applied to understand how such a response can be exploited in an optical fiber based EWAS sensor configuration. We demonstrate that interrogation can be used to optimize the sensing response in such materials.

Buric, Michael P.; Ohodnicky, Paul R.; Duy, Janice

2012-10-01

143

Optical fiber evanescent wave adsorption sensors for high-temperature gas sensing in advanced coal-fired power plants  

Energy Technology Data Exchange (ETDEWEB)

Modern advanced energy systems such as coal-fired power plants, gasifiers, or similar infrastructure present some of the most challenging harsh environments for sensors. The power industry would benefit from new, ultra-high temperature devices capable of surviving in hot and corrosive environments for embedded sensing at the highest value locations. For these applications, we are currently exploring optical fiber evanescent wave absorption spectroscopy (EWAS) based sensors consisting of high temperature core materials integrated with novel high temperature gas sensitive cladding materials. Mathematical simulations can be used to assist in sensor development efforts, and we describe a simulation code that assumes a single thick cladding layer with gas sensitive optical constants. Recent work has demonstrated that Au nanoparticle-incorporated metal oxides show a potentially useful response for high temperature optical gas sensing applications through the sensitivity of the localized surface plasmon resonance absorption peak to ambient atmospheric conditions. Hence, the simulation code has been applied to understand how such a response can be exploited in an optical fiber based EWAS sensor configuration. We demonstrate that interrogation can be used to optimize the sensing response in such materials.

Buric, M.; Ohodnicky, P.; Duy, J.

2012-01-01

144

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

145

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

146

Optical Fiber Chemical Sensor with Sol-Gel Derived Refractive Material as Transducer for High Temperature Gas Sensing in Clean Coal Technology  

Energy Technology Data Exchange (ETDEWEB)

The chemistry of sol-gel derived silica and refractive metal oxide has been systematically studied. Sol-gel processes have been developed for preparing porous silica and semiconductor metal oxide materials. Micelle/reversed micelle techniques have been developed for preparing nanometer sized semiconductor metal oxides and noble metal particles. Techniques for doping metal ions, metal oxides and nanosized metal particles into porous sol-gel material have also been developed. Optical properties of sol-gel derived materials in ambient and high temperature gases have been studied by using fiber optic spectroscopic techniques, such as fiber optic ultraviolet/visible absorption spectrometry, fiber optic near infrared absorption spectrometry and fiber optic fluorescence spectrometry. Fiber optic spectrometric techniques have been developed for investigating the optical properties of these sol-gel derived materials prepared as porous optical fibers or as coatings on the surface of silica optical fibers. Optical and electron microscopic techniques have been used to observe the microstructure, such as pore size, pore shape, sensing agent distribution, of sol-gel derived material, as well as the size and morphology of nanometer metal particle doped in sol-gel derived porous silica, the nature of coating of sol-gel derived materials on silica optical fiber surface. In addition, the chemical reactions of metal ion, nanostructured semiconductor metal oxides and nanometer sized metal particles with gas components at room temperature and high temperatures have also been investigated with fiber optic spectrometric methods. Three classes of fiber optic sensors have been developed based on the thorough investigation of sol-gel chemistry and sol-gel derived materials. The first group of fiber optic sensors uses porous silica optical fibers doped with metal ions or metal oxide as transducers for sensing trace NH{sub 3} and H{sub 2}S in high temperature gas samples. The second group of fiber optic sensors uses sol-gel derived porous silica materials doped with nanometer particles of noble metals in the form of fiber or coating for sensing trace H{sub 2}, NH{sub 3} and HCl in gas samples at for applications ambient temperature. The third classes of fiber optic sensors use sol-gel derived semiconductor metal oxide coating on the surface of silica optical fiber as transducers for selectively sensing H{sub 2}, CH{sub 4} and CO at high temperature. In addition, optical fiber temperature sensors use the fluorescence signal of rare-earth metal ions doped porous silica optical fiber or the optical absorption signal of thermochromic metal oxide materials coated on the surface of silica optical fibers have also been developed for monitoring gas temperature of corrosive gas. Based on the results obtained from this project, the principle of fiber optic sensor techniques for monitoring matrix gas components as well as trace components of coal gasification derived syngas has been established. Prototype sensors for sensing trace ammonia and hydrogen sulfide in gasification derived syngas have been built up in our laboratory and have been tested using gas samples with matrix gas composition similar to that of gasification derived fuel gas. Test results illustrated the feasibility of these sensors for applications in IGCC processes.

Shiquan Tao

2006-12-31

147

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

148

Optical fibre sensing of plasmas  

Energy Technology Data Exchange (ETDEWEB)

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)

Woolsey, G.A.; Scelsi, G.B. [School of Physical Sciences and Engineering, Univ. of New England, Armidale, NSW (Australia)

2000-03-01

149

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)

150

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

151

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

152

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

153

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

154

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)

155

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.

156

Optical fiber-tip Fabry-Perot interferometer for hydrogen sensing  

Science.gov (United States)

A novel optical fiber-tip Fabry-Perot interferometer (FPI) coated with Pt/WO3 film was demonstrated as a hydrogen sensor. The air-cavity of FPI was formed by inserting a single mode fiber (SMF) into a partially polymer-filled glass capillary. A layer of Pt/WO3 was coated on the capillary of the FPI serving as a reaction heater upon hydrogen exposure. The heat locally raised the FPI temperature, which led to the length of air-cavity decrease due to the volume expansion of polymer. Thus, the dip wavelength of interference spectrum yielded a blue shift. The temperature compensation method based on an optical switch was proposed to eliminate the effect of ambient temperature fluctuation. Experimental investigations demonstrated a high sensitivity of -5.1 nm/% at a low hydrogen concentration ranging from 0% to 0.5%.

Zhang, Guilin; Yang, Minghong; Wang, Yao

2014-10-01

157

Planar silicon accelerometer with fiber optic sensing: a system-level study  

Science.gov (United States)

This paper describes the configuration and system design of a single axis silicon micromachined fiber optic accelerometer for inertial navigation systems in spacecraft. The interferometric detection scheme employed to measure the acceleration and the design parameters to be optimized for achieving the required performance of the accelerometer are discussed. The open loop sensitivity of the accelerometer is in the order of milli-g with a dynamic range of +/- 1.2 g.

John, J.; Saha, I.; Islam, R.; Joseph, J.; Lakshmipathy, V. V.; Kanakaraju, K.; Jain, Yashwant K.; Alex, T. K.

2003-10-01

158

Fiber optical distributed temperature and strain sensing system based on Brillouin light scattering  

Science.gov (United States)

In this paper, a two locking lasers BOTDR (Brillouin optical time domain reflectometry) system is demonstrated. Two narrow linewidth DFB lasers are used as the light sources. Their frequencies are locked with a frequency difference of about 11 GHz, which can greatly improve the measurement accuracy and system stability. At a 5-km standard single-mode fiber, distributed temperature measurements can be achieved in lab with a spatial resolution of 10m and a temperature resolution of 2°C.

Li, Yi; Xue, Xianliang; Dong, Xinyong; Zhang, Zaixuan; Jin, Shangzhong

2011-11-01

159

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

160

Small-diameter optical fiber and high-speed wavelength interrogator for FBG/PZT hybrid sensing system  

Science.gov (United States)

We have been developing a sensing system for checking the health of aircraft structures made of composite materials. In this system, lead zirconium titanate (PZT) actuators generate elastic waves that travel through the composite material and are received by embedded fiber Bragg grating (FBG) sensors. By analyzing the change in received waveforms, we can detect various kinds of damage. The frequency of the elastic waves is several hundred kHz, which is too high for a conventional optical spectrum analyzer to detect the wavelength change. Moreover, a conventional single-mode optical fiber cannot be used for an embedded FBG sensor because it is so thick that it induces defects in the composite material structure when it is embedded. We are thus developing a wavelength interrogator with an arrayed waveguide grating (AWG) that can detect the high-speed wavelength change and a small-diameter optical fiber (cladding diameter of 40µm) that does not induce defects. We use an AWG to convert the wavelength change into an output power change by using the wavelength dependency of the AWG transmittance. For this conversion, we previously used two adjacent output ports that cover the reflection spectrum of an FBG sensor. However, this requires controlling the temperature of the AWG because the ratio of the optical power change to the wavelength change is very sensitive to the relationship of the center wavelengths between an FBG sensor and the output ports of the AWG. We have now investigated the use of a denser AWG and six adjacent output ports, which covers the reflection spectrum of an FBG sensor, for detecting the elastic waves. Experimental results showed that this method can suppress the sensitivity of the power change ratio to the relationship of the center wavelengths between an FBG sensor and the output ports. Although our improved small-diameter optical fiber does not induce structural defects in the composite material when it is embedded, there is some micro or macro bending of the fiber, which causes propagation loss. To suppress this embedment loss, we adjusted the refractive index difference of the fiber to have larger value. Experimental result showed that this reduced the embedment loss by about 0.3 dB/cm. These enhancements make our sensing system more practical and should promote the use of composite materials in a wider range of applications.

Komatsuzaki, Shinji; Kojima, Seiji; Hongo, Akihito; Takeda, Nobuo; Sakurai, Takeo

2007-04-01

 
 
 
 
161

Investigation of dual-channel fiber-optic surface plasmon resonance sensing for biological applications.  

Science.gov (United States)

A dual-channel fiber-optic sensor based on surface plasmon resonance (SPR) for self-referencing refractive-index measurements has been proposed. Most applications of fiber-optic SPR sensors are designed to measure the refractive index of a liquid or gas sample by measuring the signal from a single surface, the sensitivity and stability of which is easily affected by the fluctuation of external environmental conditions. We have designed a dual-channel fiber-optic surface sensor with two independent SPR signals from two areas of the same probe. A prototype sensor was fabricated and characterized. The preliminary experimental results demonstrate the characteristic responses of both SPR signals from two channels that independently correspond to the refractive index changes in the liquid samples with which they are in contact. The design could be extended to a multichannel sensor with further developments. The experimental results confirmed that one channel can be used as a reference sensor that could compensate for unexpected changes in bulk refraction or temperature and develop this sensor as a practicable high-sensitivity biosensing device. PMID:16315697

Peng, Wei; Banerji, Soame; Kim, Yoon-Chang; Booksh, Karl S

2005-11-15

162

Fiber-optic Fourier transform infrared spectroscopy for remote label-free sensing of medical device surface contamination  

Science.gov (United States)

As a potential major source of biochemical contamination, medical device surfaces are of critical safety concerns in the clinical practice and public health. The development of innovative sensing methods for accurate and real-time detection of medical device surface contamination is essential to protect patients from high risk infection. In this paper, we demonstrate an alternative fiber-optic Fourier Transform Infrared (FTIR) spectroscopy based sensing approach for remote, non-contact, and label-free detection of biochemical contaminants in the mid-infrared (mid-IR) region. The sensing probe is designed using mid-IR hollow fibers and FTIR measurements are carried out in reflection mode. Bovine Serum Albumin (BSA) and bacterial endotoxin of different concentrations under thoroughly dry condition are used to evaluate the detection sensitivity. The devised system can identify ?0.0025% (?4 × 1011 molecules) BSA and 0.5% (0.5 EU/ml) endotoxin concentration. The developed sensing approach may be applied to detect various pathogens that pose public health threats.

Hassan, Moinuddin; Tan, Xin; Welle, Elissa; Ilev, Ilko

2013-05-01

163

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

164

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

Science.gov (United States)

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 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.

Battista, L.; Sciuto, S. A.; Scorza, A.

2013-03-01

165

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

Energy Technology Data Exchange (ETDEWEB)

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 arrangements has been performed: a measurement range up to 3.00 Multiplication-Sign 10{sup -4} m{sup 3}/s (18.0 l/min) for the mono-directional sensor and a measurement range of {+-}3.00 Multiplication-Sign 10{sup -4} m{sup 3}/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 r{sup 2} is equal to 0.997; for the bi-directional configuration, the coefficient of determination r{sup 2} is equal to 0.990 for positive flows (inspiration) and 0.988 for negative flows (expiration). Measurement uncertainty {delta}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.

Battista, L.; Sciuto, S. A.; Scorza, A. [Department of Engineering, ROMA TRE University, via della Vasca Navale 79/81, Rome (Italy)

2013-03-15

166

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 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.

167

System and method for determination of the reflection wavelength of multiple low-reflectivity bragg gratings in a sensing optical fiber  

Science.gov (United States)

A system and method for determining a reflection wavelength of multiple Bragg gratings in a sensing optical fiber comprise: (1) a source laser; (2) an optical detector configured to detect a reflected signal from the sensing optical fiber; (3) a plurality of frequency generators configured to generate a signal having a frequency corresponding to an interferometer frequency of a different one of the plurality of Bragg gratings; (4) a plurality of demodulation elements, each demodulation element configured to combine the signal produced by a different one of the plurality of frequency generators with the detected signal from the sensing optical fiber; (5) a plurality of peak detectors, each peak detector configured to detect a peak of the combined signal from a different one of the demodulation elements; and (6) a laser wavenumber detection element configured to determine a wavenumber of the laser when any of the peak detectors detects a peak.

Moore, Jason P. (Inventor)

2009-01-01

168

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

169

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

170

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

171

Assessment of GeB doped SiO2 optical fiber for the application of remote radiation sensing system  

Science.gov (United States)

The research and development efforts on the silica (SiO2) optical fiber for application in radiation sensing and other dosimetry field have become quite active. The widely used LiF based dosimeter (TLD) has shown a relatively low reproducibility and there is a time delay in dose assessment which loses its capability as direct real-time dose assessment dosimeters unlike diodes. The macroscopic size of the optical fiber generally does not allow direct in vivo dose sensing in the inner organ for radiotherapy and medical imaging. A flat optical fiber (FF) with nominal dimensions of (0.08 x10 x 10) mm3 of pure silica SiO2 and GeO2 with Boron doped silica fiber SiO2 was selected for this research. The Germanium was used a dopant to enhance the flat optical fiber to reach much higher responsiveness and dose sensitivity in high energy and high dose irradiation. Together with this combination, both TLD dimension and dose assessment issues was hoped to be overcome. The research conducted by comparing the response of pure silica SiO2 flat optical fiber with a GeO2 with Boron doped silica SiO2 flat optical fiber. The FF sample was annealed at 400°C for one hour before irradiated. Kinetic parameters and dosimetric glow curve of TL response and sensitivity were studied with respect to the electron beam of high dose of micro beam irradiation of 1.0 kGy, 5.0 kGy, 10.0 kGy, 50.0 kGy, 100.0 kGy, 500.0 kGy, and 1.0 MGy using Singapore Synchrotron Light Source's (PCIT) beamline. The PCIT operates at 500mA current with real time current range from 90-100mA, dose rate of 3.03 MGy/hour and energy at 8.9KeV. The source to Source Surface Distance (SSD) was at 6.0 cm, with a field size of 20mm × 8mm diameter of a half circle. The TL response was measured using a TLD reader Harshaw Model 3500. The Time-Temperature-Profile (TTP) of the reader was obtained to a preheat temperature of 150 °C for 5 s, the output signal being acquired at a temperature ramprate of 35 °Cs-1, acquisition time of 10 s and a maximum temperature of 400 °C each of the FF samples. All reading was taken under N2 gas flow, suppressing oxidation and potential triboluminescence. The proposed FF shows the excellent TL response for high energy irradiation and good reproducibility and exhibits a very low rate of fading and low variation background signal. From these results, the proposed FF can be used as a radiation dosimeter in remote radiation sensing and favorably compares with the widely used of LiF based dosimeter on common medical radiotherapy application.

Alawiah, A.; Fadhli, M. M.; Bauk, S.; Abdul-Rashid, H. A.; Maah, M. J.

2013-12-01

172

Interferometric Fiber Optic Sensors  

Directory of Open Access Journals (Sweden)

Full Text Available Fiber optic interferometers to sense various physical parameters including temperature, strain, pressure, and refractive index have been widely investigated. They can be categorized into four types: Fabry-Perot, Mach-Zehnder, Michelson, and Sagnac. In this paper, each type of interferometric sensor is reviewed in terms of operating principles, fabrication methods, and application fields. Some specific examples of recently reported interferometeric sensor technologies are presented in detail to show their large potential in practical applications. Some of the simple to fabricate but exceedingly effective Fabry-Perot interferometers, implemented in both extrinsic and intrinsic structures, are discussed. Also, a wide variety of Mach-Zehnder and Michelson interferometric sensors based on photonic crystal fibers are introduced along with their remarkable sensing performances. Finally, the simultaneous multi-parameter sensing capability of a pair of long period fiber grating (LPG is presented in two types of structures; one is the Mach-Zehnder interferometer formed in a double cladding fiber and the other is the highly sensitive Sagnac interferometer cascaded with an LPG pair.

Hae Young Choi

2012-02-01

173

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

174

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

175

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

176

Soil Temperature Variability in Complex Terrain measured using Distributed a Fiber-Optic Distributed Temperature Sensing  

Science.gov (United States)

Soil temperature (Ts) exerts critical environmental controls on hydrologic and biogeochemical processes. Rates of carbon cycling, mineral weathering, infiltration and snow melt are all influenced by Ts. Although broadly reflective of the climate, Ts is sensitive to local variations in cover (vegetative, litter, snow), topography (slope, aspect, position), and soil properties (texture, water content), resulting in a spatially and temporally complex distribution of Ts across the landscape. Understanding and quantifying the processes controlled by Ts requires an understanding of that distribution. Relatively few spatially distributed field Ts data exist, partly because traditional Ts data are point measurements. A relatively new technology, fiber optic distributed temperature system (FO-DTS), has the potential to provide such data but has not been rigorously evaluated in the context of remote, long term field research. We installed FO-DTS in a small experimental watershed in the Reynolds Creek Experimental Watershed (RCEW) in the Owyhee Mountains of SW Idaho. The watershed is characterized by complex terrain and a seasonal snow cover. Our objectives are to: (i) evaluate the applicability of fiber optic DTS to remote field environments and (ii) to describe the spatial and temporal variability of soil temperature in complex terrain influenced by a variable snow cover. We installed fiber optic cable at a depth of 10 cm in contrasting snow accumulation and topographic environments and monitored temperature along 750 m with DTS. We found that the DTS can provide accurate Ts data (+/- .4°C) that resolves Ts changes of about 0.03°C at a spatial scale of 1 m with occasional calibration under conditions with an ambient temperature range of 50°C. We note that there are site-specific limitations related cable installation and destruction by local fauna. The FO-DTS provide unique insight into the spatial and temporal variability of Ts in a landscape. We found strong seasonal trends in Ts variability controlled by snow cover and solar radiation as modified by topography. During periods of spatially continuous snow cover Ts was practically homogeneous throughout. In the absence of snow cover, Ts is highly variable, with most of the variability attributable to different topographic units defined by slope and aspect. During transition periods when snow melts out, Ts is highly variable within the watershed and within topographic units. The importance of accounting for these relatively small scale effects is underscored by the fact that the overall range of Ts in study area 600 m long is similar to that of the much large RCEW with 900 m elevation gradient.

Seyfried, M. S.; Link, T. E.

2013-12-01

177

Fiber optic chemical sensors on Mars  

Energy Technology Data Exchange (ETDEWEB)

A fiber optic chemical sensing instrument is described that will measure the reactivity of the martian soil and atmosphere. The self- contained instrument monitors reflectivity changes in reactive thin films caused by chemical reactions with the martian soil or atmosphere. Data from over 200 separate thin-film-coated optical fibers are recorded simultaneously. This fiber optic sensing technology has many advantages for planetary exploration and monitoring applications on manned spacecraft, in addition to many practical terrestrial uses.

Butler, M.A.; Ricco, A.J. [Sandia National Labs., Albuquerque, NM (United States); Grunthaner, F.J.; Lane, A.L. [Jet Propulsion Lab., Pasadena, CA (United States)

1993-12-31

178

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

179

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.

180

A Sensing Element Based on a Bent and Elongated Grooved Polymer Optical Fiber  

Science.gov (United States)

An experimental and numerical investigation is performed into the power loss induced in grooved polymer optical fibers (POFs) subjected to combined bending and elongation deformations. The power loss is examined as a function of both the groove depth and the bend radius. An elastic-plastic three-dimensional finite element model is constructed to simulate the deformation in the grooved region of the deformed specimens. The results indicate that the power loss increases significantly with an increasing bending displacement or groove depth. Specifically, the power loss increases to as much as 12% given a groove depth of 1.1 mm and a bending displacement of 10 mm. Based on the experimental results, an empirical expression is formulated to relate the power loss with the bending displacement for a given groove depth. It is shown that the difference between the estimated power loss and the actual power loss is less than 2%. PMID:22969356

Lu, Wei-Hua; Chen, Li-Wen; Xie, Wen-Fu; Chen, Yung-Chuan

2012-01-01

 
 
 
 
181

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

182

Fiber Optics Technology.  

Science.gov (United States)

Discusses various applications of fiber optics technology: information systems, industrial robots, medicine, television, transportation, and training. Types of jobs that will be available with fiber optics training (such as electricians and telephone cable installers and splicers) are examined. (CT)

Burns, William E.

1986-01-01

183

Fiber optic radiation sensors  

Science.gov (United States)

A survey of fiber-optic sensors for the measurement of ionizing radiation is given. The interactions between ionizing radiation and fiber material, which are of significance for the fiber-optic detection of ionizing radiation, as well as the changes in the properties of the optical fibers induced by such interactions are discussed. Measurement and evaluation techniques for reading out the optical properties induced by ionizing radiation are described. A survey of possible applications for fiber-optic radiation sensors is given. The properties and application possibilities of fiber-optic dosimeters based on radiation-induced losses are specified. In particular, the requirements to be met by fiber-optic dosimeters for applications in radiation therapy are discussed. A fiber-optic dosimeter measuring system for radiation therapy based on radiation-induced losses is presented.

Bueker, Harald; Haesing, Friedrich W.

1994-12-01

184

The Fiber Optic Connection.  

Science.gov (United States)

Describes the fiber optics programs at the Career and Technical Center in Berlin, Pennsylvania and the Charles S. Monroe Technology Center in Loudoun County, Virginia. Discusses the involvement of the Fiber Optic Association with education, research and development, manufacturing, sales, distribution, installation, and maintenance of fiber optic

Reese, Susan

2003-01-01

185

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

186

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

187

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

188

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

189

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

190

Comparison of Al2O3 nano-overlays deposited with magnetron sputtering and atomic layer deposition on optical fibers for sensing purposes  

Science.gov (United States)

In this work we compare effects of thin (LPG) in the fiber prior the deposition. Thanks to LPG sensitivity to thickness and optical properties of the overlays deposited on the fiber, we are able to monitor Al2O3 nano-overlay properties. Moreover, we investigate an influence of the overlays deposited with both the methods on LPG-based refractive index (RI) sensing. We show and discuss tuning of the RI sensitivity by proper selection of both thickness and optical properties of the Al2O3 nano-overlays.

?mietana, Mateusz; DrÄ ?ewski, Tomasz; Firek, Piotr; Mikulic, Predrag; Bock, Wojtek J.

2013-12-01

191

Rayleigh fiber optics gyroscope  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

192

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

193

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

194

Polarization in optical fibers  

CERN Document Server

This essential book analyzes polarization effects, including non-linear effects, and their influence in communications and sensing. You get full details on telecom system degradation caused by PMD, PDL, and PDG and techniques for mitigating it, plus insight into the effects and consequences of polarization on solitons, amplifiers, and switches. Fiber polarization in sensing applications is explained through detailed treatment of such key issues as stress/strain, displacement, point sensing, and distributed sensing.

Rogers, Alan

2008-01-01

195

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

196

Single mode tapered fiber-optic interferometer based refractive index sensor and its application to protein sensing.  

Science.gov (United States)

We demonstrate refractive index sensors based on single mode tapered fiber and its application as a biosensor. We utilize this tapered fiber optic biosensor, operating at 1550 nm, for the detection of protein (gelatin) concentration in water. The sensor is based on the spectroscopy of mode coupling based on core modes-fiber cladding modes excited by the fundamental core mode of an optical fiber when it transitions into tapered regions from untapered regions. The changes are determined from the wavelength shift of the transmission spectrum. The proposed fiber sensor has sensitivity of refractive index around 1500 nm/RIU and for protein concentration detection, its highest sensitivity is 2.42141 nm/%W/V. PMID:25321749

Yadav, T K; Narayanaswamy, R; Abu Bakar, M H; Kamil, Y Mustapha; Mahdi, M A

2014-09-22

197

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

198

A real-time structural parametric identification system based on fiber optic sensing and neural network algorithms  

Science.gov (United States)

A structural parametric identification strategy based on neural networks algorithms using dynamic macro-strain measurements in time domain from a long-gage strain sensor by fiber optic sensing technique such as Fiber Bragg Grating (FBG) sensor is developed. An array of long-gage sensors is bounded on the structure to measure reliably and accurately macro-strains. By the proposed methodology, the structural parameter of stiffness can be identified. A beam model with known mass distribution is considered as an object structure. Without any eigenvalue analysis or optimization computation, the structural parameter of stiffness can be identified. First an emulator neural network is presented to identify the beam structure in current state. Free vibration macro-strain responses of the beam structure are used to train the emulator neural network. The trained emulator neural network can be used to forecast the free vibration macro-strain response of the beam structure with enough precision and decide the difference between the free vibration macro-strain responses of other assumed structure with different structural parameters and those of the original beam structure. The root mean square (RMS) error vector is presented to evaluate the difference. Subsequently, corresponding to each assumed structure with different structural parameters, the RMS error vector can be calculated. By using the training data set composed of the structural parameters and RMS error vector, a parametric evaluation neural network is trained. A beam structure is considered as an existing structure, based on the trained parametric evaluation neural network, the stiffness of the beam structure can be forecast. It is shown that the parametric identification strategy using macro-strain measurement from long-gage sensors has the potential of being a practical tool for a health monitoring methodology applied to civil engineering structures.

Wu, Zhishen; Xu, Bin

2003-07-01

199

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

Science.gov (United States)

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

200

Fiber Optics Basics  

Science.gov (United States)

This pdf from OP-TEC, the National Center for Optics and Photonics Education, addresses basic concepts underlying the operation of fiber lasers. This free 26 page document supplements the fiber laser material presented in an Elements of Photonics Course by provided a more current and detailed description of how lasers operate. This course covers basic laser operations, basic structure of fiber lasers, pulsing methods, output characteristics of fiber lasers, and advanced structures.

2012-12-04

 
 
 
 
201

Fiber optic detector for immuno-testing  

Science.gov (United States)

A portable fiber optic detector that senses the presence of specific target chemicals in air or a gas by exchanging the target chemical for a fluoroescently-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, Judy K. (Idaho Falls, ID); Ward, Thomas E. (Idaho Falls, ID); Grey, Alan E. (Idaho Falls, ID)

1992-01-01

202

Fiber optic spanner  

Science.gov (United States)

Rotation is a fundamental function in nano/biotechnology and is being useful in a host of applications such as pumping of fluid flow in microfluidic channels for transport of micro/nano samples. Further, controlled rotation of single cell or microscopic object is useful for tomographic imaging. Though conventional microscope objective based laser spanners (based on transfer of spin or orbital angular momentum) have been used in the past, they are limited by the short working distance of the microscope objective. Here, we demonstrate development of a fiber optic spanner for rotation of microscopic objects using single-mode fiber optics. Fiber-optic trapping and simultaneous rotation of pin-wheel structure around axis perpendicular to fiber-optic axis was achieved using the fiber optic spanner. By adjusting the laser beam power, rotation speed of the trapped object and thus the microfluidic flow could be controlled. Since this method does not require special optical or structural properties of the sample to be rotated, three-dimensional rotation of a spherical cell could also be controlled. Further, using the fiber optic spanner, array of red blood cells could be assembled and actuated to generate vortex motion. Fiber optical trapping and spinning will enable physical and spectroscopic analysis of microscopic objects in solution and also find potential applications in lab- on-a-chip devices.

Black, Bryan; Mohanty, Samarendra

2011-10-01

203

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

204

Optical fiber Sagnac interferometer for sensing scalar directional refraction: application to magnetochiral birefringence  

CERN Document Server

We present a set-up dedicated to the measurement of the small scalar directional anisotropies associated to the magnetochiral interaction. The apparatus, based on a polarization-independent fiber Sagnac interferometer, is optimized to be insensitive to circular anisotropies and to residual absorption. It can thus characterize samples of biological interests, for which the two enantiomers are not available and/or which present poor transmission. The signal-to-noise ratio is shown to be limited only by the source intensity noise, leading to a detection limit of Df = 500 nrad.Hz-1/2. It yields a limit on the magnetochiral index nMC < 4 10-13 T-1 at 1550 nm for the organic molecules tested.

Loas, Goulc'hen; Vallet, Marc

2014-01-01

205

Shape Sensing a Morphed Wing with an Optical Fiber Bragg Grating  

Science.gov (United States)

We suggest using distributed fiber Bragg sensors systems which were developed locally at Langley Research Center carefully placed on the wing surface to collect strain component information at each location. Then we used the fact that the rate change of slope in the definition of linear strain is very small and can be treated as a constant. Thereby the strain distribution information of a morphed surface can be reduced into a distribution of local slope information of a flat surface. In other words a morphed curve surface is replaced by the collection of individual flat surface of different slope. By assembling the height of individual flat surface, the morphed curved surface can be approximated. A more sophisticated graphic routine can be utilized to restore the curved morphed surface. With this information, the morphed wing can be further adjusted and controlled. A numerical demonstration is presented.

Tai, Hsiang

2005-01-01

206

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

207

Liquid Crystal Devices for Optical Communications and Sensing Applications  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This thesis is focussed on the design and development of liquid crystal based tunable photonic devices for applications in optical communications and optical sensing, with an emphasis on all-fiber device configuration. The infiltration of liquid crystals into photonic crystal fiber provides a suitable common platform to design and fabricate simple and compact all-fiber tunable photonic devices which can be easily integrated with optical fiber networks and sensing systems. Based on the infiltr...

Mathews, Sunish

2011-01-01

208

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, LEDâÂÂs, 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.

2009-04-28

209

Fiber optic communication links  

Energy Technology Data Exchange (ETDEWEB)

Fiber optics is a new, emerging technology which offers relief from many of the problems which limited past communications links. Its inherent noise immunity and high bandwidth open the door for new designs with greater capabilities. Being a new technology, certain problems can be encountered in specifying and installing a fiber optic link. A general fiber optic system is discussed with emphasis on the advantages and disadvantages. It is not intended to be technical in nature, but a general discussion. Finally, a general purpose prototype Sandia communications link is presented.

Meyer, R. H.

1980-01-01

210

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

211

Fiber Optic Neural Network  

Science.gov (United States)

Optical neural networks offer favorable features compared to their counterpart digital implementations for pattern recognition purposes, such as signal throughput; they also provide technological challenges, such as optical to electronic interfaces, as well as practical considerations, such as cost. A fiber optic neural network is proposed here which can be implemented with readily available optical components; namely, laser diodes, laser amplifiers, erbium doped fiber amplifiers, and photodiodes. The neural network modelled here is configured arbitrarily with four inputs, four outputs, and one hidden layer. Supervised training has been accomplished via the feedforward error backpropagation scheme. The artificial neural network program JETNET 2.0 has been adapted at the computational facilities of the Center for Applied Optics at UTD in order to simulate the performance of the fiber optic neural network under investigation. Results obtained show that the proposed construction is capable of attaining full convergence with various training sets, thereby exhibiting flexibility and learning capacity to perform as a pattern recognition instrument.

Fernandes, Juvenal Gregorio

212

Vapor sensing properties of carbon nanotubes onto cadmium arachidate multilayer investigated by optical-fiber-based reflectometer sensor and acoustic sensors  

Science.gov (United States)

We have investigated the sensing properties of the carbon nanotubes deposited onto a cadmium arachidate buffered multilayer by acoustic sensors -- SAW and QCM -- and a reflectometric sensor system based on optical fiber for purposes of chemical detection of volatile organic compound (VOCs), at room temperature. The carbon nanotubes have been deposited by the molecular engineering Langmuir-Blodgett (L-B) technique onto a buffer multilayer of cadmium arachidate prepared monolayer-by-monolayer using the L-B technique as well. The sensing multilayered material has been prepared both onto a standard silica optical fiber configured in a reflectometer sensor system and onto acoustic sensors -- SAW and QCM -- configured as oscillators. The acoustic sensors and the optical sensor have been exposed simultaneously, in the same test chamber, towards different VOCs such as ethanol, methanol, iso-propanol, acetone, ethylacetate, toluene with different vapor pressures for comparing the sensitivity of the coating onto the different kinds of acoustic and optical transducers. Moreover, for the same type of transducer, acoustic or optical, the effect of carbon nanotubes onto the gas sensitivity is remarkably higher in all investigated cases.

Cusano, A.; Cutolo, Antonello; Penza, M.; Cassano, G.; Aversa, P.; Antolini, F.; Giordano, Michele

2004-06-01

213

Recent Development in Optical Fiber Biosensors  

Directory of Open Access Journals (Sweden)

Full Text Available Remarkable developments can be seen in the field of optical fibre biosensors in the last decade. More sensors for specific analytes have been reported, novel sensing chemistries or transduction principles have been introduced, and applications in various analytical fields have been realised. This review consists of papers mainly reported in the last decade and presents about applications of optical fiber biosensors. Discussions on the trends in optical fiber biosensor applications in real samples are enumerated.

Catalina Bosch Ojeda

2007-06-01

214

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

215

Mustiscaling Analysis applied to field Water Content through Distributed Fiber Optic Temperature sensing measurements  

Science.gov (United States)

Soils can be seen as the result of spatial variation operating over several scales. This observation points to 'variability' as a key soil attribute that should be studied. Soil variability has often been considered to be composed of 'functional' (explained) variations plus random fluctuations or noise. However, the distinction between these two components is scale dependent because increasing the scale of observation almost always reveals structure in the noise. Geostatistical methods and, more recently, multifractal/wavelet techniques have been used to characterize scaling and heterogeneity of soil properties among others coming from complexity science. Multifractal formalism, first proposed by Mandelbrot (1982), is suitable for variables with self-similar distribution on a spatial domain (Kravchenko et al., 2002). Multifractal analysis can provide insight into spatial variability of crop or soil parameters (Vereecken et al., 2007). This technique has been used to characterize the scaling property of a variable measured along a transect as a mass distribution of a statistical measure on a spatial domain of the studied field (Zeleke and Si, 2004). To do this, it divides the transect into a number of self-similar segments. It identifies the differences among the subsets by using a wide range of statistical moments. Wavelets were developed in the 1980s for signal processing, and later introduced to soil science by Lark and Webster (1999). The wavelet transform decomposes a series; whether this be a time series (Whitcher, 1998; Percival and Walden, 2000), or as in our case a series of measurements made along a transect; into components (wavelet coefficients) which describe local variation in the series at different scale (or frequency) intervals, giving up only some resolution in space (Lark et al., 2003, 2004). Wavelet coefficients can be used to estimate scale specific components of variation and correlation. This allows us to see which scales contribute most to signal variation, or to see at which scales signals are most correlated. This can give us an insight into the dominant processes An alternative to both of the above methods has been described recently. Relative entropy and increments in relative entropy has been applied in soil images (Bird et al., 2006) and in soil transect data (Tarquis et al., 2008) to study scale effects localized in scale and provide the information that is complementary to the information about scale dependencies found across a range of scales. We will use them in this work to describe the spatial scaling properties of a set of field water content data measured in an extension of a corn field, in a plot of 500 m2 and an spatial resolution of 25 cm. These measurements are based on an optics cable (BruggSteal) buried on a ziz-zag deployment at 30cm depth. References Bird, N., M.C. Díaz, A. Saa, and A.M. Tarquis. 2006. A review of fractal and multifractal analysis of soil pore-scale images. J. Hydrol. 322:211-219. Kravchenko, A.N., R. Omonode, G.A. Bollero, and D.G. Bullock. 2002. Quantitative mapping of soil drainage classes using topographical data and soil electrical conductivity. Soil Sci. Soc. Am. J. 66:235-243. Lark, R.M., A.E. Milne, T.M. Addiscott, K.W.T. Goulding, C.P. Webster, and S. O'Flaherty. 2004. Scale- and location-dependent correlation of nitrous oxide emissions with soil properties: An analysis using wavelets. Eur. J. Soil Sci. 55:611-627. Lark, R.M., S.R. Kaffka, and D.L. Corwin. 2003. Multiresolution analysis of data on electrical conductivity of soil using wavelets. J. Hydrol. 272:276-290. Lark, R. M. and Webster, R. 1999. Analysis and elucidation of soil variation using wavelets. European J. of Soil Science, 50(2): 185-206. Mandelbrot, B.B. 1982. The fractal geometry of nature. W.H. Freeman, New York. Percival, D.B., and A.T. Walden. 2000. Wavelet methods for time series analysis. Cambridge Univ. Press, Cambridge, UK. Tarquis, A.M., N.R. Bird, A.P. Whitmore, M.C. Cartagena, and Y. Pachepsky. 2008. Multiscale analysis of soil transect data. Vadose Zone J. 7: 563-569. Vere

Benitez Buelga, Javier; Rodriguez-Sinobas, Leonor; Sanchez, Raul; Gil, Maria; Tarquis, Ana M.

2014-05-01

216

Fiber optic pressure sensors for nuclear power plants  

International Nuclear Information System (INIS)

gulatory Commission (NRC) to assess the performance and reliability of existing fiber optic pressure sensors for use in nuclear power plants. This assessment will include establishment of the state of the art in fiber optic pressure sensing, characterization of the reliability of fiber optic pressure sensors, and determination of the strengths and limitations of these sensors for nuclear safety-related services

217

Miniature fiber optic surface plasmon resonance biosensors  

Science.gov (United States)

A novel design of surface plasmon resonance fiber optic sensor is reported which leads to a compact, highly miniaturized sensing element with excellent sensitivity. The sensing device is based on a side-polished single-mode optical fiber with a thin metal overlayer supporting surface plasmon waves. The strength of interaction between a fiber mode and a surface plasmon wave depends strongly on the refractive index near the sensing surface. Therefore, refractive index changes associated with biospecific interaction between antibodies immobilized on the sensor and antigen molecules can be monitored by measuring light intensity variations. Detection of horse radish peroxidase (HRP) of the concentration of 100 ng/ml has been accomplished using the fiber optic sensor with a matrix of monoclonal antibodies against HRP immobilized on the sensor surface.

Slavik, Radan; Brynda, Eduard; Homola, Jiri; Ctyroky, Jiri

1999-01-01

218

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

219

Fiber optic interferometric accelerometers  

Energy Technology Data Exchange (ETDEWEB)

Recent progress on the development of flexural disk based fiber optic acceleration sensors is reported. Appropriate geometric considerations have resulted in fiber optic accelerometers with many desirable features including (i) high sensitivity ({approx_gt}20 dB rerad/g), (ii) flat frequency response (200 Hz to {approx_gt}10 kHz), and (iii) low pressure ({lt}{minus}180 dB rerad/{mu}Pa) and transverse sensitivity ({lt}{minus}30 dB). Alternate transducer designs are discussed and preliminary results reported. Various optical multiplexing schemes for accelerometer arrays are discussed. {copyright} {ital 1996 American Institute of Physics.}

Vohra, S.T.; Danver, B.; Tveten, A.; Dandridge, A. [Naval Research Laboratory, Optical Science Division, Code 5670, Washington, District of Columbia 20375 (United States)

1996-04-01

220

Investigation of gold-coated bare fiber probe for in situ intra-vitreous coherence domain optical imaging and sensing  

Science.gov (United States)

We have investigated the usage of gold-plated bare fiber probes for in situ imaging of retinal layers and surrounding ocular tissues using time-domain common-path optical coherence tomography. The fabricated intra-vitreous gold-plated micro-fiber probe can be fully integrated with surgical tools working in close proximity to the tissue to provide subsurface images having a self-contained reference plane independent to the Fresnel reflection between the distal end of the probe and the following medium for achieving reference in typical common-path optical coherence tomography. We have fully characterized the probe in an aqueous medium equivalent to the vitreous humor in the eye and were able to differentiate various functional retinal tissue layers whose thickness is larger than the system’s resolution.

Han, J.-H.; Ilev, I. K.; Kim, D.-H.; Song, C. G.; Kang, J. U.

2010-06-01

 
 
 
 
221

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

222

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

223

Multimode fiber optics  

Science.gov (United States)

In 2012, Loyola University Maryland and Rockhurst University received a grant to develop three upper-­?division active learning physics modules that relate physics principles to medicine. One of these modules is concerned with multimode fiber optics. The teaching materials for fiber optics are divided into two levels: Level 1 is appropriate for introductory/intermediate students and Level 2 is designed for intermediate/advanced students. Level 2 materials concentrate on the physics and experimental techniques of coupling laser light into a 200 um fiber, and are suitable for students who may encounter optics in research or industrial environments. In the process of working with Level 2 materials, the students will learn about numerical aperture, beam waist due to diffraction and spherical aberration, optical alignment techniques, overfilling and underfilling of fibers, skew rays, loss, and applications of fiber optics in medicine and other fields. We wish to acknowledge support from NSF TUES grant 1140406. Presented at the 2013 AAPT Summer Meeting, W36: Advanced Labs Workshop

Lowe, Mary

2013-10-02

224

Optical fiber stripper positioning apparatus  

Science.gov (United States)

An optical fiber positioning apparatus for an optical fiber stripping device is disclosed which is capable of providing precise axial alignment between an optical fiber to be stripped of its outer jacket and the cutting blades of a stripping device. The apparatus includes a first bore having a width approximately equal to the diameter of an unstripped optical fiber and a counter bore axially aligned with the first bore and dimensioned to precisely receive a portion of the stripping device in axial alignment with notched cutting blades within the stripping device to thereby axially align the notched cutting blades of the stripping device with the axis of the optical fiber to permit the notched cutting blades to sever the jacket on the optical fiber without damaging the cladding on the optical fiber. In a preferred embodiment, the apparatus further includes a fiber stop which permits determination of the length of jacket to be removed from the optical fiber.

Fyfe, Richard W. (Las Vegas, NV); Sanchez, Jr., Amadeo (Las Vegas, NV)

1990-01-01

225

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

226

Optical-fiber penetration devices  

International Nuclear Information System (INIS)

Optical communications use optical-fiber signal-transmission lines and optical-fiber penetration instead of conventional wire penetration. Optical-fiber penetration devices must be gastight and have low transmission losses, characteristics which must be guaranteed irrespective of ambient conditions. Mitsubishi Electric has developed two methods of optical-fiber penetration, which are introduced in the article: hermetically sealed and organic material sealed. Both provide excellent resistance to environmental factors, including heat, radiation, and seismic distrubance. (author)

227

Fiber Optic Polarimetric Sensor (FOPS) for dynamic applications  

Science.gov (United States)

Dynamic analysis of structures and machines provide valuable information on the performance and reliability of structures. In this paper, we present the development of a Fiber Optic Polarimetric Sensor (FOPS*) for dynamic and impact loading. The sensor monitors the change in the state of polarization of the light beam traversing the fiber under dynamic loading. The dynamic response of three different sensing optical fibers - high birefringence (bow-tie) fiber, low birefringence fiber and an ordinary communication grade single mode fiber are evaluated. The studies were carried out by embedding the optical fibers in a glass fiber reinforced plastic (GFRP) specimen and the performances of the three different systems were compared.

John, M. Shelly; Murukeshan, Vadakke M.; Asundi, Anand K.

2001-10-01

228

Integration of thin films with fiber micro-structures for sensing applications  

Science.gov (United States)

The combination of fiber optics with micro-structure technologies and sensitive thin films offers great potential for the realization of novel sensor concepts. Minitured optical fiber sensors with thin films as sensitive elements could open new fields for optical fiber sensor applications. Thin films work as sensitive elements and transducer to get response and feedback from environments, optical fiber here are employed to signal carrier. This paper reviews some works on the integration of thin films with fiber micro-structures for sensing application, which are currently conducted at the National Engineering Laboratory for Fiber Optic Sensing Technologies, Wuhan University of Technology.

Yang, Minghong; Wang, Min; Zhang, Guilin

2013-06-01

229

Applications of nonlinear fiber optics  

CERN Document Server

* The only book describing applications of nonlinear fiber optics * Two new chapters on the latest developments: highly nonlinear fibers and quantum applications* Coverage of biomedical applications* Problems provided at the end of each chapterThe development of new highly nonlinear fibers - referred to as microstructured fibers, holey fibers and photonic crystal fibers - is the next generation technology for all-optical signal processing and biomedical applications. This new edition has been thoroughly updated to incorporate these key technology developments.The bo

Agrawal, Govind P

2008-01-01

230

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

231

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.

2013-07-19

232

Enhanced radiation resistant fiber optics  

Science.gov (United States)

A process for producing an optical fiber having enhanced radiation resitance is provided, the process including maintaining an optical fiber within a hydrogen-containing atmosphere for sufficient time to yield a hydrogen-permeated optical fiber having an elevated internal hydrogen concentration, and irradiating the hydrogen-permeated optical fiber at a time while the optical fiber has an elevated internal hydrogen concentration with a source of ionizing radiation. The radiation source is typically a cobalt-60 source and the fiber is pre-irradiated with a dose level up to about 1000 kilorads of radiation.

Lyons, Peter B. (Los Alamos, NM); Looney, Larry D. (Los Alamos, NM)

1993-01-01

233

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

234

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

235

Polymer optical fiber amplifier  

Science.gov (United States)

Polymer optical fiber amplifiers (POFA) of graded-index (GI) type, which have a gain in visible region, were successfully prepared by the interfacial-gel polymerization technique. The gain of 27 dB was observed at 591 nm signal wavelength with 690 W launched pump power at 532 nm in a GI POFA with 0.5 m length.

Tagaya, A.; Koike, Y.; Kinoshita, T.; Nihei, E.; Yamamoto, T.; Sasaki, K.

1993-08-01

236

Tapered fiber tips for fiber optic biosensors  

Science.gov (United States)

Tapered fiber tips with different geometries are fabricated for developing a fiber optic biosensor. Fluorescence experiments are performed to compare the coupling efficiency of light for different fiber tip configurations. When light is generated in a `thick' layer (> 1 micrometers ) around a fiber core, the continuously tapered tip with the steepest taper collects light more efficiently than the longer combination tapered tip. To demonstrate the applicability of our results, we have successfully detected weak chemiluminescent signal collected by a bundle of fibers with the short continuously tapered tips using a cooled CCD array detector. The chemiluminescence reaction was catalyzed by alkaline phosphatase immobilized on the fiber tips by a sol-gel technique.

Gao, Harry H.; Chen, Zhongping; Kumar, Jayant; Tripathy, Sukant K.; Kaplan, David L.

1995-12-01

237

Aerogel-clad optical fiber  

Science.gov (United States)

An optical fiber is surrounded by an aerogel cladding. For a low density aerogel, the index of refraction of the aerogel is close to that of air, which provides a high numerical aperture to the optical fiber. Due to the high numerical aperture, the aerogel clad optical fiber has improved light collection efficiency.

Sprehn, Gregory A. (Livermore, CA); Hrubesh, Lawrence W. (Pleasanton, CA); Poco, John F. (Livermore, CA); Sandler, Pamela H. (San Marino, CA)

1997-01-01

238

Buying Fiber-Optic Networks.  

Science.gov (United States)

Describes consortia formed by college and university administrators to buy, manage, and maintain their own fiber-optic networks with the goals of cutting costs of leasing fiber-optic cable and planning for the future. Growth capacity is the real advantage of owning fiber-optic systems. (SLD)

Fickes, Michael

2003-01-01

239

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)

240

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

 
 
 
 
241

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

242

Nonlinear fiber optics  

CERN Document Server

Since the 4e appeared, a fast evolution of the field has occurred. The 5e of this classic work provides an up-to-date account of the nonlinear phenomena occurring inside optical fibers, the basis of all our telecommunications infastructure as well as being used in the medical field. Reflecting the big developments in research, this new edition includes major new content: slow light effects, which offers a reduction in noise and power consumption and more ordered network traffic-stimulated Brillouin scattering; vectorial treatment of highly nonlinear fibers; and a brand new chapter o

Agrawal, Govind

2012-01-01

243

Introduction to optical fiber sensors  

International Nuclear Information System (INIS)

Optical fiber sensors have many advantages over other types of sensors, for example: Low weight, immunity from EMI, electrical isolation, chemical passivity, and high sensitivity. In this seminar, a brief explanation of the optical fiber sensors, their use, and their advantages will be given. After, a description of the main optical fiber sensor components will be presented. Principles of some kinds of optical fiber sensors will be presented, and the principle of the fiber-optic rotation sensor and its realization will be discussed in some details, as well as its main applications. (author). 5 refs, 8 figs, 2 tabs

244

Fiber optic Bragg grating model  

Science.gov (United States)

Photoinduced bragg grating in optical fibers were first demonstrated in 1978. In 1988, an external bragg grating writing technique which had more flexibility in the choice of the Bragg period was developed. Since then and due to their unique properties a number of sensing concepts have been proposed and demonstrated. Most of these sensors are configured as back reflectors. A more general configuration, a tapped bragg grating (TBG), was first demonstrated in 1991. A complete theory for the fabrication and operation of TBG's is still incomplete. In this report a simple model of tapped bragg gratings is developed. This model will allow the understanding of the basic parameters necessary to fabricate TBG's. Several questions have to be answered to effectively fabricate a TBG sensor. Some of these questions are, what must the Bragg angle and period Theta (sub B) and Delta (sub B) be in order to effectively scatter radiation out of the fiber at a desired scattering angle Theta.

Perez, Ignacio; Bibby, Thomas; Ryan, Marty

1995-06-01

245

In-fiber integrated chemiluminiscence online optical fiber sensor.  

Science.gov (United States)

We report an in-fiber integrated chemiluminiscence (CL) sensor based on a kind of hollow optical fiber with a suspended inner core. The path of microfluid is realized by etching microholes for inlets and outlets on the surface of the optical fiber without damaging the inner core and then constructing a melted point beside the microhole of the outlet. When samples are injected into the fiber, the liquids can be fully mixed and form steady microflows. Simultaneously, the photon emitted from the CL reaction is efficiently coupled into the core and can be detected at the end of the optical fiber. In this Letter, the concentration of H2O2 samples is analyzed through the emission intensity of the CL reaction among H2O2, luminol, K3Fe(CN)6, and NaOH in the optical fiber. The linear sensing range of 0.1-4.0 mmol/L of H2O2 concentration is obtained. The emission intensity can be determined within 400 ms at a total flow rate of 150 ?L/min. Significantly, this work presents the information of developing in-fiber integrated online analyzing devices based on optical methods. PMID:23988977

Yang, Xinghua; Yuan, Tingting; Yang, Jun; Dong, Biao; Liu, Yanxin; Zheng, Yao; Yuan, Libo

2013-09-01

246

Advances on Optical Fiber Sensors  

Directory of Open Access Journals (Sweden)

Full Text Available In this review paper some recent advances on optical fiber sensors are reported. In particular, fiber Bragg grating (FBG, long period gratings (LPGs, evanescent field and hollow core optical fiber sensors are mentioned. Examples of recent optical fiber sensors for the measurement of strain, temperature, displacement, air flow, pressure, liquid-level, magnetic field, and the determination of methadone, hydrocarbons, ethanol, and sucrose are briefly described.

Luciano Mescia

2013-12-01

247

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

248

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

249

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.

2013-06-10

250

Polarimetric optical fiber refractometer.  

Science.gov (United States)

An optical fiber refractometer based on a photometric return-path birefringence sensor is proposed. For measuring the refractive index, the phase shift between polarization components on total internal reflection inside a refractometric prism is used. Several kinds of refractometric prism are described. It is shown that a refractive-index sensitivity of 0.0001 and higher for a wide range of index values is attainable. PMID:18357282

Shribak, M

2001-06-01

251

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

252

Fiber structure based on a depressed inner cladding fiber for bend, refractive index and temperature sensing  

Science.gov (United States)

A fiber-optic structure based on a section of a double-clad fiber with depressed inner cladding is investigated for bend, refractive index and temperature sensing. The structure is formed by splicing a section of SM630 fiber between two standard fibers SMF-28. The operation principle relies on the sensitivity of cladding modes that are induced at a splice of fibers having different refractive index profiles. The mode structure of the double cladding fiber and the mechanism of formation of dips in the transmission spectra are discussed. The transmission spectra of the structure are measured for different curvatures of the inserted fiber section. The shift of dips to long wavelengths with increasing curvature of the fiber is observed and its dependence on the fiber section length and the direction of bending is investigated. The sensitivities of the spectral dips to the external refractive index and temperature are also measured.

Ivanov, Oleg V.; Zlodeev, Ivan V.

2014-01-01

253

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

254

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

255

Fiber-optic seismic sensor  

International Nuclear Information System (INIS)

A vibration sensor is constructed by providing two preferably matched coils of fiber-optic material. When the sensor experiences vibration, a differential pressure is exerted on the two fiber coils. The differential pressure results in a variation in the relative optical path lengths between the two fibers so that light beams transmitted through the two fibers are differently delayed, the phase difference therebetween being a detectable indication of the vibration applied to the sensor

256

Fiber optic micro sensor for the measurement of tendon forces  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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...

Behrmann Gregory P; Hidler Joseph; Mirotznik Mark S

2012-01-01

257

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

258

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.

2011-08-11

259

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

260

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

 
 
 
 
261

Fiber optic geophysical sensors  

Science.gov (United States)

A fiber optic geophysical sensor is described in which laser light is passed through a sensor interferometer in contact with a geophysical event, and a reference interferometer not in contact with the geophysical event but in the same general environment as the sensor interferometer. In one embodiment, a single tunable laser provides the laser light. In another embodiment, separate tunable lasers are used for the sensor and reference interferometers. The invention can find such uses as monitoring for earthquakes, and the weighing of objects. 2 figures.

Homuth, E.F.

1991-03-19

262

A fiber optic Bragg grating seismic sensor  

Science.gov (United States)

Here we present a fiber optic seismic waves sensor based on in-fiber Bragg gratings. Fiber Bragg Grating sensors have been demonstrated to have very high sensitivity to dynamical strain in the sub-micro-strain range and very extended dynamical response from static to very high frequency. The seismic sensing system is based on the integration of three FBGs dynamical strain sensors in a mechanical structure acting as an inverse pendulum. Polar symmetry of the mechanical system and 120° placement of the FBG sensors guarantee a directional capability of the seismic sensor. Design, manufacturing and preliminary dynamical testing of the seismic sensor are discussed.

Laudati, A.; Mennella, F.; Esposito, M.; Cusano, A.; Giordano, M.; Breglio, G.; Sorge, S.; Calisti Tassini, C.; Torre, A.; D'Altrui, G.; Cutolo, A.

2007-07-01

263

Graphene-based all-fiber-optic temperature sensor  

Science.gov (United States)

A novel all fiber-optic temperature sensor based on graphene film coated on a side polished fiber (SPF) was demonstrated. Significantly enhanced interaction between the propagating light and the graphene film can be achieved via strong evanescent light of the SPF. The experiments shows that the strong interaction results in temperature sensing with a dynamic optical power variation of 11.3dB in SPF. The novel temperature fiber sensor possesses a linear correlation coefficient of 99.4%, a sensitivity of 0.13dB/°C, a precision of better than 0.03°C. Furthermore, the graphene-based all fiber-optic temperature sensor is easy to fabricate, compatible with fiber-optic systems and possesses high potentiality in photonics applications such as all fiber-optic temperature sensing network.

Lu, Huihui; Tian, Zhengwen; Jin, Shaoshen; Yu, Jianhui; Liao, Guozhen; Zhang, Jun; Tang, Jieyuan; Luo, Yunhan; Chen, Zhe

2014-03-01

264

Optical-Fiber Leak Detector  

Science.gov (United States)

Proposed optical-fiber sensor detects small changes in pressure in elastomeric O-ring or similar pressure seal, which may indicate deterioration of seal and interpreted as indications of incipient failure. According to concept, length of optical fiber embedded in seal. Light-emitting diode illuminates one end of fiber; photodetector measures intensity of light emerging from other end. Pressure-induced changes in seal bend fiber slightly, altering microbending-induced loss of light from fiber and alter intensity of light at photodetector. Change in intensity approximately proportional to change in pressure.

Workman, Gary L.; Kosten, Susan E.

1994-01-01

265

Periodic array of nanoholes on gold-coated optical fiber end-faces for surface plasmon resonance liquid refractive index sensing  

Science.gov (United States)

Focused ion beam (FIB) lithography was used to inscribe a periodic array of nanoholes directly on gold-coated optical fiber end-faces. The excitation of the surface plasmon polaritons of the nanohole arrays on the optical fiber end-faces provided the basis of a refractive index sensor for liquids. This optical fiber based surface plasmon resonance sensor is compact and has the potential to be used in biomedical applications. A sensitivity of approximately 294 nm per refractive index unit (RIU) has been demonstrated for this sensor.

Nguyen, Huy; Sidiroglou, Fotios; Collins, Stephen F.; Baxter, Gregory W.; Roberts, Ann; Davis, Timothy J.

2012-02-01

266

Integrated fiber optic strain sensor  

Science.gov (United States)

This paper investigates a polarimetric fiber optic strain sensor embedded in concrete. A comparison is made between a table version and a recently developed integrated version. The problems and concerns of successfully embedding optical fiber into the harsh cementitious environment are discussed. Experimental data is presented and compared to a simple theoretical model of stress induced birefringence.

Pope, Clark E.; Wu, Sou-Pan; Chuang, Shun-Lien; Calero, Javier; Murtha, Joseph

1992-09-01

267

Fiber optic fire detection technology  

International Nuclear Information System (INIS)

ages 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

268

Polarization-Rotating Sensors Connected To Optical Fibers  

Science.gov (United States)

Proposed optoelectronic sensor system includes polarization-rotating sensing elements interrogated by polarized light transmitted to and from sensing elements along optical fibers. Polarization of light altered by combinations of inherent birefringence, stress-induced birefrigence, and Faraday rotation. Advantages include: light weight, fast response, immunity to electromagnetic interference at radio and lower frequencies, and no need to supply electrical power to sensing elements.

Frazer, Robert E.

1992-01-01

269

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

270

Stress Sensing by an Optical Fiber Sensor: Method and Process for the Characterization of the Sensor Response Depending on Several Designs  

Directory of Open Access Journals (Sweden)

Full Text Available In this paper we propose an analyzing of the response of a stress optical fiber sensor of which we proposed several design. We show that an optical fiber sensor with these designs can covenanting allow the measuring the force/stress applied to a mechanical structure or which it is linked, by optimizing the uses of appropriate materials for constituting the sensor support. The experiment that we introduce to validate our approach based in principles includes design with a support bearing a multimode optical fiber organized in such a way that the transmitted light is attenuated when the fiber-bending angle coming from stitching in holes of the support is modified by the effects of the force/stress applied to the optical fiber sensor realized in this way. The tests realized concern the most relevant parameters that define the performances of the stress sensor that we propose. We present the problems that we to solved for the optimization of the sensor for selecting the more efficient material for the optical fiber sensor support related to a relevant choice of optical fibers.

Mustapha Remouche

2013-06-01

271

Fiber-diffraction Interferometer using Coherent Fiber Optic Taper  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

272

Fiber optics installer and technician guide  

CERN Document Server

For years, fiber optics was the future. Now, it's the present, and the time has come to act if you want to make a career in this fast-growing field. The Fiber Optics Installer and Technician Guide is a comprehensive resource designed to prepare you for the two leading fiber optics certifications, Fiber Optics Installer (FOI) and Fiber Optics Technician (FOT). This book's practical, objective-focused coverage includes:The history of fiber opticsPrinciples of fiber optic transmissionOptical fiber characteristics, construction, and theorySafety considerationsCables, connec

Woodward, Bill

2006-01-01

273

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

274

Refractive index sensing of fiber optic long-period grating structures coated with a plasma deposited diamond-like carbon thin film  

International Nuclear Information System (INIS)

Long-period grating (LPG) structures including cascaded LPGs on step index fibers and photonic crystal fibers were coated with thin films of diamond-like carbon (DLC) using plasma deposition techniques. Improvements in the coating procedures increased sensitivity to external refractive index variations indicating significant improvements in sensing capability of the hybrid structures. DLC films in the range of tens of nanometers significantly increased sensitivity of all the structures tested

275

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

276

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

Directory of Open Access Journals (Sweden)

Full Text Available 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, we review two kinds of typical in-line fiber optic interferometers formed in single-mode fibers fabricated with different post-processing techniques. Also, some recently reported specific technologies for fabricating such fiber optic interferometers are presented.

De-Wen Duan

2012-08-01

277

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.

278

Fabrication and characterization of fiber optical components for application in guiding, sensing and molding of THz and mid-IR radiation  

Science.gov (United States)

The terahertz (THz) range refers to electromagnetic waves with frequencies between 100 GHz and 10 THz, or wavelengths between 3 mm and 30 µm. Light between radio waves and infrared has some unique properties. Within the scope of this work I would like to address three main research topics. In Chapter 2, I describe fabrication method and THz characterization of composite films containing either aligned metallic (tin alloy) microwires or chalcogenide As2Se3 microwires. The microwire arrays are made by stack-and-draw fiber fabrication technique using multi-step co-drawing of low-melting-temperature metals or semiconductor glasses together with polymers. Fibers are then stacked together and pressed into composite films. Transmission through metamaterial films is studied in the whole THz range (0.1-20 THz) using a combination of FTIR and TDS. Metal containing metamaterials are found to have strong polarizing properties, while semiconductor containing materials are polarization independent and could have a designable high refractive index. Using the transfer matrix theory, it was shown how to retrieve the complex polarization dependent refractive index of the composite films. We then detail the selfconsistent algorithm for retrieving the optical properties of the metal alloy used in the fabrication of the metamaterial layers by using an effective medium approximation. Finally, we study challenges in fabrication of metamaterials with sub-micrometer metallic wires by repeated stack-and-draw process by comparing samples made using 2, 3 and 4 consecutive drawings. When using metallic alloys we observe phase separation effects and nano-grids formation on small metallic wires. In Chapter 3, we have studied fabrication and bacteria detection application of the lowloss subwavelength THz microstructured fibers. One of the key difficulties in the design of terahertz waveguides lies in the fact that almost all materials are highly absorbing in the terahertz region. Since the lowest absorption loss occurs in dry gases, an efficient waveguide design must maximize the fraction of power guided in the gas. Different types of THz waveguides have been proposed based on this concept including a subwavelength waveguide featuring a core with a size much smaller than the wavelength of light in which a large fraction of the guided light is found outside of the lossy core region. A practical design of such a waveguide was recently proposed in our research group and presents a subwavelength fiber suspended on thin bridges in the middle of a larger protective tube. Large channels formed by the bridges and a tube make a convenient opto-microfluidic system that is easy to fill with liquid analytes or purge with dry gases. Particularly, the THz subwavelength waveguide used in our experiments features a 150 µm core fiber suspended by three 20 µm-thick bridges in the center of a 5.1 mm diameter tube of 4 cm in length. This waveguide design presents several important advantages for bio-sensing applications. First, the waveguide structure allows direct and convenient access to the fiber core and to the evanescent wave guided around it. Second, the outer cladding effectively isolates the core-guided mode from the surrounding environment, (e.g. fiber holders), thereby preventing the undesirable external perturbations of the terahertz signal. Finally, in Chapter 4, low-loss chalcogenide capillary-based waveguides that operate both in the mid-IR and THz spectral ranges are investigated. Chalcogenide glasses have attracted strong interest in a view of optical applications in the near-IR and mid-IR spectral ranges (1-14 µm) due to their relatively low losses and high nonlinearities. Furthermore, chalcogenide glass-based microstructured fibers open many interesting possibilities for a large number of applications in the mid-IR spectral range, where applications in optical sensing, supercontinuum generation and single-mode propagation of IR light, transmission of the CO and CO2 laser radiation have already been demonstrated. We believe that chalcogenide glasses c

Mazhorova, Anna

279

Classification of Fiber Optical Sensors  

Directory of Open Access Journals (Sweden)

Full Text Available Fiber optics sensor technology offers different parameter measurements such as strain, pressure, temperature, current and many more things. For that different type of sensors are used and these sensors converts these parameters to optical parameters like light intensity or phase or polarization of light. These converted parameters are transmitted using an optical link over a long distance. In this paper, we review optical sensors and their applications. Here, we describe the classification of fiber optic sensors and based on these sensors, some applications of them are discussed.

Shivang Ghetia

2013-07-01

280

Tailored draw tower fiber Bragg gratings for various sensing applications  

Science.gov (United States)

The idea of fabricating fiber Bragg gratings during the drawing process of an optical fiber dates back almost 20 years. The application of a transverse holographic writing method on a fiber draw tower offers a promising solution for a highly effective Bragg grating production. Because of the high technology requirements it took more than 10 years to develop the method into a reliable process. The improvements in the technical development during the last five years enable today a cost efficient industrial production of draw tower grating (DTG®) arrays. In this paper we report about new possibilities of the improved process with respect to the grating type (type I gratings, type II gratings), the coating type (2ORMOCER®, metals) and the fiber diameter (125?m, 80?m and below). Furthermore, we present an example for the application of draw tower fiber Bragg gratings in sensing technologies for medical applications.

Lindner, Eric; Mörbitz, Julia; Chojetzki, Christoph; Becker, Martin; Brückner, Sven; Schuster, Kay; Rothhardt, Manfred; Willsch, Reinhardt; Bartelt, H.

2012-02-01

 
 
 
 
281

Shaping of looped miniaturized chalcogenide fiber sensing heads for mid-infrared sensing.  

Science.gov (United States)

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. PMID:25264953

Houizot, Patrick; Anne, Marie-Laure; Boussard-Plédel, Catherine; Loréal, Olivier; Tariel, Hugues; Lucas, Jacques; Bureau, Bruno

2014-01-01

282

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

283

Silica optical fibers: technology update  

Science.gov (United States)

Silica-core optical fibers have long been the standard delivery medium for medical laser delivery systems. Their high strength, excellent flexibility, and low cost continue to make them the fiber of choice for systems operating from 300 to 2200 nm. An overview of the current fiber constructions available to the industry is reviewed. Silicone-clad fibers, hard- fluoropolymer clad fibers and silica-clad fibers are briefly compared in terms of mechanical and optical properties. The variety of fiber coatings available is also discussed. A significant product development of silica fiber delivery systems has been in side-firing laser delivery systems for Urology. These devices utilize silica-core fibers to project the laser energy at a substantial lateral angle to the conventional delivery system, typically 40 to 100 degrees off axis. Many unique distal tips have been designed to meet the needs of this potentially enormous application. There are three primary technologies employed in side-firing laser delivery systems: reflection off of an attached medium; reflection within an angle-polished fiber through total internal reflection; and reflection from both an angle-polished fiber and an outside medium. Each technology is presented and compared on the basis of operation modality, transmission efficiency, and power-handling performance.

Krohn, David A.; McCann, Brian P.

1995-05-01

284

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.

Yuan, Scott Wu; Bang, Ole

2010-01-01

285

Microbending fiber optic sensors for smart structures  

Science.gov (United States)

Fiber optic smart structures can be used to perform a variety of functions ranging from monitoring the manufacturing process, performing nondestructive evaluation of components once the parts have been made, providing means to implement vehicle health monitoring and maintenance systems, and enabling systems such as actively damped structures and performance monitoring of aircraft engines. This paper describes a low cost approach to microbending sensing and its application to feasibility studies for manufacturing and health maintenance.

Udd, Eric; Theriault, John Paul; Markus, Alan; Bar-Cohen, Yoseph

1990-02-01

286

Multimode optical fiber based spectrometers  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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. ...

Redding, Brandon; Popoff, Sebastien M.; Cao, Hui

2013-01-01

287

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

288

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

289

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

290

System for testing optical fibers  

International Nuclear Information System (INIS)

A system for nondestructively determining the attenuation coefficient, alpha ( Lambda ), of low-loss optical fiber wave guides is described. Cerenkov light pulses are generated at a plurality of locations in the fiber by a beam of charged particles. The transit times of selected spectral components and their intensities are utilized to unfold the alpha ( Lambda ) values over the measured spectrum

291

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

292

Fiber optic diffraction grating maker  

Science.gov (United States)

A compact and portable diffraction grating maker comprised of a laser beam, optical and fiber optics devices coupling the beam to one or more evanescent beam splitters, and collimating lenses or mirrors directing the split beam at an appropriate photosensitive material. The collimating optics, the output ends of the fiber optic coupler and the photosensitive plate holder are all mounted on an articulated framework so that the angle of intersection of the beams can be altered at will without disturbing the spatial filter, collimation or beam quality, and assuring that the beams will always intersect at the position of the plate.

Deason, Vance A. (Idaho Falls, ID); Ward, Michael B. (Idaho Falls, ID)

1991-01-01

293

Classification of Fiber Optical Sensors  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Fiber optics sensor technology offers different parameter measurements such as strain, pressure, temperature, current and many more things. For that different type of sensors are used and these sensors converts these parameters to optical parameters like light intensity or phase or polarization of light. These converted parameters are transmitted using an optical link over a long distance. In this paper, we review optical sensors and their applications. Here, we describe the classification of...

Shivang Ghetia; Ruchi Gajjar; Pujal Trivedi

2013-01-01

294

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

295

Nonlinear effects in optical fibers  

CERN Document Server

This book will provide insight into the principles and applications of nonlinear effects in fibers for students, researchers, and developers who have a basic understanding of electromagnetic theory under their belts.  It will explore the physics, limitations, applications, and research results surrounding nonlinear effects in fiber optics. In addition to communications, optical fibers are already used in medical procedures, automobiles, and aircraft and are expected to have many other applications.  This will expand the range of industry workers who will find a book of this type useful.

Ferreira, Mario F

2011-01-01

296

Supercontinuum Generation in Optical Fibers  

Science.gov (United States)

1. Introduction and history J. R. Taylor; 2. Supercontinuum generation in microstructure fiber - an historical note J. K. Ranka; 3. Nonlinear fiber optics overview J. C. Travers, M. H. Frosz and J. M. Dudley; 4. Fiber supercontinuum generation overview J. M. Dudley; 5. Silica fibers for supercontinuum generation J. C. Knight and W. Wadsworth; 6. Supercontinuum generation and nonlinearity in soft glass fibers J. H. V. Price and D. J. Richardson; 7. Increasing the blue-shift of a picosecond pumped supercontinuum M. H. Frosz, P. M. Moselund, P. D. Rasmussen, C. L. Thomsen and O. Bang; 8. Continuous wave supercontinuum generation J. C. Travers; 9. Theory of supercontinuum and interactions of solitons with dispersive waves D. V. Skryabin and A. V. Gorbach; 10. Interaction of four-wave mixing and stimulated Raman scattering in optical fibers S. Coen, S. G. Murdoch and F. Vanholsbeeck; 11. Nonlinear optics in emerging waveguides: revised fundamentals and implications S. V. Afshar, M. Turner and T. M. Monro; 12. Supercontinuum generation in dispersion varying fibers G. Genty; 13. Supercontinuum generation in chalcogenide glass waveguides Dong-Il Yeom, M. R. E. Lamont, B. Luther Davies and B. J. Eggleton; 14. Supercontinuum generation for carrier-envelope phase stabilization of mode-locked lasers S. T. Cundiff; 15. Biophotonics applications of supercontinuum generation C. Dunsby and P. M. W. French; 16. Fiber sources of tailored supercontinuum in nonlinear microspectroscopy and imaging A. M. Zheltikov; Index.

Dudley, J. M.; Taylor, J. R.

2010-04-01

297

Optical fiber instrumentation and applications  

Science.gov (United States)

Optical fiber-based sensor instrumentation has been used extensively for the measurement of physical observables including strain, temperature and chemical changes in smart materials and smart structures, and have been integrated with MEMS devices to provide multi-measurement capability along the length of a fiber link or network. This plenary paper briefly outlines recent developments in such optical fiber sensor instrumentation. Fiber optic sensors are small in size, immune to electromagnetic interference and can be easily integrated with existing optical fiber hardware nd components that have been developed primarily for use in the larger telecommunications market. Such sensors can be easily multiplexed, resulting in networks that can be used for the health monitoring of large structures, or the real-time monitoring of structural parameters required for structural analysis and control. This paper briefly describes and compares three current fiber sensor configurations that use Fabry-Perot interferometry and fiber Bragg gratings and long-period grating elements to monitor strain, temperature and other parameters. Extensive details concerning additional related work and field test results and applications are discussed in the references.

Claus, Richard O.

1997-11-01

298

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; Jensen, Jesper Bo

2006-01-01

299

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

300

Fiber optic snapshot hyperspectral imager  

Science.gov (United States)

OPTRA is developing a snapshot hyperspectral imager (HSI) employing a fiber optic bundle and dispersive spectrometer. The fiber optic bundle converts a broadband spatial image to an array of fiber columns which serve as multiple entrance slits to a prism spectrometer. The dispersed spatially resolved spectra are then sampled by a two-dimensional focal plane array (FPA) at a greater than 30 Hz update rate, thereby qualifying the system as snapshot. Unlike snapshot HSI systems based on computed tomography or coded apertures, our approach requires only the remapping of the FPA frame into hyperspectral cubes rather than a complex reconstruction. Our system has high radiometric efficiency and throughput supporting sufficient signal to noise for hyperspectral imaging measurements made over very short integration times (design for the fiber optic snapshot HSI system.

Mansur, David J.; Rentz Dupuis, Julia; Vaillancourt, Robert

2012-06-01

 
 
 
 
301

A study on the jacket effect of fiber optic sensors  

Science.gov (United States)

With the rapid development of distributed fiber optic sensor, such as Brillouin Optical Time Domain Reflectometry (BOTDR), much more importance is attached to the performance of optical fiber. As a conductive and sensing element, optical fiber must be protected from damage and meanwhile be sensitive to strain and temperature. Therefore, tight-buffered optical fiber with a jacket is often used in a certain harsh environment instead of ordinary optical fiber. The jacket can protect optical fiber, on the other hand, exert effect on the optical fiber's sensitivity to temperature and strain. In this paper, two types of optical fiber, i.e. with jacket (Type-A) and without jacket (Type-B), were selected to study the jacket effect on strain measurement, and relative experiment schemes and results are present. It is found that the strain of Type-A, measured by BOTDR, changed with time under constant load stretching within 48 hours, while the Type-B kept constant. After that the load was removed to let the fiber relax. After several days, then again loaded and measured. Through three cycles, the strain measurements of the Type-A gradually increased, but the accretions become smaller and smaller. These experiment results indicate that the jacket has the creep deformation that effects the strain measurement.

Ding, Yong; Shi, Bin; Bao, Xiaoyi; Gao, Junqi

2004-11-01

302

Recent Developments Of Optical Fiber Sensors For Automotive Use  

Science.gov (United States)

Optical fiber sensing technologies are expected to apply for many future electronic control systems in automobiles, because of their original outstanding features, such as high noise immunity, high heat resistance, and flexible light propagation paths which can be applicable to measure the movements and directions of the mobiles. In this paper, two typical applications of fiber sensing technologies in automobiles have been described in detail. The combustion flame detector is one of the typical applications of a fiber spectroscopic technology which utilizes the feature of high noise and heat resistibility and remote sensibility. Measurements of engine combustion conditions, such as the detonation, the combustion initiation, and the air-fuel ratio, have been demonstrated in an experimental fiber sensing method. Fiber interferometers, such as a fiber gyroscope, have a lot of possibilities in future mobile applications because they are expandable to many kinds of measurements for movements and physical variables. An optical fiber gyroscope utilizing the single polarized optical fiber and optical devices has been developed. Quite an accurate measurement of vehicle position was displayed on a prototype navigation system which installed the fiber gyroscope as a rotational speed sensor.

Sasayama, Takao; Oho, Shigeru; Kuroiwa, Hiroshi; Suzuki, Seikoo

1987-12-01

303

The use of BOTDR to evaluate the thermal effects on fiber residual strain of optical fiber cables  

Science.gov (United States)

The residual axial strain induced in the cabled fiber is a vital factor to evaluate the reliability of optical fiber cables. However, little is known about the thermal effect on the fiber residual strain, especially on the particular short section of the fiber. In order to precisely determine the thermal effects on fiber residual strain of optical cables, a measurement method based on Brillouin Optical Time-Domain Reflectometry (BOTDR) system is proposed. Thermal characteristics of fiber residual strain of optical fiber cables are investigated theoretically and experimentally. Measurements of the residual strain in particular short section of fiber are made with the distributed fiber sensing system based on BOTDR. Experimental results for a double-coated fiber in loose structure cable are in good agreement with those predicted from the theory. It has been found that the fiber residual strain increases linearly with the decrease of the temperature in the range from 50°C to -50°C.

Lu, Yuangang; Li, Cunlei; Wang, Liang; Zhang, Xuping

2007-11-01

304

Distributed strain measurements in precision-wound optical fibers using Brillouin optical time domain reflectometry  

Science.gov (United States)

In this paper, the nondestructive, nonlinear distributed- strain sensing technique known as Brillouin Optical Time Domain Reflectometry (BOTDR) is described. The strain distributions along optical fibers wound in precision configurations are measured and analyzed using a recently developed commercial-off-the-shelf BOTDR system. Determinations of sensitivity and spatial resolution are made for the instrument. Measurement comparisons to an analytical model are made for the wound fiber packs. Characterizations of measurements of certain geometric configurations and deformity phenomena are expressed. Assessment of the applicability of the technique to reliability predictions for precision-wound fiber optic dispensers and fiber optic gyroscopes is made.

Burgett, Sherrie J.; Light, Robert L.; Ruffin, Paul B.; Counts, Gary J.

1998-07-01

305

Online fiber-optic photometer  

International Nuclear Information System (INIS)

The development and implementation of a fiber-optic photometer for process control at the Savannah River Plant (SRP) will be discussed. The instrument is a modified Du Pont 400 photometric analyzer which incorporates quartz fiber-optic cables, a high-intensity tungsten-halogen lamp source, and a sight glass with sealed optics. Six of these photometers have been installed at SRP to monitor the elution of neptunium or plutonium from anion exchange columns. The fiber optics allow the instrument to be located 50 feet from the sight glass, which is in a highly radioactive area. This ensures easy access to the instrument and minimizes radiation exposure to personnel. The modifications to the analyzer and its application to process control will be presented

306

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

307

Fiber optic chemical sensors: The evolution of high- density fiber-optic DNA microarrays  

Science.gov (United States)

Sensors were developed for multianalyte monitoring, fermentation monitoring, lactate analysis, remote oxygen detection for use in bioremediation monitoring and in a fuel spill clean-up project, heavy metal analysis, and high density DNA microarrays. The major focus of this thesis involved creating and improving high-density DNA gene arrays. Fiber optic sensors are created using fluorescent indicators, polymeric supports, and optical fiber substrates. The fluorescent indicator is entrapped in a polymer layer and attached to the tip of the optical fiber. The tip of the fiber bearing the sensing layer (the distal end) is placed in the sample of interest while the other end of the fiber (the proximal end) is connected to an analysis system. Any length of fiber can be used without compromising the integrity or sensitivity of the system. A fiber optic oxygen sensor was designed incorporating an oxygen sensitive fluorescent dye and a gas permeable polymer attached to an optical fiber. The construction simplicity and ruggedness of the sensor enabled its deployment for in situ chemical oxidation and bioremediation studies. Optical fibers were also used as the substrate to detect biomolecules in solution. To monitor bioprocesses, the production of the analyte of interest must be coupled with a species that is optically measurable. For example, oxygen is consumed in many metabolic functions. The fiber optic oxygen sensor is equipped with an additional sensing layer. Upon contact with a specific biochemical in the sample, a reaction occurs in the additional sensing layer that either consumes or produces oxygen. This dual layer system was used to monitor the presence of lactate, an important metabolite for clinical and bioprocess analysis. In many biological and environmental systems, the generation of one species occurs coincidentally with the generation or consumption of another species. A multianalyte sensor was prepared that can monitor the simultaneous activity of pH, CO2 and O2. This sensor is useful for monitoring bioprocesses such as (beer) fermentation and for clinical situations such as blood gas analysis. DNA sensors were created by attaching short single strands of DNA (probes) to the fiber tip. A matching single strand (target) forms a strong interacting pair with the probe upon contact. The target strands in a sample are labeled with a fluorescent dye. When a probe-target pair is formed and excitation light is sent down the fiber, the fiber bearing the pair emits light that is captured and detected. A high density DNA array was created by isolating thousands of discrete DNA sensors on the tip of an imaging optical fiber. This array was made possible by the formation of microwells on the imaging fiber tip. Microspheres functionalized with DNA were placed in the wells of the fiber and each microsphere was independently and simultaneously monitored. (Abstract shortened by UMI.)

Ferguson, Jane A.

2001-06-01

308

Measuring the Temperature Profile in a Salt-Gradient Solar Pond Using a Fiber-Optic Distributed Temperature Sensing System  

Science.gov (United States)

In shallow aquatical thermohaline environments, such as salt-gradient solar ponds (SGSPs), it is important to measure temperature on fine spatial and temporal scales to detect stratification or different hydrodynamics regimes (e.g., salt fingering, oscillatory motion). The spatial variability of interest in SGSPs is observed on vertical scales of centimeters, whereas the temporal variability can be on time scales ranging from minutes to months, or even years. Measuring temperature at these scales can be difficult because of the cost involved, especially when diel cycles needs to be reported during a long period of time. The Raman spectra distributed temperature sensing (DTS) is an approach available to provide coverage of both “in space” and “in time” for use in aquatic systems. Recently it has been used to measure temperature in streams, lakes, air, snow, and other hydrologic or environmental applications. This work investigates the thermal behavior of an experimental SGSP using a high-vertical resolution DTS system. In the experimental SGSP and DTS system, the vertical temperature profile is monitored each 1.1 cm within the SGSP without disturbing the water column. The air temperature profile over the water surface is also measured with the same spatial resolution. Temperatures collected in electrical conductivity probes are used to compare the DTS measurements. The temperatures measured using the DTS system during the first two weeks of experimentation showed an increase of the temperature from 17 to 34 °C in the lower zone of the SGSP. Also, mixing and stratification were observed in the different zones of the SGSP. In the surface zone, the water mixed during the night and stratified during the day. On the other hand, in the lower zone the mixing was observed during the day and stratification occurred during the night. The results show that DTS systems are highly suitable for measuring temperatures in SGSPs, with resolutions smaller than 0.03 °C on fine spatial and temporal scale.

Suarez, F. I.; Childress, A. E.; Tyler, S. W.

2009-12-01

309

Porous plastic optical fiber sensor for ammonia measurement.  

Science.gov (United States)

A porous plastic optical fiber has been developed for use in chemical gas sensing. This porous plastic waveguide, which was made with copolymer materials, has an interconnective porous structure as well as uniformity of pore size. These sensors are based on in-line optical absorption within the porous plastic fiber core and have much greater sensitivities than sensors based on evanescent coupling to a surrounding medium. Furthermore, this fiber simultaneously exhibits very high gas permeability and liquid impermeability. This combination makes the fiber particularly suitable for gas concentration measurements in aqueous samples. An ammonia gas sensor has been tested to demonstrate the effectiveness of this porous plastic waveguide. PMID:20555459

Zhou, Q; Kritz, D; Bonnell, L; Sigel, G H

1989-06-01

310

A fiber-optic current sensor for aerospace applications  

Science.gov (United States)

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 electromagnetic interference (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. The technology contained in the sensor is examined and the results of precision tests conducted at various temperatures within the wide operating range are given. The results of early EMI tests are also given.

Patterson, Richard L.; Rose, A. H.; Tang, D.; Day, G. W.

1990-01-01

311

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

312

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

313

A fiber optic voltage sensor based on intensity modulation  

Science.gov (United States)

A fiber optic DC voltage sensor based on an intensity modulation scheme is proposed. Fiber optic voltage sensors have the advantage over conventional voltage sensors in that they offer voltage isolation and can easily be incorporated in telecommunication systems. The intensity modulation approach to sensing is a less costly and simpler measurement system compared to other available fiber optic voltage sensor techniques. Intensity modulation is achieved using a piezoelectric ceramic which produces a displacement on application of a voltage varying the transmitted optical power in a fiber to fiber coupling system. A critical analysis was performed on the theory behind the intensity modulation scheme for fiber voltage sensing. Simulations and experimental investigations based on this concept showed good linearity between the applied voltage and optical power in the fiber. The feasibility of obtaining a single valued relationship for voltage sensing purposes was also observed. The constructed voltage sensor produced useful results with the sensor exhibiting good linearity in forward and reverse voltages over a DC voltage of 0V to 100V but exhibited hysteresis. A linearity of 92% and 88.8% was measured for the forward and reverse voltages respectively and a dynamic range of approximately 0.3dB over the 100V range was achieved with a resolution of 1.9V. The hysteresis in the sensor was measured at 20%. Based on the results obtained recommendations have been made on a more linear, lower hysteresis and stable sensor of this type.

Ndiaye, Musa

2014-06-01

314

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

315

Subwavelength and nanometer diameter optical fibers  

CERN Document Server

Subwavelength and Nanometer Diameter Optical Fibers provides a comprehensive and up-to-date coverage of research on nanoscale optical fibers including the basic physics and engineering aspects of the fabrication, properties and applications. The book discusses optical micro/nanofibers that represent a perfect fusion of optical fibers and nanotechnology on subwavelength scale and covers a broad range of topics in modern optical engineering, photonics and nanotechnology spanning from fiber optics, near-field optics, nonlinear optics, atom optics to nanofabrication and microphotonic components/de

Tong, Limin

2011-01-01

316

Fiber optic probes for biomedical optical spectroscopy  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

317

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

318

Thermally regenerated fiber Bragg gratings in twin-air-hole microstructured fibers for high temperature pressure sensing  

Science.gov (United States)

We present thermally regnenerated fiber Bragg grating in air-hole microstructured fibers for high temperature hydrostatic pressure sensing application. Saturated type I gratings were inscribed in hydrogen-loaded two-hole optical fibers using 248-nm KrF laser, and regenerated during annealing at 800ºC. The fiber Bragg grating resonance wavelength shift and peak splits were studied as a function of external hydrostatic pressure from 15 psi to 2400 psi. The grating pressure sensor shows stable and reproducible operation up to 800ºC. This paper demonstrates a multiplexible pressure sensor network technology for high temperature harsh environment using a single fiber feedthrough.

Chen, Tong; Chen, Rongzhang; Jewart, Charles; Zhang, Botao; Canning, John; Cook, Kevin; Chen, Kevin P.

2011-06-01

319

Fiber optic and laser sensors III  

International Nuclear Information System (INIS)

Fiber Optic and Laser Sensors III is the third of a planned series of conferences dealing with state-of-the-art advancement in this technology area. Historically this conference has evolved due to the pioneering work aimed at acoustic and rotation sensing at several government and university laboratories (e.g., Naval Research Laboratory, MIT, and Stanford). At this point, if it can be sensed (temperature, magnetic field, blood pressure, rotation, flow, liquid level, current, voltage, gas and liquid chemistry, etc.) someone is trying to do it with fibers; many of these activities are recorded in this publication. A new activity, broadband sensors, was introduced at this conference; the major thrust is to use the large bandwidth of the optical fiber and conventional sensor to record single occurrence events (e.g., a nuclear explosion). Other important areas of presentation were: stress in composites, distributed sensors, and sensors for biological/medical applications. Although several papers were presented by major industrial companies related to the continuing development of the rotation sensor, the participation was limited by the evolution toward products, a natural path (as new technology progresses research and development become specific to proprietary designs)

320

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

 
 
 
 
321

Feasibility of giant fiber-optic gyroscopes  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

322

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

323

Analytical calculation of motion fiber optic accelerometer ????????????? ?????? ???????? ?????????-??????????? ????????????? ?????????? ?????????? ???????? ?????????-????????? ?????????????  

Digital Repository Infrastructure Vision for European Research (DRIVER)

An analytical calculation of motion fiber optic accelerometer and impact of external destabilizing factors, such as impacts and vibration loads.???????? ????????????? ?????? ???????? ?????????-??????????? ????????????? ? ??????? ??????? ????????????????? ????????, ????? ??? ????? ? ???????????? ????????.????????? ??????????? ...

Chubarev, O. A.; Demjanenko, P. O.

2009-01-01

324

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.

2014-09-09

325

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

326

Catching Attention in Fiber Optics Class  

CERN Document Server

Following a brief review on the history and the current development of fiber optics, the significance of teaching fiber optics for science and non-science major college students is addressed. Several experimental demonstrations designed to aid the teaching and learning process in fiber optics lectures are presented. Sample laboratory projects are also proposed to help the students to understand the physical principles of fiber optics.

Kezerashvili, G Ya

2004-01-01

327

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

328

Optical fibers and RF a natural combination  

CERN Document Server

The optical fiber industry has experienced a period of consolidation and reorganization and is now poised for a new surge in growth. To take advantage of that growth, and to respond to the demand to use fiber more efficiently, designers need a better understanding of fiber optics. Taking the approach that optical fibers are an extension of RF-based communications, the author explains basic optical concepts, applications, and systems; the nature and performance characteristics of optical fibers; and optical sources, connectors and splices. Subsequent chapters explore current applications of fib

Romeiser, Malcolm

2004-01-01

329

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; Bang, Ole

2013-01-01

330

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

331

Surface plasmon resonance based multi-channel and multi-analyte fiber optic sensor  

Science.gov (United States)

Surface plasmon resonance (SPR) based fiber optic sensor has been studied for multichannel and multianalyte sensing. Simulations have been carried out for a fiber optic sensor having two sensing regions coated with silver and gold for multichannel and multianalyte sensing. The simulated results have been obtained for different combinations of refractive indices of the samples around the probes. To support simulations optical fiber SPR probes with two sensing regions coated with silver and gold have been fabricated. SPR spectra for these sensors have been recorded for aqueous sucrose solutions of varying refractive indices. The refractive index of the liquid samples around both the gold and silver coated regions was kept the same to see the potential of SPR based fiber optic multichannel sensing, while it was kept different for studies related to multianalyte sensing. Both the theoretical and experimental results match qualitatively. The SPR resonance wavelengths for gold and silver being different, these sensors can be utilized for both multichannel and multianalyte sensing.

Verma, Roli; Srivastava, Sachin K.; Gupta, Banshi D.

2012-02-01

332

A Smart Graded-index Multimode Fiber Based Sensor Unit for Multi-parameter Sensing Applications  

Directory of Open Access Journals (Sweden)

Full Text Available We demonstrate a smart optical fiber sensor unit to realize a multi-parameter sensing, including temperature, curvature and strain or displacement. The sensor unit is composed of a Bragg grating in graded-index multimode fiber and a Fizeau cavity.

Shuo Fang

2013-06-01

333

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

334

Design and optimization of microstructured optical fiber sensors  

Science.gov (United States)

The integration of sensor networks into large civil and mechanical structures is becoming an important engineering practice to ensure the structural health of important infrastructure and power generation facilities. The temperature, pressure, and internal stress distribution within the structures are key parameters to monitor the structural health of a system. Optical fiber sensors are one of the most common sensing elements used in the structural health monitoring due to their compact size, low cost, electrical immunity, and multiplexing ability. In this dissertation, the design and optimization of air-hole microstructured optical fibers for use as application specific sensors is presented. Air hole matrices are used to design fiber cores with a large birefringence; while air hole arrays within the fiber cladding are studied and optimized to engineer unique geometries that can give desired sensitivity and directionality of the fiber sensors. A pure silica core microstructured photonic crystal fiber was designed for hydrostatic pressure sensing. The impact of the surrounding air-holes to the propagation mode profiles and indices were studied and improved. To improve directionality and sensitivity of fiber sensors, air holes in the fiber cladding were implemented and optimized in the design of the fiber. Finite element analysis simulations were performed to elicit the correlation between air-hole configuration and the fiber sensor's performance and impact of the fiber's opto-mechanic properties. To measure pressure and stress at high temperature, an ultrafast laser was used to inscribe type II gratings in two-hole microstructured optical fibers and suspended core fibers. The fiber Bragg grating resonance wavelength shift and peak splitting were studied as a function of external pressure, bending, and lateral compression. Fiber sensors in two-hole fibers show stable and reproducible operation above 800°C. Fiber grating sensor in suspended core fibers exhibits high directionality to transverse stress, and insensitivity to bending. All experimental results are in good agreement with the simulations. This works demonstrates that ingenious design and engineering of air hole matrices in optical fiber's cladding and core can lead to multi-functional and multiplexable fiber sensors that were previously unattainable using traditional solid-core solid cladding fiber.

Jewart, Charles Milford

335

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

336

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."

2014-09-02

337

Glass-ceramic fiber optic sensors  

Science.gov (United States)

Optical fibers with layers of glass-ceramics are considered and tested with respect to their use in different environments as single- and multimode lightguides. Glass-ceramic optical fibers are tested that have different material compositions, cross-section topologies, and coefficients of thermal expansion (CTEs). Stress-induced optical phase-temperature effects can be studied with glass ceramics that have CTEs of around zero, and the glass ceramic sensors are compared to nontreated fibers to study the dependencies of the fibers' parameters on induced stress and temperature. The application of glass-ceramics with various values of linear CTE to the fibers is studied to scale the characteristics of a glass-ceramic fiber-optic thermometer for several temperature ranges. The sensor can be stabilized when the pure stress-temperature effect is isolated. These glass-ceramic optical fibers are shown to provide unique characteristics for the use of fiber-optic measuring devices in certain measurement environments.

Romaniuk, Ryszard S.; Stepien, Ryszard

1991-03-01

338

[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

339

Advanced fiber optic seismic sensors (geophone) research  

Science.gov (United States)

The systematical research on the fiber optic seismic sensors based on optical Fiber Bragg Grating (FBG) sensing technology is presented in this thesis. Optical fiber sensors using fiber Bragg gratings have a number of advantages such as immunity to electromagnetic interference, lightweight, low power consumption. The FBG sensor is intrinsically sensitive to dynamic strain signals and the strain sensitivity can approach sub micro-strain. Furthermore, FBG sensors are inherently suited for multiplexing, which makes possible networked/arrayed deployment on a large scale. The basic principle of the FBG geophone is that it transforms the acceleration of ground motion into the strain signal of the FBG sensor through mechanical design, and after the optical demodulation generates the analog voltage output proportional to the strain changes. The customized eight-channel FBG seismic sensor prototype is described here which consists of FBG sensor/demodulation grating pairs attached on the spring-mass mechanical system. The sensor performance is evaluated systematically in the laboratory using the conventional accelerometer and geophone as the benchmark, Two major applications of FBG seismic sensor are demonstrated. One is in the battlefield remote monitoring system to detect the presence of personnel, wheeled vehicles, and tracked vehicles. The other application is in the seismic reflection survey of oilfield exploration to collect the seismic waves from the earth. The field tests were carried out in the air force base and the oilfield respectively. It is shown that the FBG geophone has higher frequency response bandwidth and sensitivity than conventional moving-coil electromagnetic geophone and the military Rembass-II S/A sensor. Our objective is to develop a distributed FBG seismic sensor network to recognize and locate the presence of seismic sources with high inherent detection capability and a low false alarm rate in an integrated system.

Zhang, Yan

340

A Large Area Fiber Optic Gyroscope on multiplexed fiber network  

CERN Document Server

We describe a fiber optical gyroscope based on the Sagnac effect realized on a multiplexed telecom fiber network. Our loop encloses an area of 20 km^2 and coexists with Internet data traffic. This Sagnac interferometer achieves a sensitivity of about 1e-8 (rad/s)/sqrt(Hz), thus approaching ring laser gyroscopes without using narrow-linewidth laser nor sophisticated optics. The proposed gyroscope is sensitive enough for seismic applications, opening new possibilities for this kind of optical fiber sensors

Clivati, Cecilia; Costanzo, Giovanni A; Mura, Alberto; Pizzocaro, Marco; Levi, Filippo

2012-01-01

 
 
 
 
341

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

342

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

343

Fiber optic fugitive emission dosimeter  

Science.gov (United States)

Federal regulations require companies to monitor leaks from valves, flanges, and pipes (fugitive emissions) in industrial plants on a regular basis. Honeywell has been conducting research into the use of fiber optic sensors for this purpose. The result ia a low-cost chemical dosimeter that is able to detect a variety of fugitive emissions, including various volatile organic compounds (VOCs) down to a few hundred parts per million (ppm). This sensor uses a fluorescent dye that exhibits spectral shifts when its chemical environment is changed. Greater stability is achieved because a spectral change is monitored and the sensor is not dependent on a single relative intensity measurement. Dyes are integrated into an optically clear polymer and immobilized on the tip of an optical fiber. When an analyte permeates into the polymer, a chemical interaction takes place that changes the dye's environment and therefore its spectral fluorescence. With most chemicals of interest, this is a reversible effect. Using a 'smart signal processor' (SSP), a real-time analysis can be made at a distant location. This paper discusses the details and results of a fiber optic sensor incorporating these concepts.

Peck, John; Wilson, Mark L.; Rhodes, Michael L.

1996-12-01

344

Generalized fiber Fourier optics.  

Science.gov (United States)

A twofold generalization of the optical schemes that perform the discrete Fourier transform (DFT) is given: new passive planar architectures are presented where the 2 × 2 3 dB couplers are replaced by M × M hybrids, reducing the number of required connections and phase shifters. Furthermore, the planar implementation of the discrete fractional Fourier transform (DFrFT) is also described, with a waveguide grating router (WGR) configuration and a properly modified slab coupler. PMID:21686007

Cincotti, Gabriella

2011-06-15

345

Fire monitoring system by fiber optic temperature laser radar (FTR)  

Energy Technology Data Exchange (ETDEWEB)

Coal Mining Research Centre, Japan has developed an innovative mine fire monitoring system, which can continuously measure temperature distribution along optical fiber. This paper describes the principle of measuring method, system composition, measuring performance, and results of field test. This system using fiber optic temperature laser radar (FTR) consists of an optical fiber for sensing, measuring units, and a personal computer to calculate and display temperature distribution. Since measuring distance is approximately 2km, the system is suitable to monitor a long roadway. Measuring time is 90 seconds for 2km, accuracy is [plus minus]1 centigrade, and response distance is 1 meter. An optical fiber is intrinsically safe and non-electromagnetic interference, and can bring a lot of information concerning temperature distribution. Therefore, it was demonstrated that the present system can be applied to monitoring abnormal heating and to predicting fire spot. 2 refs., 12 figs.

Sugiuchi, S.; Yamashita, E.; Sakai, T. (The Coal Mining Research Center, Tokyo (Japan))

1993-09-01

346

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

347

Extrinsic fiber-optic Fabry-Perot interferometer sensor for refractive index measurement of optical glass  

Energy Technology Data Exchange (ETDEWEB)

A simple fiber-optic sensor based on Fabry-Perot interference for refractive index measurement of optical glass is investigated both theoretically and experimentally. A broadband light source is coupled into an extrinsic fiber Fabry-Perot cavity formed by the surfaces of a sensing fiber end and the measured sample. The interference signals from the cavity are reflected back into the same fiber. The refractive index of the sample can be obtained by measuring the contrast of the interference fringes. The experimental data meet with the theoretical values very well. The proposed technique is a new method for glass refractive index measurement with a simple, solid, and compact structure.

Chen Jihuan; Zhao Jiarong; Huang Xuguang; Huang Zhenjian

2010-10-10

348

Fiber-optic communication systems  

CERN Document Server

This book provides a comprehensive account of fiber-optic communication systems. The 3rd edition of this book is used worldwide as a textbook in many universities. This 4th edition incorporates recent advances that have occurred, in particular two new chapters. One deals with the advanced modulation formats (such as DPSK, QPSK, and QAM) that are increasingly being used for improving spectral efficiency of WDM lightwave systems. The second chapter focuses on new techniques such as all-optical regeneration that are under development and likely to be used in future communication systems. All othe

Agrawal, Govind P

2010-01-01

349

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

350

Distributed fiber optic fuel leak detection system  

Science.gov (United States)

With the increase worldwide demand for hydrocarbon fuels and the vast development of new fuel production and delivery infrastructure installations around the world, there is a growing need for reliable fuel leak detection technologies to provide safety and reduce environmental risks. Hydrocarbon leaks (gas or liquid) pose an extreme danger and need to be detected very quickly to avoid potential disasters. Gas leaks have the greatest potential for causing damage due to the explosion risk from the dispersion of gas clouds. This paper describes progress towards the development of a fast response, high sensitivity, distributed fiber optic fuel leak detection (HySensTM) system based on the use of an optical fiber that uses a hydrocarbon sensitive fluorescent coating to detect the presence of fuel leaks present in close proximity along the length of the sensor fiber. The HySenseTM system operates in two modes, leak detection and leak localization, and will trigger an alarm within seconds of exposure contact. The fast and accurate response of the sensor provides reliable fluid leak detection for pipelines, tanks, airports, pumps, and valves to detect and minimize any potential catastrophic damage.

Mendoza, Edgar; Kempen, C.; Esterkin, Yan; Sun, Sunjian

2013-05-01

351

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

352

Fiber Optic Pressure Sensor using Multimode Interference  

International Nuclear Information System (INIS)

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.

353

Use of optical fibers in spectrophotometry  

Science.gov (United States)

The use of single or small numbers of fiber optic fibers in astronomical spectroscopy with the goal of greater spectrophotometric and radial velocity accuracy is discussed. The properties of multimode step index fibers which are most important for this application are outlined, as are laboratory tests of currently available fibers.

Ramsey, Lawrence W.

1988-01-01

354

Fiber-optic voltage sensor with cladded fiber and evanescent wave variation detection  

Science.gov (United States)

A fiber optic voltage sensor is described which includes a source of light, a reference fiber for receiving a known percentage of the light and an electrostrictive element having terminals across which is applied, a voltage to be measured. The electrostrictive element is responsive to the applied voltage to assume an altered physical state. A measuring fiber also receives a known percentage of light from the light source and is secured about the electrostrictive element. The measuring fiber is provided with a cladding and exhibits an evanescent wave in the cladding. The measuring fiber has a known length which is altered when the electrostrictive element assumes its altered physical state. A differential sensor is provided which senses the intensity of light in both the reference fiber and the measuring fiber and provides an output indicative of the difference between the intensities. 3 figs.

Wood, C.B.

1992-12-15

355

Distributed fiber-optic laser-ultrasound generation based on ghost-mode of tilted fiber Bragg gratings.  

Science.gov (United States)

Active ultrasonic testing is widely used for medical diagnosis, material characterization and structural health monitoring. Ultrasonic transducer is a key component in active ultrasonic testing. Due to their many advantages such as small size, light weight, and immunity to electromagnetic interference, fiber-optic ultrasonic transducers are particularly attractive for permanent, embedded applications in active ultrasonic testing for structural health monitoring. However, current fiber-optic transducers only allow effective ultrasound generation at a single location of the fiber end. Here we demonstrate a fiber-optic device that can effectively generate ultrasound at multiple, selected locations along a fiber in a controllable manner based on a smart light tapping scheme that only taps out the light of a particular wavelength for laser-ultrasound generation and allow light of longer wavelengths pass by without loss. Such a scheme may also find applications in remote fiber-optic device tuning and quasi-distributed biochemical fiber-optic sensing. PMID:23482179

Tian, Jiajun; Zhang, Qi; Han, Ming

2013-03-11

356

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

357

The Effects of High Temperature and Nuclear Radiation on the Optical Transmission of Silica Optical Fibers  

Science.gov (United States)

Distributed measurements made with fiber optic instrumentation have the potential to revolutionize data collection for facility monitoring and process control in industrial environments. Dozens of sensors etched into a single optical fiber can be used to instrument equipment and structures so that dozens of spatially distributed temperature measurements, for example, can be made quickly using one optical fiber. Optically based sensors are commercially available to measure temperature, strain, and other physical quantities that can be related to strain, such as pressure and acceleration. Other commercially available technology eliminates the need to etch discrete sensors into an optical fiber and allows temperature measurements to be made along the length of an ordinary silica fiber. Distributed sensing with optical instrumentation is commonly used in the petroleum industry to measure the temperature and pressure profiles in down hole applications. The U.S. Department of Energy is interested in extending the distributed sensing capabilities of optical instrumentation to high temperature reactor radiation environments. For this technology extension to be possible, the survivability of silica optical fibers needed to be determined in this environment. In this work the optical attenuation added to silica optical fiber exposed simultaneously to reactor radiation and temperatures to 1000°C was experimentally determined. Optical transmission measurements were made in-situ from 400nm-2300nm. For easy visualization, all of the results generated in this work were processed into movies that are available publicly [1]. In this investigation, silica optical fibers were shown to survive optically and mechanically in a reactor radiation environment to 1000°C. For the combined high temperature reactor irradiation experiments completed in this investigation, the maximum attenuation increase in the low-OH optical fibers was around 0.5db/m at 1550nm and 0.6dB/m at 1300nm. The radiation induced optical attenuation primarily affected wavelengths less than 1000nm and this attenuation cannot be avoided in silica. Thermal effects dominated the increase in attenuation at wavelengths above 1000nm and it may be possible to mitigate these effects. Fortuitously, commercial optical instrumentation typically utilizes wavelengths centered around 1300nm and 1550nm where the radiation induced attenuation was minimal. The maximum continuous use temperature of silica optical fiber may be limited to 900°C with intermittent use to 1000°C. The silica optical fibers tested in this project are inexpensive and commercially available. Optical sensors were not tested in this project and development and testing of radiation hard optical sensors is recommended as future work.

Hawn, David P.

358

Optical fiber sensor for membrane submicrometer vibration measurement.  

Science.gov (United States)

This paper presents an optical fiber sensor for membrane submicrometer vibration measurement. The sensor is designed ultimately for low-cost medical audiometric applications such as determining the mobility of the tympanic membrane stimulated by the tone. The sensing method is minimally invasive, and the sensing head does not contact the surface of the membrane. Measurements were performed on tympanic membrane phantoms. Deflections of a few nanometers were measured, and vibration maps of phantoms were taken. PMID:25321687

Prokopczuk, Krzysztof; Rozwadowski, Krzysztof; Aleksandra Starzy?ska, M D; Doma?ski, Andrzej W

2014-09-10

359

Overview Of Fiber-Optic Sensor Systems (FOSS)  

Science.gov (United States)

Fiber-Optic Sensors appear suitable for successfully fulfilling a wide spectrum of sensing transducer requirements in industrial and military applications. Before they supercede existing sensors, a large amount of materials, subsystem and system design research must be accomplished to solve the apparent difficulties. This paper summarizes their promise, the technological problems that arise, and the principle approaches that will solve these problems.

Winsor, Harry V.

1981-02-01

360

Transmission losses in ?-irradiated PCS optical fibers  

International Nuclear Information System (INIS)

Transmission losses in ?-irradiated PCS optical fibers were measured during and after irradiation. Their dependence on the jacket materials was investigated and the effect is explained by the formation of a space charge in the fiber. (author)

 
 
 
 
361

Remotely readable fiber optic compass  

Science.gov (United States)

A remotely readable fiber optic compass. A sheet polarizer is affixed to a magnet rotatably mounted in a compass body, such that the polarizer rotates with the magnet. The optical axis of the sheet polarizer is preferably aligned with the north-south axis of the magnet. A single excitation light beam is divided into four identical beams, two of which are passed through the sheet polarizer and through two fixed polarizing sheets which have their optical axes at right angles to one another. The angle of the compass magnet with respect to a fixed axis of the compass body can be determined by measuring the ratio of the intensities of the two light beams. The remaining ambiguity as to which of the four possible quadrants the magnet is pointing to is resolved by the second pair of light beams, which are passed through the sheet polarizer at positions which are transected by two semicircular opaque strips formed on the sheet polarizer. The incoming excitation beam and the four return beams are communicated by means of optical fibers, giving a remotely readable compass which has no electrical parts.

Migliori, Albert (Santa Fe, NM); Swift, Gregory W. (Los Alamos, NM); Garrett, Steven L. (Pebble Beach, CA)

1986-01-01

362

Interferometric closed-loop fiber-optic gyroscopes  

Science.gov (United States)

The operation of Fiber Optic Gyro is based on the Sagnac Effect which states that light beams propagating along opposite directions in a rotating frame experience an optical path length difference. These two counter-propagating waves propagate within a closed fiber coil, and when this coil rotates the resultant phase difference is proportional to the rotation rate ?. Fiber optic gyroscopes are desirable devices for many navigation and guidance applications because, being solid state devices, they have several major advantages including light weight, long working lifetimes, no moving parts and operate using low voltage power. In this paper the Optolink's single-axis and three-axis fiber optic gyroscopes are described. The Optolink's FOGs consist of the light-emitting diode, one or three photodetectors, circulators and polarization maintaining fiber couplers to divide the light into two or three parts, one or three sets of ring interferometers to sense one or three orthogonal angular rates, and installed PCB signal processing circuits. The ring interferometer consists of a multifunction integrated optic chip and polarization maintaining fiber coil, both these components are designed and fabricated by Optolink. The results illustrate the versatility of the technology, showing its potential to meet both the low-cost, compact sized needs of tactical guidance, as well as the very high performance needs of inertial navigation and precision applications. The optic and electronic blocks of closed-loop gyroscopes with integrated optic components are also considered in this paper.

Korkishko, Yuri N.; Fedorov, Vyacheslav &.; Prilutskii, Victor &.; Ponomarev, Vladimir G.; Morev, Ivan V.; Kostritskii, Sergey M.

2012-02-01

363

Development of radiation resistant optical fibers  

Energy Technology Data Exchange (ETDEWEB)

Radiation resistant optical fibers which can be used in radiation environments such as nuclear power stations have been developed. The developed fibers include the step-index F-doped silica cladded pure silica core fiber and the graded-index F-doped silica core fiber for broad bandwidth. Particularly the former type exhibited superior radiation resistance characteristics chiefly because it contains no impurities in its core. This report describes the results of the optical transmission properties evaluations performed on these types of optical fibers by irradiating ..gamma..-ray and neutron flux on them, in comparison with the Ge doped silica core fibers used for general optical communication purposes. An optical fibers sheathed with thermal-resistant, flameretardant fluorocarbon polymer resin was developed and its feasibility under radiation environments was demonstrated especially in respect to mechanical strength.

Mukunashi, Hiroaki; Watanabe, Minoru; Tanaka, Gotaro; Kameo, Yuji; Kyoto, Michihisa (Sumitomo Electric Industries Ltd., Osaka (Japan))

1983-09-01

364

The Development of Advanced Optical Fibers for Long-Wave Infrared Transmission  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Long-wave infrared fibers are used in an increasing number of applications ranging from thermal imaging to bio-sensing. However, the design of optical fiber with low-loss in the far-infrared requires a combination of properties including good rheological characteristics for fiber drawing and low phonon energy for wide optical transparency, which are often mutually exclusive and can only be achieved through fine materials engineering. This paper presents strategies for obtaining low loss fiber...

Pierre Lucas; Catherine Boussard-Pledel; Allison Wilhelm; Sylvain Danto; Xiang-Hua Zhang; Patrick Houizot; Sebastien Maurugeon; Clément Conseil; Bruno Bureau

2013-01-01

365

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

366

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

367

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

368

Fiber optic neutron imaging system: calibration  

International Nuclear Information System (INIS)

Two neutron imaging experiments using fiber optics have been performed at the Nevada Test Site. In each experiment, an array of scintillator fluor tubes is exposed to neutrons. Light is coupled out through radiation resistant PCS fibers (8-m long) into high-bandwidth, graded index fibers. For image reconstruction to be accurate, common timing differences and transmission variations between fiber optic channels are needed. The calibration system featured a scanning pulsed dye laser, a specially designed fiber optic star coupler, a tektronix 7912AD transient digitizer, and a DEC PDP 11/34 computing system

369

Fiber Optic Gyro Markets And Applications  

Science.gov (United States)

Fiber optic gyroscope (FOG) development current status is reviewed and summarized. These FOG categories are reviewed: •All-Fiberfiber - plus - bulk opticsFiber - plus IOC US development funding of these gyros, segmented into internal R&D and government funding, is forecasted, 1986-1996. The US production of fiber optic gyroscopes is forecasted, 1986-1996. The forecast is segmented into repeatibility rate categories and related applications, and includes both quantity and value data. Component price trends are forecasted. The trend to operation at 1.3-1.6 microns is forecasted.

Montgomery, Jeff D.

1987-03-01

370

Fiber Optic Gyroscope Review And Market Forecast  

Science.gov (United States)

Fiber optic gyroscope 1984 development status is reviewed and summarized. The compan-ies, agencies and universities involved in this development are listed, and leaders are discussed. Included in the review are these gyro categories: All-fiber Fiber - plus - bulk optics Fiber - plus IOC The US funding of development of fiber optic gyros, segmented into internal R&D and government funding, is forecasted, 1984-1994. The US production of fiber optic gyroscopes is forecasted, year by year, 1984-1994. The forecast is segmented into repeatability rate categories and related applications, and includes both quantity and value data. Fiber optic gyro forecasted production is contrasted to spinning mass and ring laser gyroscope demand. Currently available fiber optic components for gyroscope use are reviewed, and performance advances of these components are forecasted. Component price trends are fore-casted. Components discussed include: Single mode fiber - Unipolarized fiber - Conventional single mode - Polarization maintaining Emitters and detectors Couplers Other fiber components Integrated optic circuits The trend to operation at 1.3-1.6 microns is forecasted. Component performance in the 1.3-1.6 micron range is projected. Component suppliers are listed.

Montgomery, Jeff D.

1984-09-01

371

Single-crystal fiber optics: a review  

Science.gov (United States)

Single-crystal (SC) fiber optics have been grown for many years for use as passive fibers for the delivery of IR laser radiation and as active fibers useful as minirod lasers. Most of the early work on SC fiber optics involved the growth of unclad sapphire fibers for the transmission of Er:YAG laser radiation at 2.94 ?m. More recently there has been a renewed interest in rare-earth (RE) doped oxide crystal fibers for use as high power fiber lasers. By analogy with RE doped-bulk laser crystals it is expected that pure YAG and other crystalline SC fibers should be capable of transmitting extremely high laser energies. SC oxide fibers have some distinct advantages over conventional glass fibers including higher thermal conductivity and low stimulated Brillouin scattering (SBS) gain coefficients. The latter can limit the ultimate power output of glass fiber lasers. To date most of the investigators have used the technique of Laser Heated Pedestal Growth (LHPG) to grow unclad SC fibers with diameters ranging from 30 to 350 ?m and in lengths as long as 5 m. The loss for SC sapphire fibers at 2.94 ?m has been measured as low as 0.3 dB/m. In this review we discuss the technique of LHPG, the various SC fiber optics that have been grown for both active and passive applications, and methods that may be used to clad the fibers.

Harrington, James A.

2014-02-01

372

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

373

Engineering metal oxide nanostructures for the fiber optic sensor platform.  

Science.gov (United States)

This paper presents an effective integration scheme of nanostructured SnO2 with the fiber optic platform for chemical sensing applications based on evanescent optical interactions. By using a triblock copolymer as a structure directing agent as the means of nano-structuring, the refractive index of SnO2 is reduced from >2.0 to 1.46, in accordance with effective medium theory for optimal on-fiber integration. High-temperature stable fiber Bragg gratings inscribed in D-shaped fibers were used to perform real-time characterization of optical absorption and refractive index modulation of metal oxides in response to NH3 from the room temperature to 500 °C. Measurement results reveals that the redox reaction of the nanostructured metal oxides exposed to a reactive gas NH3 induces much stronger changes in optical absorption as opposed to changes in the refractive index. Results presented in this paper provide important guidance for fiber optic chemical sensing designs based on metal oxide nanomaterials. PMID:24663558

Poole, Zsolt L; Ohodnicki, Paul; Chen, Rongzhang; Lin, Yuankun; Chen, Kevin P

2014-02-10

374

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

375

Interferometric microstructured polymer optical fiber ultrasound sensor for optoacoustic endoscopic imaging in biomedical applications  

DEFF Research Database (Denmark)

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. © 2014 SPIE.

Gallego, Daniel; Sáez-Rodríguez, David

2014-01-01

376

Evanescent-wave infrared fiber optic biosensor  

Science.gov (United States)

An infrared fiber-optic neurotoxin biosensor was constructed by applying a biologically active cladding to the core of an infrared transmitting chalcogenide fiber. Binding of the surface bound receptor protein was monitored by performing infrared difference spectroscopy on the fiber-optic probe before and after its exposure to various concentrations of neurotoxin in solution. Signals measuring conformational change(s) as a result of these interactions are observed to saturate in agreement with established biochemical kinetics for the receptor. Fiber-optic components are shown to be much more sensitive than bulk optical components in performing these measurements.

de Rochemont, L. P.; Downer, Nancy W.; May, Timothy E.; Smith, H. G.; Oakes, Carlton E.; Ertan-Lamontagne, Marc E.

1993-04-01

377

Brillouin Corrosion Expansion Sensors for Steel Reinforced Concrete Structures Using a Fiber Optic Coil Winding Method  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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; Peng Gong; Xuefeng Zhao

2011-01-01

378

Wavefront sensing reveals optical coherence  

CERN Document Server

Wavefront sensing is a set of techniques providing efficient means to ascertain the shape of an optical wavefront or its deviation from an ideal reference. Due to its wide dynamical range and high optical efficiency, the Shack-Hartmann is nowadays the most widely used of these sensors. Here, we show that it actually performs a simultaneous measurement of position and angular spectrum of the incident radiation and, therefore, when combined with tomographic techniques previously developed for quantum information processing, the Shack-Hartmann can be instrumental in reconstructing the complete coherence properties of the signal. We confirm these predictions with an experimental characterization of partially coherent vortex beams, a case that cannot be treated with the standard tools. This seems to indicate that classical methods employed hitherto do not fully exploit the potential of the registered data.

Stoklasa, B; Rehacek, J; Hradil, Z; Sanchez-Soto, L L

2014-01-01

379

Internally sensed optical phased array.  

Science.gov (United States)

Extending phased array techniques to optical frequencies is challenging because of the considerably smaller wavelengths and the difficulty of stabilizing the optical path lengths of multiple emitters to this level of precision. This is especially true under real-world conditions where thermal and vibrational disturbances cause path length variations that are considerable in relation to the wavelength. Earlier attempts have relied on an external mechanism to sense and compensate for any unwanted variations in the outgoing beams. Here we propose and demonstrate a method that does not rely on any external components. The method combines a pseudo-random noise phase modulation scheme together with conventional heterodyne interferometry to simultaneously measure phase variations between emitters. This information is then used to control the relative phases between the emitters and compensate for any unwanted disturbance. Experimental results are presented that support the viability of this design. PMID:23546269

Bowman, David J; King, Malcolm J; Sutton, Andrew J; Wuchenich, Danielle M; Ward, Robert L; Malikides, Emmanuel A; McClelland, David E; Shaddock, Daniel A

2013-04-01

380

Enhancing Optical Communications with Brand New Fibers  

DEFF Research Database (Denmark)

Optical fibers have often been considered to offer effectively infinite capacity to support the rapid traffic growth essential to our information society. However, as demand has grown and technology has developed, we have begun to realize that there is a fundamental limit to fiber capacity of ~ 100 Tb/s per fiber for systems based on conventional single-core single-mode optical fiber as the transmission medium. This limit arises from the interplay of a number of factors including the Shannon limit, optical fiber nonlinearities, the fiber fuse effect, as well as optical amplifier bandwidth. This article reviews the most recent research efforts around the globe launched over the past few years with a view to overcome these limitations and substantially increase capacity by exploring the last degree of freedom available: the spatial domain. Central to this effort has been the development of brand new fibers for space-division multiplexing and mode-division multiplexing.

Morioka, Toshio

2012-01-01

 
 
 
 
381

Interfacial characterization of soil-embedded optical fiber for ground deformation measurement  

Science.gov (United States)

Recently fiber-optic sensing technologies have been applied for performance monitoring of geotechnical structures such as slopes, foundations, and retaining walls. However, the validity of measured data from soil-embedded optical fibers is strongly influenced by the properties of the interface between the sensing fiber and the soil mass. This paper presents a study of the interfacial properties of an optical fiber embedded in soil with an emphasis on the effect of overburden pressure. Laboratory pullout tests were conducted to investigate the load-deformation characteristics of a 0.9 mm tight-buffered optical fiber embedded in soil. Based on a tri-linear interfacial shear stress-displacement relationship, an analytical model was derived to describe the progressive pullout behavior of an optical fiber from soil matrix. A comparison between the experimental and predicted results verified the effectiveness of the proposed pullout model. The test results are further interpreted and discussed. It is found that the interfacial bond between an optical fiber and soil is prominently enhanced under high overburden pressures. The apparent coefficients of friction of the optical fiber/soil interface decrease as the overburden pressure increases, due to the restrained soil dilation around the optical fiber. Furthermore, to facilitate the analysis of strain measurement, three working states of a soil-embedded sensing fiber were defined in terms of two characteristic displacements.

Zhang, Cheng-Cheng; Zhu, Hong-Hu; Shi, Bin; She, Jun-Kuan

2014-09-01

382

Fiber-optic rotation sensors  

Science.gov (United States)

Possible approaches to the design of fiber optic inertial frame rotation sensors based on the Sagnac effect are reviewed under two general categories: (1) single frequency interferometers which generate a phase shift proportional to inertial rotation rate, and (2) dual frequency interferometers for which the beat frequency is proportional to rotation rate. The principal variations within the single frequency class involve the way in which the nonreciprocal phase bias is used and techniques for generating the nonreciprocal bias. Within the dual frequency class, the various approaches differ principally in the way in which the counter-circulating frequencies are established.

Goss, W. C.

1980-01-01

383

Optical fiber refractometer based on cladding-mode Bragg grating.  

Science.gov (United States)

We demonstrate an optical fiber refractometer based on a cladding-mode Bragg grating. It consists of a long-period grating (LPG) followed by a fiber Bragg grating (FBG). The LPG partially couples light from the core mode to a cladding mode, both of which are reflected by the FBG. Part of the cladding mode reflection is coupled back to the core mode through the original LPG and used for refractive index sensing. The core mode reflection is used to compensate for the temperature cross sensitivity of the refractometer. The sensors operate in the reflection mode and can be multiplexed on a fiber in wavelength domain. PMID:20125734

Han, Ming; Guo, Fawen; Lu, Yongfeng

2010-02-01

384

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

385

Photonic crystal fiber modal interferometer for refractive index sensing of glycerine solution  

Science.gov (United States)

A photonic crystal fiber sensor was prepared for refractive index sensing. Based on modal interferometer theory, the relationships between the refractive index of glycerine solution and resonant wavelength shift of the sensor are analyzed by numerical simulation. A fiber optical device was designed to operate the sensing experiment. The sensing experiment shows that the resonant wavelength blued-shift for the sensor with refractive index in the range of 1.33~1.41 happens when increasing glycerine solution from 0.0% to 50.0% (v/v). The experimental results are approximately consistent with theory.

Huang, Jing; Li, Xueming; Yang, Jianchun

2013-12-01

386

SPR based three channels fiber optic sensor for aqueous environment  

Science.gov (United States)

Fabrication and characterization of the surface plasmon resonance (SPR) based three channel fiber optic sensor for multiple parameter sensing have been carried out. Three probes have been prepared on a single fiber by coating silver, gold and copper along with one high index titanium oxide on three unclad well separated portions of the fiber respectively. SPR spectra have been recorded for aqueous sucrose solutions of varying refractive indices. The sensor relies on wavelength interrogation technique. To verify the results, simulations have been carried out using a multilayer model and geometrical optics. The experimental and simulated results have been found to match qualitatively. The present sensor can simultaneously sense multiple parameters/analytes at a single platform.

Verma, Roli; Gupta, Banshi D.

2014-03-01

387

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

388

Fiber Optic High Voltage Probe  

Energy Technology Data Exchange (ETDEWEB)

We developed a fiber coupled sensor to measure High Voltage directly using only light as the probe. We use the Pockles effect in lithium niobate crystal which will induce a phase shift in a laser beam that varies according to applied voltage. This can then be transformed into a modulation of beam intensity by polarizers, interferometery, or waveguide coupling. No voltage dividers are necessary, nor is any physical connection. This is accompanied by taking advantage of the structure of the power system itself, using voltage planes and dielectric insulation already present as the capacitive voltage divider. We hypothesize a bandwidth from GHz to DC. Such a system could be used in any application that calls for isolated and unobtrusive voltage sensing.

Matthew J. Heino

1999-08-01

389

An optical fiber optofluidic particle aspirator  

Science.gov (United States)

A fiberized optofluidic particle trapping device based on a micro-slot fabricated in a standard single-mode optical fiber by femtosecond laser micromachining is demonstrated. While fluidic convective motions move a large number of microparticles into the slot, the optical mode propagating in the nearby optical fiber core is exploited to trap and propel the particles inside the slot, thereby facilitating their collection at one of the slot extremities. The combined effect of fluidic and optical trapping allows for the collection of particles from as far as 60 ?m away from the optical trap. Application to particle and live cell trapping and propulsion is demonstrated.

Murugan, Ganapathy S.; Belal, Mohammad; Grivas, Christos; Ding, Ming; Wilkinson, James S.; Brambilla, Gilberto

2014-09-01

390

Laboratory Equipment Type Fiber Optic Refractometer  

Directory of Open Access Journals (Sweden)

Full Text Available Using fiber optics and micro optics technologies we designed aninnovative fiber optic index of refraction transducer that has uniqueproperties. On the base of this transducer a laboratory equipment typefiber optic refractometer was developed for liquid index of refractionmeasurements. Such refractometer may be used for medical,pharmaceutical, industrial fluid, petrochemical, plastic, food, andbeverage industry applications. For example, it may be used formeasuring the concentrations of aqueous solutions: as the concentrationor density of a solute increase, the refractive index increasesproportionately. The paper describes development work related to designof laboratory type fiber optic refractometer and describes experimentsto evaluation of its basic properties.

E. F. Carome

2002-09-01

391

Tunable Laser Development for In-flight Fiber Optic Based Structural Health Monitoring Systems  

Science.gov (United States)

The objective of this task is to investigate, develop, and demonstrate a low-cost swept lasing light source for NASA DFRC's fiber optics sensing system (FOSS) to perform structural health monitoring on current and future aerospace vehicles. This is the regular update of the Tunable Laser Development for In-flight Fiber Optic Based Structural Health Monitoring Systems website.

Richards, Lance; Parker, Allen; Chan, Patrick

2014-01-01

392

Optical pulse generation using fiber lasers and integrated optics  

International Nuclear Information System (INIS)

We have demonstrated an optical pulse forming system using fiber and integrated optics, and have designed a multiple-output system for a proposed fusion laser facility. Our approach is an advancement over previous designs for fusion lasers, and an unusual application of fiber lasers and integrated optics

393

A fiber optics textile composite sensor for geotechnical applications  

Science.gov (United States)

The fiber optics in structural health monitoring systems for civil engineering applications have been widely used. By integrating fiber optic sensing into a geotextile fabric, the TenCate GeoDetect® system is the first designed specifically for geotechnical applications. This monitoring solution embodies fiber optics on a geotextile fabric, e.g. a textile used into the soil, and combines the benefits of geotextile materials, such as high interface friction in contact with the soil, with the latest fiber optics sensing technologies. It aims to monitor geotechnical structure and to generate early warnings if it detects and localizes the early signs of malfunctioning, such as leaks or instability. This is a customizable solution: Fiber Bragg gratings, Brillouin and Raman scattering can be built into this system. These technologies measure both strain and temperature changes in soil structures. It can provide a leak and deformation location within accuracies resp. 1 l/min/m and 0.02%. The TenCate GeoDetect® solution provides objective, highly precise, and timely in-situ performance information, allowing the design professional and owner to understand system performance in addition to providing alerts for negative "geo-events" (subsidence) and other potentially deleterious events.

Artières, Olivier; Dortland, Gerrit

2010-09-01

394

Method and apparatus for distributed sensing of volatiles using a long period fiber grating sensor with modulated plastic coating for environmental monitoring  

Science.gov (United States)

Optical time domain reflectometry caused by absorption of a volatile or analyte into the fiber optic cladding is used as an optical nose. The fiber optics (14) are covered with a gas permeable film (44) which is patterned to leave millimeter wide gas permeable notches (48a-48d). The notches contain a sensing polymer that responds to different gases by expanding or contracting.

Ponce, Adrian (Inventor); Kossakovski, Dmitri A. (Inventor); Bearman, Gregory H. (Inventor)

2010-01-01

395

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 cryogenic propellant tank fill levels from 2 to 98 percent. The proposed sensor uses a single 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