Performance Evaluation of Fiber Bragg Gratings at Elevated Temperatures

NASA Technical Reports Server (NTRS)

Juergens, Jeffrey; Adamovsky, Grigory; Floyd, Bertram

2004-01-01

The development of integrated fiber optic sensors for smart propulsion systems demands that the sensors be able to perform in extreme environments. In order to use fiber optic sensors effectively in an extreme environment one must have a thorough understanding of the sensor s limits and how it responds under various environmental conditions. The sensor evaluation currently involves examining the performance of fiber Bragg gratings at elevated temperatures. Fiber Bragg gratings (FBG) are periodic variations of the refractive index of an optical fiber. These periodic variations allow the FBG to act as an embedded optical filter passing the majority of light propagating through a fiber while reflecting back a narrow band of the incident light. The peak reflected wavelength of the FBG is known as the Bragg wavelength. Since the period and width of the refractive index variation in the fiber determines the wavelengths that are transmitted and reflected by the grating, any force acting on the fiber that alters the physical structure of the grating will change what wavelengths are transmitted and what wavelengths are reflected by the grating. Both thermal and mechanical forces acting on the grating will alter its physical characteristics allowing the FBG sensor to detect both temperature variations and physical stresses, strain, placed upon it. This ability to sense multiple physical forces makes the FBG a versatile sensor. This paper reports on test results of the performance of FBGs at elevated temperatures. The gratings looked at thus far have been either embedded in polymer matrix materials or freestanding with the primary focus of this paper being on the freestanding FBGs. Throughout the evaluation process, various parameters of the FBGs performance were monitored and recorded. These parameters include the peak Bragg wavelength, the power of the Bragg wavelength, and total power returned by the FBG. Several test samples were subjected to identical test conditions to allow for statistical analysis of the data. Test procedures, calibrations, and referencing techniques are presented in the paper along with directions for future research.

Fiber optic plantar pressure/shear sensor

NASA Astrophysics Data System (ADS)

Soetanto, William; Nguyen, Ngoc T.; Wang, Wei-Chih

2011-04-01

A full-scale foot pressure/shear sensor that has been developed to help diagnose the cause of ulcer formation in diabetic patients is presented. The design involves a tactile sensor array using intersecting optical fibers embedded in soft elastomer. The basic configuration incorporates a mesh that is comprised of two sets of parallel optical fiber plane; the planes are configured so the parallel rows of fiber of the top and bottom planes are perpendicular to each other. Threedimensional information is determined by measuring the loss of light from each of the waveguide to map the overall pressure distribution and the shifting of the layers relative to each other. In this paper we will present the latest development on the fiber optic plantar pressure/shear sensor which can measure normal force up from 19.09 kPa to 1000 kPa.

A temperature-compensated optical fiber force sensor for minimally invasive surgeries

NASA Astrophysics Data System (ADS)

Mo, Z.; Xu, W.; Broderick, N.; Chen, H.

2015-12-01

Force sensing in minimally invasive surgery (MIS) is a chronic problem since it has an intensive magnetic resonance (MR) operation environment, which causes a high influence to traditional electronic force sensors. Optical sensor is a promising choice in this area because it is immune to MR influence. However, the changing temperature introduces a lot of noise signals to them, which is the main obstacle for optical sensing applications in MIS. This paper proposes a miniature temperature-compensated optical force sensor by using Fabry-Perot interference (FPI) principle. It can be integrated into medical tools' tips and the temperature noise is decreased by using a reference FPI temperature sensor. An injection needle with embedded temperature-compensated FPI force sensor has been fabricated and tested. And the comparison between temperature-force simulation results and the temperature-force experiment results has been carried out.

Transverse strain measurements using fiber optic grating based sensors

NASA Technical Reports Server (NTRS)

Udd, Eric (Inventor)

1998-01-01

A system and method to sense the application of transverse stress to an optical fiber which includes a light source that producing a relatively wide spectrum light beam. The light beam is reflected or transmitted off of an optical grating in the core of an optical fiber that is transversely stressed either directly or by the exposure to pressure when the fiber is bifringent so that the optical fiber responds to the pressure to transversely stress its core. When transversely stressed, the optical grating produces a reflection or transmission from the light beam that has two peaks or minimums in its frequency spectrum whose spacing and/or spread are indicative of the forces applied to the fiber. One or more detectors sense the reflection or transmissions from the optical grating to produce an output representative of the applied force. Multiple optical gratings and detectors may be employed to simultaneously measure temperature or the forces at different locations along the fiber.

Cartilage microindentation using cylindrical and spherical optical fiber indenters with integrated Bragg gratings as force sensors

NASA Astrophysics Data System (ADS)

Marchi, G.; Canti, O.; Baier, V.; Micallef, W.; Hartmann, B.; Alberton, P.; Aszodi, A.; Clausen-Schaumann, H.; Roths, J.

2018-02-01

Fiber optic microindentation sensors that have the potential to be integrated into arthroscopic instruments and to allow localizing degraded articular cartilage are presented in this paper. The indenters consist of optical fibers with integrated Bragg gratings as force sensors. In a basic configuration, the tip of the fiber optic indenter consists of a cleaved fiber end, forming a cylindrical flat punch indenter geometry. When using this indenter geometry, high stresses at the edges of the cylinder are present, which can disrupt the tissue structure. This is avoided with an improved version of the indenter. A spherical indenter tip that is formed by melting the end of the glass fiber. The spherical fiber tip shows the additional advantage of strongly reducing reflections from the fiber end. This allows a reduction of the length of the fiber optic sensor element from 65 mm of the flat punch type to 27 mm of the spherical punch. In order to compare the performance of both indenter types, in vitro stress-relaxation indentation experiments were performed on bovine articular cartilage with both indenter types, to assess biomechanical properties of bovine articular cartilage. For indentation depths between 60 μm and 300 μm, the measurements with both indenter types agreed very well with each other. This shows that both indenter geometries are suitable for microindentation measuremnts . The spherical indenter however has the additional advantage that it minimizes the risk to damage the surface of the tissue and has less than half dimensions than the flat indenter.

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

NASA Technical Reports Server (NTRS)

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

1991-01-01

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

Highly sensitive force sensor based on balloon-like interferometer

NASA Astrophysics Data System (ADS)

Wu, Yue; Xiao, Shiying; Xu, Yao; Shen, Ya; Jiang, Youchao; Jin, Wenxing; Yang, Yuguang; Jian, Shuisheng

2018-07-01

An all-fiber highly sensitive force sensor based on modal interferometer has been presented and demonstrated. The single-mode fiber (SMF) with coating stripped is designed into a balloon-like shape to form a modal interferometer. Due to the bent SMF, the interference occurs between the core mode and cladding modes. With variation of the force applied to the balloon-like interferometer, the bending diameter changes, which caused the wavelength shift of the modal interference. Thus the measurement of the force variation can be achieved by monitoring the wavelength shift. The performances of the interferometer with different bending diameter are experimentally investigated, and the maximum force sensitivity of 24.9 pm/ μ N can be achieved with the bending diameter 14 mm ranging from 0 μ N to 1464.12 μ N. Furthermore, the proposed fiber sensor exhibits the advantages of easy fabrication and low cost, making it a suitable candidate in the optical fiber sensing field.

Chemical, biochemical, and environmental fiber sensors III; Proceedings of the Meeting, Boston, MA, Sept. 4, 5, 1991

NASA Astrophysics Data System (ADS)

Lieberman, Robert A.

Various papers on chemical, biochemical, and environmental fiber sensors are presented. Individual topics addressed include: fiber optic pressure sensor for combustion monitoring and control, viologen-based fiber optic oxygen sensors, renewable-reagent fiber optic sensor for ocean pCO2, transition metal complexes as indicators for a fiber optic oxygen sensor, fiber optic pH measurements using azo indicators, simple reversible fiber optic chemical sensors using solvatochromic dyes, totally integrated optical measuring sensors, integrated optic biosensor for environmental monitoring, radiation dosimetry using planar waveguide sensors, optical and piezoelectric analysis of polymer films for chemical sensor characterization, source polarization effects in an optical fiber fluorosensor, lens-type refractometer for on-line chemical analysis, fiber optic hydrocarbon sensor system, chemical sensors for environmental monitoring, optical fibers for liquid-crystal sensing and logic devices, suitability of single-mode fluoride fibers for evanescent-wave sensing, integrated modules for fiber optic sensors, optoelectronic sensors based on narrowband A3B5 alloys, fiber Bragg grating chemical sensor.

Recent progress on mid-IR sensing with optical fibers

NASA Astrophysics Data System (ADS)

Kellner, Robert A.; Gobel, R.; Goetz, R.; Lendl, B.; Edl-Mizaikoff, B.; Tacke, Maurus; Katzir, Abraham

1995-09-01

Chemical sensors are analytical systems for the evaluation of compound- or ion-specific or - selective signals produced by specific or selective chemical reactions taking place at the interface between the chemically modified sensor surface and the substrate. The well known electrochemical sensing schemes have greatly contributed that sensors are considered now as the 'third supporting pillar of analytical chemistry' besides chromatography and spectroscopy. The aim of this paper is to describe the novel capabilities of chemical modified IR-transparent fibers as chemical IR-sensors for the on-line analysis of chlorinated hydrocarbons and organic compounds in aqueous solutions and gaseous mixtures, glucose, and sucrose in aqueous solution as developed in our laboratory. Moreover, the relative merits of this new method wil be depicted in comparison to other sensing techniques. Optical fiber sensors are novel analysis systems, based on molecular spectroscopy in the UV/VIS/IR-range. They benefit from the tremendous development in the field of optical fibers, an offspring of the telecommunication industry and the electronic revolution during the last few years. With the development of new materials besides the well known quartz fibers for the UV/VIS/NIR-range the optical window for fiber optic sensors was enlarged from 0,2 to 20 micrometers recently. The fiber length was increased recently to up to 2 meters for silver halides and approximately 10 meters for chalcogenides. New applications for environmental, food, and clinical sensing as well as process analysis are the driving force for modern research in IR-optical fiber sensors using mainly sapphire (Al2O3), chalcogenide (As-Se-Te) and silver halide (AgBr/AgCl) fibers and flow injection analysis (FIA) systems. Few representative examples for each of the various optical sensor types will be presented. Particular attention will be given to the use of silver halide fibers for the simultaneous determination of traces of chlorinated hydrocarbons in water and to FIA-systems for the process analysis of beverages.

Advanced Fiber-optic Monitoring System for Space-flight Applications

NASA Technical Reports Server (NTRS)

Hull, M. S.; VanTassell, R. L.; Pennington, C. D.; Roman, M.

2005-01-01

Researchers at Luna Innovations Inc. and the National Aeronautic and Space Administration s Marshall Space Flight Center (NASA MSFC) have developed an integrated fiber-optic sensor system for real-time monitoring of chemical contaminants and whole-cell bacterial pathogens in water. The system integrates interferometric and evanescent-wave optical fiber-based sensing methodologies with atomic force microscopy (AFM) and long-period grating (LPG) technology to provide versatile measurement capability for both micro- and nano-scale analytes. Sensors can be multiplexed in an array format and embedded in a totally self-contained laboratory card for use with an automated microfluidics platform.

Angle of Arrival Detection Through Artificial Neural Network Analysis of Optical Fiber Intensity Patterns

DTIC Science & Technology

1990-12-01

ARTIFICIAL NEURAL NETWORK ANALYSIS OF OPTICAL FIBER INTENSITY PATTERNS THESIS Scott Thomas Captain, USAF AFIT/GE/ENG/90D-62 DTIC...ELECTE ao • JAN08 1991 Approved for public release; distribution unlimited. AFIT/GE/ENG/90D-62 ANGLE OF ARRIVAL DETECTION THROUGH ARTIFICIAL NEURAL NETWORK ANALYSIS... ARTIFICIAL NEURAL NETWORK ANALYSIS OF OPTICAL FIBER INTENSITY PATTERNS L Introduction The optical sensors of United States Air Force reconnaissance

An Optical Actuation System and Curvature Sensor for a MR-compatible Active Needle

PubMed Central

Ryu, Seok Chang; Quek, Zhan Fan; Renaud, Pierre; Black, Richard J.; Daniel, Bruce L.; Cutkosky, Mark R.

2015-01-01

A side optical actuation method is presented for a slender MR-compatible active needle. The needle includes an active region with a shape memory alloy (SMA) wire actuator, where the wire generates a contraction force when optically heated by a laser delivered though optical fibers, producing needle tip bending. A prototype, with multiple side heating spots, demonstrates twice as fast an initial response compared to fiber tip heating when 0.8 W of optical power is applied. A single-ended optical sensor with a gold reflector is also presented to measure the curvature as a function of optical transmission loss. Preliminary tests with the sensor prototype demonstrate approximately linear response and a repeatable signal, independent of the bending history. PMID:26509099

Etched optical fiber vibration sensor to monitor health condition of beam like structures

NASA Astrophysics Data System (ADS)

Putha, Kishore; Dantala, Dinakar; Kamineni, Srimannarayana; Pachava, Vengal Rao

2013-06-01

Using a center etched single mode optical fiber, a simple vibration senor is designed to monitor the vibrations of a simply supported beam. The sensor has high linear response to the axial displacement of about 0.8 mm with a sensitivity of 32 mV/10 μm strain. The sensor is tested for periodic and suddenly released forces, and the results are found to coincide with the theoretical values. This simple design, small in size and low cost sensor may find applications in industry and civil engineering to monitor the vibrations of the beam structures and bridges.

Optical Fiber Demodulation System with High Performance for Assessing Fretting Damage of Steam Generator Tubes

PubMed Central

Huang, Peijian; Wang, Ning; Li, Junying; Zhu, Yong; Zhang, Jie; Xi, Zhide

2018-01-01

In order to access the fretting damage of the steam generator tube (SGT), a fast fiber Fabry-Perot (F-P) non-scanning correlation demodulation system based on a super luminescent light emitting diode (SLED) was performed. By demodulating the light signal coming out from the F-P force sensor, the radial collision force between the SGT and the tube support plate (TSP) was interrogated. For higher demodulation accuracy, the effects of the center wavelength, bandwidth, and spectrum noise of SLED were discussed in detail. Specially, a piezoelectric ceramic transducer (PZT) modulation method was developed to get rid of the interference of mode coupling induced by different types of fiber optics in the demodulation system. The reflectivity of optical wedge and F-P sensor was optimized. Finally, the demodulation system worked well in a 1:1 steam generator test loop and successfully demodulated a force signal of 32 N with a collision time of 2 ms. PMID:29329225

Optical Fiber Demodulation System with High Performance for Assessing Fretting Damage of Steam Generator Tubes.

PubMed

Huang, Peijian; Wang, Ning; Li, Junying; Zhu, Yong; Zhang, Jie; Xi, Zhide

2018-01-12

In order to access the fretting damage of the steam generator tube (SGT), a fast fiber Fabry-Perot (F-P) non-scanning correlation demodulation system based on a super luminescent light emitting diode (SLED) was performed. By demodulating the light signal coming out from the F-P force sensor, the radial collision force between the SGT and the tube support plate (TSP) was interrogated. For higher demodulation accuracy, the effects of the center wavelength, bandwidth, and spectrum noise of SLED were discussed in detail. Specially, a piezoelectric ceramic transducer (PZT) modulation method was developed to get rid of the interference of mode coupling induced by different types of fiber optics in the demodulation system. The reflectivity of optical wedge and F-P sensor was optimized. Finally, the demodulation system worked well in a 1:1 steam generator test loop and successfully demodulated a force signal of 32 N with a collision time of 2 ms.

Verification of the windings axial clamping forces for high voltage power transformers by using passively mode-locked fiber lasers

NASA Astrophysics Data System (ADS)

Şchiopu, IonuÅ£ Romeo; ǎgulinescu, Andrei, Dr; Iordǎnescu, Raluca; Marinescu, Andrei

2015-02-01

The current paper describes an optoelectronic method for direct monitoring of the axial clamping forces both in static and in dynamic duty. As advantages of this method we can state that it can be applied both to new and refurbished transformers without performing constructive changes or affecting in any way the transformer safety in operation. For monitoring the axial clamping forces for high-voltage (HV) power transformers, we use an optical fiber that we integrate into the laser cavity of a passively mode-locked fiber laser (PMFL). To each axial clamp corresponds a solitonic optical spectrum that is changed at the periodical passing of the fundamental soliton pulse through the sensitive fiber inside the transformer. Moreover, as a specific characteristic, the laser stability is unique for each set of axial clamping forces. Other important advantages of using an optical fiber as compared to the classical approach in which electronic sensors are used consist in the good reliability and insulator properties of the optical fiber, avoiding any risk of fire or damage of the transformer.

Fiber Optic Sensor System Using Birefringent Filters For Spectral Encoding

NASA Astrophysics Data System (ADS)

Dorsch, Friedhelm; Ulrich, Reinhard

1989-02-01

A system of multimode fiber optic sensors is described for the remote measurement of position, angle, force, pressure and other measurands that can be converted into a rotation of polarization. A birefringent filter encodes the polarization angle into the power ratio of two interleaved comb spectra or, in a modified implementation, into the absolute spectral position of a comb spectrum. By using identical filters in all transducers and in the evaluation unit, transducers for the same or different measurands become interchange-able. All sensors are of the incremental type, with accuracies reaching 0.5 % of one period of the measurand, independent of variations in the attenuation of the fiber link of up to 20dB.

Method of simultaneous measurement of two direction force and temperature using FBG sensor head.

PubMed

Kisała, Piotr; Cięszczyk, Sławomir

2015-04-01

This paper presents a method for measuring two components of bending force and temperature using one sensor head. Indirect inference based on the spectra of two fiber Bragg gratings (FBGs) placed on a cantilever beam is used. The method was developed during work on the inverse problem of determining a nonuniform stress distribution based on FBG spectra. A gradient in the FBG stress profile results in a characteristic shape of its reflective spectrum. The simultaneous measurements of force and temperature were possible through the use of an appropriate layout of the sensor head. The spectral characteristics of the sensor's gratings do not retain full symmetry, which is due to the geometry of the sensor's head and the related difference in the distribution of the axial stress of the gratings. In the proposed approach, the change in width of the sum of the normalized transmission spectra was used to determine the value of the applied force. In the presented method, an increase in the sensitivity of this change to the force is obtained relative to the other known systems. A change in the spectral width was observed for an increase in bending forces from 0 to 150 N. The sensitivity coefficient of the spectral width to force, defined as the ratio of the change of the spectral half-width to the change in force was 2.6e-3  nm/N for the first grating and 1.2e-3  nm/N for the second grating. However, the sensitivity of the whole sensor system was 5.8e-3  nm/N, which is greater than the sum of the sensitivities of the individual gratings. For the purpose of this work, a station with a thermal chamber has been designed with a bracket on which fiber optic transducers have been mounted for use in further measurements. The sensor head in this experiment is considered to be a universal device with potential applications in other types of optical sensors, and it can be treated as a module for development through its multiplication on a single optical fiber.

Fabrication of All-SiC Fiber-Optic Pressure Sensors for High-Temperature Applications

PubMed Central

Jiang, Yonggang; Li, Jian; Zhou, Zhiwen; Jiang, Xinggang; Zhang, Deyuan

2016-01-01

Single-crystal silicon carbide (SiC)-based pressure sensors can be used in harsh environments, as they exhibit stable mechanical and electrical properties at elevated temperatures. A fiber-optic pressure sensor with an all-SiC sensor head was fabricated and is herein proposed. SiC sensor diaphragms were fabricated via an ultrasonic vibration mill-grinding (UVMG) method, which resulted in a small grinding force and low surface roughness. The sensor head was formed by hermetically bonding two layers of SiC using a nickel diffusion bonding method. The pressure sensor illustrated a good linearity in the range of 0.1–0.9 MPa, with a resolution of 0.27% F.S. (full scale) at room temperature. PMID:27763494

Fabrication of All-SiC Fiber-Optic Pressure Sensors for High-Temperature Applications.

PubMed

Jiang, Yonggang; Li, Jian; Zhou, Zhiwen; Jiang, Xinggang; Zhang, Deyuan

2016-10-17

Single-crystal silicon carbide (SiC)-based pressure sensors can be used in harsh environments, as they exhibit stable mechanical and electrical properties at elevated temperatures. A fiber-optic pressure sensor with an all-SiC sensor head was fabricated and is herein proposed. SiC sensor diaphragms were fabricated via an ultrasonic vibration mill-grinding (UVMG) method, which resulted in a small grinding force and low surface roughness. The sensor head was formed by hermetically bonding two layers of SiC using a nickel diffusion bonding method. The pressure sensor illustrated a good linearity in the range of 0.1-0.9 MPa, with a resolution of 0.27% F.S. (full scale) at room temperature.

Fiber optic and laser sensors IV; Proceedings of the Meeting, Cambridge, MA, Sept. 22-24, 1986

NASA Technical Reports Server (NTRS)

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

1987-01-01

The conference presents papers on industrial uses of fiber optic sensors, point and distributed polarimetric optical fiber sensors, fiber optic electric field sensor technology, micromachined resonant structures, single-mode fibers for sensing applications, and measurement techniques for magnetic field gradient detection. Consideration is also given to electric field meter and temperature measurement techniques for the power industry, the calibration of high-temperature fiber-optic microbend pressure transducers, and interferometric sensors for dc measurands. Other topics include the recognition of colors and collision avoidance in robotics using optical fiber sensors, the loss compensation of intensity-modulating fiber-optic sensors, and an embedded optical fiber strain tensor for composite structure applications.

Fiber optic sensors

NASA Technical Reports Server (NTRS)

Hesse, J.; Sohler, W.

1984-01-01

A survey of the developments in the field of fiber optics sensor technology is presented along with a discussion of the advantages of optical measuring instruments as compared with electronic sensors. The two primary types of fiber optics sensors, specifically those with multiwave fibers and those with monowave fibers, are described. Examples of each major sensor type are presented and discussed. Multiwave detectors include external and internal fiber optics sensors. Among the monowave detectors are Mach-Zender interferometers, Michelson interferometers, Sagnac interferometers (optical gyroscopes), waveguide resonators, and polarimeter sensors. Integrated optical sensors and their application in spectroscopy are briefly discussed.

Fiber-optic bending sensor for cochlear implantation

NASA Astrophysics Data System (ADS)

Li, Enbang; Yao, Jianquan

2006-09-01

Cochlear implantation has been proved as a great success in treating profound sensorineural deafness in both children and adults. Cochlear electrode array implantation is a complex and delicate surgical process. Surgically induced damage to the inner wall of the scala tympani could happen if the insertion angle of the electrode is incorrect and an excessive insertion force is applied to the electrode. This damage could lead to severe degeneration of the remaining neural elements. It is therefore of vital importance to monitor the shape and position of the electrode during the implantation surgery. In this paper, we report a fiber-optic bending sensor which can be integrated with the electrode and used to guide the implantation process. The sensor consists of a piece of optical fiber. The end of the fiber is coated with aluminum layer to form a mirror. Bending the fiber with the electrode introduces loss to the light transmitting in the fiber. By detecting the power of the reflected light, we can detennine the bending happened to the fiber, and consequently measure the curved shape of the electrode. Experimental results show that the proposed fiber sensor is a promising technique to make in-situ monitoring of the shape and position of the electrode during the implantation process.

Fiber optic and laser sensors X; Proceedings of the Meeting, Boston, MA, Sept. 8-11, 1992

NASA Technical Reports Server (NTRS)

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

1993-01-01

Topics addressed include acoustic and pressure sensors; fiber optic gyros; electric and magnetic field sensors; bend, strain, and temperature sensors; industrial applications of sensors; and processing techniques. Particular attention is given to fiber optic interferometric acoustic sensors for wind tunnel applications, polished coupler and resonator fabrication, second-harmonic detection for rotation sensing in fiber optic gyros, simplified control theory in closed-loop fiber optic gyroscopes, and a Fabry-Perot sensor with digital signal processing for the measurement of magnetostriction. Also discussed are a Bragg fiber laser sensor, commercialization of fiber optic strain gauge systems, thermal ignition in hazardous environments due to stray light from optical fibers, a system for absolute measurements by interferometric sensors, and high-performance interferometric demodulation techniques.

Fiber optic sensors; Proceedings of the Meeting, Cannes, France, November 26, 27, 1985

NASA Technical Reports Server (NTRS)

Arditty, Herve J. (Editor); Jeunhomme, Luc B. (Editor)

1986-01-01

The conference presents papers on distributed sensors and sensor networks, signal processing and detection techniques, temperature measurements, chemical sensors, and the measurement of pressure, strain, and displacements. Particular attention is given to optical fiber distributed sensors and sensor networks, tactile sensing in robotics using an optical network and Z-plane techniques, and a spontaneous Raman temperature sensor. Other topics include coherence in optical fiber gyroscopes, a high bandwidth two-phase flow void fraction fiber optic sensor, and a fiber-optic dark-field microbend sensor.

Novel Fiber-Optic Ring Acoustic Emission Sensor

PubMed Central

Han, Xiaole; Xia, Dong; Liu, Taolin; Lang, Hao

2018-01-01

Acoustic emission technology has been applied to many fields for many years. However, the conventional piezoelectric acoustic emission sensors cannot be used in extreme environments, such as those with heavy electromagnetic interference, high pressure, or strong corrosion. In this paper, a novel fiber-optic ring acoustic emission sensor is proposed. The sensor exhibits high sensitivity, anti-electromagnetic interference, and corrosion resistance. First, the principle of a novel fiber-optic ring sensor is introduced. Different from piezoelectric and other fiber acoustic emission sensors, this novel sensor includes both a sensing skeleton and a sensing fiber. Second, a heterodyne interferometric demodulating method is presented. In addition, a fiber-optic ring sensor acoustic emission system is built based on this method. Finally, fiber-optic ring acoustic emission experiments are performed. The novel fiber-optic ring sensor is glued onto the surface of an aluminum plate. The 150 kHz standard continuous sinusoidal signals and broken lead signals are successfully detected by the novel fiber-optic ring acoustic emission sensor. In addition, comparison to the piezoelectric acoustic emission sensor is performed, which shows the availability and reliability of the novel fiber-optic ring acoustic emission sensor. In the future, this novel fiber-optic ring acoustic emission sensor will provide a new route to acoustic emission detection in harsh environments. PMID:29342858

Novel Fiber-Optic Ring Acoustic Emission Sensor.

PubMed

Wei, Peng; Han, Xiaole; Xia, Dong; Liu, Taolin; Lang, Hao

2018-01-13

Acoustic emission technology has been applied to many fields for many years. However, the conventional piezoelectric acoustic emission sensors cannot be used in extreme environments, such as those with heavy electromagnetic interference, high pressure, or strong corrosion. In this paper, a novel fiber-optic ring acoustic emission sensor is proposed. The sensor exhibits high sensitivity, anti-electromagnetic interference, and corrosion resistance. First, the principle of a novel fiber-optic ring sensor is introduced. Different from piezoelectric and other fiber acoustic emission sensors, this novel sensor includes both a sensing skeleton and a sensing fiber. Second, a heterodyne interferometric demodulating method is presented. In addition, a fiber-optic ring sensor acoustic emission system is built based on this method. Finally, fiber-optic ring acoustic emission experiments are performed. The novel fiber-optic ring sensor is glued onto the surface of an aluminum plate. The 150 kHz standard continuous sinusoidal signals and broken lead signals are successfully detected by the novel fiber-optic ring acoustic emission sensor. In addition, comparison to the piezoelectric acoustic emission sensor is performed, which shows the availability and reliability of the novel fiber-optic ring acoustic emission sensor. In the future, this novel fiber-optic ring acoustic emission sensor will provide a new route to acoustic emission detection in harsh environments.

Fiber optic sensor and method for making

DOEpatents

Vartuli, James Scott; Bousman, Kenneth Sherwood; Deng, Kung-Li; McEvoy, Kevin Paul; Xia, Hua

2010-05-18

A fiber optic sensor including a fiber having a modified surface integral with the fiber wherein the modified surface includes an open pore network with optical agents dispersed within the open pores of the open pore network. Methods for preparing the fiber optic sensor are also provided. The fiber optic sensors can withstand high temperatures and harsh environments.

Fiber optic temperature sensor

NASA Technical Reports Server (NTRS)

Sawatari, Takeo (Inventor); Gaubis, Philip A. (Inventor)

2000-01-01

A fiber optic temperature sensor uses a light source which transmits light through an optical fiber to a sensor head at the opposite end of the optical fiber from the light source. The sensor head has a housing coupled to the end of the optical fiber. A metallic reflective surface is coupled to the housing adjacent the end of the optical fiber to form a gap having a predetermined length between the reflective surface and the optical fiber. A detection system is also coupled to the optical fiber which determines the temperature at the sensor head from an interference pattern of light which is reflected from the reflective surface.

Fiber optic temperature sensor

NASA Technical Reports Server (NTRS)

Sawatari, Takeo (Inventor); Gaubis, Philip A. (Inventor); Mattes, Brenton L. (Inventor); Charnetski, Clark J. (Inventor)

1999-01-01

A fiber optic temperature sensor uses a light source which transmits light through an optical fiber to a sensor head at the opposite end of the optical fiber from the light source. The sensor head has a housing coupled to the end of the optical fiber. A metallic reflective surface is coupled to the housing adjacent the end of the optical fiber to form a gap having a predetermined length between the reflective surface and the optical fiber. A detection system is also coupled to the optical fiber which determines the temperature at the sensor head from an interference pattern of light which is reflected from the reflective surface.

Textile Pressure Sensor Made of Flexible Plastic Optical Fibers

PubMed Central

Rothmaier, Markus; Luong, Minh Phi; Clemens, Frank

2008-01-01

In this paper we report the successful development of pressure sensitive textile prototypes based on flexible optical fibers technology. Our approach is based on thermoplastic silicone fibers, which can be integrated into woven textiles. As soon as pressure at a certain area of the textile is applied to these fibers they change their cross section reversibly, due to their elastomeric character, and a simultaneous change in transmitted light intensity can be detected. We have successfully manufactured two different woven samples with fibers of 0.51 and 0.98 mm diameter in warp and weft direction, forming a pressure sensitive matrix. Determining their physical behavior when a force is applied shows that pressure measurements are feasible. Their usable working range is between 0 and 30 N. Small drifts in the range of 0.2 to 4.6%, over 25 load cycles, could be measured. Finally, a sensor array of 2 × 2 optical fibers was tested for sensitivity, spatial resolution and light coupling between fibers at intersections. PMID:27879938

A modular optical sensor

NASA Astrophysics Data System (ADS)

Conklin, John Albert

This dissertation presents the design of a modular, fiber-optic sensor and the results obtained from testing the modular sensor. The modular fiber-optic sensor is constructed in such manner that the sensor diaphragm can be replaced with different configurations to detect numerous physical phenomena. Additionally, different fiber-optic detection systems can be attached to the sensor. Initially, the modular sensor was developed to be used by university of students to investigate realistic optical sensors and detection systems to prepare for advance studies of micro-optical mechanical systems (MOMS). The design accomplishes this by doing two things. First, the design significantly lowers the costs associated with studying optical sensors by modularizing the sensor design. Second, the sensor broadens the number of physical phenomena that students can apply optical sensing techniques to in a fiber optics sensor course. The dissertation is divided into seven chapters covering the historical development of fiber-optic sensors, a theoretical overview of fiber-optic sensors, the design, fabrication, and the testing of the modular sensor developed in the course of this work. Chapter 1 discusses, in detail, how this dissertation is organized and states the purpose of the dissertation. Chapter 2 presents an historical overview of the development of optical fibers, optical pressure sensors, and fibers, optical pressure sensors, and optical microphones. Chapter 3 reviews the theory of multi-fiber optic detection systems, optical microphones, and pressure sensors. Chapter 4 presents the design details of the modular, optical sensor. Chapter 5 delves into how the modular sensor is fabricated and how the detection systems are constructed. Chapter 6 presents the data collected from the microphone and pressure sensor configurations of the modular sensor. Finally, Chapter 7 discusses the data collected and draws conclusions about the design based on the data collected. Chapter 7 also presents future work needed to expand the functionality and utility of the modular sensor.

Monitoring Composite Material Pressure Vessels with a Fiber-Optic/Microelectronic Sensor System

NASA Technical Reports Server (NTRS)

Klimcak, C.; Jaduszliwer, B.

1995-01-01

We discuss the concept of an integrated, fiber-optic/microelectronic distributed sensor system that can monitor composite material pressure vessels for Air Force space systems to provide assessments of the overall health and integrity of the vessel throughout its entire operating history from birth to end of life. The fiber optic component would include either a semiconductor light emitting diode or diode laser and a multiplexed fiber optic sensing network incorporating Bragg grating sensors capable of detecting internal temperature and strain. The microelectronic components include a power source, a pulsed laser driver, time domain data acquisition hardware, a microprocessor, a data storage device, and a communication interface. The sensing system would be incorporated within the composite during its manufacture. The microelectronic data acquisition and logging system would record the environmental conditions to which the vessel has been subjected to during its storage and transit, e.g., the history of thermal excursions, pressure loading data, the occurrence of mechanical impacts, the presence of changing internal strain due to aging, delamination, material decomposition, etc. Data would be maintained din non-volatile memory for subsequent readout through a microcomputer interface.

Initial Performance Evaluation of Optical Fibers and Sensors Under High-Energy Electron Beam Irradiation

NASA Astrophysics Data System (ADS)

Palmer, Matthew E.; Slusher, David; Fielder, Robert S.

2006-01-01

In this paper, recent work on the performance of optical fiber, fiber optic sensors, and fiber optic connectors under the influence of a high-energy electron beam is presented. Electron beam irradiation is relevant for the Jupiter Icy Moons Orbiter (JIMO) mission due to the high electron radiation environment surrounding Jupiter. As an initial feasibility test, selected optical fiber components were exposed to dose levels relevant to the Jupiter environment. Three separate fiber types were used: one series consisted of pure silica core fiber, two other series consisted of different levels of Germania-doped fiber. Additionally, a series of fused silica Extrinsic Fabry-Perot Interferometer (EFPI)-based fiber optic sensors and two different types of fiber optic connectors were tested. Two types of fiber coatings were evaluated: acrylate and polyimide. All samples were exposed to three different dose levels: 2 MRad, 20 MRad, and 50 MRad. Optical loss measurements were made on the optical fiber spools as a function of wavelength between 750 and 1750nm at periodic intervals up to 75 hrs after exposure. Attenuation is minimal and wavelength-dependent. Fiber optic sensors were evaluated using a standard EFPI sensor readout and diagnostic system. Optical connectors and optical fiber coatings were visually inspected for degradation. Additionally, tensile testing and minimum bend radius testing was conducted on the fibers. Initial loss measurements indicate a low-level of induced optical attenuation in the fiber which recovers with time. The fiber optic sensors exhibited no observable degradation after exposure. The optical fiber connectors and coatings also showed no observable degradation. In addition to harsh environment survivability, fiber optic sensors offer a number of intrinsic advantages for space nuclear power applications including extremely low mass, immunity to electromagnetic interference, self diagnostics / prognostics, and smart sensor capability. Deploying fiber optic sensors on future space exploration missions would provide a substantial improvement in spacecraft instrumentation.

The Fiber Grating Sensors Applied in the Deformation Measurement of Shipborne Antenna Basement

NASA Astrophysics Data System (ADS)

Liu, Yong; Chen, Jiahong; Zhao, Wenhua

2016-02-01

The optical fiber grating sensor is a novel fibre-optical passive device, its reflecting optical spectrum is linearly related with strain. It is broadly applied in the structural monitoring industry. Shipborne antenna basement is the basic supporting structure for the radar tracking movement. The bending deformation of the basement caused by ship attitude changing influences the antenna tracking precision, According to the structure of shipborne antenna basement, a distributed strain testing method based on the fibre grating sensor is approved to measure the bending deformation under the bending force. The strain-angle model is built. The regularity of the strain distribution is obtained. The finite element method is used to analyze the deformation of the antenna basement. The measuring experiment on the contractible basement mould is carried out to verify the availability of the method. The result of the experiment proves that the model is effective to apply in the deformation measurement. It provides an optimized method for the distribution of the fiber grating sensor in the actual measuring process.

Optical-Fiber Fluorosensors With Polarized Light Sources

NASA Technical Reports Server (NTRS)

Egalon, Claudio O.; Rogowski, Robert S.

1995-01-01

Chemiluminescent and/or fluorescent molecules in optical-fiber fluorosensors oriented with light-emitting dipoles along transverse axis. Sensor of proposed type captures greater fraction of chemiluminescence or fluorescence and transmits it to photodetector. Transverse polarization increases sensitivity. Basic principles of optical-fiber fluorosensors described in "Making Optical-Fiber Chemical Sensors More Sensitive" (LAR-14525), "Improved Optical-Fiber Chemical Sensors" (LAR-14607), and "Improved Optical-Fiber Temperature Sensors" (LAR-14647).

High pressure fiber optic sensor system

DOE Office of Scientific and Technical Information (OSTI.GOV)

Guida, Renato; Xia, Hua; Lee, Boon K

2013-11-26

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

International Instrumentation Symposium, 34th, Albuquerque, NM, May 2-6, 1988, Proceedings

NASA Astrophysics Data System (ADS)

Various papers on aerospace instrumentation are presented. The general topics addressed include: blast and shock, wind tunnel instrumentations and controls, digital/optical sensors, software design/development, special test facilities, fiber optic techniques, electro/fiber optical measurement systems, measurement uncertainty, real time systems, pressure. Also discussed are: flight test and avionics instrumentation, data acquisition techniques, computer applications, thermal force and displacement, science and government, modeling techniques, reentry vehicle testing, strain and pressure.

Micro-LiDAR velocity, temperature, density, concentration sensor

NASA Technical Reports Server (NTRS)

Dorrington, Adrian A. (Inventor); Danehy, Paul M. (Inventor)

2010-01-01

A light scatter sensor includes a sensor body in which are positioned a plurality of optical fibers. The sensor body includes a surface, in one end of each of the optical fibers terminates at the surface of the sensor body. One of the optical fibers is an illumination fiber for emitting light. A plurality of second optical fibers are collection fibers for collecting scattered light signals. A light sensor processor is connected to the collection fibers to detect the scattered light signals.

EC91-436-8

NASA Image and Video Library

1991-08-16

The National Aeronautics and Space Administration's Systems Research Aircraft (SRA), a highly modified F-18 jet fighter, during a research flight. The former Navy aircraft was flown by NASA's Dryden Flight Research Center at Edwards Air Force Base, California, to evaluate a number of experimental aerospace technologies in a multi-year, joint NASA/DOD/industry program. Among the more than 20 experiments flight-tested were several involving fiber optic sensor systems. Experiments developed by McDonnell-Douglas and Lockheed-Martin centered on installation and maintenace techniques for various types of fiber-optic hardware proposed for use in military and commercial aircraft, while a Parker-Hannifin experiment focused in alternative fiber-optic designs for position measurement sensors as well as operational experience in handling optical sensor systems. Other experiments flown on this testbed aircraft included electronically-controlled control surface actuators, flush air data collection systems, "smart" skin antennae and laser-based systems. Incorporation of one or more of these technologies in future aircraft and spacecraft could result in signifigant savings in weight, maintenance and overall cost.

Structural Health Monitoring Using Textile Reinforcement Structures with Integrated Optical Fiber Sensors

PubMed Central

Bremer, Kort; Weigand, Frank; Zheng, Yulong; Alwis, Lourdes Shanika; Helbig, Reinhard; Roth, Bernhard

2017-01-01

Optical fiber-based sensors “embedded” in functionalized carbon structures (FCSs) and textile net structures (TNSs) based on alkaline-resistant glass are introduced for the purpose of structural health monitoring (SHM) of concrete-based structures. The design aims to monitor common SHM parameters such as strain and cracks while at the same time acting as a structural strengthening mechanism. The sensor performances of the two systems are characterized in situ using Mach-Zehnder interferometric (MZI) and optical attenuation measurement techniques, respectively. For this purpose, different FCS samples were subjected to varying elongation using a tensile testing machine by carefully incrementing the applied force, and good correlation between the applied force and measured length change was observed. For crack detection, the functionalized TNSs were embedded into a concrete block which was then exposed to varying load using the three-point flexural test until destruction. Promising results were observed, identifying that the location of the crack can be determined using the conventional optical time domain reflectometry (OTDR) technique. The embedded sensors thus evaluated show the value of the dual achievement of the schemes proposed in obtaining strain/crack measurement while being utilized as strengthening agents as well. PMID:28208636

A new fiber optic sensor for inner surface roughness measurement

NASA Astrophysics Data System (ADS)

Xu, Xiaomei; Liu, Shoubin; Hu, Hong

2009-11-01

In order to measure inner surface roughness of small holes nondestructively, a new fiber optic sensor is researched and developed. Firstly, a new model for surface roughness measurement is proposed, which is based on intensity-modulated fiber optic sensors and scattering modeling of rough surfaces. Secondly, a fiber optical measurement system is designed and set up. Under the help of new techniques, the fiber optic sensor can be miniaturized. Furthermore, the use of micro prism makes the light turn 90 degree, so the inner side surface roughness of small holes can be measured. Thirdly, the fiber optic sensor is gauged by standard surface roughness specimens, and a series of measurement experiments have been done. The measurement results are compared with those obtained by TR220 Surface Roughness Instrument and Form Talysurf Laser 635, and validity of the developed fiber optic sensor is verified. Finally, precision and influence factors of the fiber optic sensor are analyzed.

Metal-Coated Optical Fibers for High Temperature Applications

NASA Technical Reports Server (NTRS)

Zeakes, Jason; Murphy, Kent; Claus, Richard; Greene, Jonathan; Tran, Tuan

1996-01-01

This poster will highlight on-going research at the Virginia Tech Fiber & Electro-Optics Research Center (FEORC) in the area of thin films on optical fibers. Topics will include the sputter deposition of metals and metal; alloys onto optical fiber and fiber optic sensors for innovative applications. Specific information will be available on thin film fiber optic hydrogen sensors, corrosion sensors, and metal-coated optical fiber for high temperature aerospace applications.

Optical Fiber-Based MR-Compatible Sensors for Medical Applications: An Overview

PubMed Central

Taffoni, Fabrizio; Formica, Domenico; Saccomandi, Paola; Di Pino, Giovanni; Schena, Emiliano

2013-01-01

During last decades, Magnetic Resonance (MR)—compatible sensors based on different techniques have been developed due to growing demand for application in medicine. There are several technological solutions to design MR-compatible sensors, among them, the one based on optical fibers presents several attractive features. The high elasticity and small size allow designing miniaturized fiber optic sensors (FOS) with metrological characteristics (e.g., accuracy, sensitivity, zero drift, and frequency response) adequate for most common medical applications; the immunity from electromagnetic interference and the absence of electrical connection to the patient make FOS suitable to be used in high electromagnetic field and intrinsically safer than conventional technologies. These two features further heightened the potential role of FOS in medicine making them especially attractive for application in MRI. This paper provides an overview of MR-compatible FOS, focusing on the sensors employed for measuring physical parameters in medicine (i.e., temperature, force, torque, strain, and position). The working principles of the most promising FOS are reviewed in terms of their relevant advantages and disadvantages, together with their applications in medicine. PMID:24145918

Modulated-splitting-ratio fiber-optic temperature sensor

NASA Technical Reports Server (NTRS)

Beheim, Glenn; Anthan, Donald J.; Rys, John R.; Fritsch, Klaus; Ruppe, Walter A.

1988-01-01

A fiber-optic temperature sensor is described, which uses a small silicon beamsplitter whose splitting ratio varies as a function of temperature. A four-beam technique is used to measure the sensor's temperature-indicating splitting ratio. This referencing method provides a measurement that is largely independent of the transmission properties of the sensor's optical fiber link. A significant advantage of this sensor, relative to other fiber-optic sensors, is its high stability, which permits the fiber-optic components to be readily substituted, thereby simplifying the sensor's installation and maintenance.

Escherichia coli Fiber Sensors Using Concentrated Dielectrophoretic Force with Optical Defocusing Method.

PubMed

Tai, Yi-Hsin; Lee, Chia-Wei; Chang, Dao-Ming; Lai, Yu-Sheng; Huang, Ding-Wei; Wei, Pei-Kuen

2018-05-25

A sensitive tapered optical fiber tip combined with dielectrophoretic (DEP) trapping was used for rapid and label-free detection of bacteria in water. The angular spectrum of the optical field at the fiber tip was changed with the surrounding refractive index (RI). By measuring far-field intensity change at the defocus plane, the intensity sensitivity was up to 95 200%/RIU (RI unit), and the detection limit was 5.2 × 10 -6 RIU at 0.5% intensity stability. By applying an AC voltage to a Ti/Al coated fiber tip and an indium-tin-oxide glass, the DEP force effectively trapped the Escherichia coli ( E. coli) near the fiber tip. Those bacteria can be directly measured from optical intensity change due to the increase of surrounding RI. By immobilizing the antibody on the Ti/Al fiber tip, the tests for specific K12 bacteria and nonspecific BL21 bacteria verified the specificity. The antibody-immobilized Ti/Al coated fiber tip with DEP trapping can detect bacteria at a concentration about 100 CFU/mL.

Preliminary design of land displacement-optical fiber sensor and analysis of observation during laboratory and field test

NASA Astrophysics Data System (ADS)

Bayuwati, Dwi; Waluyo, Tomi B.; Widiyatmoko, Bambang

2015-01-01

An optical fiber optic sensor for detecting land displacement is discussed in this paper. The sensor system consists of a laser at wavelength 1.3 um, optical fiber coupler, optical fiber as sensor and light transmitting media, PIN photodiodedetector system, data logger and personal computer. Sensor was made from a curved optical fiber with diameter 35 mm, which will be changed into a heart-shape fiber if it is pulled. The heart-shape fiber sensor is the modification of the earlier displacement fiber sensor model which was in an ellipse form. Light to and from the optical fiber sensor was transmitted into a length of a multi core, single mode optical fiber cable. The scheme of the optical displacement sensor system has been described here. Characterization in the laboratory has been done by applying a series of pulling mechanism, on the heart-shape fiber sensor; which represents the land displacement process. Characterization in the field was carried out by mounting the sensor system on a scaled-down model of a land slope and artificially reproducing the landslide process using a steady-flow of artificial rainfall as the trigger. The voltage sensor output was recorded during the artificial landslide process. The displacement occurence can be indicated from the declining of the sensor signal received by the detector while the reference signal is steady. Characterization in the laboratory resulted in the performance of the optical fiber land displacement, namely, sensitivity 0.027(mV/mV)/mm, resolution 0.37 mm and measurement range 30 mm; compared with earlier optical fiber sensor performance with similar sensitivity and resolution which works only in 8 mm displacement range. Based on the experiment of landslides simulation in the field, we can define a critical condition in the real situation before landslides occurence to take any measures to prevent more casualties and losses.

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

PubMed Central

Wang, Chuji

2009-01-01

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. PMID:22408471

Detection of Internal Metal Loss in Steel Pipes and Storage Tanks via Magnetic-Based Fiber Optic Sensor

PubMed Central

Almahmoud, Safieh; Vahdati, Nader; Rostron, Paul

2018-01-01

A monitoring solution was developed for detection of material loss in metals such as carbon steel using the force generated by permanent magnets in addition to the optical strain sensing technology. The working principle of the sensing system is related to the change in thickness of a steel plate, which typically occurs due to corrosion. As thickness decreases, the magnetostatic force between the magnet and the steel structure also decreases. This, in turn, affects the strain measured using the optical fiber. The sensor prototype was designed and built after verifying its sensitivity using a numerical model. The prototype was tested on steel plates of different thicknesses to establish the relationship between the metal thickness and measured strain. The results of experiments and numerical models demonstrate a strong relationship between the metal thickness and the measured strain values. PMID:29518006

Fingertip-shaped optical tactile sensor for robotic applications

NASA Technical Reports Server (NTRS)

Begej, Stefan

1988-01-01

Progress is described regarding the development of a high-density, fiber-optic, fingertip-shaped tactile sensor specifically designed for application to dexterous robotics. The sensor operates on optical principles involving the frustration of total internal reflection at a waveguide/elastomer interface and generates a grey-scale tactile image that represents the normal forces of contact. The sensor contains 256 taxels (sensing sites) distributed in a dual-density pattern that includes a tactile fovea near the tip which measures 13 mm x 13 mm and contains 169 taxels. The details regarding the design and construction of this tactile sensor are presented, in addition to photographs of tactile imprints.

Fiber optic vibration sensor

DOEpatents

Dooley, Joseph B.; Muhs, Jeffrey D.; Tobin, Kenneth W.

1995-01-01

A fiber optic vibration sensor utilizes two single mode optical fibers supported by a housing with one optical fiber fixedly secured to the housing and providing a reference signal and the other optical fiber having a free span length subject to vibrational displacement thereof with respect to the housing and the first optical fiber for providing a signal indicative of a measurement of any perturbation of the sensor. Damping or tailoring of the sensor to be responsive to selected levels of perturbation is provided by altering the diameter of optical fibers or by immersing at least a portion of the free span length of the vibration sensing optical fiber into a liquid of a selected viscosity.

Fiber optic vibration sensor

DOEpatents

Dooley, J.B.; Muhs, J.D.; Tobin, K.W.

1995-01-10

A fiber optic vibration sensor utilizes two single mode optical fibers supported by a housing with one optical fiber fixedly secured to the housing and providing a reference signal and the other optical fiber having a free span length subject to vibrational displacement thereof with respect to the housing and the first optical fiber for providing a signal indicative of a measurement of any perturbation of the sensor. Damping or tailoring of the sensor to be responsive to selected levels of perturbation is provided by altering the diameter of optical fibers or by immersing at least a portion of the free span length of the vibration sensing optical fiber into a liquid of a selected viscosity. 2 figures.

Fabrication of micro/nano optical fiber by mechano-electrospinning

NASA Astrophysics Data System (ADS)

Chen, Qinnan; Wu, Dezhi; Yu, Zhe; Mei, Xuecui; Fang, Ke; Sun, Daoheng

2017-10-01

We study a novel fabrication method of micro/nano optical fiber by mechano-electrospinning (MES) direct-written technology. MES process is able to precisely manipulate the position and diameter of the electro-spun micro/nano fiber by adjusting the mechanical drawing force, which through changing the speed of motion stage (substrate). By adjusting the substrate speed, the nozzle-to-substrate distance and the applied voltage, the poly(methyl methacrylate) (PMMA) micro/nano optical fibers (MNOF) with controlled diameter are obtained and the tapered MNOF are fabricated by continuously changing the substrate speed. The transmission characteristics of PMMA micro/nano fiber is experimentally demonstrated, and a PMMA micro/nano fiber based refractive index sensor is designed. Our works shows the new fabrication method of MNOF by MES has the potential in the field of light mode conversion, optical waveguide coupling, refractive index detection and new micro/nano optical fiber components.

Nanometer-scale displacement measurement with high resolution using dual cavity Fabry-Pérot interferometer for biomimetic robots.

PubMed

Lee, Jin-Hyuk; Kim, Dae-Hyun

2014-10-01

A sensor of a biomimetic robot has to measure very small environmental changes such as, nanometer scale strains or displacements. Fiber optic sensor can be also one of candidates for the biomimetic sensor because the sensor is like thread and the shape of the sensor is similar to muscle fiber. A fiber optic interferometer, which is an optical-based sensor, can measure displacement precisely, so such device has been widely studied for the measurement of displacement on a nanometer-scale. Especially, a Quadrature Phase-Shifted Fiber Fabry-Pérot interferometer (QPS-FFPI) uses phase-information for this measurement, allowing it to provide a precision result with high resolution. In theory, the QPS-FFPI generates two sinusoidal signals of which the phase difference should be 90 degrees for the exact measurement of the displacement. In order to guarantee the condition of the phase difference, the relative adjustment of the cavities of the optical fibers is required. However, with such precise adjustment it is very hard to fix the proper difference of the two cavities for quadrature-phase-shifting. In this paper, a dual-cavity FFPI is newly proposed to measure the displacement on a nanometer-scale with a specific type of signal processing. In the signal processing, a novel phase-compensation algorithm is applied to force the phase difference to be exactly 90 degrees without any physical adjustment. As a result, the paper shows that the phase-compensated dual-cavity FFPI can effectively measure nanometer-scale displacement with high resolution under dynamic conditions.

Fiber optic sensors for corrosion detection

NASA Technical Reports Server (NTRS)

Smith, Alphonso C.

1993-01-01

The development of fiber optic sensors for the detection of a variety of material parameters has grown tremendously over the past several years. Additionally, the potential for analytical applications of fiber optic sensors have become more widely used. New pH sensors have also been developed using fiber optic techniques to detect fluorescence characteristics from immobilized fluorogenic reagent chemicals. The primary purpose of this research was to investigate the feasibility of using fiber optic sensors to detect the presence of Al(sup 3+) ions made in the process of environmental corrosion of aluminum materials. The Al(sup 3+) ions plus a variety of other type of metal ions can be detected using analytical techniques along with fiber optic sensors.

Development of a disposable force-sensing glove for clinicians and demonstration of its force measurements on patients during rehabilitation following anterior cruciate ligament reconstruction surgery

NASA Astrophysics Data System (ADS)

Wang, Wei-Chih; Linders, David R.; Nuckley, David J.

2017-12-01

For many clinicians, their effectiveness is dependent on the magnitude of forces they manually apply to their patients. However, current state-of-the-art care strategies lack quantitative feedback, making it difficult to provide consistent care over time and among multiple clinicians. To provide real-time quantitative feedback to clinicians, we have developed a disposable glove with a force sensor embedded in the fingertips or palm. The sensor is based on the fiber-optic bendloss effect whereby light intensity from an infrared source is attenuated as the fiber is bent between a series of corrugated teeth. The sensor fabricated has a very low profile (10×7×1 mm) and has demonstrated high sensitivity, accuracy, range, and durability. Force feedback up to 90 N with an average force threshold at 0.19 N and average sensor resolution at 0.05 N has been demonstrated. A preliminary clinical study has also been conducted with anterior cruciate ligament reconstruction patients who show significant range of motion improvement when treated with the force-sensing glove.

An Optical Fiber Viscometer Based on Long-Period Fiber Grating Technology and Capillary Tube Mechanism

PubMed Central

Wang, Jian-Neng; Tang, Jaw-Luen

2010-01-01

This work addresses the development and assessment of a fiber optical viscometer using a simple and low-cost long-period fiber grating (LPFG) level sensor and a capillary tube mechanism. Previous studies of optical viscosity sensors were conducted by using different optical sensing methods. The proposed optical viscometer consists of an LPFG sensor, a temperature-controlled chamber, and a cone-shaped reservoir where gravitational force could cause fluid to flow through the capillary tube. We focused on the use of LPFGs as level sensors and the wavelength shifts were not used to quantify the viscosity values of asphalt binders. When the LPFG sensor was immersed in the constant volume (100 mL) AC-20 asphalt binder, a wavelength shift was observed and acquired using LabVIEW software and GPIB controller. The time spent between empty and 100 mL was calculated to determine the discharge time. We simultaneously measured the LPFG-induced discharge time and the transmission spectra both in hot air and AC-20 asphalt binder at five different temperatures, 60, 80, 100, 135, and 170 Celsius. An electromechanical rotational viscometer was also used to measure the viscosities, 0.15–213.80 Pa·s, of the same asphalt binder at the above five temperatures. A non-linear regression analysis was performed to convert LPFG-induced discharge time into viscosities. Comparative analysis shows that the LPFG-induced discharge time agreed well with the viscosities obtained from the rotational viscometer. PMID:22163519

Overview of Fiber-Optical Sensors

NASA Technical Reports Server (NTRS)

Depaula, Ramon P.; Moore, Emery L.

1987-01-01

Design, development, and sensitivity of sensors using fiber optics reviewed. State-of-the-art and probable future developments of sensors using fiber optics described in report including references to work in field. Serves to update previously published surveys. Systems incorporating fiber-optic sensors used in medical diagnosis, navigation, robotics, sonar, power industry, and industrial controls.

78 FR 17187 - Notice of Intent To Grant Exclusive Patent License; Fiber Optic Sensor Systems Technology...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-03-20

...; Fiber Optic Sensor Systems Technology Corporation AGENCY: Department of the Navy, DoD. ACTION: Notice..., 2012, announcing an intent to grant to Fiber Optic Sensor Systems Technology Corporation, a revocable... the Navy hereby gives notice of its intent to grant to Fiber Optic Sensor Systems Technology...

Development of a directional sensitive pressure and shear sensor

NASA Astrophysics Data System (ADS)

Wang, Wei-Chih; Dee, Jeffrey; Ledoux, William; Sangeorzan, Bruce; Reinhall, Per G.

2002-06-01

Diabetes mellitus is a disease that impacts the lives of millions of people around the world. Lower limb complications associated with diabetes include the development of plantar ulcers that can lead to infection and subsequent amputation. Shear stress is thought to be a major contributing factor to ulcer development, but due in part to technical difficulties with transducing shear stress, there is no widely used shear measurement sensor. As such, we are currently developing a directionally sensitive pressure/shear sensor based on fiber optic technology. The pressure/shear sensor consists of an array of optical fibers lying in perpendicular rows and columns separated by elastomeric pads. A map of pressure and shear stress is constructed based on observed macro bending through the intensity attenuation from the physical deformation of two adjacent perpendicular fibers. The sensor has been shown to have low noise and responded linearly to applied loads. The smallest detectable force on each sensor element based on the current setup is ~0.1 lbs. (0.4N). The smallest area we have resolved in our mesh sensor is currently ~1 cm2.

Optical Fiber Networks for Remote Fiber Optic Sensors

PubMed Central

Fernandez-Vallejo, Montserrat; Lopez-Amo, Manuel

2012-01-01

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

Rapid constructions of microstructures for optical fiber sensors using a commercial CO2 laser system.

PubMed

Irawan, Rudi; Chuan, Tjin Swee; Meng, Tay Chia; Ming, Tan Khay

2008-06-27

Exposing an optical fiber core to the measurand surrounding the fiber is often used to enhance the sensitivity of an optical fiber sensor. This paper reports on the rapid fabrication of microstructures in an optical fiber using a CO₂ laser system which help exposing the optical fiber core to the measurand. The direct-write CO₂ laser system used is originally designed for engraving the polymeric material. Fabrications of microstructures such as in-fiber microhole, D-shaped fiber, in-fiber microchannel, side-sliced fiber and tapered fiber were attempted. The microstructures in the fibers were examined using a SEM and an optical microscope. Quality of microstructures shown by the SEM images and promising results from fluorescence sensor tests using in-fiber microchannels of 100μm width, 210μm depth and 10mm length show the prospect of this method for use in optical fiber sensor development. The direct-write CO₂ laser system is a flexible and fast machining tool for fabricating microstructures in an optical fiber, and can possibly be a replacement of the time consuming chemical etching and polishing methods used for microstructure fabrications of optical the fiber sensors reported in other literatures.

Rapid Constructions of Microstructures for Optical Fiber Sensors Using a Commercial CO2 Laser System

PubMed Central

Irawan, Rudi; Chuan, Tjin Swee; Meng, Tay Chia; Ming, Tan Khay

2008-01-01

Exposing an optical fiber core to the measurand surrounding the fiber is often used to enhance the sensitivity of an optical fiber sensor. This paper reports on the rapid fabrication of microstructures in an optical fiber using a CO2 laser system which help exposing the optical fiber core to the measurand. The direct-write CO2 laser system used is originally designed for engraving the polymeric material. Fabrications of microstructures such as in-fiber microhole, D-shaped fiber, in-fiber microchannel, side-sliced fiber and tapered fiber were attempted. The microstructures in the fibers were examined using a SEM and an optical microscope. Quality of microstructures shown by the SEM images and promising results from fluorescence sensor tests using in-fiber microchannels of 100μm width, 210μm depth and 10mm length show the prospect of this method for use in optical fiber sensor development. The direct-write CO2 laser system is a flexible and fast machining tool for fabricating microstructures in an optical fiber, and can possibly be a replacement of the time consuming chemical etching and polishing methods used for microstructure fabrications of optical the fiber sensors reported in other literatures. PMID:19662114

Guided wave and damage detection in composite laminates using different fiber optic sensors.

PubMed

Li, Fucai; Murayama, Hideaki; Kageyama, Kazuro; Shirai, Takehiro

2009-01-01

Guided wave detection using different fiber optic sensors and their applications in damage detection for composite laminates were systematically investigated and compared in this paper. Two types of fiber optic sensors, namely fiber Bragg gratings (FBG) and Doppler effect-based fiber optic (FOD) sensors, were addressed and guided wave detection systems were constructed for both types. Guided waves generated by a piezoelectric transducer were propagated through a quasi-isotropic carbon fiber reinforced plastic (CFRP) laminate and acquired by these fiber optic sensors. Characteristics of these fiber optic sensors in ultrasonic guided wave detection were systematically compared. Results demonstrated that both the FBG and FOD sensors can be applied in guided wave and damage detection for the CFRP laminates. The signal-to-noise ratio (SNR) of guided wave signal captured by an FOD sensor is relatively high in comparison with that of the FBG sensor because of their different physical principles in ultrasonic detection. Further, the FOD sensor is sensitive to the damage-induced fundamental shear horizontal (SH(0)) guided wave that, however, cannot be detected by using the FBG sensor, because the FOD sensor is omnidirectional in ultrasound detection and, in contrast, the FBG sensor is severely direction dependent.

Design and finite element modeling of a novel optical microsystems-based tactile sensor for minimal invasive robotic surgery

NASA Astrophysics Data System (ADS)

Ghanbari Mardasi, Amir; Ghanbari, Mahmood; Salmani Tehrani, Mehdi

2014-09-01

Although recently Minimal Invasive Robotic Surgery (MIRS) has been more addressed because of its wide range of benefits, however there are still some limitations in this regard. In order to address the shortcomings of MIRS systems, various types of tactile sensors with different sensing principles have been presented in the last few years. In the present paper a MEMS-based optical sensor, which has been recently proposed by researchers, is investigated using numerical simulation. By this type of sensors real time quantification of both dynamic and statics contact forces between the tissue and surgical instrument would be possible. The presented sensor has one moving part and works based on the intensity modulation principle of optical fibers. It is electrically-passive, MRI-compatible and it is possible to be fabricated using available standard micro fabrication techniques. The behavior of the sensor has been simulated using COMSOL MULTIPHYSICS 3.5 software. Stress analysis is conducted on the sensor to assess the deflection of the moving part of the sensor due to applied force. The optical simulation is then conducted to estimate the power loss due to the moving part deflection. Using FEM modeling, the relation between force and deflection is derived which is necessary for the calibration of the sensor.

Development of an optical fiber flow velocity sensor.

PubMed

Harada, Toshio; Kamoto, Kenji; Abe, Kyutaro; Izumo, Masaki

2009-01-01

A new optical fiber flow velocity sensor was developed by using an optical fiber information network system in sewer drainage pipes. The optical fiber flow velocity sensor operates without electric power, and the signals from the sensor can be transmitted over a long distance through the telecommunication system in the optical fiber network. Field tests were conducted to check the performance of the sensor in conduits in the pumping station and sewage pond managed by the Tokyo Metropolitan Government. Test results confirmed that the velocity sensor can be used for more than six months without any trouble even in sewer drainage pipes.

Fiber-Optic Chemical Sensors and Fiber-Optic Bio-Sensors.

PubMed

Pospíšilová, Marie; Kuncová, Gabriela; Trögl, Josef

2015-09-30

This review summarizes principles and current stage of development of fiber-optic chemical sensors (FOCS) and biosensors (FOBS). Fiber optic sensor (FOS) systems use the ability of optical fibers (OF) to guide the light in the spectral range from ultraviolet (UV) (180 nm) up to middle infrared (IR) (10 μm) and modulation of guided light by the parameters of the surrounding environment of the OF core. The introduction of OF in the sensor systems has brought advantages such as measurement in flammable and explosive environments, immunity to electrical noises, miniaturization, geometrical flexibility, measurement of small sample volumes, remote sensing in inaccessible sites or harsh environments and multi-sensing. The review comprises briefly the theory of OF elaborated for sensors, techniques of fabrications and analytical results reached with fiber-optic chemical and biological sensors.

Development and evaluation of optical fiber NH3 sensors for application in air quality monitoring

NASA Astrophysics Data System (ADS)

Huang, Yu; Wieck, Lucas; Tao, Shiquan

2013-02-01

Ammonia is a major air pollutant emitted from agricultural practices. Sources of ammonia include manure from animal feeding operations and fertilizer from cropping systems. Sensor technologies with capability of continuous real time monitoring of ammonia concentration in air are needed to qualify ammonia emissions from agricultural activities and further evaluate human and animal health effects, study ammonia environmental chemistry, and provide baseline data for air quality standard. We have developed fiber optic ammonia sensors using different sensing reagents and different polymers for immobilizing sensing reagents. The reversible fiber optic sensors have detection limits down to low ppbv levels. The response time of these sensors ranges from seconds to tens minutes depending on transducer design. In this paper, we report our results in the development and evaluation of fiber optic sensor technologies for air quality monitoring. The effect of change of temperature, humidity and carbon dioxide concentration on fiber optic ammonia sensors has been investigated. Carbon dioxide in air was found not interfere the fiber optic sensors for monitoring NH3. However, the change of humidity can cause interferences to some fiber optic NH3 sensors depending on the sensor's transducer design. The sensitivity of fiber optic NH3 sensors was found depends on temperature. Methods and techniques for eliminating these interferences have been proposed.

Optical and mechanical response of high temperature optical fiber sensors

NASA Technical Reports Server (NTRS)

Sirkis, Jim

1991-01-01

The National Aerospace Plane (NASP) will experience temperatures as high as 2500 F at critical locations in its structure. Optical fiber sensors were proposed as a means of monitoring the temperature in these critical regions by either bonding the optical fiber to, or embedding the optical fiber in, metal matrix composite (MMC) components. Unfortunately, the anticipated NASP temperature ranges exceed the glass transition region of the optical fiber glass. The attempt is made to define the operating temperature range of optical fiber sensors from both optical and mechanical perspectives. A full non-linear optical analysis was performed by modeling the optical response of an isolated sensor cyclically driven through the glass transition region.

Optical fiber-based sensors: application to chemical biology.

PubMed

Brogan, Kathryn L; Walt, David R

2005-10-01

Optical fibers have been used to develop sensors based on nucleic acids and cells. Sensors employing DNA probes have been developed for various genomics applications and microbial pathogen detection. Live cell-based sensors have enabled the monitoring of environmental toxins, and have been used for fundamental studies on populations of individual cells. Both single-core optical fiber sensors and optical fiber sensor arrays have been used for sensing based on nucleic acids and live cells.

Great prospects for fiber optics sensors

NASA Technical Reports Server (NTRS)

Hansen, T. E.

1983-01-01

Fiber optic sensors provide noise immunity and galvanic insulation at the measurement point. Interest in such sensors is increasing for these reasons. In the United States sales are expected to increase from 12 million dollars in 1981 to 180 million in 1991. Interferometric sensors based on single modus fibers deliver extremely high sensitivity, while sensors based on multi-modus fibers are more easily manufactured. The fiber optic sensors which are available today are based on point measurements. Development of fiber optic sensors in Norway is being carried out at the Central institute and has resulted in the development of medical manometers which are now undergoing clinical testing.

Recent progress in distributed optical fiber Raman photon sensors at China Jiliang University

NASA Astrophysics Data System (ADS)

Zhang, Zaixuan; Wang, Jianfeng; Li, Yi; Gong, Huaping; Yu, Xiangdong; Liu, Honglin; Jin, Yongxing; Kang, Juan; Li, Chenxia; Zhang, Wensheng; Zhang, Wenping; Niu, Xiaohui; Sun, Zhongzhou; Zhao, Chunliu; Dong, Xinyong; Jin, Shangzhong

2012-06-01

A brief review of recent progress in researches, productions and applications of full distributed fiber Raman photon sensors at China Jiliang University (CJLU) is presented. In order to improve the measurement distance, the accuracy, the space resolution, the ability of multi-parameter measurements, and the intelligence of full distributed fiber sensor systems, a new generation fiber sensor technology based on the optical fiber nonlinear scattering fusion principle is proposed. A series of new generation full distributed fiber sensors are investigated and designed, which consist of new generation ultra-long distance full distributed fiber Raman and Rayleigh scattering photon sensors integrated with a fiber Raman amplifier, auto-correction full distributed fiber Raman photon temperature sensors based on Raman correlation dual sources, full distributed fiber Raman photon temperature sensors based on a pulse coding source, full distributed fiber Raman photon temperature sensors using a fiber Raman wavelength shifter, a new type of Brillouin optical time domain analyzers (BOTDAs) integrated with a fiber Raman amplifier for replacing a fiber Brillouin amplifier, full distributed fiber Raman and Brillouin photon sensors integrated with a fiber Raman amplifier, and full distributed fiber Brillouin photon sensors integrated with a fiber Brillouin frequency shifter. The Internet of things is believed as one of candidates of the next technological revolution, which has driven hundreds of millions of class markets. Sensor networks are important components of the Internet of things. The full distributed optical fiber sensor network (Rayleigh, Raman, and Brillouin scattering) is a 3S (smart materials, smart structure, and smart skill) system, which is easy to construct smart fiber sensor networks. The distributed optical fiber sensor can be embedded in the power grids, railways, bridges, tunnels, roads, constructions, water supply systems, dams, oil and gas pipelines and other facilities, and can be integrated with wireless networks.

Embedded fiber optic sensors for bridge deck chloride penetration measurements

NASA Astrophysics Data System (ADS)

Fuhr, Peter L.; Huston, Dryver R.; MacCraith, Brian D.

1998-04-01

The use of chloride-based deicing agents to help clear U.S. highways of roadway hazards leads to associated chemical related problems. Fouling of local rivers and streams due to runoff of the waterborne chlorides is significant and has contributed to local ordinances that are attempting to force state agencies to reduce, if not eliminate, the use of these chlorides (typically at the cost of increased driving hazards). With respect to the corrosion aspects of chloride application, cracks that occur in the roadway/bridge pavement allow water to seep into the pavement carrying the chloride to the rebar with the resultant increase in corrosion. The costs of this corrosion are considerable and have led to the wide- spread use of chloride/water impermeable membranes on roadways and especially within bridges. Fiber optics sensors have repeatedly been shown to provide measurement capabilities of parameters within such reinforced concrete structures. Development of fiber optic chloride sensors capable of being embedded within a roadway or bridge deck is reported.

Cryogenic fiber optic temperature sensor and method of manufacturing the same

NASA Technical Reports Server (NTRS)

Kochergin, Vladimir (Inventor)

2012-01-01

This invention teaches the fiber optic sensors temperature sensors for cryogenic temperature range with improved sensitivity and resolution, and method of making said sensors. In more detail, the present invention is related to enhancement of temperature sensitivity of fiber optic temperature sensors at cryogenic temperatures by utilizing nanomaterials with a thermal expansion coefficient that is smaller than the thermal expansion coefficient of the optical fiber but larger in absolute value than the thermal expansion coefficient of the optical fiber at least over a range of temperatures.

Development of active and sensitive material systems based on composites

NASA Astrophysics Data System (ADS)

Asanuma, Hiroshi

2002-07-01

This paper describes new concepts proposed by the author to realize active and sensitive structural material systems. Two examples of multifunctional composites were fabricated and evaluated in this study as follows: (1) An active laminate of aluminum plate (works as muscle), epoxy film (as insulator), unidirectional CFRP prepreg (as bone and blood vessel) and copper foil electrode (to apply voltage on CFRP) was made with an embedded optical fiber multiply fractured in the CFRP layer (works as nerve), of which curvature change could be effectively monitored with the fractured optical fiber. (2) A stainless steel fiber/aluminum active composite with embedded Ti oxide/Ti composite fiber was fabricated. The Ti oxide/Ti fiber could work as a sensor for temperature by removing a part of the oxide before embedment to make a metallic contact between the embedded titanium fiber and aluminum matrix to be able to generate thermal electromotive force, and also could work as a sensor for strain and as a heater for actuation. In the both cases, the outputs from their embedded sensors can be used to control their actuations.

Improved Optical Fiber Chemical Sensors

NASA Technical Reports Server (NTRS)

Egalon, Claudio O.; Rogowski, Robert S.

1994-01-01

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.

Fiber Optic Sensors for Health Monitoring of Morphing Aircraft

NASA Technical Reports Server (NTRS)

Brown, Timothy; Wood, Karen; Childers, Brooks; Cano, Roberto; Jensen, Brian; Rogowski, Robert

2001-01-01

Fiber optic sensors are being developed for health monitoring of future aircraft. Aircraft health monitoring involves the use of strain, temperature, vibration and chemical sensors. These sensors will measure load and vibration signatures that will be used to infer structural integrity. Sine the aircraft morphing program assumes that future aircraft will be aerodynamically reconfigurable there is also a requirement for pressure, flow and shape sensors. In some cases a single fiber may be used for measuring several different parameters. The objective of the current program is to develop techniques for using optical fibers to monitor composite cure in real time during manufacture and to monitor in-service structural integrity of the composite structure. Graphite-epoxy panels were fabricated with integrated optical fibers of various types. The panels were mechanically and thermally tested to evaluate composite strength and sensor durability. Finally the performance of the fiber optic sensors was determined. Experimental results are presented evaluating the performance of embedded and surface mounted optical fibers for measuring strain, temperature and chemical composition. The performance of the fiber optic sensors was determined by direct comparison with results from more conventional instrumentation. The facilities for fabricating optical fiber and associated sensors and methods of demodulating Bragg gratings for strain measurement will be described.

Multi-channel measurement for hetero-core optical fiber sensor by using CMOS camera

NASA Astrophysics Data System (ADS)

Koyama, Yuya; Nishiyama, Michiko; Watanabe, Kazuhiro

2015-07-01

Fiber optic smart structures have been developed over several decades by the recent fiber optic sensor technology. Optical intensity-based sensors, which use LD or LEDs, can be suitable for the monitor system to be simple and cost effective. In this paper, a novel fiber optic smart structure with human-like perception has been demonstrated by using intensity-based hetero-core optical fiber sensors system with the CMOS detector. The optical intensity from the hetero-core optical fiber bend sensor is obtained as luminance spots indicated by the optical power distributions. A number of optical intensity spots are simultaneously readout by taking a picture of luminance pattern. To recognize the state of fiber optic smart structure with the hetero-core optical fibers, the template matching process is employed with Sum of Absolute Differences (SAD). A fiber optic smart glove having five optic fiber nerves have been employed to monitor hand postures. Three kinds of hand postures have been recognized by means of the template matching process. A body posture monitoring has also been developed by placing the wearable hetero-core optical fiber bend sensors on the body segments. In order for the CMOS system to be a human brain-like, the luminescent spots in the obtained picture were arranged to make the pattern corresponding to the position of body segments. As a result, it was successfully demonstrated that the proposed fiber optic smart structure could recognize eight kinds of body postures. The developed system will give a capability of human brain-like processing to the existing fiber optic smart structures.

EC93-42065-6

NASA Image and Video Library

1993-07-12

The National Aeronautics and Space Administration's Systems Research Aircraft (SRA), a highly modified F-18 jet fighter, on an early research flight over Rogers Dry Lake. The former Navy aircraft was flown by NASA's Dryden Flight Research Center at Edwards Air Force Base, California, to evaluate a number of experimental aerospace technologies in a multi-year, joint NASA/DOD/industry program. Among the more than 20 experiments flight-tested were several involving fiber optic sensor systems. Experiments developed by McDonnell-Douglas and Lockheed-Martin centered on installation and maintenace techniques for various types of fiber-optic hardware proposed for use in military and commercial aircraft, while a Parker-Hannifin experiment focused on alternative fiber-optic designs for postion measurement sensors as well as operational experience in handling optical sensor systems. Other experiments flown on this testbed aircraft included electronically-controlled control surface actuators, flush air data collection systems, "smart" skin antennae and laser-based systems. Incorporation of one or more of these technologies in future aircraft and spacecraft could result in signifigant savings in weight, maintenance and overall cost.

High-Sensitivity Fiber-Optic Ultrasound Sensors for Medical Imaging Applications

PubMed Central

Wen, H.; Wiesler, D.G.; Tveten, A.; Danver, B.; Dandridge, A.

2010-01-01

This paper presents several designs of high-sensitivity, compact fiber-optic ultrasound sensors that may be used for medical imaging applications. These sensors translate ultrasonic pulses into strains in single-mode optical fibers, which are measured with fiber-based laser interferometers at high precision. The sensors are simpler and less expensive to make than piezoelectric sensors, and are not susceptible to electromagnetic interference. It is possible to make focal sensors with these designs, and several schemes are discussed. Because of the minimum bending radius of optical fibers, the designs are suitable for single element sensors rather than for arrays. PMID:9691368

A fiber optic multi-stress monitoring system for power transformer

NASA Astrophysics Data System (ADS)

Kim, Dae-gil; Sampath, Umesh; Kim, Hyunjin; Song, Minho

2017-04-01

A fiber-optic multi-stress monitoring system which uses 4 FBG sensors and a fiber-optic mandrel acoustic emission sensor is proposed. FBG sensors and a mandrel sensor measure different types of stresses occurring in electrical power transformer, such as temperature and acoustic signals. The sensor system uses single broadband light source to address the outputs of both sensors using single fiber-optic circuitry. An athermal-packaged FBG is used to supply quasi-coherent light for the Sagnac interferometer demodulation which processes the mandrel sensor output. The proposed sensor system could simplify the optical circuit for the multi-stress measurements and enhance the cost-effectiveness of the sensor system.

High-temperature optical fiber sensors for characterization of advanced composite aerospace materials

NASA Astrophysics Data System (ADS)

Wavering, Thomas A.; Greene, Jonathan A.; Meller, Scott A.; Bailey, Timothy A.; Kozikowski, Carrie L.; Lenahan, Shannon M.; Murphy, Kent A.; Camden, Michael P.; Simmons, Larry W.

1999-01-01

Optical fiber sensors have numerous advantages over conventional sensing technologies. One such advantage is that optical fiber sensors can operate in high temperature environments. While most conventional electrical-based sensors do not operate reliably over 300 degrees C, fused silica based optical fiber sensors can survive up to 900 degrees C, and sapphire based optical fiber sensors can survive up to 2000 degrees C. Using both fused silica and sapphire technologies, we present result for high temperature strain, pressure, and temperature sensors using Extrinsic Fabry-Perot INterferometric-based and Bragg grating sensors. High temperature strain and temperature sensors were used to conduct fatigue testing of composite coupons at 600 degrees C. The results from these specific high temperature applications are presented along with future applications and directions for these sensors.

Fiber-Optic Chemical Sensors and Fiber-Optic Bio-Sensors

PubMed Central

Pospíšilová, Marie; Kuncová, Gabriela; Trögl, Josef

2015-01-01

This review summarizes principles and current stage of development of fiber-optic chemical sensors (FOCS) and biosensors (FOBS). Fiber optic sensor (FOS) systems use the ability of optical fibers (OF) to guide the light in the spectral range from ultraviolet (UV) (180 nm) up to middle infrared (IR) (10 µm) and modulation of guided light by the parameters of the surrounding environment of the OF core. The introduction of OF in the sensor systems has brought advantages such as measurement in flammable and explosive environments, immunity to electrical noises, miniaturization, geometrical flexibility, measurement of small sample volumes, remote sensing in inaccessible sites or harsh environments and multi-sensing. The review comprises briefly the theory of OF elaborated for sensors, techniques of fabrications and analytical results reached with fiber-optic chemical and biological sensors. PMID:26437407

High capacity fiber optic sensor networks using hybrid multiplexing techniques and their applications

NASA Astrophysics Data System (ADS)

Sun, Qizhen; Li, Xiaolei; Zhang, Manliang; Liu, Qi; Liu, Hai; Liu, Deming

2013-12-01

Fiber optic sensor network is the development trend of fiber senor technologies and industries. In this paper, I will discuss recent research progress on high capacity fiber sensor networks with hybrid multiplexing techniques and their applications in the fields of security monitoring, environment monitoring, Smart eHome, etc. Firstly, I will present the architecture of hybrid multiplexing sensor passive optical network (HSPON), and the key technologies for integrated access and intelligent management of massive fiber sensor units. Two typical hybrid WDM/TDM fiber sensor networks for perimeter intrusion monitor and cultural relics security are introduced. Secondly, we propose the concept of "Microstructure－Optical X Domin Refecltor (M-OXDR)" for fiber sensor network expansion. By fabricating smart micro-structures with the ability of multidimensional encoded and low insertion loss along the fiber, the fiber sensor network of simple structure and huge capacity more than one thousand could be achieved. Assisted by the WDM/TDM and WDM/FDM decoding methods respectively, we built the verification systems for long-haul and real-time temperature sensing. Finally, I will show the high capacity and flexible fiber sensor network with IPv6 protocol based hybrid fiber/wireless access. By developing the fiber optic sensor with embedded IPv6 protocol conversion module and IPv6 router, huge amounts of fiber optic sensor nodes can be uniquely addressed. Meanwhile, various sensing information could be integrated and accessed to the Next Generation Internet.

Fiber-optic liquid level sensor

DOEpatents

Weiss, Jonathan D.

1991-01-01

A fiber-optic liquid level sensor measures the height of a column of liquid through the hydrostatic pressure it produces. The sensor employs a fiber-optic displacement sensor to detect the pressure-induced displacement of the center of a corrugated diaphragm.

Multi-Stress Monitoring System with Fiber-Optic Mandrels and Fiber Bragg Grating Sensors in a Sagnac Loop

PubMed Central

Kim, Hyunjin; Sampath, Umesh; Song, Minho

2015-01-01

Fiber Bragg grating sensors are placed in a fiber-optic Sagnac loop to combine the grating temperature sensors and the fiber-optic mandrel acoustic emission sensors in single optical circuit. A wavelength-scanning fiber-optic laser is used as a common light source for both sensors. A fiber-optic attenuator is placed at a specific position in the Sagnac loop in order to separate buried Bragg wavelengths from the Sagnac interferometer output. The Bragg wavelength shifts are measured with scanning band-pass filter demodulation and the mandrel output is analyzed by applying a fast Fourier transform to the interference signal. This hybrid-scheme could greatly reduce the size and the complexity of optical circuitry and signal processing unit, making it suitable for low cost multi-stress monitoring of large scale power systems. PMID:26230700

Nuclear power plant prestressed concrete containment vessel structure monitoring during integrated leakage rate test using three kinds of fiber optic sensors

NASA Astrophysics Data System (ADS)

Liao, Kaixing; Li, Jinke; Kong, Xianglong; Sun, Changsen; Zhao, Xuefeng

2017-04-01

After years of operation, the safety of the prestressed concrete containment vessel (PCCV) structure of Nuclear Power Plant (NPP) is an important aspect. In order to detect the strength degradation and the structure deformation, several sensors such as vibrating wire strain gauge, invar wires and pendulums were installed in PCCV. However, the amounts of sensors above are limited due to the cost. Due to the well durability of fiber optic sensors, three kinds of fiber optic sensors were chosen to install on the surface of PCCV to monitor the deformation during Integrated Leakage Rate Test (ILRT). The three kinds of fiber optic sensors which had their own advantages and disadvantages are Fiber Bragg Grating (FBG), white light interferometry (WLI) and Brillouin Optical Time Domain Analysis (BOTDA). According to the measuring data, the three fiber optic sensors worked well during the ILRT. After the ILRT, the monitoring strain was recoverable thus the PCCV was still in the elastic stage. If these three kinds of fiber optic sensors are widely used in the PCCV, the unusual deformations are easier to detect. As a consequence, the three fiber optic sensors have good potential in the structure health monitoring of PCCV.

Emerging technology in fiber optic sensors

NASA Astrophysics Data System (ADS)

Dyott, Richard B.

1991-03-01

Some recent innovations in interferoinetric fiber optic sensors include special fibers new components and sensor systems. Many of the concepts have precedents in microwaves. 1. GENERAL PRINCIPLES The application of optical fibers to sensors is diffuse compared with their application to optical communications which is essentially focused on the single problem of how to get information from A to B. A fiber sensor is viable when it can do something not possible with better than more cheaply than any existing method. The probability of the emergence of a new sensor depends on the length of time that a need for the sensor and the possibility of meeting that need have co-existed regardless of whether the need or the possibility has appeared first. 2. TYPES OF SENSOR Fiber sensors can be divided into: a) Multimode fiber sensors which depend on amplitude effects b) Single mode (single path) fiber sensors which depend on phase effects. Since multimode fiber has existed for many decades the emergence of a new multimode sensor depends mostly on the discovery of a new need for such a sensor. On the other hand single mode/single path (i. e. polarization maintaining) fiber is relatively new and so is still being applied to existing needs. This is particularly so of recent innovations in fibers and components. SPIE Vol. 1396 Applications of Optical Engineering Proceedings of OE/Midwest ''90 / 709

Strain and dynamic measurements using fiber optic sensors embedded into graphite/epoxy tubes

NASA Technical Reports Server (NTRS)

Dehart, D. W.; Doederlein, T.; Koury, J.; Rogowski, R. S.; Heyman, J. S.; Holben, M. S., Jr.

1989-01-01

Graphite/epoxy tubes were fabricated with embedded optical fibers to evaluate the feasibility of monitoring strains with a fiber optic technique. Resistance strain gauges were attached to the tubes to measure strain at four locations along the tube for comparison with the fiber optic sensors. Both static and dynamic strain measurements were made with excellent agreement between the embedded fiber optic strain sensor and the strain gauges. Strain measurements of 10(exp -7) can be detected with the optical phase locked loop (OPLL) system using optical fiber. Because of their light weight, compatibility with composites, immunity to electromagnetic interference, and based on the static and dynamic results obtained, fiber optic sensors embedded in composites may be useful as the sensing component of smart structures.

High density array fabrication and readout method for a fiber optic biosensor

DOEpatents

Pinkel, Daniel; Gray, Joe

1997-01-01

The invention relates to the fabrication and use of biosensors comprising a plurality of optical fibers each fiber having attached to its "sensor end" biological "binding partners" (molecules that specifically bind other molecules to form a binding complex such as antibody-antigen, lectin-carbohydrate, nucleic acid-nucleic acid, biotin-avidin, etc.). The biosensor preferably bears two or more different species of biological binding partner. The sensor is fabricated by providing a plurality of groups of optical fibers. Each group is treated as a batch to attach a different species of biological binding partner to the sensor ends of the fibers comprising that bundle. Each fiber, or group of fibers within a bundle, may be uniquely identified so that the fibers, or group of fibers, when later combined in an array of different fibers, can be discretely addressed. Fibers or groups of fibers are then selected and discretely separated from different bundles. The discretely separated fibers are then combined at their sensor ends to produce a high density sensor array of fibers capable of assaying simultaneously the binding of components of a test sample to the various binding partners on the different fibers of the sensor array. The transmission ends of the optical fibers are then discretely addressed to detectors--such as a multiplicity of optical sensors. An optical signal, produced by binding of the binding partner to its substrate to form a binding complex, is conducted through the optical fiber or group of fibers to a detector for each discrete test. By examining the addressed transmission ends of fibers, or groups of fibers, the addressed transmission ends can transmit unique patterns assisting in rapid sample identification by the sensor.

High density array fabrication and readout method for a fiber optic biosensor

DOEpatents

Pinkel, Daniel; Gray, Joe; Albertson, Donna G.

2000-01-01

The invention relates to the fabrication and use of biosensors comprising a plurality of optical fibers each fiber having attached to its "sensor end" biological "binding partners" (molecules that specifically bind other molecules to form a binding complex such as antibody-antigen, lectin-carbohydrate, nucleic acid-nucleic acid, biotin-avidin, etc.). The biosensor preferably bears two or more different species of biological binding partner. The sensor is fabricated by providing a plurality of groups of optical fibers. Each group is treated as a batch to attach a different species of biological binding partner to the sensor ends of the fibers comprising that bundle. Each fiber, or group of fibers within a bundle, may be uniquely identified so that the fibers, or group of fibers, when later combined in an array of different fibers, can be discretely addressed. Fibers or groups of fibers are then selected and discretely separated from different bundles. The discretely separated fibers are then combined at their sensor ends to produce a high density sensor array of fibers capable of assaying simultaneously the binding of components of a test sample to the various binding partners on the different fibers of the sensor array. The transmission ends of the optical fibers are then discretely addressed to detectors--such as a multiplicity of optical sensors. An optical signal, produced by binding of the binding partner to its substrate to form a binding complex, is conducted through the optical fiber or group of fibers to a detector for each discrete test. By examining the addressed transmission ends of fibers, or groups of fibers, the addressed transmission ends can transmit unique patterns assisting in rapid sample identification by the sensor.

High density array fabrication and readout method for a fiber optic biosensor

DOEpatents

Pinkel, Daniel; Gray, Joe; Albertson, Donna G.

2002-01-01

The invention relates to the fabrication and use of biosensors comprising a plurality of optical fibers each fiber having attached to its "sensor end" biological "binding partners" (molecules that specifically bind other molecules to form a binding complex such as antibody-antigen, lectin-carbohydrate, nucleic acid-nucleic acid, biotin-avidin, etc.). The biosensor preferably bears two or more different species of biological binding partner. The sensor is fabricated by providing a plurality of groups of optical fibers. Each group is treated as a batch to attach a different species of biological binding partner to the sensor ends of the fibers comprising that bundle. Each fiber, or group of fibers within a bundle, may be uniquely identified so that the fibers, or group of fibers, when later combined in an array of different fibers, can be discretely addressed. Fibers or groups of fibers are then selected and discretely separated from different bundles. The discretely separated fibers are then combined at their sensor ends to produce a high density sensor array of fibers capable of assaying simultaneously the binding of components of a test sample to the various binding partners on the different fibers of the sensor array. The transmission ends of the optical fibers are then discretely addressed to detectors--such as a multiplicity of optical sensors. An optical signal, produced by binding of the binding partner to its substrate to form a binding complex, is conducted through the optical fiber or group of fibers to a detector for each discrete test. By examining the addressed transmission ends of fibers, or groups of fibers, the addressed transmission ends can transmit unique patterns assisting in rapid sample identification by the sensor.

High density array fabrication and readout method for a fiber optic biosensor

DOEpatents

Pinkel, D.; Gray, J.

1997-11-25

The invention relates to the fabrication and use of biosensors comprising a plurality of optical fibers each fiber having attached to its ``sensor end`` biological ``binding partners`` (molecules that specifically bind other molecules to form a binding complex such as antibody-antigen, lectin-carbohydrate, nucleic acid-nucleic acid, biotin-avidin, etc.). The biosensor preferably bears two or more different species of biological binding partner. The sensor is fabricated by providing a plurality of groups of optical fibers. Each group is treated as a batch to attach a different species of biological binding partner to the sensor ends of the fibers comprising that bundle. Each fiber, or group of fibers within a bundle, may be uniquely identified so that the fibers, or group of fibers, when later combined in an array of different fibers, can be discretely addressed. Fibers or groups of fibers are then selected and discretely separated from different bundles. The discretely separated fibers are then combined at their sensor ends to produce a high density sensor array of fibers capable of assaying simultaneously the binding of components of a test sample to the various binding partners on the different fibers of the sensor array. The transmission ends of the optical fibers are then discretely addressed to detectors--such as a multiplicity of optical sensors. An optical signal, produced by binding of the binding partner to its substrate to form a binding complex, is conducted through the optical fiber or group of fibers to a detector for each discrete test. By examining the addressed transmission ends of fibers, or groups of fibers, the addressed transmission ends can transmit unique patterns assisting in rapid sample identification by the sensor. 9 figs.

Optical Fiber Sensors for Advanced Civil Structures

NASA Astrophysics Data System (ADS)

de Vries, Marten Johannes Cornelius

1995-01-01

The objective of this dissertation is to develop, analyze, and implement optical fiber-based sensors for the nondestructive quantitative evaluation of advanced civil structures. Based on a comparative evaluation of optical fiber sensors that may be used to obtain quantitative information related to physical perturbations in the civil structure, the extrinsic Fabry-Perot interferometric (EFPI) optical fiber sensor is selected as the most attractive sensor. The operation of the EFPI sensor is explained using the Kirchhoff diffraction approach. As is shown in this dissertation, this approach better predicts the signal-to-noise ratio as a function of gap length than methods employed previously. The performance of the optical fiber sensor is demonstrated in three different implementations. In the first implementation, performed with researchers in the Civil Engineering Department at the University of Southern California in Los Angeles, optical fiber sensors were used to obtain quantitative strain information from reinforced concrete interior and exterior column-to-beam connections. The second implementation, performed in cooperation with researchers at the United States Bureau of Mines in Spokane, Washington, used optical fiber sensors to monitor the performance of roof bolts used in mines. The last implementation, performed in cooperation with researchers at the Turner-Fairbanks Federal Highway Administration Research Center in McLean, Virginia, used optical fiber sensors, attached to composite prestressing strands used for reinforcing concrete, to obtain absolute strain information. Multiplexing techniques including time, frequency and wavelength division multiplexing are briefly discussed, whereas the principles of operation of spread spectrum and optical time domain reflectometery (OTDR) are discussed in greater detail. Results demonstrating that spread spectrum and OTDR techniques can be used to multiplex optical fiber sensors are presented. Finally, practical considerations that have to be taken into account when implementing optical fiber sensors into a civil structure environment are discussed, and possible solutions to some of these problems are proposed.

Realization of fiber optic displacement sensors

NASA Astrophysics Data System (ADS)

Guzowski, Bartlomiej; Lakomski, Mateusz

2018-03-01

Fiber optic sensors are very promising because of their inherent advantages such as very small size, hard environment tolerance and impact of electromagnetic fields. In this paper three different types of Intensity Fiber Optic Displacement Sensors (I-FODS) are presented. Three configurations of I-FODS were realized in two varieties. In the first one, the cleaved multimode optical fibers (MMF) were used to collect reflected light, while in the second variety the MMF ended with ball lenses were chosen. To ensure an accurate alignment of optical fibers in the sensor head the MTP C9730 optical fiber ferrules were used. In this paper the influence of distribution of transmitting and detecting optical fibers on sensitivity and linear range of operation of developed I-FODS were investigated. We have shown, that I-FODS with ball lenses receive average 10.5% more reflected power in comparison to the cleaved optical fibers and they increase linearity range of I-FODS by 33%. In this paper, an analysis of each type of the realized sensor and detailed discussion are given.

Fiber optic sensor technology - An opportunity for smart aerospace structures

NASA Technical Reports Server (NTRS)

Heyman, J. S.; Rogowski, R. S.; Claus, R. O.

1988-01-01

Fiber optic sensors provide the opportunity for fabricating materials with internal sensors which can serve as lifetime health monitors, analogous to a central nervous system. The embedded fiber optic sensors can be interrogated by various techniques to measure internal strain, temperature, pressure, acoustic waves and other parameters indicative of structural integrity. Experiments have been conducted with composite samples with embedded sensors to measure strain using optical time domain reflectometry, modal interference and an optical phase locked loop. Fiber optic sensors have been developed to detect acoustic emission and impact damage and have been demonstrated for cure monitoring. These sensors have the potential for lifetime monitoring of structural properties, providing real time nondestructive evaluation.

SU-E-T-159: Characteristics of Fiber-Optic Radiation Sensor for Proton Therapeutic Beam

DOE Office of Scientific and Technical Information (OSTI.GOV)

Son, J; Kim, M; Hwang, U

Purpose: A fiber-optic radiation sensor using Cerenkov radiation has been widely studied for use as a dosimeter for proton therapeutic beam. Although the fiber-optic radiation sensor has already been investigated for proton therapeutic, it has been examined relatively little work for clinical therapeutic proton beams. In this study, we evaluated characteristics of a fiber-optic radiation sensor for clinical therapeutic proton beams. We experimentally evaluated dose-rate dependence, dose response and energy dependence for the proton beam. Methods: A fiber-optic radiation sensor was placed in a water phantom. Beams with energies of low, middle and high were used in the passively-scattered protonmore » therapeutic beam at the National Cancer Center in Korea. The sensor consists of two plastic optical fibers (POF). A reference POF and 2 cm longer POF were used to utilize the subtraction method for having sensitive volume. Each POF is optically coupled to the Multi-Anode Photo Multiplier Tube (MAPMT) and the MAPMT signals are processed using National Instruments Data Acquisition System (NI-DAQ). We were investigated dosimetric properties including dose-rate dependence, dose response and energy dependence. Results: We have successfully evaluated characteristics of a fiber optic radiation sensor using Cerenkov radiation. The fiber-optic radiation sensor showed the dose response linearity and low energy dependence. In addition, as the dose-rate was increased, Cerenkov radiation increased linearly. Conclusion: We evaluated the basic characteristics of the fiber optic radiation sensor, the dosimetry tool, to raise the quality of proton therapy. Based on the research, we developed a real time dosimetry system of the optic fiber to confirm the real time beam position and energy for therapeutic proton pencil beam.« less

Development of a miniaturized optical viscosity sensor with an optical surface tracking system

NASA Astrophysics Data System (ADS)

Abe, H.; Nagamachi, R.; Taguchi, Y.; Nagasaka, Y.

2010-02-01

A new viscosity sensor enabling non-contact measurement at high speed, with less sample volume and high stability is required in a broad field. For example, in the industrial field, process control by real time monitoring of viscosity can enhance the quality of coating films and the process yield such as conductive films and optical films. Therefore, we have developed a new miniaturized optical viscosity sensor, namely MOVS (Miniaturized Optical Viscosity Sensor), based on a laser-induced capillary wave (LiCW) method which can meet the requirements above. In the MOVS, viscosity is estimated by observing the damping oscillation of LiCW, which is generated by an interference of two excitation laser beams on a liquid surface. By irradiating a probing laser on LiCW, a first order diffracted beam containing information of sample viscosity, is generated. The intensity of the reflected beam is utilized to control the distance between liquid-level and the sensor. The newly integrated optical surface tracking system makes possible the stable viscosity measurement in the presence of disturbance such as evaporation and external vibration. MOVS consists of five U-grooves fabricated by MEMS (Micro Electro Mechanical Systems) process to possess the optical fibers (photonic crystal fibers and fusion-spliced lensed fibers). In this study, by integrating the optical surface tracking system on the chip, nanosecond order damping oscillation of LiCW is successfully observed in the presence of external forced vibration, high speed evaporation (speed of 1 micrometer per second) and drying process of a liquid film (thickness of hundreds micrometer order).

Fiber Optic Sensors for Health Monitoring of Morphing Airframes. Part 1; Bragg Grating Strain and Temperature Sensor

NASA Technical Reports Server (NTRS)

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

2000-01-01

Fiber optic sensors are being developed for health monitoring of future aircraft. Aircraft health monitoring involves the use of strain, temperature, vibration and chemical sensors to infer integrity of the aircraft structure. Part 1 of this two part series describes sensors that will measure load and temperature signatures of these structures. In some cases a single fiber may be used for measuring these parameters. Part 2 will describe techniques for using optical fibers to monitor composite cure in real time during manufacture and to monitor in-service integrity of composite structures using a single fiber optic sensor capable of measuring multiple chemical and physical parameters. The facilities for fabricating optical fiber and associated sensors and the methods of demodulating Bragg gratings for strain measurement will be described.

Reliability improvement methods for sapphire fiber temperature sensors

NASA Astrophysics Data System (ADS)

Schietinger, C.; Adams, B.

1991-08-01

Mechanical, optical, electrical, and software design improvements can be brought to bear in the enhancement of fiber-optic sapphire-fiber temperature measurement tool reliability in harsh environments. The optical fiber thermometry (OFT) equipment discussed is used in numerous process industries and generally involves a sapphire sensor, an optical transmission cable, and a microprocessor-based signal analyzer. OFT technology incorporating sensors for corrosive environments, hybrid sensors, and two-wavelength measurements, are discussed.

Fiber-Optic Strain Sensors With Linear Characteristics

NASA Technical Reports Server (NTRS)

Egalon, Claudio O.; Rogowski, Robert S.

1993-01-01

Fiber-optic modal domain strain sensors having linear characteristics over wide range of strains proposed. Conceived in effort to improve older fiber-optic strain sensors. Linearity obtained by appropriate choice of design parameters. Pattern of light and dark areas at output end of optical fiber produced by interference between electromagnetic modes in which laser beam propagates in fiber. Photodetector monitors intensity at one point in pattern.

Optical Fiber Sensors Based on Fiber Ring Laser Demodulation Technology

PubMed Central

Xie, Wen-Ge; Wang, Peng-Zhao; Wang, Jian-Zhang

2018-01-01

A review for optical fiber sensors based on fiber ring laser (FRL) demodulation technology is presented. The review focuses on the principles, main structures, and the sensing performances of different kinds of optical fiber sensors based on FRLs. First of all, the theory background of the sensors has been discussed. Secondly, four different types of sensors are described and compared, which includes Mach–Zehnder interferometer (MZI) typed sensors, Fabry–Perot interferometer (FPI) typed sensors, Sagnac typed sensors, and fiber Bragg grating (FBG) typed sensors. Typical studies and main properties of each type of sensors are presented. Thirdly, a comparison of different types of sensors are made. Finally, the existing problems and future research directions are pointed out and analyzed. PMID:29419745

Optical Fiber Sensors Based on Fiber Ring Laser Demodulation Technology.

PubMed

Xie, Wen-Ge; Zhang, Ya-Nan; Wang, Peng-Zhao; Wang, Jian-Zhang

2018-02-08

A review for optical fiber sensors based on fiber ring laser (FRL) demodulation technology is presented. The review focuses on the principles, main structures, and the sensing performances of different kinds of optical fiber sensors based on FRLs. First of all, the theory background of the sensors has been discussed. Secondly, four different types of sensors are described and compared, which includes Mach-Zehnder interferometer (MZI) typed sensors, Fabry-Perot interferometer (FPI) typed sensors, Sagnac typed sensors, and fiber Bragg grating (FBG) typed sensors. Typical studies and main properties of each type of sensors are presented. Thirdly, a comparison of different types of sensors are made. Finally, the existing problems and future research directions are pointed out and analyzed.

Control systems using modal domain optical fiber sensors for smart structure applications

NASA Technical Reports Server (NTRS)

Lindner, Douglas K.; Reichard, Karl M.

1991-01-01

Recently, a new class of sensors has emerged for structural control which respond to environmental changes over a significant gauge length; these sensors are called distributed-effect sensors. These sensors can be fabricated with spatially varying sensitivity to the distributed measurand, and can be configured to measure a variety of structural parameters which can not be measured directly using point sensors. Examples of distributed-effect sensors include piezoelectric film, holographic sensors, and modal domain optical fiber sensors. Optical fiber sensors are particularly attractive for smart structure applications because they are flexible, have low mass, and can easily be embedded directly into materials. In this paper we describe the implementation of weighted modal domain optical fiber sensors. The mathematical model of the modal domain optical fiber sensor model is described and used to derive an expression for the sensor sensitivity. The effects of parameter variations on the sensor sensitivity are demonstrated to illustrate methods of spatially varying the sensor sensitivity.

Realization of a fiber optic sensor detecting the presence of a liquid

NASA Astrophysics Data System (ADS)

Guzowski, B.; Łakomski, M.; Nowogrodzki, K.

2016-11-01

Over the past thirty years, optical fibers have revolutionized the telecommunication market. Fiber optics play also important roles in other numerous applications. One of these applications is fiber sensing - very fast developing area. In this paper, realization of different configurations of a fiber optic sensor detecting the presence of liquid is presented. In the presented sensor, two multimode fibers (MMF) are placed opposite each other, where the first one transmits the light radiation, while the second one is a receiver. Due to the small size of the core (50 μm diameter), they had to be precisely positioned. Therefore the optical fibers were placed in the etched channels in the silicon substrate. In order to make sensors more sensitive, ball-lensed optical fibers were used. Four different diameters of lenses were examined. Sensitivity to the presence of liquids was compared in all realized sensors. Moreover, the influence of distance between the transmitting and receiving optical fiber on the received optical power is also described in this paper. All developed sensors were tested at 1300 nm wavelength. In the last part of this paper the detailed discussion is given.

Optical fiber sensor having a sol-gel fiber core and a method of making

DOEpatents

Tao, Shiquan; Jindal, Rajeev; Winstead, Christopher; Singh, Jagdish P.

2006-06-06

A simple, economic wet chemical procedure is described for making sol-gel fibers. The sol-gel fibers made from this process are transparent to ultraviolet, visible and near infrared light. Light can be guided in these fibers by using an organic polymer as a fiber cladding. Alternatively, air can be used as a low refractive index medium. The sol-gel fibers have a micro pore structure which allows molecules to diffuse into the fiber core from the surrounding environment. Chemical and biochemical reagents can be doped into the fiber core. The sol-gel fiber can be used as a transducer for constructing an optical fiber sensor. The optical fiber sensor having an active sol-gel fiber core is more sensitive than conventional evanescent wave absorption based optical fiber sensors.

Fiber-optic push-pull sensor systems

NASA Technical Reports Server (NTRS)

Gardner, David L.; Brown, David A.; Garrett, Steven L.

1991-01-01

Fiber-optic push-pull sensors are those which exploit the intrinsically differential nature of an interferometer with concommitant benefits in common-mode rejection of undesired effects. Several fiber-optic accelerometer and hydrophone designs are described. Additionally, the recent development at the Naval Postgraduate School of a passive low-cost interferometric signal demodulator permits the development of economical fiber-optic sensor systems.

Optical Fiber Grating Hydrogen Sensors: A Review

PubMed Central

Dai, Jixiang; Zhu, Li; Wang, Gaopeng; Xiang, Feng; Qin, Yuhuan; Wang, Min; Yang, Minghong

2017-01-01

In terms of hydrogen sensing and detection, optical fiber hydrogen sensors have been a research issue due to their intrinsic safety and good anti-electromagnetic interference. Among these sensors, hydrogen sensors consisting of fiber grating coated with sensitive materials have attracted intensive research interests due to their good reliability and distributed measurements. This review paper mainly focuses on optical fiber hydrogen sensors associated with fiber gratings and various materials. Their configurations and sensing performances proposed by different groups worldwide are reviewed, compared and discussed in this paper. Meanwhile, the challenges for fiber grating hydrogen sensors are also addressed. PMID:28287499

Optical Fiber Grating Hydrogen Sensors: A Review.

PubMed

Dai, Jixiang; Zhu, Li; Wang, Gaopeng; Xiang, Feng; Qin, Yuhuan; Wang, Min; Yang, Minghong

2017-03-12

In terms of hydrogen sensing and detection, optical fiber hydrogen sensors have been a research issue due to their intrinsic safety and good anti-electromagnetic interference. Among these sensors, hydrogen sensors consisting of fiber grating coated with sensitive materials have attracted intensive research interests due to their good reliability and distributed measurements. This review paper mainly focuses on optical fiber hydrogen sensors associated with fiber gratings and various materials. Their configurations and sensing performances proposed by different groups worldwide are reviewed, compared and discussed in this paper. Meanwhile, the challenges for fiber grating hydrogen sensors are also addressed.

Looped back fiber mode for reduction of false alarm in leak detection using distributed optical fiber sensor.

PubMed

Chelliah, Pandian; Murgesan, Kasinathan; Samvel, Sosamma; Chelamchala, Babu Rao; Tammana, Jayakumar; Nagarajan, Murali; Raj, Baldev

2010-07-10

Optical-fiber-based sensors have inherent advantages, such as immunity to electromagnetic interference, compared to the conventional sensors. Distributed optical fiber sensor (DOFS) systems, such as Raman and Brillouin distributed temperature sensors are used for leak detection. The inherent noise of fiber-based systems leads to occasional false alarms. In this paper, a methodology is proposed to overcome this. This uses a looped back fiber mode in DOFS and voting logic is employed to considerably reduce the false alarm rate.

Highly Sensitive and Wide-Dynamic-Range Multichannel Optical-Fiber pH Sensor Based on PWM Technique.

PubMed

Khan, Md Rajibur Rahaman; Kang, Shin-Won

2016-11-09

In this study, we propose a highly sensitive multichannel pH sensor that is based on an optical-fiber pulse width modulation (PWM) technique. According to the optical-fiber PWM method, the received sensing signal's pulse width changes when the optical-fiber pH sensing-element of the array comes into contact with pH buffer solutions. The proposed optical-fiber PWM pH-sensing system offers a linear sensing response over a wide range of pH values from 2 to 12, with a high pH-sensing ability. The sensitivity of the proposed pH sensor is 0.46 µs/pH, and the correlation coefficient R² is approximately 0.997. Additional advantages of the proposed optical-fiber PWM pH sensor include a short/fast response-time of about 8 s, good reproducibility properties with a relative standard deviation (RSD) of about 0.019, easy fabrication, low cost, small size, reusability of the optical-fiber sensing-element, and the capability of remote sensing. Finally, the performance of the proposed PWM pH sensor was compared with that of potentiometric, optical-fiber modal interferometer, and optical-fiber Fabry-Perot interferometer pH sensors with respect to dynamic range width, linearity as well as response and recovery times. We observed that the proposed sensing systems have better sensing abilities than the above-mentioned pH sensors.

Highly Sensitive and Wide-Dynamic-Range Multichannel Optical-Fiber pH Sensor Based on PWM Technique

PubMed Central

Khan, Md. Rajibur Rahaman; Kang, Shin-Won

2016-01-01

In this study, we propose a highly sensitive multichannel pH sensor that is based on an optical-fiber pulse width modulation (PWM) technique. According to the optical-fiber PWM method, the received sensing signal’s pulse width changes when the optical-fiber pH sensing-element of the array comes into contact with pH buffer solutions. The proposed optical-fiber PWM pH-sensing system offers a linear sensing response over a wide range of pH values from 2 to 12, with a high pH-sensing ability. The sensitivity of the proposed pH sensor is 0.46 µs/pH, and the correlation coefficient R2 is approximately 0.997. Additional advantages of the proposed optical-fiber PWM pH sensor include a short/fast response-time of about 8 s, good reproducibility properties with a relative standard deviation (RSD) of about 0.019, easy fabrication, low cost, small size, reusability of the optical-fiber sensing-element, and the capability of remote sensing. Finally, the performance of the proposed PWM pH sensor was compared with that of potentiometric, optical-fiber modal interferometer, and optical-fiber Fabry–Perot interferometer pH sensors with respect to dynamic range width, linearity as well as response and recovery times. We observed that the proposed sensing systems have better sensing abilities than the above-mentioned pH sensors. PMID:27834865

Fiber-optic proximity sensor

NASA Technical Reports Server (NTRS)

Bejczy, A. K.; Hermann, W. A.; Primus, H. C.

1980-01-01

Proximity sensor for mechanical hand of remote manipulator incorporates fiber optics to conduct signals between light source and light detector. Fiber optics are not prone to noise from electromagnetic interference and radio-frequency interference as are sensors using long electrical cables.

Fiber optic coupled optical sensor

DOEpatents

Fleming, Kevin J.

2001-01-01

A displacement sensor includes a first optical fiber for radiating light to a target, and a second optical fiber for receiving light from the target. The end of the first fiber is adjacent and not axially aligned with the second fiber end. A lens focuses light from the first fiber onto the target and light from the target onto the second fiber.

Specialty fibers for fiber optic sensor application

NASA Astrophysics Data System (ADS)

Bennett, K.; Koh, J.; Coon, J.; Chien, C. K.; Artuso, A.; Chen, X.; Nolan, D.; Li, M.-J.

2007-09-01

Over the last several years, Fiber Optic Sensor (FOS) applications have seen an increased acceptance in many areas including oil & gas production monitoring, gyroscopes, current sensors, structural sensing and monitoring, and aerospace applications. High level optical and mechanical reliability of optical fiber is necessary to guarantee reliable performance of FOS. In this paper, we review recent research and development activities on new specialty fibers. We discuss fiber design concepts and present both modeling and experimental results. The main approaches to enhancing fiber attributes include new index profile design and fiber coating modification.

Fiber optic sensors IV; Proceedings of the Third European Congress on Optics, The Hague, Netherlands, Mar. 13, 14, 1990

NASA Technical Reports Server (NTRS)

Kersten, Ralf T. (Editor)

1990-01-01

Recent advances in fiber-optic sensor (FOS) technology are examined in reviews and reports. Sections are devoted to components for FOSs, special fibers for FOSs, interferometry, FOS applications, and sensing principles and influence. Particular attention is given to solder glass sealing technology for FOS packaging, the design of optical-fiber current sensors, pressure and temperature effects on beat length in highly birefringent optical fibers, a pressure FOS based on vibrating-quartz-crystal technology, remote sensing of flammable gases using a fluoride-fiber evanescent probe, a displacement sensor with electronically scanned white-light interferometer, the use of multimode laser diodes in low-coherence coupled-cavity interferometry, electronic speckle interferometry compensated for environmentally induced phase noise, a dual-resolution noncontact vibration and displacement sensor based on a two-wavelength source, and fiber optics in composite materials.

Characterization of light transmissions in various optical fibers with proton beam

NASA Astrophysics Data System (ADS)

Song, Young Beom; Kim, Hye Jin; Kim, Mingeon; Lee, Bongsoo; Shin, Sang Hun; Yoo, Wook Jae; Jang, Kyoung Won; Hwang, Sung Won

2017-12-01

As a feasibility study on the development of a fiber-optic radiation sensor for proton therapy dosimetry, we characterized light transmissions of various commercial optical fibers such as silica and plastic based optical fibers by the irradiation of proton beams. In this study, we measured light transmission spectra of optical fibers as a function of absorbed doses of proton beams using a deuterium & tungsten halogen lamps and a spectrometer. To be used as a fiber-optic radiation sensor, the optical fibers should have the radiation resistant characteristics and provide stable output signals during the proton beam irradiation. In this study, we could select suitable optical fibers to be used in the fiber-optic radiation sensor without quenching effects for proton therapy dosimetry. As a result, the light transmittance of the optical fibers had decreasing trends with increasing absorbed dose as expected.

Fundamental concepts of integrated and fiber optic sensors

NASA Technical Reports Server (NTRS)

Tuma, Margaret L.

1995-01-01

This chapter discusses fiber optic and integrated optic sensor concepts. Unfortunately, there is no standard method to categorize these sensor concepts. Here, fiber optic and integrated optic sensor concepts will be categorized by the primary modulation technique. These modulation techniques have been classified as: intensity, phase, wavelength, polarization, and time/frequency modulation. All modulate the output light with respect to changes in the physical or chemical property to be measured. Each primary modulation technique is then divided into fiber optic and integrated optic sections which are treated independently. For each sensor concept, possible sensor applications are discussed. The sensors and references discussed are not exhaustive, but sufficient to give the reader an overview of sensor concepts developed to date. Sensor multiplexing techniques such as wavelength division, time division, and frequency division will not be discussed as they are beyond the scope of this report.

Architecture for fiber-optic sensors and actuators in aircraft propulsion systems

NASA Technical Reports Server (NTRS)

Glomb, W. L., Jr.

1990-01-01

This paper describes a design for fiber-optic sensing and control in advanced aircraft Electronic Engine Control (EEC). The recommended architecture is an on-engine EEC which contains electro-optic interface circuits for fiber-optic sensors. Size and weight are reduced by multiplexing arrays of functionally similar sensors on a pairs of optical fibers to common electro-optical interfaces. The architecture contains interfaces to seven sensor groups. Nine distinct fiber-optic sensor types were found to provide the sensing functions. Analysis revealed no strong discriminator (except reliability of laser diodes and remote electronics) on which to base a selection of preferred common interface type. A hardware test program is recommended to assess the relative maturity of the technologies and to determine real performance in the engine environment.

Characteristic Analysis Light Intensity Sensor Based On Plastic Optical Fiber At Various Configuration

NASA Astrophysics Data System (ADS)

Arifin, A.; Lusiana; Yunus, Muhammad; Dewang, Syamsir

2018-03-01

This research discusses the light intensity sensor based on plastic optical fiber. This light intensity sensor is made of plastic optical fiber consisting of two types, namely which is cladding and without cladding. Plastic optical fiber used multi-mode step-index type made of polymethyl metacrylate (PMMA). The infrared LED emits light into the optical fiber of the plastic and is subsequently received by the phototransistor to be converted to an electric voltage. The sensor configuration is made with three models: straight configuration, U configuration and gamma configuration with cladding and without cladding. The measured light source uses a 30 Watt high power LED with a light intensity of 0 to 10 Klux. The measured light intensity will affect the propagation of light inside the optical fiber sensor. The greater the intensity of the measured light, the greater the output voltage that is read on the computer. The results showed that the best optical fiber sensor characteristics were obtained in U configuration. Sensors with U-configuration without cladding had the best sensitivity and resolution values of 0.0307 volts/Klux and 0.0326 Klux. The advantages of this measuring light intensity based on the plastic optical fiber instrument are simple, easy-to-make operational systems, low cost, high sensitivity and resolution.

Fiber-optical sensor with intensity compensation model in college teaching of physics experiment

NASA Astrophysics Data System (ADS)

Su, Liping; Zhang, Yang; Li, Kun; Zhang, Yu

2017-08-01

Optical fiber sensor technology is one of the main contents of modern information technology, which has a very important position in modern science and technology. Fiber optic sensor experiment can improve students' enthusiasm and broaden their horizons in college physics experiment. In this paper the main structure and working principle of fiberoptical sensor with intensity compensation model are introduced. And thus fiber-optical sensor with intensity compensation model is applied to measure micro displacement of Young's modulus measurement experiment and metal linear expansion coefficient measurement experiment in the college physics experiment. Results indicate that the measurement accuracy of micro displacement is higher than that of the traditional methods using fiber-optical sensor with intensity compensation model. Meanwhile this measurement method makes the students understand on the optical fiber, sensor and nature of micro displacement measurement method and makes each experiment strengthen relationship and compatibility, which provides a new idea for the reform of experimental teaching.

Embedded fiber optic ultrasonic sensors and generators

NASA Astrophysics Data System (ADS)

Dorighi, John F.; Krishnaswamy, Sridhar; Achenbach, Jan D.

1995-04-01

Ultrasonic sensors and generators based on fiber-optic systems are described. It is shown that intrinsic fiber optic Fabry-Perot ultrasound sensors that are embedded in a structure can be stabilized by actively tuning the laser frequency. The need for this method of stabilization is demonstrated by detecting piezoelectric transducer-generated ultrasonic pulses in the presence of low frequency dynamic strains that are intentionally induced to cause sensor drift. The actively stabilized embedded fiber optic Fabry-Perot sensor is also shown to have sufficient sensitivity to detect ultrasound that is generated in the interior of a structure by means of a high-power optical fiber that pipes energy from a pulsed laser to an embedded generator of ultrasound.

Insole optical fiber Bragg grating sensors network for dynamic vertical force monitoring

NASA Astrophysics Data System (ADS)

Domingues, Maria Fátima; Tavares, Cátia; Leitão, Cátia; Frizera-Neto, Anselmo; Alberto, Nélia; Marques, Carlos; Radwan, Ayman; Rodriguez, Jonathan; Postolache, Octavian; Rocon, Eduardo; André, Paulo; Antunes, Paulo

2017-09-01

In an era of unprecedented progress in technology and increase in population age, continuous and close monitoring of elder citizens and patients is becoming more of a necessity than a luxury. Contributing toward this field and enhancing the life quality of elder citizens and patients with disabilities, this work presents the design and implementation of a noninvasive platform and insole fiber Bragg grating sensors network to monitor the vertical ground reaction forces distribution induced in the foot plantar surface during gait and body center of mass displacements. The acquired measurements are a reliable indication of the accuracy and consistency of the proposed solution in monitoring and mapping the vertical forces active on the foot plantar sole, with a sensitivity up to 11.06 pm/N. The acquired measurements can be used to infer the foot structure and health condition, in addition to anomalies related to spine function and other pathologies (e.g., related to diabetes); also its application in rehabilitation robotics field can dramatically reduce the computational burden of exoskeletons' control strategy. The proposed technology has the advantages of optical fiber sensing (robustness, noninvasiveness, accuracy, and electromagnetic insensitivity) to surpass all drawbacks verified in traditionally used sensing systems (fragility, instability, and inconsistent feedback).

Insole optical fiber Bragg grating sensors network for dynamic vertical force monitoring.

PubMed

Domingues, Maria Fátima; Tavares, Cátia; Leitão, Cátia; Frizera-Neto, Anselmo; Alberto, Nélia; Marques, Carlos; Radwan, Ayman; Rodriguez, Jonathan; Postolache, Octavian; Rocon, Eduardo; André, Paulo; Antunes, Paulo

2017-09-01

In an era of unprecedented progress in technology and increase in population age, continuous and close monitoring of elder citizens and patients is becoming more of a necessity than a luxury. Contributing toward this field and enhancing the life quality of elder citizens and patients with disabilities, this work presents the design and implementation of a noninvasive platform and insole fiber Bragg grating sensors network to monitor the vertical ground reaction forces distribution induced in the foot plantar surface during gait and body center of mass displacements. The acquired measurements are a reliable indication of the accuracy and consistency of the proposed solution in monitoring and mapping the vertical forces active on the foot plantar sole, with a sensitivity up to 11.06 ?? pm / N . The acquired measurements can be used to infer the foot structure and health condition, in addition to anomalies related to spine function and other pathologies (e.g., related to diabetes); also its application in rehabilitation robotics field can dramatically reduce the computational burden of exoskeletons’ control strategy. The proposed technology has the advantages of optical fiber sensing (robustness, noninvasiveness, accuracy, and electromagnetic insensitivity) to surpass all drawbacks verified in traditionally used sensing systems (fragility, instability, and inconsistent feedback).

Crack Propagation Calculations for Optical Fibers under Static Bending and Tensile Loads Using Continuum Damage Mechanics

PubMed Central

Chen, Yunxia; Cui, Yuxuan; Gong, Wenjun

2017-01-01

Static fatigue behavior is the main failure mode of optical fibers applied in sensors. In this paper, a computational framework based on continuum damage mechanics (CDM) is presented to calculate the crack propagation process and failure time of optical fibers subjected to static bending and tensile loads. For this purpose, the static fatigue crack propagation in the glass core of the optical fiber is studied. Combining a finite element method (FEM), we use the continuum damage mechanics for the glass core to calculate the crack propagation path and corresponding failure time. In addition, three factors including bending radius, tensile force and optical fiber diameter are investigated to find their impacts on the crack propagation process and failure time of the optical fiber under concerned situations. Finally, experiments are conducted and the results verify the correctness of the simulation calculation. It is believed that the proposed method could give a straightforward description of the crack propagation path in the inner glass core. Additionally, the predicted crack propagation time of the optical fiber with different factors can provide effective suggestions for improving the long-term usage of optical fibers. PMID:29140284

Crack Propagation Calculations for Optical Fibers under Static Bending and Tensile Loads Using Continuum Damage Mechanics.

PubMed

Chen, Yunxia; Cui, Yuxuan; Gong, Wenjun

2017-11-15

Static fatigue behavior is the main failure mode of optical fibers applied in sensors. In this paper, a computational framework based on continuum damage mechanics (CDM) is presented to calculate the crack propagation process and failure time of optical fibers subjected to static bending and tensile loads. For this purpose, the static fatigue crack propagation in the glass core of the optical fiber is studied. Combining a finite element method (FEM), we use the continuum damage mechanics for the glass core to calculate the crack propagation path and corresponding failure time. In addition, three factors including bending radius, tensile force and optical fiber diameter are investigated to find their impacts on the crack propagation process and failure time of the optical fiber under concerned situations. Finally, experiments are conducted and the results verify the correctness of the simulation calculation. It is believed that the proposed method could give a straightforward description of the crack propagation path in the inner glass core. Additionally, the predicted crack propagation time of the optical fiber with different factors can provide effective suggestions for improving the long-term usage of optical fibers.

Improved Fiber-Optic-Coupled Pressure And Vibration Sensors

NASA Technical Reports Server (NTRS)

Zuckerwar, Allan J.; Cuomo, Frank W.

1994-01-01

Improved fiber-optic coupler enables use of single optical fiber to carry light to and from sensor head. Eliminates problem of alignment of multiple fibers in sensor head and simplifies calibration by making performance both more predictable and more stable. Sensitivities increased, sizes reduced. Provides increased margin for design of compact sensor heads not required to contain amplifier circuits and withstand high operating temperatures.

Distributed Fiber-Optic Sensors for Vibration Detection

PubMed Central

Liu, Xin; Jin, Baoquan; Bai, Qing; Wang, Yu; Wang, Dong; Wang, Yuncai

2016-01-01

Distributed fiber-optic vibration sensors receive extensive investigation and play a significant role in the sensor panorama. Optical parameters such as light intensity, phase, polarization state, or light frequency will change when external vibration is applied on the sensing fiber. In this paper, various technologies of distributed fiber-optic vibration sensing are reviewed, from interferometric sensing technology, such as Sagnac, Mach–Zehnder, and Michelson, to backscattering-based sensing technology, such as phase-sensitive optical time domain reflectometer, polarization-optical time domain reflectometer, optical frequency domain reflectometer, as well as some combinations of interferometric and backscattering-based techniques. Their operation principles are presented and recent research efforts are also included. Finally, the applications of distributed fiber-optic vibration sensors are summarized, which mainly include structural health monitoring and perimeter security, etc. Overall, distributed fiber-optic vibration sensors possess the advantages of large-scale monitoring, good concealment, excellent flexibility, and immunity to electromagnetic interference, and thus show considerable potential for a variety of practical applications. PMID:27472334

Distributed Fiber-Optic Sensors for Vibration Detection.

PubMed

Liu, Xin; Jin, Baoquan; Bai, Qing; Wang, Yu; Wang, Dong; Wang, Yuncai

2016-07-26

Distributed fiber-optic vibration sensors receive extensive investigation and play a significant role in the sensor panorama. Optical parameters such as light intensity, phase, polarization state, or light frequency will change when external vibration is applied on the sensing fiber. In this paper, various technologies of distributed fiber-optic vibration sensing are reviewed, from interferometric sensing technology, such as Sagnac, Mach-Zehnder, and Michelson, to backscattering-based sensing technology, such as phase-sensitive optical time domain reflectometer, polarization-optical time domain reflectometer, optical frequency domain reflectometer, as well as some combinations of interferometric and backscattering-based techniques. Their operation principles are presented and recent research efforts are also included. Finally, the applications of distributed fiber-optic vibration sensors are summarized, which mainly include structural health monitoring and perimeter security, etc. Overall, distributed fiber-optic vibration sensors possess the advantages of large-scale monitoring, good concealment, excellent flexibility, and immunity to electromagnetic interference, and thus show considerable potential for a variety of practical applications.

Single Particle Differentiation through 2D Optical Fiber Trapping and Back-Scattered Signal Statistical Analysis: An Exploratory Approach

PubMed Central

Ribeiro, Rita S. R.; Cunha, João P. S.; Rosa, Carla C.; Jorge, Pedro A. S.

2018-01-01

Recent trends on microbiology point out the urge to develop optical micro-tools with multifunctionalities such as simultaneous manipulation and sensing. Considering that miniaturization has been recognized as one of the most important paradigms of emerging sensing biotechnologies, optical fiber tools, including Optical Fiber Tweezers (OFTs), are suitable candidates for developing multifunctional small sensors for Medicine and Biology. OFTs are flexible and versatile optotools based on fibers with one extremity patterned to form a micro-lens. These are able to focus laser beams and exert forces onto microparticles strong enough (piconewtons) to trap and manipulate them. In this paper, through an exploratory analysis of a 45 features set, including time and frequency-domain parameters of the back-scattered signal of particles trapped by a polymeric lens, we created a novel single feature able to differentiate synthetic particles (PMMA and Polystyrene) from living yeasts cells. This single statistical feature can be useful for the development of label-free hybrid optical fiber sensors with applications in infectious diseases detection or cells sorting. It can also contribute, by revealing the most significant information that can be extracted from the scattered signal, to the development of a simpler method for particles characterization (in terms of composition, heterogeneity degree) than existent technologies. PMID:29495502

Single Particle Differentiation through 2D Optical Fiber Trapping and Back-Scattered Signal Statistical Analysis: An Exploratory Approach.

PubMed

Paiva, Joana S; Ribeiro, Rita S R; Cunha, João P S; Rosa, Carla C; Jorge, Pedro A S

2018-02-27

Recent trends on microbiology point out the urge to develop optical micro-tools with multifunctionalities such as simultaneous manipulation and sensing. Considering that miniaturization has been recognized as one of the most important paradigms of emerging sensing biotechnologies, optical fiber tools, including Optical Fiber Tweezers (OFTs), are suitable candidates for developing multifunctional small sensors for Medicine and Biology. OFTs are flexible and versatile optotools based on fibers with one extremity patterned to form a micro-lens. These are able to focus laser beams and exert forces onto microparticles strong enough (piconewtons) to trap and manipulate them. In this paper, through an exploratory analysis of a 45 features set, including time and frequency-domain parameters of the back-scattered signal of particles trapped by a polymeric lens, we created a novel single feature able to differentiate synthetic particles (PMMA and Polystyrene) from living yeasts cells. This single statistical feature can be useful for the development of label-free hybrid optical fiber sensors with applications in infectious diseases detection or cells sorting. It can also contribute, by revealing the most significant information that can be extracted from the scattered signal, to the development of a simpler method for particles characterization (in terms of composition, heterogeneity degree) than existent technologies.

Downhole geothermal well sensors comprising a hydrogen-resistant optical fiber

DOEpatents

Weiss, Jonathan D.

2005-02-08

A new class of optical fiber based thermal sensors has been invented. The new sensors comprise hydrogen-resistant optical fibers which are able to withstand a hot, hydrogen-containing environment as is often found in the downhole well environment.

Fiber-Optic/Photoelastic Flow Sensors

NASA Technical Reports Server (NTRS)

Wesson, Laurence N.; Cabato, Nellie L.; Brooks, Edward F.

1995-01-01

Simple, rugged, lightweight transducers detect periodic vortices. Fiber-optic-coupled transducers developed to measure flows over wide dynamic ranges and over wide temperature ranges in severe environments. Used to measure flows of fuel in advanced aircraft engines. Feasibility of sensors demonstrated in tests of prototype sensor in water flowing at various temperatures and speeds. Particularly attractive for aircraft applications because optical fibers compact and make possible transmission of sensor signals at high rates with immunity from electromagnetic interference at suboptical frequencies. Sensors utilize optical-to-optical conversion via photoelastic effect.

Optical fiber sensors for materials and structures characterization

NASA Technical Reports Server (NTRS)

Lindner, D. K.; Claus, R. O.

1991-01-01

The final technical report on Optical Fiber Sensors for Materials and Structures Characterization, covering the period August 1990 through August 1991 is presented. Research programs in the following technical areas are described; sapphire optical fiber sensors; vibration analysis using two-mode elliptical core fibers and sensors; extrinsic Fabry-Perot interferometer development; and coatings for fluorescent-based sensor. Research progress in each of these areas was substantial, as evidenced by the technical publications which are included as appendices.

Tapered Optical Fiber Functionalized with Palladium Nanoparticles by Drop Casting and Laser Radiation for H2 and Volatile Organic Compounds Sensing Purposes

PubMed Central

González-Sierra, Nancy Elizabeth; Gómez-Pavón, Luz del Carmen; Pérez-Sánchez, Gerardo Francisco; Luis-Ramos, Arnulfo; Zaca-Morán, Plácido; Chávez-Ramírez, Fernando

2017-01-01

A comparative study on the sensing properties of a tapered optical fiber pristine and functionalized with the palladium nanoparticles to hydrogen and volatile organic compounds (VOCs), is presented. The sensor response and, response/recovery times were extracted from the measurements of the transient response of the device. The tapered optical fiber sensor was fabricated using a single-mode optical fiber by the flame-brushing technique. Functionalization of the optical fiber was performed using an aqueous solution of palladium chloride by drop-casting technique assisted for laser radiation. The detection principle of the sensor is based on the changes in the optical properties of palladium nanoparticles when exposed to reducing gases, which causes a variation in the absorption of evanescent waves. A continuous wave laser diode operating at 1550 nm is used for the sensor characterization. The sensor functionalized with palladium nanoparticles by this technique is viable for the sensing of hydrogen and VOCs, since it shows an enhancement in sensor response and response time compared to the sensor based on the pristine optical microfiber. The results show that the fabricated sensor is competitive with other fiber optic sensors functionalized with palladium nanoparticles to the hydrogen. PMID:28878161

Tapered Optical Fiber Functionalized with Palladium Nanoparticles by Drop Casting and Laser Radiation for H₂ and Volatile Organic Compounds Sensing Purposes.

PubMed

González-Sierra, Nancy Elizabeth; Gómez-Pavón, Luz Del Carmen; Pérez-Sánchez, Gerardo Francisco; Luis-Ramos, Arnulfo; Zaca-Morán, Plácido; Muñoz-Pacheco, Jesús Manuel; Chávez-Ramírez, Francisco

2017-09-06

A comparative study on the sensing properties of a tapered optical fiber pristine and functionalized with the palladium nanoparticles to hydrogen and volatile organic compounds (VOCs), is presented. The sensor response and, response/recovery times were extracted from the measurements of the transient response of the device. The tapered optical fiber sensor was fabricated using a single-mode optical fiber by the flame-brushing technique. Functionalization of the optical fiber was performed using an aqueous solution of palladium chloride by drop-casting technique assisted for laser radiation. The detection principle of the sensor is based on the changes in the optical properties of palladium nanoparticles when exposed to reducing gases, which causes a variation in the absorption of evanescent waves. A continuous wave laser diode operating at 1550 nm is used for the sensor characterization. The sensor functionalized with palladium nanoparticles by this technique is viable for the sensing of hydrogen and VOCs, since it shows an enhancement in sensor response and response time compared to the sensor based on the pristine optical microfiber. The results show that the fabricated sensor is competitive with other fiber optic sensors functionalized with palladium nanoparticles to the hydrogen.

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

NASA Astrophysics Data System (ADS)

Liu, Yuxiang

2011-12-01

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.

Microwave assisted reconstruction of optical interferograms for distributed fiber optic sensing.

PubMed

Huang, Jie; Hua, Lei; Lan, Xinwei; Wei, Tao; Xiao, Hai

2013-07-29

This paper reports a distributed fiber optic sensing technique through microwave assisted separation and reconstruction of optical interferograms in spectrum domain. The approach involves sending a microwave-modulated optical signal through cascaded fiber optic interferometers. The microwave signal was used to resolve the position and reflectivity of each sensor along the optical fiber. By sweeping the optical wavelength and detecting the modulation signal, the optical spectrum of each sensor can be reconstructed. Three cascaded fiber optic extrinsic Fabry-Perot interferometric sensors were used to prove the concept. Their microwave-reconstructed interferogram matched well with those recorded individually using an optical spectrum analyzer. The application in distributed strain measurement has also been demonstrated.

Sensitive Detection of Small Particles in Fluids Using Optical Fiber Tip with Dielectrophoresis

PubMed Central

Tai, Yi-Hsin; Chang, Dao-Ming; Pan, Ming-Yang; Huang, Ding-Wei; Wei, Pei-Kuen

2016-01-01

This work presents using a tapered fiber tip coated with thin metallic film to detect small particles in water with high sensitivity. When an AC voltage applied to the Ti/Al coated fiber tip and indium tin oxide (ITO) substrate, a gradient electric field at the fiber tip induced attractive/repulsive force to suspended small particles due to the frequency-dependent dielectrophoresis (DEP) effect. Such DEP force greatly enhanced the concentration of the small particles near the tip. The increase of the local concentration also increased the scattering of surface plasmon wave near the fiber tip. Combined both DEP effect and scattering optical near-field, we show the detection limit of the concentration for 1.36 μm polystyrene beads can be down to 1 particle/mL. The detection limit of the Escherichia coli (E. coli) bacteria was 20 CFU/mL. The fiber tip sensor takes advantages of ultrasmall volume, label-free and simple detection system. PMID:26927128

Chemical, biochemical, and environmental fiber sensors IV; Proceedings of the Meeting, Boston, MA, Sept. 8, 9, 1992

NASA Astrophysics Data System (ADS)

Lieberman, Robert A.

Various paper on chemical, biochemical, and environmental fiber sensors are presented. Some of the individual topics addressed include: evanescent-wave fiber optic (FO) biosensor, refractive-index sensors based on coupling to high-index multimode overlays, advanced technique in FO sensors, design of luminescence-based temperature sensors, NIR fluorescence in FO applications, FO sensor based on microencapsulated reagents, emitters and detectors for optical gas and chemical sensing, tunable fiber laser source for methane detection at 1.68 micron, FO fluorometer based on a dual-wavelength laser excitation source, thin polymer films as active components of FO chemical sensors, submicron optical sources for single macromolecule detection, nanometer optical fiber pH sensor. Also discussed are: microfabrication of optical sensor array, luminescent FO sensor for the measurement of pH, time-domain fluorescence methods as applied to pH sensing, characterization of a sol-gel-entrapped artificial receptor, FO technology for nuclear waste cleanup, spectroscopic gas sensing with IR hollow waveguides, dissolved-oxygen quenching of in situ fluorescence measurements.

Fiber optic controls for aircraft engines - Issues and implications

NASA Technical Reports Server (NTRS)

Dasgupta, Samhita; Poppel, Gary L.; Anderson, William P.

1991-01-01

Some of the issues involved with the application of fiber-optic controls for aircraft engines in the harsh operating environment are addressed, with emphasis on fiber-optic temperature, pressure, position, and speed sensors. Criteria are established to evaluate the optical modulation technique, the sensor/control unit interconnection, and the electrooptic architecture. Single mode and polarization dependent sensor types, sensors which depend on the reflection and/or transmission of light through the engine environment, and intensity-based analog sensors are eliminated as a possible candidate for engine implementation. Fiber-optic harnesses tested for their optical integrity, temperature stability, and mechanical strength, exhibit a capacity to meet mechanical strength requirements and still gain a significant reduction in cable weight.

Single mode variable-sensitivity fiber optic sensors

NASA Technical Reports Server (NTRS)

Murphy, K. A.; Fogg, B. R.; Gunther, M. F.; Claus, R. O.

1992-01-01

We review spatially-weighted optical fiber sensors that filter specific vibration modes from one dimensional beams placed in clamped-free and clamped-clamped configurations. The sensitivity of the sensor is varied along the length of the fiber by tapering circular-core, dual-mode optical fibers. Selective vibration mode suppression on the order of 10 dB was obtained. We describe experimental results and propose future extensions to single mode sensor applications.

Single- and two-phase flow characterization using optical fiber bragg gratings.

PubMed

Baroncini, Virgínia H V; Martelli, Cicero; da Silva, Marco José; Morales, Rigoberto E M

2015-03-17

Single- and two-phase flow characterization using optical fiber Bragg gratings (FBGs) is presented. The sensor unit consists of the optical fiber Bragg grating positioned transversely to the flow and fixed in the pipe walls. The hydrodynamic pressure applied by the liquid or air/liquid flow to the optical fiber induces deformation that can be detected by the FBG. Given that the applied pressure is directly related to the mass flow, it is possible to establish a relationship using the grating resonance wavelength shift to determine the mass flow when the flow velocity is well known. For two phase flows of air and liquid, there is a significant change in the force applied to the fiber that accounts for the very distinct densities of these substances. As a consequence, the optical fiber deformation and the correspondent grating wavelength shift as a function of the flow will be very different for an air bubble or a liquid slug, allowing their detection as they flow through the pipe. A quasi-distributed sensing tool with 18 sensors evenly spread along the pipe is developed and characterized, making possible the characterization of the flow, as well as the tracking of the bubbles over a large section of the test bed. Results show good agreement with standard measurement methods and open up plenty of opportunities to both laboratory measurement tools and field applications.

A novel integrated multifunction micro-sensor for three-dimensional micro-force measurements.

PubMed

Wang, Weizhong; Zhao, Yulong; Qin, Yafei

2012-01-01

An integrated multifunction micro-sensor for three-dimensional micro-force precision measurement under different pressure and temperature conditions is introduced in this paper. The integrated sensor consists of three kinds of sensors: a three-dimensional micro-force sensor, an absolute pressure sensor and a temperature sensor. The integrated multifunction micro-sensor is fabricated on silicon wafers by micromachining technology. Different doping doses of boron ion, placement and structure of resistors are tested for the force sensor, pressure sensor and temperature sensor to minimize the cross interference and optimize the properties. A glass optical fiber, with a ladder structure and sharp tip etched by buffer oxide etch solution, is glued on the micro-force sensor chip as the tactile probe. Experimental results show that the minimum force that can be detected by the force sensor is 300 nN; the lateral sensitivity of the force sensor is 0.4582 mV/μN; the probe length is linearly proportional to sensitivity of the micro-force sensor in lateral; the sensitivity of the pressure sensor is 0.11 mv/KPa; the sensitivity of the temperature sensor is 5.836 × 10(-3) KΩ/°C. Thus it is a cost-effective method to fabricate integrated multifunction micro-sensors with different measurement ranges that could be used in many fields.

Highly Sensitive Temperature Sensors Based on Fiber-Optic PWM and Capacitance Variation Using Thermochromic Sensing Membrane.

PubMed

Khan, Md Rajibur Rahaman; Kang, Shin-Won

2016-07-09

In this paper, we propose a temperature/thermal sensor that contains a Rhodamine-B sensing membrane. We applied two different sensing methods, namely, fiber-optic pulse width modulation (PWM) and an interdigitated capacitor (IDC)-based temperature sensor to measure the temperature from 5 °C to 100 °C. To the best of our knowledge, the fiber-optic PWM-based temperature sensor is reported for the first time in this study. The proposed fiber-optic PWM temperature sensor has good sensing ability; its sensitivity is ~3.733 mV/°C. The designed temperature-sensing system offers stable sensing responses over a wide dynamic range, good reproducibility properties with a relative standard deviation (RSD) of ~0.021, and the capacity for a linear sensing response with a correlation coefficient of R² ≈ 0.992 over a wide sensing range. In our study, we also developed an IDC temperature sensor that is based on the capacitance variation principle as the IDC sensing element is heated. We compared the performance of the proposed temperature-sensing systems with different fiber-optic temperature sensors (which are based on the fiber-optic wavelength shift method, the long grating fiber-optic Sagnac loop, and probe type fiber-optics) in terms of sensitivity, dynamic range, and linearity. We observed that the proposed sensing systems have better sensing performance than the above-mentioned sensing system.

Testing of Sapphire Optical Fiber and Sensors in Intense Radiation Fields When Subjected to Very High Temperatures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Blue, Thomas; Windl, Wolfgang

The primary objective of this project was to determine the optical attenuation and signal degradation of sapphire optical fibers & sensors (temperature & strain), in-situ, operating at temperatures up to 1500°C during reactor irradiation through experiments and modeling. The results will determine the feasibility of extending sapphire optical fiber-based instrumentation to extremely high temperature radiation environments. This research will pave the way for future testing of sapphire optical fibers and fiber-based sensors under conditions expected in advanced high temperature reactors.

Optical Fiber-Tip Sensors Based on In-Situ µ-Printed Polymer Suspended-Microbeams.

PubMed

Yao, Mian; Ouyang, Xia; Wu, Jushuai; Zhang, A Ping; Tam, Hwa-Yaw; Wai, P K A

2018-06-05

Miniature optical fiber-tip sensors based on directly µ-printed polymer suspended-microbeams are presented. With an in-house optical 3D μ-printing technology, SU-8 suspended-microbeams are fabricated in situ to form Fabry⁻Pérot (FP) micro-interferometers on the end face of standard single-mode optical fiber. Optical reflection spectra of the fabricated FP micro-interferometers are measured and fast Fourier transform is applied to analyze the cavity of micro-interferometers. The applications of the optical fiber-tip sensors for refractive index (RI) sensing and pressure sensing, which showed 917.3 nm/RIU to RI change and 4.29 nm/MPa to pressure change, respectively, are demonstrated in the experiments. The sensors and their optical µ-printing method unveil a new strategy to integrate complicated microcomponents on optical fibers toward 'lab-on-fiber' devices and applications.

Comparison of sensitivity and resolution load sensor at various configuration polymer optical fiber

NASA Astrophysics Data System (ADS)

Arifin, A.; Yusran, Miftahuddin, Abdullah, Bualkar; Tahir, Dahlang

2017-01-01

This study uses a load sensor with a macro-bending on polymer optical fiber loop model which is placed between two plates with a buffer spring. The load sensor with light intensity modulation principle is an infrared LED emits light through the polymer optical fiber then received by the phototransistor and amplifier. Output voltage from the amplifier continued to arduino sequence and displayed on the computer. Load augment on the sensor resulted in an increase of curvature on polymer optical fibers that can cause power losses gets bigger too. This matter will result in the intensity of light that received by phototransistor getting smaller, so that the output voltage that ligable on computer will be getting smaller too. The sensitivity and resolution load sensors analyzed based on configuration with various amount of loops, imperfection on the jacket, and imperfection at the cladding and core of polymer optical fiber. The results showed that the augment on the amount of load, imperfection on the jacket and imperfection on the sheath and core polymer optical fiber can improve the sensitivity and resolution of the load sensor. The best sensors resolution obtained on the number of loops 4 with imperfection 8 on the core and cladding polymer optical fiber that is 0.037 V/N and 0,026 N. The advantages of the load sensor based on polymers optical fiber are easy to make, low cost and simple to use measurement methods.

Development and evaluation of fiber optic sensors : final report.

DOT National Transportation Integrated Search

2003-05-01

This study investigated the feasibility of using fiber optic sensors to capture traffic data. Funding from the : study was used to develop a prototype sensor using fiber Bragg gratings (FBG) technology. The sensor was : tested on a high volume portla...

Graphene enhanced optical fiber SPR sensor for liquid concentration measurement

NASA Astrophysics Data System (ADS)

Zhou, Xue; Li, Xuegang; Cheng, TongLei; Li, Shuguang; An, Guowen

2018-07-01

A high sensitivity optical fiber Surface Plasmon Resonance (SPR) sensor which based on coreless optical fiber, silver film and graphene, has been designed and implemented for liquid concentration detection. In this paper, Graphene is firstly verified that it can be used to enhance the evanescent field of traditional optical fiber and thus increasing sensitivity in experiment. The sensitivity of proposed sensor is 6.417 nm/%, which is higher than that of the traditional optical fiber SPR sensor according to the comparative experiments. In addition, the proposed sensor is extremely easy to make and the silver film could be protected from oxidation and damage due to the existence of graphene. Moreover, the sensor has pretty small size, immunity to electromagnetic interference, quick response speed and thus can suitable a variety of severe environments and real-time measurement.

Spectrum-Modulating Fiber-Optic Sensors

NASA Technical Reports Server (NTRS)

Beheim, Glenn; Fritsch, Klaus

1989-01-01

Family of spectrum-modulating fiber-optic sensors undergoing development for use in aircraft-engine control systems. Fiber-optic sensors offer advantages of small size, high bandwidth, immunity to electromagnetic interference, and light weight. Furthermore, they reduce number of locations on aircraft to which electrical power has to be supplied.

Recent Developments in Fiber Optics Humidity Sensors.

PubMed

Ascorbe, Joaquin; Corres, Jesus M; Arregui, Francisco J; Matias, Ignacio R

2017-04-19

A wide range of applications such as health, human comfort, agriculture, food processing and storage, and electronic manufacturing, among others, require fast and accurate measurement of humidity. Sensors based on optical fibers present several advantages over electronic sensors and great research efforts have been made in recent years in this field. The present paper reports the current trends of optical fiber humidity sensors. The evolution of optical structures developed towards humidity sensing, as well as the novel materials used for this purpose, will be analyzed. Well-known optical structures, such as long-period fiber gratings or fiber Bragg gratings, are still being studied towards an enhancement of their sensitivity. Sensors based on lossy mode resonances constitute a platform that combines high sensitivity with low complexity, both in terms of their fabrication process and the equipment required. Novel structures, such as resonators, are being studied in order to improve the resolution of humidity sensors. Moreover, recent research on polymer optical fibers suggests that the sensitivity of this kind of sensor has not yet reached its limit. Therefore, there is still room for improvement in terms of sensitivity and resolution.

Recent Developments in Fiber Optics Humidity Sensors

PubMed Central

Ascorbe, Joaquin; Corres, Jesus M.; Arregui, Francisco J.; Matias, Ignacio R.

2017-01-01

A wide range of applications such as health, human comfort, agriculture, food processing and storage, and electronic manufacturing, among others, require fast and accurate measurement of humidity. Sensors based on optical fibers present several advantages over electronic sensors and great research efforts have been made in recent years in this field. The present paper reports the current trends of optical fiber humidity sensors. The evolution of optical structures developed towards humidity sensing, as well as the novel materials used for this purpose, will be analyzed. Well-known optical structures, such as long-period fiber gratings or fiber Bragg gratings, are still being studied towards an enhancement of their sensitivity. Sensors based on lossy mode resonances constitute a platform that combines high sensitivity with low complexity, both in terms of their fabrication process and the equipment required. Novel structures, such as resonators, are being studied in order to improve the resolution of humidity sensors. Moreover, recent research on polymer optical fibers suggests that the sensitivity of this kind of sensor has not yet reached its limit. Therefore, there is still room for improvement in terms of sensitivity and resolution. PMID:28422074

Fiber Optic Temperature Sensors in TPS: Arc Jet Model Design & Testing

NASA Technical Reports Server (NTRS)

Black, Richard; Feldman, Jay; Ellerby, Donald; Monk, Joshua; Moslehi, Behzad; Oblea, Levy; Switzer, Matthew

2017-01-01

Techniques for using fiber optics with Fiber Bragg Gratings (FBGs) have been developed by IFOS Corp. for use in thermal protection systems (TPS) on spacecraft heat shield materials through NASA Phase 1 and 2 SBIR efforts and have been further improved in a recent collaboration between IFOS and NASA that will be described here. Fiber optic temperature sensors offer several potential advantages over traditional thermocouple sensors including a) multiplexing many sensors in a single fiber to increase sensor density in a given array or to provide spatial resolution, b) improved thermal property match between sensor and TPS to reduce heat flow disruption, c) lack of electrical conductivity.

Loss-compensation technique using a split-spectrum approach for optical fiber air-gap intensity-based sensors

NASA Astrophysics Data System (ADS)

Wang, Anbo; Miller, Mark S.; Gunther, Michael F.; Murphy, Kent A.; Claus, Richard O.

1993-03-01

A self-referencing technique compensating for fiber losses and source fluctuations in air-gap intensity-based optical fiber sensors is described and demonstrated. A resolution of 0.007 micron has been obtained over a measurement range of 0-250 microns for an intensity-based displacement sensor using this referencing technique. The sensor is shown to have minimal sensitivity to fiber bending losses and variations in the LED input power. A theoretical model for evaluation of step-index multimode optical fiber splice is proposed. The performance of the sensor as a displacement sensor agrees well with the theoretical analysis.

Optical fiber sensors embedded in flexible polymer foils

NASA Astrophysics Data System (ADS)

van Hoe, Bram; van Steenberge, Geert; Bosman, Erwin; Missinne, Jeroen; Geernaert, Thomas; Berghmans, Francis; Webb, David; van Daele, Peter

2010-04-01

In traditional electrical sensing applications, multiplexing and interconnecting the different sensing elements is a major challenge. Recently, many optical alternatives have been investigated including optical fiber sensors of which the sensing elements consist of fiber Bragg gratings. Different sensing points can be integrated in one optical fiber solving the interconnection problem and avoiding any electromagnetical interference (EMI). Many new sensing applications also require flexible or stretchable sensing foils which can be attached to or wrapped around irregularly shaped objects such as robot fingers and car bumpers or which can even be applied in biomedical applications where a sensor is fixed on a human body. The use of these optical sensors however always implies the use of a light-source, detectors and electronic circuitry to be coupled and integrated with these sensors. The coupling of these fibers with these light sources and detectors is a critical packaging problem and as it is well-known the costs for packaging, especially with optoelectronic components and fiber alignment issues are huge. The end goal of this embedded sensor is to create a flexible optical sensor integrated with (opto)electronic modules and control circuitry. To obtain this flexibility, one can embed the optical sensors and the driving optoelectronics in a stretchable polymer host material. In this article different embedding techniques for optical fiber sensors are described and characterized. Initial tests based on standard manufacturing processes such as molding and laser structuring are reported as well as a more advanced embedding technique based on soft lithography processing.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shiquan Tao

2006-12-31

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 fibermore » 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.« less

An Optical Fiber Sensor and Its Application in UAVs for Current Measurements

PubMed Central

Delgado, Felipe S.; Carvalho, João P.; Coelho, Thiago V. N.; Dos Santos, Alexandre B.

2016-01-01

In this paper, we propose and experimentally investigate an optical sensor based on a novel combination of a long-period fiber grating (LPFG) with a permanent magnet to measure electrical current in unmanned aerial vehicles (UAVs). The proposed device uses a neodymium magnet attached to the grating structure, which suffers from an electromagnetic force produced when the current flows in the wire of the UAV engine. Therefore, it causes deformation on the sensor and thus, different shifts occur in the resonant bands of the transmission spectrum of the LPFG. Finally, the results show that it is possible to monitor electrical current throughout the entire operating range of the UAV engine from 0 A to 10 A in an effective and practical way with good linearity, reliability and response time, which are desirable characteristics in electrical current sensing. PMID:27801798

Plastic optical fiber level measurement sensor based on side holes

NASA Astrophysics Data System (ADS)

Park, Young June; Shin, Jong-Dug; Park, Jaehee

2014-10-01

Plastic optical fiber level measurement sensor based on in-line side holes is investigated theoretically and experimentally. The sensor consists of a plastic optical fiber with in-line side holes spaced about 5 cm apart. The 0.9 diameter in-line side holes were fabricated by micro-drilling. An analytical expression of the sensor transmittance was obtained using a simple ray optics approach. The measurements of the sensor transmittance were performed with a 55 cm height Mass cylinder. Both results show that the sensor transmittance increases as the number of side holes filled with water increases. The research results indicate that the plastic optical fiber based on in-line side holes can be used for water level measurement.

Non-enzymatic glucose detection based on phenylboronic acid modified optical fibers

NASA Astrophysics Data System (ADS)

Sun, Xiaolan; Li, Nana; Zhou, Bin; Zhao, Wei; Liu, Liyuan; Huang, Chao; Ma, Longfei; Kost, Alan R.

2018-06-01

A non-enzymatic, sensitive glucose sensor was fabricated based on an evanescent wave absorbing optical fiber probe. The optical fiber sensor was functionalized by fixing a poly (phenylboronic acid) (polyPBA) film onto the conical region of the single mode fiber. The reflected light intensity of the polyPBA-functionalized fiber sensor increased proportionally with glucose concentration in the range of 0-60 mM, and the sensor showed good reproducibility and stability. The developed sensor possessed a high sensitivity of 0.1787%/mM and good linearity. The measurement of glucose concentration in human serum was also demonstrated.

High-temperature fiber optic pressure sensor

NASA Technical Reports Server (NTRS)

Berthold, J. W.

1984-01-01

Attention is given to a program to develop fiber optic methods to measure diaphragm deflection. The end application is intended for pressure transducers capable of operating to 540 C. In this paper are reported the results of a laboratory study to characterize the performance of the fiber-optic microbend sensor. The data presented include sensitivity and spring constant. The advantages and limitations of the microbend sensor for static pressure measurement applications are described. A proposed design is presented for a 540 C pressure transducer using the fiber optic microbend sensor.

A hetero-core fiber optic smart mat sensor for discrimination between a moving human and object on temporal loss peaks

NASA Astrophysics Data System (ADS)

Hosoki, Ai; Nishiyama, Michiko; Choi, Yongwoon; Watanabe, Kazuhiro

2011-05-01

In this paper, we propose discrimination method between a moving human and object by means of a hetero-core fiber smart mat sensor which induces the optical loss change in time. In addition to several advantages such as flexibility, thin size and resistance to electro-magnetic interference for a fiber optic sensor, a hetero-core fiber optic sensor is sensitive to bending action of the sensor portion and independent of temperature fluctuations. Therefore, the hetero-core fiber thin mat sensor can have a fewer sensing portions than the conventional floor pressure sensors, furthermore, can detect the wide area covering the length of strides. The experimental results for human walking tests showed that the mat sensors were reproducibly working in real-time under limiting locations the foot passed in the mat sensor. Focusing on the temporal peak numbers in the optical loss, human walking and wheeled platform moving action induced the peak numbers in the range of 1 - 3 and 5 - 7, respectively, for the 10 persons including 9 male and 1 female. As a result, we conclude that the hetero-core fiber mat sensor is capable of discriminating between the moving human and object such as a wheeled platform focusing on the peak numbers in the temporal optical loss.

Quasi-distributed sol-gel coated fiber optic oxygen sensing probe

NASA Astrophysics Data System (ADS)

Zolkapli, Maizatul; Saharudin, Suhairi; Herman, Sukreen Hana; Abdullah, Wan Fazlida Hanim

2018-03-01

In the field of aquaculture, optical sensor technology is beginning to provide alternatives to the conventional electrical sensor. Hence, the development and characterization of a multipoint quasi-distributed optical fiber sensor for oxygen measurement is reported. The system is based on 1 mm core diameter plastic optical fiber where sections of cladding have been removed and replaced with three metal complexes sol-gel films to form sensing points. The sensing locations utilize luminophores that have emission peaks at 385 nm, 405 nm and 465 nm which associated with each of the sensing points. Interrogation of the optical sensor system is through a fiber optic spectrometer incorporating narrow bandpass emission optical filter. The sensors showed comparable sensitivity and repeatability, as well as fast response and recovery towards oxygen.

Development of an instrumentation system for measurement of degradation of lubricating oil using optical fiber sensor

NASA Astrophysics Data System (ADS)

Laskar, S.; Bordoloi, S.

2016-01-01

This paper presents an instrumentation system to measure the degradation in lubricating oil using a bare, tapered and bent multi-mode optical fiber (BTBMOF) sensor probe and a temperature probe. The sensor system consists of (i) a bare, tapered and bent multi-mode optical fiber (BTBMOF) as optical sensor along with a laser source and a LDR (Light Dependent Resistor) as detector (ii) a temperature sensor (iii) a ATmega microcontroller based data acquisition system and (iv) a trained ANN for processing and calibration. The BTBMOF sensor and the temperature sensor are used to provide the measure of refractive index (RI) and the temperature of a lubricating oil sample. A microcontroller based instrumentation system with trained ANN algorithm has been developed to determine the degradation of the lubricating oil sample by sampling the readings of the optical fiber sensor, and the temperature sensor.

A comprehensive review of lossy mode resonance-based fiber optic sensors

NASA Astrophysics Data System (ADS)

Wang, Qi; Zhao, Wan-Ming

2018-01-01

This review paper presents the achievements and present developments in lossy mode resonances-based optical fiber sensors in different sensing field, such as physical, chemical and biological, and briefly look forward to its future development trend in the eyes of the author. Lossy mode resonances (LMR) is a relatively new physical optics phenomenon put forward in recent years. Fiber sensors utilizing LMR offered a new way to improve the sensing capability. LMR fiber sensors have diverse structures such as D-shaped, cladding-off, fiber tip, U-shaped and tapered fiber structures. Major applications of LMR sensors include refraction sensors and biosensors. LMR-based fiber sensors have attracted considerable research and development interest, because of their distinct advantages such as high sensitivity and label-free measurement. This kind of sensor is also of academic interest and many novel and great ideas are continuously developed.

Fiber-optic interferometric sensors for measurements of pressure fluctuations - Experimental evaluation

NASA Technical Reports Server (NTRS)

Cho, Y. C.; Soderman, P. T.

1993-01-01

A fiber optic interferometric sensor that is being developed at NASA Ames Research Center for pressure fluctuation measurements in wind tunnels is considered. Preliminary evaluation indicates that the fiber optic interferometric sensor can be successfully used as an aeroacoustic sensor and is capable of providing a powerful instrument to solve complex acoustic measurement problems in wind tunnels.

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

PubMed Central

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

2014-01-01

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

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

PubMed

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

2014-01-01

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.

photonic sensors review progress of optical fiber sensors and its application in harsh environment

NASA Astrophysics Data System (ADS)

Zhang, Min; Ma, Xiaohong; Wang, Liwei; Lai, Shurong; Zhou, Hongpu; Zhao, Huafeng; Liao, Yanbiao

2011-03-01

Fiber sensors have been developed for industry application with significant advantages. In this paper, Fiber sensors for oil field service and harsh environment monitoring which have been investigated in Tsinghua University are demonstrated. By discussing the requirements of practical applications, the key technologies of long-period fiber grating (LPFG) based fiber sensor, optical spectrum analyzer for oil detection, laser induced breakdown spectroscopy (LIBS) system for soil contamination monitoring, and seismic sensor arrays are described.

Noncontacting Optical Measurement And Inspection Systems

NASA Astrophysics Data System (ADS)

Asher, Jeffrey A.; Jackson, Robert L.

1986-10-01

Product inspection continues to play a growing role in the improvement of quality and reduction of scrap. Recent emphasis on precision measurements and in-process inspection have been a driving force for the development of noncontacting sensors. Noncontacting sensors can provide long term, unattended use due to the lack of sensor wear. Further, in applications where, sensor contact can damage or geometrically change the part to be measured or inspected, noncontacting sensors are the only technical approach available. MTI is involved in the development and sale of noncontacting sensors and custom inspection systems. This paper will review the recent advances in noncontacting sensor development. Machine vision and fiber optics sensor systems are finding a wide variety of industrial inspection applications. This paper will provide detailed examples of several state-of-the-art applications for these noncontacting sensors.

Polarization maintaining fiber magnetic sensor based on the digital phase generated carrier technology

NASA Astrophysics Data System (ADS)

Zhang, Xueliang; Meng, Zhou; Hu, Zhengliang; Yang, Huayong; Song, Zhangqi; Hu, Yongming

2008-12-01

A polarization maintaining fiber (PMF) magnetic field sensor based on a digital phase generated carrier (PGC) technology is presented. A magnetic sensor constructed with two magnetostrictive strips attached on the sensing fiber is joined in the sensing arm of a fiber Michelson interferometer. The fiber optic interferometric system is made of all PMF, which inhibits the polarization-induced signal fading. The light source is a fiber laser which can be modulated directly. The PGC metnod is used to demodulate magnetic field signal avoiding phase induced interferometric signal fading, and ensure the sensing partto be all fiber structure. A fiber optic magnetic field sensor with appreciate size for the fiber optic hydrophone towed array is obtained, which can be used to sense the enviromental magnetic field along the sensing direction.This sensor is a good choice for the directional angle measurement through sensing the Earth magnetic field in the array shape measurement of a fiber optic hydrophone towed array.

Fiber optic chloride sensing: if corrosion's the problem, chloride sensing is the key

NASA Astrophysics Data System (ADS)

Fuhr, Peter L.; MacCraith, Brian D.; Huston, Dryver R.; Guerrina, Mario; Nelson, Matthew

1997-09-01

The use of chloride-based deicing agents to help clear US highways of roadway hazards leads to associated chemical related problems. Fouling of local rivers and streams due to runoff of the water borne chlorides is significant and has contributed to local ordances are attempting to force state agencies to reduce, if not eliminate, the use of these chlorides. With respect to the corrosion aspects of chloride application, cracks that occur in the roadway/bridge pavement allow water to seep into the pavement carrying the chloride to the rebar with the resultant increase in corrosion. The costs of this corrosion are considerable and have led to the widespread use of chloride/water impermeable membranes on roadways and especially within bridges. Fiber optic sensor have repeatedly been shown to provide measurement capabilities of parameters within such reinforced concrete structures. Development of a fiber optic chloride sensors capable of being embedded within a roadway or bridge deck is reported.

Fiber optic Cerenkov radiation sensor system to estimate burn-up of spent fuel: characteristic evaluation of the system using Co-60 source

NASA Astrophysics Data System (ADS)

Shin, S. H.; Jang, K. W.; Jeon, D.; Hong, S.; Kim, S. G.; Sim, H. I.; Yoo, W. J.; Park, B. G.; Lee, B.

2013-09-01

Cerenkov radiation occurs when charged particles are moving faster than the speed of light in a transparent dielectric medium. In optical fibers, the Cerenkov light also can be generated due to their dielectric components. Accordingly, the radiation-induced light signals can be obtained using optical fibers without any scintillating material. In this study, to measure the intensities of Cerenkov radiation induced by gamma-rays, we have fabricated the fiber-optic Cerenkov radiation sensor system using silica optical fibers, plastic optical fibers, multi-anode photomultiplier tubes, and a scanning system. To characterize the Cerenkov radiation generated in optical fibers, the spectra of Cerenkov radiation generated in the silica and plastic optical fibers were measured. Also, the intensities of Cerenkov radiation induced by gamma-rays generated from a cylindrical Co-60 source with or without lead shielding were measured using the fiberoptic Cerenkov radiation sensor system.

Metal-coated optical fiber damage sensors

NASA Astrophysics Data System (ADS)

Chang, Chia-Chen; Sirkis, James S.

1993-07-01

A process which uses electroplating methods has been developed to fabricate metal coated optical fiber sensors. The elastic-plastic characteristics of the metal coatings have been exploited to develop a sensor capable of `remembering' low velocity impact damage. These sensors have been investigated under uniaxial tension testing of unembedded sensors and under low velocity impact of graphite/epoxy specimens with embedded sensors using both Michelson and polarimetric optical arrangements. The tests show that coating properties alter the optical fiber sensor performance and that the permanent deformation in the coating can be used to monitor composite delamination/impact damage.

Low cost fiber optic sensing of sugar solution

NASA Astrophysics Data System (ADS)

Muthuraju, M. E.; Patlolla, Anurag Reddy; Vadakkapattu Canthadai, Badrinath; Pachava, Vengalrao

2015-03-01

The demand for highly sensitive and reliable sensors to assess the refractive index of liquid get many applications in chemical and biomedical areas. Indeed, the physical parameters such as concentration, pressure and density, etc., can be found using the refractive index of liquid. In contrast to the conventional refractometer for measurement, optical fiber sensor has several advantages like remote sensing, small in size, low cost, immune to EMI etc., In this paper we have discussed determination of refractive index of sugar solution using optical fiber. An intensity modulated low cost plastic fiber optic refractive index sensor has been designed for the study. The sensor is based on principle of change in angle of reflected light caused by refractive index change of the medium surrounding the fiber. The experimental results obtained for the sugar solution of different refractive indices prove that the fiber optic sensor is cable of measuring the refractive indices as well as the concentrations.

Plasmonic Fiber Optic Refractometric Sensors: From Conventional Architectures to Recent Design Trends

PubMed Central

Klantsataya, Elizaveta; Jia, Peipei; Ebendorff-Heidepriem, Heike; Monro, Tanya M.; François, Alexandre

2016-01-01

Surface Plasmon Resonance (SPR) fiber sensor research has grown since the first demonstration over 20 year ago into a rich and diverse field with a wide range of optical fiber architectures, plasmonic coatings, and excitation and interrogation methods. Yet, the large diversity of SPR fiber sensor designs has made it difficult to understand the advantages of each approach. Here, we review SPR fiber sensor architectures, covering the latest developments from optical fiber geometries to plasmonic coatings. By developing a systematic approach to fiber-based SPR designs, we identify and discuss future research opportunities based on a performance comparison of the different approaches for sensing applications. PMID:28025532

Intrinsic Fabry-Perot optical fiber sensors and their multiplexing

DOEpatents

Wang, Anbo

2007-12-11

An intrinsic Fabry-Perot optical sensor includes a thin film sandwiched between two fiber ends. When light is launched into the fiber, two reflections are generated at the two fiber/thin film interfaces due to a difference in refractive indices between the fibers and the film, giving rise to the sensor output. In another embodiment, a portion of the cladding of a fiber is removed, creating two parallel surfaces. Part of the evanescent fields of light propagating in the fiber is reflected at each of the surfaces, giving rise to the sensor output. In a third embodiment, the refractive index of a small portion of a fiber is changed through exposure to a laser beam or other radiation. Interference between reflections at the ends of the small portion give rise to the sensor output. Multiple sensors along a single fiber are multiplexed using an optical time domain reflectometry method.

Thermal Strain Analysis of Optic Fiber Sensors

PubMed Central

Her, Shiuh-Chuan; Huang, Chih-Ying

2013-01-01

An optical fiber sensor surface bonded onto a host structure and subjected to a temperature change is analytically studied in this work. The analysis is developed in order to assess the thermal behavior of an optical fiber sensor designed for measuring the strain in the host structure. For a surface bonded optical fiber sensor, the measuring sensitivity is strongly dependent on the bonding characteristics which include the protective coating, adhesive layer and the bonding length. Thermal stresses can be generated due to a mismatch of thermal expansion coefficients between the optical fiber and host structure. The optical fiber thermal strain induced by the host structure is transferred via the adhesive layer and protective coating. In this investigation, an analytical expression of the thermal strain and stress in the optical fiber is presented. The theoretical predictions are validated using the finite element method. Numerical results show that the thermal strain and stress are linearly dependent on the difference in thermal expansion coefficients between the optical fiber and host structure and independent of the thermal expansion coefficients of the adhesive and coating. PMID:23385407

Optical fiber strain sensor with improved linearity range

NASA Technical Reports Server (NTRS)

Egalon, Claudio Oliveira (Inventor); Rogowski, Robert S. (Inventor)

1995-01-01

A strain sensor is constructed from a two mode optical fiber. When the optical fiber is surface mounted in a straight line and the object to which the optical fiber is mounted is subjected to strain within a predetermined range, the light intensity of any point at the output of the optical fiber will have a linear relationship to strain, provided the intermodal phase difference is less than 0.17 radians.

A review of fiber-optic corrosion sensor in civil engineering

NASA Astrophysics Data System (ADS)

Luo, Dong; Li, Junnan; Li, Yuanyuan

2018-05-01

Fiber-optical corrosion sensor (FOCS) is the research hotspot of corrosion monitoring sensor in recent years. It has the advantages of lightness, simplicity, anti-electromagnetic interference and distributed measurement, so it has an attractive application prospect. In this paper, the mechanism of metal corrosion is introduced. Several common methods for detecting optical fiber corrosion sensors are presented, and the latest progress of optical fiber corrosion sensors in recent years is described. We need to design a set of sensor devices that can directly monitor the corrosion of reinforcing steel bars directly, and propose a method of time dependent reliability assessment based on monitoring data, so as to form a complete research path.

A fiber-optic current sensor for aerospace applications

NASA Technical Reports Server (NTRS)

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

1990-01-01

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.

A fiber-optic current sensor for aerospace applications

NASA Technical Reports Server (NTRS)

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

1990-01-01

A robust, accurate, broadband, 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 used 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.

A fiber-optic current sensor for aerospace applications

NASA Technical Reports Server (NTRS)

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

1990-01-01

A robust, accurate, broadband, 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 (electromagnetic interference) 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 fiber-optic temperature sensor embedded in the sensing head. The authors report on the technology contained in the sensor and also relate the results of precision tests conducted at various temperatures within the wide operating range. The results of early EMI tests are shown.

Fiber-optic miniature sensor for in situ temperature monitoring of curing composite material

NASA Astrophysics Data System (ADS)

Sampath, Umesh; Kim, Dae-gil; Kim, Hyunjin; Song, Minho

2018-04-01

This study proposes a fiber-optic temperature sensor with a single-mode fiber tip covered with a thermo-sensitive polymer resin. The temperature is sensed by measuring the Fresnel reflection from the optical fiber/polymer interface. Because the thermo-optic coefficients differ between the optical fiber and the polymer, the in situ temperature can be measured even in curing composite materials. In initial experiments, the proposed sensor successfully measured and recovered the temperature information. The measured sensor data were linearly correlated, with an R2 exceeding 0.99. The standard deviation in the long-term measurements of constant temperature was 2.6%. The durability and stability of the sensor head material in long-term operation was validated by Fourier transform infrared spectroscopy and X-ray diffraction analysis. In further experiments, the suggested miniature temperature sensor obtained the internal temperatures of curing composite material over a wide range (30-110 °C).

Light backscatter fiber optic sensor: a new tool for predicting the stability of pork emulsions containing antioxidative potato protein hydrolysate.

PubMed

Nieto, Gema; Xiong, Youling L; Payne, Fred; Castillo, Manuel

2015-02-01

The objective of this study was to determine whether light backscatter response from fresh pork meat emulsions is correlated to final product stability indices. A specially designed fiber optic measurement system was used in combination with a miniature fiber optic spectrometer to determine the intensity of light backscatter within the wavelength range 300-1100 nm (UV/VIS/NIR) at different radial distances (2, 2.5 and 3mm) with respect to the light source in pork meat emulsions with two fat levels (15%, 30%) and two levels (0, 2.5%) of the natural antioxidant hydrolyzed potato protein (HPP). Textural parameters (hardness, deformability, cohesiveness and breaking force), cooking loss, TBARS (1, 2, 3, and 7 days of storage at 4 °C) and CIELAB color coordinates of cooked emulsions were measured. The light backscatter was directly correlated with cooking losses, color, breaking force and TBARS. The optical configuration proposed would compensate for the emulsion heterogeneity, maximizing the existing correlation between the optical signal and the emulsion quality metrics.

Fiber optic sensors for sub-centimeter spatially resolved measurements: Review and biomedical applications

NASA Astrophysics Data System (ADS)

Tosi, Daniele; Schena, Emiliano; Molardi, Carlo; Korganbayev, Sanzhar

2018-07-01

One of the current frontier of optical fiber sensors, and a unique asset of this sensing technology is the possibility to use a whole optical fiber, or optical fiber device, as a sensor. This solution allows shifting the whole sensing paradigm, from the measurement of a single physical parameter (such as temperature, strain, vibrations, pressure) to the measurement of a spatial distribution, or profiling, of a physical parameter along the fiber length. In the recent years, several technologies are achieving this task with unprecedentedly narrow spatial resolution, ranging from the sub-millimeter to the centimeter-level. In this work, we review the main fiber optic sensing technologies that achieve a narrow spatial resolution: Fiber Bragg Grating (FBG) dense arrays, chirped FBG (CFBG) sensors, optical frequency domain reflectometry (OFDR) based on either Rayleigh scattering or reflective elements, and microwave photonics (MWP). In the second part of the work, we present the impact of spatially dense fiber optic sensors in biomedical applications, where they find the main impact, presenting the key results obtained in thermo-therapies monitoring, high-resolution diagnostic, catheters monitoring, smart textiles, and other emerging applicative fields.

Vibration sensing in flexible structures using a distributed-effect modal domain optical fiber sensor

NASA Technical Reports Server (NTRS)

Reichard, Karl M.; Lindner, Douglas K.; Claus, Richard O.

1991-01-01

Modal domain optical fiber sensors have recently been employed in the implementation of system identification algorithms and the closed-loop control of vibrations in flexible structures. The mathematical model of the modal domain optical fiber sensor used in these applications, however, only accounted for the effects of strain in the direction of the fiber's longitudinal axis. In this paper, we extend this model to include the effects of arbitrary stress. Using this sensor model, we characterize the sensor's sensitivity and dynamic range.

Distributed optical fiber dynamic magnetic field sensor based on magnetostriction.

PubMed

Masoudi, Ali; Newson, Trevor P

2014-05-01

A distributed optical fiber sensor is introduced which is capable of quantifying multiple magnetic fields along a 1 km sensing fiber with a spatial resolution of 1 m. The operation of the proposed sensor is based on measuring the magnetorestrictive induced strain of a nickel wire attached to an optical fiber. The strain coupled to the optical fiber was detected by measuring the strain-induced phase variation between the backscattered Rayleigh light from two segments of the sensing fiber. A magnetic field intensity resolution of 0.3 G over a bandwidth of 50-5000 Hz was demonstrated.

Piezoelectric bimorph optical-fiber sensor.

PubMed

Sun, Fengguo; Xiao, Gaozhi; Zhang, Zhiyi; Grover, Chander P

2004-03-20

We propose and demonstrate a novel high-voltage optical-fiber sensor. This sensor consists of an emitting fiber, a receiving fiber, and a piezoelectric bimorph transducer. The emitting fiber is fixed in a base, whereas the receiving fiber is mounted on the free end of the piezoelectric bimorph transducer. When a voltage is applied to the piezoelectric bimorph transducer, its free end is displaced over a distance delta. The displacement induces a loss in the optical coupling between the emitting and the receiving fiber. The voltage can be measured by monitoring the coupling loss.

Combined electromechanical impedance and fiber optic diagnosis of aerospace structures

NASA Astrophysics Data System (ADS)

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

2014-03-01

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.

Development of Metal Oxide Nanostructure-based Optical Sensors for Fossil Fuel Derived Gases Measurement at High Temperature

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Kevin P.

2015-02-13

This final technical report details research works performed supported by a Department of Energy grant (DE-FE0003859), which was awarded under the University Coal Research Program administrated by National Energy Technology Laboratory. This research program studied high temperature fiber sensor for harsh environment applications. It developed two fiber optical sensor platform technology including regenerative fiber Bragg grating sensors and distributed fiber optical sensing based on Rayleigh backscattering optical frequency domain reflectometry. Through the studies of chemical and thermal regenerative techniques for fiber Bragg grating (FBG) fabrication, high-temperature stable FBG sensors were successfully developed and fabricated in air-hole microstructured fibers, high-attenuation fibers,more » rare-earth doped fibers, and standard telecommunication fibers. By optimizing the laser processing and thermal annealing procedures, fiber grating sensors with stable performance up to 1100°C have been developed. Using these temperature-stable FBG gratings as sensor platform, fiber optical flow, temperature, pressure, and chemical sensors have been developed to operate at high temperatures up to 800°C. Through the integration of on-fiber functional coating, the use of application-specific air-hole microstructural fiber, and application of active fiber sensing scheme, distributed fiber sensor for temperature, pressure, flow, liquid level, and chemical sensing have been demonstrated with high spatial resolution (1-cm or better) with wide temperature ranges. These include the demonstration of 1) liquid level sensing from 77K to the room temperature, pressure/temperature sensing from the room temperature to 800C and from the 15psi to 2000 psi, and hydrogen concentration measurement from 0.2% to 10% with temperature ranges from the room temperature to 700°C. Optical sensors developed by this program has broken several technical records including flow sensors with the highest operation temperature up to 750°C, first distributed chemical measurements at the record high temperature up to 700°C, first distributed pressure measurement at the record high temperature up to 800°C, and the fiber laser sensors with the record high operation temperature up to 700°C. The research performed by this program dramatically expand the functionality, adaptability, and applicability of distributed fiber optical sensors with potential applications in a number of high-temperature energy systems such as fossil-fuel power generation, high-temperature fuel cell applications, and potential for nuclear energy systems.« less

Development of a 2-channel embedded infrared fiber-optic temperature sensor using silver halide optical fibers.

PubMed

Yoo, Wook Jae; Jang, Kyoung Won; Seo, Jeong Ki; Moon, Jinsoo; Han, Ki-Tek; Park, Jang-Yeon; Park, Byung Gi; Lee, Bongsoo

2011-01-01

A 2-channel embedded infrared fiber-optic temperature sensor was fabricated using two identical silver halide optical fibers for accurate thermometry without complicated calibration processes. In this study, we measured the output voltages of signal and reference probes according to temperature variation over a temperature range from 25 to 225 °C. To decide the temperature of the water, the difference between the amounts of infrared radiation emitted from the two temperature sensing probes was measured. The response time and the reproducibility of the fiber-optic temperature sensor were also obtained. Thermometry with the proposed sensor is immune to changes if parameters such as offset voltage, ambient temperature, and emissivity of any warm object. In particular, the temperature sensing probe with silver halide optical fibers can withstand a high temperature/pressure and water-chemistry environment. It is expected that the proposed sensor can be further developed to accurately monitor temperature in harsh environments.

In-line optical fiber sensors based on cladded multimode tapered fibers.

PubMed

Villatoro, Joel; Monzón-Hernández, David; Luna-Moreno, Donato

2004-11-10

The use of uniform-waist cladded multimode tapered optical fibers is demonstrated for evanescent wave spectroscopy and sensors. The tapering is a simple, low-loss process and consists of stretching the fiber while it is being heated with an oscillating flame torch. As examples, a refractive-index sensor and a hydrogen sensor are demonstrated by use of a conventional graded-index multimode optical fiber. Also, absorbance spectra are measured while the tapers are immersed in an absorbing liquid. It is found experimentally that the uniform waist is the part of the taper that contributes most to the sensor sensitivity. The taper waist diameter may also be used to adjust the sensor dynamic range.

Fiber optic sensor employing successively destroyed coupled points or reflectors for detecting shock wave speed and damage location

DOEpatents

Weiss, Jonathan D.

1995-01-01

A shock velocity and damage location sensor providing a means of measuring shock speed and damage location. The sensor consists of a long series of time-of-arrival "points" constructed with fiber optics. The fiber optic sensor apparatus measures shock velocity as the fiber sensor is progressively crushed as a shock wave proceeds in a direction along the fiber. The light received by a receiving means changes as time-of-arrival points are destroyed as the sensor is disturbed by the shock. The sensor may comprise a transmitting fiber bent into a series of loops and fused to a receiving fiber at various places, time-of-arrival points, along the receiving fibers length. At the "points" of contact, where a portion of the light leaves the transmitting fiber and enters the receiving fiber, the loops would be required to allow the light to travel backwards through the receiving fiber toward a receiving means. The sensor may also comprise a single optical fiber wherein the time-of-arrival points are comprised of reflection planes distributed along the fibers length. In this configuration, as the shock front proceeds along the fiber it destroys one reflector after another. The output received by a receiving means from this sensor may be a series of downward steps produced as the shock wave destroys one time-of-arrival point after another, or a nonsequential pattern of steps in the event time-of-arrival points are destroyed at any point along the sensor.

Fiber optic sensor employing successively destroyed coupled points or reflectors for detecting shock wave speed and damage location

DOEpatents

Weiss, J.D.

1995-08-29

A shock velocity and damage location sensor providing a means of measuring shock speed and damage location is disclosed. The sensor consists of a long series of time-of-arrival ``points`` constructed with fiber optics. The fiber optic sensor apparatus measures shock velocity as the fiber sensor is progressively crushed as a shock wave proceeds in a direction along the fiber. The light received by a receiving means changes as time-of-arrival points are destroyed as the sensor is disturbed by the shock. The sensor may comprise a transmitting fiber bent into a series of loops and fused to a receiving fiber at various places, time-of-arrival points, along the receiving fibers length. At the ``points`` of contact, where a portion of the light leaves the transmitting fiber and enters the receiving fiber, the loops would be required to allow the light to travel backwards through the receiving fiber toward a receiving means. The sensor may also comprise a single optical fiber wherein the time-of-arrival points are comprised of reflection planes distributed along the fibers length. In this configuration, as the shock front proceeds along the fiber it destroys one reflector after another. The output received by a receiving means from this sensor may be a series of downward steps produced as the shock wave destroys one time-of-arrival point after another, or a nonsequential pattern of steps in the event time-of-arrival points are destroyed at any point along the sensor. 6 figs.

Extrinsic fiber optic displacement sensors and displacement sensing systems

DOEpatents

Murphy, K.A.; Gunther, M.F.; Vengsarkar, A.M.; Claus, R.O.

1994-04-05

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. 14 figures.

Extrinsic fiber optic displacement sensors and displacement sensing systems

DOEpatents

Murphy, Kent A.; Gunther, Michael F.; Vengsarkar, Ashish M.; Claus, Richard O.

1994-01-01

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.

Moisture sensor based on evanescent wave light scattering by porous sol-gel silica coating

DOEpatents

Tao, Shiquan; Singh, Jagdish P.; Winstead, Christopher B.

2006-05-02

An optical fiber moisture sensor that can be used to sense moisture present in gas phase in a wide range of concentrations is provided, as well techniques for making the same. The present invention includes a method that utilizes the light scattering phenomenon which occurs in a porous sol-gel silica by coating an optical fiber core with such silica. Thus, a porous sol-gel silica polymer coated on an optical fiber core forms the transducer of an optical fiber moisture sensor according to an embodiment. The resulting optical fiber sensor of the present invention can be used in various applications, including to sense moisture content in indoor/outdoor air, soil, concrete, and low/high temperature gas streams.

Design of a fiber-optic interrogator module for telecommunication satellites

NASA Astrophysics Data System (ADS)

Putzer, Philipp; Koch, Alexander W.; Plattner, Markus; Hurni, Andreas; Manhart, Markus

2017-11-01

In this paper we present the results of the radiation tests performed on the optical components of the fiber-optic interrogator module as a part of the Hybrid Sensor Bus (HSB) system. The HSB-system is developed in the frame of an ESAARTES program and will be verified as flight demonstrator onboard the German Heinrich Hertz satellite in 2016. The HSB system is based on a modular concept which includes sensor interrogation modules based on I2C electrical and fiber Bragg grating (FBG) fiber-optical sensor elements. Onboard fiber-optic sensing allows the implementation of novel control and monitoring methods. For read-out of multiple FBG sensors, a design based on a tunable laser diode as well as a design based on a spectrometer is considered. The expected and tested total ionizing dose (TID) applicable to the HSB system is in the range between 100 krad and 300 krad inside the satellite in the geostationary orbit over a life time of 15 years. We present radiation test results carried out on critical optical components to be used in the fiber-optic interrogation module. These components are a modulated grating Y-branch (MGY) tunable laser diode acting as light source for the tuning laser approach, the line detector of a spectrometer, photodetectors and the FBG sensors acting as sensor elements. A detailed literature inquiry of radiation effects on optical fibers and FBG sensors, is also included in the paper. The fiber-optic interrogator module implemented in the HSB system is based on the most suitable technology, which sustains the harsh environment in the geostationary orbit.

Research Progress on F-P Interference—Based Fiber-Optic Sensors

PubMed Central

Huang, Yi Wen; Tao, Jin; Huang, Xu Guang

2016-01-01

We review our works on Fabry-Perot (F-P) interferometric fiber-optic sensors with various applications. We give a general model of F-P interferometric optical fiber sensors including diffraction loss caused by the beam divergence and the Gouy phase shift. Based on different structures of an F-P cavity formed on the end of a single-mode fiber, the F-P interferometric optical sensor has been extended to measurements of the refractive index (RI) of liquids and solids, temperature as well as small displacement. The RI of liquids and solids can be obtained by monitoring the fringe contrast related to Fresnel reflections, while the ambient temperature and small displacement can be obtained by monitoring the wavelength shift of the interference fringes. The F-P interferometric fiber-optic sensors can be used for many scientific and technological applications. PMID:27598173

Spatial Frequency Multiplexing of Fiber-Optic Interferometric Refractive Index Sensors Based on Graded-Index Multimode Fibers

PubMed Central

Liu, Li; Gong, Yuan; Wu, Yu; Zhao, Tian; Wu, Hui-Juan; Rao, Yun-Jiang

2012-01-01

Fiber-optic interferometric sensors based on graded-index multimode fibers have very high refractive-index sensitivity, as we previously demonstrated. In this paper, spatial-frequency multiplexing of this type of fiber-optic refractive index sensors is investigated. It is estimated that multiplexing of more than 10 such sensors is possible. In the multiplexing scheme, one of the sensors is used to investigate the refractive index and temperature responses. The fast Fourier transform (FFT) of the combined reflective spectra is analyzed. The intensity of the FFT spectra is linearly related with the refractive index and is not sensitive to the temperature.

Reannealed Fiber Bragg Gratings Demonstrated High Repeatability in Temperature Measurements

NASA Technical Reports Server (NTRS)

Adamovsky, Grigory; Juergens, Jeffrey R.

2004-01-01

Fiber Bragg gratings (FBGs) are formed by periodic variations of the refractive index of an optical fiber. These periodic variations allow an FBG to act as an embedded optical filter, passing the majority of light propagating through a fiber while reflecting back a narrow band of the incident light. The peak reflected wavelength of the FBG is known as the Bragg wavelength. Since the period and width of the refractive index variation in the fiber determines the wavelengths that are transmitted and reflected by the grating, any force acting on the fiber that alters the physical structure of the grating will change the wavelengths that are transmitted and reflected by it. Both thermal and mechanical forces acting on the grating will alter its physical characteristics, allowing the FBG sensor to detect both the temperature variations and the physical stresses and strains placed upon it. This ability to sense multiple physical forces makes the FBG a versatile sensor. To assess the feasibility of using Bragg gratings as temperature sensors for propulsion applications, researchers at the NASA Glenn Research Center evaluated the performance of Bragg gratings at elevated temperatures for up to 300 C. For these purposes, commercially available polyimide-coated high-temperature gratings were used that were annealed by the manufacturer to 300 C. To assure the most thermally stable gratings at the operating temperatures, we reannealed the gratings to 400 C at a very slow rate for 12 to 24 hr until their reflected optical powers were stabilized. The reannealed gratings were then subjected to periodic thermal cycling from room temperature to 300 C, and their peak reflected wavelengths were monitored. The setup shown is used for reannealing and thermal cycling the FBGs. Signals from the photodetectors and the spectrum analyzer were fed into a computer equipped with LabVIEW software. The software synchronously monitored the oven/furnace temperature and the optical spectrum analyzer as well as processed the data. Experimental results presented in the following graph show typical wavelength versus temperature dependence of a reannealed FBG through six thermal cycles (80 hr). The average standard deviation of the temperature-to-wavelength relationship ranged from 1.86 to 2.92 C over the six thermal cycles each grating was subjected to. This is an error of less than 1.0 percent of full scale throughout the entire evaluation temperature range from ambient to 300 C.

Fiber-optic interferometric sensors for measurements of pressure fluctuations: Experimental evaluation

NASA Technical Reports Server (NTRS)

Cho, Y. C.; Soderman, P. T.

1993-01-01

This paper addresses an anechoic chamber evaluation of a fiber-optic interferometric sensor (fiber-optic microphone), which is being developed at NASA Ames Research Center for measurements of pressure fluctuations in wind tunnels.

Electro-optic architecture (EOA) for sensors and actuators in aircraft propulsion systems

NASA Technical Reports Server (NTRS)

Glomb, W. L., Jr.

1989-01-01

Results of a study to design an optimal architecture for electro-optical sensing and control in advanced aircraft and space systems are described. The propulsion full authority digital Electronic Engine Control (EEC) was the focus for the study. The recommended architecture is an on-engine EEC which contains electro-optic interface circuits for fiber-optic sensors on the engine. Size and weight are reduced by multiplexing arrays of functionally similar sensors on a pair of optical fibers to common electro-optical interfaces. The architecture contains common, multiplex interfaces to seven sensor groups: (1) self luminous sensors; (2) high temperatures; (3) low temperatures; (4) speeds and flows; (5) vibration; (6) pressures; and (7) mechanical positions. Nine distinct fiber-optic sensor types were found to provide these sensing functions: (1) continuous wave (CW) intensity modulators; (2) time division multiplexing (TDM) digital optic codeplates; (3) time division multiplexing (TDM) analog self-referenced sensors; (4) wavelength division multiplexing (WDM) digital optic code plates; (5) wavelength division multiplexing (WDM) analog self-referenced intensity modulators; (6) analog optical spectral shifters; (7) self-luminous bodies; (8) coherent optical interferometers; and (9) remote electrical sensors. The report includes the results of a trade study including engine sensor requirements, environment, the basic sensor types, and relevant evaluation criteria. These figures of merit for the candidate interface types were calculated from the data supplied by leading manufacturers of fiber-optic sensors.

Fiber-Optic Distribution Of Pulsed Power To Multiple Sensors

NASA Technical Reports Server (NTRS)

Kirkham, Harold

1996-01-01

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

Civil infrastructure monitoring for IVHS using optical fiber sensors

NASA Astrophysics Data System (ADS)

de Vries, Marten J.; Arya, Vivek; Grinder, C. R.; Murphy, Kent A.; Claus, Richard O.

1995-01-01

8Early deployment of Intelligent Vehicle Highway Systems would necessitate the internal instrumentation of infrastructure for emergency preparedness. Existing quantitative analysis and visual analysis techniques are time consuming, cost prohibitive, and are often unreliable. Fiber optic sensors are rapidly replacing conventional instrumentation because of their small size, light weight, immunity to electromagnetic interference, and extremely high information carrying capability. In this paper research on novel optical fiber sensing techniques for health monitoring of civil infrastructure such as highways and bridges is reported. Design, fabrication, and implementation of fiber optic sensor configurations used for measurements of strain are discussed. Results from field tests conducted to demonstrate the effectiveness of fiber sensors at determining quantitative strain vector components near crack locations in bridges are presented. Emerging applications of fiber sensors for vehicle flow, vehicle speed, and weigh-in-motion measurements are also discussed.

Development of advanced seal verification

NASA Technical Reports Server (NTRS)

Workman, Gary L.; Kosten, Susan E.; Abushagur, Mustafa A.

1992-01-01

The purpose of this research is to develop a technique to monitor and insure seal integrity with a sensor that has no active elements to burn-out during a long duration activity, such as a leakage test or especially during a mission in space. The original concept proposed is that by implementing fiber optic sensors, changes in the integrity of a seal can be monitored in real time and at no time should the optical fiber sensor fail. The electrical components which provide optical excitation and detection through the fiber are not part of the seal; hence, if these electrical components fail, they can be easily changed without breaking the seal. The optical connections required for the concept to work does present a functional problem to work out. The utility of the optical fiber sensor for seal monitoring should be general enough that the degradation of a seal can be determined before catastrophic failure occurs and appropriate action taken. Two parallel efforts were performed in determining the feasibility of using optical fiber sensors for seal verification. In one study, research on interferometric measurements of the mechanical response of the optical fiber sensors to seal integrity was studied. In a second study, the implementation of the optical fiber to a typical vacuum chamber was implemented and feasibility studies on microbend experiments in the vacuum chamber were performed. Also, an attempt was made to quantify the amount of pressure actually being applied to the optical fiber using finite element analysis software by Algor.

Optical fiber sensor based on surface plasmon resonance for rapid detection of avian influenza virus subtype H6: Initial studies.

PubMed

Zhao, Xihong; Tsao, Yu-Chia; Lee, Fu-Jung; Tsai, Woo-Hu; Wang, Ching-Ho; Chuang, Tsung-Liang; Wu, Mu-Shiang; Lin, Chii-Wann

2016-07-01

A side-polished fiber optic surface plasmon resonance (SPR) sensor was fabricated to expose the core surface and then deposited with a 40 nm thin gold film for the near surface sensing of effective refractive index changes with surface concentration or thickness of captured avian influenza virus subtype H6. The detection surface of the SPR optical fiber sensor was prepared through the plasma modification method for binding a self-assembled monolayer of isopropanol chemically on the gold surface of the optical fiber. Subsequently, N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide/N-hydroxysuccinimide was activated to enable EB2-B3 monoclonal antibodies to capture A/chicken/Taiwan/2838V/00 (H6N1) through a flow injection system. The detection limit of the fabricated optical fiber sensor for A/chicken/Taiwan/2838V/00 was 5.14 × 10(5) EID50/0.1 mL, and the response time was 10 min on average. Moreover, the fiber optic sensor has the advantages of a compact size and low cost, thus rendering it suitable for online and remote sensing. The results indicated that the optical fiber sensor can be used for epidemiological surveillance and diagnosing of avian influenza subtype H6 rapidly. Copyright © 2016 Elsevier B.V. All rights reserved.

Energetic radiation influence on temperature dependency of Brillouin frequency in optical fibers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pheron, X.; Ouerdane, Y.; Delepine-Lesoille, S.

We present a post mortem study of the influence of energetic radiation on optical fiber Brillouin sensors, both Brillouin spectrum and its temperature dependency in two different fibers, a photosensitive optical fiber and a SMF28. The target application is nuclear wastes repository monitoring where optical fiber Brillouin sensors might be exposed to energetic radiation. UV exposure induced optical losses, Brillouin frequency shifts up to 28 MHz and even a variation of the temperature dependency. The photosensitive optical fiber resulted more sensitive than SMF28{sup TM}. (authors)

Corrosion detection in reinforced concrete roadways and bridges via embedded fiber optic sensors

NASA Astrophysics Data System (ADS)

Fuhr, Peter L.; Huston, Dryver R.

1998-04-01

The problems associated with the application of chloride-based deicing agents to roadways and specifically bridges include chemical pollution and accelerated corrosion of strength members (especially the rebar) within the structure. In many instances, local ordnances are attempting to force state agencies to reduce, if not eliminate, the use of these chlorides (typically at the cost of increased driving hazards). With respect to the corrosion aspects of chloride application, cracks that occur in the roadway/bridge pavement allow water to seep into the pavement carrying the chloride to the rebar with the resultant increase in corrosion. In tandem with these efforts has been the continuing use of embedded fiber optic sensors for identification of faults or cracks within a highway structure - i.e., structural health monitoring. In this paper, we present multiple-parameter sensing fiber optic sensors which may be embedded into roadway and bridge structures to provide an internal measurement and assessment of its health. Such issues are paramount in determining if remedial or preventative maintenance should be performed on such structures. Laboratory results, comparisons with conventional sensing methods as well as a review of real-world issues in highway sensing are presented.

Fiber temperature sensor with nanostructured cladding by TiO2 nanoparticles self-assembled onto a side polished optical fiber

NASA Astrophysics Data System (ADS)

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

2015-07-01

A temperature fiber sensor with nanostructured cladding composed ted by titanium dioxide (TiO2) nanoparticles was demonstrated. The nanoparticles self-assembled onto a side polished optical fiber (SPF). The enhancement of interaction between the propagating light and the TiO2 nanoparticles (TN) can be obtained via strong evanescent field of the SPF. The strong light-TN interaction gives rise to temperature sensing with a optical power variation of ~4dB in SPF experimentally for an environment temperature ranging from -7.8°C to 77.6°C. The novel temperature sensor shows a sensitivity of ~0.044 dB/°C. The TN-based fiber-optic temperature sensor is facile to manufactured, compatible with fiber-optic interconnections and high potential in photonics applications.

Monitoring industrial facilities using principles of integration of fiber classifier and local sensor networks

NASA Astrophysics Data System (ADS)

Korotaev, Valery V.; Denisov, Victor M.; Rodrigues, Joel J. P. C.; Serikova, Mariya G.; Timofeev, Andrey V.

2015-05-01

The paper deals with the creation of integrated monitoring systems. They combine fiber-optic classifiers and local sensor networks. These systems allow for the monitoring of complex industrial objects. Together with adjacent natural objects, they form the so-called geotechnical systems. An integrated monitoring system may include one or more spatially continuous fiber-optic classifiers based on optic fiber and one or more arrays of discrete measurement sensors, which are usually combined in sensor networks. Fiber-optic classifiers are already widely used for the control of hazardous extended objects (oil and gas pipelines, railways, high-rise buildings, etc.). To monitor local objects, discrete measurement sensors are generally used (temperature, pressure, inclinometers, strain gauges, accelerometers, sensors measuring the composition of impurities in the air, and many others). However, monitoring complex geotechnical systems require a simultaneous use of continuous spatially distributed sensors based on fiber-optic cable and connected local discrete sensors networks. In fact, we are talking about integration of the two monitoring methods. This combination provides an additional way to create intelligent monitoring systems. Modes of operation of intelligent systems can automatically adapt to changing environmental conditions. For this purpose, context data received from one sensor (e.g., optical channel) may be used to change modes of work of other sensors within the same monitoring system. This work also presents experimental results of the prototype of the integrated monitoring system.

State of the art in high-temperature fiber optic sensors

NASA Astrophysics Data System (ADS)

Fielder, Robert S.; Stinson-Bagby, Kelly L.; Palmer, Matthew E.

2004-12-01

The objective of the work presented was to develop a suite of sensors for use in high-temperature aerospace environments, including turbine engine monitoring, hypersonic vehicle skin friction measurements, and support ground and flight test operations. A fiber optic sensor platform was used to construct the sensor suite. Successful laboratory demonstrations include calibration of pressure sensors to 500psi at a gas temperature of 800°C. Additionally, pressure sensors were demonstrated at 800°C in combination with a high-speed (1.0MHz) fiber optic readout system enabling previously unobtainable dynamic measurements at high-temperatures. Temperature sensors have been field tested up to 1400°C and as low as -195°C. The key advancement that enabled the operation of these novel harsh environment sensors was a fiber optic packaging methodology that allowed the coupling of alumina and sapphire transducer components, optical fiber, and high-temperature alloy housing materials. The basic operation of the sensors and early experimental results are presented. Each of the sensors described here represent a quantifiable advancement in the state of the art in high-temperature physical sensors and will have a significant impact on the aerospace propulsion instrumentation industry.

Multiple channel optical data acquisition system

DOEpatents

Fasching, G.E.; Goff, D.R.

1985-02-22

A multiple channel optical data acquisition system is provided in which a plurality of remote sensors monitoring specific process variable are interrogated by means of a single optical fiber connecting the remote station/sensors to a base station. The remote station/sensors derive all power from light transmitted through the fiber from the base station. Each station/sensor is individually accessed by means of a light modulated address code sent over the fiber. The remote station/sensors use a single light emitting diode to both send and receive light signals to communicate with the base station and provide power for the remote station. The system described can power at least 100 remote station/sensors over an optical fiber one mile in length.

Planar and finger-shaped optical tactile sensors for robotic applications

NASA Technical Reports Server (NTRS)

Begej, Stefan

1988-01-01

Progress is described regarding the development of optical tactile sensors specifically designed for application to dexterous robotics. These sensors operate on optical principles involving the frustration of total internal reflection at a waveguide/elastomer interface and produce a grey-scale tactile image that represents the normal (vertical) forces of contact. The first tactile sensor discussed is a compact, 32 x 32 planar sensor array intended for mounting on a parallel-jaw gripper. Optical fibers were employed to convey the tactile image to a CCD camera and microprocessor-based image analysis system. The second sensor had the shape and size of a human fingertip and was designed for a dexterous robotic hand. It contained 256 sensing sites (taxels) distributed in a dual-density pattern that included a tactile fovea near the tip measuring 13 x 13 mm and containing 169 taxels. The design and construction details of these tactile sensors are presented, in addition to photographs of tactile imprints.

Polymer Optical Fiber Sensor and the Prediction of Sensor Response Utilizing Artificial Neural Networks

NASA Astrophysics Data System (ADS)

Haroglu, Derya

The global market researches showed that there is a growing trend in the field of polymer optical fiber (POF) and POF sensors. Telecommunications, medicine, defense, aerospace, and automotive are the application areas of fiber optic sensors, where the automotive industry is the most promising application area for innovations in the field of POF sensors. The POF sensors in automobiles are particularly for detection of seat occupancy, and intelligent pedestrian protection systems. This dissertation investigates graded index perfluorinated polymer optical fiber as an intensity modulated intrinsic sensor for application in automotive seat occupancy sensing. Since a fiber optic sensor has a high bandwidth, is small in size, is lightweight, and is immune to electromagnetic interference (EMI) it offers higher performance than that of its electrical based counterparts such as strain gauge, elastomeric bladder, and resistive sensor systems. This makes the fiber optic sensor a potential suitable material for seat occupancy sensing. A textile-based fiber optic sensor was designed to be located in the area beneath the typical seated human's thighs. The pressure interval under which the proposed POF sensor design could perform well was found to be between 0.18 and 0.21 N/cm2, where perfluorinated (PF) graded index (GI) POF (62.5/750 mum) was used as the POF material. In addition, the effect of the automotive seat covering including face material (fabric) and foam backing to the sensor's performance was analyzed. The face fabric structure and the thickness of foam backing were not found to be significant factors to change the sensor results. A research study, survey, was conducted of which purpose was to better understand market demands in terms of sensor performance characteristics for automotive seat weight sensors, as a part of the Quality Function Deployment (QFD) House of Quality analysis. The companies joined the survey agreed on the first 5 most important sensor characteristics: reproducibility, accuracy, selectivity, aging, and resolution. Artificial neural network (ANN), a mathematical model formed by mimicking the human nervous system, was used to predict the sensor response. Qwiknet (version 2.23) software was used to develop ANNs and according to the results of Qwiknet the prediction performances for training and testing data sets were 75%, and 83.33% respectively. In this dissertation, Chapter 1 describes the worldwide plastic optical fiber (POF) and fiber optic sensor markets, and the existing textile structures used in fiber optic sensing design particularly for the applications of biomedical and structural health monitoring (SHM). Chapter 2 provides a literature review in detail on polymer optical fibers, fiber optic sensors, and occupancy sensing in the passenger seats of automobiles. Chapter 3 includes the research objectives. Chapter 4 presents the response of POF to tensile loading, bending, and cyclic tensile loading with discussion parts. Chapter 5 includes an e-mail based survey to prioritize customer needs in a Quality Function Deployment (QFD) format utilizing Analytic Hierarchy Process (AHP) and survey results. Chapter 6 describes the POF sensor design and the behavior of it under pressure. Chapter 7 provides a data analysis based on the experimental results of Chapter 6. Chapter 8 presents the summary of this study and recommendations for future work.

Toward Optical Sensors: Review and Applications

NASA Astrophysics Data System (ADS)

Sabri, Naseer; Aljunid, S. A.; Salim, M. S.; Ahmad, R. B.; Kamaruddin, R.

2013-04-01

Recent advances in fiber optics (FOs) and the numerous advantages of light over electronic systems have boosted the utility and demand for optical sensors in various military, industry and social fields. Environmental and atmospheric monitoring, earth and space sciences, industrial chemical processing and biotechnology, law enforcement, digital imaging, scanning, and printing are exemplars of them. The ubiquity of photonic technologies could drive down prices which reduced the cost of optical fibers and lasers. Fiber optic sensors (FOSs) offer a wide spectrum of advantages over traditional sensing systems, such as small size and longer lifetime. Immunity to electromagnetic interference, amenability to multiplexing, and high sensitivity make FOs the sensor technology of choice in several fields, including the healthcare and aerospace sectors. FOSs show reliable and rigid sensing tasks over conventional electrical and electronic sensors. This paper presents an executive review of optical fiber sensors and the most beneficial applications.

The family of micro sensors for remote control the pollution in liquids and gases

NASA Astrophysics Data System (ADS)

Tulaikova, Tamara; Kocharyun, Gevorg; Rogerson, Graham; Burmistrova, Ludmyla; Sychugov, Vladimir; Dorojkin, Peter

2005-10-01

There are the results for the 3 groups of fiber-optical sensors. First is the fiber-optical sensor with changed sensitive heads on the base on porous polymer with clamped activated dye. Vibration method for fiber-optical sensors provides more convenient output measurements of resonant frequency changes, in comparison with the first device. The self-focusing of the living sells into optical wave-guides in laser road in water will be considered as a new touch method for environment remote sensing.

Optical fiber sensors for life support applications

NASA Technical Reports Server (NTRS)

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

1992-01-01

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

Advances in fiber optic sensors for in-vivo monitoring

NASA Astrophysics Data System (ADS)

Baldini, Francesco; Mignani, Anna G.

1995-09-01

Biomedical fiber-optic sensors are attractive for the measurement of both physical and chemical parameters as well as for spectral measurements directly performed on the patient. An overview of fiber-optic sensors for in vivo monitoring is given, with particular attention to the advantages that these sensors are able to offer in different fields of application such as cardiovascular and intensive care, angiology, gastroenterology, ophthalmology, oncology, neurology, dermatology, and dentistry.

Experimental Validation of Thermal Retinal Models of Damage from Laser Radiation

DTIC Science & Technology

1979-08-01

for measuring relative intensity profile with a thermocouple or fiber-optic sensor .............................................. 72 B-2 Calculated...relative intensity profiles meas- ured by 5- and 10-pm-radius sensors of a Gaussian beam, with standard deviation of 10 Pm...the Air Force de - veloped a model for the mathematical prediction of thermal ef- fects of laser radiation on the eye (8). Given the characteris- tics

Design of Oil Viscosity Sensor Based on Plastic Optical Fiber

NASA Astrophysics Data System (ADS)

Yunus, Muhammad; Arifin, A.

2018-03-01

A research of plastic optical fiber based sensors have been studied for measurement of oil viscosity. This sensor was made with straight configuration, U configuration, and gamma configuration have two types, there are optical fiber sensor with cladding and without cladding. Viscosity sensor was made, dipped into an oil sample with a concentration of viscosity percentage about 270 mPa.s - 350 mPa.s. The light from the LED propagated into the optical fiber, then it was received by the photodetector converted to output power. When plastic optical fiber dipped into an oil sample, viscosity of oil affect increase of refractive index on optical fiber resulting in a bigger loss of power so the light intensity will be smaller, consequences the measured output power will be smaller. Sensitivity and resolution viscosity sensor without cladding peel showed the best result rather than viscosity sensor with cladding peel. The best result in the measurement showed in gamma configuration with 3 cm length of cladding peel and the diameter of bending 0,25 cm is the range 103,090 nWatt, sensitivity 1,289 nWatt/mPa.s, and resolution 0,776 mPa.s. This method is effectively and efficiently used as an oil viscosity sensor with high sensitivity and resolution.

Graphene Oxide in Lossy Mode Resonance-Based Optical Fiber Sensors for Ethanol Detection.

PubMed

Hernaez, Miguel; Mayes, Andrew G; Melendi-Espina, Sonia

2017-12-27

The influence of graphene oxide (GO) over the features of an optical fiber ethanol sensor based on lossy mode resonances (LMR) has been studied in this work. Four different sensors were built with this aim, each comprising a multimode optical fiber core fragment coated with a SnO₂ thin film. Layer by layer (LbL) coatings made of 1, 2 and 4 bilayers of polyethyleneimine (PEI) and graphene oxide were deposited onto three of these devices and their behavior as aqueous ethanol sensors was characterized and compared with the sensor without GO. The sensors with GO showed much better performance with a maximum sensitivity enhancement of 176% with respect to the sensor without GO. To our knowledge, this is the first time that GO has been used to make an optical fiber sensor based on LMR.

Noninvasive blood pressure measurement scheme based on optical fiber sensor

NASA Astrophysics Data System (ADS)

Liu, Xianxuan; Yuan, Xueguang; Zhang, Yangan

2016-10-01

Optical fiber sensing has many advantages, such as volume small, light quality, low loss, strong in anti-jamming. Since the invention of the optical fiber sensing technology in 1977, optical fiber sensing technology has been applied in the military, national defense, aerospace, industrial, medical and other fields in recent years, and made a great contribution to parameter measurement in the environment under the limited condition .With the rapid development of computer, network system, the intelligent optical fiber sensing technology, the sensor technology, the combination of computer and communication technology , the detection, diagnosis and analysis can be automatically and efficiently completed. In this work, we proposed a noninvasive blood pressure detection and analysis scheme which uses optical fiber sensor. Optical fiber sensing system mainly includes the light source, optical fiber, optical detector, optical modulator, the signal processing module and so on. wavelength optical signals were led into the optical fiber sensor and the signals reflected by the human body surface were detected. By comparing actual testing data with the data got by traditional way to measure the blood pressure we can establish models for predicting the blood pressure and achieve noninvasive blood pressure measurement by using spectrum analysis technology. Blood pressure measurement method based on optical fiber sensing system is faster and more convenient than traditional way, and it can get accurate analysis results in a shorter period of time than before, so it can efficiently reduce the time cost and manpower cost.

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

NASA Astrophysics Data System (ADS)

Ferguson, Jane A.

2001-06-01

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.)

Dual-core optical fiber based strain sensor for remote sensing in hard-to-reach areas

NASA Astrophysics Data System (ADS)

MÄ kowska, Anna; Szostkiewicz, Łukasz; Kołakowska, Agnieszka; Budnicki, Dawid; Bieńkowska, Beata; Ostrowski, Łukasz; Murawski, Michał; Napierała, Marek; Mergo, Paweł; Nasiłowski, Tomasz

2017-10-01

We present research on optical fiber sensors based on microstructured multi-core fiber. Elaborated sensor can be advantageously used in hard-to-reach areas by taking advantage of the fact, that optical fibers can play both the role of sensing elements and they can realize signal delivery. By using the sensor, it is possible to increase the level of the safety in the explosive endangered areas, e.g. in mine-like objects. As a base for the strain remote sensor we use dual-core fibers. The multi-core fibers possess a characteristic parameter called crosstalk, which is a measure of the amount of signal which can pass to the adjacent core. The strain-sensitive area is made by creating the tapered section, in which the level of crosstalk is changed. Due to this fact, we present broadened conception of fiber optic sensor designing. Strain measurement is realized thanks to the fact, that depending on the strain applied, the power distribution between the cores of dual-core fibers changes. Principle of operation allows realization of measurements both in wavelength and power domain.

High-power fiber optic cable with integrated active sensors for live process monitoring

NASA Astrophysics Data System (ADS)

Blomster, Ola; Blomqvist, Mats; Bergstrand, Hans; Pålsson, Magnus

2012-03-01

In industrial applications using high-brilliance lasers at power levels up to and exceeding 20 kW and similarly direct diode lasers of 10 kW, there is an increasing demand to continuously monitor component status even in passive components such as fiber-optic cables. With fiber-optic cables designed according to the European Automotive Industry fiber standard interface there is room for integrating active sensors inside the connectors. In this paper we present the integrated active sensors in the new Optoskand QD fiber-optic cable designed to handle extreme levels of power losses, and how these sensors can be employed in industrial manufacturing. The sensors include photo diodes for detection of scattered light inside the fiber connector, absolute temperature of the fiber connector, difference in temperature of incoming and outgoing cooling water, and humidity measurement inside the fiber connector. All these sensors are connected to the fiber interlock system, where interlock break enable functions can be activated when measured signals are higher than threshold levels. It is a very fast interlock break system as the control of the signals is integrated in the electronics inside the fiber connector. Also, since all signals can be logged it is possible to evaluate what happened inside the connector before the interlock break instance. The communication to the fiber-optic connectors is via a CAN interface. Thus it is straightforward to develop the existing laser host control to also control the CAN-messages from the QD sensors.

Active Temperature Compensation Using a High-Temperature, Fiber Optic, Hybrid Pressure and Temperature Sensor

NASA Astrophysics Data System (ADS)

Fielder, Robert S.; Palmer, Matthew E.; Davis, Matthew A.; Engelbrecht, Gordon P.

2006-01-01

Luna Innovations has developed a novel, fiber optic, hybrid pressure-temperature sensor system for extremely high-temperature environments that is capable of reliable operation up to 1050 °C. This system is based on the extremely high-temperature fiber optic sensors already demonstrated during previous work. The novelty of the sensors presented here lies in the fact that pressure and temperature are measured simultaneously with a single fiber and a single transducer. This hybrid approach will enable highly accurate active temperature compensation and sensor self-diagnostics not possible with other platforms. Hybrid pressure and temperature sensors were calibrated by varying both pressure and temperature. Implementing active temperature compensation resulted in a ten-fold reduction in the temperature-dependence of the pressure measurement. Sensors were tested for operability in a relatively high neutron dose environment up to 6.9×1017 n/cm2. In addition to harsh environment survivability, fiber optic sensors offer a number of intrinsic advantages for space nuclear power applications including extremely low mass, immunity to electromagnetic interference, self diagnostics / prognostics, and smart sensor capability. Deploying fiber optic sensors on future space exploration missions would provide a substantial improvement in spacecraft instrumentation. Additional development is needed, however, before these advantages can be realized. This paper will highlight recent demonstrations of fiber optic sensors in environments relevant to space nuclear applications. Successes and lessons learned will be highlighted. Additionally, development needs will be covered which will suggest a framework for a coherent plan to continue work in this area.

A Fabry-Perot Interferometry Based MRI-Compatible Miniature Uniaxial Force Sensor for Percutaneous Needle Placement

PubMed Central

Shang, Weijian; Su, Hao; Li, Gang; Furlong, Cosme; Fischer, Gregory S.

2014-01-01

Robot-assisted surgical procedures, taking advantage of the high soft tissue contrast and real-time imaging of magnetic resonance imaging (MRI), are developing rapidly. However, it is crucial to maintain tactile force feedback in MRI-guided needle-based procedures. This paper presents a Fabry-Perot interference (FPI) based system of an MRI-compatible fiber optic sensor which has been integrated into a piezoelectrically actuated robot for prostate cancer biopsy and brachytherapy in 3T MRI scanner. The opto-electronic sensing system design was minimized to fit inside an MRI-compatible robot controller enclosure. A flexure mechanism was designed that integrates the FPI sensor fiber for measuring needle insertion force, and finite element analysis was performed for optimizing the correct force-deformation relationship. The compact, low-cost FPI sensing system was integrated into the robot and calibration was conducted. The root mean square (RMS) error of the calibration among the range of 0–10 Newton was 0.318 Newton comparing to the theoretical model which has been proven sufficient for robot control and teleoperation. PMID:25126153

Respiration and body movement analysis during sleep in bed using hetero-core fiber optic pressure sensors without constraint to human activity.

PubMed

Nishyama, Michiko; Miyamoto, Mitsuo; Watanabe, Kazuhiro

2011-01-01

We describe respiration monitoring in sleep using hetero-core fiber optic pressure sensors. The proposed hetero-core fiber optic sensor is highly sensitive to macrobending as a result of the core diameter difference due to stable single-mode transmission. Pressure sensors based on hetero-core fiber optics were fabricated to have a high sensitivity to small pressure changes resulting from minute body motions, such as respiration, during sleep and large pressure changes, such as those caused by a rollover. The sensors are installed in a conventional bed. The pressure characteristic performance of all the fabricated hetero-core fiber optic pressure sensors is found to show a monotonic response with weight changes. A respiration monitoring test in seven subjects efficiently demonstrates the effective use of eight hetero-core pressure sensors installed in a bed. Additionally, even in the case of different body postures, such as lying on one's side, a slight body movement due to respiration is detected by the hetero-core pressure sensors.

Respiration and body movement analysis during sleep in bed using hetero-core fiber optic pressure sensors without constraint to human activity

NASA Astrophysics Data System (ADS)

Nishyama, Michiko; Miyamoto, Mitsuo; Watanabe, Kazuhiro

2011-01-01

We describe respiration monitoring in sleep using hetero-core fiber optic pressure sensors. The proposed hetero-core fiber optic sensor is highly sensitive to macrobending as a result of the core diameter difference due to stable single-mode transmission. Pressure sensors based on hetero-core fiber optics were fabricated to have a high sensitivity to small pressure changes resulting from minute body motions, such as respiration, during sleep and large pressure changes, such as those caused by a rollover. The sensors are installed in a conventional bed. The pressure characteristic performance of all the fabricated hetero-core fiber optic pressure sensors is found to show a monotonic response with weight changes. A respiration monitoring test in seven subjects efficiently demonstrates the effective use of eight hetero-core pressure sensors installed in a bed. Additionally, even in the case of different body postures, such as lying on one's side, a slight body movement due to respiration is detected by the hetero-core pressure sensors.

Groove micro-structure optical fiber refractive index sensor with nanoscale gold film based on surface plasmon resonance

NASA Astrophysics Data System (ADS)

Zhang, Zhen; Li, Shuguang; Liu, Qiang; Feng, Xinxing; Zhang, Shuhuan; Wang, Yujun; Wu, Junjun

2018-07-01

A groove micro-structure optical fiber refractive index sensor with nanoscale gold film based on surface plasmon resonance (SPR) is proposed and analyzed by the finite element method (FEM). Numerical results show that the average sensitivity is 15,933 nm/refractive index unit (RIU) with the refractive index of analyte ranging from 1.40 to 1.43 and the maximum sensitivity is 28,600 nm/RIU and the resolution of the sensor is 3.50 × 10-8 RIU. The groove micro-structure optical fiber refractive index sensor do some changes on the D-shaped fiber sensor, compared with conventional D-shaped fiber sensor, it has a higher sensitivity and it is easier to produce than the traditional SPR sensor.

Fiber optic smart structures and skins V; Proceedings of the Meeting, Boston, MA, Sept. 8, 9, 1992

NASA Technical Reports Server (NTRS)

Claus, Richard O. (Editor); Rogowski, Robert S. (Editor)

1993-01-01

The present conference discusses the materials used in applications of fiber-optics (F-O) to smart structures, extrinsic Fabry-Perot interferometric F-O sensors, sapphire F-O sensors, two-mode F-O sensors with photoinduced refractive index, an F-O accelerometer using two-mode fibers, and embedded F-O acoustic sensors for flaw detection. Also discussed are an optoelectronic smart structure interface, F-O sensors for simultaneous detection of strain and temperature, an optical Mach-Zehnder interferometer for smart skins, a split-cavity cross-coupled extrinsic fiber interferometer, and an embedded Bragg grating F-O sensor for composite flexbeams, an Er-doped ring-laser strain sensor.

Electrooptic polymer voltage sensor and method of manufacture thereof

NASA Technical Reports Server (NTRS)

Gottsche, Allan (Inventor); Perry, Joseph W. (Inventor)

1993-01-01

An optical voltage sensor utilizing an electrooptic polymer is disclosed for application to electric power distribution systems. The sensor, which can be manufactured at low cost in accordance with a disclosed method, measures voltages across a greater range than prior art sensors. The electrooptic polymer, which replaces the optical crystal used in prior art sensors, is sandwiched directly between two high voltage electrodes. Voltage is measured by fiber optical means, and no voltage division is required. The sample of electrooptic polymer is fabricated in a special mold and later mounted in a sensor housing. Alternatively, mold and sensor housing may be identical. The sensor housing is made out of a machinable polymeric material and is equipped with two opposing optical windows. The optical windows are mounted in the bottom of machined holes in the wall of the mold. These holes provide for mounting of the polarizing optical components and for mounting of the fiber optic connectors. One connecting fiber is equipped with a light emitting diode as a light source. Another connecting fiber is equipped with a photodiode as a detector.

Study of Optical Fiber Sensors for Cryogenic Temperature Measurements.

PubMed

De Miguel-Soto, Veronica; Leandro, Daniel; Lopez-Aldaba, Aitor; Beato-López, Juan Jesus; Pérez-Landazábal, José Ignacio; Auguste, Jean-Louis; Jamier, Raphael; Roy, Philippe; Lopez-Amo, Manuel

2017-11-30

In this work, the performance of five different fiber optic sensors at cryogenic temperatures has been analyzed. A photonic crystal fiber Fabry-Pérot interferometer, two Sagnac interferometers, a commercial fiber Bragg grating (FBG), and a π-phase shifted fiber Bragg grating interrogated in a random distributed feedback fiber laser have been studied. Their sensitivities and resolutions as sensors for cryogenic temperatures have been compared regarding their advantages and disadvantages. Additionally, the results have been compared with the given by a commercial optical backscatter reflectometer that allowed for distributed temperature measurements of a single mode fiber.

Study of Optical Fiber Sensors for Cryogenic Temperature Measurements

PubMed Central

Leandro, Daniel; Lopez-Aldaba, Aitor; Beato-López, Juan Jesus; Pérez-Landazábal, José Ignacio; Auguste, Jean-Louis; Jamier, Raphael; Roy, Philippe; Lopez-Amo, Manuel

2017-01-01

In this work, the performance of five different fiber optic sensors at cryogenic temperatures has been analyzed. A photonic crystal fiber Fabry-Pérot interferometer, two Sagnac interferometers, a commercial fiber Bragg grating (FBG), and a π-phase shifted fiber Bragg grating interrogated in a random distributed feedback fiber laser have been studied. Their sensitivities and resolutions as sensors for cryogenic temperatures have been compared regarding their advantages and disadvantages. Additionally, the results have been compared with the given by a commercial optical backscatter reflectometer that allowed for distributed temperature measurements of a single mode fiber. PMID:29189755

Self-Reporting Fiber-Reinforced Composites That Mimic the Ability of Biological Materials to Sense and Report Damage.

PubMed

Rifaie-Graham, Omar; Apebende, Edward A; Bast, Livia K; Bruns, Nico

2018-05-01

Sensing of damage, deformation, and mechanical forces is of vital importance in many applications of fiber-reinforced polymer composites, as it allows the structural health and integrity of composite components to be monitored and microdamage to be detected before it leads to catastrophic material failure. Bioinspired and biomimetic approaches to self-sensing and self-reporting materials are reviewed. Examples include bruising coatings and bleeding composites based on dye-filled microcapsules, hollow fibers, and vascular networks. Force-induced changes in color, fluorescence, or luminescence are achieved by mechanochromic epoxy resins, or by mechanophores and force-responsive proteins located at the interface of glass/carbon fibers and polymers. Composites can also feel strain, stress, and damage through embedded optical and electrical sensors, such as fiber Bragg grating sensors, or by resistance measurements of dispersed carbon fibers and carbon nanotubes. Bioinspired composites with the ability to show autonomously if and where they have been damaged lead to a multitude of opportunities for aerospace, automotive, civil engineering, and wind-turbine applications. They range from safety features for the detection of barely visible impact damage, to the real-time monitoring of deformation of load-bearing components. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Optical fiber voltage sensors for broad temperature ranges

NASA Technical Reports Server (NTRS)

Rose, A. H.; Day, G. W.

1992-01-01

We describe the development of an optical fiber ac voltage sensor for aircraft and spacecraft applications. Among the most difficult specifications to meet for this application is a temperature stability of +/- 1 percent from -65 C to +125 C. This stability requires a careful selection of materials, components, and optical configuration with further compensation using an optical-fiber temperature sensor located near the sensing element. The sensor is a polarimetric design, based on the linear electro-optic effect in bulk Bi4Ge3O12. The temperature sensor is also polarimetric, based on the temperature dependence of the birefringence of bulk SiO2. The temperature sensor output is used to automatically adjust the calibration of the instrument.

Distributed fluorescent optical fiber proximity sensor: Towards a proof of concept

NASA Astrophysics Data System (ADS)

Gălătuș, Ramona; Faragó, Paul; Miluski, Piotr; Valles, Juan-Antonio

2018-06-01

Fluorescent fibers are optical fibers which emit light as a response to an incident phenomenon, usually an incident light. Operation depends on the doping dyes, which determine specific fluorescence and optical characteristics useful in the development of optical sensors. In this work we propose a low-cost distributed proximity sensor implemented using a red fluorescent fiber, to provide a security option for a surface plasmon resonance system. Operation of the proposed sensor relies on having the incident illumination intensity varied by the presence or absence of an obstacle in the vicinity of the sensing element. This will influence the radiated fluorescence accordingly. The proposed setup for the implementation of the optical proximity sensor assumes having a high brightness LED deployed for axial fiber illumination and a blue LED for side illumination. Electronic processing then accounts for gain and digitization. Measurement results of the prototype validate the proposed concept.

Fiber-Optic Continuous Liquid Sensor for Cryogenic Propellant Gauging

NASA Technical Reports Server (NTRS)

Xu. Wei

2010-01-01

An innovative fiber-optic sensor has been developed for low-thrust-level settled mass gauging with measurement uncertainty <0.5 percent over 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-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

New properties of a fiber optic sensor in application of a composite fence for critical infrastructure protection

NASA Astrophysics Data System (ADS)

Zyczkowski, M.; Szustakowski, M.; Markowski, P.

2015-09-01

This paper presents a new solution of using the composite fence with a novel fiber optic modalmetric sensor integrated within its structure. The modalmetric sensor is based on changes in a transverse modal field which is generated at the output of a multimode fiber. By a spatial limitation of the transverse modal field observation to its fragment thereof, changes' transformation in the modal distribution into changes of the output signal amplitude is made. Due to a constant analysis of the structure output signal, detection of an external disorder is possible. Integration of optical fibers with the fence structure allows for an accurate reproduction of the fence movement onto the optical fiber by significantly improving sensitivity of the modalmetric fiber sensor structure.

A method for the on-site determination of prestressing forces using long-gauge fiber optic strain sensors

NASA Astrophysics Data System (ADS)

Abdel-Jaber, H.; Glisic, B.

2014-07-01

Structural health monitoring (SHM) consists of the continuous or periodic measurement of structural parameters and their analysis with the aim of deducing information about the performance and health condition of a structure. The significant increase in the construction of prestressed concrete bridges motivated this research on an SHM method for the on-site determination of the distribution of prestressing forces along prestressed concrete beam structures. The estimation of the distribution of forces is important as it can give information regarding the overall performance and structural integrity of the bridge. An inadequate transfer of the designed prestressing forces to the concrete cross-section can lead to a reduced capacity of the bridge and consequently malfunction or failure at lower loads than predicted by design. This paper researches a universal method for the determination of the distribution of prestressing forces along concrete beam structures at the time of transfer of the prestressing force (e.g., at the time of prestressing or post-tensioning). The method is based on the use of long-gauge fiber optic sensors, and the sensor network is similar (practically identical) to the one used for damage identification. The method encompasses the determination of prestressing forces at both healthy and cracked cross-sections, and for the latter it can yield information about the condition of the cracks. The method is validated on-site by comparison to design forces through the application to two structures: (1) a deck-stiffened arch and (2) a curved continuous girder. The uncertainty in the determination of prestressing forces was calculated and the comparison with the design forces has shown very good agreement in most of the structures’ cross-sections, but also helped identify some unusual behaviors. The method and its validation are presented in this paper.

Fiber optic strain and temperature sensor for power plant applications

NASA Astrophysics Data System (ADS)

Narendran, Nadarajah; Weiss, Joseph M.

1996-01-01

The applicability of fiber-optic strain and temperature sensors to monitor power plant structures was evaluated on a super-heated steam pipe operating at 1000 degree(s)F at the Tennessee Valley Authority power plant in Kingston, Tennessee. The potential applications of these fiber-optic sensors include health monitoring of high-temperature structures such as boilers, tube headers, and steam pipes, as well as many other power plant structures exposed to less severe environments. The sensor selected for this application is based on a white-light interferometric technique. The key features of this sensor include its ability for absolute measurements that are not affected by light loss along the fiber cable due to, for example, microbending effects and coupler loss, its compatibility with off-the-shelf fiber-optic components, and its low cost. The glass fiber-optic strain sensors were packaged in a rugged metal housing and were spot welded to the high-temperature steam pipe. Another set of gages was placed inside a thermowell for steam temperature measurement. Data collected during a routine start-up is very encouraging and the details are presented in this manuscript.

Measurement of impulse current using polarimetric fiber optic sensor

NASA Astrophysics Data System (ADS)

Ginter, Mariusz

2017-08-01

In the paper the polarimetric current sensing solution used for measurements of high amplitude currents and short durations is presented. This type of sensor does not introduce additional resistance and inductance into the circuit, which is a desirable phenomenon in this type of measurement. The magneto element is a fiber optic coil made of spun fiber optic. The fiber in which the core is twisted around its axis is characterized by a small effect of interfering magnitudes, ie mechanical vibrations and pressure changes on the polarimeter. The presented polarimetric current sensor is completely fiber optic. Experimental results of a proposed sensor construction solution operating at 1550 nm and methods of elimination of influence values on the fiber optic current sensor were presented. The sensor was used to measure the impulse current. The generated current pulses are characterized by a duration of 23μs and amplitudes ranging from 1 to 3.5 kA. The currents in the discharge circuit are shown. The measurement uncertainty of the amplitude of the electric current in the range of measured impulses was determined and estimated to be no more than 2%.

Fiber Optic Sensor for Acoustic Detection of Partial Discharges in Oil-Paper Insulated Electrical Systems

PubMed Central

Posada-Roman, Julio; Garcia-Souto, Jose A.; Rubio-Serrano, Jesus

2012-01-01

A fiber optic interferometric sensor with an intrinsic transducer along a length of the fiber is presented for ultrasound measurements of the acoustic emission from partial discharges inside oil-filled power apparatus. The sensor is designed for high sensitivity measurements in a harsh electromagnetic field environment, with wide temperature changes and immersion in oil. It allows enough sensitivity for the application, for which the acoustic pressure is in the range of units of Pa at a frequency of 150 kHz. In addition, the accessibility to the sensing region is guaranteed by immune fiber-optic cables and the optical phase sensor output. The sensor design is a compact and rugged coil of fiber. In addition to a complete calibration, the in-situ results show that two types of partial discharges are measured through their acoustic emissions with the sensor immersed in oil. PMID:22666058

Monitoring system of hydraulic lifting device based on the fiber optic sensors

NASA Astrophysics Data System (ADS)

Fajkus, Marcel; Nedoma, Jan; Novak, Martin; Martinek, Radek; Vanus, Jan; Mec, Pavel; Vasinek, Vladimir

2017-10-01

This article deals with the description of the monitoring system of hydraulic lifting device based on the fiber-optic sensors. For minimize the financial costs of the proposed monitoring system, the power evaluation of measured signal has been chosen. The solution is based on an evaluation of the signal obtained using the single point optic fiber sensors with overlapping reflective spectra. For encapsulation of the sensors was used polydimethylsiloxane (PDMS) polymer. To obtain a information of loading is uses the action of deformation of the lifting device on the pair single point optic fiber sensors mounted on the lifting device of the tested car. According to the proposed algorithm is determined information of pressure with an accuracy of +/- 5 %. Verification of the proposed system was realized on the various types of the tested car with different loading. The original contribution of the paper is to verify the new low-cost system for monitoring the hydraulic lifting device based on the fiber-optic sensors.

High speed demodulation systems for fiber optic grating sensors

NASA Technical Reports Server (NTRS)

Udd, Eric (Inventor); Weisshaar, Andreas (Inventor)

2002-01-01

Fiber optic grating sensor demodulation systems are described that offer high speed and multiplexing options for both single and multiple parameter fiber optic grating sensors. To attain very high speeds for single parameter fiber grating sensors ratio techniques are used that allow a series of sensors to be placed in a single fiber while retaining high speed capability. These methods can be extended to multiparameter fiber grating sensors. Optimization of speeds can be obtained by minimizing the number of spectral peaks that must be processed and it is shown that two or three spectral peak measurements may in specific multiparameter applications offer comparable or better performance than processing four spectral peaks. Combining the ratio methods with minimization of peak measurements allows very high speed measurement of such important environmental effects as transverse strain and pressure.

Micro optical fiber light source and sensor and method of fabrication thereof

DOEpatents

Kopelman, Raoul; Tan, Weihong; Shi, Zhong-You

1997-01-01

This invention relates generally to the development of and a method of fabricating a fiber optic micro-light source and sensor (50). An optical fiber micro-light source (50) is presented whose aperture is extremely small yet able to act as an intense light source. Light sources of this type have wide ranging applications, including use as micro-sensors (22) in NSOM. Micro-sensor light sources have excellent detection limits as well as photo stability, reversibility, and millisecond response times. Furthermore, a method for manufacturing a micro optical fiber light source is provided. It involves the photo-chemical attachment of an optically active material onto the end surface of an optical fiber cable which has been pulled to form an end with an extremely narrow aperture. More specifically, photopolymerization has been applied as a means to photo-chemically attach an optically active material (60). This process allows significant control of the size of the micro light source (50). Furthermore, photo-chemically attaching an optically active material (60) enables the implementation of the micro-light source in a variety of sensor applications.

Micro optical fiber light source and sensor and method of fabrication thereof

DOEpatents

Kopelman, R.; Tan, W.; Shi, Z.Y.

1997-05-06

This invention relates generally to the development of and a method of fabricating a fiber optic micro-light source and sensor. An optical fiber micro-light source is presented whose aperture is extremely small yet able to act as an intense light source. Light sources of this type have wide ranging applications, including use as micro-sensors in NSOM. Micro-sensor light sources have excellent detection limits as well as photo stability, reversibility, and millisecond response times. Furthermore, a method for manufacturing a micro optical fiber light source is provided. It involves the photo-chemical attachment of an optically active material onto the end surface of an optical fiber cable which has been pulled to form an end with an extremely narrow aperture. More specifically, photopolymerization has been applied as a means to photo-chemically attach an optically active material. This process allows significant control of the size of the micro light source. Furthermore, photo-chemically attaching an optically active material enables the implementation of the micro-light source in a variety of sensor applications. 10 figs.

Smart Microsystems with Photonic Element and Their Applications to Aerospace Platforms

NASA Technical Reports Server (NTRS)

Adamovsky, G.; Lekki, J.; Sutter, J. K.; Sarkisov, S. S.; Curley, M. J.; Martin, C. E.

2000-01-01

The need to make manufacturing, operation, and support of airborne vehicles safer and more efficient forces engineers and scientists to look for lighter, cheaper, more reliable technologies. Light weight, immunity to EMI, fire safety, high bandwidth, and high signal fidelity have already made photonics in general and fiber optics in particular an extremely attractive medium for communication purposes. With the fiber optics serving as a central nervous system of the vehicle, generation, detection, and processing of the signal occurs at the peripherals that include smart structures and devices. Due to their interdisciplinary nature, photonic technologies cover such diverse areas as optical sensors and actuators, embedded and distributed sensors, sensing schemes and architectures, harnesses and connectors, signal processing and algorithms. The paper includes a brief description of work in the photonic area that is going on at NASA, especially at the Glenn Research Center (GRC).

Microelectromechanical system pressure sensor integrated onto optical fiber by anodic bonding.

PubMed

Saran, Anish; Abeysinghe, Don C; Boyd, Joseph T

2006-03-10

Optical microelectromechanical system pressure sensors based on the principle of Fabry-Perot interferometry have been developed and fabricated using the technique of silicon-to-silicon anodic bonding. The pressure sensor is then integrated onto an optical fiber by a novel technique of anodic bonding without use of any adhesives. In this anodic bonding technique we use ultrathin silicon of thickness 10 microm to bond the optical fiber to the sensor head. The ultrathin silicon plays the role of a stress-reducing layer, which helps the bonding of an optical fiber to silicon having conventional wafer thickness. The pressure-sensing membrane is formed by 8 microm thick ultrathin silicon acting as a membrane, thus eliminating the need for bulk silicon etching. The pressure sensor integrated onto an optical fiber is tested for static response, and experimental results indicate degradation in the fringe visibility of the Fabry-Perot interferometer. This effect was mainly due to divergent light rays from the fiber degrading the fringe visibility. This effect is demonstrated in brief by an analytical model.

Temperature measurement and damage detection in concrete beams exposed to fire using PPP-BOTDA based fiber optic sensors

NASA Astrophysics Data System (ADS)

Bao, Yi; Hoehler, Matthew S.; Smith, Christopher M.; Bundy, Matthew; Chen, Genda

2017-10-01

In this study, Brillouin scattering-based distributed fiber optic sensor is implemented to measure temperature distributions and detect cracks in concrete structures subjected to fire for the first time. A telecommunication-grade optical fiber is characterized as a high temperature sensor with pulse pre-pump Brillouin optical time domain analysis (PPP-BODTA), and implemented to measure spatially-distributed temperatures in reinforced concrete beams in fire. Four beams were tested to failure in a natural gas fueled compartment fire, each instrumented with one fused silica, single-mode optical fiber as a distributed sensor and four thermocouples. Prior to concrete cracking, the distributed temperature was validated at locations of the thermocouples by a relative difference of less than 9%. The cracks in concrete can be identified as sharp peaks in the temperature distribution since the cracks are locally filled with hot air. Concrete cracking did not affect the sensitivity of the distributed sensor but concrete spalling broke the optical fiber loop required for PPP-BOTDA measurements.

Optical fiber pressure and acceleration sensor fabricated on a fiber endface

DOEpatents

Zhu, Yizheng; Wang, Xingwei; Xu, Juncheng; Wang, Anbo

2006-05-30

A fiber optic sensor has a hollow tube bonded to the endface of an optical fiber, and a diaphragm bonded to the hollow tube. The fiber endface and diaphragm comprise an etalon cavity. The length of the etalon cavity changes when applied pressure or acceleration flexes the diaphragm. The entire structure can be made of fused silica. The fiber, tube, and diaphragm can be bonded with a fusion splice. The present sensor is particularly well suited for measuring pressure or acceleration in high temperature, high pressure and corrosive environments (e.g., oil well downholes and jet engines). The present sensors are also suitable for use in biological and medical applications.

High-precision micro-displacement optical-fiber sensor based on surface plasmon resonance.

PubMed

Zhu, Zongda; Liu, Lu; Liu, Zhihai; Zhang, Yu; Zhang, Yaxun

2017-05-15

We propose and demonstrate a novel optical-fiber micro-displacement sensor based on surface plasmon resonance (SPR) by fabricating a Kretschmann configuration on graded-index multimode fiber (GIMMF). We employ a single-mode fiber to change the radial position of the incident beam as the displacement. In the GIMMF, the angle between the light beam and fiber axis, which is closely related to the resonance angle, is changed by the displacement; thus, the resonance wavelength of the fiber SPR shifts. This micro-displacement fiber sensor has a wide detection range of 0-25 μm, a high sensitivity with maximum up to 10.32 nm/μm, and a nanometer resolution with minimum to 2 nm, which transcends almost all of other optical-fiber micro-displacement sensors. In addition, we also research that increasing the fiber polishing angle or medium refractive index can improve the sensitivity. This micro-displacement sensor will have a great significance in many industrial applications and provide a neoteric, rapid, and accurate optical measurement method in micro-displacement.

Nanoparticles based fiber optic SPR sensor

NASA Astrophysics Data System (ADS)

Shah, Kruti; Sharma, Navneet K.

2018-05-01

Localized surface plasmon resonance based fiber optic sensor using platinum nanoparticles is proposed and theoretically analyzed. Increase in thickness of nanoparticles layer increases the sensitivity of sensor. 50 nm thick platinum nanoparticles layer based sensor reveals highest sensitivity.

Planar location of the simulative acoustic source based on fiber optic sensor array

NASA Astrophysics Data System (ADS)

Liang, Yi-Jun; Liu, Jun-feng; Zhang, Qiao-ping; Mu, Lin-lin

2010-06-01

A fiber optic sensor array which is structured by four Sagnac fiber optic sensors is proposed to detect and locate a simulative source of acoustic emission (AE). The sensing loops of Sagnac interferometer (SI) are regarded as point sensors as their small size. Based on the derived output light intensity expression of SI, the optimum work condition of the Sagnac fiber optic sensor is discussed through the simulation of MATLAB. Four sensors are respectively placed on a steel plate to structure the sensor array and the location algorithms are expatiated. When an impact is generated by an artificial AE source at any position of the plate, the AE signal will be detected by four sensors at different times. With the help of a single chip microcomputer (SCM) which can calculate the position of the AE source and display it on LED, we have implemented an intelligent detection and location.

Erbium-doped fiber amplifier elements for structural analysis sensors

NASA Technical Reports Server (NTRS)

Hanna-Hawver, P.; Kamdar, K. D.; Mehta, S.; Nagarajan, S.; Nasta, M. H.; Claus, R. O.

1992-01-01

The use of erbium-doped fiber amplifiers (EDFA's) in optical fiber sensor systems for structural analysis is described. EDFA's were developed for primary applications as periodic regenerator amplifiers in long-distance fiber-based communication systems. Their in-line amplification performance also makes them attractive for optical fiber sensor systems which require long effective lengths or the synthesis of special length-dependent signal processing functions. Sensor geometries incorporating EDFA's in recirculating and multiple loop sensors are discussed. Noise and polarization birefringence are also considered, and the experimental development of system components is discussed.

Evaluation of Fiber Bragg Grating and Distributed Optical Fiber Temperature Sensors

DOE Office of Scientific and Technical Information (OSTI.GOV)

McCary, Kelly Marie

Fiber optic temperature sensors were evaluated in the High Temperature Test Lab (HTTL) to determine the accuracy of the measurements at various temperatures. A distributed temperature sensor was evaluated up to 550C and a fiber Bragg grating sensor was evaluated up to 750C. HTTL measurements indicate that there is a drift in fiber Bragg sensor over time of approximately -10C with higher accuracy at temperatures above 300C. The distributed sensor produced some bad data points at and above 500C but produced measurements with less than 2% error at increasing temperatures up to 400C

High spatial resolution fiber optical sensors for simultaneous temperature and chemical sensing for energy industries

NASA Astrophysics Data System (ADS)

Yan, Aidong; Huang, Sheng; Li, Shuo; Zaghloul, Mohamed; Ohodnicki, Paul; Buric, Michael; Chen, Kevin P.

2017-05-01

This paper demonstrates optical fibers as high-temperature sensor platforms. Through engineering and onfiber integration of functional metal oxide sensory materials, we report the development of an integrated sensor solution to perform temperature and chemical measurements for high-temperature energy applications. Using the Rayleigh optical frequency domain reflectometry (OFDR) distributed sensing scheme, the temperature and hydrogen concentration were measured along the fiber. To overcome the weak Rayleighbackscattering intensity exhibited by conventional optical fibers, an ultrafast laser was used to enhance the Rayleigh scattering by a direct laser writing method. Using the Rayleigh-enhanced fiber as sensor platform, both temperature and hydrogen reaction were monitored at high temperature up to 750°C with 4-mm spatial resolution.

Magneto-Optic Field Coupling in Optical Fiber Bragg Gratings

NASA Technical Reports Server (NTRS)

Carman, Gregory P. (Inventor); Mohanchandra, Panduranga K. (Inventor); Emmons, Michael C. (Inventor); Richards, William Lance (Inventor)

2016-01-01

The invention is a magneto-optic coupled magnetic sensor that comprises a standard optical fiber Bragg grating system. The system includes an optical fiber with at least one Bragg grating therein. The optical fiber has at least an inner core and a cladding that surrounds the inner core. The optical fiber is part of an optical system that includes an interrogation device that provides a light wave through the optical fiber and a system to determine the change in the index of refraction of the optical fiber. The cladding of the optical fiber comprises at least a portion of which is made up of ferromagnetic particles so that the ferromagnetic particles are subject to the light wave provided by the interrogation system. When a magnetic field is present, the ferromagnetic particles change the optical properties of the sensor directly.

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

PubMed Central

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

2014-01-01

Optical fibers have been involved in the area of sensing applications for more than four decades. Moreover, interferometric optical fiber sensors have attracted broad interest for their prospective applications in sensing temperature, refractive index, strain measurement, pressure, acoustic wave, vibration, magnetic field, and voltage. During this time, numerous types of interferometers have been developed such as Fabry-Perot, Michelson, Mach-Zehnder, Sagnac Fiber, and Common-path interferometers. Fabry-Perot interferometer (FPI) fiber-optic sensors have been extensively investigated for their exceedingly effective, simple fabrication as well as low cost aspects. In this study, a wide variety of FPI sensors are reviewed in terms of fabrication methods, principle of operation and their sensing applications. The chronology of the development of FPI sensors and their implementation in various applications are discussed. PMID:24763250

Advanced Interrogation of Fiber-Optic Bragg Grating and Fabry-Perot Sensors with KLT Analysis

PubMed Central

Tosi, Daniele

2015-01-01

The Karhunen-Loeve Transform (KLT) is applied to accurate detection of optical fiber sensors in the spectral domain. By processing an optical spectrum, although coarsely sampled, through the KLT, and subsequently processing the obtained eigenvalues, it is possible to decode a plurality of optical sensor results. The KLT returns higher accuracy than other demodulation techniques, despite coarse sampling, and exhibits higher resilience to noise. Three case studies of KLT-based processing are presented, representing most of the current challenges in optical fiber sensing: (1) demodulation of individual sensors, such as Fiber Bragg Gratings (FBGs) and Fabry-Perot Interferometers (FPIs); (2) demodulation of dual (FBG/FPI) sensors; (3) application of reverse KLT to isolate different sensors operating on the same spectrum. A simulative outline is provided to demonstrate the KLT operation and estimate performance; a brief experimental section is also provided to validate accurate FBG and FPI decoding. PMID:26528975

Advanced Interrogation of Fiber-Optic Bragg Grating and Fabry-Perot Sensors with KLT Analysis.

PubMed

Tosi, Daniele

2015-10-29

The Karhunen-Loeve Transform (KLT) is applied to accurate detection of optical fiber sensors in the spectral domain. By processing an optical spectrum, although coarsely sampled, through the KLT, and subsequently processing the obtained eigenvalues, it is possible to decode a plurality of optical sensor results. The KLT returns higher accuracy than other demodulation techniques, despite coarse sampling, and exhibits higher resilience to noise. Three case studies of KLT-based processing are presented, representing most of the current challenges in optical fiber sensing: (1) demodulation of individual sensors, such as Fiber Bragg Gratings (FBGs) and Fabry-Perot Interferometers (FPIs); (2) demodulation of dual (FBG/FPI) sensors; (3) application of reverse KLT to isolate different sensors operating on the same spectrum. A simulative outline is provided to demonstrate the KLT operation and estimate performance; a brief experimental section is also provided to validate accurate FBG and FPI decoding.

New intravascular flow sensor using fiber optics

NASA Astrophysics Data System (ADS)

Stenow, Erik N. D.

1994-12-01

A new sensor using fiber optics is suggested for blood flow measurements in small vessels. The sensor principle and a first evaluation on a flow model are presented. The new sensor uses small CO2 gas bubbles as flow markers for optical detection. When the bubbles pass an optical window, light emitted from one fiber is reflected and scattered into another fiber. The sensor has been proven to work in a 3 mm flow model using two 110 micrometers optical fibers and a 100 micrometers steel capillary inserted into a 1 mm guide wire. The evaluation of a sensor archetype shows that the new sensor provides a promising method for intravascular blood flow measurement in small vessels. The linearity for steady state flow is studied in the flow interval 30 - 130 ml/min. comparison with ultrasound Doppler flowmetry was performed for pulsatile flow in the interval 25 - 125 ml/min. with a pulse length between 0.5 and 2 s. The use of intravascular administered CO2 in small volumes is harmless because the gas is rapidly dissolved in whole blood.

Sensitive liquid refractive index sensors using tapered optical fiber tips.

PubMed

Tai, Yi-Hsin; Wei, Pei-Kuen

2010-04-01

An optical fiber sensor based on the change of optical confinement in a subwavelength tip is presented. The optical spot is substantially increased when the environmental refractive index (RI) increases from 1.3 to 1.4. By measuring the intensity of low angular spectral components, an intensity sensitivity up to 8000% per RI unit is achieved. The fiber tip sensors take advantage of the small detection volume and real-time responses. We demonstrate the application of the nanofiber sensors for measuring concentrations of acids and evaporation rates of aqueous mixtures.

Optical fiber humidity sensor based on evanescent-wave scattering.

PubMed

Xu, Lina; Fanguy, Joseph C; Soni, Krunal; Tao, Shiquan

2004-06-01

The phenomenon of evanescent-wave scattering (EWS) is used to design an optical-fiber humidity sensor. Porous solgel silica (PSGS) coated on the surface of a silica optical-fiber core scatters evanescent waves that penetrate the coating layer. Water molecules in the gas phase surrounding the optical fiber can be absorbed into the inner surface of the pores of the porous silica. The absorbed water molecules form a thin layer of liquid water on the inner surface of the porous silica and enhance the EWS. The amount of water absorbed into the PSGS coating is in dynamic equilibrium with the water-vapor pressure in the gas phase. Therefore the humidity in the air can be quantitatively determined with fiber-optic EWS caused by the PSGS coating. The humidity sensor reported here is fast in response, reversible, and has a wide dynamic range. The possible interference caused by EWS to an optical-fiber gas sensor with a reagent-doped PSGS coating as a transducer is also discussed.

Optical fiber sensors based on nanostructured coatings fabricated by means of the layer-by-layer electrostatic self-assembly method

NASA Astrophysics Data System (ADS)

Arregui, Francisco J.; Matías, Ignacio R.; Claus, Richard O.

2007-07-01

The Layer-by-Layer Electrostatic Self-Assembly (ESA) method has been successfully used for the design and fabrication of nanostructured materials. More specifically, this technique has been applied for the deposition of thin films on optical fibers with the purpose of fabricating different types of optical fiber sensors. In fact, optical fiber sensors for measuring humidity, temperature, pH, hydrogen peroxide, glucose, volatile organic compounds or even gluten have been already experimentally demonstrated. The versatility of this technique allows the deposition of these sensing coatings on flat substrates and complex geometries as well. For instance, nanoFabry-Perots and microgratings have been formed on cleaved ends of optical fibers (flat surfaces) and also sensing coatings have been built onto long period gratings (cylindrical shape), tapered fiber ends (conical shape), biconically tapered fibers or even the internal side of hollow core fibers. Among the different materials used for the construction of these sensing nanostructured coatings, diverse types such as polymers, inorganic semiconductors, colorimetric indicators, fluorescent dyes, quantum dots or even biological elements as enzymes can be found. This technique opens the door to the fabrication of new types of optical fiber sensors.

A micro S-shaped optical fiber temperature sensor based on dislocation fiber splice

NASA Astrophysics Data System (ADS)

Yan, Haitao; Li, Pengfei; Zhang, Haojie; Shen, Xiaoyue; Wang, Yongzhen

2017-12-01

We fabricated a simple, compact, and stable temperature sensor based on an S-shaped dislocated optical fiber. The dislocation optical fiber has two splice points, and we obtained the optimal parameters based on the theory and our experiment, such as the dislocation amount and length of the dislocation optical fiber. According to the relationship between the temperature and the peak wavelength shift, the temperature of the environment can be obtained. Then, we made this fiber a micro bending as S-shape between the two dislocation points, and the S-shaped micro bending part could release stress with the change in temperature and reduce the effect of stress on the temperature measurement. This structure could solve the problem of sensor distortion caused by the cross response of temperature and stress. We measured the S-shaped dislocation fiber sensor and the dislocation fiber without S-shape under the same environment and conditions, and the S-shaped dislocation fiber had the advantages of the stable reliability and good linearity.

Intensity insensitive one-dimensional optical fiber tilt sensor

NASA Astrophysics Data System (ADS)

Vadakkapattu Canthadai, Badrinath; Sengupta, Dipankar; Pachava, Vengalrao; Kishore, P.

2014-06-01

The paper presents a proximity sensor based on plastic optical fiber as tilt sensor. Discrete and continuous response of the sensor against change in tilt angle of the setup is studied. The sensor can detect tilt angles up to 5.70 and the achieved sensor sensitivity is 97mV/0 .

Bolt Shear Force Sensor

DTIC Science & Technology

2015-03-12

submarine and ship systems required to survive the effects of mechanical shock must consider not only the system and foundation to which the system...See FIG. 1). In the figure, a Bragg grating sensor 1 is inserted and held by epoxy 2 in a mechanical fastener 10. Optical fiber 3 connects the...circumferential) strains. The sensing elements 120 are fixedly bonded to the vertical section 103 using conventional adhesives such as epoxies or

Fiber Sensor Systems Based on Fiber Laser and Microwave Photonic Technologies

PubMed Central

Fu, Hongyan; Chen, Daru; Cai, Zhiping

2012-01-01

Fiber-optic sensors, especially fiber Bragg grating (FBG) sensors are very attractive due to their numerous advantages over traditional sensors, such as light weight, high sensitivity, cost-effectiveness, immunity to electromagnetic interference, ease of multiplexing and so on. Therefore, fiber-optic sensors have been intensively studied during the last several decades. Nowadays, with the development of novel fiber technology, more and more newly invented fiber technologies bring better and superior performance to fiber-optic sensing networks. In this paper, the applications of some advanced photonic technologies including fiber lasers and microwave photonic technologies for fiber sensing applications are reviewed. FBG interrogations based on several kinds of fiber lasers, especially the novel Fourier domain mode locking fiber laser, have been introduced; for the application of microwave photonic technology, examples of microwave photonic filtering utilized as a FBG sensing interrogator and microwave signal generation acting as a transversal loading sensor have been given. Both theoretical analysis and experimental demonstrations have been carried out. The comparison of these advanced photonic technologies for the applications of fiber sensing is carried out and important issues related to the applications have been addressed and the suitable and potential application examples have also been discussed in this paper. PMID:22778591

Flight testing of a fiber optic temperature sensor

NASA Technical Reports Server (NTRS)

Finney, M. J.; Tregay, G. W.; Calabrese, P. R.

1993-01-01

A fiber optic temperature sensor (FOTS) system consisting of an optical probe, a flexible fiber optic cable, and an electro-optic signal processor was fabricated to measure the gas temperature in a turbine engine. The optical probe contained an emissive source embedded in a sapphire lightguide coupled to a fiber-optic jumper cable and was retrofitted into an existing thermocouple probe housing. The flexible fiber optic cable was constructed with 200 micron core, polyimide-coated fiber and was ruggedized for an aircraft environment. The electro-optic signal processing unit was used to ratio the intensities of two wavelength intervals and provided an analog output value of the indicated temperature. Subsequently, this optical sensor system was installed on a NASA Dryden F-15 Highly Integrated Digital Electronic Control (HIDEC) Aircraft Engine and several flight tests were conducted. Over the course of flight testing, the FOTS system's response was proportional to the average of the existing thermocouples sensing the changes in turbine engine thermal conditions.

High-sensitivity fiber optic acoustic sensors

NASA Astrophysics Data System (ADS)

Lu, Ping; Liu, Deming; Liao, Hao

2016-11-01

Due to the overwhelming advantages compared with traditional electronicsensors, fiber-optic acoustic sensors have arisen enormous interest in multiple disciplines. In this paper we present the recent research achievements of our group on fiber-optic acoustic sensors. The main point of our research is high sensitivity interferometric acoustic sensors, including Michelson, Sagnac, and Fabry-Pérot interferometers. In addition, some advanced technologies have been proposed for acoustic or acoustic pressure sensing such as single-mode/multimode fiber coupler, dual FBGs and multi-longitudinal mode fiber laser based acoustic sensors. Moreover, our attention we have also been paid on signal demodulation schemes. The intensity-based quadrature point (Q-point) demodulation, two-wavelength quadrature demodulation and symmetric 3×3 coupler methodare discussed and compared in this paper.

Bio-optical sensor for brain activity measurement based on whispering gallery modes

NASA Astrophysics Data System (ADS)

Ali, Amir R.; Massoud, Yasmin M.

2017-05-01

In this paper, a high-resolution bio-optical sensor is developed for brain activity measurement. The aim is to develop an optical sensor with enough sensitivity to detect small electric field perturbations caused by neuronal action potential. The sensing element is a polymeric dielectric micro-resonator fabricated in a spherical shape with a few hundred microns in diameter. They are made of optical quality polymers that are soft which make them mechanically compatible with tissue. The sensors are attached to or embedded in optical fibers which serve as input/output conduits for the sensors. Hundreds or even thousands of spheres can be attached to a single fiber to detect and transmit signals at different locations. The high quality factor for the optical resonator makes it significantly used in such bio-medical applications. The sensing phenomenon is based on whispering gallery modes (WGM) shifts of the optical sensor. To mimic the brain signals, the spherical resonator is immersed in a homogeneous electrical field that is created by applying potential difference across two metallic plates. One of the plates has a variable voltage while the volt on the other plate kept fixed. Any small perturbations of the potential difference (voltage) lead to change in the electric field intensity. In turn the sensor morphology will be affected due to the change in the electrostriction force acting on it causing change in its WGM. By tracking these WGM shift on the transmission spectrum, the induced potential difference (voltage change) could be measured. Results of a mathematical model simulation agree well with the preliminary experiments. Also, the results show that the brain activity could be measured using this principle.

A fiber optic temperature sensor based on the combination of epoxy and glass particles with different thermo-optic coefficients

NASA Astrophysics Data System (ADS)

Wildner, Wolfgang; Drummer, Dietmar

2016-12-01

This paper describes the development and function of an optical fiber temperature sensor made out of a compound of epoxy and optical glass particles. Because of the different thermo-optic coefficients of these materials, this compound exhibits a strong wavelength and temperature dependent optical transmission, and it therefore can be employed for fiber optic temperature measurements. The temperature at the sensor, which is integrated into a polymer optical fiber (POF), is evaluated by the ratio of the transmitted intensity of two different light-emitting diodes (LED) with a wavelength of 460 nm and 650 nm. The material characterization and influences of different sensor lengths and two particle sizes on the measurement result are discussed. The temperature dependency of the transmission increases with smaller particles and with increasing sensor length. With glass particles with a diameter of 43 μm and a sensor length of 9.8 mm, the intensity ratio of the two LEDs decreases by 60% within a temperature change from 10°C to 40°C.

Optical fiber sensor based on a polymer optical fiber macro-bend to study thermal expansion of metals

NASA Astrophysics Data System (ADS)

Pakdeevanich, Paradorn

2018-05-01

Thermal expansion is an important parameter for characterization of metals. As metal is heated, the molecules vibrate more violently and expand in all direction. Investigators have focused to study the thermal strain. However, the amount of expansion is difficult to measure. An attempt has been made to develop an apparatus using optical technique. The principle of this system is the transformation of length changes into changes of light intensity. The purpose of this work is to design and develop an optical fiber sensor based on a macro-bend of a polymer optical fiber. In this system, thermal expansion of metal was converted into the rolling of a needle in which placed beneath a flat bar of metal. Optical fiber sensor was attached to the ended section of a needle. As the crimp tube of the fiber sensor was moved due to thermal expansion of metal, the bend radii of optical fiber sensor was changed. As a sequence, the loss induced by the bending effect was depended on the expansion of metal that changed with temperature. In this study, we utilized optical fiber sensor to monitor and compare the thermal expansion of copper, brass and aluminum. According to our experimental results, the linear response with temperature was reported. The measured values of coefficient of thermal expansion was analyzed to be 0.45, 0.35 and 0.32 a.u./°C for aluminum bar, brass bar and copper bar, respectively. In addition, the effect of the size of the diameter of a needle on the response of bending loss was investigated.

Fourier transform infrared (FTIR) fiber optic monitoring of composites during cure in an autoclave

NASA Technical Reports Server (NTRS)

Druy, Mark A.; Elandjian, Lucy; Stevenson, William A.; Driver, Richard D.; Leskowitz, Garett M.

1990-01-01

Real-time in situ monitoring of the chemical states of epoxy resins was investigated during cure in an autoclave using infrared evanescent spectroscopy. Fiber evanescent sensors were developed which may be sandwiched between the plies of the prepreg sample. A short length of sapphire fiber was used as the sensor cell portion of the fiber probe. Heavy metal fluoride glass optical fiber cables were designed for connecting the FTIR spectrometer to the sensor fiber within the autoclave. The sapphire fibers have outstanding mechanical thermal properties which should permit their use as an embedded link in all thermoset composites. The system is capable of operation at a temperature of 250 C for periods up to 8 hours without major changes to the fiber transmission. A discussion of the selection of suitable sensor fibers, the construction of a fiber-optic interface, and the interpretation of in situ infrared spectra of the curing process is presented.

Apparatus for weighing and identifying characteristics of a moving vehicle

DOEpatents

Muhs, Jeffrey D.; Jordan, John K.; Tobin, Jr., Kenneth W.; LaForge, John V.

1993-01-01

Apparatus for weighing a vehicle in motion is provided by employing a plurality of elongated fiber-optic sensors defined by an optical fiber embedded in an encasement of elastomeric material and disposed parallel to each other on the roadway in the path of moving vehicles. Each fiber-optic sensor is provided with contact grid means which can be selectively altered to provide the fiber-optic sensors with sensitivities to vehicular weight different from each other for weighing vehicles in an extended weight range. Switch means are used in conjunction with the fiber-optic sensors to provide signals indicative of the speed of the moving vehicle, the number of axles on the vehicle, weight distribution, tire position, and the wheelbase of the vehicle. The use of a generally N-shaped configuration of switch means also provides a determination of the number of tires on each axle and the tire footprint. When switch means in this configuration are formed of optical fibers, the extent of light transmission through the fibers during contact with the tires of the vehicle is indicative of the vehicle weight.

Apparatus for weighing and identifying characteristics of a moving vehicle

DOEpatents

Muhs, J.D.; Jordan, J.K.; Tobin, K.W. Jr.; LaForge, J.V.

1993-11-09

Apparatus for weighing a vehicle in motion is provided by employing a plurality of elongated fiber-optic sensors defined by an optical fiber embedded in an encasement of elastomeric material and disposed parallel to each other on the roadway in the path of moving vehicles. Each fiber-optic sensor is provided with contact grid means which can be selectively altered to provide the fiber-optic sensors with sensitivities to vehicular weight different from each other for weighing vehicles in an extended weight range. Switch means are used in conjunction with the fiber-optic sensors to provide signals indicative of the speed of the moving vehicle, the number of axles on the vehicle, weight distribution, tire position, and the wheelbase of the vehicle. The use of a generally N-shaped configuration of switch means also provides a determination of the number of tires on each axle and the tire footprint. When switch means in this configuration are formed of optical fibers, the extent of light transmission through the fibers during contact with the tires of the vehicle is indicative of the vehicle weight. 15 figures.

Hybrid Raman/Brillouin-optical-time-domain-analysis-distributed optical fiber sensors based on cyclic pulse coding.

PubMed

Taki, M; Signorini, A; Oton, C J; Nannipieri, T; Di Pasquale, F

2013-10-15

We experimentally demonstrate the use of cyclic pulse coding for distributed strain and temperature measurements in hybrid Raman/Brillouin optical time-domain analysis (BOTDA) optical fiber sensors. The highly integrated proposed solution effectively addresses the strain/temperature cross-sensitivity issue affecting standard BOTDA sensors, allowing for simultaneous meter-scale strain and temperature measurements over 10 km of standard single mode fiber using a single narrowband laser source only.

Fiber optic sensor based on reflectivity configurations to detect heart rate

NASA Astrophysics Data System (ADS)

Yunianto, M.; Marzuki, A.; Riyatun, R.; Lestari, D.

2016-11-01

Research of optical fiber-based heart rate detection sensor has been conducted using the reflection configurationon the thorax motion modified. Optical fiber used in this research was Plastic Optical Fiber (POF) with a diameter of 0.5. Optical fiber system is made with two pieces of fiber, the first fiber is to serve as a transmitter transmitting light from the source to the reflector membrane, the second fiber serves as a receiver. One of the endsfrom the two fibersis pressed and positioned perpendicular of reflector membrane which is placed on the surface of the chest. The sensor works on the principle of intensity changes captured by the receiver fiber when the reflector membrane gets the vibe from the heart. The light source used is in the form of Light Emitting Diode (LED) and Light Dependent Resistor (LDR) as a light sensor. Variations are performed on the reflector membrane diameter. The light intensity received by the detector increases along with the increasing width of the reflector membrane diameter. The results show that this sensor can detect the harmonic peak at a frequency of 1.5 Hz; 7.5 Hz; 10.5 Hz; and 22.5 Hz in a healthy human heart with an average value of Beat Per Minute (BPM) by 78 times, a prototype sensor that is made can work and function properly.

Residual strain sensor using Al-packaged optical fiber and Brillouin optical correlation domain analysis.

PubMed

Choi, Bo-Hun; Kwon, Il-Bum

2015-03-09

We propose a distributed residual strain sensor that uses an Al-packaged optical fiber for the first time. The residual strain which causes Brillouin frequency shifts in the optical fiber was measured using Brillouin optical correlation domain analysis with 2 cm spatial resolution. We quantified the Brillouin frequency shifts in the Al-packaged optical fiber by the tensile stress and compared them for a varying number of Al layers in the optical fiber. The Brillouin frequency shift of an optical fiber with one Al layer had a slope of 0.038 MHz/με with respect to tensile stress, which corresponds to 78% of that for an optical fiber without Al layers. After removal of the stress, 87% of the strain remained as residual strain. When different tensile stresses were randomly applied, the strain caused by the highest stress was the only one detected as residual strain. The residual strain was repeatedly measured for a time span of nine months for the purpose of reliability testing, and there was no change in the strain except for a 4% reduction, which is within the error tolerance of the experiment. A composite material plate equipped with our proposed Al-packaged optical fiber sensor was hammered for impact experiment and the residual strain in the plate was successfully detected. We suggest that the Al-packaged optical fiber can be adapted as a distributed strain sensor for smart structures, including aerospace structures.

Evaluation of Aerogel Clad Optical Fibers Final Report CRADA No. TSB-1448-97

DOE Office of Scientific and Technical Information (OSTI.GOV)

Maitland, Duncan; Droege, M. W.

Fiber-optic based sensors will be needed for in situ monitoring of degradation products in various components of nuclear weapons. These sensors typically consist of a transducer located at the measurement site whose optical properties are modulated by interaction with the targeted degradation product. The interrogating light source and the detector for determining sensor response are located remotely. These two subsystems are connected by fiber optic cables. LLNL has developed a new technology, aerogel clad optical fibers, that have the advantage of accepting incident rays over a much wider angular range than normal glass clad fibers. These fibers are also capablemore » of transmitting light more efficiently. These advantages can lead to a factor of 2-4 improvement in sensitivity and detection limit.« less

Photonic sensors review recent progress of fiber sensing technologies in Tianjin University

NASA Astrophysics Data System (ADS)

Liu, Tiegen; Liu, Kun; Jiang, Junfeng; Li, Enbang; Zhang, Hongxia; Jia, Dagong; Zhang, Yimo

2011-03-01

The up to date progress of fiber sensing technologies in Tianjin University are proposed in this paper. Fiber-optic temperature sensor based on the interference of selective higher-order modes in circular optical fiber is developed. Parallel demodulation for extrinsic Fabry-Perot interferometer (EFPI) and fiber Bragg grating (FBG) sensors is realized based on white light interference. Gas concentration detection is realized based on intra-cavity fiber laser spectroscopy. Polarization maintaining fiber (PMF) is used for distributed position or displacement sensing. Based on the before work and results, we gained National Basic Research Program of China on optical fiber sensing technology and will develop further investigation in this area.

Triaxial fiber optic magnetic field sensor for MRI applications

NASA Astrophysics Data System (ADS)

Filograno, Massimo L.; Pisco, Marco; Catalano, Angelo; Forte, Ernesto; Aiello, Marco; Soricelli, Andrea; Davino, Daniele; Visone, Ciro; Cutolo, Antonello; Cusano, Andrea

2016-05-01

In this paper, we report a fiber-optic triaxial magnetic field sensor, based on Fiber Bragg Gratings (FBGs) integrated with giant magnetostrictive material, the Terfenol-D. The realized sensor has been designed and engineered for Magnetic Resonance Imaging (MRI) applications. A full magneto-optical characterization of the triaxial sensing probe has been carried out, providing the complex relationship among the FBGs wavelength shift and the applied magnetostatic field vector. Finally, the developed fiber optic sensors have been arranged in a sensor network composed of 20 triaxial sensors for mapping the magnetic field distribution in a MRI-room at a diagnostic center in Naples (SDN), equipped with Positron emission tomography/magnetic resonance (PET/MR) instrumentation. Experimental results reveal that the proposed sensor network can be efficiently used in MRI centers for performing quality assurance tests, paving the way for novel integrated tools to measure the magnetic dose accumulated day by day by MRI operators.

Optical fiber sensors and signal processing for intelligent structure monitoring

NASA Technical Reports Server (NTRS)

Rogowski, Robert; Claus, R. O.; Lindner, D. K.; Thomas, Daniel; Cox, Dave

1988-01-01

The analytic and experimental performance of optical fiber sensors for the control of vibration of large aerospace and other structures are investigated. In particular, model domain optical fiber sensor systems, are being studied due to their apparent potential as distributed, low mass sensors of vibration over appropriate ranges of both low frequency and low amplitude displacements. Progress during the past three months is outlined. Progress since September is divided into work in the areas of experimental hardware development, analytical analysis, control design and sensor development. During the next six months, tests of a prototype closed-loop control system for a beam are planned which will demonstrate the solution of several optical fiber instrumentation device problems, the performance of the control system theory which incorporates the model of the modal domain sensor, and the potential for distributed control which this sensor approach offers.

Fiber-optic temperature sensor using a spectrum-modulating semiconductor etalon

NASA Technical Reports Server (NTRS)

Beheim, Glenn; Anthan, Donald J.; Beheim, Glenn; Anthan, Donald J.

1987-01-01

Described is a fiber-optic temperature sensor that uses a spectrum modulating SiC etalon. The spectral output of this type of sensor may be analyzed to obtain a temperature measurement which is largely independent of the transmission properties of the sensor's fiber-optic link. A highly precise laboratory spectrometer is described in detail, and this instrument is used to study the properties of this type of sensor. Also described are a number of different spectrum analyzers that are more suitable for use in a practical thermometer.

A Novel, High-Resolution, High-Speed Fiber-Optic Temperature Sensor for Oceanographic Applications

DTIC Science & Technology

2015-05-11

attached to the endface of a cleaved single-mode fiber using UV curable glue . A novel signal processing method has also been developed for the...thick Si wafer was bonded onto the tip of a single mode optical fiber using UV -curable glue . In addition to the sensor shown in Fig. 1(b), sensor...we developed a process to introduce much thicker silicon pieces onto the optical fiber tip. UV curable glue was first attached to the endface of

Theory of fiber-optic, evanescent-wave spectroscopy and sensors

NASA Astrophysics Data System (ADS)

Messica, A.; Greenstein, A.; Katzir, A.

1996-05-01

A general theory for fiber-optic, evanescent-wave spectroscopy and sensors is presented for straight, uncladded, step-index, multimode fibers. A three-dimensional model is formulated within the framework of geometric optics. The model includes various launching conditions, input and output end-face Fresnel transmission losses, multiple Fresnel reflections, bulk absorption, and evanescent-wave absorption. An evanescent-wave sensor response is analyzed as a function of externally controlled parameters such as coupling angle, f number, fiber length, and diameter. Conclusions are drawn for several experimental apparatuses.

Fabrication of fiber-optic localized surface plasmon resonance sensor and its application to detect antibody-antigen reaction of interferon-gamma

NASA Astrophysics Data System (ADS)

Jeong, Hyeon-Ho; Erdene, Norov; Lee, Seung-Ki; Jeong, Dae-Hong; Park, Jae-Hyoung

2011-12-01

A fiber-optic localized surface plasmon (FO LSPR) sensor was fabricated by gold nanoparticles (Au NPs) immobilized on the end-face of an optical fiber. When Au NPs were formed on the end-face of an optical fiber by chemical reaction, Au NPs aggregation occurred and the Au NPs were immobilized in various forms such as monomers, dimers, trimers, etc. The component ratio of the Au NPs on the end-face of the fabricated FO LSPR sensor was slightly changed whenever the sensors were fabricated in the same condition. Including this phenomenon, the FO LSPR sensor was fabricated with high sensitivity by controlling the density of Au NPs. Also, the fabricated sensors were measured for the resonance intensity for the different optical systems and analyzed for the effect on sensitivity. Finally, for application as a biosensor, the sensor was used for detecting the antibody-antigen reaction of interferon-gamma.

Lightweight Fiber Optic Gas Sensor for Monitoring Regenerative Food Production

NASA Technical Reports Server (NTRS)

Schmidlin, Edward; Goswami, Kisholoy

1995-01-01

In this final report, Physical Optics Corporation (POC) describes its development of sensors for oxygen, carbon dioxide, and relative humidity. POC has constructed a phase fluorometer that can detect oxygen over the full concentration range from 0 percent to 100 percent. Phase-based measurements offer distinct advantages, such as immunity to source fluctuation, photobleaching, and leaching. All optics, optoelectronics, power supply, and the printed circuit board are included in a single box; the only external connections to the fluorometer are the optical fiber sensor and a power cord. The indicator-based carbon dioxide sensor is also suitable for short-term and discrete measurements over the concentration range from 0 percent to 100 percent. The optical fiber-based humidity sensor contains a porous core for direct interaction of the light beam with water vapor within fiber pores; the detection range for the humidity sensor is 10 percent to 100 percent, and response time is under five minutes. POC is currently pursuing the commercialization of these oxygen and carbon dioxide sensors for environmental applications.

A Temperature Sensor Based on a Polymer Optical Fiber Macro-Bend

PubMed Central

Moraleda, Alberto Tapetado; García, Carmen Vázquez; Zaballa, Joseba Zubia; Arrue, Jon

2013-01-01

The design and development of a plastic optical fiber (POF) macrobend temperature sensor is presented. The sensor has a linear response versus temperature at a fixed bend radius, with a sensitivity of 1.92·10−3 (°C)−1. The sensor system used a dummy fiber-optic sensor for reference purposes having a resolution below 0.3 °C. A comprehensive experimental analysis was carried out to provide insight into the effect of different surrounding media on practical macro-bend POF sensor implementation. Experimental results are successfully compared with bend loss calculations. PMID:24077323

Fiber optic, Fabry-Perot high temperature sensor

NASA Technical Reports Server (NTRS)

James, K.; Quick, B.

1984-01-01

A digital, fiber optic temperature sensor using a variable Fabry-Perot cavity as the sensor element was analyzed, designed, fabricated, and tested. The fiber transmitted cavity reflection spectra is dispersed then converted from an optical signal to electrical information by a charged coupled device (CCD). A microprocessor-based color demodulation system converts the wavelength information to temperature. This general sensor concept not only utilizes an all-optical means of parameter sensing and transmitting, but also exploits microprocessor technology for automated control, calibration, and enhanced performance. The complete temperature sensor system was evaluated in the laboratory. Results show that the Fabry-Perot temperature sensor has good resolution (0.5% of full seale), high accuracy, and potential high temperature ( 1000 C) applications.

Modeling and testing of fast response, fiber-optic temperature sensors

NASA Astrophysics Data System (ADS)

Tonks, Michael James

The objective of this work was to design, analyze and test a fast response fiber-optic temperature probe and sensor. The sensor is intended for measuring rapid temperature changes such as produced by a blast wave formed by a detonation. This work was performed in coordination with Luna Innovations Incorporated, and the design is based on extensions of an existing fiber-optic temperature sensor developed by Luna. The sensor consists of a glass fiber with an optical wafer attached to the tip. A basic description of the principles behind the fiber-optic temperature sensor and an accompanying demodulation system is provided. For experimental validation tests, shock tubes were used to simulate the blast wave experienced at a distance of 3.0 m from the detonation of 22.7 kg of TNT. The flow conditions were predicted using idealized shock tube theory. The temperature sensors were tested in three configurations, flush at the end of the shock tube, extended on a probe 2.54 cm into the flow and extended on a probe 12.7 cm into the flow. The total temperature was expected to change from 300 K to 1130 K for the flush wall experiments and from 300 K to 960 K for the probe experiments. During the initial 0.1 milliseconds of the data the temperature only changed 8 K when the sensors were flush in the end of the shock tube. The sensor temperature changed 36 K during the same time when mounted on a probe in the flow. Schlieren pictures were taken of the flow in the shock tube to further understand the shock tube environment. Contrary to ideal shock tube theory, it was discovered that the flow did not remain stagnant in the end of the shock tube after the shock reflects from the end of the shock tube. Instead, the effects of turbulence were recorded with the fiber-optic sensors, and this turbulence was also captured in the schlieren photographs. A fast-response thermocouple was used to collect data for comparison with the fiber-optic sensor, and the fiber-optic sensor was proven to have a faster response time compared to the thermocouple. When the sensors were extended 12.7 cm into the flow, the fiber-optic sensors recorded a temperature change of 143 K compared to 38 K recorded by the thermocouple during the 0.5 millisecond test. This corresponds to 22% of the change of total temperature in the air recorded by the fiber-optic sensor and only 6% recorded by the thermocouple. Put another way, the fiber-optic sensor experience a rate of temperature change equal to 2.9x105 K/s and the thermocouple changed at a rate of 0.79x105 K/s. The data recorded from the fiber-optic sensor also contained much less noise than the thermocouple data. An unsteady finite element thermal model was created using ANSYS to predict the temperature response of the sensor. Test cases with known analytical solutions were used to verify the ANSYS modeling procedures. The shock tube flow environment was also modeled with Fluent, a commercially available CFD code. Fluent was used to determine the heat transfer between the shock tube flow and the sensor. The convection film coefficient for the flow was predicted by Fluent to be 27,150 W/m2K for the front of the wafer and 13,385 W/m2K for the side. The Fluent results were used with the ANSYS model to predict the response of the fiber-optic sensor when exposed to the shock tube flow. The results from the Fluent/ANSYS model were compared to the fiber-optic measurements taken in the shock tube. It was seen that the heat flux to the sensor was slightly over-predicted by the model, and the heat losses from the wafer were also over-predicted. Since the prediction fell within the uncertainty of the measurement, it was found to be in good agreement with the measured values. (Abstract shortened by UMI.)

Investigation of Carbon-Polymer Structures with Embedded Fiber-Optic Bragg Gratings

NASA Technical Reports Server (NTRS)

Grant, Joseph; Kaul, R.; Taylor, S.; Myers, G.; Sharma, A.

2003-01-01

Several Bragg-grating sensors fabricated within the same optical fiber are buried within multiple-ply carbon-epoxy planar and cylindrical structures. Effect of different orientation of fiber-sensors with respect to carbon fibers in the composite structure is investigated. This is done for both fabric and uni-tape material samples. Response of planar structures to axial and transverse strain up to 1 millistrain is investigated with distributed Bragg-grating sensors. Material properties like Young's Modulus and Poisson ratio is measured. A comparison is made between response measured by sensors in different ply-layers and those bonded on the surface. The results from buried fiber- sensors do not completely agree with surface bonded conventional strain gauges. A plausible explanation is given for observed differences. The planar structures are subjected to impacts with energies up to 10 ft-lb. Effect of this impact on the material stiffness is also investigated with buried fiber-optic Bragg sensors. The strain response of such optical sensors is also measured for cylindrical carbon-epoxy composite structures. The sensors are buried within the walls of the cylinder as well as surface bonded in both the axial as well as hoop directions. The response of these fiber-optic sensors is investigated by pressurizing the cylinder up to its burst pressure of around 1500 psi. This is done at both room temperature as well as cryogenic temperatures. The recorded response is compared with that from a conventional strain gauge.

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

PubMed

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

2014-09-22

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.

Microshell-tipped optical fibers as sensors of high-pressure pulses in adverse environments

DOE Office of Scientific and Technical Information (OSTI.GOV)

Benjamin, R.F.; Mayer, F.J.; Maynard, R.L.

1984-01-01

An optical-fiber sensor for detecting the arrival of strong pressure pulses was developed. The sensor consists of an optical fiber, tipped with a gas-filled microballoon. They have been used successfully in adverse environments including explosives, ballistics and electromagnetic pulses (EMP). The sensor produces a bright optical pulse caused by the rapid shock-heating of a gas, typically argon or xenon, which is confined in the spherical glass or plastic microballoon. The light pulse is transmitted via the optical fiber to a photo detector, usually a streak camera or photomultiplier tube. The microballoon optical sensor (called an optical pin by analogy tomore » standard electrical pins), was originally developed for diagnosing an explosive, pulsed-power generator. Optical pins are required due to the EMP. The optical pins are economical arrival-time indicators because many channels can be recorded by one streak camera. The generator tests and related experiments, involving projectile velocities and detonation velocities of several kilometers per sec have demonstrated the usefulness of the sensors in explosives and ballistics applications. The technical and cost advantages of this optical pin make it potentially useful for many electromagnetic, explosive, and ballistics applications.« less

Nitrogen-Doped Diamond Film for Optical Investigation of Hemoglobin Concentration

PubMed Central

Majchrowicz, Daria; Kosowska, Monika; Struk, Przemysław; Sobaszek, Michał; Jędrzejewska-Szczerska, Małgorzata

2018-01-01

In this work we present the fabrication and characterization of a diamond film which can be utilized in the construction of optical sensors for the investigation of biological samples. We produced a nitrogen-doped diamond (NDD) film using a microwave plasma enhanced chemical vapor deposition (MWPECVD) system. The NDD film was investigated with the use of scanning electron microscopy (SEM), atomic force microscopy (AFM) and Raman spectroscopy. The NDD film was used in the construction of the fiber optic sensor. This sensor is based on the Fabry–Pérot interferometer working in a reflective mode and the NDD film is utilized as a reflective layer of this interferometer. Application of the NDD film allowed us to obtain the sensor of hemoglobin concentration with linear work characteristics with a correlation coefficient (R2) equal to 0.988. PMID:29324715

A forty-year history of fiber optic smart structures

NASA Astrophysics Data System (ADS)

Udd, Eric; Scheel, Ingrid U.

2017-04-01

In 1977 McDonnell Douglas Astronautics Company began a project on using fiber optic sensors to support the Delta Rocket program. This resulted in a series of fiber sensors to support the measurement of rotation, acoustics, vibration, strain, and temperature for a variety of applications and early work on fiber optic smart structures. The work on fiber optic smart structures transitioned in part to Blue Road Research in 1993 and continued in 2006 to the present at Columbia Gorge Research. This paper summarizes some of the efforts made by these companies to implement fiber optic smart structures over this forty year period.

Fiber-optic sensors for aerospace electrical measurements - An update

NASA Technical Reports Server (NTRS)

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

1991-01-01

The authors report the progress made on the development of aerospace current and voltage sensors which use fiber-optic and optical sensing heads. These sensors are presently designed to cover ac frequencies from 60 Hz to 20 kHz. The current sensor, based on the Faraday effect in optical fiber, is in advanced development after some initial testing. The emphasis is on packaging methods and ways to maintain consistent sensitivity with changes in temperature. The voltage sensor, utilizing the Pockels effect in a crystal, has excelled in temperature tests. The authors report on the development of these sensors. The authors also relate the technology used in the sensors, the results of evaluation, improvements being made, and the future direction of the work.

Measuring electrically charged particle fluxes in space using a fiber optic loop sensor

NASA Technical Reports Server (NTRS)

1992-01-01

The purpose of this program was to demonstrate the potential of a fiber optic loop sensor for the measurement of electrically charged particle fluxes in space. The key elements of the sensor are a multiple turn loop of low birefringence, single mode fiber, with a laser diode light source, and a low noise optical receiver. The optical receiver is designed to be shot noise limited, with this being the limiting sensitivity factor for the sensor. The sensing element is the fiber optic loop. Under a magnetic field from an electric current flowing along the axis of the loop, there is a non-vanishing line integral along the fiber optic loop. This causes a net birefringence producing two states of polarization whose phase difference is correlated to magnetic field strength and thus, current in the optical receiver electronic processing. The objectives in this program were to develop a prototype laser diode powered fiber optic sensor. The performance specification of a minimum detectable current density of 1 (mu)amp/sq m-(radical)Hz, should be at the shot noise limit of the detection electronics. OPTRA has successfully built and tested a 3.2 m diameter loop with 137 turns of low birefringence optical fiber and achieved a minimum detectable current density of 5.4 x 10(exp-5) amps/(radical)Hz. If laboratory space considerations were not an issue, with the length of optical fiber available to us, we would have achieved a minimum detectable current density of 4 x 10(exp -7) amps/(radical)Hz.

Micromachined fiber optic Fabry-Perot underwater acoustic probe

NASA Astrophysics Data System (ADS)

Wang, Fuyin; Shao, Zhengzheng; Hu, Zhengliang; Luo, Hong; Xie, Jiehui; Hu, Yongming

2014-08-01

One of the most important branches in the development trend of the traditional fiber optic physical sensor is the miniaturization of sensor structure. Miniature fiber optic sensor can realize point measurement, and then to develop sensor networks to achieve quasi-distributed or distributed sensing as well as line measurement to area monitoring, which will greatly extend the application area of fiber optic sensors. The development of MEMS technology brings a light path to address the problems brought by the procedure of sensor miniaturization. Sensors manufactured by MEMS technology possess the advantages of small volume, light weight, easy fabricated and low cost. In this paper, a fiber optic extrinsic Fabry-Perot interferometric underwater acoustic probe utilizing micromachined diaphragm collaborated with fiber optic technology and MEMS technology has been designed and implemented to actualize underwater acoustic sensing. Diaphragm with central embossment, where the embossment is used to anti-hydrostatic pressure which would largely deflect the diaphragm that induce interferometric fringe fading, has been made by double-sided etching of silicon on insulator. By bonding the acoustic-sensitive diaphragm as well as a cleaved fiber end in ferrule with an outer sleeve, an extrinsic Fabry-Perot interferometer has been constructed. The sensor has been interrogated by quadrature-point control method and tested in field-stable acoustic standing wave tube. Results have been shown that the recovered signal detected by the sensor coincided well with the corresponding transmitted signal and the sensitivity response was flat in frequency range from 10 Hz to 2kHz with the value about -154.6 dB re. 1/μPa. It has been manifest that the designed sensor could be used as an underwater acoustic probe.

Development and Performance Evaluation of Optical Sensors for High Temperature Engine Applications

NASA Technical Reports Server (NTRS)

Adamovsky, G.; Varga, D.; Floyd, B.

2011-01-01

This paper discusses fiber optic sensors designed and constructed to withstand extreme temperatures of aircraft engine. The paper describes development and performance evaluation of fiber optic Bragg grating based sensors. It also describes the design and presents test results of packaged sensors subjected to temperatures up to 1000 C for prolonged periods of time.

Optical Fiber Sensors For Monitoring Joint Articulation And Chest Expansion Of A Human Body

DOEpatents

Muhs, Jeffrey D.; Allison, Stephen W.

1997-12-23

Fiber-optic sensors employing optical fibers of elastomeric material are incorporated in devices adapted to be worn by human beings in joint and chest regions for the purpose of monitoring and measuring the extent of joint articulation and chest expansion especially with respect to time.

Chalcogenide fiber-optic SPR chemical sensor with MoS2 monolayer, polymer clad, and polythiophene layer in NIR using selective ray launching

NASA Astrophysics Data System (ADS)

Sharma, Anuj K.; Kaur, Baljinder

2018-07-01

Surface plasmon resonance (SPR) based chalcogenide fiber-optic sensor with polymer clad and MoS2 monolayer is simulated and analyzed in near infrared (NIR) for detection of mixture of alcohols (ethanol and methanol) dissolved in water solution. The proposed fiber optic sensor is analyzed under angular interrogation method, which is based on selective ray (on-axis) launching of monochromatic light into the fiber core at varying angle followed by measuring the loss of power (in dB) after passing through the SPR probe region. The performance of the sensor is analyzed in terms of its figure of merit (FOM). The sensor's specificity towards alcohols along with considerably larger FOM is achieved by utilizing a polythiophene (PT) layer. The results indicate that longer NIR wavelength (λ) provides superior sensing performance. The sensor's performance is better for larger volume fraction of methanol in the water solution. The proposed fiber optic SPR sensor has the capability of providing much greater FOM compared with the previously-reported SPR sensors.

Distributed fluorescent optical fiber proximity sensor: Towards a proof of concept.

PubMed

Gălătuș, Ramona; Faragó, Paul; Miluski, Piotr; Valles, Juan-Antonio

2018-06-05

Fluorescent fibers are optical fibers which emit light as a response to an incident phenomenon, usually an incident light. Operation depends on the doping dyes, which determine specific fluorescence and optical characteristics useful in the development of optical sensors. In this work we propose a low-cost distributed proximity sensor implemented using a red fluorescent fiber, to provide a security option for a surface plasmon resonance system. Operation of the proposed sensor relies on having the incident illumination intensity varied by the presence or absence of an obstacle in the vicinity of the sensing element. This will influence the radiated fluorescence accordingly. The proposed setup for the implementation of the optical proximity sensor assumes having a high brightness LED deployed for axial fiber illumination and a blue LED for side illumination. Electronic processing then accounts for gain and digitization. Measurement results of the prototype validate the proposed concept. Copyright © 2018 Elsevier B.V. All rights reserved.

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

NASA Astrophysics Data System (ADS)

Yamazaki, Hiroshi; Koyama, Yuya; Watanabe, Kazuhiro

2014-05-01

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

Optical feedback-induced light modulation for fiber-based laser ablation.

PubMed

Kang, Hyun Wook

2014-11-01

Optical fibers have been used as a minimally invasive tool in various medical fields. However, due to excessive heat accumulation, the distal end of a fiber often suffers from severe melting or devitrification, leading to the eventual fiber failure during laser treatment. In order to minimize thermal damage at the fiber tip, an optical feedback sensor was developed and tested ex vivo. Porcine kidney tissue was used to evaluate the feasibility of optical feedback in terms of signal activation, ablation performance, and light transmission. Testing various signal thresholds demonstrated that 3 V was relatively appropriate to trigger the feedback sensor and to prevent the fiber deterioration during kidney tissue ablation. Based upon the development of temporal signal signatures, full contact mode rapidly activated the optical feedback sensor possibly due to heat accumulation. Modulated light delivery induced by optical feedback diminished ablation efficiency by 30% in comparison with no feedback case. However, long-term transmission results validated that laser ablation assisted with optical feedback was able to almost consistently sustain light delivery to the tissue as well as ablation efficiency. Therefore, an optical feedback sensor can be a feasible tool to protect optical fiber tips by minimizing debris contamination and delaying thermal damage process and to ensure more efficient and safer laser-induced tissue ablation.

Optical fiber sensors for damage analysis in aerospace materials

NASA Technical Reports Server (NTRS)

Schindler, Paul; May, Russell; Claus, Richard

1995-01-01

Under this grant, fiber optic sensors were investigated for use in the nondestructive evaluation of aging aircraft. Specifically, optical fiber sensors for detection and location of impacts on a surface, and for detection of corrosion in metals were developed. The use of neural networks was investigated for determining impact location by processing the output of a network of fiberoptic strain sensors distributed on a surface. This approach employs triangulation to determine location by comparing the arrival times at several sensors, of the acoustic signal generated by the impact. For this study, a neural network simulator running on a personal computer was used to train a network using a back-propagation algorithm. Fiber optic extrinsic Fabry-Perot interferometer (EFPI) strain sensors are attached to or embedded in the surface, so that stress waves emanating from an impact can be detected. The ability of the network to determine impact location by time-or-arrival of acoustic signals was assessed by comparing network outputs with actual experimental results using impacts on a panel instrumented with optical fiber sensors. Using the neural network to process the sensor outputs, the impact location can be inferred to centimeter range accuracy directly from the arrival time data. In addition, the network can be trained to determine impact location, regardless of material anisotropy. Results demonstrate that a back-propagation network identifies impact location for an anisotropic graphite/bismaleimide plate with the same accuracy as that for an isotropic aluminum plate. Two different approaches were investigated for the development of fiber optic sensors for corrosion detection in metals, both utilizing optical fiber sensors with metal coatings. In the first approach, an extrinsic Fabry-Perot interferometric fiber optic strain sensor was placed under tensile stress, and while in the resulting strained position, a thick coating of metal was applied. Due to an increase in the quantity of material, the sensor does not return to its original position upon removal of the applied stress, and some residual strain is maintained within the sensor element. As the metal thickness decreases due to corrosion, this strain is released, providing the sensing mechanism for corrosion detection. In the second approach, photosensitive optical fibers with long period Bragg gratings in the core were coated with metal. The Bragg gratings serve to couple core modes at discrete wavelengths to cladding modes. Since cladding modes interact with the metal coating surrounding the fiber cladding, the specific wavelengths coupled from core to cladding depend on the refractive index of the metal coating. Therefore, as the metal corrodes, the resulting change in index of the coating may be measured by measuring the change in wavelength of the coupled mode. Results demonstrate that both approaches can be successfully used to track the loss in metal coating on the optical fiber sensors due to corrosion.

Microbend fiber-optic chemical sensor

DOEpatents

Weiss, Jonathan D.

2002-01-01

A microbend fiber-optic chemical sensor for detecting chemicals in a sample, and a method for its use, is disclosed. The sensor comprises at least one optical fiber having a microbend section (a section of small undulations in its axis), for transmitting and receiving light. In transmission, light guided through the microbend section scatters out of the fiber core and interacts, either directly or indirectly, with the chemical in the sample, inducing fluorescence radiation. Fluorescence radiation is scattered back into the microbend section and returned to an optical detector for determining characteristics of the fluorescence radiation quantifying the presence of a specific chemical.

Dynamic Strain Measured by Mach-Zehnder Interferometric Optical Fiber Sensors

PubMed Central

Her, Shiuh-Chuan; Yang, Chih-Min

2012-01-01

Optical fibers possess many advantages such as small size, light weight and immunity to electro-magnetic interference that meet the sensing requirements to a large extent. In this investigation, a Mach-Zehnder interferometric optical fiber sensor is used to measure the dynamic strain of a vibrating cantilever beam. A 3 × 3 coupler is employed to demodulate the phase shift of the Mach-Zehnder interferometer. The dynamic strain of a cantilever beam subjected to base excitation is determined by the optical fiber sensor. The experimental results are validated with the strain gauge. PMID:22737010

Sensitivity optimization of ZnO clad-modified optical fiber humidity sensor by means of tuning the optical fiber waist diameter

NASA Astrophysics Data System (ADS)

Azad, Saeed; Sadeghi, Ebrahim; Parvizi, Roghaieh; Mazaheri, Azardokht; Yousefi, M.

2017-05-01

In this work, the multimode optical fiber size effects on the performances of the clad-modified fiber with ZnO nanorods relative humidity (RH) sensor were experimentally investigated. Simple and controlled chemical etching method through on line monitoring was used to prepare different fiber waist diameter with long length of 15 mm. More precisely, the competition behavior of sensor performances with varying fiber waist diameter was studied to find appropriate size of maximizing evanescent fields. The obtained results revealed that evanescent wave absorption coefficient (γ) enhanced more than 10 times compare to bare fiber at the proposed optimum fiber diameter of 28 μm. Also, high linearity and fast recovery time about 7 s was obtained at the proposed fiber waist diameter. Applicable features of the proposed sensor allow this device to be used for humidity sensing applications, especially to be applied in remote sensing technologies.

Time-domain fiber loop ringdown sensor and sensor network

NASA Astrophysics Data System (ADS)

Kaya, Malik

Optical fibers have been mostly used in fiber optic communications, imaging optics, sensing technology, etc. Fiber optic sensors have gained increasing attention for scientific and structural health monitoring (SHM) applications. In this study, fiber loop ringdown (FLRD) sensors were fabricated for scientific, SHM, and sensor networking applications. FLRD biosensors were fabricated for both bulk refractive index (RI)- and surface RI-based DNA sensing and one type of bacteria sensing. Furthermore, the effect of glucose oxidase (GOD) immobilization at the sensor head on sensor performance was evaluated for both glucose and synthetic urine solutions with glucose concentration between 0.1% and 10%. Detection sensitivities of the glucose sensors were achieved as low as 0.05%. For chemical sensing, heavy water, ranging from 97% to 10%, and several elemental solutions were monitored by using the FLRD chemical sensors. Bulk index-based FLRD sensing showed that trace elements can be detected in deionized water. For physical sensing, water and cracking sensors were fabricated and embedded into concrete. A partially-etched single-mode fiber (SMF) was embedded into a concrete bar for water monitoring while a bare SMF without any treatment was directly embedded into another concrete bar for monitoring cracks. Furthermore, detection sensitivities of water and crack sensors were investigated as 10 ml water and 0.5 mm surface crack width, respectively. Additionally fiber loop ringdown-fiber Bragg grating temperature sensors were developed in the laboratory; two sensor units for water, crack, and temperature sensing were deployed into a concrete cube in a US Department of Energy test bed (Miami, FL). Multi-sensor applications in a real concrete structure were accomplished by testing the six FLRD sensors. As a final stage, a sensor network was assembled by multiplexing two or three FLRD sensors in series and parallel. Additionally, two FLRD sensors were combined in series and parallel by using a 2x1 micro-electromechanical system optical switch to control sensors individually. For both configurations, contributions of each sensor to two or three coupled signals were simulated theoretically. Results show that numerous FLRD sensors can be connected in different configurations, and a sensor network can be built up for multi-function sensing applications.

Novel Modified Optical Fibers for High Temperature In-Situ Miniaturized Gas Sensors in Advanced Fossil Energy Systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pickrell, Gary; Scott, Brian

2014-06-30

This report covers the technical progress on the program “Novel Modified Optical Fibers for High Temperature In-Situ Miniaturized Gas Sensors in Advanced Fossil Energy Systems”, funded by the National Energy Technology Laboratory of the U.S. Department of Energy, and performed by the Materials Science & Engineering and Electrical & Computer Engineering Departments at Virginia Tech, and summarizes technical progress from July 1st, 2005 –June 30th, 2014. The objective of this program was to develop novel fiber materials for high temperature gas sensors based on evanescent wave absorption in optical fibers. This project focused on two primary areas: the study ofmore » a sapphire photonic crystal fiber (SPCF) for operation at high temperature and long wavelengths, and a porous glass based fiber optic sensor for gas detection. The sapphire component of the project focused on the development of a sapphire photonic crystal fiber, modeling of the new structures, fabrication of the optimal structure, development of a long wavelength interrogation system, testing of the optical properties, and gas and temperature testing of the final sensor. The fabrication of the 6 rod SPCF gap bundle (diameter of 70μm) with a hollow core was successfully constructed with lead-in and lead-out 50μm diameter fiber along with transmission and gas detection testing. Testing of the sapphire photonic crystal fiber sensor capabilities with the developed long wavelength optical system showed the ability to detect CO 2 at or below 1000ppm at temperatures up to 1000°C. Work on the porous glass sensor focused on the development of a porous clad solid core optical fiber, a hollow core waveguide, gas detection capabilities at room and high temperature, simultaneous gas species detection, suitable joining technologies for the lead-in and lead-out fibers and the porous sensor, sensor system sensitivity improvement, signal processing improvement, relationship between pore structure and fiber geometry to optical properties, and the development of a sensor packaging prototype for laboratory testing. Analysis and experiments determined that a bonding technique using a CO 2 laser is the most suitable joining technique. Pore morphology alteration showed that transmission improved with increasing annealing temperature (producing smaller pores), while the sensor response time increased and the mechanical strength decreased with increasing annealing temperature. Software was developed for data acquisition and signal processing to collect and interpret spectral gas absorption data. Gas detection on porous glass sensors was completed and the detection limit was evaluated using acetylene and was found to be around 1- 200ppm. A complete materials package for porous glass sensors was manufactured for testing.« less

The role of local interaction mechanics in fiber optic smart structures

NASA Astrophysics Data System (ADS)

Sirkis, J. S.; Dasgupta, A.

1993-04-01

The concept of using 'smart' composite materials/structures with built-in self-diagnostic capabilities for health monitoring involves embedding discrete and/or distributed sensory networks in the host composite material, along with a central and/or distributed artificial intelligence capability for signal processing, data collection, interpretation and diagnostic evaluations. This article concentrates on the sensory functions in 'smart' structure applications and concentrates in particular on optical fiber sensors. Specifically, we present an overview of recent research dealing with the basic mechanics of local interactions between the embedded optical fiber sensors and the surrounding host composite. The term 'local' is defined by length scales on the order of several optical fiber diameters. We examine some generic issues, such as the 'calibration' and 'obtrusivity' of the sensor, and the inherent damage caused by the sensor inclusions to the surrounding host and vice-versa under internal and/or external applied loads. Analytical, numerical and experimental results are presented regarding the influence of local strain concentrations caused by the sensory inclusions on sensor and host performance. The important issues examined are the local mechanistic effects of optical fiber coatings on the behavior of the sensor and the host, and mechanical survivability of optical fibers experiencing quasi-static and time-varying thermomechanical loading.

Pressure Measurement Sensor

NASA Technical Reports Server (NTRS)

1997-01-01

FFPI Industries Inc. is the manufacturer of fiber-optic sensors that furnish accurate pressure measurements in internal combustion chambers. Such an assessment can help reduce pollution emitted by these engines. A chief component in the sensor owes its seven year- long development to Lewis Research Center funding to embed optical fibers and sensors in metal parts. NASA support to Texas A&M University played a critical role in developing this fiber optic technology and led to the formation of FFPI Industries and the production of fiber sensor products. The simple, rugged design of the sensor offers the potential for mass production at low cost. Widespread application of the new technology is forseen, from natural gas transmission, oil refining and electrical power generation to rail transport and the petrochemical paper product industry.

Power inverter with optical isolation

DOEpatents

Duncan, Paul G.; Schroeder, John Alan

2005-12-06

An optically isolated power electronic power conversion circuit that includes an input electrical power source, a heat pipe, a power electronic switch or plurality of interconnected power electronic switches, a mechanism for connecting the switch to the input power source, a mechanism for connecting comprising an interconnecting cable and/or bus bar or plurality of interconnecting cables and/or input bus bars, an optically isolated drive circuit connected to the switch, a heat sink assembly upon which the power electronic switch or switches is mounted, an output load, a mechanism for connecting the switch to the output load, the mechanism for connecting including an interconnecting cable and/or bus bar or plurality of interconnecting cables and/or output bus bars, at least one a fiber optic temperature sensor mounted on the heat sink assembly, at least one fiber optic current sensor mounted on the load interconnection cable and/or output bus bar, at least one fiber optic voltage sensor mounted on the load interconnection cable and/or output bus bar, at least one fiber optic current sensor mounted on the input power interconnection cable and/or input bus bar, and at least one fiber optic voltage sensor mounted on the input power interconnection cable and/or input bus bar.

Sensored fiber reinforced polymer grate

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ross, Michael P.; Mack, Thomas Kimball

Various technologies described herein pertain to a sensored grate that can be utilized for various security fencing applications. The sensored grate includes a grate framework and an embedded optical fiber. The grate framework is formed of a molded polymer such as, for instance, molded fiber reinforced polymer. Further, the grate framework includes a set of elongated elements, where the elongated elements are spaced to define apertures through the grate framework. The optical fiber is embedded in the elongated elements of the grate framework. Moreover, bending or breaking of one or more of the elongated elements can be detected based onmore » a change in a characteristic of input light provided to the optical fiber compared to output light received from the optical fiber.« less

Improved vibration sensor based on a biconical tapered singlemode fiber, using in-fiber Mach-Zehnder interferometer

NASA Astrophysics Data System (ADS)

Wonko, R.; Moś, J. E.; Stasiewicz, K. A.; Jaroszewicz, L. R.

2017-05-01

Optical fiber vibration sensors are an appropriate alternative for piezoelectric devices, which are electromagnetic sensitive to the external conditions. Most of the vibration sensors demonstrated in previous publications resist to different interferometers or Bragg's gratings. Such sensors require a long time of stabilization of an optical signal, because they are vulnerable to undesirable disturbance. In majority, time response of an optical sensor should be instantaneous, therefore we have proposed an in- line vibration sensing passive element based on a tapered fiber. Micrometer sized optical fiber tapers are attractive for many optical areas due to changes process of boundary conditions. Such phenomena allow for a sensitive detection of the modulation phase. Our experiment shows that a singlemode, adiabatic tapered fiber enables detecting an acoustic vibration. In this study, we report on Mach- Zehnder (MZ) interferometer as a vibration sensor which was composed of two 50/50 couplers at 1550 nm. In the reference arm we used a 4 meter singlemode optical fiber (SMF28), while in the arm under test we placed tapered optical fibers attached to a metal plate, put directly on speaker. Researches carried out on different tapered fibers which diameter of a taper waist was in the range from 5 μm to 25 μm, and each taper was characterized by optical losses less than 0,5 dB. The measured phase changes were over a frequency from 100 Hz to 1 kHz and an amplitude in the range from 100 mVpp to 1 Vpp. Although on account of a limited space we have showed only the results for 100 Hz. Nevertheless, experimental results show that this sensing system has a wide frequency response range from a few hertz to one of kilohertz, however for some conditions, a standard optical fiber showed better result.

Optical fiber sensors for harsh environments

DOEpatents

Xu, Juncheng; Wang, Anbo

2007-02-06

A diaphragm optic sensor comprises a ferrule including a bore having an optical fiber disposed therein and a diaphragm attached to the ferrule, the diaphragm being spaced apart from the ferrule to form a Fabry-Perot cavity. The cavity is formed by creating a pit in the ferrule or in the diaphragm. The components of the sensor are preferably welded together, preferably by laser welding. In some embodiments, the entire ferrule is bonded to the fiber along the entire length of the fiber within the ferrule; in other embodiments, only a portion of the ferrule is welded to the fiber. A partial vacuum is preferably formed in the pit. A small piece of optical fiber with a coefficient of thermal expansion chosen to compensate for mismatches between the main fiber and ferrule may be spliced to the end of the fiber.

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

NASA Astrophysics Data System (ADS)

Black, Richard J.; Moslehi, Behzad

2010-09-01

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.

Liquid droplet sensing using twisted optical fiber couplers fabricated by hydrofluoric acid flow etching

NASA Astrophysics Data System (ADS)

Son, Gyeongho; Jung, Youngho; Yu, Kyoungsik

2017-04-01

We report a directional-coupler-based refractive index sensor and its cost-effective fabrication method using hydrofluoric acid droplet wet-etching and surface-tension-driven liquid flows. The proposed fiber sensor consists of a pair of twisted tapered optical fibers with low excess losses. The fiber cores in the etched microfiber region are exposed to the surrounding medium for efficient interaction with the guided light. We observe that the etching-based low-loss fiber-optic sensors can measure the water droplet volume by detecting the refractive index changes of the surrounding medium around the etched fiber core region.

Multimode-singlemode-multimode optical fiber sensor coated with novolac resin for detecting liquid phase alcohol

NASA Astrophysics Data System (ADS)

Marfu'ah, Amalia, Niza Rosyda; Hatta, Agus Muhamad; Pratama, Detak Yan

2018-04-01

Alcohol sensor based on multimode-singlemode-multimode (MSM) optical fiber with novolac resin as the external medium is proposed and demonstrated experimentally. Novolac resin swells when it is exposed by the alcohol. This effect causes a change in the polymer density leading to the refractive index's variation. The transmission light of the sensor depends on the refractive index of external medium. Based on the results, alcohol sensor based on MSM optical fiber structure using novolac resin has a higher sensitivity compared to the sensor without using novolac resin in the mixture of alcohol and distilled water. Alcohol sensor based on MSM optical fiber structure using novolac resin in the mixture of alcohol and distilled water with a singlemode fiber length of 5 mm has a sensitivity of 0.028972 dBm per % V/V, and in the mixture of alcohol and sugar solution of 10% w/w has a sensitivity of 0.005005 dBm per % V/V.

Surface plasmon resonance based fiber optic detection of chlorine utilizing polyvinylpyrolidone supported zinc oxide thin films.

PubMed

Tabassum, Rana; Gupta, Banshi D

2015-03-21

A highly sensitive chlorine sensor for an aqueous medium is fabricated using an optical fiber surface plasmon resonance (OFSPR) system. An OFSPR-based chlorine sensor is designed with a multilayer-type platform by zinc oxide (ZnO) and polyvinylpyrollidone (PVP) film morphology manipulations. Among all the methodologies of transduction reported in the field of solid state chemical and biochemical sensing, our attention is focused on the Kretschmann configuration optical fiber sensing technique using the mechanism of surface plasmon resonance. The optical fiber surface plasmon resonance (SPR) chlorine sensor is developed using a multimode optical fiber with the PVP-supported ZnO film deposited over a silver-coated unclad core of the fiber. A spectral interrogation mode of operation is used to characterize the sensor. In an Ag/ZnO/PVP multilayer system, the absorption of chlorine in the vicinity of the sensing region is performed by the PVP layer and the zinc oxide layer enhances the shift in resonance wavelength. It is, experimentally, demonstrated that the SPR wavelength shifts nonlinearly towards the red side of the visible region with an increase in the chlorine concentration in an aqueous medium while the sensitivity of the sensor decreases linearly with an increase in the chlorine concentration. As the proposed sensor utilizes an optical fiber, it possesses the additional advantages of fiber such as less signal degradation, less susceptibility to electromagnetic interference, possibility of remote sensing, probe miniaturization, probe re-usability, online monitoring, small size, light weight and low cost.

Fiber optic sensor based on Mach-Zehnder interferometer for securing entrance areas of buildings

NASA Astrophysics Data System (ADS)

Nedoma, Jan; Fajkus, Marcel; Martinek, Radek; Mec, Pavel; Novak, Martin; Bednarek, Lukas; Vasinek, Vladimir

2017-10-01

Authors of this article focused on the utilization of fiber optic sensors based on interferometric measurements for securing entrance areas of buildings such as windows and doors. We described the implementation of the fiber-optic interferometer (type Mach-Zehnder) into the window frame or door, sensor sensitivity, analysis of the background noise and methods of signal evaluation. The advantage of presented solution is the use of standard telecommunication fiber standard G.652.D, high sensitivity, immunity of sensor to electromagnetic interference (EMI) and passivity of the sensor regarding power supply. Authors implemented the Graphical User Interface (GUI) which offers the possibility of remote monitoring presented sensing solution.

Fiber optic sensor for monitoring a density of road traffic

NASA Astrophysics Data System (ADS)

Nedoma, Jan; Fajkus, Marcel; Martinek, Radek; Mec, Pavel; Novak, Martin; Jargus, Jan; Vasinek, Vladimir

2017-10-01

Authors of this article have focused on the use of fiber-optic technology in the car traffic. The article describes the use of fiber-optic interferometer for the purpose of the dynamic calculation of traffic density and inclusion the vehicle into the traffic lane. The objective is to increase safety and traffic flow. Presented solution is characterized by the non-destructive character to the road - sensor no need built into the roadway. The sensor works with standard telecommunications fibers of the G.652 standard. Other hallmarks are immunity to electromagnetic interference (EMI) and passivity of concerning the power supply. The massive expansion of optical cables within telecommunication needs along roads offers the possibility of connecting to the existing telecommunications fiber-optic network without a converter. Information can be transmitted at distances of several km up to tens km by this fiber-optic network. Set of experimental measurements in real traffic flow verified the functionality of presented solution.

A novel optical fiber displacement sensor of wider measurement range based on neural network

NASA Astrophysics Data System (ADS)

Guo, Yuan; Dai, Xue Feng; Wang, Yu Tian

2006-02-01

By studying on the output characteristics of random type optical fiber sensor and semicircular type optical fiber sensor, the ratio of the two output signals was used as the output signal of the whole system. Then the measurement range was enlarged, the linearity was improved, and the errors of reflective and absorbent changing of target surface are automatically compensated. Meantime, an optical fiber sensor model of correcting static error based on BP artificial neural network(ANN) is set up. So the intrinsic errors such as effects of fluctuations in the light, circuit excursion, the intensity losses in the fiber lines and the additional losses in the receiving fiber caused by bends are eliminated. By discussing in theory and experiment, the error of nonlinear is 2.9%, the measuring range reaches to 5-6mm and the relative accuracy is 2%.And this sensor has such characteristics as no electromagnetic interference, simple construction, high sensitivity, good accuracy and stability. Also the multi-point sensor system can be used to on-line and non-touch monitor in working locales.

Detection of Ultrasonic Stress Waves in Structures Using 3D Shaped Optic Fiber Based on a Mach-Zehnder Interferometer.

PubMed

Lan, Chengming; Zhou, Wensong; Xie, Yawen

2018-04-16

This work proposes a 3D shaped optic fiber sensor for ultrasonic stress waves detection based on the principle of a Mach–Zehnder interferometer. This sensor can be used to receive acoustic emission signals in the passive damage detection methods and other types of ultrasonic signals propagating in the active damage detection methods, such as guided wave-based methods. The sensitivity of an ultrasonic fiber sensor based on the Mach–Zehnder interferometer mainly depends on the length of the sensing optical fiber; therefore, the proposed sensor achieves the maximum possible sensitivity by wrapping an optical fiber on a hollow cylinder with a base. The deformation of the optical fiber is produced by the displacement field of guided waves in the hollow cylinder. The sensor was first analyzed using the finite element method, which demonstrated its basic sensing capacity, and the simulation signals have the same characteristics in the frequency domain as the excitation signal. Subsequently, the primary investigations were conducted via a series of experiments. The sensor was used to detect guided wave signals excited by a piezoelectric wafer in an aluminum plate, and subsequently it was tested on a reinforced concrete beam, which produced acoustic emission signals via impact loading and crack extension when it was loaded to failure. The signals obtained from a piezoelectric acoustic emission sensor were used for comparison, and the results indicated that the proposed 3D fiber optic sensor can detect ultrasonic signals in the specific frequency response range.

Detection of Ultrasonic Stress Waves in Structures Using 3D Shaped Optic Fiber Based on a Mach–Zehnder Interferometer

PubMed Central

Xie, Yawen

2018-01-01

This work proposes a 3D shaped optic fiber sensor for ultrasonic stress waves detection based on the principle of a Mach–Zehnder interferometer. This sensor can be used to receive acoustic emission signals in the passive damage detection methods and other types of ultrasonic signals propagating in the active damage detection methods, such as guided wave-based methods. The sensitivity of an ultrasonic fiber sensor based on the Mach–Zehnder interferometer mainly depends on the length of the sensing optical fiber; therefore, the proposed sensor achieves the maximum possible sensitivity by wrapping an optical fiber on a hollow cylinder with a base. The deformation of the optical fiber is produced by the displacement field of guided waves in the hollow cylinder. The sensor was first analyzed using the finite element method, which demonstrated its basic sensing capacity, and the simulation signals have the same characteristics in the frequency domain as the excitation signal. Subsequently, the primary investigations were conducted via a series of experiments. The sensor was used to detect guided wave signals excited by a piezoelectric wafer in an aluminum plate, and subsequently it was tested on a reinforced concrete beam, which produced acoustic emission signals via impact loading and crack extension when it was loaded to failure. The signals obtained from a piezoelectric acoustic emission sensor were used for comparison, and the results indicated that the proposed 3D fiber optic sensor can detect ultrasonic signals in the specific frequency response range. PMID:29659540

A fiber optic temperature sensor based on multi-core microstructured fiber with coupled cores for a high temperature environment

NASA Astrophysics Data System (ADS)

Makowska, A.; Markiewicz, K.; Szostkiewicz, L.; Kolakowska, A.; Fidelus, J.; Stanczyk, T.; Wysokinski, K.; Budnicki, D.; Ostrowski, L.; Szymanski, M.; Makara, M.; Poturaj, K.; Tenderenda, T.; Mergo, P.; Nasilowski, T.

2018-02-01

Sensors based on fiber optics are irreplaceable wherever immunity to strong electro-magnetic fields or safe operation in explosive atmospheres is needed. Furthermore, it is often essential to be able to monitor high temperatures of over 500°C in such environments (e.g. in cooling systems or equipment monitoring in power plants). In order to meet this demand, we have designed and manufactured a fiber optic sensor with which temperatures up to 900°C can be measured. The sensor utilizes multi-core fibers which are recognized as the dedicated medium for telecommunication or shape sensing, but as we show may be also deployed advantageously in new types of fiber optic temperature sensors. The sensor presented in this paper is based on a dual-core microstructured fiber Michelson interferometer. The fiber is characterized by strongly coupled cores, hence it acts as an all-fiber coupler, but with an outer diameter significantly wider than a standard fused biconical taper coupler, which significantly increases the coupling region's mechanical reliability. Owing to the proposed interferometer imbalance, effective operation and high-sensitivity can be achieved. The presented sensor is designed to be used at high temperatures as a result of the developed low temperature chemical process of metal (copper or gold) coating. The hermetic metal coating can be applied directly to the silica cladding of the fiber or the fiber component. This operation significantly reduces the degradation of sensors due to hydrolysis in uncontrolled atmospheres and high temperatures.

Fiber waveguide sensors for intelligent materials

NASA Technical Reports Server (NTRS)

Flax, A. R.; Claus, R. O.

1988-01-01

This report, an addendum to the six month report submitted to NASA Langley Research Center in December 1987, covers research performed by the Fiber and Electro-Optics Research Center (FEORC) at Virginia Tech for the NASA Langley Research Center, Grant NAG1-780, for the period from December 1987 to June 1988. This final report discusses the research performed in the following four areas as described in the proposal: Fabrication of Sensor Fibers Optimized for Embedding in Advanced Composites; Fabrication of Sensor Fiber with In-Line Splices and Evaluation via OTR methods; Modal Domain Optical Fiber Sensor Analysis; and Acoustic Fiber Waveguide Implementation.

Improved Optical-Fiber Temperature Sensors

NASA Technical Reports Server (NTRS)

Rogowski, Robert S.; Egalon, Claudio O.

1993-01-01

In optical-fiber temperature sensors of proposed type, phosphorescence and/or fluorescence in temperature-dependent coating layers coupled to photodetectors. Phosphorescent and/or fluorescent behavior(s) of coating material(s) depend on temperature; coating material or mixture of materials selected so one can deduce temperature from known temperature dependence of phosphorescence and/or fluorescence spectrum, and/or characteristic decay of fluorescence. Basic optical configuration same as that of optical-fiber chemical detectors described in "Making Optical-Fiber Chemical Detectors More Sensitive" (LAR-14525).

Fiber-Optic Micrometeoroid/Orbital Debris Impact Detector System

NASA Technical Reports Server (NTRS)

Christiansen, Eric L.; Tennyson, R. C.; Morison, W. D.

2012-01-01

A document describes a reliable, lightweight micrometeoroid/orbital debris (MMOD) detection system that can be located at strategic positions of "high consequence" to provide real-time warning of a penetration, its location, and the extent of the damage to a spacecraft. The concept is to employ fiber-optic sensors to detect impact damage and penetration of spacecraft structures. The fibers are non-electrical, employ light waves, and are immune to electromagnetic interference. The fiber-optic sensor array can be made as a stand-alone product, being bonded to a flexible membrane material or a structure that is employed as a MMOD shield material. The optical sensors can also be woven into hybrid MMOD shielding fabrics. The glass fibers of the fiber-optic sensor provide a dual purpose in contributing to the breakup of MMOD projectiles. The grid arrays can be made in a modular configuration to provide coverage over any area desired. Each module can be connected to a central scanner instrument and be interrogated in a continuous or periodic mode.

Fiber optics for aircraft engine/inlet control

NASA Technical Reports Server (NTRS)

Baumbick, R. J.

1981-01-01

NASA programs that focus on the use of fiber optics for aircraft engine/inlet control are reviewed. Fiber optics for aircraft control is attractive because of its inherent immunity to EMI and RFI noise. Optical signals can be safely transmitted through areas that contain flammable or explosive materials. The use of optics also makes remote sensing feasible by eliminating the need for electrical wires to be connected between sensors and computers. Using low-level optical signals to control actuators is also feasible when power is generated at the actuator. Each application of fiber optics for aircraft control has different requirements for both the optical cables and the optical connectors. Sensors that measure position and speed by using slotted plates can use lossy cables and bundle connectors if data transfer is in the parallel mode. If position and speed signals are multiplexed, cable and connector requirements change. Other sensors that depend on changes in transmission through materials require dependable characteristics of both the optical cables and the optical connectors. A variety of sensor types are reviewed, including rotary position encoders, tachometers, temperature sensors, and blade tip clearance sensors for compressors and turbines. Research on a gallium arsenide photoswitch for optically switched actuators that operate at 250 C is also described.

Fiber-optic sensor applications in civil and geotechnical engineering

NASA Astrophysics Data System (ADS)

Habel, Wolfgang R.; Krebber, Katerina

2011-09-01

Different types of fiber-optic sensors based on glass or polymeric fibers are used to evaluate material behavior or to monitor the integrity and long-term stability of load-bearing structure components. Fiber-optic sensors have been established as a new and innovative measurement technology in very different fields, such as material science, civil engineering, light-weight structures, geotechnical areas as well as chemical and high-voltage substations. Very often, mechanical quantities such as deformation, strain or vibration are requested. However, measurement of chemical quantities in materials and structure components, such as pH value in steel reinforced concrete members also provides information about the integrity of concrete structures. A special fiber-optic chemical sensor for monitoring the alkaline state (pH value) of the cementitious matrix in steel-reinforced concrete structures with the purpose of early detection of corrosion-initiating factors is described. The paper presents the use of several fiber-optic sensor technologies in engineering. One example concerns the use of highly resolving concrete-embeddable fiber Fabry-Perot acoustic emission (AE) sensors for the assessment of the bearing behaviour of large concrete piles in existing foundations or during and after its installation. Another example concerns fiber Bragg grating (FBG) sensors attached to anchor steels (micro piles) to measure the strain distribution in loaded soil anchors. Polymer optical fibers (POF) can be — because of their high elasticity and high ultimate strain — well integrated into textiles to monitor their deformation behaviour. Such "intelligent" textiles are capable of monitoring displacement of soil or slopes, critical mechanical deformation in geotechnical structures (dikes, dams, and embankments) as well as in masonry structures during and after earthquakes.

Polymer optical fiber strain gauge for human-robot interaction forces assessment on an active knee orthosis

NASA Astrophysics Data System (ADS)

Leal-Junior, Arnaldo G.; Frizera, Anselmo; Marques, Carlos; Sánchez, Manuel R. A.; Botelho, Thomaz R.; Segatto, Marcelo V.; Pontes, Maria José

2018-03-01

This paper presents the development of a polymer optical fiber (POF) strain gauge based on the light coupling principle, which the power attenuation is created by the misalignment between two POFs. The misalignment, in this case, is proportional to the strain on the structure that the fibers are attached. This principle has the advantages of low cost, ease of implementation, temperature insensitiveness, electromagnetic fields immunity and simplicity on the sensor interrogation and signal processing. Such advantages make the proposed solution an interesting alternative to the electronic strain gauges. For this reason, an analytical model for the POF strain gauge is proposed and validated. Furthermore, the proposed POF sensor is applied on an active orthosis for knee rehabilitation exercises through flexion/extension cycles. The controller of the orthosis provides 10 different levels of robotic assistance on the flexion/extension movement. The POF strain gauge is tested at each one of these levels. Results show good correlation between the optical and electronic strain gauges with root mean squared deviation (RMSD) of 1.87 Nm when all cycles are analyzed, which represents a deviation of less than 8%. For the application, the proposed sensor presented higher stability than the electronic one, which can provide advantages on the rehabilitation exercises and on the inner controller of the device.

Design and analysis of tactile optical sensor for endovascular surgery

NASA Astrophysics Data System (ADS)

Qasaimeh, M. A.; Dargahi, J.; Kahrizi, M.; Packirisamy, M.

2007-06-01

In this paper, design and Finite Element analysis of a new tactile optical sensor for the measurement of contact-pressure and tissue compliance in endovascular surgeries are presented. Using Micro-Electro-Mechanical-Systems (MEMS) technology, this sensor can be fabricated and integrated with the medical tools for endovascular surgeries such as Catheter tool. The designed sensor is capable of detecting the magnitude of the applied forces, the pressure distribution on contact objects, and also estimating the compliance of the contact tissue. The designed sensor is made of three layers, the upper layer is fabricated from monocrystalline silicon to form silicon membranes, the middle layer which is the supporting element is fabricated from both silicon and silicone rubber as a soft material and the lower layer is a supporting Plexiglas substrate to connect the designed sensor to the optical fibers. Simulation results show that for the given contact forces, the magnitude and the distribution of contacting tissues pressure along with tissue compliance can be determined. This sensor as proposed is a good candidate for batch micromachining, which is yet another commercial advantage for this design. Because of its less expensive cost, the surgeon can use it as a disposal part of the endovascular tools, requiring no re-sterilization and reducing the cost of surgery.

Spatially distributed fiber sensor with dual processed outputs

NASA Astrophysics Data System (ADS)

Xu, X.; Spillman, William B., Jr.; Claus, Richard O.; Meissner, K. E.; Chen, K.

2005-05-01

Given the rapid aging of the world"s population, improvements in technology for automation of patient care and documentation are badly needed. We have previously demonstrated a 'smart bed' that can non-intrusively monitor a patient in bed and determine a patient's respiration, heart rate and movement without intrusive or restrictive medical measurements. This is an application of spatially distributed integrating fiber optic sensors. The basic concept is that any patient movement that also moves an optical fiber within a specified area will produce a change in the optical signal. Two modal modulation approaches were considered, a statistical mode (STM) sensor and a high order mode excitation (HOME) sensor. The present design includes an STM sensor combined with a HOME sensor, using both modal modulation approaches. A special lens system allows only the high order modes of the optical fiber to be excited and coupled into the sensor. For handling output from the dual STM-HOME sensor, computer processing methods are discussed that offer comprehensive perturbation analysis for more reliable patient monitoring.

Miniature all-silica optical fiber pressure sensor with an ultrathin uniform diaphragm.

PubMed

Wang, Wenhui; Wu, Nan; Tian, Ye; Niezrecki, Christopher; Wang, Xingwei

2010-04-26

This paper presents an all-silica miniature optical fiber pressure/acoustic sensor based on the Fabry-Perot (FP) interferometric principle. The endface of the etched optical fiber tip and silica thin diaphragm on it form the FP structure. The uniform and thin silica diaphragm was fabricated by etching away the silicon substrate from a commercial silicon wafer that has a thermal oxide layer. The thin film was directly thermally bonded to the endface of the optical fiber thus creating the Fabry-Perot cavity. Thin films with a thickness from 1microm to 3microm have been bonded successfully. The sensor shows good linearity and hysteresis during measurement. A sensor with 0.75 microm-thick diaphragm thinned by post silica etching was demonstrated to have a sensitivity of 11 nm/kPa. The new sensor has great potential to be used as a non-intrusive pressure sensor in a variety of sensing applications.

Two-wavelength quadrature multipoint detection of partial discharge in power transformers using fiber Fabry-Perot acoustic sensors

NASA Astrophysics Data System (ADS)

Dong, Bo; Han, Ming; Wang, Anbo

2012-06-01

A reliable and low-cost two-wavelength quadrature interrogating method has been developed to demodulate optical signals from diaphragm-based Fabry-Perot interferometric fiber optic sensors for multipoint partial discharge detection in power transformers. Commercial available fused-silica parts (a wafer, a fiber ferrule, and a mating sleeve) and a cleaved optical single mode fiber were bonded together to form an extrinsic Fabry-Perot acoustic sensor. Two lasers with center wavelengths separated by a quarter of the period of sensor interference fringes were used to probe acousticwave- induced diaphragm vibration. A coarse wavelength-division multiplexing (CWDM) add/drop multiplexer was used to separate the reflected two wavelengths before two photo detectors. Optical couplers were used to distribute mixed laser light to each sensor-detector module for multiplexing purpose. Sensor structure, detection system design and experiment results are presented.

Volatile Organic Compound Optical Fiber Sensors: A Review

PubMed Central

Elosua, Cesar; Matias, Ignacio R.; Bariain, Candido; Arregui, Francisco J.

2006-01-01

Volatile organic compound (VOC) detection is a topic of growing interest with applications in diverse fields, ranging from environmental uses to the food or chemical industries. Optical fiber VOC sensors offering new and interesting properties which overcame some of the inconveniences found on traditional gas sensors appeared over two decades ago. Thanks to its minimum invasive nature and the advantages that optical fiber offers such as light weight, passive nature, low attenuation and the possibility of multiplexing, among others, these sensors are a real alternative to electronic ones in electrically noisy environments where electronic sensors cannot operate correctly. In the present work, a classification of these devices has been made according to the sensing mechanism and taking also into account the sensing materials or the different methods of fabrication. In addition, some solutions already implemented for the detection of VOCs using optical fiber sensors will be described with detail.

An optical fiber infrasound sensor: a new lower limit on atmospheric pressure noise between 1 and 10 Hz.

PubMed

Zumberge, Mark A; Berger, Jonathan; Hedlin, Michael A H; Husmann, Eric; Nooner, Scott; Hilt, Richard; Widmer-Schnidrig, Rudolf

2003-05-01

A new distributed sensor for detecting pressure variations caused by distant sources has been developed. The instrument reduces noise due to air turbulence in the infrasound band by averaging pressure along a line by means of monitoring strain in a long tubular diaphragm with an optical fiber interferometer. Above 1 Hz, the optical fiber infrasound sensor (OFIS) is less noisy than sensors relying on mechanical filters. Records collected from an 89-m-long OFS indicate a new low noise limit in the band from 1 to 10 Hz. Because the OFIS integrates pressure variations at light-speed rather than the speed of sound, phase delays of the acoustical signals caused by the sensor are negligible. Very long fiber-optic sensors are feasible and hold the promise of better wind-noise reduction than can be achieved with acoustical-mechanical systems.

Hairlike Percutaneous Photochemical Sensors

NASA Technical Reports Server (NTRS)

George, Thomas; Loeb, Gerald

2004-01-01

Instrumentation systems based on hairlike fiber-optic photochemical sensors have been proposed as minimally invasive means of detecting biochemicals associated with cancer and other diseases. The fiber-optic sensors could be mass-produced as inexpensive, disposable components. The sensory tip of a fiber-optic sensor would be injected through the patient's skin into subcutaneous tissue. A biosensing material on the sensory tip would bind or otherwise react with the biochemical(s) of interest [the analyte(s)] to produce a change in optical properties that would be measured by use of an external photonic analyzer. After use, a fiber-optic sensor could be simply removed by plucking it out with tweezers. A fiber-optic sensor according to the proposal would be of the approximate size and shape of a human hair, and its sensory tip would resemble a follicle. Once inserted into a patient's subcutaneous tissue, the sensor would even more closely resemble a hair growing from a follicle (see Figure 1). The biosensing material on the sensory tip could consist of a chemical and/or cells cultured and modified for the purpose. The biosensing material would be contained within a membrane that would cover the tip. If the membrane were not permeable by an analyte, then it would be necessary to create pores in the membrane that would be large enough to allow analyte molecules to diffuse to the biosensing material, but not so large as to allow cells (if present as part of the biosensing material) to diffuse out. The end of the fiber-optic sensor opposite the sensory tip would be inserted in a fiberoptic socket in the photonic analyzer.

Fiber-optic photoelastic pressure sensor with fiber-loss compensation

NASA Technical Reports Server (NTRS)

Beheim, G.; Anthan, D. J.

1987-01-01

A new fiber-optic pressure sensor is described that has high immunity to the effects of fiber-loss variations. This device uses the photoelastic effect to modulate the proportion of the light from each of two input fibers that is coupled into each of two output fibers. This four-fiber link permits two detectors to be used to measure the sensor's responses to the light from each of two independently controlled sources. These four detector outputs are processed to yield a loss-compensated signal that is a stable and sensitive pressure indicator.

Micro optical fiber light source and sensor and method of fabrication thereof

DOEpatents

Kopelman, Raoul; Tan, Weihong; Shi, Zhong-You

1994-01-01

This invention relates generally to the development of and a method of fabricating a micro optical fiber light source. An optical fiber micro-light source is presented whose aperture is extremely small yet able to act as an intense light source. Light sources of this type have wide ranging applications, including use as micro-sensors in NSOM. Micro-sensor light sources have excellent detection limits as well as photo stability, reversibility, and millisecond response times. Furthermore, a method for manufacturing a micro optical fiber light source is provided. It involves the photo-chemical attachment of an optically active material onto the end surface of an optical fiber cable which has been pulled to form an end with an extremely narrow aperture. More specifically, photopolymerization has been applied as a means to photo-chemically attach an optically active material. This process allows significant control of the size of the micro light source. Furthermore, photo-chemically attaching an optically active material enables the implementation of the micro-light source in a variety of sensor applications.

Micro optical fiber light source and sensor and method of fabrication thereof

DOEpatents

Kopelman, R.; Tan, W.; Shi, Z.Y.

1994-11-01

This invention relates generally to the development of and a method of fabricating a micro optical fiber light source. An optical fiber micro-light source is presented whose aperture is extremely small yet able to act as an intense light source. Light sources of this type have wide ranging applications, including use as micro-sensors in NSOM. Micro-sensor light sources have excellent detection limits as well as photo stability, reversibility, and millisecond response times. Furthermore, a method for manufacturing a micro optical fiber light source is provided. It involves the photo-chemical attachment of an optically active material onto the end surface of an optical fiber cable which has been pulled to form an end with an extremely narrow aperture. More specifically, photopolymerization has been applied as a means to photo-chemically attach an optically active material. This process allows significant control of the size of the micro light source. Furthermore, photo-chemically attaching an optically active material enables the implementation of the micro-light source in a variety of sensor applications. 4 figs.

Fiber-Optic Temperature Sensor Using a Thin-Film Fabry-Perot Interferometer

NASA Technical Reports Server (NTRS)

Beheim, Glenn

1997-01-01

A fiber-optic temperature sensor was developed that is rugged, compact, stable, and can be inexpensively fabricated. This thin-film interferometric temperature sensor was shown to be capable of providing a +/- 2 C accuracy over the range of -55 to 275 C, throughout a 5000 hr operating life. A temperature-sensitive thin-film Fabry-Perot interferometer can be deposited directly onto the end of a multimode optical fiber. This batch-fabricatable sensor can be manufactured at a much lower cost than can a presently available sensor, which requires the mechanical attachment of a Fabry-Perot interferometer to a fiber. The principal disadvantage of the thin-film sensor is its inherent instability, due to the low processing temperatures that must be used to prevent degradation of the optical fiber's buffer coating. The design of the stable thin-film temperature sensor considered the potential sources of both short and long term drifts. The temperature- sensitive Fabry-Perot interferometer was a silicon film with a thickness of approx. 2 microns. A laser-annealing process was developed which crystallized the silicon film without damaging the optical fiber. The silicon film was encapsulated with a thin layer of Si3N4 over coated with aluminum. Crystallization of the silicon and its encapsulation with a highly stable, impermeable thin-film structure were essential steps in producing a sensor with the required long-term stability.

Measurement of Cerenkov radiation induced by the gamma-rays of Co-60 therapy units using wavelength shifting fiber.

PubMed

Jang, Kyoung Won; Shin, Sang Hun; Kim, Seon Geun; Kim, Jae Seok; Yoo, Wook Jae; Ji, Young Hoon; Lee, Bongsoo

2014-04-21

In this study, a wavelength shifting fiber that shifts ultra-violet and blue light to green light was employed as a sensor probe of a fiber-optic Cerenkov radiation sensor. In order to characterize Cerenkov radiation generated in the developed wavelength shifting fiber and a plastic optical fiber, spectra and intensities of Cerenkov radiation were measured with a spectrometer. The spectral peaks of light outputs from the wavelength shifting fiber and the plastic optical fiber were measured at wavelengths of 500 and 510 nm, respectively, and the intensity of transmitted light output of the wavelength shifting fiber was 22.2 times higher than that of the plastic optical fiber. Also, electron fluxes and total energy depositions of gamma-ray beams generated from a Co-60 therapy unit were calculated according to water depths using the Monte Carlo N-particle transport code. The relationship between the fluxes of electrons over the Cerenkov threshold energy and the energy depositions of gamma-ray beams from the Co-60 unit is a near-identity function. Finally, percentage depth doses for the gamma-ray beams were obtained using the fiber-optic Cerenkov radiation sensor, and the results were compared with those obtained by an ionization chamber. The average dose difference between the results of the fiber-optic Cerenkov radiation sensor and those of the ionization chamber was about 2.09%.

Research of distributed-fiber-optic pressure sensor

NASA Astrophysics Data System (ADS)

Lu, Xiao Ming; Ren, Xin; Chen, Yu-bao; Che, Rensheng

1991-08-01

The paper discribed the principle and method of distributed fiber optic pressure sensor utilizing OTDR technique. The relativity of the microbend loss and bend radius of the multimode optical fiber is discussed ,and its experimental curve is given. In this paper ,a new type of OTDR measuring system using single-chip microcomputer is introduced as well

Self-compensating fiber optic flow sensor having an end of a fiber optics element and a reflective surface within a tube

DOEpatents

Peng, Wei; Qi, Bing; Wang, Anbo

2006-05-16

A flow rate fiber optic transducer is made self-compensating for both temperature and pressure by using preferably well-matched integral Fabry-Perot sensors symmetrically located around a cantilever-like structure. Common mode rejection signal processing of the outputs allows substantially all effects of both temperature and pressure to be compensated. Additionally, the integral sensors can individually be made insensitive to temperature.

Multi-channel fiber optic dew and humidity sensor

NASA Astrophysics Data System (ADS)

Limodehi, Hamid E.; Mozafari, Morteza; Amiri, Hesam; Légaré, François

2018-03-01

In this article, we introduce a multi-channel fiber optic dew and humidity sensor which works using a novel method based on relation between surface plasmon resonance (SPR) and water vapor condensation. The proposed sensor can instantly detect moisture or dew formation through its fiber optic channels, separately situated in different places. It enables to simultaneously measure the ambient Relative Humidity (RH) and dew point temperature of several environments with accuracy of 5%.

Preparation and measurement of FBG-based length, temperature, and vibration sensors

NASA Astrophysics Data System (ADS)

Mikel, Bretislav; Helan, Radek; Buchta, Zdenek; Jelinek, Michal; Cip, Ondrej

2016-12-01

We present system of structure health measurement by optical fiber sensors based on fiber Bragg gratings. Our system is focused to additionally install to existing buildings. We prepared first set-up of the system to monitoring of the nuclear power plant containment shape deformation. The presented system can measure up to several tens of sensors simultaneously. Each sensor contains optical fiber grating to measurement of change of length and the other independed fiber grating to monitor the temperature and the other ineligible effects.

Fiber-optic sensors for aerospace electrical measurements: An update

NASA Technical Reports Server (NTRS)

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

1991-01-01

Fiber-optic sensors are being developed for electrical current, voltage, and power measurements in aerospace applications. These sensors are presently designed to cover ac frequencies from 60 Hz to 20 kHz. The current sensor, based on the Faraday effect in optical fiber, is in advanced development after some initial testing. Concentration is on packaging methods and ways to maintain consistent sensitivity with changes in temperature. The voltage sensor, utilizing the Pockels effect in a crystal, has excelled in temperature tests. This paper reports on the development of these sensors, the results of evaluation, improvements now in progress, and the future direction of the work.

Three-Axis Distributed Fiber Optic Strain Measurement in 3D Woven Composite Structures

NASA Technical Reports Server (NTRS)

Castellucci, Matt; Klute, Sandra; Lally, Evan M.; Froggatt, Mark E.; Lowry, David

2013-01-01

Recent advancements in composite materials technologies have broken further from traditional designs and require advanced instrumentation and analysis capabilities. Success or failure is highly dependent on design analysis and manufacturing processes. By monitoring smart structures throughout manufacturing and service life, residual and operational stresses can be assessed and structural integrity maintained. Composite smart structures can be manufactured by integrating fiber optic sensors into existing composite materials processes such as ply layup, filament winding and three-dimensional weaving. In this work optical fiber was integrated into 3D woven composite parts at a commercial woven products manufacturing facility. The fiber was then used to monitor the structures during a VARTM manufacturing process, and subsequent static and dynamic testing. Low cost telecommunications-grade optical fiber acts as the sensor using a high resolution commercial Optical Frequency Domain Reflectometer (OFDR) system providing distributed strain measurement at spatial resolutions as low as 2mm. Strain measurements using the optical fiber sensors are correlated to resistive strain gage measurements during static structural loading. Keywords: fiber optic, distributed strain sensing, Rayleigh scatter, optical frequency domain reflectometry

Fabrication and Analysis Signal Optical Fiber Sensor Based On Bend Loss for Weight in Motion Applications

NASA Astrophysics Data System (ADS)

Aftah Syukron, Ahmad; Marzuki, Ahmad; Setyawan, Ary

2017-11-01

Road network plays very important role in economic development. Overweight is one of the main factors contributing to road damage. To minimize this factor, road authority has to make sure that all vehicles operate in according to maximum vehicle regulation set by the government. The one solution can use from this problem is Weight in motion (WIM) technology. WIM technology allows measuring vehicle weight quickly. The sensor is one of the important components in the WIM system. This paper presents a model of WIM fiber sensor work based on bend loss. Fiber sensor has made by coiling optical fiber. Coiling optical fiber has managed in the elliptical shape rubber coil. Rubber coil then is planted in the pad of sensor. The principle of this sensor is a detecting of the shift light intensity output of optical fiber when the vehicles a passing through on fiber sensor. Loading was carried out using loaded truck model. Data was carried out with variations of load and load positions in the truck. The results can be concluded that the shift light intensity is greater with the more shift loads. The loader of the truck has also resulted in the greater loss. Loads in the truck distributed on the axles due to the position of loads.

In situ simultaneous strain and temperature measurement of adaptive composite materials using a fiber Bragg grating based sensor

NASA Astrophysics Data System (ADS)

Yoon, Hyuk-Jin; Costantini, Daniele M.; Michaud, Veronique; Limberger, Hans G.; Manson, Jan-Anders; Salathe, Rene P.; Kim, Chun-Gon; Hong, Chang-Sun

2005-05-01

An optical fiber sensor to simultaneously measure strain and temperature was designed and embedded into an adaptive composite laminate which exhibits a shape change upon thermal activation. The sensor is formed by two fiber Bragg gratings, which are written in optical fibers with different core dopants. The two gratings were spliced close to each other and a sensing element resulted with Bragg gratings of similar strain sensitivity but different response to temperature. This is due to the dependence of the fiber thermo-optic coefficient on core dopants and relative concentrations. The sensor was tested on an adaptive composite laminate made of unidirectional Kevlar-epoxy pre-preg plies. Several 150μm diameter pre-strained NiTiCu shape memory alloy wires were embedded in the composite laminate together with one fiber sensor. Simultaneous monitoring of strain and temperature during the curing process and activation in an oven was demonstrated.

Polarization Dependence Suppression of Optical Fiber Grating Sensor in a π-Shifted Sagnac Loop Interferometer

PubMed Central

Son, Jaebum; Lee, Min-Kyoung; Jeong, Myung Yung; Kim, Chang-Seok

2010-01-01

In the sensing applications of optical fiber grating, it is necessary to reduce the transmission-type polarization dependence to isolate the sensing parameter. It is experimentally shown that the polarization-dependent spectrum of acousto-optic long-period fiber grating sensors can be suppressed in the transmission port of a π-shifted Sagnac loop interferometer. General expressions for the transmittance and reflectance are derived for transmission-type, reflection-type, and partially reflecting/transmitting-type polarization-dependent optical devices. The compensation of polarization dependence through the counter propagation in the Sagnac loop interferometer is quantitatively measured for a commercial in-line polarizer and an acousto-optic long-period fiber grating sensor. PMID:22399884

A microvolume molecularly imprinted polymer modified fiber-optic evanescent wave sensor for bisphenol A determination.

PubMed

Xiong, Yan; Ye, Zhongbin; Xu, Jing; Liu, Yucheng; Zhang, Hanyin

2014-04-01

A fiber-optic evanescent wave sensor for bisphenol A (BPA) determination based on a molecularly imprinted polymer (MIP)-modified fiber column was developed. MIP film immobilized with BPA was synthesized on the fiber column, and the sensor was then constructed by inserting the optical fiber prepared into a transparent capillary. A microchannel (about 2.0 μL) formed between the fiber and the capillary acted as a flow cell. BPA can be selectively adsorbed online by the MIP film and excited to produce fluorescence by the evanescent wave produced on the fiber core surface. The conditions for BPA enrichment, elution, and fluorescence detection are discussed in detail. The analytical measurements were made at 276 nm/306 nm (λ(ex)/λ(em)), and linearity of 3 × 10(-9)-5 × 10(-6) g mL(-1) BPA, a limit of detection of 1.7 × 10(-9) g mL(-1) BPA (3σ), and a relative standard deviation of 2.4% (n = 5) were obtained. The sensor selectivity and MIP binding measurement were also evaluated. The results indicated that the selectivity and sensitivity of the proposed fiber-optic sensor could be greatly improved by using MIP as a recognition and enrichment element. Further, by modification of the sensing and detection elements on the optical fiber, the proposed sensor showed the advantages of easy fabrication and low cost. The novel sensor configuration provided a platform for monitoring other species by simply changing the light source and sensing elements. The sensor presented has been successfully applied to determine BPA released from plastic products treated at different temperatures.

Refractive-index-sensing fiber comb using intracavity multi-mode interference fiber sensor

NASA Astrophysics Data System (ADS)

Oe, Ryo; Minamikawa, Takeo; Taue, Shuji; Fukano, Hideki; Nakajima, Yoshiaki; Minoshima, Kaoru; Yasui, Takeshi

2018-02-01

Refractive index measurement is important for evaluation of liquid materials, optical components, and bio sensing. One promising approach for such measurement is use of optical fiber sensors such as surface plasmonic resonance or multi-mode interference (MMI), which measure the change of optical spectrum resulting from the refractive index change. However, the precision of refractive index measurement is limited by the performance of optical spectrum analyzer. If such the refractive index measurement can be performed in radio frequency (RF) region in place of optical region, the measurement precision will be further improved by the frequency-standard-based RF measurement. To this end, we focus on the disturbance-to-RF conversion in a fiber optical frequency comb (OFC) cavity. Since frequency spacing frep of OFC depends on an optical cavity length nL, frep sensitively reflects the external disturbance interacted with nL. Although we previously demonstrated the precise strain measurement based on the frep measurement, the measurable physical quantity is limited to strain or temperature, which directly interacts with the fiber cavity itself. If a functional fiber sensor can be installed into the fiber OFC cavity, the measurable physical quantity will be largely expanded. In this paper, we introduce a MMI fiber sensor into a ring-type fiber OFC cavity for refractive index measurement. We confirmed the refractive-index-dependent frep shift.

Electro-optic architecture for servicing sensors and actuators in advanced aircraft propulsion systems

NASA Technical Reports Server (NTRS)

Poppel, G. L.; Glasheen, W. M.

1989-01-01

A detailed design of a fiber optic propulsion control system, integrating favored sensors and electro-optics architecture is presented. Layouts, schematics, and sensor lists describe an advanced fighter engine system model. Components and attributes of candidate fiber optic sensors are identified, and evaluation criteria are used in a trade study resulting in favored sensors for each measurand. System architectural ground rules were applied to accomplish an electro-optics architecture for the favored sensors. A key result was a considerable reduction in signal conductors. Drawings, schematics, specifications, and printed circuit board layouts describe the detailed system design, including application of a planar optical waveguide interface.

Relative hardness measurement of soft objects by a new fiber optic sensor

NASA Astrophysics Data System (ADS)

Ahmadi, Roozbeh; Ashtaputre, Pranav; Abou Ziki, Jana; Dargahi, Javad; Packirisamy, Muthukumaran

2010-06-01

The measurement of relative hardness of soft objects enables replication of human finger tactile perception capabilities. This ability has many applications not only in automation and robotics industry but also in many other areas such as aerospace and robotic surgery where a robotic tool interacts with a soft contact object. One of the practical examples of interaction between a solid robotic instrument and a soft contact object occurs during robotically-assisted minimally invasive surgery. Measuring the relative hardness of bio-tissue, while contacting the robotic instrument, helps the surgeons to perform this type of surgery more reliably. In the present work, a new optical sensor is proposed to measure the relative hardness of contact objects. In order to measure the hardness of a contact object, like a human finger, it is required to apply a small force/deformation to the object by a tactile sensor. Then, the applied force and resulting deformation should be recorded at certain points to enable the relative hardness measurement. In this work, force/deformation data for a contact object is recorded at certain points by the proposed optical sensor. Recorded data is used to measure the relative hardness of soft objects. Based on the proposed design, an experimental setup was developed and experimental tests were performed to measure the relative hardness of elastomeric materials. Experimental results verify the ability of the proposed optical sensor to measure the relative hardness of elastomeric samples.

The early history of the closed loop fiber optic gyro and derivative sensors at McDonnell Douglas, Blue Road Research and Columbia Gorge Research

NASA Astrophysics Data System (ADS)

Udd, Eric

2016-05-01

On September 29, 1977 the first written disclosure of a closed loop fiber optic gyro was witnessed and signed off by four people at McDonnell Douglas Astronautics Company in Huntington Beach, California. Over the next ten years a breadboard demonstration unit, and several prototypes were built. In 1987 the fundamental patent for closed loop operation began a McDonnell Douglas worldwide licensing process. Internal fiber optic efforts were redirected to derivative sensors and inventions. This included development of acoustic, strain and distributed sensors as well as a Sagnac interferometer based secure fiber optic communication system and the new field of fiber optic smart structures. This paper provides an overview of these activities and transitions.

Dual spherical single-mode-multimode-single-mode optical fiber temperature sensor based on a Mach–Zehnder interferometer

NASA Astrophysics Data System (ADS)

Tan, Jianchang; Feng, Guoying; Zhang, Shulin; Liang, Jingchuan; Li, Wei; Luo, Yun

2018-07-01

A dual spherical single-mode-multimode-single-mode (DSSMS) optical fiber temperature sensor based on a Mach–Zehnder interferometer (MZI) was designed and implemented in this paper. Theoretical and experimental results indicated that the LP01 mode in the core and the LP09 mode excited by the spherical structure were maintained and transmitted via multimode fiber and interfered at the second spherical structure, resulting in the interference spectrum. An increase or decrease in temperature can cause significant red-shift or blue-shift of the spectrum, respectively. The linearity of the spectral shift due to the temperature change is ~0.999, the sensitivity at 30 °C–540 °C is ~37.372 pm °C‑3, and at  ‑25 °C–25 °C is ~37.28 pm °C‑1. The reproducibility error of this all-fiber temperature sensor at 30 °C–540 °C is less than 0.15%. Compared with the optical fiber sensor with a tapered structure and fiber core offset structure, this MZI-based DSSMS optical fiber temperature sensor has higher mechanical strength. Moreover, benefiting from low-cost and environmentally friendly materials, it is expected to be a novel micro-nano all-fiber sensor.

Seismic damage identification using multi-line distributed fiber optic sensor system

NASA Astrophysics Data System (ADS)

Ou, Jinping; Hou, Shuang

2005-06-01

Determination of the actual nonlinear inelastic response mechanisms developed by civil structures such as buildings and bridges during strong earthquakes and post-earthquake damage assessment of these structures represent very difficult challenges for earthquake structural engineers. One of the main reasons is that the traditional sensor can't serve for such a long period to cover an earthquake and the seismic damage location in the structure can't be predicted in advance definitely. It is thought that the seismic damage of reinforced concrete (RC) structure can be related to the maximum response the structure, which can also be related to the cracks on the concrete. A distributed fiber optic sensor was developed to detect the cracks on the reinforced concrete structure under load. Fiber optic couples were used in the sensor system to extend the sensor system's capacity from one random point detection to more. An optical time domain reflectometer (OTDR) is employed for interrogation of the sensor signal. Fiber optic sensors are attached on the surface of the concrete by the epoxy glue. By choosing the strength of epoxy, the damage state of the concrete can be responded to the occurrence of the Fresnel scattering in the fiber optic sensor. Experiments involved monotonic loading to failure. Finally, the experimental results in terms of crack detection capability are presented and discussed.

Impurity-doped optical shock, detonation and damage location sensor

DOEpatents

Weiss, J.D.

1995-02-07

A shock, detonation, and damage location sensor providing continuous fiber-optic means of measuring shock speed and damage location, and could be designed through proper cabling to have virtually any desired crush pressure. The sensor has one or a plurality of parallel multimode optical fibers, or a singlemode fiber core, surrounded by an elongated cladding, doped along their entire length with impurities to fluoresce in response to light at a different wavelength entering one end of the fiber(s). The length of a fiber would be continuously shorted as it is progressively destroyed by a shock wave traveling parallel to its axis. The resulting backscattered and shifted light would eventually enter a detector and be converted into a proportional electrical signals which would be evaluated to determine shock velocity and damage location. The corresponding reduction in output, because of the shortening of the optical fibers, is used as it is received to determine the velocity and position of the shock front as a function of time. As a damage location sensor the sensor fiber cracks along with the structure to which it is mounted. The size of the resulting drop in detector output is indicative of the location of the crack. 8 figs.

Impurity-doped optical shock, detonation and damage location sensor

DOEpatents

Weiss, Jonathan D.

1995-01-01

A shock, detonation, and damage location sensor providing continuous fiber-optic means of measuring shock speed and damage location, and could be designed through proper cabling to have virtually any desired crush pressure. The sensor has one or a plurality of parallel multimode optical fibers, or a singlemode fiber core, surrounded by an elongated cladding, doped along their entire length with impurities to fluoresce in response to light at a different wavelength entering one end of the fiber(s). The length of a fiber would be continuously shorted as it is progressively destroyed by a shock wave traveling parallel to its axis. The resulting backscattered and shifted light would eventually enter a detector and be converted into a proportional electrical signals which would be evaluated to determine shock velocity and damage location. The corresponding reduction in output, because of the shortening of the optical fibers, is used as it is received to determine the velocity and position of the shock front as a function of time. As a damage location sensor the sensor fiber cracks along with the structure to which it is mounted. The size of the resulting drop in detector output is indicative of the location of the crack.

Monolithic fiber optic sensor assembly

DOEpatents

Sanders, Scott

2015-02-10

A remote sensor element for spectrographic measurements employs a monolithic assembly of one or two fiber optics to two optical elements separated by a supporting structure to allow the flow of gases or particulates therebetween. In a preferred embodiment, the sensor element components are fused ceramic to resist high temperatures and failure from large temperature changes.

Two-Channel SPR Sensor Combined Application of Polymer- and Vitreous-Clad Optic Fibers

PubMed Central

Wei, Yong; Su, Yudong; Liu, Chunlan; Nie, Xiangfei; Liu, Zhihai; Zhang, Yu; Zhang, Yonghui

2017-01-01

By combining a polymer-clad optic fiber and a vitreous-clad optic fiber, we proposed and fabricated a novel optic fiber surface plasmon resonance (SPR) sensor to conduct two-channel sensing at the same detection area. The traditional optic fiber SPR sensor has many disadvantages; for example, removing the cladding requires corrosion, operating it is dangerous, adjusting the dynamic response range is hard, and producing different resonance wavelengths in the sensing area to realize a multi-channel measurement is difficult. Therefore, in this paper, we skillfully used bare fiber grinding technology and reverse symmetry welding technology to remove the cladding in a multi-mode fiber and expose the evanescent field. On the basis of investigating the effect of the grinding angle on the dynamic range change of the SPR resonance valley wavelength and sensitivity, we combined polymer-clad fiber and vitreous-clad fiber by a smart design structure to realize at a single point a two-channel measurement fiber SPR sensor. In this paper, we obtained a beautiful spectral curve from a multi-mode fiber two-channel SPR sensor. In the detection range of the refractive rate between 1.333 RIU and 1.385 RIU, the resonance valley wavelength of channel Ⅰ shifted from 622 nm to 724 nm with a mean average sensitivity of 1961 nm/RIU and the resonance valley wavelength of channel Ⅱ shifted from 741 nm to 976 nm with a mean average sensitivity of 4519 nm/RIU. PMID:29232841

Two-Channel SPR Sensor Combined Application of Polymer- and Vitreous-Clad Optic Fibers.

PubMed

Wei, Yong; Su, Yudong; Liu, Chunlan; Nie, Xiangfei; Liu, Zhihai; Zhang, Yu; Zhang, Yonghui

2017-12-09

By combining a polymer-clad optic fiber and a vitreous-clad optic fiber, we proposed and fabricated a novel optic fiber surface plasmon resonance (SPR) sensor to conduct two-channel sensing at the same detection area. The traditional optic fiber SPR sensor has many disadvantages; for example, removing the cladding requires corrosion, operating it is dangerous, adjusting the dynamic response range is hard, and producing different resonance wavelengths in the sensing area to realize a multi-channel measurement is difficult. Therefore, in this paper, we skillfully used bare fiber grinding technology and reverse symmetry welding technology to remove the cladding in a multi-mode fiber and expose the evanescent field. On the basis of investigating the effect of the grinding angle on the dynamic range change of the SPR resonance valley wavelength and sensitivity, we combined polymer-clad fiber and vitreous-clad fiber by a smart design structure to realize at a single point a two-channel measurement fiber SPR sensor. In this paper, we obtained a beautiful spectral curve from a multi-mode fiber two-channel SPR sensor. In the detection range of the refractive rate between 1.333 RIU and 1.385 RIU, the resonance valley wavelength of channel Ⅰ shifted from 622 nm to 724 nm with a mean average sensitivity of 1961 nm/RIU and the resonance valley wavelength of channel Ⅱ shifted from 741 nm to 976 nm with a mean average sensitivity of 4519 nm/RIU.

High spatial resolution distributed optical fiber dynamic strain sensor with enhanced frequency and strain resolution.

PubMed

Masoudi, Ali; Newson, Trevor P

2017-01-15

A distributed optical fiber dynamic strain sensor with high spatial and frequency resolution is demonstrated. The sensor, which uses the ϕ-OTDR interrogation technique, exhibited a higher sensitivity thanks to an improved optical arrangement and a new signal processing procedure. The proposed sensing system is capable of fully quantifying multiple dynamic perturbations along a 5 km long sensing fiber with a frequency and spatial resolution of 5 Hz and 50 cm, respectively. The strain resolution of the sensor was measured to be 40 nε.

Application of Negative Curvature Hollow-Core Fiber in an Optical Fiber Sensor Setup for Multiphoton Spectroscopy

PubMed Central

Stawska, Hanna Izabela; Mazur, Leszek Mateusz; Kosolapov, Alexey; Kolyadin, Anton; Bereś-Pawlik, Elżbieta

2017-01-01

In this paper, an application of negative curvature hollow core fiber (NCHCF) in an all-fiber, multiphoton fluorescence sensor setup is presented. The dispersion parameter (D) of this fiber does not exceed the value of 5 ps/nm × km across the optical spectrum of (680–750) nm, making it well suited for the purpose of multiphoton excitation of biological fluorophores. Employing 1.5 m of this fiber in a simple, all-fiber sensor setup allows us to perform multiphoton experiments without any dispersion compensation methods. Multiphoton excitation of nicotinamide adenine dinucleotide (NADH) and flavin adenine dinucleotide (FAD) with this fiber shows a 6- and 9-fold increase, respectively, in the total fluorescence signal collected when compared with the commercial solution in the form of a hollow-core photonic band gap fiber (HCPBF). To the author’s best knowledge, this is the first time an NCHCF was used in an optical-fiber sensor setup for multiphoton fluorescence experiments. PMID:28984838

Application of Negative Curvature Hollow-Core Fiber in an Optical Fiber Sensor Setup for Multiphoton Spectroscopy.

PubMed

Popenda, Maciej Andrzej; Stawska, Hanna Izabela; Mazur, Leszek Mateusz; Jakubowski, Konrad; Kosolapov, Alexey; Kolyadin, Anton; Bereś-Pawlik, Elżbieta

2017-10-06

In this paper, an application of negative curvature hollow core fiber (NCHCF) in an all-fiber, multiphoton fluorescence sensor setup is presented. The dispersion parameter (D) of this fiber does not exceed the value of 5 ps/nm × km across the optical spectrum of (680-750) nm, making it well suited for the purpose of multiphoton excitation of biological fluorophores. Employing 1.5 m of this fiber in a simple, all-fiber sensor setup allows us to perform multiphoton experiments without any dispersion compensation methods. Multiphoton excitation of nicotinamide adenine dinucleotide (NADH) and flavin adenine dinucleotide (FAD) with this fiber shows a 6- and 9-fold increase, respectively, in the total fluorescence signal collected when compared with the commercial solution in the form of a hollow-core photonic band gap fiber (HCPBF). To the author's best knowledge, this is the first time an NCHCF was used in an optical-fiber sensor setup for multiphoton fluorescence experiments.

In-situ growth of AuNPs on WS2@U-bent optical fiber for evanescent wave absorption sensor

NASA Astrophysics Data System (ADS)

Zhang, Suzhen; Zhao, Yuefeng; Zhang, Chao; Jiang, Shouzhen; Yang, Cheng; Xiu, Xianwu; Li, Chonghui; Li, Zhen; Zhao, Xiaofei; Man, Baoyuan

2018-05-01

The sensitivity of the evanescent wave absorption sensor is always a hot topic which has been attracted researchers' discussion. It is still a challenge for developing the effective sensor to sensitively detect some biochemical molecules solution in a simple and low-cost way. In this paper, an evanescent wave absorption (EWA) sensor has been presented based on the U-bent multimode fiber coated with tungsten disulfide (WS2) film and in-situ growth of gold nanoparticles (AuNPs) for the detection of ethanol solution and sodium chloride (NaCl) solution. Benefitted from the effective light coupling produced between U-bent probe and AuNPs, we attained the optimal size of the AuNPs by changing the reaction time between WS2 and tetrachloroauric acid (HAuCl4). With the AuNPs/WS2@U-bent optical fiber, we discussed the behaviors of EWA sensor, such as sensitivity, reproducibility, fast response-recovery time and stability. The sensitivity (△A/△C) of the proposed AuNPs/WS2@U-bent optical fiber EWA sensor is 0.65 for the detection of the ethanol solution. Besides, the AuNPs/WS2@U-bent optical fiber EWA sensor exhibits high sensitivity in detection of the sodium chloride (NaCl), which can reach 1.5 when the proposed sensor was immersed into NaCl solution. Our work demonstrates that the U-bent optical fiber EWA sensor may have promising applications in testing the solution of concentration.

Fiber-Laser-Based Ultrasound Sensor for Photoacoustic Imaging

PubMed Central

Liang, Yizhi; Jin, Long; Wang, Lidai; Bai, Xue; Cheng, Linghao; Guan, Bai-Ou

2017-01-01

Photoacoustic imaging, especially for intravascular and endoscopic applications, requires ultrasound probes with miniature size and high sensitivity. In this paper, we present a new photoacoustic sensor based on a small-sized fiber laser. Incident ultrasound waves exert pressures on the optical fiber laser and induce harmonic vibrations of the fiber, which is detected by the frequency shift of the beating signal between the two orthogonal polarization modes in the fiber laser. This ultrasound sensor presents a noise-equivalent pressure of 40 Pa over a 50-MHz bandwidth. We demonstrate this new ultrasound sensor on an optical-resolution photoacoustic microscope. The axial and lateral resolutions are 48 μm and 3.3 μm. The field of view is up to 1.57 mm2. The sensor exhibits strong resistance to environmental perturbations, such as temperature changes, due to common-mode cancellation between the two orthogonal modes. The present fiber laser ultrasound sensor offers a new tool for all-optical photoacoustic imaging. PMID:28098201

Highly-hermetic feedthrough fiber pigtailed circular TO-can electro-optic sensor for avionics applications

NASA Astrophysics Data System (ADS)

Lauzon, Jocelyn; Leduc, Lorrain; Bessette, Daniel; Bélanger, Nicolas

2012-06-01

Electro-optic sensors made of lasers or photodetectors assemblies can be associated with a window interface. In order to use these sensors in an avionics application, this interface has to be set on the periphery of the aircraft. This creates constraints on both the position/access of the associated electronics circuit card and the aircraft fuselage. Using an optical fiber to guide the light signal to a sensor being situated inside the aircraft where electronics circuit cards are deployed is an obvious solution that can be readily available. Fiber collimators that adapt to circular TO-can type window sensors do exist. However, they are bulky, add weight to the sensor and necessitate regular maintenance of the optical interface since both the sensor window and the collimator end-face are unprotected against contamination. Such maintenance can be complex since the access to the electronics circuit card, where the sensor is sitting, is usually difficult. This interface alignment can also be affected by vibrations and mechanical shocks, thus impacting sensor performances. As a solution to this problem, we propose a highly-hermetic feedthrough fiber pigtailed circular TO-can package. The optical element to optical fiber interface being set inside the hermetic package, there is no risk of contamination and thus, such a component does not require any maintenance. The footprint of these sensors being identical to their window counterparts, they offer drop-in replacement opportunities. Moreover, we have validated such packaged electro-optic sensors can be made to operate between -55 to 115°C, sustain 250 temperature cycles, 1500G mechanical shocks, 20Grms random vibrations without any performance degradations. Their water content is much smaller than the 0.5% limit set by MIL-STD-883, Method 1018. They have also been verified to offer a fiber pigtail strain relief resistance over 400g. Depending on the electronics elements inside these sensors, they can be made to have a MTBF over 50 000h at 100°C.

An In-situ Real-Time Optical Fiber Sensor Based on Surface Plasmon Resonance for Monitoring the Growth of TiO2 Thin Films

PubMed Central

Tsao, Yu-Chia; Tsai, Woo-Hu; Shih, Wen-Ching; Wu, Mu-Shiang

2013-01-01

An optical fiber sensor based on surface plasmon resonance (SPR) is proposed for monitoring the thickness of deposited nano-thin films. A side-polished multimode SPR optical fiber sensor with an 850 nm-LD is used as the transducing element for real-time monitoring of the deposited TiO2 thin films. The SPR optical fiber sensor was installed in the TiO2 sputtering system in order to measure the thickness of the deposited sample during TiO2 deposition. The SPR response declined in real-time in relation to the growth of the thickness of the TiO2 thin film. Our results show the same trend of the SPR response in real-time and in spectra taken before and after deposition. The SPR transmitted intensity changes by approximately 18.76% corresponding to 50 nm of deposited TiO2 thin film. We have shown that optical fiber sensors utilizing SPR have the potential for real-time monitoring of the SPR technology of nanometer film thickness. The compact size of the SPR fiber sensor enables it to be positioned inside the deposition chamber, and it could thus measure the film thickness directly in real-time. This technology also has potential application for monitoring the deposition of other materials. Moreover, in-situ real-time SPR optical fiber sensor technology is in inexpensive, disposable technique that has anti-interference properties, and the potential to enable on-line monitoring and monitoring of organic coatings. PMID:23881144

An in-situ real-time optical fiber sensor based on surface plasmon resonance for monitoring the growth of TiO2 thin films.

PubMed

Tsao, Yu-Chia; Tsai, Woo-Hu; Shih, Wen-Ching; Wu, Mu-Shiang

2013-07-23

An optical fiber sensor based on surface plasmon resonance (SPR) is proposed for monitoring the thickness of deposited nano-thin films. A side-polished multimode SPR optical fiber sensor with an 850 nm-LD is used as the transducing element for real-time monitoring of the deposited TiO2 thin films. The SPR optical fiber sensor was installed in the TiO2 sputtering system in order to measure the thickness of the deposited sample during TiO2 deposition. The SPR response declined in real-time in relation to the growth of the thickness of the TiO2 thin film. Our results show the same trend of the SPR response in real-time and in spectra taken before and after deposition. The SPR transmitted intensity changes by approximately 18.76% corresponding to 50 nm of deposited TiO2 thin film. We have shown that optical fiber sensors utilizing SPR have the potential for real-time monitoring of the SPR technology of nanometer film thickness. The compact size of the SPR fiber sensor enables it to be positioned inside the deposition chamber, and it could thus measure the film thickness directly in real-time. This technology also has potential application for monitoring the deposition of other materials. Moreover, in-situ real-time SPR optical fiber sensor technology is in inexpensive, disposable technique that has anti-interference properties, and the potential to enable on-line monitoring and monitoring of organic coatings.

Turbidimeter Design and Analysis: A Review on Optical Fiber Sensors for the Measurement of Water Turbidity

PubMed Central

Omar, Ahmad Fairuz Bin; MatJafri, Mohd Zubir Bin

2009-01-01

Turbidimeters operate based on the optical phenomena that occur when incident light through water body is scattered by the existence of foreign particles which are suspended within it. This review paper elaborates on the standards and factors that may influence the measurement of turbidity. The discussion also focuses on the optical fiber sensor technologies that have been applied within the lab and field environment and have been implemented in the measurement of water turbidity and concentration of particles. This paper also discusses and compares results from three different turbidimeter designs that use various optical components. Mohd Zubir and Bashah and Daraigan have introduced a design which has simple configurations. Omar and MatJafri, on the other hand, have established a new turbidimeter design that makes use of optical fiber cable as the light transferring medium. The application of fiber optic cable to the turbidimeter will present a flexible measurement technique, allowing measurements to be made online. Scattered light measurement through optical fiber cable requires a highly sensitive detector to interpret the scattered light signal. This has made the optical fiber system have higher sensitivity in measuring turbidity compared to the other two simple turbidimeters presented in this paper. Fiber optic sensors provide the potential for increased sensitivity over large concentration ranges. However, many challenges must be examined to develop sensors that can collect reliable turbidity measurements in situ. PMID:22408507

A novel fiber optic sensor for the measurement of pH of blood based on colorimetry

NASA Astrophysics Data System (ADS)

Chaudhari, A. L.; Patil, D. D.; Shaligram, Arvind D.

2005-04-01

Fiber optic sensors designed to the date are largely based on monitoring the absorption change of several immobilized indicators or change in fluorescence of fluorometric indicators. The present paper reports a new type of fiber optic sensor for the measurement of blood pH based on Colorimetric principle. The sensor consists of two multimode step index fibers, mirror as reflector and blood serum with universal indicator as medium. LED is used as source and photodiode as detector. The intensity of color produced due to addition of indicator to blood serum depends upon hydrogen ion concentration. The output intensity from receiving fiber is measured as a function of pH of blood. The developed sensor is calibrated against the standard pH meter. The design, construction and calibration details are presented in paper.

Indium oxide based fiber optic SPR sensor

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shukla, Sarika; Sharma, Navneet K., E-mail: navneetk.sharma@jiit.ac.in

2016-05-06

Surface plasmon resonance based fiber optic sensor using indium oxide layer is presented and theoretically studied. It has been found that with increase in thickness of indium oxide layer beyond 170 nm, the sensitivity of SPR sensor decreases. 170 nm thick indium oxide layer based SPR sensor holds maximum sensitivity.

Combined imaging and chemical sensing using a single optical imaging fiber.

PubMed

Bronk, K S; Michael, K L; Pantano, P; Walt, D R

1995-09-01

Despite many innovations and developments in the field of fiber-optic chemical sensors, optical fibers have not been employed to both view a sample and concurrently detect an analyte of interest. While chemical sensors employing a single optical fiber or a noncoherent fiberoptic bundle have been applied to a wide variety of analytical determinations, they cannot be used for imaging. Similarly, coherent imaging fibers have been employed only for their originally intended purpose, image transmission. We herein report a new technique for viewing a sample and measuring surface chemical concentrations that employs a coherent imaging fiber. The method is based on the deposition of a thin, analyte-sensitive polymer layer on the distal surface of a 350-microns-diameter imaging fiber. We present results from a pH sensor array and an acetylcholine biosensor array, each of which contains approximately 6000 optical sensors. The acetylcholine biosensor has a detection limit of 35 microM and a fast (< 1 s) response time. In association with an epifluorescence microscope and a charge-coupled device, these modified imaging fibers can display visual information of a remote sample with 4-microns spatial resolution, allowing for alternating acquisition of both chemical analysis and visual histology.

Optical sensors and multiplexing for aircraft engine control

NASA Astrophysics Data System (ADS)

Berkcan, Ertugrul

1993-02-01

Time division multiplexing of spectral modulation fiber optic sensors for aircraft engine control is presented. The paper addresses the architectural properties, the accuracy, the benefits and problems of different type of sources, the spectral stability and update times using these sources, the size, weight, and power issues, and finally the technology needs regarding FADEC mountability. The fiber optic sensors include temperature, pressure, and position spectral modulation sensors.

Analysis of LPFG sensor systems for aircraft wing drag optimization

NASA Astrophysics Data System (ADS)

Kazemi, Alex A.; Ishihara, Abe

2014-09-01

In normal fiber, the refractive indices of the core and cladding do not change along the length of the fiber; however, by inducing a periodic modulation of refractive index along the length in the core of the optical fiber, the optical fiber grating is produced. This exhibits very interesting spectral properties and for this reason we propose to develop and integrate a distributed sensor network based on long period fiber gratings (LPFGs) technology which has grating periods on the order of 100 μm to 1 mm to be embedded in the wing section of aircraft to measure bending and torsion in real-time in order to measure wing deformation of commercial airplanes resulting in extensive benefits such as reduced structural weight, mitigation of induced drag and lower fuel consumption which is fifty percent of total cost of operation for airline industry. Fiber optic sensors measurement capabilities are as vital as they are for other sensing technologies, but optical measurements differ in important ways. In this paper we focus on the testing and aviation requirements for LPFG sensors. We discuss the bases of aviation standards for fiber optic sensor measurements, and the quantities that are measured. Our main objective is to optimize the design for material, mechanical, optical and environmental requirements. We discuss the analysis and evaluation of extensive testing of LPFG sensor systems such as attenuation, environmental, humidity, fluid immersion, temperature cycling, aging, smoke, flammability, impact resistance, flexure endurance, tensile, vitiation and shock.

Optical fiber spectroscopy: A study of the luminescent properties of the europium ion for thermal sensors

NASA Technical Reports Server (NTRS)

Buoncristiani, A. Martin

1992-01-01

Recently, there has been interest in developing a distributed temperature sensor integrated into an optical fiber. Such a system would allow embedding of the optical fiber within or on a structural material to provide for continuous monitoring of the material's temperature. Work has already begun on the development of a temperature sensor using the temperature dependent emission spectra from the lanthanide rare earths doped into crystalline hosts. The lifetime, the linewidth and the integrated intensity of this emission are each sensitive to changes in the temperature and can provide a basis for thermometry. One concept for incorporating this phenomena into an optical fiber based sensor involves bonding the optically active material to the cladding of an optical fiber and allowing the luminescent light to couple into the the fiber by the evanescent wave. Experimental work developing this concept has already been reported. Measurements of the linewidth of Eu3+:Y2O3, diffused into a fiber, made by Albin clearly show a strong and regular dependence on temperature over the range of 300 to 1000 K. We report here on a study of the temperature dependence of the lineshape of the emission at 611 nm using the data in references. We focus attention on understanding the general behavior of the Eu3+:Y2O3 system. Building upon understanding of this system we will be able to establish the physical criterial for a good optical fiber based temperature sensor and then to examine available data on other lanthanide rare earths and transition metal ions to determine the best luminescent system for temperature sensing in an optical fiber.

Fiber-Optic Sensors for Measurements of Torsion, Twist and Rotation: A Review.

PubMed

Budinski, Vedran; Donlagic, Denis

2017-02-23

Optical measurement of mechanical parameters is gaining significant commercial interest in different industry sectors. Torsion, twist and rotation are among the very frequently measured mechanical parameters. Recently, twist/torsion/rotation sensors have become a topic of intense fiber-optic sensor research. Various sensing concepts have been reported. Many of those have different properties and performances, and many of them still need to be proven in out-of-the laboratory use. This paper provides an overview of basic approaches and a review of current state-of-the-art in fiber optic sensors for measurements of torsion, twist and/or rotation.Invited Paper.

Fiber-Optic Sensors for Measurements of Torsion, Twist and Rotation: A Review †

PubMed Central

Budinski, Vedran; Donlagic, Denis

2017-01-01

Optical measurement of mechanical parameters is gaining significant commercial interest in different industry sectors. Torsion, twist and rotation are among the very frequently measured mechanical parameters. Recently, twist/torsion/rotation sensors have become a topic of intense fiber-optic sensor research. Various sensing concepts have been reported. Many of those have different properties and performances, and many of them still need to be proven in out-of-the laboratory use. This paper provides an overview of basic approaches and a review of current state-of-the-art in fiber optic sensors for measurements of torsion, twist and/or rotation. PMID:28241510

A Piezoelectroluminescent Fiber-Optical Sensor for Diagnostics of the 3D Stress State in Composite Structures

NASA Astrophysics Data System (ADS)

Pan'kov, A. A.

2018-05-01

The mathematical model of a piezoelectroluminescent fiber-optical sensor is developed for diagnostics of the 3D stress state of composite structures. The sensor model is a coaxial sector-compound layered cylinder consisting of a central optical fiber with electroluminescent and piezoelectric layers and an external uniform elastic buffer layer. The electroluminescent and piezoelectric layers are separated by radial-longitudinal boundaries, common for both layers, into geometrically equal six "measuring elements" — cylindrical two-layered sectors. The directions of 3D polarization of the piezoelectric phases and the frequencies of luminous efficacy of the electroluminescent phases are different in each sector. In the sensor, a thin translucent "internal" controlling electrode is located between the optical fiber and the electroluminescent layer, and the piezoelectric layer is coated by a thin "external" controlling electrode. The results of numerical modeling of the nonuniform coupled electroelastic fields of the piezoelectroluminescent fiber-optical sensor in the loaded "representative volume" of a composite, taking into account the action of the controlling voltage on the internal and external electrodes, of a numerical calculation of "informative and controlling coefficients" of the sensor, and of testing of an arbitrary 3D stress of state of a unidirectional glass-fiber plastic by the finite-element method are presented.

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

NASA Technical Reports Server (NTRS)

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

2007-01-01

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.

High Speed and High Spatial Density Parameter Measurement Using Fiber Optic Sensing Technology

NASA Technical Reports Server (NTRS)

Richards, William Lance (Inventor); Piazza, Anthony (Inventor); Parker, Allen R. Jr. (Inventor); Hamory, Philip J (Inventor); Chan, Hon Man (Inventor)

2017-01-01

The present invention is an improved fiber optic sensing system (FOSS) having the ability to provide both high spatial resolution and high frequency strain measurements. The inventive hybrid FOSS fiber combines sensors from high acquisition speed and low spatial resolution Wavelength-Division Multiplexing (WDM) systems and from low acquisition speed and high spatial resolution Optical Frequency Domain Reflection (OFDR) systems. Two unique light sources utilizing different wavelengths are coupled with the hybrid FOSS fiber to generate reflected data from both the WDM sensors and OFDR sensors operating on a single fiber optic cable without incurring interference from one another. The two data sets are then de-multiplexed for analysis, optionally with conventionally-available WDM and OFDR system analyzers.

FIBER AND INTEGRATED OPTICS: Multiplexed optical-fiber sensors with autodyne detection

NASA Astrophysics Data System (ADS)

Potapov, V. T.; Mamedov, A. M.; Shatalin, S. V.; Yushkaĭtis, R. V.

1993-09-01

A method is proposed for multiplexing optical-fiber interference sensors. The method involves autodyne reception of frequency-modulated radiation reflected back to the laser. The response of a He-Ne laser with a linearly varying generation frequency to radiation reflected back from a single-mode fiber is studied. The spectrum of beats caused in the laser radiation by the reflection is shown to be governed by the distribution of reflectors along the fiber. The phases of the spectral components contain information about the phase shift of the reflected optical signal. A hydrophone array with a sensitivity of 30 μrad/Hz1/2 is described. A distributed temperature sensor with a spatial resolution of 1 m is also described.

Silicon-Etalon Fiber-Optic Temperature Sensor

NASA Technical Reports Server (NTRS)

Beheim, Glenn; Fritsch, Klaus; Flatico, Joseph M.; Azar, Massood Tabib

1993-01-01

Developmental temperature sensor consists of silicon Fabry-Perot etalon attached to end of optical fiber. Features immunity to electrical interference, small size, light weight, safety, and chemical inertness. Output encoded in ration of intensities at two different wavelengths, rather than in overall intensity, with result that temperature readings not degraded much by changes in transmittance of fiber-optic link.

Fiber optic sensor for measurement of pressure fluctuations at high temperatures

NASA Technical Reports Server (NTRS)

Zuckerwar, Allan J.; Cuomo, Frank W.

1989-01-01

A fiber-optic sensor, based on the principle of the fiber-optic lever, is described which features small size, extended bandwidth, and capability to operate at high temeratures, as required for measurements in hypersonic flow. The principle of operation, design features peculiar to the intended application, and expected performance at high temperatures are described.

Distributed Fiber Optic Sensors for Earthquake Detection and Early Warning

NASA Astrophysics Data System (ADS)

Karrenbach, M. H.; Cole, S.

2016-12-01

Fiber optic cables placed along pipelines, roads or other infrastructure provide dense sampling of passing seismic wavefields. Laser interrogation units illuminate the fiber over its entire length, and strain at desired points along the fiber can be determined from the reflected signal. Single-mode optical fibers up to 50 km in length can provide a distributed acoustic sensing system (DAS) where the acoustic bandwidth of each channel is limited only by the round-trip time over the length of the cable (0.0005 s for a 50 km cable). Using a 10 m spatial resolution results in 4000 channels sampled at 2.5 kHz spanning a 40 km-long fiber deployed along a pipeline. The inline strain field is averaged along the fiber over a 10 m section of the cable at each desired spatial sample, creating a virtual sensor location. Typically, a dynamic strain sensitivity of sub-nanometers within each gauge along the entire length of the fiber can be achieved. This sensitivity corresponds to a particle displacement figure of approximately -90 dB ms-2Hz-½. Such a fiber optic sensor is not as sensitive as long-period seismometers used in earthquake networks, but given the large number of channels, small to medium-sized earthquakes can be detected, depending on distance from the array, and can be located with precision through arrival time inversions. We show several examples of earthquake recordings using distributed fiber optic arrays that were deployed originally for other purposes. A 480 km long section of a pipeline in Turkey was actively monitored with a DAS fiber optic system for activities in the immediate vicinity of the pipeline. The densely spaced sensor array along the pipeline detected earthquakes of 3.6 - 7.2 magnitude range, centered near Van, Turkey. Secondly, a fiber optic system located along a rail line near the Salton Sea in California was used to create a smaller scale fiber optic sensor array, on which earthquakes with magnitudes 2.2 - 2.7 were recorded from epicenters up to 65 km away. Our analysis shows that existing fiber optic installations along infrastructure could be combined to form a large aperture array with tens of thousands of channels for epicenter estimation and for early warning purposes, augmenting existing earthquake sensor networks.

Optical fiber sensors: Systems and applications. Volume 2

NASA Astrophysics Data System (ADS)

Culshaw, Brian; Dakin, John

State-of-the-art fiber-optic (FO) sensors and their applications are described in chapters contributed by leading experts. Consideration is given to interferometers, FO gyros, intensity- and wavelength-based sensors and optical actuators, Si in FO sensors, point-sensor multiplexing principles, and distributed FO sensor systems. Also examined are chemical, biochemical, and medical sensors; physical and chemical sensors for process control; FO-sensor applications in the marine and aerospace industries; FO-sensor monitoring systems for security and safety, structural integrity, NDE, and the electric-power industry; and the market situation for FO-sensor technology. Diagrams, drawings, graphs, and photographs are provided.

Fiber-optic security monitoring sensor

NASA Astrophysics Data System (ADS)

Englund, Marja; Ipatti, Ari; Karioja, Pentti

1997-09-01

In security monitoring, fiber-optic sensors are advantageous because strong and rugged optical fibers are thin, light, flexible and immune to electromagnetic interference. Optical fibers packaged into cables, such as, building and underground cables, can be used to detect even slightest disturbances, movements, vibrations, pressure changes and impacts along their entire length. When running an optical cable around a structure, and when using speckle pattern recognition technique for alarm monitoring, the distributed monitoring of the structure is possible. The sensing cable can be strung along fences, buried underground, embedded into concrete, mounted on walls, floors and ceilings, or wrapped around the specific components. In this paper, a fiber-optic security monitoring sensor based on speckle pattern monitoring is described. The description of the measuring method and the results of the experimental fiber installations are given. The applicability of embedded and surface mounted fibers to monitor the pressure and impact induced vibrations of fences and concrete structures as well as the loosening of critical parts in a power plant machinery were demonstrated in field and laboratory conditions. The experiences related to the applications and optical cable types are also discussed.

Fiber optic security monitoring sensor

NASA Astrophysics Data System (ADS)

Englund, Marja; Ipatti, Ari; Karioja, Pentti

1997-09-01

In security monitoring, fiber-optic sensors are advantageous because strong and rugged optical fibers are thin, light, flexible and immune to electromagnetic interference. Optical fibers packaged into cables, such as, building and underground cables, can be used to detect even slightest disturbances, movements, vibrations, pressure changes and impacts along their entire length. When running an optical cable around a structure, and when using speckle pattern recognition technique for alarm monitoring, the distributed monitoring of the structure is possible. The sensing cable can be strung along fences, buried underground, embedded into concrete, mounted on walls, floors and ceilings, or wrapped around the specific components. In this paper, a fiber-optic security monitoring sensor based on speckle pattern monitoring is described. The description of the measuring method and the results of the experimental fiber installations are given. The applicability of embedded and surface mounted fibers to monitor the pressure and impact induced vibrations of fences and concrete structures as well as the loosening of critical parts in a power plant machinery were demonstrated in field and laboratory conditions. The experiences related to the applications and optical cable types are also discussed.

Elastomeric optical fiber sensors and method for detecting and measuring events occurring in elastic materials

DOEpatents

Muhs, Jeffrey D.; Capps, Gary J.; Smith, David B.; White, Clifford P.

1994-01-01

Fiber optic sensing means for the detection and measurement of events such as dynamic loadings imposed upon elastic materials including cementitious materials, elastomers, and animal body components and/or the attrition of such elastic materials are provided. One or more optical fibers each having a deformable core and cladding formed of an elastomeric material such as silicone rubber are embedded in the elastic material. Changes in light transmission through any of the optical fibers due the deformation of the optical fiber by the application of dynamic loads such as compression, tension, or bending loadings imposed on the elastic material or by the attrition of the elastic material such as by cracking, deterioration, aggregate break-up, and muscle, tendon, or organ atrophy provide a measurement of the dynamic loadings and attrition. The fiber optic sensors can be embedded in elastomers subject to dynamic loadings and attrition such as commonly used automobiles and in shoes for determining the amount and frequency of the dynamic loadings and the extent of attrition. The fiber optic sensors are also useable in cementitious material for determining the maturation thereof.

Ultra Small Integrated Optical Fiber Sensing System

PubMed Central

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

2012-01-01

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 μm, 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.

Mesh-type acoustic vector sensor

NASA Astrophysics Data System (ADS)

Zalalutdinov, M. K.; Photiadis, D. M.; Szymczak, W. G.; McMahon, J. W.; Bucaro, J. A.; Houston, B. H.

2017-07-01

Motivated by the predictions of a theoretical model developed to describe the acoustic flow force exerted on closely spaced nano-fibers in a viscous medium, we have demonstrated a novel concept for a particle velocity-based directional acoustic sensor. The central element of the concept exploits the acoustically induced normal displacement of a fine mesh as a measure of the collinear projection of the particle velocity in the sound wave. The key observations are (i) the acoustically induced flow force on an individual fiber within the mesh is nearly independent of the fiber diameter and (ii) the mesh-flow interaction can be well-described theoretically by a nearest neighbor coupling approximation. Scaling arguments based on these two observations indicate that the refinement of the mesh down to the nanoscale leads to significant improvements in performance. The combination of the two dimensional nature of the mesh together with the nanoscale dimensions provides a dramatic gain in the total length of fiber exposed to the flow, leading to a sensitivity enhancement by orders of magnitude. We describe the fabrication of a prototype mesh sensor equipped with optical readout. Preliminary measurements carried out over a considerable bandwidth together with the results of numerical simulations are in good agreement with the theory, thus providing a proof of concept.

Fiber optical sensing on-board communication satellites

NASA Astrophysics Data System (ADS)

Hurni, A.; Lemke, N. M. K.; Roner, M.; Obermaier, J.; Putzer, P.; Kuhenuri Chami, N.

2017-11-01

Striving constantly to reduce mass, AIT effort and overall cost of the classical point-to-point wired temperature sensor harness on-board telecommunication satellites, OHB System (formerly Kayser-Threde) has introduced the Hybrid Sensor Bus (HSB) system. As a future spacecraft platform element, HSB relies on electrical remote sensor units as well as fiber-optical sensors, both of which can serially be connected in a bus architecture. HSB is a modular measurement system with many applications, also thanks to the opportunities posed by the digital I²C bus. The emphasis, however, is on the introduction of fiber optics and especially fiber-Bragg grating (FBG) temperature sensors as disruptive innovation for the company's satellite platforms. The light weight FBG sensors are directly inscribed in mechanically robust and radiation tolerant fibers, reducing the need for optical fiber connectors and splices to a minimum. Wherever an FBG sensor shall be used, the fiber is glued together with a corresponding temperature transducer to the satellites structure or to a subsystem. The transducer is necessary to provide decoupling of mechanical stress, but simultaneously ensure a high thermal conductivity. HSB has been developed in the frame of an ESA-ARTES program with European and German co-funding and will be verified as flight demonstrator on-board the German Heinrich Hertz satellite (H2Sat). In this paper the Engineering Model development of HSB is presented and a Fiber-optical Sensor Multiplexer for a more flexible sensor bus architecture is introduced. The HSB system aims at telecommunication satellite platforms with an operational life time beyond 15 years in geostationary orbit. It claims a high compatibility in terms of performance and interfaces with existing platforms while it was designed with future applications with increased radiation exposure already in mind. In its basic configuration HSB consists of four modules which are the Power Supply Unit, the HSB Controller Module, the Interrogator Controller Module and the Analog Front-End for the fiber-optical interrogation. The Interrogator Controller Module handles both, the electrical and fiber-optical sensor network. For the latter it is to be completed by the Analog Front-End. On this front-end, a tunable laser diode is implemented for the scanning of the FBG sensors. The reflected spectra are measured on multiple fiber channels and are then evaluated by use of a peak detection algorithm in order to obtain a precise temperature measurement. The precise operation of the photonic system on long terms can be guaranteed thanks to an inorbit calibration concept.

Instrumentation and data acquisition for satellite testing in nuclear environments

NASA Astrophysics Data System (ADS)

Samyal, B.; Naumann, W.

1982-06-01

Electro-optic and magnetic-optic sensors for measurement of SGEMP-induced electromagnetic fields in and around a satellite in a UGT environment and a fiber optic data link suitable for relaying analog measurements inside the satellite to outside data collection devices are described. The electro-optic and magneto-optic sensors are based on the Pockels and Faraday Effects, respectively. The former has a sensitivity range of 10 to the second power - 10 to the 6th power v/m and the latter 1 x 10 to the minus 6th power - 34 x 10 to the minus 4th power Weber/meters square. Brief theoretical reviews and optical systems for the application of these sensors are presented. These sensors have several advantages over the conventional electrical sensors and they exhibit a great potential for measurement of electromagenetic fields. However, the effects of radiation on these sensors are uncertain and need to be assessed for any future development of these sensors. The fiber optic data link consists of several transmitter modules, located at the satellite, connected by optical fibers to the corresponding receiver modules located at a radiation safe alcove.

Piezoelectroluminescent Optical Fiber Sensor for Diagnostics of the Stress State and Defectoscopy of Composites

NASA Astrophysics Data System (ADS)

Pan'kov, A. A.

2017-05-01

A mathematical model is developed for a piezoelectroluminescent optical fiber pressure sensor is developed in which the mechanoluminescence effect results from the interaction of electroluminescent and piezoelectric coverings put on an optical fiber. The additional control electrodes expand the possibilities of analyzing the distribution of pressure along the fiber. The probability density function of pressure distribution along the sensor is found from results of the measured intensity of light coming from the optical fiber. The problem is reduced to the solution of the Fredholm integral equation of the first kind with a difference kernel depending on the effective parameters of the sensor and properties of an electroluminophor. An algorithm of step-by-step scanning of the nonuniform pressure along the sensor by using the running wave of control voltage is developed. On each step, the amplitude of the wave is increased by a small value, which leads to the appearance of additional luminescence sections of the electroluminophor and the corresponding "glow pulses" at the output of the optical fiber sensor. The sought-for nodal values of pressure and their locations are calculated according to the form of the glow pulses with account of amplitude of the wave at each scanning step. Results of numerical modeling of the process of location of pressure nonuniformities along the sensor by the running wave are found for different scanning steps.

A packaged, low-cost, robust optical fiber strain sensor based on small cladding fiber sandwiched within periodic polymer grating.

PubMed

Chiang, Chia-Chin; Li, Chein-Hsing

2014-06-02

In the present study, a novel packaged long-period fiber grating (PLPFG) strain sensor is first presented. The MEMS process was utilized to fabricate the packaged optical fiber strain sensor. The sensor structure consisted of etched optical fiber sandwiched between two layers of thick photoresist SU-8 3050 and then packaged with poly (dimethylsiloxane) (PDMS) polymer material to construct the PLPFG strain sensor. The PDMS packaging material was used to prevent the glue effect, wherein glue flows into the LPFG structure and reduces coupling strength, in the surface bonding process. Because the fiber grating was packaged with PDMS material, it was effectively protected and made robust. The resonance attenuation dip of PLPFG grows when it is loading. This study explored the size effect of the grating period and fiber diameter of PLPFG via tensile testing. The experimental results found that the best strain sensitivity of the PLPFG strain sensor was -0.0342 dB/με, and that an R2 value of 0.963 was reached.

Optical fiber sensors measurement system and special fibers improvement

NASA Astrophysics Data System (ADS)

Jelinek, Michal; Hrabina, Jan; Hola, Miroslava; Hucl, Vaclav; Cizek, Martin; Rerucha, Simon; Lazar, Josef; Mikel, Bretislav

2017-06-01

We present method for the improvement of the measurement accuracy in the optical frequency spectra measurements based on tunable optical filters. The optical filter was used during the design and realization of the measurement system for the inspection of the fiber Bragg gratings. The system incorporates a reference block for the compensation of environmental influences, an interferometric verification subsystem and a PC - based control software implemented in LabView. The preliminary experimental verification of the measurement principle and the measurement system functionality were carried out on a testing rig with a specially prepared concrete console in the UJV Řež. The presented system is the laboratory version of the special nuclear power plant containment shape deformation measurement system which was installed in the power plant Temelin during last year. On the base of this research we started with preparation other optical fiber sensors to nuclear power plants measurement. These sensors will be based on the microstructured and polarization maintaining optical fibers. We started with development of new methods and techniques of the splicing and shaping optical fibers. We are able to made optical tapers from ultra-short called adiabatic with length around 400 um up to long tapers with length up to 6 millimeters. We developed new techniques of splicing standard Single Mode (SM) and Multimode (MM) optical fibers and splicing of optical fibers with different diameters in the wavelength range from 532 to 1550 nm. Together with development these techniques we prepared other techniques to splicing and shaping special optical fibers like as Polarization-Maintaining (PM) or hollow core Photonic Crystal Fiber (PCF) and theirs cross splicing methods with focus to minimalize backreflection and attenuation. The splicing special optical fibers especially PCF fibers with standard telecommunication and other SM fibers can be done by our developed techniques. Adjustment of the splicing process has to be prepared for any new optical fibers and new fibers combinations. The splicing of the same types of fibers from different manufacturers can be adjusted by several tested changes in the splicing process. We are able to splice PCF with standard telecommunication fiber with attenuation up to 2 dB. The method is also presented. Development of these new techniques and methods of the optical fibers splicing are made with respect to using these fibers to another research and development in the field of optical fibers sensors, laser frequency stabilization and laser interferometry based on optical fibers. Especially for the field of laser frequency stabilization we developed and present new techniques to closing microstructured fibers with gases inside.

Long-distance fiber Bragg grating sensor system with a high optical signal-to-noise ratio based on a tunable fiber ring laser configuration.

PubMed

Rao, Yun-Jiang; Ran, Zeng-Ling; Chen, Rong-Rui

2006-09-15

A novel tunable fiber ring laser configuration with a combination of bidirectional Raman amplification and dual erbium-doped fiber (EDF) amplification is proposed for realizing high optical signal-to-noise ratio (SNR), long-distance, quasi-distributed fiber Bragg grating (FBG) sensing systems with large capacities and low cost. The hybrid Raman-EDF amplification configuration arranged in the ring laser can enhance the optical SNR of FBG sensor signals significantly owing to the good combination of the high gain of the erbium-doped fiber amplifier (EDFA) and the low noise of the Raman amplification. Such a sensing system can support a large number of FBG sensors because of the use of a tunable fiber Fabry-Perot filter located within the ring laser and spatial division multiplexing for expansion of sensor channels. Experimental results show that an excellent optical SNR of approximately 60 dB has been achieved for a 50 km transmission distance with a low Raman pump power of approximately 170 mW at a wavelength of 1455 nm and a low EDFA pump power of approximately 40 mW at a wavelength of 980 nm, which is the highest optical SNR achieved so far for a 50 km long FBG sensor system, to our knowledge.

A Mechanical Switch Using Spectral Microshifts

NASA Astrophysics Data System (ADS)

Mitchell, Gordon L.; Saaski, Elric W.; Hartl, James C.

1989-02-01

Among the simplest fiber optic sensors, are those which operate in a binary fashion; they were the first sensor types to be developed. Early experiments with fiber bundles and shutters produced demonstrations of, for example, displacement sensors. Typical applications range from position sensing for aircraft landing gear to counting objects on a production line. Because they frequently replace electrical snap action switches, binary sensors are generally called optical switches. Optical switch applications account for a much larger market than the more complex analog measurements discussed in the balance of this volume. This paper presents an optical switch concept that uses a single fiber and is tolerant of back reflections. The sensor element is a low finesse Fabry-Perot pressure sensor which replaces the electrical contact in a conventional snap action switch.

Fiber-linked interferometric pressure sensor

NASA Technical Reports Server (NTRS)

Beheim, G.; Fritsch, K.; Poorman, R. N.

1987-01-01

A fiber-optic pressure sensor is described which uses a diaphragm to modulate the mirror separation of a Fabry-Perot cavity (the sensing cavity). A multimode optical fiber delivers broadband light to the sensing cavity and returns the spectrally modulated light which the cavity reflects. The sensor's output spectrum is analyzed using a tunable Fabry-Perot cavity (the reference cavity) to determine the mismatch in the mirror separations of the two cavities. An electronic servo control uses this result to cause the mirror separation of the reference cavity to equal that of the sensing cavity. The displacement of the pressure-sensing diaphragm is then obtained by measuring the capacitance of the reference cavity's metal-coated mirrors. Relative to other fiber-optic sensors, an important advantage of this instrument is its high immunity to the effects of variations in both the transmissivity of the fiber link and the wavelength of the optical source.

Seismic fiber optic multiplexed sensors for exploration and reservoir management

NASA Astrophysics Data System (ADS)

Houston, Mark H.

2000-12-01

Reliable downhole communications, control and sensor networks will dramatically improve oil reservoir management practices and will enable the construction of intelligent or smart-well completions. Fiber optic technology will play a key role in the implementation of these communication, control and sensing systems because of inherent advantages of power, weight and reliability over more conventional electronic-based systems. Field test data, acquired using an array of fiber optic seismic hydrophones within a steam-flood, heavy oil- production filed, showed a significant improvement (10X in this specific case) in subsurface resolution as compared to conventional surface seismic acquisition. These results demonstrate the viability of using multiplexed fiber optic sensors for exploration and reservoir management in 3D vertical seismic profiling (VSP) surveys and in permanent sensor arrays for 4D surveys.

Structural health monitoring using smart optical fiber sensors

NASA Astrophysics Data System (ADS)

Davies, Heddwyn; Everall, Lorna A.; Gallon, Andrew M.

2001-04-01

This paper describes the potential of a smart monitoring system, incorporating optical fiber sensing techniques, to provide important structural information to designers and users alike. This technology has application in all areas including aerospace, civil, maritime and automotive engineering. In order to demonstrate the capability of the sensing system it has been installed in a 35 m free-standing carbon fiber yacht mast, where a complete optical network of strain and temperature sensors were embedded into a composite mast and boom during lay-up. The system was able to monitor the behavior of the composite rig through a range of handling conditions and the resulting strain information could be used by engineers to improve the structural design process. The optical strain sensor system comprises of three main components: the sensor network, the opto-electronic data acquisition unit (OFSSS) and the external PC which acts as a data log and display. Embedded fiber optic sensors have wide ranging application for structural load monitoring. Due to their small size, optical fiber sensors can be readily embedded into composite materials. Other advantages include their immediate multiplexing capability and immunity to electromagnetic interference. The capability of this system has been demonstrated within the maritime environment, but can be adapted for any application.

Elasto-plastic bond mechanics of embedded fiber optic sensors in concrete under uniaxial tension with strain localization

NASA Astrophysics Data System (ADS)

Li, Qingbin; Li, Guang; Wang, Guanglun

2003-12-01

Brittleness of the glass core inside fiber optic sensors limits their practical usage, and therefore they are coated with low-modulus softer protective materials. Protective coatings absorb a portion of the strain, and hence part of the structural strain is sensed. The study reported here corrects for this error through development of a theoretical model to account for the loss of strain in the protective coating of optical fibers. The model considers the coating as an elasto-plastic material and formulates strain transfer coefficients for elastic, elasto-plastic and strain localization phases of coating deformations in strain localization in concrete. The theoretical findings were verified through laboratory experimentation. The experimental program involved fabrication of interferometric optical fiber sensors, embedding within mortar samples and tensile tests in a closed-loop servo-hydraulic testing machine. The elasto-plastic strain transfer coefficients were employed for correction of optical fiber sensor data and results were compared with those of conventional extensometers.

Isolation of Thermal and Strain Responses in Composites Using Embedded Fiber Bragg Grating Temperature Sensors

DTIC Science & Technology

2013-05-10

13. SUPPLEMENTARY NOTES 14. ABSTRACT In this research, fiber Bragg grating ( FBG ) optical temperature sensors are used for structural health...surface of a composite structure. FBG sensors also respond to axial strain in the optical fiber, thus any structural strain experienced by the composite...features. First, a three-dimensional array of FBG temperature sensors has been embedded in a carbon/epoxy composite structure, consisting of both in

Optical fiber sensors: Accelerating applications in Navy ships

NASA Astrophysics Data System (ADS)

Day, G. W.; Lovely, P. S.; Whitesel, H. K.; Hickernell, R. K.

1994-05-01

The Navy needs new sensors for shipboard machinery monitoring and control, condition-based maintenance, and damage assessment. Optical fiber sensors are strongly preferred because of their immunity to electrical disturbances, as well as potential size, weight, and performance advantages. But despite well over a decade of development and promise, relatively few optical fiber sensors available today can meet the Navy's needs with acceptable performance and cost. This report examines the reasons and recommends strategies to help the Navy achieve its goals. Some of the recommendations confirm approaches that the Navy is already implementing. Optical fiber sensors have very valuable potential advantages, but those that the Navy can use may remain too expensive to be deployed if the Navy uses traditional methods of writing specifications and soliciting development and procurement bids. For this reason, the study focuses on cooperation with industry and promoting commercial off-the-shelf and dual-use technology.

Application of Fiber Optic Instrumentation

NASA Technical Reports Server (NTRS)

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

2012-01-01

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.

Active polymer materials for optical fiber CO2 sensors

NASA Astrophysics Data System (ADS)

Wysokiński, Karol; Filipowicz, Marta; Stańczyk, Tomasz; Lipiński, Stanisław; Napierała, Marek; Murawski, Michał; Nasiłowski, Tomasz

2017-04-01

CO2 optical fiber sensors based on polymer active materials are presented in this paper. Ethyl cellulose was proven to be a good candidate for a matrix material of the sensor, since it gives porous, thick and very sensitive layers. Low-cost sensors based on polymer optical fibers have been elaborated. Sensors have been examined for their sensitivity to CO2, temperature and humidity. Response time during cyclic exposures to CO2 have been also determined. Special layers exhibiting irreversible change of color during exposure to carbon dioxide have been developed. They have been verified for a possible use in smart food packaging.

Development of a fiber optic high temperature strain sensor

NASA Technical Reports Server (NTRS)

Rausch, E. O.; Murphy, K. E.; Brookshire, S. P.

1992-01-01

From 1 Apr. 1991 to 31 Aug. 1992, the Georgia Tech Research Institute conducted a research program to develop a high temperature fiber optic strain sensor as part of a measurement program for the space shuttle booster rocket motor. The major objectives of this program were divided into four tasks. Under Task 1, the literature on high-temperature fiber optic strain sensors was reviewed. Task 2 addressed the design and fabrication of the strain sensor. Tests and calibration were conducted under Task 3, and Task 4 was to generate recommendations for a follow-on study of a distributed strain sensor. Task 4 was submitted to NASA as a separate proposal.

Harsh-environment fiber optic sensors for structural monitoring applications

NASA Astrophysics Data System (ADS)

Fielder, Robert S.; Stinson-Bagby, Kelly L.; Palmer, Matthew E.

2004-07-01

The objective of the work presented was to develop a suite of sensors for use in high-temperature aerospace environments, including turbine engine monitoring, hypersonic vehicle skin friction measurements, and support ground and flight test operations. A fiber optic sensor platform was used to construct the sensor suite. Successful laboratory demonstrations include calibration of a pressure sensor to 100psi at a gas temperature of 800°C, calibration of an accelerometer to 2.5g at a substrate temperature of 850°C. Temperature sensors have been field tested up to 1400°C, and a skin friction sensor designed for 870°C operation has been constructed. The key advancement that enabled the operation of these novel harsh environment sensors was a fiber optic packaging methodology that allowed the coupling of alumina and sapphire transducer components, optical fiber, and high-temperature alloy housing materials. The basic operation of the sensors and early experimental results are presented. Each of the sensors described here represent a quantifiable advancement in the state of the art in high-temperature physical sensors and will have a significant impact on the aerospace propulsion instrumentation industry.

Detection of bacteria using bacteriophage with hollow gold nanostructures immobilized fiber optic sensor

NASA Astrophysics Data System (ADS)

Halkare, Pallavi; Punjabi, Nirmal; Wangchuk, Jigme; Kondabagil, Kiran; Mukherji, Soumyo

2016-04-01

Hollow gold nanostructures (HGNS) have been used in variety of optical biosensors due to their inherent advantage of operating at near infra red (NIR) wavelength, large extinction coefficient and high dielectric sensitivity. The absorption wavelength of these nanostructures can be modulated by changing the ratio of hollow region to the core shell thickness. The aim of the present study is to incorporate the properties of HGNS, to develop LSPR based U-bent fiber optic sensor for detection of pathogens. The detection was carried out using an experimental set up consisting of a white light source, 200 μm diameter optical fiber having bend diameter of 1.6 mm +/- 0. 2 mm and a spectrometer. The HGNS were immobilized on the decladded portion of the fiber optic probe by chemisorptions. The effective plasmon penetration depth of the HGNS immobilized fiber optic sensor was approximated by using alternating layers of positively and negatively charged polyelectrolytes. The HGNS immobilized U-bent fiber optic sensor was used for detection of E.coli B40 strain using bacteriophage T4. The preliminary experiments were carried out with 104 cfu/ml of E.coli B40 and the change in absorbance obtained was approx. 0.042 +/- 0.0045 abs. units (n = 3). The response of this sensor was found to be better than spherical gold nanoparticle immobilized sensing platforms.

A flexible tactile sensitive sheet using a hetero-core fiber optic sensor

NASA Astrophysics Data System (ADS)

Fujino, S.; Yamazaki, H.; Hosoki, A.; Watanabe, K.

2014-05-01

In this report, we have designed a tactile sensitive sheet based on a hetero-core fiber-optic sensor, which realize an areal sensing by using single sensor potion in one optical fiber line. Recently, flexible and wide-area tactile sensing technology is expected to applied to acquired biological information in living space and robot achieve long-term care services such as welfare and nursing-care and humanoid technology. A hetero-core fiber-optic sensor has several advantages such as thin and flexible transmission line, immunity to EMI. Additionally this sensor is sensitive to moderate bending actions with optical loss changes and is independent of temperature fluctuation. Thus, the hetero-core fiber-optic sensor can be suitable for areal tactile sensing. We measure pressure characteristic of the proposed sensitive sheet by changing the pressure position and pinching characteristic on the surface. The proposed tactile sensitive sheet shows monotonic responses on the whole sensitive sheet surface although different sensitivity by the position is observed at the sensitive sheet surface. Moreover, the tactile sensitive sheet could sufficiently detect the pinching motion. In addition, in order to realize the discrimination between pressure and pinch, we fabricated a doubled-over sensor using a set of tactile sensitive sheets, which has different kinds of silicon robbers as a sensitive sheet surface. In conclusion, the flexible material could be given to the tactile sensation which is attached under proposed sensitive sheet.

Fabrication Quality Analysis of a Fiber Optic Refractive Index Sensor Created by CO2 Laser Machining

PubMed Central

Chen, Chien-Hsing; Yeh, Bo-Kuan; Tang, Jaw-Luen; Wu, Wei-Te

2013-01-01

This study investigates the CO2 laser-stripped partial cladding of silica-based optic fibers with a core diameter of 400 μm, which enables them to sense the refractive index of the surrounding environment. However, inappropriate treatments during the machining process can generate a number of defects in the optic fiber sensors. Therefore, the quality of optic fiber sensors fabricated using CO2 laser machining must be analyzed. The results show that analysis of the fiber core size after machining can provide preliminary defect detection, and qualitative analysis of the optical transmission defects can be used to identify imperfections that are difficult to observe through size analysis. To more precisely and quantitatively detect fabrication defects, we included a tensile test and numerical aperture measurements in this study. After a series of quality inspections, we proposed improvements to the existing CO2 laser machining parameters, namely, a vertical scanning pathway, 4 W of power, and a feed rate of 9.45 cm/s. Using these improved parameters, we created optical fiber sensors with a core diameter of approximately 400 μm, no obvious optical transmission defects, a numerical aperture of 0.52 ± 0.019, a 0.886 Weibull modulus, and a 1.186 Weibull-shaped parameter. Finally, we used the optical fiber sensor fabricated using the improved parameters to measure the refractive indices of various solutions. The results show that a refractive-index resolution of 1.8 × 10−4 RIU (linear fitting R2 = 0.954) was achieved for sucrose solutions with refractive indices ranging between 1.333 and 1.383. We also adopted the particle plasmon resonance sensing scheme using the fabricated optical fibers. The results provided additional information, specifically, a superior sensor resolution of 5.73 × 10−5 RIU, and greater linearity at R2 = 0.999. PMID:23535636

Monolithic integrated optic fiber Bragg grating sensor interrogator

NASA Astrophysics Data System (ADS)

Mendoza, Edgar A.; Esterkin, Yan; Kempen, Cornelia; Sun, Songjian

2010-04-01

Fiber Bragg gratings (FBGs) are a mature sensing technology that has gained rapid acceptance in civil, aerospace, chemical and petrochemical, medicine, aviation and automotive industries. Fiber Bragg grating sensors can be use for a variety of measurements including strain, stress, vibration, acoustics, acceleration, pressure, temperature, moisture, and corrosion distributed at multiple locations within the structure using a single fiber element. The most prominent advantages of FBGs are: small size and light weight, multiple FBG transducers on a single fiber, and immunity to radio frequency interference. A major disadvantage of FBG technology is that conventional state-of-the-art fiber Bragg grating interrogation systems are typically bulky, heavy, and costly bench top instruments that are assembled from off-the-shelf fiber optic and optical components integrated with a signal electronics board into an instrument console. Based on the need for a compact FBG interrogation system, this paper describes recent progress towards the development of a miniature fiber Bragg grating sensor interrogator (FBG-TransceiverTM) system based on multi-channel monolithic integrated optic sensor microchip technology. The integrated optic microchip technology enables the monolithic integration of all of the functionalities, both passive and active, of conventional bench top FBG sensor interrogators systems, packaged in a miniaturized, low power operation, 2-cm x 5-cm small form factor (SFF) package suitable for the long-term structural health monitoring in applications where size, weight, and power are critical for operation.

Fiber-optic sensing in cryogenic environments. [for rocket propellant tank monitoring

NASA Technical Reports Server (NTRS)

Sharma, M.; Brooks, R. E.

1980-01-01

Passive optical sensors using fiber-optic signal transmission to a remote monitoring station are explored as an alternative to electrical sensors used to monitor the status of explosive propellants. The designs of passive optical sensors measuring liquid level, pressure, and temperature in cryogenic propellant tanks are discussed. Test results for an experimental system incorporating these sensors and operating in liquid nitrogen demonstrate the feasibility of passive sensor techniques and indicate that they can serve as non-hazardous replacements for more conventional measuring equipment in explosive environments.

Quasidistributed temperature sensor based on dense wavelength-division multiplexing optical fiber delay

NASA Astrophysics Data System (ADS)

Su, Jun; Yang, Ning; Fan, Zhiqiang; Qiu, Qi

2017-10-01

We report on a fiber-optic delay-based quasidistributed temperature sensor with high precision. The device works by detecting the delay induced by the temperature instead of the spectrum. To analyze the working principle of this sensor, the thermal dependence of the fiber-optic delay was theoretically investigated and the delay-temperature coefficient was measured to be 42.2 ps/km°C. In this sensor, quasidistributed measurement of temperature could be easily realized by dense wavelength-division multiplexing and wavelength addressing. We built and tested a prototype quasidistributed temperature sensor with eight testing points equally distributed along a 32.61-km-long fiber. The experimental results demonstrate an average error of <0.1°C. These results prove that this quasidistributed temperature sensor is feasible and that it is a viable option for simple and economic temperature measurements.

Development of SPR temperature sensor using Au/TiO2 on hetero-core optical fiber

NASA Astrophysics Data System (ADS)

Kitagawa, Sho; Yamazaki, Hiroshi; Hosoki, Ai; Nishiyama, Michiko; Watanabe, Kazuhiro

2016-03-01

This paper describes a novel temperature sensor based on a hetero-core structured fiber optic surface plasmon resonance (SPR) sensor with multi-layer thin film of gold (Au) and titanium dioxide (TiO2). Temperature condition is an essential parameter in chemical plants for avoiding fire accident and controlling qualities of chemical substances. Several fiber optic temperature sensors have been developed for some advantages such as immunity to electromagnetic interference, corrosion resistance and no electrical leakage. The proposed hetero-core fiber optic SPR sensor detects temperature condition by measuring slight refractive index changes of TiO2 which has a large thermo-optic coefficient. We experimentally confirmed that the SPR resonant wavelength in the hetero-core SPR sensor with coating an Au film which slightly depended on temperature changes in the range from 20 °C to 80 °C. In addition, it was experimentally shown that the proposed SPR temperature sensor with multi-layer film of Au and TiO2 had the SPR resonant wavelength shift of 1.6 nm due to temperature change from -10 °C to 50 °C. As a result, a series of experiments successfully demonstrated that the proposed sensor was able to detect temperature directly depending on the thermo-optic effect of TiO2.

Optical Sensors Based on Single Arm Thin Film Waveguide Interferometer

NASA Technical Reports Server (NTRS)

Sarkisov, Sergey S.

1997-01-01

All the goals of the research effort for the first year were met by the accomplishments. Additional efforts were done to speed up the process of development and construction of the experimental gas chamber which will be completed by the end of 1997. This chamber incorporates vacuum sealed multimode optical fiber lines which connect the sensor to the remote light source and signal processing equipment. This optical fiber line is a prototype of actual optical communication links connecting real sensors to a control unit within an aircraft or spacecraft. An important problem which we are planning to focus on during the second year is coupling of optical fiber line to the sensor. Currently this problem is solved using focusing optics and prism couplers. More reliable solutions are planned to be investigated.

Tension and compression measurements in composite utility poles using fiber optic grating sensors

NASA Astrophysics Data System (ADS)

Udd, Eric; Corona-Bittick, Kelli; Slattery, Kerry T.; Dorr, Donald J.

1995-04-01

Composite utility poles have the potential to overcome many of the limitations of wooden poles that are currently widely used. Significant advantages include superior strength and uniformity, light weight for ease of deployment, the ability to be recycled reducing hazardous waste associated with chemically treated wooden poles, and compatibility with embedded fiber optic sensors allowing structural loads to be monitored. This paper describes the usage of fiber optic grating sensors to support structural testing of a 22 foot composite pole.

Measurement of Temperature and Relative Humidity with Polymer Optical Fiber Sensors Based on the Induced Stress-Optic Effect.

PubMed

Leal-Junior, Arnaldo; Frizera-Neto, Anselmo; Marques, Carlos; Pontes, Maria José

2018-03-20

This paper presents a system capable of measuring temperature and relative humidity with polymer optical fiber (POF) sensors. The sensors are based on variations of the Young's and shear moduli of the POF with variations in temperature and relative humidity. The system comprises two POFs, each with a predefined torsion stress that resulted in a variation in the fiber refractive index due to the stress-optic effect. Because there is a correlation between stress and material properties, the variation in temperature and humidity causes a variation in the fiber's stress, which leads to variations in the fiber refractive index. Only two photodiodes comprise the sensor interrogation, resulting in a simple and low-cost system capable of measuring humidity in the range of 5-97% and temperature in the range of 21-46 °C. The root mean squared errors (RMSEs) between the proposed sensors and the reference were 1.12 °C and 1.36% for the measurements of temperature and relative humidity, respectively. In addition, fiber etching resulted in a sensor with a 2 s response time for a relative humidity variation of 10%, which is one of the lowest recorded response times for intrinsic POF humidity sensors.

Shape Sensing Using a Multi-Core Optical Fiber Having an Arbitrary Initial Shape in the Presence of Extrinsic Forces

NASA Technical Reports Server (NTRS)

Rogge, Matthew D. (Inventor); Moore, Jason P. (Inventor)

2014-01-01

Shape of a multi-core optical fiber is determined by positioning the fiber in an arbitrary initial shape and measuring strain over the fiber's length using strain sensors. A three-coordinate p-vector is defined for each core as a function of the distance of the corresponding cores from a center point of the fiber and a bending angle of the cores. The method includes calculating, via a controller, an applied strain value of the fiber using the p-vector and the measured strain for each core, and calculating strain due to bending as a function of the measured and the applied strain values. Additionally, an apparent local curvature vector is defined for each core as a function of the calculated strain due to bending. Curvature and bend direction are calculated using the apparent local curvature vector, and fiber shape is determined via the controller using the calculated curvature and bend direction.

Microshell-tipped optical fibers as sensors of high-pressure pulses in adverse environments

DOE Office of Scientific and Technical Information (OSTI.GOV)

Benjamin, R.F.; Mayer, F.J.; Maynard, R.L.

1984-01-01

We have developed and used an optical-fiber sensor for detecting the arrival of strong pressure pulses. The sensor consists of an optical fiber, tipped with a gas-filled microballoon. They have been used successfully in adverse environments including explosives, ballistics and electromagnetic pulses (EMP). The sensor produces a bright optical pulse caused by the rapid shock-heating of a gas, typically argon or xenon, which is confined in the spherical glass or plastic microballoon. The light pulse is transmitted via the optical fiber to a photo detector, usually a streak camera or photomultiplier tube. The microballoon optical sensor (called an optical pinmore » by analogy to standard electrical pins), was originally developed for diagnosing an explosive, pulsed-power generator. Optical pins are required due to the EMP. The optical pins are economical arrival-time indicators because many channels can be recorded by one streak camera. The generator tests and related experiments, involving projectile velocities and detonation velocities of several kilometers per/sec have demonstrated the usefulness of the sensors in explosives and ballistics applications. We have also measured the sensitivity of the optical pins to slowly-moving projectiles and found that a 200 m/sec projectile impacting the microballoon sensor produces a flash having a risetime less than 100 ns and a pulse duration (FWHM) of less than 300 ns. The technical and cost advantages of this optical pin make it potentially useful for many electromagnetic, explosive, and ballistics applications.« less

Temperature Measurement and Damage Detection in Concrete Beams Exposed to Fire Using PPP-BOTDA Based Fiber Optic Sensors.

PubMed

Bao, Yi; Hoehler, Matthew S; Smith, Christopher M; Bundy, Matthew; Chen, Genda

2017-10-01

In this study, distributed fiber optic sensors based on pulse pre-pump Brillouin optical time domain analysis (PPP-BODTA) are characterized and deployed to measure spatially-distributed temperatures in reinforced concrete specimens exposed to fire. Four beams were tested to failure in a natural gas fueled compartment fire, each instrumented with one fused silica, single-mode optical fiber as a distributed sensor and four thermocouples. Prior to concrete cracking, the distributed temperature was validated at locations of the thermocouples by a relative difference of less than 9 %. The cracks in concrete can be identified as sharp peaks in the temperature distribution since the cracks are locally filled with hot air. Concrete cracking did not affect the sensitivity of the distributed sensor but concrete spalling broke the optical fiber loop required for PPP-BOTDA measurements.

Design and research of sun sensor based on technology of optical fiber

NASA Astrophysics Data System (ADS)

Li, Ye; Zhou, Wang; Li, Dan

2010-08-01

A kind of sun sensor is designed based on the optical fiber. This project consists of three parts: optical head, photoelectric sensor and signal processing unit. The innovation of this design lies in the improvement of traditional sun sensor, where multi-fibers, used as a leader, are symmetrically distributed on the surface of a spacecraft. To determine the attitude of a spacecraft, the sun sensor should measure the direction of the sun. Because the fiber length can be adjusted according to the fact, photoelectric sensor can be placed deeply inside a spacecraft to protect the photoelectric sensor against the damage by the high-energy particles from outer space. The processing unit calculates the difference value of sun energy imported by each pair of opposite optical fiber so as to obtain the angle and the orientation between the spacecraft and the sun. This sun sensor can suit multi-field of view, both small and large. It improves the accuracy of small field of view and increases the precision of locating a spacecraft. This paper briefly introduces the design of processing unit. This sun sensor is applicable to detect the attitude of a spacecraft. In addition, it can also be used in solar tracking system of PV technology.

In-Situ Three-Dimensional Shape Rendering from Strain Values Obtained Through Optical Fiber Sensors

NASA Technical Reports Server (NTRS)

Chan, Hon Man (Inventor); Parker, Jr., Allen R. (Inventor)

2015-01-01

A method and system for rendering the shape of a multi-core optical fiber or multi-fiber bundle in three-dimensional space in real time based on measured fiber strain data. Three optical fiber cores arc arranged in parallel at 120.degree. intervals about a central axis. A series of longitudinally co-located strain sensor triplets, typically fiber Bragg gratings, are positioned along the length of each fiber at known intervals. A tunable laser interrogates the sensors to detect strain on the fiber cores. Software determines the strain magnitude (.DELTA.L/L) for each fiber at a given triplet, but then applies beam theory to calculate curvature, beading angle and torsion of the fiber bundle, and from there it determines the shape of the fiber in s Cartesian coordinate system by solving a series of ordinary differential equations expanded from the Frenet-Serrat equations. This approach eliminates the need for computationally time-intensive curve-tilting and allows the three-dimensional shape of the optical fiber assembly to be displayed in real-time.

Nonlinear effects of a modal domain optical fiber sensor in a vibration suppression control loop for a flexible structure

NASA Technical Reports Server (NTRS)

Lindner, D. K.; Zvonar, G. A.; Baumann, W. T.; Delos, P. L.

1993-01-01

Recently, a modal domain optical fiber sensor has been demonstrated as a sensor in a control system for vibration suppression of a flexible cantilevered beam. This sensor responds to strain through a mechanical attachment to the structure. Because this sensor is of the interferometric type, the output of the sensor has a sinusoidal nonlinearity. For small levels of strain, the sensor can be operated in its linear region. For large levels of strain, the detection electronics can be configured to count fringes. In both of these configurations, the sensor nonlinearity imposes some restrictions on the performance of the control system. In this paper we investigate the effects of these sensor nonlinearities on the control system, and identify the region of linear operation in terms of the optical fiber sensor parameters.

Slab-coupled optical sensor fabrication using side-polished Panda fibers.

PubMed

King, Rex; Seng, Frederick; Stan, Nikola; Cuzner, Kevin; Josephson, Chad; Selfridge, Richard; Schultz, Stephen

2016-11-01

A new device structure used for slab-coupled optical sensor (SCOS) technology was developed to fabricate electric field sensors. This new device structure replaces the D-fiber used in traditional SCOS technology with a side-polished Panda fiber. Unlike the D-fiber SCOS, the Panda fiber SCOS is made from commercially available materials and is simpler to fabricate. The Panda SCOS interfaces easier with lab equipment and exhibits ∼3  dB less loss at link points than the D-fiber SCOS. The optical system for the D-fiber is bandwidth limited by a transimpedance amplifier (TIA) used to amplify to the electric signal. The Panda SCOS exhibits less loss than the D-fiber and, as a result, does not require as high a gain setting on the TIA, which results in an overall higher bandwidth range. Results show that the Panda sensor also achieves comparable sensitivity results to the D-fiber SCOS. Although the Panda SCOS is not as sensitive as other side-polished fiber electric field sensors, it can be fabricated much easier because the fabrication process does not require special alignment techniques, and it is made from commercially available materials.

Magnetic field sensor based on the magnetic-fluid-clad combined with singlemode-multimode-singlemode fiber and large core-offset splicing structure

NASA Astrophysics Data System (ADS)

Lv, Ri-qing; Qian, Jun-kai; Zhao, Yong

2018-03-01

A simple, compact optical fiber magnetic field sensor is proposed and experimentally demonstrated in this paper. It is based on the magnetic-fluid-clad combined with singlemode-multimode-singlemode fiber structure and large core-offset splicing structure. It was protected by a section of capillary tube and was sealed by UV glue. A sensing property study of the combined optical fiber structure and the proposed sensor were carried out. The experimental results show that the sensitivity of the refractive index of the optical fiber sensing structure is up to 156.63 nm/RIU and the magnetic field sensitivity of the proposed sensor is up to -97.24 pm/Oe in the range from 72.4 Oe to 297.8 Oe. The proposed sensor has several other advantages, such as simple structure, small size, easy fabrication and low cost.

Polymer optical fiber compound parabolic concentrator tip for enhanced coupling efficiency for fluorescence based glucose sensors

PubMed Central

Hassan, Hafeez Ul; Nielsen, Kristian; Aasmul, Soren; Bang, Ole

2015-01-01

We demonstrate that the light excitation and capturing efficiency of fluorescence based fiber-optical sensors can be significantly increased by using a CPC (Compound Parabolic Concentrator) tip instead of the standard plane-cut tip. We use Zemax modelling to find the optimum CPC tip profile and fiber length of a polymer optical fiber diabetes sensor for continuous monitoring of glucose levels. We experimentally verify the improved performance of the CPC tipped sensor and the predicted production tolerances. Due to physical size requirements when the sensor has to be inserted into the body a non-optimal fiber length of 35 mm is chosen. For this length an average improvement in efficiency of a factor of 1.7 is experimentally demonstrated and critically compared to the predicted ideal factor of 3 in terms of parameters that should be improved through production optimization. PMID:26713213

All fiber magnetic field sensor with Ferrofluid-filled tapered microstructured optical fiber interferometer.

PubMed

Deng, Ming; Huang, Can; Liu, Danhui; Jin, Wei; Zhu, Tao

2015-08-10

An ultra-compact optical fiber magnetic field sensor based on a microstructured optical fiber (MOF) modal interference and ferrofluid (FF) has been proposed and experimentally demonstrated. The magnetic field sensor was fabricated by splicing a tapered germanium-doped index guided MOF with six big holes injected with FF to two conventional single-mode fibers. The transmission spectra of the proposed sensor under different magnetic field intensities have been measured and theoretically analyzed. Due to an efficient interaction between the magnetic nanoparticles in FF and the excited cladding mode, the magnetic field sensitivity reaches up to117.9pm/mT with a linear range from 0mT to 30mT. Moreover, the fabrication process of the proposed sensor is simple, easy and cost-effective. Therefore, it will be a promising candidate for military, aviation industry, and biomedical applications, especially, for the applications where the space is limited.

Polymer optical fiber compound parabolic concentrator tip for enhanced coupling efficiency for fluorescence based glucose sensors.

PubMed

Hassan, Hafeez Ul; Nielsen, Kristian; Aasmul, Soren; Bang, Ole

2015-12-01

We demonstrate that the light excitation and capturing efficiency of fluorescence based fiber-optical sensors can be significantly increased by using a CPC (Compound Parabolic Concentrator) tip instead of the standard plane-cut tip. We use Zemax modelling to find the optimum CPC tip profile and fiber length of a polymer optical fiber diabetes sensor for continuous monitoring of glucose levels. We experimentally verify the improved performance of the CPC tipped sensor and the predicted production tolerances. Due to physical size requirements when the sensor has to be inserted into the body a non-optimal fiber length of 35 mm is chosen. For this length an average improvement in efficiency of a factor of 1.7 is experimentally demonstrated and critically compared to the predicted ideal factor of 3 in terms of parameters that should be improved through production optimization.

An embedded fibre optic sensor for impact damage detection in composite materials

NASA Astrophysics Data System (ADS)

Glossop, Neil David William

1989-09-01

A structurally embedded fiber optic damage detection sensor for composite materials is described. The system is designed specifically for the detection of barely visible damage resulting from low velocity impacts in Kevlar-epoxy laminates. By monitoring the light transmission properties of optical fiber embedded in the composite, it was shown that the integrity of the material can be accurately determined. The effect of several parameters on the sensitivity of the system was investigated, including the effect of the optical fiber orientation and depth of embedding within the composite. A novel surface was also developed for the optical fibers to ensure they will fracture at the requisite damage level. The influence of the optical fiber sensors on the tensile and compressive material properties and on the impact resistance of the laminate was also studied. Extensive experimental results from impact tests are reported and a numerical model of the impact event is presented which is able to predict and model the damage mechanism and sensor system. A new and powerful method of nondestructive evaluation for translucent composite materials based on image enhanced backlighting is also described.

Experimental investigation of RC beams using BOTDA(R)-FRP-OF

NASA Astrophysics Data System (ADS)

Zhou, Zhi; He, Jianping; Huang, Ying; Ou, Jinping

2008-04-01

Brillouin based fiber optic sensing turns to be a promising technology for Structural Health Monitoring (SHM). However, the bare optical fiber is too fragile to act as a practical sensor, so high durability and large range (large strain) Brillouin distributed sensors are in great needs in field applications. For this reason, high durable and large range optical fiber Brillouin Optical Time Domain Analysis (Reflectometer) sensors packaged by Fiber Reinforcement Polymer (FRP), named BOTDA(R)-FRP-OF, have been studied and developed. Besides, in order to study the large strain, crack and slip between the rebar and concrete in reinforced concrete (RC) beams using BOTDR(A) technique, five RC Beams installed with BOTDA(R)-FRP-OF sensors have been set up. And the damage characteristics of the RC beams were investigated by comparing the strain measured by the BOTDA(R)-FRP-OF sensors and the strain from traditional electric strain gauges and Fiber Bragg Grating (FBG) sensors, respectively. The test results show that the BOTDA(R)-FRP-OF sensor can effectively detect the damage (including crack and slip) characteristic of RC beam, and it is suitable for the long-term structural health monitoring on concrete structures such as bridge, big dam and so on.

Fiber optic medical pressure-sensing system employing intelligent self-calibration

NASA Astrophysics Data System (ADS)

He, Gang

1996-01-01

In this article, we describe a fiber-optic catheter-type pressure-sensing system that has been successfully introduced for medical diagnostic applications. We present overall sensors and optoelectronics designs, and highlight product development efforts that lead to a reliable and accurate disposable pressure-sensing system. In particular, the incorporation of an intelligent on-site self-calibration approach allows limited sensor reuses for reducing end-user costs and for system adaptation to wide sensor variabilities associated with low-cost manufacturing processes. We demonstrate that fiber-optic sensors can be cost-effectively produced to satisfy needs of certain medical market segments.

Demountable connection for polymer optical fiber grating sensors

NASA Astrophysics Data System (ADS)

Abang, Ada; Webb, David J.

2012-08-01

The authors fabricated a demountable Ferrule connector/Physical contact connection between silica fiber and a polymer optical fiber (POF) containing a fiber Bragg grating. The use of a connector for POF grating sensors eliminates the limitations of ultraviolet glued connections and increases the ease with which the devices can be applied to real-world measurement tasks.

Microbend fiber-optic temperature sensor

DOEpatents

Weiss, J.D.

1995-05-30

A temperature sensor is made of optical fiber into which quasi-sinusoidal microbends have been permanently introduced. In particular, the present invention includes a graded-index optical fiber directing steady light through a section of the optical fiber containing a plurality of permanent microbends. The microbend section of the optical fiber is contained in a thermally expansive sheath, attached to a thermally expansive structure, or attached to a bimetallic element undergoing temperature changes and being monitored. The microbend section is secured to the thermally expansive sheath which allows the amplitude of the microbends to decrease with temperature. The resultant increase in the optical fiber`s transmission thus allows temperature to be measured. The plural microbend section of the optical fiber is secured to the thermally expansive structure only at its ends and the microbends themselves are completely unconstrained laterally by any bonding agent to obtain maximum longitudinal temperature sensitivity. Although the permanent microbends reduce the transmission capabilities of fiber optics, the present invention utilizes this phenomenon as a transduction mechanism which is optimized to measure temperature. 5 figs.

Fiber-optic sensor demonstrator (FSD) for the monitoring of spacecraft subsystems on ESA's PROBA-2

NASA Astrophysics Data System (ADS)

Kruzelecky, Roman V.; Zou, Jing; Mohammed, Najeeb; Haddad, Emile; Jamroz, Wes; Ricci, Francesco; Lamorie, Joshua; Edwards, Eric; McKenzie, Iain; Vuilleumier, Pierrik

2017-11-01

MPB Communications (MPBC) is developing solutions to the monitoring requirements of spacecraft based on its fiber-laser and Fiber Bragg Grating expertise. This is cumulating in the Fiber Sensor Demonstrator for ESA's Proba-2 that is scheduled for launch in 2007. The advantages of the MPBC approach include a central interrogation system that can be used to control a variety of different fiber-optic sensors including temperature, pressure, actuator status, and propellant leakage. This paper reviews the design and ground qualification of the FSD system in preparation for integration with Proba-2. The FSD will provide monitoring for various Proba-2 subsystems, including a hybrid propulsion system. Some of the challenges associated with using fiber-optics in space are discussed.

Durability tests of a fiber optic corrosion sensor.

PubMed

Wan, Kai Tai; Leung, Christopher K Y

2012-01-01

Steel corrosion is a major cause of degradation in reinforced concrete structures, and there is a need to develop cost-effective methods to detect the initiation of corrosion in such structures. This paper presents a low cost, easy to use fiber optic corrosion sensor for practical application. Thin iron film is deposited on the end surface of a cleaved optical fiber by sputtering. When light is sent into the fiber, most of it is reflected by the coating. If the surrounding environment is corrosive, the film is corroded and the intensity of the reflected signal drops significantly. In previous work, the sensing principle was verified by various experiments in laboratory and a packaging method was introduced. In this paper, the method of multiplexing several sensors by optical time domain reflectometer (OTDR) and optical splitter is introduced, together with the interpretation of OTDR results. The practical applicability of the proposed sensors is demonstrated in a three-year field trial with the sensors installed in an aggressive marine environment. The durability of the sensor against chemical degradation and physical degradation is also verified by accelerated life test and freeze-thaw cycling test, respectively.

Colloidal gold-modified optical fiber for chemical and biochemical sensing.

PubMed

Cheng, Shu-Fang; Chau, Lai-Kwan

2003-01-01

A novel class of fiber-optic evanescent-wave sensor was constructed on the basis of modification of the unclad portion of an optical fiber with self-assembled gold colloids. The optical properties and, hence, the attenuated total reflection spectrum of self-assembled gold colloids on the optical fiber changes with different refractive index of the environment near the colloidal gold surface. With sucrose solutions of increasing refractive index, the sensor response decreases linearly. The colloidal gold surface was also functionalized with glycine, succinic acid, or biotin to enhance the selectivity of the sensor. Results show that the sensor response decreases linearly with increasing concentration of each analyte. When the colloidal gold surface was functionalized with biotin, the detection limit of the sensor for streptavidin was 9.8 x 10(-11) M. Using this approach, we demonstrate proof-of-concept of a class of refractive index sensor that is sensitive to the refractive index of the environment near the colloidal gold surface and, hence, is suitable for label-free detection of molecular or biomolecular binding at the surface of gold colloids.

Lag compensation of optical fibers or thermocouples to achieve waveform fidelity in dynamic gas pyrometry

NASA Technical Reports Server (NTRS)

Warshawsky, I.

1991-01-01

Fidelity of waveform reproduction requires constant amplitude ratio and constant time lag of a temperature sensor's indication, at all frequencies of interest. However, heat-transfer type sensors usually cannot satisfy these requirements. Equations for the actual indication of a thermocouple and an optical-fiber pyrometer are given explicitly, in terms of sensor and flowing-gas properties. A practical, realistic design of each type of sensor behaves like a first-order system with amplitude-ratio attenuation inversely proportional to frequency when the frequency exceeds the corner frequency. Only at much higher frequencies does the amplitude-ratio attenuation for the optical fiber sensor become inversely proportional to the square root of the frequency. Design options for improving the frequency response are discussed. On-line electrical lag compensation, using a linear amplifier and a passive compensation network, can extend the corner frequency of the thermocouple 100-fold or more; a similar passive network can be used for the optical-fiber sensor. Design details for these networks are presented.

Silicon-etalon fiber-optic temperature sensor

NASA Technical Reports Server (NTRS)

Beheim, Glenn; Fritsch, Klaus; Flatico, Joseph M.; Azar, Massood Tabib

1989-01-01

A temperature sensor is described which consists of a silicon etalon that is sputtered directly onto the end of an optical fiber. A two-layer protective cap structure is used to improve the sensor's long-term stability. The sensor's output is wavelength encoded to provide a high degree of immunity from cable and connector effects. This sensor is extremely compact and potentially inexpensive.

Sensitive Leptospira DNA detection using tapered optical fiber sensor.

PubMed

Zainuddin, Nurul H; Chee, Hui Y; Ahmad, Muhammad Z; Mahdi, Mohd A; Abu Bakar, Muhammad H; Yaacob, Mohd H

2018-03-23

This paper presents the development of tapered optical fiber sensor to detect a specific Leptospira bacteria DNA. The bacteria causes Leptospirosis, a deadly disease but with common early flu-like symptoms. Optical single mode fiber (SMF) of 125 μm diameter is tapered to produce 12 μm waist diameter and 15 cm length. The novel DNA-based optical fiber sensor is functionalized by incubating the tapered region with sodium hydroxide (NaOH), (3-Aminopropyl) triethoxysilane and glutaraldehyde. Probe DNA is immobilized onto the tapered region and subsequently hybridized by its complementary DNA (cDNA). The transmission spectra of the DNA-based optical fiber sensor are measured in the 1500 to 1600 nm wavelength range. It is discovered that the shift of the wavelength in the SMF sensor is linearly proportional with the increase in the cDNA concentrations from 0.1 to 1.0 nM. The sensitivity of the sensor toward DNA is measured to be 1.2862 nm/nM and able to detect as low as 0.1 fM. The sensor indicates high specificity when only minimal shift is detected for non-cDNA testing. The developed sensor is able to distinguish between actual DNA of Leptospira serovars (Canicola and Copenhageni) against Clostridium difficile (control sample) at very low (femtomolar) target concentrations. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Packaging optical sensors for the real world

NASA Astrophysics Data System (ADS)

Kachmar, Wayne; Nardone, Kenneth C.

2007-09-01

Optical fiber based sensing has now moved from laboratory demonstrations to actual applications in the real world. This has necessitated an entirely new area of extrusion - the packaging (cabling) of optical fibers and sensor arrays to protect them from the intended environment and installation handling while not masking or attenuating the phenomenon that is being sensed. Although each application presents new and unique challenges, the goal is to create a packaging concept for fiber sensors. Fiber sensing applications can be narrowed down to the five items below: 1. Conventional cable packages 2. Assembled (typically by hand) discrete sensor packages 3. Package enhanced sensors (where the packaging improves the effect of the sensor) 4. Linear sensor installation packaging 5. Scalar packaging (where the cabling adds to the range of the sensor) The above applications can be accomplished in a number of ways, and methods are still being developed in this relatively new science. Some of the new technology methods being explored include: UV cured liquids; Voided space cores; Conventional cable extrusion & its determination of mechanical characteristics. This paper reviews the pluses and minuses of the above methods and how their combination ultimately determines how the fiber or sensor array is to be jacketed in order to meet the specific application requirements. This paper will also review non-standard material characteristics, strength members and their role in measuring strain and stress values along with the overall influence of packaging on optical fibers and sensor arrays.

Fiber-Optic Linear Displacement Sensor Based On Matched Interference Filters

NASA Astrophysics Data System (ADS)

Fuhr, Peter L.; Feener, Heidi C.; Spillman, William B.

1990-02-01

A fiber optic linear displacement sensor has been developed in which a pair of matched interference filters are used to encode linear position on a broadband optical signal as relative intensity variations. As the filters are displaced, the optical beam illuminates varying amounts of each filter. Determination of the relative intensities at each filter pairs' passband is based on measurements acquired with matching filters and photodetectors. Source power variation induced errors are minimized by basing determination of linear position on signal Visibility. A theoretical prediction of the sensor's performance is developed and compared with experiments performed in the near IR spectral region using large core multimode optical fiber.

Dynamic response of tapered optical multimode fiber coated with carbon nanotubes for ethanol sensing application.

PubMed

Shabaneh, Arafat; Girei, Saad; Arasu, Punitha; Mahdi, Mohd; Rashid, Suraya; Paiman, Suriati; Yaacob, Mohd

2015-05-04

Ethanol is a highly combustible chemical universally designed for biomedical applications. In this paper, optical sensing performance of tapered multimode fiber tip coated with carbon nanotube (CNT) thin film towards aqueous ethanol with different concentrations is investigated. The tapered optical multimode fiber tip is coated with CNT using drop-casting technique and is annealed at 70 °C to enhance the binding of the nanomaterial to the silica fiber tip. The optical fiber tip and the CNT sensing layer are micro-characterized using FESEM and Raman spectroscopy techniques. When the developed sensor was exposed to different concentrations of ethanol (5% to 80%), the sensor reflectance reduced proportionally. The developed sensors showed high sensitivity, repeatability and fast responses (<55 s) towards ethanol.

Dynamic Response of Tapered Optical Multimode Fiber Coated with Carbon Nanotubes for Ethanol Sensing Application

PubMed Central

Shabaneh, Arafat; Girei, Saad; Arasu, Punitha; Mahdi, Mohd; Rashid, Suraya; Paiman, Suriati; Yaacob, Mohd

2015-01-01

Ethanol is a highly combustible chemical universally designed for biomedical applications. In this paper, optical sensing performance of tapered multimode fiber tip coated with carbon nanotube (CNT) thin film towards aqueous ethanol with different concentrations is investigated. The tapered optical multimode fiber tip is coated with CNT using drop-casting technique and is annealed at 70 °C to enhance the binding of the nanomaterial to the silica fiber tip. The optical fiber tip and the CNT sensing layer are micro-characterized using FESEM and Raman spectroscopy techniques. When the developed sensor was exposed to different concentrations of ethanol (5% to 80%), the sensor reflectance reduced proportionally. The developed sensors showed high sensitivity, repeatability and fast responses (<55 s) towards ethanol. PMID:25946634

[Spectral characteristics of refractive index based on nanocoated optical fiber F-P sensor].

PubMed

Jiang, Ming-Shun; Li, Qiu-Shun; Sui, Qing-Mei; Jia, Lei; Peng, Peng

2013-01-01

An optical fiber Fabry-Perot (F-P) interferometer end surface was modified using layer-by-layer assembly and chemical covalent cross linking method, and the refractive index (RI) response characteristics of coated optical fiber F-P sensor were experimentally studied. Poly diallyldimethylammonium chloride (PDDA) and sodium polystyrene sulfonate (PSS) were chosen as nano-film materials. With the numbers of layers increasing, the reflection spectral contrast of optical fiber F-P sensor presents from high to low, then to high regularity. And the reflection spectral contrast has good temperature stability. The reflection spectra of the optical F-P sensor coated with 20 bilayers for a series of concentration of sucrose and inorganic solution were measured. Experimental results show that the inflection point extends from 1.457 to 1.462 3, and the reflection spectral contrast sensitivity to low RI material and high RI material is 24.53 and 3.60 dB x RI(-1), respectively, with good linearity. The results demonstrate that the functional coated optical F-P sensor provides a new method for biology and chemical material test.

Optical position sensor for determining the interface between a clear and an opaque fluid

DOEpatents

Weiss, Jonathan D [Albuquerque, NM

2006-05-23

An inexpensive, optical position sensor for measuring a position or length, x, along a one-dimensional curvilinear, coordinate system. The sensor can be used, for example, to determine the position of an interface between a clear and an opaque fluid (such as crude oil and water). In one embodiment, the sensor utilizes the principle of dual-fluorescence, where a primary fiber emits primary fluorescent light and a parallel secondary fiber collects a portion of the primary fluorescent light that is not blocked by the opaque fluid. This, in turn, excites secondary fluorescence in the secondary fiber at a longer wavelength. A light detector measures the intensity of secondary fluorescence emitted from an end of the secondary fiber, which is used to calculate the unknown position or length, x. Side-emitting fibers can be used in place of, or in addition to, fluorescent fibers. The all-optical sensor is attractive for applications involving flammable liquids.

Fiber Fabry-Perot Force Sensor with Small Volume and High Performance for Assessing Fretting Damage of Steam Generator Tubes

PubMed Central

Huang, Peijian; Wang, Ning; Li, Junying; Zhu, Yong; Zhang, Jie

2017-01-01

Measuring the radial collision force between the steam generator tube (SGT) and the tube support plate (TSP) is essential to assess the fretting damage of the SGT. In order to measure the radial collision force, a novel miniaturized force sensor based on fiber Fabry-Perot (F-P) was designed, and the principle and characteristics of the sensor were analyzed in detail. Then, the F-P force sensor was successfully fabricated and calibrated, and the overall dimensions of the encapsulated fiber F-P sensor were 17 mm × 5 mm × 3 mm (L × W × H). The sensor works well in humid, high pressure (10 MPa), high temperature (350 °C), and vibration (40 kHz) environments. Finally, the F-P force sensors were installed in a 1:1 steam generator test loop, and the radial collision force signals between the SGT and the TSP were obtained. The experiments indicated that the F-P sensor with small volume and high performance could help in assessing the fretting damage of the steam generator tubes. PMID:29236087

Optical Tip Clearance Measurements as a Tool for Rotating Disk Characterization

PubMed Central

García, Iker; Zubia, Joseba; Beloki, Josu; Arrue, Jon; Durana, Gaizka; Aldabaldetreku, Gotzon

2017-01-01

An experimental investigation on the vibrational behavior of a rotating disk by means of three optical fiber sensors is presented. The disk, which is a scale model of the real disk of an aircraft engine, was assembled in a wind tunnel in order to simulate real operation conditions. The pressure difference between the upstream and downstream sides of the disk causes an airflow that might force the disk to vibrate. To characterize this vibration, a set of parameters was determined by measuring the tip clearance of the disk: the amplitude, the frequency and the number of nodal diameters in the disk. All this information allowed the design of an upgraded prototype of the disk, whose performance was also characterized by the same method. An optical system was employed for the measurements, in combination with a strain gauge mounted on the disk surface, which served to confirm the results obtained. The data of the strain gauge coincided closely with those provided by the optical fiber sensors, thus demonstrating the suitability of this innovative technique to evaluate the vibrational behavior of rotating disks. PMID:28098845

The effect of force on laser fiber burnback during lithotripsy

NASA Astrophysics Data System (ADS)

Aryaei, Ashkan; Chia, Ray; Peng, Steven

2018-02-01

Optical fibers for lithotripsy are designed to deliver the maximum energy precisely to the treatment site without a decrease in performance and without increasing the risks to patients and users. One of the obstacles to constant energy delivery is burnback of the optical fiber tip. So far, researchers identified mechanical, thermal, and optical factors as mechanisms in burnback phenomena. Among mechanical factors, the force applied by urologists against a stone is expected to play a dominant role in burnback. In this study, we introduce a novel technique to measure accurately the stone depth and volume ablation under varying force. Our results show varying burnback lengths on the optical fibers and varying stone depth and volume ablation depending on the optical fiber core size. For instance, the slope of the burnback as a function of the applied force for 273 μm fibers was more than two times higher than for the 550 μm fibers. The slope of the total volume of stone ablated as function of force for 550 μm fibers was almost twice as much as for the 273 μm fibers. The data suggest urologists can maximize the stone ablation rate and minimize fiber tip burnback by controlling the applied force on the optical fiber during a lithotripsy procedure.

Tuning operating point of extrinsic Fabry-Perot interferometric fiber-optic sensors using microstructured fiber and gas pressure.

PubMed

Tian, Jiajun; Zhang, Qi; Fink, Thomas; Li, Hong; Peng, Wei; Han, Ming

2012-11-15

Intensity-based demodulation of extrinsic Fabry-Perot interferometric (EFPI) fiber-optic sensors requires the light wavelength to be on the quadrature point of the interferometric fringes for maximum sensitivity. In this Letter, we propose a novel and remote operating-point tuning method for EFPI fiber-optic sensors using microstructured fibers (MFs) and gas pressure. We demonstrated the method using a diaphragm-based EFPI sensor with a microstructured lead-in fiber. The holes in the MF were used as gas channels to remotely control the gas pressure inside the Fabry-Perot cavity. Because of the deformation of the diaphragm with gas pressure, the cavity length and consequently the operating point can be remotely tuned for maximum sensitivity. The proposed operating-point tuning method has the advantage of reduced complexity and cost compared to previously reported methods.

Monitoring of shallow landslides by distributed optical fibers: insights from a physical model

NASA Astrophysics Data System (ADS)

Luca, Schenato; Matteo, Camporese; Luca, Palmieri; Alessandro, Pasuto; Salandin, Paolo

2017-04-01

Shallow landslides represent an extreme risk for individuals and structures due to their fast propagation and the very short time between appearance of warning signs and collapse. A lot of attention has been paid in the last decades to the analysis of activation mechanisms and to the implementation of appropriate early warning systems. Intense rainfall, stream erosion, flash floods, etc, are only few of the possible triggering factors that have been identified. All those factors may induce an increase in the forces acting and/or in the pore water pressure that eventually trigger the collapse. Due to the decrease of the shear resistance of soils, significant stresses develop at the sliding surface, determining local anomalous strain even before the collapse. This highlights the importance of monitoring the early appearance of hazardous strain fields. In light of the intrinsic lack of control and reproducibility in real cases, strain sensors have been applied in small-scale physical models and testbeds. Nonetheless, it has been observed that a reliable correlation between the landslide evolution and the strain field can be determined only by using minimally invasive sensors, while comprehensive information can be achieved at the cost of very fine spatial sampling, which represents the primary issue with small-to-medium scale physical models. It is evident how the two requirements, i.e., minimal invasiveness and high spatial resolution, are a limiting factor for standard sensor technology. In this regard, strain is one of the first variable addressed by optical fiber sensors, yet only recently for geotechnical applications and in very few case for landslide monitoring. In particular, the technology of distributed fiber optic sensors, with centimeter scale resolution, has the potential to address the aforementioned needs of small scale physical testing. In this work, for the first time, the strain field at the failure surface of a shallow landslide, reproduced in an artificial experimental hillslope, has been monitored by a distributed optical fiber sensing system based on optical fiber domain reflectometry with centimeter spatial resolution. The optical sensing system has been integrated with hydrological sensors for pore water pressure and moisture content, to the aim of supporting the data analysis. From the whole monitoring system a thorough knowledge of the collapsing mechanism has been achieved and it has been possible to identify precursory signs of the soil collapse well before its actual occurrence. The deployment of the sensing system and analysis of the collected data are discussed, together with possible potential for field installation.

Characterization of Scintillating X-ray Optical Fiber Sensors

PubMed Central

Sporea, Dan; Mihai, Laura; Vâţă, Ion; McCarthy, Denis; O'Keeffe, Sinead; Lewis, Elfed

2014-01-01

The paper presents a set of tests carried out in order to evaluate the design characteristics and the operating performance of a set of six X-ray extrinsic optical fiber sensors. The extrinsic sensor we developed is intended to be used as a low energy X-ray detector for monitoring radiation levels in radiotherapy, industrial applications and for personnel dosimetry. The reproducibility of the manufacturing process and the characteristics of the sensors were assessed. The sensors dynamic range, linearity, sensitivity, and reproducibility are evaluated through radioluminescence measurements, X-ray fluorescence and X-ray imaging investigations. Their response to the operating conditions of the excitation source was estimated. The effect of the sensors design and implementation, on the collecting efficiency of the radioluminescence signal was measured. The study indicated that the sensors are efficient only in the first 5 mm of the tip, and that a reflective coating can improve their response. Additional tests were done to investigate the concentricity of the sensors tip against the core of the optical fiber guiding the optical signal. The influence of the active material concentration on the sensor response to X-ray was studied. The tests were carried out by measuring the radioluminescence signal with an optical fiber spectrometer and with a Multi-Pixel Photon Counter. PMID:24556676

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

PubMed Central

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

2012-01-01

A highly porous optical-fiber cladding was developed for evanescent-wave fiber sensors, which contains sensor molecules, maintains guiding conditions in the optical fiber, and is suitable for sensing in aqueous environments. To make the cladding material (a poly(ethylene) glycol diacrylate (PEGDA) polymer) highly porous, a microsphere templating strategy was employed. The resulting pore network increases transport of the target analyte to the sensor molecules located in the cladding, which improves the sensor response time. This was demonstrated using fluorescein-based pH sensor molecules, which were covalently attached to the cladding material. Scanning electron microscopy was used to examine the structure of the templated polymer and the large network of interconnected pores. Fluorescence measurements showed a tenfold improvement in the response time for the templated polymer and a reliable pH response over a pH range of five to nine with an estimated accuracy of 0.08 pH units. PMID:22654644

Fiber Optic Geophysics Sensor Array

NASA Astrophysics Data System (ADS)

Grochowski, Lucjan

1989-01-01

The distributed optical sensor arrays are analysed in view of specific needs of 3-D seismic explorations methods. There are compared advantages and disadventages of arrays supported by the sensors which are modulated in intensity and phase. In these systems all-fiber optic structures and their compabilities with digital geophysic formats are discussed. It was shown that the arrays based on TDM systems with the intensity modulated sensors are economically and technically the best matched for geophysic systems supported by a large number of the sensors.

Effective light coupling in reflective fiber optic distance sensors using a double-clad fiber

NASA Astrophysics Data System (ADS)

Werzinger, Stefan; Härteis, Lisa; Köhler, Aaron; Engelbrecht, Rainer; Schmauss, Bernhard

2017-04-01

Many fiber optic distance sensors use a reflective configuration, where a light beam is launched from an optical fiber, reflected from a target and coupled back into the fiber. While singlemode fibers (SMF) provide low-loss, high-performance components and a well-defined output beam, the coupling of the reflected light into the SMF is very sensitive to mechanical misalignments and scattering at the reflecting target. In this paper we use a double-clad fiber (DCF) and a DCF coupler to obtain an enhanced multimodal coupling of reflected light into the fiber. Increased power levels and robustness are achieved compared to a pure SMF configuration.

Using a fiber loop and fiber bragg grating as a fiber optic sensor to simultaneously measure temperature and displacement.

PubMed

Chang, Yao-Tang; Yen, Chih-Ta; Wu, Yue-Shiun; Cheng, Hsu-Chih

2013-05-16

This study integrated a fiber loop manufactured by using commercial fiber (SMF-28, Corning) and a fiber Bragg grating (FBG) to form a fiber optic sensor that could simultaneously measure displacement and temperature. The fiber loop was placed in a thermoelectric cooling module with FBG affixed to the module, and, consequently, the center wavelength displacement of FBG was limited by only the effects of temperature change. Displacement and temperature were determined by measuring changes in the transmission of optical power and shifts in Bragg wavelength. This study provides a simple and economical method to measure displacement and temperature simultaneously.

Fiber optic sensors for infrastructure applications

DOT National Transportation Integrated Search

1998-02-01

Fiber optic sensor technology offers the possibility of implementing "nervous systems" for infrastructure elements that allow high performance, cost effective health and damage assessment systems to be achieved. This is possible, largely due to syner...

Alcohol sensor based on u-bent hetero-structured fiber optic

NASA Astrophysics Data System (ADS)

Patrialova, Sefi N.; Hatta, Agus M.; Sekartedjo, Sekartedjo

2016-11-01

A sensor based on a fiber optic hetero-structure to determine the concentration of alcohol has been proposed. The structure of the sensing probe in this research is a singlemode-multimode-singlemode (SMS) which bent into Ushaped and soon called as SMS u-bent. The SMS structure was chosen to get a higher sensitivity. This research utilizes the principle of multimode interference and evanescent field by modifying the cladding with various alcohol concentration. Testing of the sensor's performance has been done by measuring the sensor's power output response to the length of the SMS fiber optic, bending diameter, and alcohol concentration. Based on the experiment result, the ubent SMS fiber optic with 50 mm bending diameter and 63 mm MMF lenght has the highest sensitivity, 3.87 dB/% and the minimum resolution, 0.26 x 10-3 %.

Dopants concentration effects on the wavelength shift of long-period fiber gratings used as liquid level detectors

NASA Astrophysics Data System (ADS)

Mao, Barerem-Melgueba; Zhou, Bin

2011-12-01

Two liquid level sensors based on different long-period fiber gratings are proposed and compared. The long-period gratings have the same characteristics (length, grating period) but are fabricated in different optical fibers (photosensitive B-Ge codoped optical fibers with different dopants concentrations). The principle of this type of sensor is based on the refractive index sensitivity of long-period fiber gratings. By monitoring the resonant wavelength shifts of a given attenuation band, one can measure the immersed lengths of long-period fiber gratings and then the liquid level. The levels of two different solutions are measured. The maximum shift (7.69 nm) of the investigated resonance wavelength was observed in LPG1 (fabricated in Fibercore PS1250/1500). By controlling the fiber dopants concentrations one can improve the readouts of a fiber-optic liquid level sensor based on long-period fiber gratings.

Optical state-of-charge monitor for batteries

DOEpatents

Weiss, Jonathan D.

1999-01-01

A method and apparatus for determining the instantaneous state-of-charge of a battery in which change in composition with discharge manifests itself as a change in optical absorption. In a lead-acid battery, the sensor comprises a fiber optic system with an absorption cell or, alternatively, an optical fiber woven into an absorbed-glass-mat battery. In a lithium-ion battery, the sensor comprises fiber optics for introducing light into the anode to monitor absorption when lithium ions are introduced.

Embedded spectroscopic fiber sensor for on-line arc-welding analysis.

PubMed

Mirapeix, Jesús; Cobo, Adolfo; Quintela, Antonio; López-Higuera, José-Miguel

2007-06-01

A new fiber sensor system designed for spectroscopic analysis and on-line quality assurance of arc-welding processes is presented here. Although several different approaches have been considered for the optical capture of plasma emission in arc-welding processes, they tend to be invasive and make use of optical devices such as collimators or photodiodes. The solution proposed here is based on the arrangement of an optical fiber, which is used at the same time as the optical capturing device and also to deliver the optical information to a spectrometer, embedded within an arc-welding torch. It will be demonstrated that, by using the shielding gas as a protection for the fiber end, the plasma light emission is efficiently collected, forming a sensor system completely transparent and noninvasive for the welding operator. The feasibility of the proposed sensor designed to be used as the input optics of a welding quality-assurance system based on plasma spectroscopy will be demonstrated by means of several welding tests.

Lensless magneto-optic speed sensor

DOEpatents

Veeser, L.R.; Forman, P.R.; Rodriguez, P.J.

1998-02-17

Lensless magneto-optic speed sensor is disclosed. The construction of a viable Faraday sensor has been achieved. Multimode fiber bundles are used to collect the light. If coupled directly into a 100 or 200 {micro}m core fiber, light from a light emitting diode (LED) is sufficient to operate the sensor. In addition, LEDs ensure that no birefringence effects in the input fiber are possible, as the output from such light sources have random polarization. No lens is required since the large diameter optical fibers and thin crystals of materials having high Verdet constants (such as iron garnets) employed permit the collection of a substantial quantity of light. No coupler is required. The maximum amount of light which could reach a detector using a coupler is 25%, while the measured throughput of the fiber-optic bundle without a coupler is about 42%. All of the elements employed in the present sensor are planar, and no particular orientation of these elements is required. The present sensor operates over a wide range of distances from magnetic field sources, and observed signals are large. When a tone wheel is utilized, the signals are independent of wheel speed, and the modulation is observed to be about 75%. No sensitivity to bends in the input or output optical fiber leads was observed. Reliable operation was achieved down to zero frequency, or no wheel rotation. 5 figs.

Lensless Magneto-optic speed sensor

DOEpatents

Veeser, Lynn R.; Forman, Peter R.; Rodriguez, Patrick J.

1998-01-01

Lensless magneto-optic speed sensor. The construction of a viable Faraday sensor has been achieved. Multimode fiber bundles are used to collect the light. If coupled directly into a 100 or 200 .mu.m core fiber, light from a light emitting diode (LED) is sufficient to operate the sensor. In addition, LEDs ensure that no birefringence effects in the input fiber are possible, as the output from such light sources have random polarization. No lens is required since the large diameter optical fibers and thin crystals of materials having high Verdet constants (such as iron garnets) employed permit the collection of a substantial quantity of light. No coupler is required. The maximum amount of light which could reach a detector using a coupler is 25%, while the measured throughput of the fiber-optic bundle without a coupler is about 42%. All of the elements employed in the present sensor are planar, and no particular orientation of these elements is required. The present sensor operates over a wide range of distances from magnetic field sources, and observed signals are large. When a tone wheel is utilized, the signals are independent of wheel speed, and the modulation is observed to be about 75%. No sensitivity to bends in the input or output optical fiber leads was observed. Reliable operation was achieved down to zero frequency, or no wheel rotation.

Strain distribution in thin concrete pavement panels under three-point loading to failure with pre-pulse-pump Brillouin optical time domain analysis (Presentation Video)

NASA Astrophysics Data System (ADS)

Bao, Yi; Cain, John; Chen, Yizheng; Huang, Ying; Chen, Genda; Palek, Leonard

2015-04-01

Thin concrete panels reinforced with alloy polymer macro-synthetic fibers have recently been introduced to rapidly and cost-effectively improve the driving condition of existing roadways by laying down a fabric sheet on the roadways, casting a thin layer of concrete, and then cutting the layer into panels. This study is aimed to understand the strain distribution and potential crack development of concrete panels under three-point loading. To this end, six full-size 6ft×6ft×3in concrete panels were tested to failure in the laboratory. They were instrumented with three types of single-mode optical fiber sensors whose performance and ability to measure the strain distribution and detect cracks were compared. Each optical fiber sensor was spliced and calibrated, and then attached to a fabric sheet using adhesive. A thin layer of mortar (0.25 ~ 0.5 in thick) was cast on the fabric sheet. The three types of distributed sensors were bare SM-28e+ fiber, SM-28e+ fiber with a tight buffer, and concrete crack cable, respectively. The concrete crack cable consisted of one SM-28e+ optical fiber with a tight buffer, one SM-28e+ optical fiber with a loose buffer for temperature compensation, and an outside protective tight sheath. Distributed strains were collected from the three optical fiber sensors with pre-pulse-pump Brillouin optical time domain analysis in room temperature. Among the three sensors, the bare fiber was observed to be most fragile during construction and operation, but most sensitive to strain change or micro-cracks. The concrete crack cable was most rugged, but not as sensitive to micro-cracks and robust in micro-crack measurement as the bare fiber. The ruggedness and sensitivity of the fiber with a tight buffer were in between the bare fiber and the concrete crack cable. The strain distribution resulted from the three optical sensors are in good agreement, and can be applied to successfully locate cracks in the concrete panels. It was observed that the three types of fibers were functional until the concrete panels have experienced inelastic deformation, making the distributed strain sensing technology promising for real applications in pavement engineering.

Micro-controller based air pressure monitoring instrumentation system using optical fibers as sensor

NASA Astrophysics Data System (ADS)

Hazarika, D.; Pegu, D. S.

2013-03-01

This paper describes a micro-controller based instrumentation system to monitor air pressure using optical fiber sensors. The principle of macrobending is used to develop the sensor system. The instrumentation system consists of a laser source, a beam splitter, two multi mode optical fibers, two Light Dependent Resistance (LDR) based timer circuits and a AT89S8252 micro-controller. The beam splitter is used to divide the laser beam into two parts and then these two beams are launched into two multi mode fibers. One of the multi mode fibers is used as the sensor fiber and the other one is used as the reference fiber. The use of the reference fiber is to eliminate the environmental effects while measuring the air pressure magnitude. The laser beams from the sensor and reference fibers are applied to two identical LDR based timer circuits. The LDR based timer circuits are interfaced to a micro-controller through its counter pins. The micro-controller samples the frequencies of the timer circuits using its counter-0 and counter-1 and the counter values are then processed to provide the measure of air pressure magnitude.

Fiber Optics Instrumentation Development

NASA Technical Reports Server (NTRS)

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

2010-01-01

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

The honey insertion cladding to improve the sensitivity of temperature polymer optical fiber sensor

NASA Astrophysics Data System (ADS)

Arwani, M.; Kuswanto, H.

2018-04-01

The sensitivity of temperature polymer optical fiber (POF) sensor has been studied. Part of cladding (9 cm) was substituted with honey. Polymer cladding was stripped mechanically and the honey inserted into the tube. Plastic gel closed the two end sides of the tubes. The optical power output was detected by Optical Power Meter (OPM). Honey cladding and temperature changing effect to the internal reflection and optical fiber output intensity. Highest output intensity changing at 20°C was shown by optical fiber coated by longan honey as cladding. The range of 10-50° C, as the rise of surroundings temperature, the attenuation was getting smaller. Best sensitivity was fiber with sensing part coated by Longan honey. Best linearity was sensing fiber with sensing part coated by Pracimantoro honey.

Microstructured Optical Fiber-based Biosensors: Reversible and Nanoliter-Scale Measurement of Zinc Ions.

PubMed

Heng, Sabrina; McDevitt, Christopher A; Kostecki, Roman; Morey, Jacqueline R; Eijkelkamp, Bart A; Ebendorff-Heidepriem, Heike; Monro, Tanya M; Abell, Andrew D

2016-05-25

Sensing platforms that allow rapid and efficient detection of metal ions would have applications in disease diagnosis and study, as well as environmental sensing. Here, we report the first microstructured optical fiber-based biosensor for the reversible and nanoliter-scale measurement of metal ions. Specifically, a photoswitchable spiropyran Zn(2+) sensor is incorporated within the microenvironment of a liposome attached to microstructured optical fibers (exposed-core and suspended-core microstructured optical fibers). Both fiber-based platforms retains high selectivity of ion binding associated with a small molecule sensor, while also allowing nanoliter volume sampling and on/off switching. We have demonstrated that multiple measurements can be made on a single sample without the need to change the sensor. The ability of the new sensing platform to sense Zn(2+) in pleural lavage and nasopharynx of mice was compared to that of established ion sensing methodologies such as inductively coupled plasma mass spectrometry (ICP-MS) and a commercially available fluorophore (Fluozin-3), where the optical-fiber-based sensor provides a significant advantage in that it allows the use of nanoliter (nL) sampling when compared to ICP-MS (mL) and FluoZin-3 (μL). This work paves the way to a generic approach for developing surface-based ion sensors using a range of sensor molecules, which can be attached to a surface without the need for its chemical modification and presents an opportunity for the development of new and highly specific ion sensors for real time sensing applications.

Fiber optical sensor system for shape and haptics for flexible instruments in minimally invasive surgery: overview and status quo

NASA Astrophysics Data System (ADS)

Ledermann, Christoph; Pauer, Hendrikje; Woern, Heinz

2014-05-01

In minimally invasive surgery, exible mechatronic instruments promise to improve the overall performance of surgical interventions. However, those instruments require highly developed sensors in order to provide haptic feedback to the surgeon or to enable (semi-)autonomous tasks. Precisely, haptic sensors and a shape sensor are required. In this paper, we present our ber optical sensor system of Fiber Bragg Gratings, which consists of a shape sensor, a kinesthetic sensor and a tactile sensor. The status quo of each of the three sensors is described, as well as the concept to integrate them into one ber optical sensor system.

Research of pressure sensor based on the fiber Bragg grating for permanent downwell monitoring application

NASA Astrophysics Data System (ADS)

Liu, Lina; Long, Pin; Liu, Tiegen

2004-11-01

Timely, accurate and reliable pressure information about how the reservoir is performing is an important component to optimizing oil yield and production rates. This paper reviews the use of fiber optical pressure sensor for downhole monitoring in the oil industry. Several types of pressure transducer with different characteristics have been introduced. Due to their multiplexing capabilities and versatility ,the use of Bragg grating sensors appears to be particularly suited for this application. A sensor for accurate and long term fluid pressure monitoring based on optical fiber Bragg gratings(FBGs) is developed. The sensor converts fluid pressure into optical fiber strain by means of a mechanical transducer to enhance its sensitivity to pressure. It can also implement distributed or multiplexed sensing. The sensor operation is studied at pressure up to 100 Mpa(1000bar) and the tested temperature to ~175°. It is possible to be used in the well.

Fiber Optic Sensors for Structural Health Monitoring of Air Platforms

PubMed Central

Guo, Honglei; Xiao, Gaozhi; Mrad, Nezih; Yao, Jianping

2011-01-01

Aircraft operators are faced with increasing requirements to extend the service life of air platforms beyond their designed life cycles, resulting in heavy maintenance and inspection burdens as well as economic pressure. Structural health monitoring (SHM) based on advanced sensor technology is potentially a cost-effective approach to meet operational requirements, and to reduce maintenance costs. Fiber optic sensor technology is being developed to provide existing and future aircrafts with SHM capability due to its unique superior characteristics. This review paper covers the aerospace SHM requirements and an overview of the fiber optic sensor technologies. In particular, fiber Bragg grating (FBG) sensor technology is evaluated as the most promising tool for load monitoring and damage detection, the two critical SHM aspects of air platforms. At last, recommendations on the implementation and integration of FBG sensors into an SHM system are provided. PMID:22163816

Infrared-fiber-optic fire sensor developments - Role of measurement uncertainty in evaluation of background limited range. [in spacecraft safety

NASA Technical Reports Server (NTRS)

Tapphorn, Ralph M.; Kays, Randy; Porter, Alan

1989-01-01

Fire-detector systems based on distributed infrared fiber-sensors have been investigated for potential applications in the aerospace industry. Responsivities to blackbody and flame radiations were measured with various design configurations of an infrared fiber-optic sensor. Signal processing techniques were also investigated, and the results show significant differences in the fire-sensor performance depending on the design configuration. Measurement uncertainties were used to determine the background-limited ranges for the various fire-sensor concepts, and the probability of producing false alarms caused by fluctuations in the background signals were determined using extreme probability theory. The results of the research show that infrared fiber-optic fire sensors are feasible for application on manned spacecraft; however, additional development work will be required to eliminate false alarms caused by high temperature objects such as incandescent lamps.