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Sample records for fiber optic temperature

  1. 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.

  2. 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.

  3. Fiber optic temperature sensor

    NASA Technical Reports Server (NTRS)

    Morey, W. W.; Glenn, W. H.; Snitzer, E.

    1983-01-01

    A temperature sensor has been developed that utilizes the temperature dependent absorption of a rare earth doped optical fiber. The temperature measurement is localized at a remote position by splicing a short section of the rare earth fiber into a loop of commercial data communication fiber that sends and returns an optical probe signal to the temperature sensitive section of fiber. The optical probe signal is generated from two different wavelength filtered LED sources. A four port fiber optic coupler combines the two separate wavelength signals into the fiber sensing loop. Time multiplexing is used so that each signal wavelength is present at a different time. A reference signal level measurement is also made from the LED sources and a ratio taken with the sensor signal to produce a transmission measurement of the fiber loop. The transmission is affected differently at each wavelength by the rare earth temperature sensitive fiber. The temperature is determined from a ratio of the two transmission measurements. This method eliminates any ambiguity with respect to changes in signal level in the fiber loop such as mating and unmating optical connectors. The temperature range of the sensor is limited to about 800 C by the temperature limit fo the feed fibers.

  4. Fiber-optic temperature sensor

    SciTech Connect

    O`Rourke, P.E.; Livingston, R.R.; Jantzen, C.M.; Ramsey, W.G.; Hopkins, C.D.

    1993-10-01

    Researchers at the Savannah River Technology Center (SRTC) have developed a class of fiber-optic temperature sensors based upon temperature induced changes in the absorption spectrum of selected materials. For example, a neodymium (Nd) doped glass sensor can be used over a very broad temperature range ({minus}196 to 500{degree}C) and provide good precision and accuracy ({plus_minus}1{degree}C). This type temperature probe is constructed so that light from a fiber optic cable shines through the Nd glass and is reflected onto a second fiber optic cable. Light from this second fiber optic is measured by a diode array spectrophotometer, and the absorption spectrum of the Nd glass used to compute temperature.

  5. Fiber-Optic Temperature Sensor

    NASA Technical Reports Server (NTRS)

    Maram, Jonathan M.

    1987-01-01

    Proposed sensor measures temperatures over wide range, from cryogenic liquids to burning gases. Made in part of optical fibers, sensor lighter in weight than thermocouple and immune to electromagnetic interference. Device does not respond to temperatures elsewhere than at sensing tip. Thermal expansion and contraction of distance between fiber end and mirror alters interference between light reflected from those two surfaces, thereby giving interferometric indication of temperatures.

  6. 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.

  7. Microbend fiber-optic temperature sensor

    DOEpatents

    Weiss, Jonathan D.

    1995-01-01

    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.

  8. Ultrasonic temperature measurements with fiber optic system

    NASA Astrophysics Data System (ADS)

    Bi, Siwen; Wu, Nan; Zhou, Jingcheng; Ma, Tong; Liu, Yuqian; Cao, Chengyu; Wang, Xingwei

    2016-04-01

    Ultrasonic temperature measurements have been developed and widely applied in non-contact temperature tests in many industries. However, using optical fibers to build ultrasound generators are novel. This paper reports this new fiber optic ultrasonic system based on the generator of gold nanoparticles/polydimethylsiloxane (PDMS) composites. The optical acoustic system was designed to test the change of temperature on the aluminum plate and the temperature of the torch in the air. This paper explores the relationship between the ultrasonic transmission and the change of temperature. From the experimental results, the trend of ultrasonic speed was different in the aluminum plate and air with the change of temperature. Since the system can measure the average temperature of the transmission path, it will have significant influence on simulating the temperature distribution.

  9. 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.

  10. Fiber optic temperature sensors for medical applications

    NASA Astrophysics Data System (ADS)

    Schaafsma, David T.; Palmer, Gail; Bechtel, James H.

    2003-07-01

    Recent developments in fiber-optic sensor technology have demonstrated the utility of fiber-optic sensors for both medical and industrial applications. Fiber sensors based on fluorescent decay of rare earth doped materials allow rapid and accurate temperature measurement in challenging environments. Here we review the principles of operation of these sensors with a rare earth doped probe material and demonstrate why this material is an excellent choice for these types of sensors. The decay time technique allows accurate temperature determination from two measurements of the fluorescence intensity at a well-defined time interval. With this method, all instrumental and extraneous environmental effect will cancel, thus providing an accurate temperature measurement. Stability data will be presented for the fiber-optic probes. For medical applications, new breakthroughs in RF ablation technology and electro-surgical procedures are being introduced as alternative, less invasive treatment for removal of small tumors and for removal of plaque within arteries as a preventive treatment that avoids open heart surgery. The availability of small diameter temperature probes (230 microns or 450 microns in diameter) offers a whole new scope to temperature measurement. Accurate and reliable temperature monitoring during any laser treatment procedure or RF ablation at the surgical site is critical. Precise, NIST traceable reliable results are needed to prevent overheating or underheating during treatment. In addition, how interventional catheters are used in hyperthermia studies and the advantages to having flexible cables and multiple sensors are discussed. Preliminary data is given from an animal study where temperature was monitored in a pig during an RF study.

  11. 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.

  12. 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.

  13. Leakage detection using fiber optics distributed temperature monitoring

    NASA Astrophysics Data System (ADS)

    Nikles, Marc; Vogel, Bernhard H.; Briffod, Fabien; Grosswig, Stephan; Sauser, Florian; Luebbecke, Steffen; Bals, Andre; Pfeiffer, Thomas

    2004-07-01

    The monitoring of temperature profiles over long distance by means of optical fibers represents a highly efficient way to perform leakage detection along pipelines, in dams, dykes, or tanks... Different techniques have been developed taking advantages of the fiber geometry and of optical time domain analysis for the localization of the information. Among fiber optics distributed temperature sensing techniques, Brillouin-based systems have demonstrated to have the best potential for applications over distances up to several tens of kilometers. The key features and performances are reviewed in the present article and a 55km pipeline equipped with a fiber optics leakage detection system is presented as a case study.

  14. Portable optical fiber probe for in vivo brain temperature measurements

    PubMed Central

    Musolino, Stefan; Schartner, Erik P.; Tsiminis, Georgios; Salem, Abdallah; Monro, Tanya M.; Hutchinson, Mark R.

    2016-01-01

    This work reports on the development of an optical fiber based probe for in vivo measurements of brain temperature. By utilizing a thin layer of rare-earth doped tellurite glass on the tip of a conventional silica optical fiber a robust probe, suitable for long-term in vivo measurements of temperature can be fabricated. This probe can be interrogated using a portable optical measurement setup, allowing for measurements to be performed outside of standard optical laboratories. PMID:27570698

  15. Portable optical fiber probe for in vivo brain temperature measurements.

    PubMed

    Musolino, Stefan; Schartner, Erik P; Tsiminis, Georgios; Salem, Abdallah; Monro, Tanya M; Hutchinson, Mark R

    2016-08-01

    This work reports on the development of an optical fiber based probe for in vivo measurements of brain temperature. By utilizing a thin layer of rare-earth doped tellurite glass on the tip of a conventional silica optical fiber a robust probe, suitable for long-term in vivo measurements of temperature can be fabricated. This probe can be interrogated using a portable optical measurement setup, allowing for measurements to be performed outside of standard optical laboratories. PMID:27570698

  16. Optical crystal temperature gauge with fiber optic connections

    SciTech Connect

    Sharma, M.M.

    1982-07-01

    An optical temperature gauge uses a semiconductor crystal with a band-edge shift property which is temperature dependent. An external narrow band light source provides optical excitation through a optical fiber and light energy thus passed through the crystal is conveyed by a second optical fiber to a light-to-electric transducers at an external location. The crystal can be located in cryogenic or other systems, to provide remote read-out. The light wavelength is varied (scanned) in a repetitive pattern in source with the instantaneous wavelength passing over the band-edge wavelength during each cycle of the scan. The timing of the crossover is related to the temperature of the crystal by electronic means. Several alternative elements of instrumentation are disclosed. A variation in the basic measurement apparatus is also disclosed, in which the band gap voltage of a light source such as a laser diode is evaluated at the time of band-edge crossover in the crystal and converted to a temperature value. Official Gazette of the U.S. Patent and Trademark Office

  17. Low-temperature hermetic sealing of optical fiber components

    DOEpatents

    Kramer, D.P.

    1996-10-22

    A method for manufacturing low-temperature hermetically sealed optical fiber components is provided. The method comprises the steps of: inserting an optical fiber into a housing, the optical fiber having a glass core, a glass cladding and a protective buffer layer disposed around the core and cladding; heating the housing to a predetermined temperature, the predetermined temperature being below a melting point for the protective buffer layer and above a melting point of a solder; placing the solder in communication with the heated housing to allow the solder to form an eutectic and thereby fill a gap between the interior of the housing and the optical fiber; and cooling the housing to allow the solder to form a hermetic compression seal between the housing and the optical fiber. 5 figs.

  18. Low-temperature hermetic sealing of optical fiber components

    SciTech Connect

    Kramer, D.P.

    1995-12-31

    A method for manufacturing low-temperature hermetically sealed optical fiber components is provided. The method comprises the steps of: inserting an optical fiber into a housing, the optical fiber having a glass core, a glass cladding and a protective buffer layer disposed around the core and cladding; heating the housing to a predetermined temperature, the predetermined temperature being below a melting point for the protective buffer layer and above a melting point of a solder; placing the solder in communication with the heated housing to allow the solder to form an eutectic and thereby fill a gap between the interior of the housing and the optical fiber; and cooling the housing to allow the solder to form a hermetic compression seal between the housing and the optical fiber.

  19. Optical fibers with dual coatings for high-temperature applications

    NASA Astrophysics Data System (ADS)

    Stolov, Andrei A.; Simoff, Debra A.; Lindholm, Eric A.; Ciardiello, Catherine R.

    2010-10-01

    We describe a new optical fiber coating, comprising layers of UV-curable silicone and high-temperature acrylate, with and without hermetic carbon. Optical and mechanical properties of graded index 50/125 μm multimode fibers drawn with the new coating are examined. The new coatings display superior thermal stability in comparison with conventional dual acrylate coatings.

  20. Computational design of an optic fiber temperature sensor

    NASA Astrophysics Data System (ADS)

    Campo Caicedo, Damián Andrés

    2012-06-01

    I will present a computational method for the analysis and design of a temperature sensor based on optical fiber. I will combine symbolic and numerical computations using the following software: Maple, for symbolic computation; Ansys: and Quick-Field for the numerical-graph computation of temperature profiles; Opticfiber for the numerical-graph computation of the electromagnetic modes in the fiber optics. The design strategy is to convert the patterns of temperature in changes of the refractive index of the fiber and the detection of changes in the electro-optical normal modes in the fiber. The proposed method has many advantages for the design of optical fiber sensors nowadays, for temperature measurements as well for other physical variables. We will use many special functions of Mathematical Physics such as the error function, Bessel functions, Kummer functions, Heun functiions, Whittaker functions and Laguerre functions. We will use Maple to make very complex computations with such functions.

  1. Mechanical properties of polyimide coated optical fibers at elevated temperatures

    NASA Astrophysics Data System (ADS)

    Huang, Lei; Dyer, Robert S.; Lago, Ralph J.; Stolov, Andrei A.; Li, Jie

    2016-03-01

    High temperature mechanical strength and reliability of optical fibers have become important subjects as optical fibers are increasingly used for harsher environments. Theories and models of fiber mechanical properties established for traditional telecommunications applications may need to be validated for applications at elevated temperatures. In this paper, we describe the test setup for high temperature tensile strength of fiber and report initial results of dynamic tensile strength of polyimide coated optical fiber at 300 and 350ºC for different heating time intervals. The results are compared with room temperature strength data, data available in the literature, and our earlier work on thermogravimetric analysis (TGA) weight loss of the polyimide coating and the observations on surface morphology at elevated temperatures. Interesting observations are discussed and possible explanations are proposed.

  2. Temperature-independent polymer optical fiber evanescent wave sensor

    PubMed Central

    Zhong, Nianbing; Liao, Qiang; Zhu, Xun; Zhao, Mingfu; Huang, Yun; Chen, Rong

    2015-01-01

    Although the numerous advantages of polymer optical fibers have been exploited in the fields of sensors and telecommunications, such fibers still experience a critical problem: the temperature dependency. Therefore, we explored the temperature-independent operation of a polymer fiber-optic evanescent wave sensor immersed in distilled water. We investigated variations in the surface morphology, deformation trajectory, refractive index, and weight of the fiber-sensing region with varying water temperature. We also examined the spectral transmission and transmitted light intensity of fibers subjected to a heating-cooling treatment. We observed that the light-transmission modes and sensitivity of the sensor were affected by changes in the surface morphology, diameter, and refractive index of the sensing region caused by changes in temperature. The transmitted light intensity of the sensor was maintained at a constant level after five cycles of the heating-cooling treatment, after which the fibers exhibited a smooth surface, low refractive index, and large fiber diameter. Consequently, we utilized the heating-cooling-treated fiber to realize a temperature-independent, U-shaped polymer fiber-optic evanescent wave sensor. The temperature independence was evaluated using glucose solutions in the range of 10 to 70 °C. The fabricated sensor showed significant temperature independence and high degree of consistency in measuring solutions. PMID:26112908

  3. Low-temperature hermetic sealing of optical fiber components

    DOEpatents

    Kramer, Daniel P.

    1996-10-22

    A method for manufacturing low-temperature hermetically sealed optical fi components is provided. The method comprises the steps of: inserting an optical fiber into a housing, the optical fiber having a glass core, a glass cladding and a protective buffer layer disposed around the core and cladding; heating the housing to a predetermined temperature, the predetermined temperature being below a melting point for the protective buffer layer and above a melting point of a solder; placing the solder in communication with the heated housing to allow the solder to form an eutectic and thereby fill a gap between the interior of the housing and the optical fiber; and cooling the housing to allow the solder to form a hermetic compression seal between the housing and the optical fiber.

  4. Optical fiber voltage sensors for broad temperature ranges

    NASA Astrophysics Data System (ADS)

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

    1992-12-01

    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.

  5. 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.

  6. Optical fiber temperature sensors: applications in heat treatments for foods

    NASA Astrophysics Data System (ADS)

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

    2010-10-01

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

  7. Noncontact measurement of high temperature using optical fiber sensors

    NASA Technical Reports Server (NTRS)

    Claus, R. O.

    1990-01-01

    The primary goal of this research program was the investigation and application of noncontact temperature measurement techniques using optical techniques and optical fiber methods. In particular, a pyrometer utilizing an infrared optical light pipe and a multiwavelength filtering approach was designed, revised, and tested. This work was motivated by the need to measure the temperatures of small metallic pellets (approximately 3 mm diameter) in free fall at the Microgravity Materials Processing Drop Tube at NASA Marshall Space Flight Center. In addition, research under this program investigated the adaptation of holography technology to optical fiber sensors, and also examined the use of rare-earth dopants in optical fibers for use in measuring temperature. The pyrometer development effort involved both theoretical analysis and experimental tests. For the analysis, a mathematical model based on radiative transfer principles was derived. Key parameter values representative of the drop tube system, such as particle size, tube diameter and length, and particle temperature, were used to determine an estimate of the radiant flux that will be incident on the face of an optical fiber or light pipe used to collect radiation from the incandescent falling particle. An extension of this work examined the advantage of inclining or tilting the collecting fiber to increase the time that the falling particle remains in the fiber field-of-view. Those results indicate that increases in total power collected of about 15 percent may be realized by tilting the fiber. In order to determine the suitability of alternative light pipes and optical fibers, and experimental set-up for measuring the transmittance and insertion loss of infrared fibers considered for use in the pyrometer was assembled. A zirconium fluoride optical fiber and several bundles of hollow core fiber of varying diameters were tested. A prototype two-color pyrometer was assembled and tested at Virginia Tech, and then

  8. Qualification of Fiber Optic Cables for Martian Extreme Temperature Environments

    NASA Technical Reports Server (NTRS)

    Ramesham, Rajeshuni; Lindensmith, Christian A.; Roberts, William T.; Rainen, Richard A.

    2011-01-01

    Means have been developed for enabling fiber optic cables of the Laser Induced Breakdown Spectrometer instrument to survive ground operations plus the nominal 670 Martian conditions that include Martian summer and winter seasons. The purpose of this development was to validate the use of the rover external fiber optic cabling of ChemCam for space applications under the extreme thermal environments to be encountered during the Mars Science Laboratory (MSL) mission. Flight-representative fiber optic cables were subjected to extreme temperature thermal cycling of the same diurnal depth (or delta T) as expected in flight, but for three times the expected number of in-flight thermal cycles. The survivability of fiber optic cables was tested for 600 cumulative thermal cycles from -130 to +15 C to cover the winter season, and another 1,410 cumulative cycles from -105 to +40 C to cover the summer season. This test satisfies the required 3 times the design margin that is a total of 2,010 thermal cycles (670 x 3). This development test included functional optical transmission tests during the course of the test. Transmission of the fiber optic cables was performed prior to and after 1,288 thermal cycles and 2,010 thermal cycles. No significant changes in transmission were observed on either of the two representative fiber cables subject through the 3X MSL mission life that is 2,010 thermal cycles.

  9. Using a Fiber Loop and Fiber Bragg Grating as a Fiber Optic Sensor to Simultaneously Measure Temperature and Displacement

    PubMed Central

    Chang, Yao-Tang; Yen, Chih-Ta; Wu, Yue-Shiun; Cheng, Hsu-Chih

    2013-01-01

    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. PMID:23681094

  10. 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.

  11. Fiber optic photoelastic pressure sensor for high temperature gases

    NASA Technical Reports Server (NTRS)

    Wesson, Laurence N.; Redner, Alex S.; Baumbick, Robert J.

    1990-01-01

    A novel fiber optic pressure sensor based on the photoelastic effects has been developed for extremely high temperature gases. At temperatures varying from 25 to 650 C, the sensor experiences no change in the peak pressure of the transfer function and only a 10 percent drop in dynamic range. Refinement of the sensor has resulted in an optoelectronic interface and processor software which can calculate pressure values within 1 percent of full scale at any temperature within the full calibrated temperature range.

  12. High-temperature sputtered coatings for optical fiber

    NASA Astrophysics Data System (ADS)

    Rogers, Harvey N.

    1993-02-01

    We have developed a magnetron sputter coating method to continuously coat silica optical fibers with a dual layer coating of Inconel 625 alloy and platinum. The coating process is performed on-line as the fiber is drawn to minimize the rapid strength degradation of the silica due to attack by moisture in the air. Because of the modular design of the sputter equipment, the process is well suited for the deposition of a wide variety of metals and is readily adapted for scale-up. Multimode optical fibers were produced with coatings up to 0.5 microns in thickness consisting of an adhesion layer of Inconel and an outer layer of platinum. The coatings are adherent and remain mechanically intact after thermal cycling between room temperature and 2000 degree(s)F in vacuum. Approximate tensile strengths of 145 to 290 Kpse have been measured. These attributes make this sputter coated fiber a promising candidate for use in high temperature environments.

  13. Effects of Cryogenic Temperatures on LEDs and Optical Fiber

    NASA Technical Reports Server (NTRS)

    Pantel, Erica R.

    2005-01-01

    Light Emitting Diodes (LEDs) may provide a simple, low powered light source for future space missions. However, the effects of cryogenic temperatures on LEDs and optical fibers are largely unknown. Tests were performed on a selection of commercially-available LEDs, with wavelengths varying from 468 nm to 950 nm, as well as "white" LEDs. Dry ice and liquid nitrogen (LN2) were used to bring the LEDs to the desired temperatures. The optical fibers were tested using a specially-machined brass cylinder that would allow the fibers to be cooled slowly and evenly in an LN2 dewer. An optical fiber coupled to a spectrometer was used to acquired spectra of a calibration light source (wavelength range 253-922 nm) at various temperatures. Examination of the LED spectra has shown several different effects, depending on the LED in question. Those with wavelengths above 590 nm tend to show a "blue shift" in their peak wavelength and an increase in intensity. Other LEDs developed secondary or tertiary peaks, or showed no peak shift at all, although all LEDs did show an increase in observed intensity. The optical fiber showed a slight non-uniform decrease in transmission as the temperature cooled to -195 C.

  14. 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.

  15. 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.

  16. High-temperature fiber-optic lever microphone

    NASA Technical Reports Server (NTRS)

    Zuckerwar, Allan J.; Cuomo, Frank W.; Nguyen, Trung D.; Rizzi, Stephen A.; Clevenson, Sherman A.

    1995-01-01

    The design and construction of a fiber-optic lever microphone, capable of operating continuously at temperatures up to 538 C (1000 F) are described. The design is based on the theoretical sensitivities of each of the microphone system components, namely, a cartridge containing a stretched membrane, an optical fiber probe, and an optoelectronic amplifier. Laboratory calibrations include the pistonphone sensitivity and harmonic distortion at ambient temperature, and frequency response, background noise, and optical power transmission at both ambient and elevated temperatures. A field test in the Thermal Acoustic Fatigue Apparatus at Langley Research Center, in which the microphone was subjected to overall sound-pressure levels in the range of 130-160 dB and at temperatures from ambient to 538 C, revealed good agreement with a standard probe microphone.

  17. Optical Fiber Strain Instrumentation for High Temperature Aerospace Structural Monitoring

    NASA Technical Reports Server (NTRS)

    Wang, A.

    2002-01-01

    The objective of the program is the development and laboratory demonstration of sensors based on silica optical fibers for measurement of high temperature strain for aerospace materials evaluations. A complete fiber strain sensor system based on white-light interferometry was designed and implemented. An experiment set-up was constructed to permit testing of strain measurement up to 850 C. The strain is created by bending an alumina cantilever beam to which is the fiber sensor is attached. The strain calibration is provided by the application of known beam deflections. To ensure the high temperature operation capability of the sensor, gold-coated single-mode fiber is used. Moreover, a new method of sensor surface attachment which permits accurate sensor gage length determination is also developed. Excellent results were obtained at temperatures up to 800-850 C.

  18. Development of a 2-Channel Embedded Infrared Fiber-Optic Temperature Sensor Using Silver Halide Optical Fibers

    PubMed Central

    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. PMID:22163711

  19. Liquid Seal for Temperature Sensing with Fiber-Optic Refractometers

    PubMed Central

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

    2014-01-01

    Liquid sealing is an effective method to convert a fiber-optic refractometer into a simple and highly sensitive temperature sensor. A refractometer based on the thin-core fiber modal interferometer is sealed in a capillary tube filled with Cargille oil. Due to the thermo-optic effect of the sealing liquid, the high refractive-index sensitivity refractometer is subsequently sensitive to the ambient temperature. It is found that the liquid-sealed sensor produces a highest sensitivity of −2.30 nm/°C, which is over 250 times higher than its intrinsic sensitivity before sealing and significantly higher than that of a grating-based fiber sensors. The sensing mechanisms, including the incidental temperature-induced strain effect, are analyzed in detail both theoretically and experimentally. The liquid sealing technique is easy and low cost, and makes the sensor robust and insensitive to the surrounding refractive index. It can be applied to other fiber-optic refractometers for temperature sensing. PMID:25123468

  20. Fiber optic temperature profiling for thermal protection heat shields

    NASA Astrophysics Data System (ADS)

    Black, Richard J.; Costa, Joannes M.; Moslehi, Behzad; Zarnescu, Livia; Hackney, Drew; Peters, Kara

    2014-04-01

    Reliable Thermal Protection System (TPS) sensors are needed to achieve better designs for spacecraft (probe) heatshields for missions requiring atmospheric aero-capture or entry/reentry. In particular, they will allow both reduced risk and heat-shield mass minimization, which will facilitate more missions and allow increased payloads and returns. For thermal measurements, Intelligent Fiber Optic Systems Corporation (IFOS) is providing a temperature monitoring system involving innovative lightweight, EMI-immune, high-temperature resistant Fiber Bragg Grating (FBG) sensors with a thermal mass near that of TPS materials together with fast FBG sensor interrogation. The IFOS fiber optic sensing technology is highly sensitive and accurate. It is also low-cost and lends itself to high-volume production. Multiple sensing FBGs can be fabricated as arrays on a single fiber for simplified design and reduced cost. In this paper, we provide experimental results to demonstrate the temperature monitoring system using multi-sensor FBG arrays embedded in small-size Super-Light Ablator (SLA) coupon, which was thermally loaded to temperatures in the vicinity of the SLA charring temperature. In addition, a high temperature FBG array was fabricated and tested for 1000°C operation.

  1. Multifunction medical endoscope system with optical fiber temperature sensor

    NASA Astrophysics Data System (ADS)

    He, Zhengquan; Zhou, Libin; Luo, Baoke; Hu, Baowen; Du, Xinchao; Li, Yulin

    2014-09-01

    Thermal therapy (or hyperthermia) is one of the effective operations for tumor treating and curing. As tumor tissues are more susceptible to heat than normal tissues, in thermal therapy operations, temperature on operation area is a crucial parameter for optimal treating. When the temperature is too low, the tumor tissues cannot be killed; otherwise, the temperature is too high, the operation may damage normal tissues around the tumor. During thermal therapy operation, the heating power is normally supplied by high-frequency EM field, so traditional temperature sensors, such as thermal couples, thermistors, cannot work stably due to EM interference. We present a multi-function endoscope optical fiber temperature sensor system. With this sensor setup based on principle of fluorescence life time, the temperature on operation point is detected in real time. Furthermore, a build-in endoscope centers in the fiber sensor, thus the operation area can be viewed or imaged directly during the operation. This design can navigate the operation, particularly for in vivo operations. The temperature range of the sensor system is 30°C-150°C, the accuracy can achieve to 0.2°C. The imaging fiber buddle is constituted of more than 50k fibers. As the sensor probe is very thin (around 4 mm in diameter), it can also be assembled inside the radiofrequency operation knife. With the presented sensor system in clinic operation physicians can check the temperature in the operation point and view the operation area at the same time.

  2. Effects of Temperature and X-rays on Plastic Scintillating Fiber and Infrared Optical Fiber

    PubMed Central

    Lee, Bongsoo; Shin, Sang Hun; Jang, Kyoung Won; Yoo, Wook Jae

    2015-01-01

    In this study, we have studied the effects of temperature and X-ray energy variations on the light output signals from two different fiber-optic sensors, a fiber-optic dosimeter (FOD) based on a BCF-12 as a plastic scintillating fiber (PSF) and a fiber-optic thermometer (FOT) using a silver halide optical fiber as an infrared optical fiber (IR fiber). During X-ray beam irradiation, the scintillating light and IR signals were measured simultaneously using a dosimeter probe of the FOD and a thermometer probe of the FOT. The probes were placed in a beaker with water on the center of a hotplate, under variation of the tube potential of a digital radiography system or the temperature of the water in the beaker. From the experimental results, in the case of the PSF, the scintillator light output at the given tube potential decreased as the temperature increased in the temperature range from 25 to 60 °C. We demonstrated that commonly used BCF-12 has a significant temperature dependence of −0.263 ± 0.028%/°C in the clinical temperature range. Next, in the case of the IR fiber, the intensity of the IR signal was almost uniform at each temperature regardless of the tube potential range from 50 to 150 kVp. Therefore, we also demonstrated that the X-ray beam with an energy range used in diagnostic radiology does not affect the IR signals transmitted via a silver halide optical fiber. PMID:25970257

  3. Effects of Temperature and X-rays on Plastic Scintillating Fiber and Infrared Optical Fiber.

    PubMed

    Lee, Bongsoo; Shin, Sang Hun; Jang, Kyoung Won; Yoo, Wook Jae

    2015-01-01

    In this study, we have studied the effects of temperature and X-ray energy variations on the light output signals from two different fiber-optic sensors, a fiber-optic dosimeter (FOD) based on a BCF-12 as a plastic scintillating fiber (PSF) and a fiber-optic thermometer (FOT) using a silver halide optical fiber as an infrared optical fiber (IR fiber). During X-ray beam irradiation, the scintillating light and IR signals were measured simultaneously using a dosimeter probe of the FOD and a thermometer probe of the FOT. The probes were placed in a beaker with water on the center of a hotplate, under variation of the tube potential of a digital radiography system or the temperature of the water in the beaker. From the experimental results, in the case of the PSF, the scintillator light output at the given tube potential decreased as the temperature increased in the temperature range from 25 to 60 °C. We demonstrated that commonly used BCF-12 has a significant temperature dependence of -0.263 ± 0.028%/°C in the clinical temperature range. Next, in the case of the IR fiber, the intensity of the IR signal was almost uniform at each temperature regardless of the tube potential range from 50 to 150 kVp. Therefore, we also demonstrated that the X-ray beam with an energy range used in diagnostic radiology does not affect the IR signals transmitted via a silver halide optical fiber. PMID:25970257

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

    NASA Astrophysics Data System (ADS)

    Hawn, David P.

    Distributed measurements made with fiber optic instrumentation have the potential to revolutionize data collection for facility monitoring and process control in industrial environments. Dozens of sensors etched into a single optical fiber can be used to instrument equipment and structures so that dozens of spatially distributed temperature measurements, for example, can be made quickly using one optical fiber. Optically based sensors are commercially available to measure temperature, strain, and other physical quantities that can be related to strain, such as pressure and acceleration. Other commercially available technology eliminates the need to etch discrete sensors into an optical fiber and allows temperature measurements to be made along the length of an ordinary silica fiber. Distributed sensing with optical instrumentation is commonly used in the petroleum industry to measure the temperature and pressure profiles in down hole applications. The U.S. Department of Energy is interested in extending the distributed sensing capabilities of optical instrumentation to high temperature reactor radiation environments. For this technology extension to be possible, the survivability of silica optical fibers needed to be determined in this environment. In this work the optical attenuation added to silica optical fiber exposed simultaneously to reactor radiation and temperatures to 1000°C was experimentally determined. Optical transmission measurements were made in-situ from 400nm-2300nm. For easy visualization, all of the results generated in this work were processed into movies that are available publicly [1]. In this investigation, silica optical fibers were shown to survive optically and mechanically in a reactor radiation environment to 1000°C. For the combined high temperature reactor irradiation experiments completed in this investigation, the maximum attenuation increase in the low-OH optical fibers was around 0.5db/m at 1550nm and 0.6dB/m at 1300nm. The

  5. Optically heated fiber Bragg grating in active fibers for low temperature sensing application

    NASA Astrophysics Data System (ADS)

    Qi, Lin; Jin, Long; Guan, Bai-Ou

    2013-09-01

    Optically heated fiber Bragg gratings due to the absorption over the fiber core in rare-earth doped fibers are experimentally demonstrated. Bragg wavelength variations with pump power are measured for different fibers. We found that the Er/Yb-codoped fiber presents the strongest thermal effect, due to the high absorption. A maximum wavelength shift of 1.34 nm can be obtained when the 980 nm pump power is 358 mW under room temperature, suggesting the fiber is heated up to over 100 °C. Furthermore, the thermal effect is enhanced by pumping the surrounding air to close to vacuum. A wavelength shift of 1.69 nm is attained, due to the weakened ability of heat transfer at the silica-air interface. The optical heating presents a very short response time and can found applications in low temperature circumstances.

  6. A fiber optic temperature sensor for aerospace applications

    NASA Astrophysics Data System (ADS)

    Jensen, Stephen C.; Tilstra, Shelle D.; Barnabo, Geoffrey A.; Thomas, David C.; Phillips, Richard W.

    1991-02-01

    A fiber-optic temperature sensor has been developed for aerospace applications on the basis of the time rate of decay (TRD) principle, with a view to an operational temperature range of -60 to 350 C. This TRD system has completed qualification testing and will then undergo flight tests. Attention is presently given to the design and performance of four low temperature sensors that are subelements of the larger sensor system; in order to convert analog signals into over/under temperature indications, simple comparators are implemented in software.

  7. Thin-film fiber optic hydrogen and temperature sensor system

    DOEpatents

    Nave, S.E.

    1998-07-21

    The invention discloses a sensor probe device for monitoring of hydrogen gas concentrations and temperatures by the same sensor probe. The sensor probe is constructed using thin-film deposition methods for the placement of a multitude of layers of materials sensitive to hydrogen concentrations and temperature on the end of a light transparent lens located within the sensor probe. The end of the lens within the sensor probe contains a lens containing a layer of hydrogen permeable material which excludes other reactive gases, a layer of reflective metal material that forms a metal hydride upon absorbing hydrogen, and a layer of semi-conducting solid that is transparent above a temperature dependent minimum wavelength for temperature detection. The three layers of materials are located at the distal end of the lens located within the sensor probe. The lens focuses light generated by broad-band light generator and connected by fiber-optics to the sensor probe, onto a reflective metal material layer, which passes through the semi-conducting solid layer, onto two optical fibers located at the base of the sensor probe. The reflected light is transmitted over fiber optic cables to a spectrometer and system controller. The absence of electrical signals and electrical wires in the sensor probe provides for an elimination of the potential for spark sources when monitoring in hydrogen rich environments, and provides a sensor free from electrical interferences. 3 figs.

  8. Optical Fiber High Temperature Sensor Instrumentation for Energy Intensive Industries

    SciTech Connect

    Cooper, Kristie L.; Wang, Anbo; Pickrell, Gary R.

    2006-11-14

    This report summarizes technical progress during the program “Optical Fiber High Temperature Sensor Instrumentation for Energy Intensive Industries”, performed by the Center for Photonics Technology of the Bradley Department of Electrical and Computer Engineering at Virginia Tech. The objective of this program was to use technology recently invented at Virginia Tech to develop and demonstrate the application of self-calibrating optical fiber temperature and pressure sensors to several key energy-intensive industries where conventional, commercially available sensors exhibit greatly abbreviated lifetimes due primarily to environmental degradation. A number of significant technologies were developed under this program, including • a laser bonded silica high temperature fiber sensor with a high temperature capability up to 700°C and a frequency response up to 150 kHz, • the world’s smallest fiber Fabry-Perot high temperature pressure sensor (125 x 20 μm) with 700°C capability, • UV-induced intrinsic Fabry-Perot interferometric sensors for distributed measurement, • a single crystal sapphire fiber-based sensor with a temperature capability up to 1600°C. These technologies have been well demonstrated and laboratory tested. Our work plan included conducting major field tests of these technologies at EPRI, Corning, Pratt & Whitney, and Global Energy; field validation of the technology is critical to ensuring its usefulness to U.S. industries. Unfortunately, due to budget cuts, DOE was unable to follow through with its funding commitment to support Energy Efficiency Science Initiative projects and this final phase was eliminated.

  9. AUV-portable temperature-compensating fiber optic hydrophone

    NASA Astrophysics Data System (ADS)

    Saxena, Indu Fiesler; Guzman, Narciso; Hui, Kaleonui J.; Pflanze, Stephen

    2011-06-01

    Passive acoustic monitoring hydrophones with low power consumption for autonomous underwater vehicles (AUVs) are desirable for long term unmanned monitoring of ocean acoustics including marine mammal acoustics as well as those due to human activity. Fiber-optic hydrophones offer wider bandwidth and high sensitivity alternatives to conventional piezoelectric transducer (PZT) devices. Deployment on board AUVs requires operation under a wide range of temperature and pressure conditions that change with depth and location, hence, maintaining the sensitivity and reliability over the operating range is crucial. A read-out mechanism for a resonant hydrophone using a fiber Bragg grating (FBG) transducer is described. The read-out uses a temperature tuned DFB laser diode to compensate for FBG changes with temperature and depth, enabling operation over a wide temperature range. Its compact footprint and battery-powered readout system operation enables portability on AUVs.

  10. 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.

  11. High-temperature fiber optic cubic-zirconia pressure sensor

    NASA Astrophysics Data System (ADS)

    Peng, Wei; Pickrell, Gary R.; Wang, Anbo

    2005-12-01

    There is a critical need for pressure sensors that can operate reliably at high temperatures in many industrial segments such as in the combustion section of gas turbine engines for both transportation and power generation, coal gasifiers, coal fired boilers, etc. Optical-based sensors are particularly attractive for the measurement of a wide variety of physical and chemical parameters in high-temperature and high-pressure industrial environments due to their small size and immunity to electromagnetic interference. A fiber optic pressure sensor utilizing single-crystal cubic zirconia as the sensing element is reported. The pressure response of this sensor has been measured at temperatures up to 1000 °C. Additional experimental results show that cubic zirconia could be used for pressure sensing at temperatures over 1000 °C. This study demonstrates the feasibility of using a novel cubic-zirconia sensor for pressure measurement at high temperatures.

  12. Fiber-optic distributed temperature sensing of alpine snowpacks

    NASA Astrophysics Data System (ADS)

    Huwald, H.; Mutzner, R.; Williams, S. R.; Higgins, C. W.; Nolin, A. W.; Drake, S. A.; Selker, J. S.; Parlange, M. B.

    2011-12-01

    Small-scale surface topography and variations in snow density and in the snowpack matrix influence the snow temperature, a key variable for various heat flux components of the surface energy balance. Thus detailed knowledge on the spatial distribution and temporal evolution is crucial to quantify horizontal heterogeneity in the heat fluxes at the snow surface. We present measurements of small-scale temperature variations in alpine snow packs using fiber-optic distributed temperature sensing (DTS) together with traditional sensors such as thermocouples and thermistors. Almost a kilometer of fiber-optic cable was installed in the snow at Plaine Morte and Jungfraufirn glacier in the Swiss Alps, to obtain distributed information on snow temperature. The sensor cables were deployed in various configurations such as a fence-like structure anchored in the snowpack providing 2D snow temperature slices as snow accumulated and covered the fence, or a sensor tube with 4mm vertical resolution for high-resolution profiles. Measurements were taken at intervals of 5 minutes, with a spatial resolution of 1m and accuracy better than 0.1C. Besides the diurnal cycle, temperature data show some spatial variability along the transect. Subsurface heat fluxes were computed based on the Fourier heat equation using snow temperature and snow depth data, and an effective thermal conductivity of the snow derived from density measurements. Cable exposure to shortwave radiation near the surface and snow accumulation/compaction caused problems such as temperature overestimation and sagging of the cable between fence poles, respectively.

  13. Fiber-Optic Strain and Temperature Monitoring System for DUSEL

    NASA Astrophysics Data System (ADS)

    Wang, H. F.; Maclaughlin, M.; Fratta, D.; Murdoch, L. C.

    2009-12-01

    The opportunity to understand the response of rock masses to stresses deep within the earth's crust as a function of spatial and temporal scale is at the center of the geomechanics research program proposed for DUSEL. Within the 10-km3 volume of the former Homestake mine, deformations are expected from earth tides, effective stress changes caused by mine dewatering, seasonal water table changes, and new excavations as well as from long-term creep of drifts and shafts. Data from a whole-mine deformation monitoring and measurement system are integral to calibrating a mine-scale, mechanical and hydrological finite-element model of laboratory and detector space. A synergistic objective of a long-term, state-of-the-art monitoring system is to ensure shaft, tunnel, and cavern stability as well as occupant safety. Fiber-optic sensors are highly stable over long periods of time and they can be daisy-chained to significantly simplify the logistics of acquiring data from dozens of sensors. Temperature measurements over large spatial scales in fluid-saturated boreholes can delineate fluid-flow paths and can be deployed as a secondary monitoring system for ventilation and anomalous air temperatures. Two types of fiber-optic sensors are available: distributed strain and temperature (DST) and Fiber Bragg Grating (FBG). DST sensors can be installed over kilometers of distance with measurement resolutions of 1-to-10 microstrains and 0.1°C over intervals of 1-to-2 meters. FBG strain gages and displacement transducers function the same as their electrical counterparts, save for the underlying physics in that displacements are measured as a shift in the spacing of a Bragg grating embedded into the optical fiber. These systems are highly scalable as more than 50,000 points of temperature and strain measurements can be collected from a single fiber-optic cable. Other fiber-based sensors, e.g., acceleration, air pressure, and gases, are also available and can become part of a fiber

  14. Flight Tests on a Fiber Optic Temperature Sensor

    NASA Technical Reports Server (NTRS)

    Tuma, Margaret L.; Sawatari, Takeo; Lin, Yuping; Elam, Kristie A.

    1998-01-01

    For aircraft engine control, one key parameter to detect on an airplane is the exhaust gas temperature (EGT). Presently, thermocouples are used to perform this measurement. These electrical sensors perform adequately; however, fully utilizing the benefits of optical sensors requires replacing electrical architectures with optical architectures. Part of this requires replacing electrical sensors with optical sensors, such as the EGT sensor chosen for these tests. The objective of the development and testing of this prototype sensor system was to determine the feasibility of operating an optical sensor in a hostile aircraft environment. The fiber optic sensor system was developed to measure temperatures from 20C to 600C in an aircraft environment and was utilized to monitor the EGT of an OV-10D aircraft engine. The sensor has successfully flown over 50 hours and proven to be immune to surface deterioration of the optical element (located inside the sensor head) and able to withstand and operate in normal and sustained severe flight conditions where forces on the airplane exceeded 4 g's. Potential commercial uses for this sensor include monitoring temperature for aeropropulsion system control, military vehicle and naval engine control, conventional and nuclear power plant monitoring and industrial plan monitoring where EMI issues are critical.

  15. Optical fiber distributed temperature sensor in cardiological surgeries

    NASA Astrophysics Data System (ADS)

    Skapa, Jan; Látal, Jan; Penhaker, Marek; Koudelka, Petr; Hancek, František; Vasinek, Vladimír

    2010-04-01

    In those days a lot of cardiological surgeries is made every day. It is a matter of very significant importance keeping the temperature of the hearth low during the surgery because it decides whether the cells of the muscle will die or not. The hearth is cooled by the ice placed around the hearth muscle during the surgery and cooling liquid is injected into the hearth also. In these days the temperature is measured only in some points of the hearth using sensors based on the pH measurements. This article describes new method for measurement of temperature of the hearth muscle during the cardiological surgery. We use a multimode optical fiber and distributed temperature sensor (DTS) based on the stimulated Raman scattering in temperature measurements. This principle allows us to measure the temperature and to determine where the temperature changes during the surgery. Resolution in the temperature is about 0.1 degrees of Celsius. Resolution in length is about 1 meter. The resolution in length implies that the fiber must be wound to ensure the spatial resolution about 5 by 5 centimeters.

  16. High-temperature sapphire optical sensor fiber coatings

    NASA Astrophysics Data System (ADS)

    Desu, Seshu B.; Claus, Richard O.; Raheem, Ruby; Murphy, Kent A.

    1990-10-01

    the filter. These modes may be attributed to a number of material degradation mechanisms, such as thermal shock, oxidation corrosion of the material, mechanical loads, or phase changes in the filter material. Development of high temperature optical fiber (sapphire) sensors embedded in the CXF filters would be very valuable for both monitoring the integrity of the filter during its use and understanding the mechanisms of degradation such that durable filter development will be facilitated. Since the filter operating environment is very harsh, the high temperature sapphire optical fibers need to be protected and for some sensing techniques the fiber must also be coated with low refractive index film (cladding). The objective of the present study is to identify materials and develop process technologies for the application of claddings and protective coatings that are stable and compatible with sapphire fibers at both high temperatures and pressures.

  17. Thin-film fiber optic hydrogen and temperature sensor system

    DOEpatents

    Nave, Stanley E.

    1998-01-01

    The invention discloses a sensor probe device for monitoring of hydrogen gas concentrations and temperatures by the same sensor probe. The sensor probe is constructed using thin-film deposition methods for the placement of a multitude of layers of materials sensitive to hydrogen concentrations and temperature on the end of a light transparent lens located within the sensor probe. The end of the lens within the sensor probe contains a lens containing a layer of hydrogen permeable material which excludes other reactive gases, a layer of reflective metal material that forms a metal hydride upon absorbing hydrogen, and a layer of semi-conducting solid that is transparent above a temperature dependent minimum wavelength for temperature detection. The three layers of materials are located at the distal end of the lens located within the sensor probe. The lens focuses light generated by broad-band light generator and connected by fiber-optics to the sensor probe, onto a reflective metal material layer, which passes through the semi-conducting solid layer, onto two optical fibers located at the base of the sensor probe. The reflected light is transmitted over fiberoptic cables to a spectrometer and system controller. The absence of electrical signals and electrical wires in the sensor probe provides for an elimination of the potential for spark sources when monitoring in hydrogen rich environments, and provides a sensor free from electrical interferences.

  18. Fiber-Optic Surface Temperature Sensor Based on Modal Interference.

    PubMed

    Musin, Frédéric; Mégret, Patrice; Wuilpart, Marc

    2016-01-01

    Spatially-integrated surface temperature sensing is highly useful when it comes to controlling processes, detecting hazardous conditions or monitoring the health and safety of equipment and people. Fiber-optic sensing based on modal interference has shown great sensitivity to temperature variation, by means of cost-effective image-processing of few-mode interference patterns. New developments in the field of sensor configuration, as described in this paper, include an innovative cooling and heating phase discrimination functionality and more precise measurements, based entirely on the image processing of interference patterns. The proposed technique was applied to the measurement of the integrated surface temperature of a hollow cylinder and compared with a conventional measurement system, consisting of an infrared camera and precision temperature probe. As a result, the optical technique is in line with the reference system. Compared with conventional surface temperature probes, the optical technique has the following advantages: low heat capacity temperature measurement errors, easier spatial deployment, and replacement of multiple angle infrared camera shooting and the continuous monitoring of surfaces that are not visually accessible. PMID:27483271

  19. 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.

  20. Fiber optics in adverse environments

    SciTech Connect

    Lyous, P.B.

    1982-01-01

    Radiation effects in optical fibers are considered, taking into account recent progress in the investigation of radiation resistant optical fibers, radiation damage in optical fibers, radiation-induced transient absorption in optical fibers, X-ray-induced transient attenuation at low temperatures in polymer clad silica (PCS) fibers, optical fiber composition and radiation hardness, the response of irradiated optical waveguides at low temperatures, and the effect of ionizing radiation on fiber-optic waveguides. Other topics explored are related to environmental effects on components of fiber optic systems, and radiation detection systems using optical fibers. Fiber optic systems in adverse environments are also discussed, giving attention to the survivability of Army fiber optics systems, space application of fiber optics systems, fiber optic wavelength multiplexing for civil aviation applications, a new fiber optic data bus topology, fiber optics for aircraft engine/inlet control, and application of fiber optics in high voltage substations.

  1. Fiber Optic Distributed Temperature Sensing of Recharge Basin Percolation Dynamics

    NASA Astrophysics Data System (ADS)

    Becker, M.; Allen, E. M.; Hutchinson, A.

    2014-12-01

    Infiltration (spreading) basins are a central component of managed aquifer and recovery operations around the world. The concept is simple. Water is percolated into an aquifer where it can be withdrawn at a later date. However, managing infiltration basins can be complicated by entrapped air in sediments, strata of low permeability, clogging of the recharge surface, and biological growth, among other factors. Understanding the dynamics of percolation in light of these complicating factors provides a basis for making management decisions that increase recharge efficiency. As an aid to understanding percolation dynamics, fiber optic distribute temperature sensing (DTS) was used to track heat as a tracer of water movement in an infiltration basin. The diurnal variation of temperature in the basin was sensed at depth. The time lag between the oscillating temperature signal at the surface and at depth indicated the velocity of water percolation. DTS fiber optic cables were installed horizontally along the basin and vertically in boreholes to measure percolation behavior. The horizontal cable was installed in trenches at 0.3 and 1 m depth, and the vertical cable was installed using direct push technology. The vertical cable was tightly wound to produce a factor of 10 increase in spatial resolution of temperature measurements. Temperature was thus measured every meter across the basin and every 10 cm to a depth of 10 m. Data from the trenched cable suggested homogeneous percolation across the basin, but infiltration rates were a function of stage indicating non-ideal percolation. Vertical temperature monitoring showed significant lateral flow in sediments underlying the basin both during saturation and operation of the basin. Deflections in the vertical temperature profile corresponded with fine grained layers identified in core samples indicating a transient perched water table condition. The three-dimensional flow in this relatively homogenous surficial geology calls

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

    SciTech Connect

    Pheron, X.; Ouerdane, Y.; Delepine-Lesoille, S.; Boukenter, A.; Bertrand, J.

    2011-07-01

    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)

  3. Optical Bragg grating sensor fibers for ultra-high temperature applications

    NASA Astrophysics Data System (ADS)

    Bartelt, Hartmut; Elsmann, Tino; Habisreuther, Tobias; Schuster, Kay; Rothhardt, Manfred

    2015-07-01

    Sapphire based optical fibers provide an attractive basis for ultra-high temperature stable optical sensor elements. Fiber Bragg gratings can be inscribed in such fibers by means of femtosecond-laser pulses with a wavelength of 400 nm in combination with a two-beam phase mask interferometer. We have investigated crystalline optical fibers as well as structured sapphire-derived all glass optical fibers with aluminum content in the core of up to 50 mol%. The reflection properties, the index modulation and the attenuation effects will be discussed. Results concerning the temperature and strain sensitivity for use as sensor elements at high temperatures will be presented.

  4. Integrated optic current transducers incorporating photonic crystal fiber for reduced temperature dependence.

    PubMed

    Chu, Woo-Sung; Kim, Sung-Moon; Oh, Min-Cheol

    2015-08-24

    Optical current transducers (OCT) are indispensable for accurate monitoring of large electrical currents in an environment suffering from severe electromagnetic interference. Temperature dependence of OCTs caused by its components, such as wave plates and optical fibers, should be reduced to allow temperature-independent operation. A photonic crystal fiber with a structural optical birefringence was incorporated instead of a PM fiber, and a spun PM fiber was introduced to overcome the temperature-dependent linear birefringence of sensing fiber coil. Moreover, an integrated optic device that provides higher stability than fiber-optics was employed to control the polarization and detect the phase of the sensed optical signal. The proposed OCT exhibited much lower temperature dependence than that from a previous study. The OCT satisfied the 0.5 accuracy class (IIEC 60044-8) and had a temperature dependence less than ± 1% for a temperature range of 25 to 78 °C. PMID:26368249

  5. Soil temperature variability in complex terrain measured using fiber-optic distributed temperature sensing

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Soil temperature (Ts) exerts critical controls on hydrologic and biogeochemical processes but magnitude and nature of Ts variability in a landscape setting are rarely documented. Fiber optic distributed temperature sensing systems (FO-DTS) potentially measure Ts at high density over a large extent. ...

  6. Interferometric fiber optic temperature sensor using a low-coherence light source

    NASA Astrophysics Data System (ADS)

    Lee, Chung E.; Taylor, Henry F.

    1990-12-01

    An interferometric fiber optic sensor employing a light emitting diode (LED) as the optical source and two fiber Fabry-Perot interferometers (FFPI) which were fabricated in continuous length of a single-mode silica fiber is analyzed. The performance as a temperature sensor is demonstrated and the predicted behavior is confirmed.

  7. 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

    A DC magnetron sputtering system has been used to actively coat optical fibers with hermetic metal coatings during the fiber draw process. Thin films of Inconel 625 have been deposited on optical fibers and annealed in air at 2000 F. Scanning electron microscopy and Auger electron microscopy have been used to investigate the morphology and composition of the films prior to and following thermal cycling. Issues to be addressed include film adhesion, other coating materials, and a discussion of additional applications for this novel technology.

  8. Effect of soil temperature on optical frequency transfer through unidirectional dense-wavelength-division-multiplexing fiber-optic links.

    PubMed

    Pinkert, T J; Böll, O; Willmann, L; Jansen, G S M; Dijck, E A; Groeneveld, B G H M; Smets, R; Bosveld, F C; Ubachs, W; Jungmann, K; Eikema, K S E; Koelemeij, J C J

    2015-02-01

    Results of optical frequency transfer over a carrier-grade dense-wavelength-division-multiplexing (DWDM) optical fiber network are presented. The relation between soil temperature changes on a buried optical fiber and frequency changes of an optical carrier through the fiber is modeled. Soil temperatures, measured at various depths by the Royal Netherlands Meteorology Institute (KNMI) are compared with observed frequency variations through this model. A comparison of a nine-day record of optical frequency measurements through the 2×298  km fiber link with soil temperature data shows qualitative agreement. A soil temperature model is used to predict the link stability over longer periods (days-months-years). We show that optical frequency dissemination is sufficiently stable to distribute and compare, e.g., rubidium frequency standards over standard DWDM optical fiber networks using unidirectional fibers. PMID:25967781

  9. Distributed strain and temperature measurement of a beam using fiber optic BOTDA sensor

    NASA Astrophysics Data System (ADS)

    Kwon, Il-Bum; Kim, Chi-Yeop; Choi, Man-Yong

    2003-08-01

    In order to do continuous health monitoring of large structures, it is necessary that the distributed sensing of strain and temperature of the structures are to be measured. So, we present the strain and temperature measurement distributed on a beam using fiber optic BOTDA(Brillouin Optical Time Domain Analysis) sensor. Fiber optic BOTDA sensor has good performance of strain measurement. However, the signal of fiber optic BOTDA sensor is influenced by strain and temperature. Therefore, we applied an optical fiber on the beam as follows: one part of the fiber, which is sensitive the strain and the temperature, is bonded on the surface of the beam and another part of the fiber, which is only sensitive to the temperature, is located at the same position of the strain sensing fiber. Therefore, the strains can be determined from the strain sensing fiber with compensating the temperature from the temperature sensing fiber. These measured strains were compared with the strains from electrical strain gages. After temperature compensation, it was concluded that the strains from fiber optic BOTDA sensor had good agreements with those values of the conventional strain gages.

  10. GFOC Project results: High Temperature / High Pressure, Hydrogen Tolerant Optical Fiber

    SciTech Connect

    E. Burov; A. Pastouret; E. Aldea; B. Overton; F. Gooijer; A. Bergonzo

    2012-02-12

    Tests results are given for exposure of multimode optical fiber to high temperatures (300 deg. C) and high partial pressure (15 bar) hydrogen. These results demonstrate that fluorine down doped optical fibers are much more hydrogen tolerant than traditional germanium doped multimode optical fibers. Also demonstrated is the similar hydrogen tolerance of carbon coated and non-carbon coated fibers. Model for reversible H2 impact in fiber versus T{sup o}C and H2 pressure is given. These results have significant impact for the longevity of use for distributed temperature sensing applications in harsh environments such as geothermal wells.

  11. Fiber Optic High Temperature Sensors for Re-Entry Vehicles

    NASA Astrophysics Data System (ADS)

    Haddad, E.; Kruzelecky, R.; Zou, J.; Wong, B.; Jamroz, W.; Sayeed, F.; Muylaert, J.-M.; McKenzie, I.

    2009-01-01

    MPB, within an ESA contract, is developing high temperature Fiber sensors (up to 1100°C) for re- ntry experiments, with direct application to the Thermo Protection Surface (TPS) of SHEFEX II. It addresses the challenges of obtaining high reflectivity FBG sensors, and integrating the fiber sensors within the selected TPS host material (C/SiC). Feasibility was demonstrated using free fiber sensors that showed the formation of the Chemical Composition Grating (CCG), with 80 % reflection at temperatures >750°C. The CCG grating was stable at high temperature (1000°C) for more than 50 hours, as well as after cycling between room temperature and 1000°C, with better than 0.5 % temperature accuracy (FBG central wavelength). Small FBG sensor packages were prepared and attached to C/SiC tiles. The calibration of the packaged fibers showed similar response to temperature as the free fiber sensor. The fiber sensor package was designed to maximize contact with the C/SiC surface to provide fast response to transients. Three- imension modeling with Ansys finite element analysis shows a time constant of 15-20 ms to reach 1200°C. A modular design will be implemented where a dedicated fiber line with 3 sensors and its own connector is used for each C/SiC tile. Small coupons of packaged sensors attached to C/SiC tiles will be tested in a re-entry environment at Von Karman Institute (Belgium) In a recently completed project with ESA, MPB developed and ground qualified a fiber sensor network, the "Fiber Sensor Demonstrator", that was successfully integrated as a payload with ESA's Proba-2. The system includes a central interrogation system that can be used to measure multiple parameters including a high temperature sensor for the Proba-2 thruster (up to 500°C).

  12. Measuring artificial recharge with fiber optic distributed temperature sensing.

    PubMed

    Becker, Matthew W; Bauer, Brian; Hutchinson, Adam

    2013-01-01

    Heat was used as a tracer to measure infiltration rates from a recharge basin. The propagation of diurnal oscillation of surface water temperature into the basin bed was monitored along a transect using Fiber Optic Distributed Temperature Sensing (FODTS). The propagation rate was related to downward specific discharge using standard theory of heat advection and dispersion in saturated porous media. An estimate of the temporal variation of heat propagation was achieved using a wavelet transform to find the phase lag between the surface temperature diurnal oscillation and the correlated oscillation at 0.33 and 0.98 m below the bed surface. The wavelet results compared well to a constant velocity model of thermal advection and dispersion during periods of relatively constant discharge rates. The apparent dispersion of heat was found to be due primarily to hydrodynamic mechanisms rather than thermal diffusion. Specific discharge estimates using the FODTS technique also compared well to water balance estimates over a four month period, although there were occasional deviations that have yet to be adequately explained. The FODTS technique is superior to water balance in that it produces estimates of infiltration rate every meter along the cable transect, every half hour. These high resolution measurements highlighted areas of low infiltration and demonstrated the degradation of basin efficiency due to source waters of high suspended solids. FODTS monitoring promises to be a useful tool for diagnosing basin performance in an era of increasing groundwater demand. PMID:23110559

  13. Fiber - Optic Devices as Temperature Sensors for Temperature Measurements in AC Magnetic Fields

    NASA Astrophysics Data System (ADS)

    Rablau, Corneliu; Lafrance, Joseph; Sala, Anca

    2007-10-01

    We report on the investigation of several fiber-optic devices as potential sensors for temperature measurements in AC magnetic fields. Common temperature sensors, such as thermocouples, thermistors or diodes, will create random and/or systematic errors when placed in a magnetic field. A DC magnetic field is susceptible to create a systematic offset to the measurement, while in an AC magnetic field of variable frequency random errors which cannot be corrected for can also be introduced. Fiber-Bragg-gratings and thin film filters have an inherent temperature dependence. Detrimental for their primary applications, the same dependence allows one to use such devices as temperature sensors. In an AC magnetic field, they present the advantage of being immune to electromagnetic interference. Moreover, for fiber-Bragg-gratings, the shape factor and small mass of the bare-fiber device make it convenient for temperature measurements on small samples. We studied several thin-film filters and fiber-Bragg-gratings and compared their temperature measurement capabilities in AC magnetic fields of 0 to 150 Gauss, 0 to 20 KHz to the results provided by off-the-shelf thermocouples and thermistor-based temperature measurement systems.

  14. High temperature fiber optic microphone having a pressure-sensing reflective membrane under tensile stress

    NASA Technical Reports Server (NTRS)

    Zuckerwar, Allan J. (Inventor); Cuomo, Frank W. (Inventor); Robbins, William E. (Inventor); Hopson, Purnell, Jr. (Inventor)

    1992-01-01

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

  15. Solar cyclic tests of optical fiber components working in ammonia and high temperatures

    NASA Astrophysics Data System (ADS)

    Fidelus, Janusz D.; Stańczyk, Tomasz; Wysokiński, Karol; Lipiński, Stanisław; Tenderenda, Tadeusz; Rodriguez Garcia, José; Canadas Martinez, Inmaculada; Nasiłowski, Tomasz

    2015-12-01

    The paper reports on the metal (Cu, Ni, Au)-coated fibers annealed under concentrated solar radiation in ammonia and N2/H2 atmospheres at temperatures up to 580 °C. Tensile strength of the annealed fiber components was studied from the point of view of their possible application as a fiber optic sensors in urea chemical synthesis process control.

  16. Optical fiber temperature sensor utilizing alloyed Zn(x)Cd(1-x)S quantum dots.

    PubMed

    Zhao, Fei; Kim, Jongsung

    2014-08-01

    In this paper, optical fiber temperature sensors have been prepared by using alloyed Zn(x)Cd(1-x)S quantum dots as sensing media. The surface of the optical fiber was silanized to enhance covalent bond between quantum dots and optical fiber. The quantum dots were bonded to the surface of optical fiber and further encapsulated via sol-gel coating using 3-glycidoxypropyl trimethoxysilane (GPTMS) and 3-aminopropyl trimethoxysilane (APTMS) in ethyl alcohol in acidic condition. Quantum dots with green, yellow, and red fluorescence were used. The dependence of photoluminescence (PL) intensity from quantum dots on ambient temperature has been studied. Linear relation between the fluorescent intensity and temperature was obtained from alloyed quantum dots immobilized on the surface of optical fiber. The PL intensity, sensitivity, and thermal stability were increased by the silica encapsulation. PMID:25936046

  17. Experimental investigation of the factors influencing temperature dependence of radiation-induced attenuation in optical fiber

    NASA Astrophysics Data System (ADS)

    Jin, Jing; Xu, Raomei; Liu, Jixun; Song, Ningfang

    2014-03-01

    The effects of transmission wavelength, total dose and light source power on temperature dependence of radiation-induced attenuation (RIA) in Ge-P co-doped fibers were investigated. Three fibers irradiated up to total dose of 100 Gy and 10,000 Gy were used as test samples. A test system for temperature dependence of RIA was built up. The influence of transmission wavelength, total dose and light power on temperature sensitivity and linearity of RIA in three irradiated fibers were researched. The test results show that temperature sensitivity and linearity of RIA in optical fibers could be improved by adjusting total dose and selecting transmission wavelength. The light source power does not have obvious influence on temperature sensitivity and linearity. The Ge-P co-doped fiber at 850 nm transmission wavelength with higher total dose is a very promising candidate for fiber-optic temperature sensor.

  18. Influence of high temperatures on optical fibers coated with multilayer protective coatings

    NASA Astrophysics Data System (ADS)

    Stanczyk, T.; Fidelus, J.; Wysokinski, K.; Lipinski, S.; Tenderenda, T.; Kuklińska, M.; Kołakowska, A.; Rodriguez Garcia, J.; Canadas Martinez, I.; Nasiłowski, T.

    2015-12-01

    In this work we present an innovative method of enhancing optical fibers' resistance to extremely high temperatures by deposition of a multilayer metal coating on the fibers' surface. Such multilayer coating is necessary because of the silica degradation at elevated temperatures. Despite the fact that copper coated fibers work well at temperatures up to 400°C, at higher temperatures copper oxidizes and can no longer protect the fiber. To hold back the copper oxidation and silica degradation processes we developed a dedicated multilayer coating which allows fibers to operate at temperatures up to 700°C. The optimal protective layer has been chosen after numerous high-temperature tests, where copper plates coated with different kinds of coatings were evaluated. What is more, we present results of the high-temperature reliability tests of copper coated fibers protected with our multilayer coating. Performed tests proved that our solution significantly improved optical fibers' reliability to both: elevated temperatures and rapid changes of temperature. Furthermore the developed metal coatings allow fibers' to be electrolytically bonded to other metal elements (e.g. sensor transducers) what makes them great candidates for harsh environment fiber optic sensor applications.

  19. A novel fiber optic distributed temperature and strain sensor for building applications

    NASA Astrophysics Data System (ADS)

    Tregubov, A. V.; Svetukhin, V. V.; Novikov, S. G.; Berintsev, A. V.; Prikhodko, V. V.

    A novel fiber optic distributed sensor for temperature and strain measurements in building constructions has been developed and studied which is a composite optical element in the form of a reinforced single-mode optical fiber placed directly in the body of a fiberglass armature. The sensor has a reasonably high sensitivity to changes in external temperature and strain and a good spatial resolution. Besides, it is characterized by a high mechanical strength as compared to conventional fiber sensor elements. The experimental results obtained on a prototype show the value of the temperature sensitivity of 0.1 MHz/deg and the sensitivity to strain of 2.7 MHz/mm.

  20. Two Fiber Optical Fiber Thermometry

    NASA Technical Reports Server (NTRS)

    Jones, Mathew R.; Farmer, Jeffery T.; Breeding, Shawn P.

    2000-01-01

    An optical fiber thermometer consists of an optical fiber whose sensing tip is given a metallic coating. The sensing tip of the fiber is essentially an isothermal cavity, so the emission from this cavity will be approximately equal to the emission from a blackbody. Temperature readings are obtained by measuring the spectral radiative heat flux at the end of the fiber at two wavelengths. The ratio of these measurements and Planck's Law are used to infer the temperature at the sensing tip. Optical fiber thermometers have high accuracy, excellent long-term stability and are immune to electromagnetic interference. In addition, they can be operated for extended periods without requiring re-calibration. For these reasons. it is desirable to use optical fiber thermometers in environments such as the International Space Station. However, it has recently been shown that temperature readings are corrupted by emission from the fiber when extended portions of the probe are exposed to elevated temperatures. This paper will describe several ways in which the reading from a second fiber can be used to correct the corrupted temperature measurements. The accuracy and sensitivity to measurement uncertainty will be presented for each method.

  1. An optical fiber sensing technique for temperature distribution measurements in microwave heating

    NASA Astrophysics Data System (ADS)

    Wada, Daichi; Sugiyama, Jun-ichi; Zushi, Hiroaki; Murayama, Hideaki

    2015-08-01

    We introduce an optical fiber sensing technique that can measure the temperature distributions along a fiber during microwave heating. We used a long-length fiber Bragg grating (FBG) as an electromagnetic-immune sensor and interrogated temperature distributions along the FBG by an optical frequency domain reflectometry. Water in a glass tube with a length of 820 mm was heated in a microwave oven, and its temperature distribution along the glass tube was measured using the sensing system. The temperature distribution was obtained in 5 mm intervals. Infrared radiometry was also used to compare the temperature measurement results. Time and spatial variations of the temperature distribution profiles were monitored for several microwave input powers. The results clearly depict inhomogeneous temperature profiles. The applicability and effectiveness of the optical fiber distributed measurement technique in microwave heating are demonstrated.

  2. Optimum design of 30-km long-distance distributed optical fiber Raman temperature sensor system

    NASA Astrophysics Data System (ADS)

    Zhang, Zaixuan; Liu, Honglin; Wang, Jianfeng; Yu, Xiangdong; Jin, Yongxing; Kim, Insoo S.; Wu, Xiaobiao

    2005-02-01

    A 30km long distance distributed optical fiber Raman temperature sensor (DOFRTS) system has been made, it use new measuring temperature principle of optical fiber amplified anti-Stokes Raman spontaneous scattering. In the system, 1550nm erbium-doped optical fiber laser, a highness speed data acquisition card and signal processing technique are used. By using these technique, the problem of weak signal detection is resolved and signal to noise ratio is increased. All components of system are put into an intellectualized constant temperature box and work in constant temperature condition. Stability and environment adaptability are improved. By appraisal, performance of the system is listed as follows: length of single mode fiber: 31km, temperature rang:0-100°C (can be expanded), temperature measuring uncertainty:+/-2°C, temperature resolution:0.1°C, measurement time:432s, spatial resolution :3m.

  3. Modification of an RBF ANN-Based Temperature Compensation Model of Interferometric Fiber Optical Gyroscopes

    PubMed Central

    Cheng, Jianhua; Qi, Bing; Chen, Daidai; Jr. Landry, René

    2015-01-01

    This paper presents modification of Radial Basis Function Artificial Neural Network (RBF ANN)-based temperature compensation models for Interferometric Fiber Optical Gyroscopes (IFOGs). Based on the mathematical expression of IFOG output, three temperature relevant terms are extracted, which include: (1) temperature of fiber loops; (2) temperature variation of fiber loops; (3) temperature product term of fiber loops. Then, the input-modified RBF ANN-based temperature compensation scheme is established, in which temperature relevant terms are transferred to train the RBF ANN. Experimental temperature tests are conducted and sufficient data are collected and post-processed to form the novel RBF ANN. Finally, we apply the modified RBF ANN based on temperature compensation model in two IFOGs with temperature compensation capabilities. The experimental results show the proposed temperature compensation model could efficiently reduce the influence of environment temperature on the output of IFOG, and exhibit a better temperature compensation performance than conventional scheme without proposed improvements. PMID:25985163

  4. Calculated coupling efficiency between an elliptical-core optical fiber and an optical waveguide over temperature

    NASA Technical Reports Server (NTRS)

    Tuma, Margaret L.; Weisshaar, Andreas; Li, Jian; Beheim, Glenn

    1995-01-01

    To determine the feasibility of coupling the output of a single-mode optical fiber into a single-mode rib waveguide in a temperature varying environment, a theoretical calculation of the coupling efficiency between the two was investigated. Due to the complex geometry of the rib guide, there is no analytical solution to the wave equation for the guided modes, thus, approximation and/or numerical techniques must be utilized to determine the field patterns of the guide. In this study, three solution methods were used for both the fiber and guide fields; the effective-index method (EIM), Marcatili's approximation, and a Fourier method. These methods were utilized independently to calculate the electric field profile of each component at two temperatures, 20 C and 300 C, representing a nominal and high temperature. Using the electric field profile calculated from each method, the theoretical coupling efficiency between an elliptical-core optical fiber and a rib waveguide was calculated using the overlap integral and the results were compared. It was determined that a high coupling efficiency can be achieved when the two components are aligned. The coupling efficiency was more sensitive to alignment offsets in the y direction than the x, due to the elliptical modal field profile of both components. Changes in the coupling efficiency over temperature were found to be minimal.

  5. Temperature sensing up to 1300°C using suspended-core microstructured optical fibers.

    PubMed

    Warren-Smith, Stephen C; Nguyen, Linh Viet; Lang, Catherine; Ebendorff-Heidepriem, Heike; Monro, Tanya M

    2016-02-22

    We demonstrate a new approach to high temperature sensing using femtosecond laser ablation gratings within silica suspended-core microstructured optical fibers. The simple geometry of the suspended-core fiber allows for femtosecond laser processing directly through the fiber cladding. Pure silica glass is used, allowing the sensor to be used up to temperatures as high as 1300°C while still allowing the fibre to be spliced to conventional fiber. The sensor can also be wavelength division multiplexed, with three sensors in a single fiber demonstrated. PMID:26907027

  6. Sputtered metallic coatings for optical fibers used in high-temperature environments

    NASA Astrophysics Data System (ADS)

    Gunther, Michael F.; Zeakes, Jason S.; Lieber, Donald E.; May, Russell G.; Claus, Richard O.

    1994-05-01

    Rf and dc planar magnetron sputtering systems were used to deposit high-temperature nickel- based super alloys, INCONEL 617, 625, Haynes 214, and thin films of palladium, as coatings on optical fibers for use in temperatures approaching 1000 degree(s)C. The nickel-based alloy coatings were applied on-line as the optical fiber was drawn, minimizing the exposure of the fiber to the deleterious effects of humidity. The thin film coatings of pure metals were sputtered using a new rf magnetron sputtering system custom designed and built for the Fiber and Electro Optics Research Center. The resulting coatings were analyzed using scanning electron microscopy, Auger electron microscopy, and energy dispersive x-ray spectroscopy. The coated fibers exhibit promise for embedded sensors in high temperature, high load composites used for advanced aerospace and energy applications.

  7. Demonstrated survivability of a high temperature optical fiber cable on a 1500 pound thrust rocket chamber

    NASA Technical Reports Server (NTRS)

    Sovie, Amy L.

    1992-01-01

    A demonstration of the ability of an existing optical fiber cable to survive the harsh environment of a rocket engine was performed at the NASA Lewis Research Center. The intent of this demonstration was to prove the feasibility of applying fiber optic technology to rocket engine instrumentation systems. Extreme thermal transient tests were achieved by wrapping a high temperature optical fiber, which was cablized for mechanical robustness, around the combustion chamber outside wall of a 1500 lb Hydrogen-Oxygen rocket engine. Additionally, the fiber was wrapped around coolant inlet pipes which were subject to near liquid hydrogen temperatures. Light from an LED was sent through the multimode fiber, and output power was monitored as a function of time while the engine was fired. The fiber showed no mechanical damage after 419 firings during which it was subject to transients from 30 K to 350 K, and total exposure time to near liquid hydrogen temperatures in excess of 990 seconds. These extreme temperatures did cause attenuation greater than 3 dB, but the signal was fully recovered at room temperature. This experiment demonstrates that commercially available optical fiber cables can survive the environment seen by a typical rocket engine instrumentation system, and disclose a temperature-dependent attenuation observed during exposure to near liquid hydrogen temperatures.

  8. Optical Fibers

    NASA Astrophysics Data System (ADS)

    Ghatak, Ajoy; Thyagarajan, K.

    With the development of extremely low-loss optical fibers and their application to communication systems, a revolution has taken fiber glass place during the last 40 years. In 2001, using glass fibers as the transmission medium and lightwaves as carrier wave waves, information was transmitted at a rate more than 1 Tbit/s (which is roughly equivalent to transmission of about 15 million simultaneous telephone conversations) through one hair thin optical fiber. Experimental demonstration of transmission at the rate of 14 Tbit/s over a 160 km long single fiber was demonstrated in 2006, which is equivalent to sending 140 digital high definition movies in 1 s. Very recently record transmission of more than 100 Tbit/s over 165 km single mode fiber has been reported. These can be considered as extremely important technological achievements. In this chapter we will discuss the propagation characteristics of optical fibers with special applications to optical communication systems and also present some of the noncommunication applications such as sensing.

  9. Compensation for effects of ambient temperature on rare-earth doped fiber optic thermometer

    NASA Technical Reports Server (NTRS)

    Adamovsky, G.; Sotomayor, J. L.; Krasowski, M. J.; Eustace, J. G.

    1990-01-01

    Variations in ambient temperature have a negative effect on the performance of any fiber optic sensing system. A change in ambient temperature may alter the design parameters of fiber optic cables, connectors, sources, detectors, and other fiber optic components and eventually the performance of the entire system. The thermal stability of components is especially important in a system which employs intensity modulated sensors. Several referencing schemes have been developed to account for the variable losses that occur within the system. However, none of these conventional compensating techniques can be used to stabilize the thermal drift of the light source in a system based on the spectral properties of the sensor material. The compensation for changes in ambient temperature becomes especially important in fiber optic thermometers doped with rare earths. Different approaches to solving this problem are searched and analyzed.

  10. Compensation for effects of ambient temperature on rare-earth doped fiber optic thermometer

    NASA Technical Reports Server (NTRS)

    Adamovsky, G.; Sotomayor, J. L.; Krasowski, M. J.; Eustace, J. G.

    1989-01-01

    Variations in ambient temperature have a negative effect on the performance of any fiber optic sensing system. A change in ambient temperature may alter the design parameters of fiber optic cables, connectors, sources, detectors, and other fiber optic components and eventually the performance of the entire system. The thermal stability of components is especially important in a system which employs intensity modulated sensors. Several referencing schemes have been developed to account for the variable losses that occur within the system. However, none of these conventional compensating techniques can be used to stabilize the thermal drift of the light source in a system based on the spectral properties of the sensor material. The compensation for changes in ambient temperature becomes especially important in fiber optic thermometers doped with rare earths. Different approaches to solving this problem are searched and analyzed.

  11. Fabrication of miniature fiber-optic temperature sensors

    DOEpatents

    Zhu, Yizheng; Wang, Anbo

    2010-07-27

    A method of coupling a silica fiber and a sapphire fiber includes providing a silica fiber having a doped core and a cladding layer, with the doped core having a prescribed diameter, providing a sapphire fiber having a diameter less than the doped core, placing an end of the sapphire fiber in close proximity to an end of the silica fiber, applying a heat source to the end of silica fiber and introducing the end of sapphire fiber into the heated doped core of the silica fiber to produce a coupling between the silica and sapphire fibers.

  12. Multimode fiber-optic Mach-Zehnder interferometer and its use in temperature measurement.

    PubMed

    Okamoto, T; Yamaguchi, I

    1988-08-01

    A fiber-optic Mach-Zehnder interferometer with multimode fibers has been constructed, in which the fringe shift is detected by a spatial filtering detector. In this interferometer, throughput is much greater than in interferometers using single-mode fibers, but speckles disturb detection of the fringe shift. We have overcome this disadvantage by computer software; the interferometer measured temperature and a sensitivity of 72.3 +/- 1.2 fringes/ degrees C . m was obtained. PMID:20531897

  13. Optical high temperature sensor based on fiber Bragg grating

    NASA Astrophysics Data System (ADS)

    Zhang, Bowei

    The aim of this thesis is to fabricate a fiber Bragg grating (FBG) temperature sensor that is capable to measure temperatures in excess of 1100°C. For this purpose, two topics have been studied and investigated during this project. One of them is the development of a high temperature resistant molecular-water induced FBGs; and the other is to investigate the effect of microwave-irradiation on the hydrogen-loaded FBG. The molecular-water induced FBGs are different from the other types of FBG. In these devices the refractive index is modulated by the periodic changes of molecular-water concentration within the grating. The device was developed using thermal annealing technology based on hydrogen-load FBG. Thermal stability of these devices was studied by measuring the grating reflectivity from room temperature to 1000°C. The stability of the device was tested by examining the FBG reflectivity for a period of time at certain temperatures. The results show that these devices are extremely stable at temperatures in excess of 1000°C. The hydroxyl concentration in the grating has been also investigated during this thesis. Based on the knowledge of hydroxyl groups inside FBG, a microwave treatment was designed to increase the hydroxyl concentration in the FBG area. The results show that the molecular-water induced grating, which was fabricated using microwave radiated hydrogen-loaded FBI, are stable at temperatures above 1100°C.

  14. Miniature all-silica fiber-optic sensor for simultaneous measurement of relative humidity and temperature.

    PubMed

    Pevec, Simon; Donlagic, Denis

    2015-12-01

    This Letter presents a miniature fiber-optic sensor created at the tip of an optical fiber suitable for simultaneous measurement of relative humidity and temperature. The proposed sensor is based on two cascaded Fabry-Perot interferometers, the first configured as a relative humidity sensing element made from silica micro-wire coated with thin porous SiO2 layer, and the second as a temperature sensing element made from a segment of a standard single-mode fiber. The sensor has linear characteristics for both measurement parameters and a sensitivity of 0.48 deg/%RH and 3.7 deg/°C. PMID:26625072

  15. Single mode step-index polymer optical fiber for humidity insensitive high temperature fiber Bragg grating sensors.

    PubMed

    Woyessa, Getinet; Fasano, Andrea; Stefani, Alessio; Markos, Christos; Nielsen, Kristian; Rasmussen, Henrik K; Bang, Ole

    2016-01-25

    We have fabricated the first single-mode step-index and humidity insensitive polymer optical fiber operating in the 850 nm wavelength ranges. The step-index preform is fabricated using injection molding, which is an efficient method for cost effective, flexible and fast preparation of the fiber preform. The fabricated single-mode step-index (SI) polymer optical fiber (POF) has a 4.8µm core made from TOPAS grade 5013S-04 with a glass transition temperature of 134°C and a 150 µm cladding made from ZEONEX grade 480R with a glass transition temperature of 138°C. The key advantages of the proposed SIPOF are low water absorption, high operating temperature and chemical inertness to acids and bases and many polar solvents as compared to the conventional poly-methyl-methacrylate (PMMA) and polystyrene based POFs. In addition, the fiber Bragg grating writing time is short compared to microstructured POFs. PMID:26832507

  16. Magnetometer probe with low temperature rotation and optical fibers

    NASA Astrophysics Data System (ADS)

    Pajerowski, D. M.; Meisel, M. W.

    2009-02-01

    A new probe has been developed that allows for both optical irradiation and uniaxial rotation, all in the low temperature environment of a commercial superconducting quantum interference device (SQUID) magnetometer. As part of the design process, various materials were investigated and characterized for their low temperature structural and magnetic properties, including nylon, Vespel, Delrin, Spiderwire monofilament, and PowerPro braided microfilament. Using this information, a prototype was built and operated. Characteristics of the probe will be presented along with a summary of the low temperature (T >= 2 K) and high magnetic field (H <= 7 T) properties of the construction materials.

  17. Theoretical modeling of a Localized Surface Plasmon Resonance (LSPR) based fiber optic temperature sensor

    NASA Astrophysics Data System (ADS)

    Algorri, J. F.; García-Cámara, B.; García-García, A.; Urruchi, V.; Sánchez-Pena, J. M.

    2014-05-01

    A localized surface plasmon resonance based fiber optic sensor for temperature sensing has been analyzed theoretically. The effects of the size of the spherical metal nanoparticle on the performance of the sensor have been studied in detail. The high sensitivity of localized surface plasmon resonances to refraction index changes, in collaboration with the high thermo-optic coefficients of Liquid Crystal materials, has result in a fiber optical sensor with high temperature sensitivity. This sensitivity has been demonstrated to be dependent on nanoparticle size. Maximum sensitivities of 4nm/°C can be obtained for some specific temperature ranges. The proposed sensor will be low cost, and will have all the typical advantages of fiber optic sensors.

  18. Interface reaction of optical glass fiber sintered with low-temperature sealing glass

    NASA Astrophysics Data System (ADS)

    Xu, Bo; Liu, Guoying; Zu, Chengkui; Gao, Xiping; Han, Bin; Zhu, Baojing; Yin, Xianyin

    2014-12-01

    Low-temperature sealing glass (320-380°C) can be applied to the hermetic package of optical fiber devices, without the need of metallization. This paper introduced a PbO-ZnO-B2O3-F system low-temperature glass composite which has an softening point as low as 246°C and expansion coefficient of 8.0 ppm/°C. The glass composite was sealed with quartz glass fibers at 360-390°C, then the effect of sintering temperature and holding time on the surface reaction were well investigated. Although the mismatch of expansion coefficient exists within glass fiber, negative expansion filler and parent glass, they combined well with each other after a short time heating. The F- in glass network helped to lower the sealing temperature, wet the oxide surface and promote the combination of parent glass and fibers. The sealing temperature and holding time affect the interface layer and the shape of the fiber. The optimum packaging process should be sealing composite glass and fibers beneath 380°C with shortened holding time as possible. Using glazed glass composite preforms, sealing fiber in a ferrule to achieve compressed package will be helpful to realize hermetic package for optical fiber devices.

  19. High-temperature fiber-optic Fabry-Perot interferometric sensors

    SciTech Connect

    Ding, Wenhui; Jiang, Yi; Gao, Ran; Liu, Yuewu

    2015-05-15

    A photonic crystal fiber (PCF) based high-temperature fiber-optic sensor is proposed and experimentally demonstrated. The sensor head is a Fabry-Perot cavity manufactured with a short section of endless single-mode photonic crystal fiber (ESM PCF). The interferometric spectrum of the Fabry-Perot interferometer is collected by a charge coupled device linear array based micro spectrometer. A high-resolution demodulation algorithm is used to interrogate the peak wavelengths. Experimental results show that the temperature range of 1200 °C and the temperature resolution of 1 °C are achieved.

  20. High-temperature fiber-optic Fabry-Perot interferometric sensors.

    PubMed

    Ding, Wenhui; Jiang, Yi; Gao, Ran; Liu, Yuewu

    2015-05-01

    A photonic crystal fiber (PCF) based high-temperature fiber-optic sensor is proposed and experimentally demonstrated. The sensor head is a Fabry-Perot cavity manufactured with a short section of endless single-mode photonic crystal fiber (ESM PCF). The interferometric spectrum of the Fabry-Perot interferometer is collected by a charge coupled device linear array based micro spectrometer. A high-resolution demodulation algorithm is used to interrogate the peak wavelengths. Experimental results show that the temperature range of 1200 °C and the temperature resolution of 1 °C are achieved. PMID:26026548

  1. Development and Performance Verification of Fiber Optic Temperature Sensors in High Temperature Engine Environments

    NASA Technical Reports Server (NTRS)

    Adamovsky, Grigory; Mackey, Jeffrey R.; Kren, Lawrence A.; Floyd, Bertram M.; Elam, Kristie A.; Martinez, Martel

    2014-01-01

    A High Temperature Fiber Optic Sensor (HTFOS) has been developed at NASA Glenn Research Center for aircraft engine applications. After fabrication and preliminary in-house performance evaluation, the HTFOS was tested in an engine environment at NASA Armstrong Flight Research Center. The engine tests enabled the performance of the HTFOS in real engine environments to be evaluated along with the ability of the sensor to respond to changes in the engine's operating condition. Data were collected prior, during, and after each test in order to observe the change in temperature from ambient to each of the various test point levels. An adequate amount of data was collected and analyzed to satisfy the research team that HTFOS operates properly while the engine was running. Temperature measurements made by HTFOS while the engine was running agreed with those anticipated.

  2. Scheme of optical fiber temperature sensor employing deep-grooved process optimization

    NASA Astrophysics Data System (ADS)

    Liu, Yu; Liu, Cong; Xiang, Gaolin; Wang, Ruijie; Wang, Yibing; Xiang, Lei; Wu, Linzhi; Liu, Song

    2015-03-01

    To optimize the optical fiber temperature sensor employing the deep-grooved process, a novel scheme was proposed. Fabricated by the promising CO2 laser irradiation system based on the two-dimensional scanning motorized stage with high precision, the novel deep-grooved optical fiber temperature sensor was obtained with its temperature sensitivity of the transmission attenuation -0.107 dB/°C, which was 18.086 times higher than the optical fiber sensor with the normal depth of grooves while other parameters remained unchanged. The principal research and experimental testing showed that the designed temperature sensor measurement unit had the ability of high sensitivity in transmission attenuation and insensitivity to the wavelength, which offers possible applications in engineering.

  3. Fiber-optic multiband radiometer for online measurements of near room temperature and emissivity.

    PubMed

    Uman, Igor; Katzir, Abraham

    2006-02-01

    A multiband infrared fiber-optic radiometer was developed for online near room temperature and emissivity measurements. Real time measurements were carried out on gray and selective bodies at near room temperature. The mean accuracy obtained for the body temperature was roughly 1 degrees C and for emissivity was roughly 0.03. The radiometer is capable of performing measurements without prior knowledge of the body emissivity. Incorporation of fiber optics allows one to perform measurements without a clear line of sight between the radiometer and the body. This radiometer will have important applications in biology, electronics, and other areas. PMID:16480197

  4. 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.

  5. [New type distributed optical fiber temperature sensor (DTS) based on Raman scattering and its' application].

    PubMed

    Wang, Jian-Feng; Liu, Hong-Lin; Zhang, Shu-Qin; Yu, Xiang-Dong; Sun, Zhong-Zhou; Jin, Shang-Zhong; Zhang, Zai-Xuan

    2013-04-01

    Basic principles, development trends and applications status of distributed optical fiber Raman temperature sensor (DTS) are introduced. Performance parameters of DTS system include the sensing optical fiber length, temperature measurement uncertainty, spatial resolution and measurement time. These parameters have a certain correlation and it is difficult to improve them at the same time by single technology. So a variety of key techniques such as Raman amplification, pulse coding technique, Raman related dual-wavelength self-correction technique and embedding optical switching technique are researched to improve the performance of the DTS system. A 1 467 nm continuous laser is used as pump laser and the light source of DTS system (1 550 nm pulse laser) is amplified. When the length of sensing optical fiber is 50 km the Raman gain is about 17 dB. Raman gain can partially compensate the transmission loss of optical fiber, so that the sensing length can reach 50 km. In DTS system using pulse coding technique, pulse laser is coded by 211 bits loop encoder and correlation calculation is used to demodulate temperature. The encoded laser signal is related, whereas the noise is not relevant. So that signal-to-noise ratio (SNR) of DTS system can be improved significantly. The experiments are carried out in DTS system with single mode optical fiber and multimode optical fiber respectively. Temperature measurement uncertainty can all reach 1 degrees C. In DTS system using Raman related dual-wavelength self-correction technique, the wavelength difference of the two light sources must be one Raman frequency shift in optical fiber. For example, wavelength of the main laser is 1 550 nm and wavelength of the second laser must be 1 450 nm. Spatial resolution of DTS system is improved to 2 m by using dual-wavelength self-correction technique. Optical switch is embedded in DTS system, so that the temperature measurement channel multiply extended and the total length of the sensing

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

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

  7. Factors influencing the temperature sensitivity of PMMA based optical fiber Bragg gratings

    NASA Astrophysics Data System (ADS)

    Zhang, Wei; Webb, David J.

    2014-05-01

    The Bragg wavelength of a PMMA based fiber grating is determined by the effective core index and the grating pitch, which, in temperature sensing, depend on the thermo-optic and thermal expansion coefficients of PMMA. These two coefficients are a function of surrounding temperature and humidity. Amorphous polymers including PMMA exhibit a certain degree of anisotropic thermal expansion. The anisotropic nature of expansion mainly depends on the polymer processing history. The expansion coefficient is believed to be lower in the direction of the molecular orientation than in the direction perpendicular to the draw direction. Such anisotropic behavior of polymers can be expected in drawn PMMA based optical fiber, and will lead to a reduced thermal expansion coefficient and larger temperature sensitivity than would be the case were the fiber to be isotropic. Extensive work has been carried out to identify these factors. The temperature responses of gratings have been measured at different relative humidity. Gratings fabricated on annealed and non-annealed PMMA optical fibers are used to compare the sensitivity performance as annealing is considered to be able to mitigate the anisotropic effect in PMMA optical fiber. Furthermore an experiment has been designed to eliminate the thermal expansion contribution to the grating wavelength change, leading to increased temperature sensitivity and improved response linearity.

  8. Fire Source Localization Based on Distributed Temperature Sensing by a Dual-Line Optical Fiber System.

    PubMed

    Sun, Miao; Tang, Yuquan; Yang, Shuang; Li, Jun; Sigrist, Markus W; Dong, Fengzhong

    2016-01-01

    We propose a method for localizing a fire source using an optical fiber distributed temperature sensor system. A section of two parallel optical fibers employed as the sensing element is installed near the ceiling of a closed room in which the fire source is located. By measuring the temperature of hot air flows, the problem of three-dimensional fire source localization is transformed to two dimensions. The method of the source location is verified with experiments using burning alcohol as fire source, and it is demonstrated that the method represents a robust and reliable technique for localizing a fire source also for long sensing ranges. PMID:27275822

  9. 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

  10. Fire Source Localization Based on Distributed Temperature Sensing by a Dual-Line Optical Fiber System

    PubMed Central

    Sun, Miao; Tang, Yuquan; Yang, Shuang; Li, Jun; Sigrist, Markus W.; Dong, Fengzhong

    2016-01-01

    We propose a method for localizing a fire source using an optical fiber distributed temperature sensor system. A section of two parallel optical fibers employed as the sensing element is installed near the ceiling of a closed room in which the fire source is located. By measuring the temperature of hot air flows, the problem of three-dimensional fire source localization is transformed to two dimensions. The method of the source location is verified with experiments using burning alcohol as fire source, and it is demonstrated that the method represents a robust and reliable technique for localizing a fire source also for long sensing ranges. PMID:27275822

  11. Application of fiber optic temperature and strain sensing technology to gas hydrates

    SciTech Connect

    Ulrich, Shannon M; Madden, Megan Elwood; Rawn, Claudia J; Szymcek, Phillip; Phelps, Tommy Joe

    2008-01-01

    Gas hydrates may have a significant influence on global carbon cycles due to their large carbon storage capacity in the form of greenhouse gases and their sensitivity to small perturbations in local conditions. Characterizing existing gas hydrate and the formation of new hydrate within sediment systems and their response to small changes in temperature and pressure is imperative to understanding how this dynamic system functions. Fiber optic sensing technology offers a way to measure precisely temperature and strain in harsh environments such as the seafloor. Recent large-scale experiments using Oak Ridge National Laboratory's Seafloor Process Simulator were designed to evaluate the potential of fiber optic sensors to study the formation and dissociation of gas hydrates in 4-D within natural sediments. Results indicate that the fiber optic sensors are so sensitive to experimental perturbations (e.g. refrigeration cycles) that small changes due to hydrate formation or dissociation can be overshadowed.

  12. Enhancing the sensitivity of poly(methyl methacrylate) based optical fiber Bragg grating temperature sensors.

    PubMed

    Zhang, Wei; Webb, David J; Peng, Gang-Ding

    2015-09-01

    In poly(methyl methacrylate) (PMMA)-based optical fiber gratings (POFBGs), the temperature response is determined by thermal expansion and the thermo-optic effect of the fiber. Because thermal expansion introduces a positive change and the thermo-optic effect introduces a negative change in the Bragg wavelength of the POFBG, they cancel out each other to some extent, leading to reduced and varying temperature sensitivity. By pre-straining a POFBG, the contribution of thermal expansion can be removed, and, consequently, the temperature sensitivity of POFBG can be greatly enhanced. Theoretical analysis also indicates a reduced thermo-optic coefficient of POFBG due to restrained linear expansion that matches experimental results. PMID:26368708

  13. Distributed Temperature and Strain Discrimination with Stimulated Brillouin Scattering and Rayleigh Backscatter in an Optical Fiber

    PubMed Central

    Zhou, Da-Peng; Li, Wenhai; Chen, Liang; Bao, Xiaoyi

    2013-01-01

    A distributed optical fiber sensor with the capability of simultaneously measuring temperature and strain is proposed using a large effective area non-zero dispersion shifted fiber (LEAF) with sub-meter spatial resolution. The Brillouin frequency shift is measured using Brillouin optical time-domain analysis (BOTDA) with differential pulse-width pair technique, while the spectrum shift of the Rayleigh backscatter is measured using optical frequency-domain reflectometry (OFDR). These shifts are the functions of both temperature and strain, and can be used as two independent parameters for the discrimination of temperature and strain. A 92 m measurable range with the spatial resolution of 50 cm is demonstrated experimentally, and accuracies of ±1.2 °C in temperature and ±15 με in strain could be achieved. PMID:23385406

  14. Embedded infrared fiber-optic sensor for thermometry in a high temperature/pressure environment

    NASA Astrophysics Data System (ADS)

    Yoo, Wook Jae; Jang, Kyoung Won; Moon, Jinsoo; Han, Ki-Tek; Jeon, Dayeong; Lee, Bongsoo; Park, Byung Gi

    2012-11-01

    In this study, we developed an embedded infrared fiber-optic temperature sensor for thermometry in high temperature/pressure and water-chemistry environments by using two identical silver-halide optical fibers. The performance of the fabricated temperature sensor was assessed in an autoclave filled with an aqueous coolant solution containing boric acid and lithium hydroxide. We carried out real-time monitoring of the infrared radiation emitted from the signal and reference probes for various temperatures over a temperature range from 95 to 225 °C. In order to decide the temperature of the synthetic coolant solution, we measured the difference between the infrared radiation emitted from the two temperature-sensing probes. Thermometry with the proposed sensor is immune to any changes in the physical conditions and the emissivity of the heat source. From the experimental results, the embedded infrared fiber-optic temperature sensor can withstand, and normally operate in a high temperature/pressure test loop system corresponding to the coolant system used for nuclear power plant simulation. We expect that the proposed sensor can be developed to accurately monitor temperatures in harsh environments.

  15. Effect of stress and temperature on the optical phonons of aramid fibers

    NASA Astrophysics Data System (ADS)

    Bollas, D.; Parthenios, J.; Galiotis, C.

    2006-03-01

    The wave-number dependence upon stress and/or strain and temperature of two adjacent optical phonons of aramid fibers has been investigated. The results showed that both phonons soften considerably under axial tension. Experiments at various temperatures under fixed strain conditions have demonstrated that one of the phonons (ν1=1611cm-1) is moderately anharmonic whereas the adjacent phonon (ν2=1648cm-1) exhibits harmonic behavior. By modeling the fibers as one-dimensional molecular wires very good agreement between experiment and theory is obtained for the phonon temperature dependence under isostress conditions.

  16. Fabrication and comparison of thermochromic material-based fiber-optic sensors for monitoring the temperature of water

    NASA Astrophysics Data System (ADS)

    Yoo, Wook Jae; Seo, Jeong Ki; Jang, Kyoung Won; Heo, Ji Yeon; Moon, Jin Soo; Park, Jang-Yeon; Park, Byung Gi; Lee, Bongsoo

    2011-01-01

    In this study, we explored the feasibility of developing two types of fiber-optic temperature sensors that can measure the temperature of water. One uses a thermochromic material such as Lophine, whose optical absorbance changes according to the thermal variation. The other uses a thermochromic pigment that gradually loses its own color through heat absorption. We measured the change in the intensity of the reflected light, which was due to the variation of the optical property of Lophine and pigments, with thermal variation. The relationship between the temperature of water and the output signal of the fiber-optic sensors was also determined. The fiber-optic temperature sensor using Lophine provided a relatively broad range of temperature measurement with low sensitivity, whereas the fiber-optic temperature sensor using a thermochromic pigment offered a high sensitivity in a narrow range of temperature measurement.

  17. Optical fiber sensor for temperature measurement from 600 to 1900 C in gas turbine engines

    NASA Technical Reports Server (NTRS)

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

    1991-01-01

    A temperature sensor system has been fabricated specifically for the harsh environment encountered in temperature measurement on gas turbine engines. Four components comprised the system: a thermally emissive source, a high temperature lightguide, a flexible optical cable and an electro-optic signal processor. The emissive source was located inside a sapphire rod so that the sapphire serves as both a lightguide and as a protective shroud. As the probe was heated, the thermal radiation from the emissive source increased with increasing temperature. The flexible optical cable was constructed with 200 micron core fiber and ruggedized for turbine engine applications. The electro-optic signal processor used the ratio of intensity in two wavelength intervals to determine a digital value of the temperature. The probe tip was operated above 1900 C in a low velocity propane flame and above 1500 C at Mach .37. Probe housings, optical cables, and signal processors were constructed and environmentally tested for the temperature and vibration experienced by turbine engine sensors. This technology was used to build an optical exhaust gas sensor for a General Electric Aircraft Engines F404 turbine. The four optical probes and optical cable were a functional replacement for four thermocouple probes. The system was ground tested for 50 hours with an excess of 1000 thermal cycles. This optical temperature sensor system measured gas temperature up to the operational limit of the turbine engine.

  18. Temperature Measurement of Power Cable Based on Distributed Optical Fiber Sensor

    NASA Astrophysics Data System (ADS)

    Shen, Xiaoqing; Yang, Yang; Cong, Bo; Ding, Fenghai; Qiu, Bin; Ye, Lingling

    2016-02-01

    To measure the temperature of the power cable onboard ships efficiently, a design scheme based on distributed optical fiber sensor is proposed. In this paper, its principle and hardware are described in detail and its feasibility and effectiveness is verified through real test.

  19. Fiber-optic thermometer using temperature dependent absorption, broadband detection, and time domain referencing

    NASA Technical Reports Server (NTRS)

    Adamovsky, Grigory; Piltch, Nancy D.

    1986-01-01

    A fiber-optic thermometer based on temperature dependent absorption in Nd(3+) doped glass is demonstrated over the 298-573 K range. A broadband detection technique allows the use of the complete spectrum of a pulse modulated light emitting diode. A fiber-optic recirculating loop is employed to construct a reference channel in the time domain by generating a train of pulses from one initial pulse. A theoretical model is developed, and experimental data are shown to compare well with the theory. Possible sources of error and instability are identified, and ways to enhance the performance of the system are proposed.

  20. Fiber optics for controls

    NASA Technical Reports Server (NTRS)

    Seng, Gary T.

    1987-01-01

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

  1. Study of optical fibers strain-temperature sensitivities using hybrid Brillouin-Rayleigh system

    NASA Astrophysics Data System (ADS)

    Kishida, Kinzo; Yamauchi, Yoshiaki; Guzik, Artur

    2014-03-01

    In this paper, the most recent progress as well as challenges of distributed optical fiber sensing (DOFS) in industrial applications is discussed. Compared to the vast market of sensors used to measure strain or temperature, the success of distributed optical fiber sensing (DOFS) at the industrial level is very limited, at best. One of the reasons for this lack of the wider acceptance is the mismatch between the commercially available systems and actual industrial requirements, especially for the spatial resolution and precision. These requirements are organized and clarified in the paper. It also describes the hybrid Brillouin-Rayleigh system, which exhibits capabilities surpassing those of strain gauges. The principles of the system are illustrated considering the fiber calibration methodology. Formulas required for determining strain, temperature, and hydro-pressure are derived and discussed. Finally, the examples of applications are presented.

  2. A plastic optical fiber sensor for the dual sensing of temperature and oxygen

    NASA Astrophysics Data System (ADS)

    Lo, Yu-Lung; Chu, Chen-Shane

    2008-04-01

    This study presents a low-cost plastic optical fiber sensor for the dual sensing of temperature and oxygen. The sensor features a commercially available epoxy glue coated on the side-polished fiber surface for temperature sensing and a fluorinated xerogel doped with platinum tetrakis pentrafluoropheny porphine (PtTFPP) coated on the fiber end for oxygen sensing. The temperature and oxygen indicators are both excited using a UV LED light source with a wavelength of 380 nm. The luminescence emission spectra of the two indicators are well resolved and exhibit no cross-talk effects. Overall, the results indicate that the dual sensor presented in this study provides an ideal solution for the non-contact, simultaneous sensing of temperature and oxygen in general biological and medical applications.

  3. 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.

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

    PubMed Central

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

    2016-01-01

    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. PMID:27409620

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

    PubMed

    Khan, Md Rajibur Rahaman; Kang, Shin-Won

    2016-01-01

    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. PMID:27409620

  6. Fiber optic monitoring device

    DOEpatents

    Samborsky, James K.

    1993-01-01

    A device for the purpose of monitoring light transmissions in optical fibers comprises a fiber optic tap that optically diverts a fraction of a transmitted optical signal without disrupting the integrity of the signal. The diverted signal is carried, preferably by the fiber optic tap, to a lens or lens system that disperses the light over a solid angle that facilitates viewing. The dispersed light indicates whether or not the monitored optical fiber or system of optical fibers is currently transmitting optical information.

  7. Temperature sensor using an optical fiber coupler with a thin film.

    PubMed

    Guo, Hairun; Pang, Fufei; Zeng, Xianglong; Chen, Na; Chen, Zhenyi; Wang, Tingyun

    2008-07-01

    A temperature sensor was demonstrated and fabricated by coating thermosensitive film around a fiber coupler. Based on the multicladding equivalent method, the coated fiber coupler was simplified to a conventional one. With the high thermo-optical coefficient of organic-inorganic solgel material, a good sensing result was achieved. The range of temperature measured is from -50 to 100 degrees C. The resonant wavelength has a shift of about 25 nm. A sensitivity of 0.17 nm/degrees C is achieved. With the advantages of having a simple structure and being unaffected by the instability of the light source, the proposed fiber coupler temperature sensor will find wide applications. PMID:18594600

  8. Method and apparatus for determining peak temperature along an optical fiber

    DOEpatents

    Fox, Richard J.

    1985-01-01

    The invention relates to a new method and new apparatus for determining the hottest temperature or the coldest temperature prevailing along the length of an optical-fiber light guide. The invention is conducted with an optical fiber capable of supporting multidiode propagation of light and comprising a core, a cladding, and a jacket. The core is selected to have (1) a higher refractive index than the core and the cladding and (2) a relatively high negative temperature coefficient of refractive index. A light beam capable of establishing substantially single-mode propagation in the core is launched into an end thereof at an angle to the axis. The angle is increased to effect the onset of light refraction from the core into the cladding. The value of the launch angle corresponding to the onset is determined and then used to establish the refractive index of the core corresponding to the onset angle. The maximum temperature prevailing along the fiber then is determined from the (1) refractive index so determined and (2) the temperature coefficient of refractive index for the core. The invention is based on the finding that the launch angle corresponding to the onset of refraction into the cladding is uniquely determined by the maximum value of the ratio of the core refractive index to the cladding refractive index, which maximum occurs at the hottest point along the fiber.

  9. Method and apparatus for determining peak temperature along an optical fiber

    DOEpatents

    Fox, R.J.

    1982-07-29

    The invention relates to a new method and new apparatus for determining the hottest temperature or the coldest temperature prevailing along the length of an optical-fiber light guide. The invention is conducted with an optical fiber capable of supporting multidiode propagation of light and comprising a core, a cladding, and a jacket. The core is selected to have (1) a higher refractive index than the core and the cladding and (2) a relatively high negative temperature coefficient of refractive index. A light beam capable of establishing substantially single-mode propagation in the core is launched into an end thereof at an angle to the axis. The angle is increased to effect the onset of light fraction from the core into the cladding. The value of the launch angle corresponding to the onset is determined and then used to establish the refractive index of the core corresponding to the onset angle. The maximum temperature prevailing along the fiber then is determined from the (1) refractive index so determined and (2) the temperature coefficient of refractive index for the core. The invention is based on the finding that the launch angle corresponding to the onset of refraction into the cladding is uniquely determined by the maximum value of the ratio of the core refractive index to the cladding refractive index, which maximum occurs at the hottest point along the fiber.

  10. Fiber-optic temperature sensor based on interaction of temperature-dependent refractive index and absorption of germanium film.

    PubMed

    Li, Min; Li, Yulin

    2011-01-10

    The interaction of a large temperature-dependent refractive index and a temperature-dependent absorption of semiconductor materials at 1550 nm can be used to build a very sensitive, film coated fiber-optic temperature probe. We developed a sensor model for the optical fiber-germanium film sensor. A temperature sensitivity of reflectivity change of 0.0012/°C, corresponding to 0.1°C considering a moderate signal processing system, over 100°C within the temperature regime of -20°C to 120°C, has been demonstrated by experimental tests of the novel sensor. The potential sensitivity and further applications of the sensor are discussed. PMID:21221150

  11. Fiber optic sensor for hydrostatic pressure and temperature measurement in riverbanks monitoring

    NASA Astrophysics Data System (ADS)

    Schenato, Luca; Aneesh, Rajendran; Palmieri, Luca; Galtarossa, Andrea; Pasuto, Alessandro

    2016-08-01

    An optical fiber sensor for the simultaneous measurement of hydrostatic pressure and temperature in soil embankments is presented. It exploits the differential strain induced on a fiber in a dual-chamber case, constituting the sensor body. The strain, either induced by the pressure or by the temperature, is optically measured by means of coherent frequency domain reflectometry and variations induced by the two physical phenomena are discriminated because of the different behavior of the two chambers. Characterization of the sensor is presented and discussed. The prototype shows promising performance: temperature and pressure sensitivities are approximately -7 GHz/°C and -3.2 GHz/kPa, respectively, with accuracies of 0.5 °C and 0.3 kPa.

  12. 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.

  13. Locating illicit connections in storm water sewers using fiber-optic distributed temperature sensing.

    PubMed

    Hoes, O A C; Schilperoort, R P S; Luxemburg, W M J; Clemens, F H L R; van de Giesen, N C

    2009-12-01

    A newly developed technique using distributed temperature sensing (DTS) has been developed to find illicit household sewage connections to storm water systems in the Netherlands. DTS allows for the accurate measurement of temperature along a fiber-optic cable, with high spatial (2m) and temporal (30s) resolution. We inserted a fiber-optic cable of 1300m in two storm water drains. At certain locations, significant temperature differences with an intermittent character were measured, indicating inflow of water that was not storm water. In all cases, we found that foul water from households or companies entered the storm water system through an illicit sewage connection. The method of using temperature differences for illicit connection detection in storm water networks is discussed. The technique of using fiber-optic cables for distributed temperature sensing is explained in detail. The DTS method is a reliable, inexpensive and practically feasible method to detect illicit connections to storm water systems, which does not require access to private property. PMID:19735929

  14. Plasmonic nanocomposite thin film enabled fiber optic sensors for simultaneous gas and temperature sensing at extreme temperatures

    NASA Astrophysics Data System (ADS)

    Ohodnicki, Paul R.; Buric, Michael P.; Brown, Thomas D.; Matranga, Christopher; Wang, Congjun; Baltrus, John; Andio, Mark

    2013-09-01

    Embedded sensors capable of operation in extreme environments including high temperatures, high pressures, and highly reducing, oxidizing and/or corrosive environments can make a significant impact on enhanced efficiencies and reduced greenhouse gas emissions of current and future fossil-based power generation systems. Relevant technologies can also be leveraged in a wide range of other applications with similar needs including nuclear power generation, industrial process monitoring and control, and aviation/aerospace. Here we describe a novel approach to embedded sensing under extreme temperature conditions by integration of Au-nanoparticle based plasmonic nanocomposite thin films with optical fibers in an evanescent wave absorption spectroscopy configuration. Such sensors can potentially enable simultaneous temperature and gas sensing at temperatures approaching 900-1000 °C in a manner compatible with embedded and distributed sensing approaches. The approach is demonstrated using the Au/SiO2 system deposited on silica-based optical fibers. Stability of optical fibers under relevant high temperature conditions and interactions with changing ambient gas atmospheres is an area requiring additional investigation and development but the simplicity of the sensor design makes it potentially cost-effective and may offer a potential for widespread deployment.Embedded sensors capable of operation in extreme environments including high temperatures, high pressures, and highly reducing, oxidizing and/or corrosive environments can make a significant impact on enhanced efficiencies and reduced greenhouse gas emissions of current and future fossil-based power generation systems. Relevant technologies can also be leveraged in a wide range of other applications with similar needs including nuclear power generation, industrial process monitoring and control, and aviation/aerospace. Here we describe a novel approach to embedded sensing under extreme temperature conditions by

  15. Observation of temperature dependence of the IR hydroxyl absorption bands in silica optical fiber

    NASA Astrophysics Data System (ADS)

    Yu, Li; Bonnell, Elizabeth; Homa, Daniel; Pickrell, Gary; Wang, Anbo; Ohodnicki, P. R.; Woodruff, Steven; Chorpening, Benjamin; Buric, Michael

    2016-07-01

    This study reports on the temperature dependent behavior of silica based optical fibers upon exposure to high temperatures in hydrogen and ambient air. The hydroxyl absorption bands in the wavelength range of 1000-2500 nm of commercially available multimode fibers with pure silica and germanium doped cores were examined in the temperature range of 20-800 °C. Two hydroxyl-related infrared absorption bands were observed: ∼2200 nm assigned to the combination of the vibration mode of Si-OH bending and the fundamental hydroxyl stretching mode, and ∼1390 nm assigned to the first overtone of the hydroxyl stretching. The absorption in the 2200 nm band decreased in intensity, while the 1390 nm absorption band shifted to longer wavelengths with an increase in temperature. The observed phenomena were reversible with temperature and suspected to be due, in part, to the conversion of the OH spectral components into each other and structural relaxation.

  16. Temperature and pressure fiber-optic sensors applied to minimally invasive diagnostics and therapies

    NASA Astrophysics Data System (ADS)

    Hamel, Caroline; Pinet, Éric

    2006-02-01

    We present how fiber-optic temperature or pressure sensors could be applied to minimally invasive diagnostics and therapies. For instance a miniature pressure sensor based on micro-optical mechanical systems (MOMS) could solve most of the problems associated with fluidic pressure transduction presently used for triggering purposes. These include intra-aortic balloon pumping (IABP) therapy and other applications requiring detection of fast and/or subtle fluid pressure variations such as for intracranial pressure monitoring or for urology diagnostics. As well, miniature temperature sensors permit minimally invasive direct temperature measurement in diagnostics or therapies requiring energy transfer to living tissues. The extremely small size of fiber-optic sensors that we have developed allows quick and precise in situ measurements exactly where the physical parameters need to be known. Furthermore, their intrinsic immunity to electromagnetic interference (EMI) allows for the safe use of EMI-generating therapeutic or diagnostic equipments without compromising the signal quality. With the trend of ambulatory health care and the increasing EMI noise found in modern hospitals, the use of multi-parameter fiber-optic sensors will improve constant patient monitoring without any concern about the effects of EMI disturbances. The advantages of miniature fiberoptic sensors will offer clinicians new monitoring tools that open the way for improved diagnostic accuracy and new therapeutic technologies.

  17. Variable temperature system using vortex tube cooling and fiber optic temperature measurement for low temperature magic angle spinning NMR.

    PubMed

    Martin, Rachel W; Zilm, Kurt W

    2004-06-01

    We describe the construction and operation of a variable temperature (VT) system for a high field fast magic angle spinning (MAS) probe. The probe is used in NMR investigations of biological macromolecules, where stable setting and continuous measurement of the temperature over periods of several days are required in order to prevent sample overheating and degradation. The VT system described is used at and below room temperature. A vortex tube is used to provide cooling in the temperature range of -20 to 20 degrees C, while a liquid nitrogen-cooled heat exchanger is used below -20 degrees C. Using this arrangement, the lowest temperature that is practically achievable is -140 degrees C. Measurement of the air temperature near the spinning rotor is accomplished using a fiber optic thermometer that utilizes the temperature dependence of the absorption edge of GaAs. The absorption edge of GaAs also has a magnetic field dependence that we have measured and corrected for. This dependence was calibrated at several field strengths using the well-known temperature dependence of the (1)H chemical shift difference of the protons in methanol. PMID:15140428

  18. Temperature-independent refractometer based on fiber-optic Fabry-Perot interferometer

    NASA Astrophysics Data System (ADS)

    Li, Jiacheng; Qiao, Xueguang; Wang, Ruohui; Rong, Qiangzhou; Bao, Weijia; Shao, Zhihua; Yang, Tingting

    2016-04-01

    A miniature fiber-optic refractometer based on Fabry-Perot interferometer (FPI) has been proposed and experimentally demonstrated. The sensing head consists of a short section of photonics crystal fiber (PCF) spliced to a single mode fiber (SMF), in which the end-face of the PCF is etched to remove holey structure with hydrofluoric (HF) acid. A Fabry-Perot interference spectrum is achieved based on the reflections from the fusion splicing interface and the end-face of the core of PCF. The interference fringe is sensitive to the external refractive index (RI) with an intensity-referenced sensitivity of 358.27 dB/RIU ranging from 1.33 to 1.38. The sensor has also been implemented for the concentration measurement of λ-phage DNA solution. In addition, the dip intensity is insensitive to the ambient temperature variation, making it a good candidate for temperature-independent bio-sensing area.

  19. Fiber optic thermo-hygrometers for soil moisture and temperature measurements: the SFORI project

    NASA Astrophysics Data System (ADS)

    Leone, M.; Consales, M.; Laudati, A.; Mennella, F.; Cutolo, A.; Cusano, A.

    2015-09-01

    This work deals with the development of fiber optic sensors for the measurement of soil moisture and temperature over large areas. It has been carried out within the Regional Project "Sensoristica in Fibra Ottica per il Risparmio Idrico - SFORI". The sensor system is based on the fiber Bragg gratings (FBGs) technology and is aimed at optimizing the irrigation practice in order to guarantee a sustainable water resources management. Two sensors networks, each one based on FBG thermo-hygrometers, have been realized and installed in two experimental sites. Preliminary results envisages good perspectives for a massive usage of the proposed technology.

  20. Reflective polarimetric vibration sensor based on temperature-independent FBG in HiBi microstructured optical fiber

    NASA Astrophysics Data System (ADS)

    Chah, Karima; Caucheteur, Christophe; Mégret, Patrice; Sulejmani, Sanne; Geernaert, Thomas; Thienpont, Hugo; Berghmans, Francis; Wuilpart, Marc

    2014-05-01

    Fiber optic sensors outperform traditional sensor technologies in fields such as structural health monitoring, vibration and seismic activity monitoring, intrusion detection, and many other applications. Their key advantages include electromagnetic interference immunity, lightweight, small size, multiplexing capabilities, low power consumption, corrosion and high temperature resistance. To meet the demand of more and more challenging optical sensors a new generation of optical fibers, the so-called microstructured optical fibers (MOFs), has appeared. These fibers are composed of a structure of holes surrounding a solid core, which offers a unique design flexibility to optimize their waveguide properties for specific applications. In particular, the design can be optimized to strongly reduce the cross-sensitivity of a sensor to parasitic physical parameters like temperature variations, as is the case for the sensor presented here. Our sensor is based on a Bragg grating inside a temperature independent highly birefringent MOF with a high transverse strain sensitivity, to evaluate vibrations by a polarimetric measurement of the reflection spectrum. This technique takes advantage of the stress-induced phase shift between the two orthogonally polarized fiber eigenmodes. It consists in coupling linearly polarized light through one arm of an optical coupler (50:50) in the sensing optical fiber in which a highly reflective fiber Bragg grating is inscribed. The reflected signal is analysed through a linear polarizer. The optical fiber is crushed by a mechanical transducer designed to transform the vibration into a mechanical stress transversal to the fiber's axis. The vibration therefore induces a change of the phase modal birefringence that varies in time at the vibration frequency. In this study we show that using standard single-mode fibers to realize the sensor do not provide stable measurements and that using conventional polarization-maintaining fibers lead to a

  1. Electrospun Amplified Fiber Optics

    PubMed Central

    2015-01-01

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

  2. Double-Ended Calibration of Fiber-Optic Raman Spectra Distributed Temperature Sensing Data

    PubMed Central

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

    2012-01-01

    Over the past five years, Distributed Temperature Sensing (DTS) along fiber optic cables using Raman backscattering has become an important tool in the environmental sciences. Many environmental applications of DTS demand very accurate temperature measurements, with typical RMSE < 0.1 K. The aim of this paper is to describe and clarify the advantages and disadvantages of double-ended calibration to achieve such accuracy under field conditions. By measuring backscatter from both ends of the fiber optic cable, one can redress the effects of differential attenuation, as caused by bends, splices, and connectors. The methodological principles behind the double-ended calibration are presented, together with a set of practical considerations for field deployment. The results from a field experiment are presented, which show that with double-ended calibration good accuracies can be attained in the field. PMID:22778596

  3. Analysis and modeling for fiber-optic gyroscope scale factor based on environment temperature.

    PubMed

    Shen, Chong; Chen, Xiyuan

    2012-05-10

    To explore and reduce the nonlinear error and temperature dependency of fiber-optic gyroscope (FOG) scale factor, a scale factor modeling method based on temperature is presented in this paper. A hyperbolic curve fitting is proposed according to the characteristic of scale factor under stable temperature at first. Compared to traditional modeling methods, it shows that a higher precision model of scale factor can be obtained. Then the influence of temperature on scale factor is analyzed and then the hyperbolic curve fitting method is extended based on temperature, making it possible to work over the whole potential temperature range of the FOG without degrading the performance. This paper also provides the experimental and verification results. It can be seen that a high precision model of scale factor has been established, the temperature dependency of scale factor has been reduced effectively, and the error due to environment temperature is reduced by one order at least. PMID:22614471

  4. Fiber-optic pulsed photothermal radiometry for fast surface-temperature measurements.

    PubMed

    Eyal, O; Scharf, V; Katzir, A

    1998-09-01

    Temperature measurement based on pulsed photothermal radiometry is described. In this technique a body is irradiated by a laser pulse and its temperature is inferred from the shape of the emitted photothermal-signal curve. A prototypical system based on a pulsed CO(2) laser, an IR detector, and IR-transmitting silver halide optical fibers was constructed and used to evaluate the feasibility of this technique. An important feature of the technique is that changes in sample emissivity or geometric factors do not introduce errors in the temperature determination. Theory, simulation, and experimental results are given and discussed. PMID:18286089

  5. Fiber optic distributed temperature sensor mapping of a jet-mixing flow field

    SciTech Connect

    Lomperski, Stephen; Gerardi, Craig; Pointer, William David

    2015-03-04

    In this paper, we introduce the use of a Rayleigh backscatter-based distributed fiber optic sensor to map the temperature field in air flow for a thermal fatigue application. The experiment involves a pair of air jets at 22 and 70°C discharging from 136 mm hexagonal channels into a 1 × 1 × 1.7 m tank at atmospheric pressure. A 40 m-long, Φ155 µm fiber optic sensor was wound back and forth across the tank midplane to form 16 horizontal measurement sections with a vertical spacing of 51 mm. This configuration generated a 2D temperature map with 2800 data points over a 0.76 × 1.7 m plane. Fiber optic sensor readings were combined with PIV and infrared measurements to relate flow field characteristics to the thermal signature of the tank lid. The paper includes sensor stability data and notes issues encountered using the distributed temperature sensor in a flow field. In conclusion, sensors are sensitive to strain and humidity, and so accuracy relies upon strict control of both.

  6. Fiber optic distributed temperature sensor mapping of a jet-mixing flow field

    DOE PAGESBeta

    Lomperski, Stephen; Gerardi, Craig; Pointer, William David

    2015-03-04

    In this paper, we introduce the use of a Rayleigh backscatter-based distributed fiber optic sensor to map the temperature field in air flow for a thermal fatigue application. The experiment involves a pair of air jets at 22 and 70°C discharging from 136 mm hexagonal channels into a 1 × 1 × 1.7 m tank at atmospheric pressure. A 40 m-long, Φ155 µm fiber optic sensor was wound back and forth across the tank midplane to form 16 horizontal measurement sections with a vertical spacing of 51 mm. This configuration generated a 2D temperature map with 2800 data points overmore » a 0.76 × 1.7 m plane. Fiber optic sensor readings were combined with PIV and infrared measurements to relate flow field characteristics to the thermal signature of the tank lid. The paper includes sensor stability data and notes issues encountered using the distributed temperature sensor in a flow field. In conclusion, sensors are sensitive to strain and humidity, and so accuracy relies upon strict control of both.« less

  7. Self Similar Optical Fiber

    NASA Astrophysics Data System (ADS)

    Lai, Zheng-Xuan

    This research proposes Self Similar optical fiber (SSF) as a new type of optical fiber. It has a special core that consists of self similar structure. Such a structure is obtained by following the formula for generating iterated function systems (IFS) in Fractal Theory. The resulted SSF can be viewed as a true fractal object in optical fibers. In addition, the method of fabricating SSF makes it possible to generate desired structures exponentially in numbers, whereas it also allows lower scale units in the structure to be reduced in size exponentially. The invention of SSF is expected to greatly ease the production of optical fiber when a large number of small hollow structures are needed in the core of the optical fiber. This dissertation will analyze the core structure of SSF based on fractal theory. Possible properties from the structural characteristics and the corresponding applications are explained. Four SSF samples were obtained through actual fabrication in a laboratory environment. Different from traditional conductive heating fabrication system, I used an in-house designed furnace that incorporated a radiation heating method, and was equipped with automated temperature control system. The obtained samples were examined through spectrum tests. Results from the tests showed that SSF does have the optical property of delivering light in a certain wavelength range. However, SSF as a new type of optical fiber requires a systematic research to find out the theory that explains its structure and the associated optical properties. The fabrication and quality of SSF also needs to be improved for product deployment. As a start of this extensive research, this dissertation work opens the door to a very promising new area in optical fiber research.

  8. Reduction of the effect of temperature in a fiber optic distributed sensor used for strain measurements in civil structures

    NASA Astrophysics Data System (ADS)

    Ohno, Hiroshige; Uchiyama, Yasuomi; Kurashima, Toshio

    1999-05-01

    We report on an approach for reducing the effects of temperature in a fiber optic distributed sensor. This technique employs a sensing fiber and a Brillouin optical time domain reflectometer (BOTDR). The BOTDR has been proposed for measuring both strain and optical loss distribution along optical fibers by accessing only one end of the fiber. The BOTDR analyzes changes in the Brillouin frequency shift caused by strain. This device can measure distributed strain with an accuracy of better than plus or minus 60 X 10-6 and a high spatial resolution of up to 1 m over a 10 km long fiber. However, temperature fluctuations have an adverse effect on the accuracy with which the Brillouin frequency shift can be measured because the shift changes with temperature as well as with strain. This has meant that both spatial and temporal fluctuations in temperature must be compensated for when a fiber optic distributed sensor is used for continuous strain measurements in massive civil structures. We describe a method for the simultaneous determination of distributed strain and temperature which separates strain and temperature in a fiber optic sensor.

  9. FOREX: a fiber-optics diagnostic system for study of materials at high temperatures and pressures

    SciTech Connect

    Smith, D.E.; Roeske, F.

    1982-07-01

    We have successfully fielded a Fiber Optics Radiation Experiment system (FOREX) designed for measuring material properties at high temperatures and pressures in an underground nuclear test. The system collects light from radiating materials and transmits it through several hundred meters of optical fibers to a recording station consisting of a streak camera with film readout. The use of fiber optics provides a faster time response than can presently be obtained with equalized coaxial cables over comparable distances. Fibers also have significant cost and physical size advantages over coax cables. The streak camera achieves a much higher information density than an equivalent oscilloscope system, and it also serves as the light detector. The result is a wide bandwidth high capacity system that can be fielded at a relatively low cost in manpower, space, and materials. For this experiment, the streak camera had a 120 ns time window with a 1.2 ns time resolution. Dynamic range for the system was about 1000. Beam current statistical limitations were approximately 8% for a 0.3 ns wide data point at one decade above the threshold recording intensity.

  10. FOREX-A Fiber Optics Diagnostic System For Study Of Materials At High Temperatures And Pressures

    NASA Astrophysics Data System (ADS)

    Smith, D. E.; Roeske, F.

    1983-03-01

    We have successfully fielded a Fiber Optics Radiation EXperiment system (FOREX) designed for measuring material properties at high temperatures and pressures on an underground nuclear test. The system collects light from radiating materials and transmits it through several hundred meters of optical fibers to a recording station consisting of a streak camera with film readout. The use of fiber optics provides a faster time response than can presently be obtained with equalized coaxial cables over comparable distances. Fibers also have significant cost and physical size advantages over coax cables. The streak camera achieves a much higher information density than an equivalent oscilloscope system, and it also serves as the light detector. The result is a wide bandwidth high capacity system that can be fielded at a relatively low cost in manpower, space, and materials. For this experiment, the streak camera had a 120 ns time window with a 1.2 ns time resolution. Dynamic range for the system was about 1000. Beam current statistical limitations were approximately 8% for a 0.3 ns wide data point at one decade above the threshold recording intensity.

  11. Fiber optic connector

    DOEpatents

    Rajic, S.; Muhs, J.D.

    1996-10-22

    A fiber optic connector and method for connecting composite materials within which optical fibers are imbedded are disclosed. The fiber optic connector includes a capillary tube for receiving optical fibers at opposing ends. The method involves inserting a first optical fiber into the capillary tube and imbedding the unit in the end of a softened composite material. The capillary tube is injected with a coupling medium which subsequently solidifies. The composite material is machined to a desired configuration. An external optical fiber is then inserted into the capillary tube after fluidizing the coupling medium, whereby the optical fibers are coupled. 3 figs.

  12. Fiber optic connector

    DOEpatents

    Rajic, Slobodan; Muhs, Jeffrey D.

    1996-01-01

    A fiber optic connector and method for connecting composite materials within which optical fibers are imbedded. The fiber optic connector includes a capillary tube for receiving optical fibers at opposing ends. The method involves inserting a first optical fiber into the capillary tube and imbedding the unit in the end of a softened composite material. The capillary tube is injected with a coupling medium which subsequently solidifies. The composite material is machined to a desired configuration. An external optical fiber is then inserted into the capillary tube after fluidizing the coupling medium, whereby the optical fibers are coupled.

  13. Magnetic resonance imaging-guided interstitial application of laser aided by fiber optic temperature sensing

    NASA Astrophysics Data System (ADS)

    Farahani, Keyvan; Shellock, Frank G.; Lufkin, Robert B.; Castro, Dan J.

    1992-04-01

    In order to further understand signal variations observed on magnetic resonance imaging scans of interstitial laser heating, a commercial multichannel fluoroptic thermometer, equipped with fiber optic sensors, was employed in conjunction with the laser/MRI phototherapy system. Three calibrated fiber optic sensors of the thermometer were used to measure temperature changes in ex-vivo sheep's brain at various distances directly across from the beam of a Nd:YAG laser emitted from a bare fiber. Laser was operated at 5 W for 220 sec. Temperature was measured every 10 seconds and MR images were acquired during and after laser irradiation until temperature in all probes returned to the equilibrium level of prelaser irradiation. Image contrast analysis of the heated region showed that MRI signal variations, during heating and cooling periods, correlated well with the changes in temperature. It is concluded that direct thermometry of MRI-monitored laser application will aid in understanding the effects of high focal heating on the MRI signal.

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

    SciTech Connect

    Kennedy, Jermaine L.

    2009-03-12

    This project aimed to develop a multifunctional sensor suitable for process control application in chemical and petrochemical industries. Specifically, the objective was to demonstrate a fiber optic sensing system capable of simultaneous temperature, pressure, and chemical composition determinations based on a single strand of sapphire optical fiber. These capabilities were to be achieved through the incorporation of a phosphor and a Bragg grating into the fiber, as well as the exploitation of the evanescent field interaction of the optical radiation inside the fiber with the surrounding chemical medium. The integration of the three functions into a single probe, compared to having three separate probes, would not only substantially reduce the cost of the combined system, but would also minimize the intrusion into the reactor. Such a device can potentially increase the energy efficiency in the manufacture of chemical and petrochemical products, as well as reduce waste and lead to improved quality. In accordance with the proposed research plan, the individual temperature, pressure and chemical sensors where fabricated and characterized first. Then towards the end of the program, an integrated system was implemented. The sapphire fibers were grown on a laser heated pedestal growth system. The temperature sensor was based on the fluorescence decay principle, which exploits the temperature dependence of the fluorescence decay rate of the selected phosphor. For this project, Cr3+ was chosen as the phosphor, and it was incorporated into the sapphire fiber by coating a short length of the source rod with a thin layer of Cr2O3. After the viability of the technique was established and the growth parameters optimized, the temperature sensor was characterized up to 300 °C and its long term stability was verified. The chemical sensor determined the concentration of chemicals through evanescent field absorption. Techniques to increase the

  15. Heated fiber optic distributed temperature sensing: a tool for measuring soil water content

    NASA Astrophysics Data System (ADS)

    Rodriguez-Sinobas, Leonor; Zubelzu, Sergio; Sánchez-Calvo, Raúl; Horcajo, Daniel

    2016-04-01

    The use of Distributed Fiber Optic Temperature Measurement (DFOT) method for estimating temperature variation along a cable of fiber optic has been assessed in multiple environmental applications. Recently, the application of DFOT combined with an active heating pulses technique has been reported as a sensor to estimate soil moisture. This method applies a known amount of heat to the soil and monitors the temperature evolution, which mainly depends on the soil moisture content . This study presents the application of the Active Heated DFOT method to determine the soil water retention curve under experimental conditions. The experiment was conducted in a rectangular methacrylate box of 2.5 m x 0.25 m x 0.25 m which was introduced in a larger box 2.8 m x 0.3 m x 0.3 m of the same material. The inner box was filled with a sandy loamy soil collected from the nearest garden and dried under ambient temperature for 30 days. Care was taking to fill up the box maintaining the soil bulk density determined "in-situ". The cable was deployed along the box at 10 cm depth. At the beginning of the experiment, the box was saturated bottom-up, by filling the outer box with water, and then it kept dried for two months. The circulation of heated air at the bottom box accelerated the drying process. In addition, fast growing turf was also sowed to dry it fast. The DTS unit was a SILIXA ULTIMA SR (Silixa Ltd, UK) and has spatial and temporal resolution of 0.29 m and 5 s, respectively. In this study, heat pulses of 7 W/m for 2 1/2 min were applied uniformly along the fiber optic cable and the thermal response on an adjacent cable was monitored in different soil water status. Then, the heating and drying phase integer (called Tcum) was determined following the approach of Sayde et al., (2010). For each water status,  was measured by the gravimetric method in several soil samples collected in three box locations at the same depth that the fiber optic cable and after each heat pulse

  16. Fast-response fiber-optic anemometer with temperature self-compensation.

    PubMed

    Liu, Guigen; Hou, Weilin; Qiao, Wei; Han, Ming

    2015-05-18

    We report a novel fiber-optic anemometer with self-temperature compensation capability based on a Fabry-Pérot interferometer (FPI) formed by a thin silicon film attached to the end face of a single-mode fiber. Guided in the fiber are a visible laser beam from a 635 nm diode laser used to heat the FPI and a white-light in the infrared wavelength range as the signal light to interrogate the optical length of the FPI. Cooling effects on the heated sensor head by wind is converted to a wavelength blueshift of the reflection spectral fringes of the FPI. Self-temperature-compensated measurement of wind speed is achieved by recording the difference in fringe wavelengths when the heating laser is turned on and then off. Large thermal-optic coefficient and thermal expansion coefficient of silicon render a high sensitivity that can also be easily tuned by altering the heating laser power. Furthermore, the large thermal diffusivity and the small mass of the thin silicon film endow a fast sensor response. PMID:26074604

  17. Drastic sensitivity enhancement of temperature sensing based on modal interference in plastic optical fibers

    NASA Astrophysics Data System (ADS)

    Numata, G.; Hayashi, N.; Tabaru, M.; Mizuno, Y.; Nakamura, K.

    2015-09-01

    It has been reported that temperature sensors based on modal interference in perfluorinated graded-index (GI) plastic optical fibers (POFs) show the world's highest temperature sensitivity of +49.8 nm/°C/m at 1300 nm at room temperature, which is over 1800 times the value in silica multimode fibers (MMFs). In this work, we newly find that the temperature sensitivity (absolute value) is significantly enhanced with increasing temperature toward ~70°C, which is close to the glass-transition temperature of the core polymer. When the core diameter is 62.5 μm, the sensitivity at 72 °C at 1300 nm is +202 nm/°C/m, which is approximately 26 times the value obtained at room temperature and even over 7000 times the highest value previously reported using a silica MMF. As the glass-transition temperature of polymers can be generally set to an arbitrary value, this characteristic could be used to develop POF-based temperature sensors with ultra-high sensitivity not only at ~70°C but at arbitrary temperature in future.

  18. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2013-05-01

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

  20. Compensation method for temperature error of fiber optical gyroscope based on relevance vector machine.

    PubMed

    Wang, Guochen; Wang, Qiuying; Zhao, Bo; Wang, Zhenpeng

    2016-02-10

    Aiming to improve the bias stability of the fiber optical gyroscope (FOG) in an ambient temperature-change environment, a temperature-compensation method based on the relevance vector machine (RVM) under Bayesian framework is proposed and applied. Compared with other temperature models such as quadratic polynomial regression, neural network, and the support vector machine, the proposed RVM method possesses higher accuracy to explain the temperature dependence of the FOG gyro bias. Experimental results indicate that, with the proposed RVM method, the bias stability of an FOG can be apparently reduced in the whole temperature ranging from -40°C to 60°C. Therefore, the proposed method can effectively improve the adaptability of the FOG in a changing temperature environment. PMID:26906376

  1. Experimental study of low-cost fiber optic distributed temperature sensor system performance

    NASA Astrophysics Data System (ADS)

    Dashkov, Michael V.; Zharkov, Alexander D.

    2016-03-01

    The distributed control of temperature is an actual task for various application such as oil & gas fields, high-voltage power lines, fire alarm systems etc. The most perspective are optical fiber distributed temperature sensors (DTS). They have advantages on accuracy, resolution and range, but have a high cost. Nevertheless, for some application the accuracy of measurement and localization aren't so important as cost. The results of an experimental study of low-cost Raman based DTS based on standard OTDR are represented.

  2. Measuring centimeter-resolution air temperature profiles above land and water using fiber-optic Distributed Temperature Sensing

    NASA Astrophysics Data System (ADS)

    Sigmund, Armin; Pfister, Lena; Olesch, Johannes; Thomas, Christoph K.

    2016-04-01

    The precise determination of near-surface air temperature profiles is of special importance for the characterization of airflows (e.g. cold air) and the quantification of sensible heat fluxes according to the flux-gradient similarity approach. In contrast to conventional multi-sensor techniques, measuring temperature profiles using fiber-optic Distributed Temperature Sensing (DTS) provides thousands of measurements referenced to a single calibration standard at much reduced costs. The aim of this work was to enhance the vertical resolution of Raman scatter DTS measurements up to the centimeter-scale using a novel approach for atmospheric applications: the optical fiber was helically coiled around a meshed fabric. In addition to testing the new fiber geometry, we quantified the measurement uncertainty and demonstrated the benefits of the enhanced-resolution profiles. The fiber-optic cable was coiled around a hollow column consisting of white reinforcing fabric supported by plexiglass rings every meter. Data from two columns of this type were collected for 47 days to measure air temperature vertically over 3.0 and 5.1 m over a gently inclined meadow and over and in a small lake, respectively. Both profiles had a vertical resolution of 1 cm in the lower section near the surface and 5 cm in the upper section with an along-fiber instrument-specific averaging of 1.0 m and a temporal resolution of 30 s. Measurement uncertainties, especially from conduction between reinforcing fabric and fiber-optic cable, were estimated by modeling the fiber temperature via a detailed energy balance approach. Air temperature, wind velocity and radiation components were needed as input data and measured separately. The temperature profiles revealed valuable details, especially in the lowest 1 m above surface. This was best demonstrated for nighttime observations when artefacts due to solar heating did not occur. For example, the dynamics of a cold air layer was detected in a clear night

  3. Small-scale variability of alpine snow packs from fiber-optic distributed temperature

    NASA Astrophysics Data System (ADS)

    Huwald, H.; Williams, S.; Higgins, C. W.; Nolin, A. W.; Drake, S. A.; Selker, J. S.; Parlange, M. B.

    2012-04-01

    Variations in small-scale surface roughness, snow density and in the snowpack microstructure influence the surface and internal snow temperature, being key quantities for various heat flux components of the surface energy balance. Detailed knowledge on the spatial distribution and temporal evolution of snow temperature is crucial to quantify spatial variability in the subsurface and surface heat fluxes of the snow pack. We present measurements of small-scale temperature variations in alpine snow packs using fiber-optic distributed temperature sensing (DTS) together with traditional sensors at spatial resolutions much smaller than most common distributed snow cover models to shed light on subgrid-scale physics. Fiber-optic cables of several 100m were installed in a fence-like configuration in in the Swiss Alps to obtain 2D information on subgrid-scale snow variability. The setup allowed for computation of subsurface heat fluxes at 1m spatial resolution along the measurement transect based on the Fourier heat equation using snow temperature and snow depth data, and an effective thermal conductivity of the snow derived from density measurements.

  4. A hybrid fiber-optic sensing system for down-hole pressure and distributed temperature measurements

    NASA Astrophysics Data System (ADS)

    Chen, Ke; Zhou, Xinlei; Yang, Bokai; Peng, Wei; Yu, Qingxu

    2015-10-01

    A hybrid fiber-optic sensing technique, combining the extrinsic Fabry-Perot interferometer (EFPI) based pressure sensor with the incoherent optical frequency domain reflectometry (IOFDR) based distributed temperature sensor (DTS), is presented for down-hole measurements. By using a laser diode as the common light source, a highly integrated hybrid EFPI/DTS sensing system has been developed with a single fiber. With the injection current of the laser diode below lasing threshold, the broadband spontaneous emission light is used for EFPI based pressure sensing; while with the injection current above the threshold, the stimulated emission light is used for Raman based distributed temperature sensing. There is no overlap between the spectral range of the reflected light from the EFPI sensor and the spectral range of the Raman scattered light. Pressure and distributed temperature can thus be measured by using wavelength-division multiplexing (WDM) technology. Experimental results show that both the pressure and the distributed temperature are measured with little interference. Furthermore, the pressure measurement can be compensated by the measured temperature values.

  5. Reduced graphene oxide coated optical fiber for methanol and ethanol vapor detection at room temperature

    NASA Astrophysics Data System (ADS)

    Kavinkumar, T.; Sastikumar, D.; Manivannan, S.

    2014-10-01

    Successful isolation of single layer of graphene from graphite by mechanical exfoliation method, attracted a great attention due to its unique structural, optical, mechanical and electronic properties. This makes the graphene as a promising material in many possible applications such as energy-storage, sensing, electronic, optical devices and polymer composite materials. High quality of reduced graphene oxide (rGO) material was prepared by chemical reduction method at 100°C. The structural and optical properties of the rGO sheets were characterized by FT-IR, micro Raman, powder XRD and UV-vis-NIR techniques. FT-IR reveals the absence of oxygen functional groups on rGO due to the reduction process. Powder XRD shows the broad peak at 2θ=24.3° corresponding to interlayer spacing 3.66Å which is smaller than the graphene oxide (GO). UV-vis-NIR of rGO displays the absorption peak at 271 nm indicates the reduction of GO and the restoration of C=C bonds in the rGO sheets. The cladding removed and rGO coated poly-methyl methacrylate (PMMA) optical fiber is used for methanol and ethanol vapors detection in the concentration ranging from 0 to 500 ppm at room temperature. The spectral characteristics along with output intensity modulation of cladding removed and rGO coated fiber optic sensor reveal the potential of methanol and ethanol vapor sensing properties.

  6. Temperature dependence of light power propagation in bending plastic optical fiber

    NASA Astrophysics Data System (ADS)

    Jing, Ning; Teng, Chuanxin; Zheng, Jie; Wang, Guanjun; Zhang, Minjuan; Wang, Zhibin

    2016-09-01

    This study investigates the effect of temperature variation on the light power propagation in bending plastic optical fiber (POF). The transmittance of bending POFs with curvature radius of 2-30 mm and turns of 1/4, 1/2, 1, and 2 are measured over temperature of 20-70 °C. The temperature dependent loss of the bending POF is obtained. It is found that the temperature dependent loss of the bending POF changes with curvature radius and turns. The temperature effect reaches the highest value of 0.011 dB/°C with 2 turns, and is less than 0.002 dB/°C with curvature radius greater than 25 mm.

  7. Effect of the glass transition of coating adhesive on temperature performance of fiber optic gyroscope and its optimization

    NASA Astrophysics Data System (ADS)

    Wang, Yueze; Wang, Tieshui; Ma, Lin; Yu, Hao; Liu, Bohan

    2015-10-01

    The fiber optic gyroscope (FOG)based on Sagnac effect has became to one of the most important sensors in developing due to light in quality, high accuracy, compact in dimension and long life and has played a very important role in both military and civil use. It is the most difficult problem that the FOG has an obvious bias drift caused by temperature change and temperature grade, so its application is limited to a great extent. Fiber coil is one of the most critical components in FOG. Here, the characteristic of temperature error of the fiber optical coil was analyzed. At first, by studying the glass transition of coating adhesive in the fiber coil, the element model of the fiber coil with the glass transition of coating adhesive in FOG was built. Then the discrete mathematics model of SHUPE error with the glass transition of coating adhesive in FOG was built. Finally, based on the temperature models mentioned above, the effects caused by the glass transition of coating adhesive on temperature performance of fiber optic gyroscope were analyzed. Theoretical analysis and experimental results show that effect caused by the glass transition of coating adhesive had seriously affected the temperature performance of FOG. By optimizing the glass transition temperature of coating adhesive, the SHUPE error of fiber coils can be reduced. At the same time, the amplitude uniformity of the SHUPE error can be improved greatly to reduce the difficulty in temperature compensation.

  8. A fiber-optic interferometer based on non-adiabatic fiber taper and long-period fiber grating for simultaneous measurement of magnetic field and temperature

    NASA Astrophysics Data System (ADS)

    Kang, Shouxin; Zhang, Hao; Liu, Bo; Lin, Wei; Zhang, Ning; Miao, Yinping

    2016-01-01

    A dual-parameter sensor based on a fiber-optic interferometer consisting of a non-adiabatic fiber taper and a long-period fiber grating (LPFG) integrated with magnetic nanoparticle fluids has been proposed and experimentally demonstrated. Due to the Mach-Zehnder interference induced by the concatenation of the fiber taper and long-period grating, an interferometric spectrum could be acquired within the transmission resonance spectral envelope of the LPFG. Thanks to different magnetic field and temperature sensitivities of difference interference dips, simultaneous measurement of the magnetic field intensity and environmental temperature could be achieved. Moreover, due to the variation in coupling coefficients of the fiber taper and the LPFG in response to the change of the applied magnetic field intensity, some of the interference dips would exhibit opposite magnetic-field-intensity-dependent transmission loss variation behavior. Magnetic field intensity and temperature sensitivities of 0.017 31 dB Oe-1 and 0.0315 dB K-1, and -0.024 55 dB Oe-1 and -0.056 28 dB K-1 were experimentally acquired for the experimentally monitored interference dips.

  9. Fiber optic monitoring device

    DOEpatents

    Samborsky, J.K.

    1993-10-05

    A device for the purpose of monitoring light transmissions in optical fibers comprises a fiber optic tap that optically diverts a fraction of a transmitted optical signal without disrupting the integrity of the signal. The diverted signal is carried, preferably by the fiber optic tap, to a lens or lens system that disperses the light over a solid angle that facilitates viewing. The dispersed light indicates whether or not the monitored optical fiber or system of optical fibers is currently transmitting optical information. 4 figures.

  10. Fiber optic monitoring device

    SciTech Connect

    Samborsky, J.K.

    1992-12-31

    This invention is comprised of a device for the purpose of monitoring light transmissions in optical fibers comprises a fiber optic tap that optically diverts a fraction of a transmitted optical signal without disrupting the integrity of the signal. The diverted signal is carried, preferably by the fiber optic tap, to a lens or lens system that disperses the light over a solid angle that facilitates viewing. The dispersed light indicates whether or not the monitored optical fiber or system of optical fibers is currently transmitting optical information.

  11. Fiber Optic Sensors for Temperature Monitoring during Thermal Treatments: An Overview.

    PubMed

    Schena, Emiliano; Tosi, Daniele; Saccomandi, Paola; Lewis, Elfed; Kim, Taesung

    2016-01-01

    During recent decades, minimally invasive thermal treatments (i.e., Radiofrequency ablation, Laser ablation, Microwave ablation, High Intensity Focused Ultrasound ablation, and Cryo-ablation) have gained widespread recognition in the field of tumor removal. These techniques induce a localized temperature increase or decrease to remove the tumor while the surrounding healthy tissue remains intact. An accurate measurement of tissue temperature may be particularly beneficial to improve treatment outcomes, because it can be used as a clear end-point to achieve complete tumor ablation and minimize recurrence. Among the several thermometric techniques used in this field, fiber optic sensors (FOSs) have several attractive features: high flexibility and small size of both sensor and cabling, allowing insertion of FOSs within deep-seated tissue; metrological characteristics, such as accuracy (better than 1 °C), sensitivity (e.g., 10 pm·°C(-1) for Fiber Bragg Gratings), and frequency response (hundreds of kHz), are adequate for this application; immunity to electromagnetic interference allows the use of FOSs during Magnetic Resonance- or Computed Tomography-guided thermal procedures. In this review the current status of the most used FOSs for temperature monitoring during thermal procedure (e.g., fiber Bragg Grating sensors; fluoroptic sensors) is presented, with emphasis placed on their working principles and metrological characteristics. The essential physics of the common ablation techniques are included to explain the advantages of using FOSs during these procedures. PMID:27455273

  12. Fiber Optic Sensors for Temperature Monitoring during Thermal Treatments: An Overview

    PubMed Central

    Schena, Emiliano; Tosi, Daniele; Saccomandi, Paola; Lewis, Elfed; Kim, Taesung

    2016-01-01

    During recent decades, minimally invasive thermal treatments (i.e., Radiofrequency ablation, Laser ablation, Microwave ablation, High Intensity Focused Ultrasound ablation, and Cryo-ablation) have gained widespread recognition in the field of tumor removal. These techniques induce a localized temperature increase or decrease to remove the tumor while the surrounding healthy tissue remains intact. An accurate measurement of tissue temperature may be particularly beneficial to improve treatment outcomes, because it can be used as a clear end-point to achieve complete tumor ablation and minimize recurrence. Among the several thermometric techniques used in this field, fiber optic sensors (FOSs) have several attractive features: high flexibility and small size of both sensor and cabling, allowing insertion of FOSs within deep-seated tissue; metrological characteristics, such as accuracy (better than 1 °C), sensitivity (e.g., 10 pm·°C−1 for Fiber Bragg Gratings), and frequency response (hundreds of kHz), are adequate for this application; immunity to electromagnetic interference allows the use of FOSs during Magnetic Resonance- or Computed Tomography-guided thermal procedures. In this review the current status of the most used FOSs for temperature monitoring during thermal procedure (e.g., fiber Bragg Grating sensors; fluoroptic sensors) is presented, with emphasis placed on their working principles and metrological characteristics. The essential physics of the common ablation techniques are included to explain the advantages of using FOSs during these procedures. PMID:27455273

  13. NASA/GSFC reliability evaluation of high temperature fiber optic cables

    NASA Technical Reports Server (NTRS)

    Sharma, A. K.; Jacobs, G.

    1992-01-01

    A high temperature (200 C rating) fiber-optic cable of fluorocarbon, silica-based glass, and polyimide coating, 100-micron core was evaluated for Goddard Space Flight Center applications. Testing was performed to evaluate attenuation characteristics of the cables during environmental stresses and exposure to Co-60 gamma radiation. The cables passed environmental tests, but after irradiation failed the established delta limit of 3 dB at 10 krads for a wavelength of 850 nm and 100 krads for a wavelength of 1300 nm.

  14. Overview of Fiber Optic Sensor Technologies for Strain/Temperature Sensing Applications in Composite Materials

    PubMed Central

    Ramakrishnan, Manjusha; Rajan, Ginu; Semenova, Yuliya; Farrell, Gerald

    2016-01-01

    This paper provides an overview of the different types of fiber optic sensors (FOS) that can be used with composite materials and also their compatibility with and suitability for embedding inside a composite material. An overview of the different types of FOS used for strain/temperature sensing in composite materials is presented. Recent trends, and future challenges for FOS technology for condition monitoring in smart composite materials are also discussed. This comprehensive review provides essential information for the smart materials industry in selecting of appropriate types of FOS in accordance with end-user requirements. PMID:26784192

  15. Overview of Fiber Optic Sensor Technologies for Strain/Temperature Sensing Applications in Composite Materials.

    PubMed

    Ramakrishnan, Manjusha; Rajan, Ginu; Semenova, Yuliya; Farrell, Gerald

    2015-01-01

    This paper provides an overview of the different types of fiber optic sensors (FOS) that can be used with composite materials and also their compatibility with and suitability for embedding inside a composite material. An overview of the different types of FOS used for strain/temperature sensing in composite materials is presented. Recent trends, and future challenges for FOS technology for condition monitoring in smart composite materials are also discussed. This comprehensive review provides essential information for the smart materials industry in selecting of appropriate types of FOS in accordance with end-user requirements. PMID:26784192

  16. Improving Photovoltaic Energy Production with Fiber-Optic Distributed Temperature Sensing

    NASA Astrophysics Data System (ADS)

    Hausner, M. B.; Berli, M.

    2014-12-01

    The efficiency of solar photovoltaic (PV) generators declines sharply with increased temperatures. Peak solar exposure often occurs at the same time as peak temperatures, but solar PV installations are typically designed based on solar angle. In temperate areas, the peak temperatures may not be high enough to induce significant efficiency losses. In some of the areas with the greatest potential for solar development, however, summer air temperatures regularly reach 45 °C and PV panel temperatures exceed the air temperatures. Here we present a preliminary model of a PV array intended to optimize solar production in a hot and arid environment. The model begins with the diurnal and seasonal cycles in the angle and elevation of the sun, but also includes a meteorology-driven energy balance to project the temperatures of the PV panels and supporting structure. The model will be calibrated and parameterized using a solar array at the Desert Research Institute's (DRI) Renewable Energy Deployment and Display (REDD) facility in Reno, Nevada, and validated with a similar array at DRI's Las Vegas campus. Optical fibers will be installed on the PV panels and structural supports and interrogated by a distributed temperature sensor (DTS) to record the spatial and temporal variations in temperature. Combining the simulated panel temperatures, the efficiency-temperature relationship for the panels, and the known solar cycles at a site will allow us to optimize the design of future PV collectors (i.e., the aspect and angle of panels) for given production goals.

  17. Fiber Optics Technology.

    ERIC Educational Resources Information Center

    Burns, William E.

    1986-01-01

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

  18. Fiber optic chemical sensors

    NASA Astrophysics Data System (ADS)

    Jung, Chuck C.; McCrae, David A.; Saaski, Elric W.

    1998-09-01

    This paper provides a broad overview of the field of fiber optic chemical sensors. Several different types of fiber optic sensors and probes are described, and references are cited for each category discussed.

  19. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

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

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

    PubMed

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

    2015-03-21

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

  2. Temperature insensitive hysteresis free highly sensitive polymer optical fiber Bragg grating humidity sensor.

    PubMed

    Woyessa, Getinet; Nielsen, Kristian; Stefani, Alessio; Markos, Christos; Bang, Ole

    2016-01-25

    The effect of humidity on annealing of poly (methyl methacrylate) (PMMA) based microstructured polymer optical fiber Bragg gratings (mPOFBGs) and the resulting humidity responsivity are investigated. Typically annealing of PMMA POFs is done in an oven without humidity control around 80°C and therefore at low humidity. We demonstrate that annealing at high humidity and high temperature improves the performances of mPOFBGs in terms of stability and sensitivity to humidity. PMMA POFBGs that are not annealed or annealed at low humidity level will have a low and highly temperature dependent sensitivity and a high hysteresis in the humidity response, in particular when operated at high temperature. PMMA mPOFBGs annealed at high humidity show higher and more linear humidity sensitivity with negligible hysteresis. We also report how annealing at high humidity can blue-shift the FBG wavelength more than 230 nm without loss in the grating strength. PMID:26832503

  3. Two-color infrared thermometer for low-temperature measurement using a hollow glass optical fiber

    SciTech Connect

    Small, W.

    1997-02-28

    In the thermometer, radiation from a target is collected via a single 700 {mu}m-bore hollow glass optical fiber coated with a metallic/dielectric layer on the inner surface, simultaneously split into two paths and modulated by a Au-coated reflective chopper, and focused onto two thermoelectrically cooled mid-infrared HgCdZnTe photoconductors by 128.8 mm-radius Au-coated spherical mirrors. The photoconductors have spectral bandpasses of 2-6 {mu}m and 2.12 {mu}m, respectively. The modulated detector signals are recovered using lock- in amplification. The two signals are calibrated using a blackbody (emissivity=1) of known temperature, and exponential fits are applied to the two resulting voltage vs temperature curves. Using the two calibration equations, a computer algorithm calculates the temperature and emissivity of a target in real time, taking into account reflection of the background radiation field from the target surface.

  4. Hybrid optical fiber Fabry-Perot interferometer for simultaneous measurement of gas refractive index and temperature.

    PubMed

    Wang, Ruohui; Qiao, Xueguang

    2014-11-10

    We present a hybrid miniature optical fiber Fabry-Perot interferometer for simultaneous measurement of gas refractive index and temperature. The interferometer is fabricated by cascading two short sections of capillary tubes with different inner diameters. One extrinsic interferometer is based on the air gap cavity formed by the capillary tube with large diameter. Another section of capillary tube with small inner diameter performs as an intrinsic interferometer and also provides a channel enabling gas to enter and leave the extrinsic cavity freely. The experiment shows that the different dips or peaks in fringe exhibit different responses to the changes in gas refractive index and temperature. Owing to this feature, simultaneous measurement of the gas refractive index and temperature can be realized. PMID:25402996

  5. 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.

  6. A new noise suppression algorithm for optical fiber temperature surveillance of heavy oil thermal recovery well

    NASA Astrophysics Data System (ADS)

    Wang, Jiahuai; Han, Jisheng; Pan, Yong; Zhang, Min; Zou, Qilin; Xie, Shangran

    2011-11-01

    Pure silica core optical fiber is commonly used as the sensing fiber in Raman-backscatter distributed temperature sensors (DTS) in heavy oil thermal well. However the sensing signal collected from this type of fiber statistically belongs to nonstationary random process which cannot be effectively de-noised by simply applying conventional methods. To solve this problem, we develop a novel noise suppression algorithm by combining wavelet multi-scale analysis and moving grey model GM(1,1). The algorithm first applies wavelet de-noising in spatial domain of temperature profile to remove the high frequency noise, then uses moving GM(1,1) method to remove both high frequency and low frequency nonstationary noise in time domain. Autoregressive (AR) model and least square regression are used to optimize the forecasting parameters of GM(1,1). Finally the results of both domains are reconstructed to obtain the de-noised profile. Long-term field test was proposed on the Karamay oil field F11051 steam stimulation well, Xinjiang Province, China. Field test result shows that signal to noise ratio (SNR) is improved by 11dB using the algorithm.

  7. Demonstration of a Fiber Optic Regression Probe in a High-Temperature Flow

    NASA Technical Reports Server (NTRS)

    Korman, Valentin; Polzin, Kurt

    2011-01-01

    The capability to provide localized, real-time monitoring of material regression rates in various applications has the potential to provide a new stream of data for development testing of various components and systems, as well as serving as a monitoring tool in flight applications. These applications include, but are not limited to, the regression of a combusting solid fuel surface, the ablation of the throat in a chemical rocket or the heat shield of an aeroshell, and the monitoring of erosion in long-life plasma thrusters. The rate of regression in the first application is very fast, while the second and third are increasingly slower. A recent fundamental sensor development effort has led to a novel regression, erosion, and ablation sensor technology (REAST). The REAST sensor allows for measurement of real-time surface erosion rates at a discrete surface location. The sensor is optical, using two different, co-located fiber-optics to perform the regression measurement. The disparate optical transmission properties of the two fiber-optics makes it possible to measure the regression rate by monitoring the relative light attenuation through the fibers. As the fibers regress along with the parent material in which they are embedded, the relative light intensities through the two fibers changes, providing a measure of the regression rate. The optical nature of the system makes it relatively easy to use in a variety of harsh, high temperature environments, and it is also unaffected by the presence of electric and magnetic fields. In addition, the sensor could be used to perform optical spectroscopy on the light emitted by a process and collected by fibers, giving localized measurements of various properties. The capability to perform an in-situ measurement of material regression rates is useful in addressing a variety of physical issues in various applications. An in-situ measurement allows for real-time data regarding the erosion rates, providing a quick method for

  8. Specialty optical fibers: revisited

    NASA Astrophysics Data System (ADS)

    Romaniuk, Ryszard S.

    2011-10-01

    The paper contains description of chosen aspects of analysis and design of tailored optical fibers. By specialty optical fibers we understand here the fibers which have complex construction and which serve for the functional processing of optical signal rather than long distance transmission. Thus, they are called also instrumentation optical fibers. The following issues are considered: transmission properties, transformation of optical signal, fiber characteristics, fiber susceptibility to external reactions. The technology of tailored optical fibers offers a wider choice of the design tools for the fiber itself, and then various devices made from these fiber, than classical technology of communication optical fibers. The consequence is different fiber properties, nonstandard dimensions and different metrological problems. The price to be paid for wider design possibilities are bigger optical losses of these fibers and weaker mechanical properties, and worse chemical stability. These fibers find their applications outside the field of telecommunications. The applications of instrumentation optical fibers combine other techniques apart from the photonics ones like: electronic, chemical and mechatronic.

  9. Omnidirectional fiber optic tiltmeter

    DOEpatents

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

    1983-06-30

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

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

    SciTech Connect

    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 of 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 CO2 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

  11. Testing of Performance of Optical Fibers Under Irradiation in Intense Radiation Fields, When Subjected to Very High Temperatures

    SciTech Connect

    Blue, Thomas; Windl, Wolfgang; Dickerson, Bryan

    2013-01-03

    The primary objective of this project is to measure and model the performance of optical fibers in intense radiation fields when subjected to very high temperatures. This research will pave the way for fiber optic and optically based sensors under conditions expected in future high-temperature gas-cooled reactors. Sensor life and signal-to-noise ratios are susceptible to attenuation of the light signal due to scattering and absorbance in the fibers. This project will provide an experimental and theoretical study of the darkening of optical fibers in high-radiation and high-temperature environments. Although optical fibers have been studied for moderate radiation fluence and flux levels, the results of irradiation at very high temperatures have not been published for extended in-core exposures. Several previous multi-scale modeling efforts have studied irradiation effects on the mechanical properties of materials. However, model-based prediction of irradiation-induced changes in silica's optical transport properties has only recently started to receive attention due to possible applications as optical transmission components in fusion reactors. Nearly all damage-modeling studies have been performed in the molecular-dynamics domain, limited to very short times and small systems. Extended-time modeling, however, is crucial to predicting the long-term effects of irradiation at high temperatures, since the experimental testing may not encompass the displacement rate that the fibers will encounter if they are deployed in the VHTR. The project team will pursue such extended-time modeling, including the effects of the ambient and recrystallization. The process will be based on kinetic MC modeling using the concept of amorphous material consisting of building blocks of defect-pairs or clusters, which has been successfully applied to kinetic modeling in amorphized and recrystallized silicon. Using this procedure, the team will model compensation for rate effects, and the

  12. Optical Fiber Protection

    NASA Technical Reports Server (NTRS)

    1999-01-01

    F&S Inc. developed and commercialized fiber optic and microelectromechanical systems- (MEMS) based instrumentation for harsh environments encountered in the aerospace industry. The NASA SBIR programs have provided F&S the funds and the technology to develop ruggedized coatings and coating techniques that are applied during the optical fiber draw process. The F&S optical fiber fabrication facility and developed coating methods enable F&S to manufacture specialty optical fiber with custom designed refractive index profiles and protective or active coatings. F&S has demonstrated sputtered coatings using metals and ceramics and combinations of each, and has also developed techniques to apply thin coatings of specialized polyimides formulated at NASA Langley Research Center. With these capabilities, F&S has produced cost-effective, reliable instrumentation and sensors capable of withstanding temperatures up to 800? C and continues building commercial sales with corporate partners and private funding. More recently, F&S has adapted the same sensing platforms to provide the rapid detection and identification of chemical and biological agents

  13. A Fiber-Optic Sensor Using an Aqueous Solution of Sodium Chloride to Measure Temperature and Water Level Simultaneously

    PubMed Central

    Yoo, Wook Jae; Sim, Hyeok In; Shin, Sang Hun; Jang, Kyoung Won; Cho, Seunghyun; Moon, Joo Hyun; Lee, Bongsoo

    2014-01-01

    A fiber-optic sensor system using a multiplexed array of sensing probes based on an aqueous solution of sodium chloride (NaCl solution) and an optical time-domain reflectometer (OTDR) for simultaneous measurement of temperature and water level is proposed. By changing the temperature, the refractive index of the NaCl solution is varied and Fresnel reflection arising at the interface between the distal end of optical fiber and the NaCl solution is then also changed. We measured the modified optical power of the light reflected from the sensing probe using a portable OTDR device and also obtained the relationship between the temperature of water and the optical power. In this study, the water level was simply determined by measuring the signal difference of the optical power due to the temperature difference of individual sensing probes placed inside and outside of the water. In conclusion, we demonstrate that the temperature and water level can be obtained simultaneously by measuring optical powers of light reflected from sensing probes based on the NaCl solution. It is anticipated that the proposed fiber-optic sensor system makes it possible to remotely monitor the real-time change of temperature and water level of the spent fuel pool during a loss of power accident. PMID:25310471

  14. Fiber Optic Attenuators

    NASA Technical Reports Server (NTRS)

    1995-01-01

    Mike Buzzetti designed a fiber optic attenuator while working at Jet Propulsion Laboratory, intended for use in NASA's Deep Space Network. Buzzetti subsequently patented and received an exclusive license to commercialize the device, and founded Nanometer Technologies to produce it. The attenuator functions without introducing measurable back-reflection or insertion loss, and is relatively insensitive to vibration and changes in temperature. Applications include cable television, telephone networks, other signal distribution networks, and laboratory instrumentation.

  15. Calibrating Single-Ended Fiber-Optic Raman Spectra Distributed Temperature Sensing Data

    PubMed Central

    Hausner, Mark B.; Suárez, Francisco; Glander, Kenneth E.; van de Giesen, Nick; Selker, John S.; Tyler, Scott W.

    2011-01-01

    Hydrologic research is a very demanding application of fiber-optic distributed temperature sensing (DTS) in terms of precision, accuracy and calibration. The physics behind the most frequently used DTS instruments are considered as they apply to four calibration methods for single-ended DTS installations. The new methods presented are more accurate than the instrument-calibrated data, achieving accuracies on the order of tenths of a degree root mean square error (RMSE) and mean bias. Effects of localized non-uniformities that violate the assumptions of single-ended calibration data are explored and quantified. Experimental design considerations such as selection of integration times or selection of the length of the reference sections are discussed, and the impacts of these considerations on calibrated temperatures are explored in two case studies. PMID:22346676

  16. Investigation of aquifer-estuary interaction using wavelet analysis of fiber-optic temperature data

    USGS Publications Warehouse

    Henderson, R.D.; Day-Lewis, F. D.; Harvey, C.F.

    2009-01-01

    Fiber-optic distributed temperature sensing (FODTS) provides sub-minute temporal and meter-scale spatial resolution over kilometer-long cables. Compared to conventional thermistor or thermocouple-based technologies, which measure temperature at discrete (and commonly sparse) locations, FODTS offers nearly continuous spatial coverage, thus providing hydrologie information at spatiotemporal scales previously impossible. Large and information-rich FODTS datasets, however, pose challenges for data exploration and analysis. To date, FODTS analyses have focused on time-series variance as the means to discriminate between hydrologic phenomena. Here, we demonstrate the continuous wavelet transform (CWT) and cross-wavelet transform (XWT) to analyze FODTS in the context of related hydrologic time series. We apply the CWT and XWT to data from Waquoit Bay, Massachusetts to identify the location and timing of tidal pumping of submarine groundwater Copyright 2009 by the American Geophysical Union.

  17. The development of a fiber optic Raman temperature measurement system for rocket flows

    NASA Technical Reports Server (NTRS)

    De Groot, Wim A.

    1991-01-01

    A fiber-optic Raman diagnostic system for H2/O2 rocket flows is currently under development. This system is designed for measurements of temperature and major species concentration in the combustion chamber and part of the nozzle of a 100 Newton thrust rocket currently undergoing tests. This paper describes a measurement system based on the spontaneous Raman scattering phenomenon. An analysis of the principles behind the technique is given. Software is developed to measure temperature and major species concentration by comparing theoretical Raman scattering spectra with experimentally obtained spectra. Equipment selection and experimental approach are summarized. This experimental effort is part of a program, which is in progress, to evaluate Navier-Stokes based analyses for this class of rockets.

  18. Fiber optic sensing system for temperature and gas monitoring in coal waste pile combustion environments

    NASA Astrophysics Data System (ADS)

    Viveiros, D.; Ribeiro, J.; Ferreira, J.; Lopez-Albada, A.; Pinto, A. M. R.; Perez-Herrera, R. A.; Diaz, S.; Lopez-Gil, A.; Dominguez-Lopez, A.; Esteban, O.; Martin-Lopez, S.; Auguste, J.-L.; Jamier, R.; Rougier, S.; Silva, S. O.; Frazão, O.; Santos, J. L.; Flores, D.; Roy, P.; Gonzalez-Herraez, M.; Lopez-Amo, M.; Baptista, J. M.

    2015-09-01

    It is presented an optical fiber sensing system projected to operate in the demanding conditions associated with coal waste piles in combustion. Distributed temperature measurement and spot gas sensing are requirements for such a system. A field prototype has been installed and is continuously gathering data, which will input a geological model of the coal waste piles in combustion aiming to understand their dynamics and evolution. Results are presented on distributed temperature and ammonia measurement, being noticed any significant methane emission in the short time period considered. Carbon dioxide is also a targeted gas for measurement, with validated results available soon. The assessment of this technology as an effective and reliable tool to address the problem of monitoring coal waste piles in combustion opens the possibility of its widespread application in view of the worldwide presence of coal related fires.

  19. 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.

  20. 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.

  1. Real-time frequency domain temperature and oxygen sensor with a single optical fiber.

    PubMed

    Liao, S C; Xu, Z; Izatt, J A; Alcala, J R

    1997-11-01

    The combined excited-state phosphorescence life-times of an alexandrite crystal and platinum tetraphenylporphyrin Pt(TPP) in a single-fiber sensor are used to monitor temperature and oxygen concentration in the physiological range from 15-45 degrees C and 0-50% O2 with precision of 0.24 degree C and 0.15% O2 and accuracy of 0.28 degree C and 0.2% O2. A 500-micron cubic alexandrite crystal bound to the distal end of a 750-micron-diameter optical fiber core and the Pt(TPP) coated circumferentially with a length of 1 cm from the end of the same fiber are excited with pulsed super-bright blue LED light. This apparatus uses a 125-kHz sampler for data acquisition and frequency domain methods for signal processing. The instrument amplifies both the dc and ac components of the photomultiplier output and band limits the signal to 20 kHz. The fundamental frequency of the excitation is set to 488.3 Hz and the highest harmonic used is the 35th. This bandlimited signal is sampled and averaged over a few hundred cycles in the time domain. The frequency domain representation of the data is obtained by employing fast Fourier transform algorithms. The phase delay and the modulation ratio of each sampled harmonic are then computed. At least four log-spaced harmonic phases or modulations are averaged before decoding the two lifetimes of temperature and oxygen phosphorescent sensors. A component of zero lifetime is introduced to account for the excitation backscatter leakage through optical interference filters seen by the photodetector. Linear and second-order empirical polynomials are employed to compute the temperatures and oxygen concentrations from the inverse lifetimes. In the situation of constant oxygen concentration, the lifetime of Pt(TPP) changes with temperature but can be compensated using the measured temperature lifetime. The system drift is 0.24 degree C for the temperature measurement and 0.59% for the oxygen concentration measurement over 30 h of continuous operation

  2. Embedding Optical Fibers In Cast Metal Parts

    NASA Technical Reports Server (NTRS)

    Gibler, William N.; Atkins, Robert A.; Lee, Chung E.; Taylor, Henry F.

    1995-01-01

    Use of metal strain reliefs eliminates breakage of fibers during casting process. Technique for embedding fused silica optical fibers in cast metal parts devised. Optical fiber embedded in flange, fitting, or wall of vacuum or pressure chamber, to provide hermetically sealed feedthrough for optical transmission of measurement or control signals. Another example, optical-fiber temperature sensor embedded in metal structural component to measure strain or temperature inside component.

  3. Sealed fiber-optic bundle feedthrough

    DOEpatents

    Tanner, Carol E.

    2002-01-01

    A sealed fiber-optic bundle feedthrough by which a multitude of fiber-optic elements may be passed through an opening or port in a wall or structure separating two environments at different pressures or temperatures while maintaining the desired pressure or temperature in each environment. The feedthrough comprises a rigid sleeve of suitable material, a bundle of individual optical fibers, and a resin-based sealing material that bonds the individual optical fibers to each other and to the rigid sleeve.

  4. Optical Fiber Spectroscopy

    NASA Technical Reports Server (NTRS)

    Buoncristiani, A. M.

    1999-01-01

    This is the final report of work done on NASA Grant NAG-1-443. The work covers the period from July 1, 1992 to December 1, 1998. During this period several distinct but related research studies and work tasks were undertaken. These different subjects are enumerated below with a description of the work done on each of them. The focus of the research was the development of optical fibers for use as distributed temperature and stress sensors. The initial concept was to utilize the utilize the temperature and stress dependence of emission from rare earth and transition metal ions substitutionally doped into crystalline or glass fibers. During the course of investigating this it became clear that fiber Bragg gratings provided a alternative for making the desired measurements and there was a shift of research focus on to include the photo-refractive properties of germano-silicate glasses used for most gratings and to the possibility of developing fiber laser sources for an integrated optical sensor in the research effort. During the course of this work several students from Christopher Newport University and other universities participated in this effort. Their names are listed below. Their participation was an important part of their education.

  5. Fiber optic micro accelerometer

    DOEpatents

    Swierkowski, Steve P.

    2005-07-26

    An accelerometer includes a wafer, a proof mass integrated into the wafer, at least one spring member connected to the proof mass, and an optical fiber. A Fabry-Perot cavity is formed by a partially reflective surface on the proof mass and a partially reflective surface on the end of the optical fiber. The two partially reflective surfaces are used to detect movement of the proof mass through the optical fiber, using an optical detection system.

  6. The Fiber Optic Connection.

    ERIC Educational Resources Information Center

    Reese, Susan

    2003-01-01

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

  7. Advances In Optical Fiber Sensors

    NASA Astrophysics Data System (ADS)

    Cole, J. H.; Giallorenzi, T. G.; Bucaro, J. A.

    1981-07-01

    Over the past several years, a new non-communication optical fiber application has emerged. This application utilizes optical fibers for sensing. Initial interest centered around rate rotation sensing. Since that time, however, acoustic, magnetic, and temperature sensing utilizing optical fibers has evolved into a viable research effort with significant potential payoff. As an example, laboratory fiber optic acoustic sensors now rival the best sensitivity obtained with piezoelectric ceramics. These sensors possess a unique geometric versatility previously unavailable. In conjunction with the Defense Advanced Research Projects Agency (DARPA), the Navy has begun a Fiber Optic Sensor System (FOSS) program to develop associated technology necessary to realize these sensors. Substantial effort is ongoing at the Naval Research Laboratory (NRL) and other Navy laboratories with considerable contractual effort from universities and industry. This paper reviews the status of the FOSS program.

  8. Coating-free reflection technique for fiber-optic sensors based on multimode interference: A temperature sensing study

    NASA Astrophysics Data System (ADS)

    Taue, Shuji; Takahashi, Tsuyoshi; Fukano, Hideki

    2016-08-01

    A novel reflection technique for use in fiber-optic sensors is investigated and applied to a multimode interference structure. The reflectivity at a fiber end face is increased with two operations. Firstly, the light intensity is increased toward the periphery of the end-face by adjusting the fiber length, which is determined theoretically. Secondly, the fiber end-face is deformed into an ellipsoid by heating it with a gas torch. The deformed shape is characterized from microscopic images. The reflected light intensity is increased by more than 10 dB as a result of controlling the fiber length and deforming its end-face. Temperature sensing was performed using the reflection-type multimode interference structure immersed in temperature-controlled silicone oil. The resulting sensitivity was 0.028 °C for a 29.60 mm sensing region, achieved without using any reflection coating.

  9. Development of A Semiconductor Laser Based High Temperature Fine Thermal Energy Source in an Optical Fiber Tip for Clinical Applications

    NASA Astrophysics Data System (ADS)

    Fujimoto, Takahiro; Imai, Yusuke; Tei, Kazuyoku; Yamaguchi, Shigeru

    2013-05-01

    A new technique for generating high temperatures on the surface of an optical fiber is developed for medical applications using lower-power semiconductor lasers with output powers lower than 10 W. Using a power level of 4-6 W semiconductor laser with a pulse duration of 180 ms at a wavelength of 980 nm, a laser-coupled fiber tip was once processed to contain a certain amount of Ti with a depth of 100 µm from the tip surface so that the laser energy could be efficiently absorbed to be transferred to thermal energy. With consecutive laser pulse irradiation, the tip processed fiber (TP fiber) served as a reproducible fine heat source whose temperature was measured to be in excess 3100 K based on two-color thermometry. Processing of ceramic and niobium plate, which are hardly ablated with direct low power (6 W) irradiation, was successfully demonstrated by contacting the TP fiber excited with the same power.

  10. Continuous measurement of tympanic temperature with a new infrared method using an optical fiber.

    PubMed

    Shibasaki, M; Kondo, N; Tominaga, H; Aoki, K; Hasegawa, E; Idota, Y; Moriwaki, T

    1998-09-01

    The purpose of this study was to investigate the utility of an infrared tympanic thermometry by using an optical fiber for measuring tympanic temperature (Tty). In the head cooling and facial fanning tests during normothermia, right Tty measured by this method (infrared-Tty) and esophageal temperature (Tes) were not affected by decreased temple and forehead skin temperatures, suggesting that the infrared sensor in this system measured the infrared radiation from the tympanic membrane selectively. Eight male subjects took part in passive-heat-stress and progressive-exercise tests. No significant differences among infrared-Tty, the left Tty measured by thermistor (contact-Tty), and Tes were observed at rest or at the end of each experiment, and there was no significant difference in the increase in these core temperatures from rest to the end. Furthermore, there were no significant differences in the core temperature threshold at the onset of sweating and slope (the relationship of sweating rate vs. infrared-Tty and vs. contact-Tty). These results suggest that this method makes it possible to measure Tty accurately, continuously, and more safely. PMID:9729565

  11. Monolithic fiber optic sensor assembly

    SciTech Connect

    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.

  12. Temperature Compensation in Determining of Remazol Black B Concentrations Using Plastic Optical Fiber Based Sensor

    PubMed Central

    Chong, Su Sin; Aziz, A.R. Abdul; Harun, Sulaiman W.; Arof, Hamzah

    2014-01-01

    In this study, the construction and test of tapered plastic optical fiber (POF) sensors, based on an intensity modulation approach are described. Tapered fiber sensors with different diameters of 0.65 mm, 0.45 mm, and 0.35 mm, were used to measure various concentrations of Remazol black B (RBB) dye aqueous solutions at room temperature. The concentrations of the RBB solutions were varied from 0 ppm to 70 ppm. In addition, the effect of varying the temperature of the RBB solution was also investigated. In this case, the output of the sensor was measured at four different temperatures of 27 °C, 30 °C, 35 °C, and 40 °C, while its concentration was fixed at 50 ppm and 100 ppm. The experimental results show that the tapered POF with d = 0.45 mm achieves the best performance with a reasonably good sensitivity of 61 × 10−4 and a linearity of more than 99%. It also maintains a sufficient and stable signal when heat was applied to the solution with a linearity of more than 97%. Since the transmitted intensity is dependent on both the concentration and temperature of the analyte, multiple linear regression analysis was performed to combine the two independent variables into a single equation. The resulting equation was then validated experimentally and the best agreement between the calculated and experimental results was achieved by the sensor with d = 0.45 mm, where the minimum discrepancy is less than 5%. The authors conclude that POF-based sensors are suitable for RBB dye concentration sensing and, with refinement in fabrication, better results could be achieved. Their low fabrication cost, simple configuration, accuracy, and high sensitivity would attract many potential applications in chemical and biological sensing. PMID:25166498

  13. Fiber optic laser rod

    DOEpatents

    Erickson, G.F.

    1988-04-13

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

  14. An acceleration transducer based on optical fiber Bragging grating with temperature self-compensating function

    NASA Astrophysics Data System (ADS)

    Wang, Chuan; Lu, Qiyu; Ou, Jinping

    2013-04-01

    Along with the maturity and development of Optical Fiber Bragg Grating (OFBG) sensing technology, OFBG sensors with different functions have been developed and applied in large-scale engineering structure health monitoring and construction monitoring. In this paper, an acceleration transducer with a characteristic of temperature self-compensating is introduced. It is a cantilever structure model with equal strength beam, fixed with a mass block at the end of the beam, and two consecutive OFBGs are pasted on the upper and lower surface axis of the beam at the corresponding places. Because of the two OFBGs are near to each other, the wavelength changes caused by the environment temperature is the same. According to the temperature self-compensating principle and acceleration measurement principle developed in this paper, we can achieve the temperature self-compensating function of real acceleration measurement by simply calculating the test results. The experimental results show that this type of acceleration transducer has high sensitivity and stability and its measuring range can also be changed according to the practical requirements. This type of acceleration transducer is suitable for engineering structure acceleration measurement in different environment conditions.

  15. Multipoint Pressure and Temperature Sensing Fiber Optic Cable for Monitoring CO2 Sequestration

    SciTech Connect

    Challener, William

    2014-12-31

    This report describes the work completed on contract DE-FE0010116. The goal of this two year project was to develop and demonstrate in the laboratory a highly accurate multi-point pressure measurement fiber optic cable based on MEMS pressure sensors suitable for downhole deployment in a CO2 sequestration well. The sensor interrogator was also to be demonstrated in a remote monitoring system and environmental testing was to be completed to indicate its downhole survivability over a lengthy period of time (e.g., 20 years). An interrogator system based on a pulsed laser excitation was shown to be capable of multiple (potentially 100+) simultaneous sensor measurements. Two sensors packages were completed and spliced in a cable onto the same fiber and measured. One sensor package was subsequently measured at high temperatures and pressures in supercritical CO2, while the other package was measured prior and after being subjected to high torque stresses to mimic downhole deployment. The environmental and stress tests indicated areas in which the package design should be further improved.

  16. The influence of temperature to a refractive index sensor based on a macro-bending tapered plastic optical fiber

    NASA Astrophysics Data System (ADS)

    Teng, Chuan-xin; Yu, Fang-da; Jing, Ning; Zheng, Jie

    2016-09-01

    The temperature influence to a refractive index (RI) sensor based on a macro-bending tapered plastic optical fiber (POF) was investigated experimentally. The total temperature dependence loss (TDLtotal) and total temperature dependence RI deviation (TDRtotal) were measured at different temperature (10-60 °C) over an RI range of 1.33-1.41. The temperature dependence RI deviation of the sensor itself was obtained by subtracting the temperature dependence RI of measured liquid from TDRtotal. Therefore, the influence of temperature variation to the sensor was characterized and corrected.

  17. All-fiber-optic infrared multispectral radiometer for measurements of temperature and emissivity of graybodies at near-room temperature.

    PubMed

    Uman, Igor; Sade, Sharon; Gopal, Veena; Harrington, James A; Katzir, Abraham

    2004-04-01

    An all-fiber-optic infrared multispectral radiometer for measurements of temperature and emissivity of graybodies at near-room temperature was constructed. Different spectral regions in the radiometer were obtained by use of hollow glass waveguides (HGWs) as filters. Using HGWs instead of bulk filters was advantageous because each HGW can be used as two different spectral filters when a dual-band IR detector is used. In addition, HGWs are much cheaper than the bulk IR filters that are usually used in such applications. For one graybody with a mean emissivity of 0.71, the estimated mean errors obtained for sample temperature, ambient temperature, and sample emissivity for all measured temperatures were 0.50% (approximately 1.65 K), 0.48% (approximately 1.4 K), and 7.3% (approximately 0.052) respectively. For a second graybody with a mean emissivity of 0.8 the estimated mean errors were 0.35% (approximately 1.2 K), 0.48% (approximately 1.4 K), and 5.0% (approximately 0.04), respectively. PMID:15074410

  18. Cryogenic-temperature profiling of high-power superconducting lines using local and distributed optical-fiber sensors.

    PubMed

    Chiuchiolo, Antonella; Palmieri, Luca; Consales, Marco; Giordano, Michele; Borriello, Anna; Bajas, Hugues; Galtarossa, Andrea; Bajko, Marta; Cusano, Andrea

    2015-10-01

    This contribution presents distributed and multipoint fiber-optic monitoring of cryogenic temperatures along a superconducting power transmission line down to 30 K and over 20 m distance. Multipoint measurements were conducted using fiber Bragg gratings sensors coated with two different functional overlays (epoxy and poly methyl methacrylate (PMMA)) demonstrating cryogenic operation in the range 300-4.2 K. Distributed measurements exploited optical frequency-domain reflectometry to analyze the Rayleigh scattering along two concatenated fibers with different coatings (acrylate and polyimide). The integrated system has been placed along the 20 m long cryostat of a superconducting power transmission line, which is currently being tested at the European Organization for Nuclear Research (CERN). Cool-down events from 300-30 K have been successfully measured in space and time, confirming the viability of these approaches to the monitoring of cryogenic temperatures along a superconducting transmission line. PMID:26421547

  19. Intelligent process monitoring of multilayer ceramic actuators using high temperature optical fiber displacement sensors

    SciTech Connect

    Gunther, M.F.; Claus, R.O.; Ritter, A.; Tran, T.A.; Greene, J.A.

    1994-12-31

    The Fiber and Electro-Optics Research Center (FEORC) has developed a sensing technique for the intelligent processing of a multilayer ceramic actuator (MCA) elements manufactured by the AVX Corporation in Conway, SC. Presented are the results of the fiber optic strain sensor used to monitor the burnout of organic binders from a green actuator sample. The results establish the operation of the short gage length, low finesse Fabry-Perot interferometric strain sensor as a tool for intelligent processing of such ceramic actuator elements. Also presented is the method of sensor operation, and post processing results using the same sensor for tracking actuator performance and hysteresis.

  20. Infrared optical fibers

    NASA Astrophysics Data System (ADS)

    Drexhage, Martin G.; Moynihan, Cornelius T.

    1988-11-01

    The development of IR optical fibers for medical, laser, industrial, and telecommunications applications is discussed. IR studies of single and polycrystalline materials, chalcogenide glasses, and heavy-metal fluoride glasses are reviewed. It is suggested that heavy-metal fluoride glasses are the best prospects for obtaining optical losses lower than those in high-quality silica fibers.

  1. Multimode optical fiber

    DOEpatents

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

    2014-11-04

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

  2. Optical-fiber-coupled inferometric measurement of tympanic membrane temperature: a new diagnostic tool for acute otitis media

    NASA Astrophysics Data System (ADS)

    DeRowe, Ari; Ophir, Eyal; Sade, Sharon; Fishman, Gadi; Ophir, Dov; Grankin, Mila; Katzir, Abraham

    1998-07-01

    A novel infrared (IR) transparent optical fiber coupled to a hand held otoscope and a radiometer was constructed and used to measure the temperatures of the tympanic membrane (TM) and to distinguish between diseased and healthy middle ears. A greater temperature difference between TM readings was found when Acute Otitis Media (AOM) existed in one of the ears examined. This supports the hypothesis that acute inflammation of the middle ear will result in elevated local temperature when measured in such a way that the reading is taken only from the TM without interference of the external canal. The use of an optical fiber enabled temperature measurements of the TM with high spatial resolution eliminating the external ear canal interference. A small patient population was examined and the initial results were statistically significant. In the hands of the primary care physician, this tool would prevent misdiagnosis of AOM preventing indiscriminate use of antibiotics and avoiding complications by early diagnosis.

  3. Fiber optic attenuator

    NASA Technical Reports Server (NTRS)

    Buzzetti, Mike F. (Inventor)

    1994-01-01

    A fiber optic attenuator of the invention is a mandrel structure through which a bundle of optical fibers is wrapped around in a complete circle. The mandrel structure includes a flexible cylindrical sheath through which the bundle passes. A set screw on the mandrel structure impacts one side of the sheath against two posts on the opposite side of the sheath. By rotating the screw, the sheath is deformed to extend partially between the two posts, bending the fiber optic bundle to a small radius controlled by rotating the set screw. Bending the fiber optic bundle to a small radius causes light in each optical fiber to be lost in the cladding, the amount depending upon the radius about which the bundle is bent.

  4. Python fiber optic seal

    SciTech Connect

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

    1993-08-01

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

  5. Fiber optic hydrophone

    DOEpatents

    Kuzmenko, Paul J.; Davis, Donald T.

    1994-01-01

    A miniature fiber optic hydrophone based on the principles of a Fabry-Perot interferometer. The hydrophone, in one embodiment, includes a body having a shaped flexible bladder at one end which defines a volume containing air or suitable gas, and including a membrane disposed adjacent a vent. An optic fiber extends into the body with one end terminating in spaced relation to the membrane. Acoustic waves in the water that impinge on the bladder cause the pressure of the volume therein to vary causing the membrane to deflect and modulate the reflectivity of the Fabry-Perot cavity formed by the membrane surface and the cleaved end of the optical fiber disposed adjacent to the membrane. When the light is transmitted down the optical fiber, the reflected signal is amplitude modulated by the incident acoustic wave. Another embodiment utilizes a fluid filled volume within which the fiber optic extends.

  6. Fiber optic hydrophone

    DOEpatents

    Kuzmenko, P.J.; Davis, D.T.

    1994-05-10

    A miniature fiber optic hydrophone based on the principles of a Fabry-Perot interferometer is disclosed. The hydrophone, in one embodiment, includes a body having a shaped flexible bladder at one end which defines a volume containing air or suitable gas, and including a membrane disposed adjacent a vent. An optical fiber extends into the body with one end terminating in spaced relation to the membrane. Acoustic waves in the water that impinge on the bladder cause the pressure of the volume therein to vary causing the membrane to deflect and modulate the reflectivity of the Fabry-Perot cavity formed by the membrane surface and the cleaved end of the optical fiber disposed adjacent to the membrane. When the light is transmitted down the optical fiber, the reflected signal is amplitude modulated by the incident acoustic wave. Another embodiment utilizes a fluid filled volume within which the fiber optic extends. 2 figures.

  7. Effect of acclimation temperature on the axon and fiber diameter spectra and thickness of myelin of fibers of the optic nerve of goldfish.

    PubMed

    Matheson, D F; Roots, B I

    1988-07-01

    The optic nerves of common goldfish acclimated to 5 and 25 degrees C were fixed with glutaraldehyde in either phosphate buffer or PIPES with EGTA, post-fixed with osmium tetroxide, and examined by electron microscopy. The axon diameter spectra, from axons measured in electron micrographs and those measured on the electron microscope screen, differ noticeably with acclimation temperature. At the lower temperature, there is a definite shift toward the occurrence of larger fibers compared with the spectrum of the 25 degrees C fish. Although the number of fibers assessed is small compared with the total number in the goldfish nerve, these results confirm our previous study. These findings could be attributed to an increase in the number of new fibers during the acclimation to the higher temperature. We discuss this possibility and on the available evidence find it unlikely. Other changes in the axon and fiber are also seen with acclimation temperature. The axon to fiber diameter ratio, made directly from the electron micrographs, shows that axons from the nerves of the higher acclimation temperature fish possess consistently thicker myelin sheaths than are found for axons in nerves of the lower temperature fish. This finding is also in agreement with results obtained by us from measurements independent of each other. PMID:3391258

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

    NASA Astrophysics Data System (ADS)

    Zhang, Feng; Liu, Yueming; Lou, Jun

    2011-08-01

    methods mentioned above cannot satisfy the strain change monitoring of high temperature pressure piping. In this paper a novel method is presented using optical Fiber Bragg Grating sensor to carry on the real-time monitoring of the high temperature pressure piping surface strain change. firstly the stress and strain analysis of the high temperature pressure piping surface is given based on the established theoretical model, then optimized design and simulation is accomplished with computer ANSYS software. In the end a optimized set-up is put forward and discussed.

  9. Bidirectional fiber optic cable adapter

    NASA Astrophysics Data System (ADS)

    Linehan, M.; Gee, N. B.; Taylor, R.

    1983-02-01

    The technical objective of the BIFOCS program was to develop, build, and test a full-duplex single fiber, fiber optic link, operating in the 1.0 micron to 1.6 micron region, capable of transmitting 20 Mb/s data (10 to the -9th power BER) over a range of at least 10 km, with a goal of 15 km. The link MTBF goal was 5 X 10 to the 3rd power hours and operation over a temperature range of 0 to 50 C. The fiber optic cable consisted of sections not exceeding 2 km in length joined by commercially available dry fiber optic connectors. The system performed successfully at ambient temperature over 15 km of cable.

  10. Temperature Response of a Small Mountain Stream to Thunderstorm Cloud-Cover: Application of DTS Fiber-Optic Temperature Sensing

    NASA Astrophysics Data System (ADS)

    Thayer, D.; Klatt, A. L.; Miller, S. N.; Ohara, N.

    2014-12-01

    From a hydrologic point of view, the critical zone in alpine areas contains the first interaction of living systems with water which will flow to streams and rivers that sustain lowland biomes and human civilization. A key to understanding critical zone functions is understanding the flow of energy, and we can measure temperature as a way of looking at energy transfer between related systems. In this study we installed a Distributed Temperature Sensor (DTS) and fiber-optic cable in a zero-order stream at 9,000 ft in the Medicine Bow National Forest in southern Wyoming. We measured the temperature of the stream for 17 days from June 29 to July 16; the first 12 days were mostly sunny with occasional afternoon storms, and the last 5 experienced powerful, long-lasting storms for much of the day. The DTS measurements show a seasonal warming trend of both minimum and maximum stream temperature for the first 12 days, followed by a distinct cooling trend for the five days that experienced heavy storm activity. To gain insights into the timing and mechanisms of energy flow through the critical zone systems, we analyzed the timing of stream temperature change relative to solar short-wave radiation, and compared the stream temperature temporal response to the temporal response of soil temperature adjacent to the stream. Since convective thunderstorms are a dominant summer weather pattern in sub-alpine regions in the Rocky Mountains, this study gives us further insight into interactions of critical zone processes and weather in mountain ecosystems.

  11. Optical-fiber pyrometer positioning accuracy analysis

    NASA Astrophysics Data System (ADS)

    Tapetado, A.; García, E.; Díaz-Álvarez, J.; Miguélez, M. H.; Vazquez, C.

    2016-05-01

    The influence of the distance between the fiber end and the machined surface on temperature measurements in a two-color fiber-optic pyrometer is analyzed. The propose fiber-optic pyrometer is capable of measuring highly localized temperatures, while avoiding the use of lenses or fiber bundles, by using a standard graded index glass fiber OM1 with 62.5/125 core and cladding diameters. The fiber is placed very close to the target and below the tool insert. The output optical power at both wavelength bands is theoretically and experimentally analyzed for a temperature of 650°C at different fiber positions in a range of 2mm. The results show that there is no influence of the fiber position on the measured optical power and therefore, on the measured temperature.

  12. Fiber optic moisture sensor

    DOEpatents

    Kirkham, R.R.

    1984-08-03

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

  13. Fiber optic choline biosensor

    NASA Astrophysics Data System (ADS)

    Wang, Hong; Cao, Xiaojian; Jia, Ke; Chai, Xueting; Lu, Hua; Lu, Zuhong

    2001-10-01

    A fiber optic fluorescence biosensor for choline is introduced in this paper. Choline is an important neurotransmitter in mammals. Due to the growing needs for on-site clinical monitoring of the choline, much effect has been devoted to develop choline biosensors. Fiber-optic fluorescence biosensors have many advantages, including miniaturization, flexibility, and lack of electrical contact and interference. The choline fiber-optic biosensor we designed implemented a bifurcated fiber to perform fluorescence measurements. The light of the blue LED is coupled into one end of the fiber as excitation and the emission spectrum from sensing film is monitored by fiber-spectrometer (S2000, Ocean Optics) through the other end of the fiber. The sensing end of the fiber is coated with Nafion film dispersed with choline oxidase and oxygen sensitive luminescent Ru(II) complex (Tris(2,2'-bipyridyl)dichlororuthenium(II), hexahydrate). Choline oxidase catalyzes the oxidation of choline to betaine and hydrogen peroxide while consuming oxygen. The fluorescence intensity of oxygen- sensitive Ru(II) are related to the choline concentration. The response of the fiber-optic sensor in choline solution is represented and discussed. The result indicates a low-cost, high-performance, portable choline biosensor.

  14. UAS and DTS: Using Drones and Fiber Optics to Measure High Resolution Temperature of the Atmospheric Boundary Layer

    NASA Astrophysics Data System (ADS)

    Predosa, R. A.; Darricau, B.; Higgins, C. W.

    2015-12-01

    The atmospheric boundary layer (ABL) is the lowest part of the atmosphere that directly interacts with the planet's surface. The development of the ABL plays a vital role, as it affects the transport of atmospheric constituents such as air pollutants, water vapor, and greenhouse gases. Measurements of the processes in the ABL have been difficult due to the limitations in the spatial and temporal resolutions of the equipment as well as the height of the traditional flux tower. Recent advances in the unmanned aerial vehicle (UAV) and distributed temperature sensing (DTS) technologies have provided us with new tools to study the complex processes in ABL. We conducted a series of pioneering experiments in Eastern Oregon using a platform that combines UAV and DTS to collect data during morning and evening transitions in the ABL. The major components of this platform consists of a quad-copter, a DTS computer unit, and a set of customized fiber optic cables. A total of 75 flights were completed to investigate: (1) the capability of a duplexed fiber optic cable to reduce noise in the high spatial and temporal temperature measurements taken during the morning transition; (2) the possibility of using fiber optic cable as "wet bulb" thermometer to calculate relative humidity in the ABL at high spatial and temporal resolution. The preliminary results showed that using a fiber optic cable in a duplexed configuration with the UAV-DTS platform can effectively reduce noise level during the morning transition data collection. The customized "wet bulb" fiber optic cable is capable of providing information for the calculation of relative humidity in the ABL at unprecedented spatial and temporal resolutions. From this study, the UAV-DTS platform demonstrated great potential in collecting temperature data in the ABL and with the development of atmospheric sensor technologies, it will have more applications in the future.

  15. Infrared fiber optic materials

    NASA Technical Reports Server (NTRS)

    Feigelson, Robert S.

    1987-01-01

    The development of IR fiber optics for use in astronomical and other space applications is summarized. Candidate materials were sought for use in the 1 to 200 micron and the 200 to 1000 micron wavelength range. Synthesis and optical characterization were carried out on several of these materials in bulk form. And the fabrication of a few materials in single crystal fiber optic form were studied.

  16. Fiber optic distributed temperature sensing for the determination of air temperature

    NASA Astrophysics Data System (ADS)

    de Jong, S. A. P.; Slingerland, J. D.; van de Giesen, N. C.

    2015-01-01

    This paper describes a method to correct for the effect of solar radiation in atmospheric distributed temperature sensing (DTS) applications. By using two cables with different diameters, one can determine what temperature a zero diameter cable would have. Such a virtual cable would not be affected by solar heating and would take on the temperature of the surrounding air. With two unshielded cable pairs, one black pair and one white pair, good results were obtained given the general consensus that shielding is needed to avoid radiation errors (WMO, 2010). The correlations between standard air temperature measurements and air temperatures derived from both cables of colors had a high correlation coefficient (r2=0.99) and a RMSE of 0.38 °C, compared to a RMSE of 2.40 °C for a 3.0 mm uncorrected black cable. A thin white cable measured temperatures that were close to air temperature measured with a nearby shielded thermometer (RMSE of 0.61 °C). The temperatures were measured along horizontal cables with an eye to temperature measurements in urban areas, but the same method can be applied to any atmospheric DTS measurements, and for profile measurements along towers or with balloons and quadcopters.

  17. 1200°C high-temperature distributed optical fiber sensing using Brillouin optical time domain analysis.

    PubMed

    Xu, Pengbai; Dong, Yongkang; Zhou, Dengwang; Fu, Cheng; Zhang, Juwang; Zhang, Hongying; Lu, Zhiwei; Chen, Liang; Bao, Xiaoyi

    2016-07-20

    In this paper, up to 1100°C and 1200°C high-temperature distributed Brillouin sensing based on a GeO2-doped single-mode fiber (SMF) and a pure silica photonic crystal fiber (PCF) are demonstrated, respectively. The Brillouin frequency shift's (BFS) dependence on temperatures of the SMF and PCF agrees with a nonlinear function instead of a linear function, which is mainly due to the change of the acoustic velocity in a silica fiber. BFS hopping is observed in both kinds of fibers between 800°C-900°C in the first annealing process, and after that, the BFS exhibits stability and repeatability with a measurement accuracy as high as ±2.4°C for the SMF and ±3.6°C for the PCF. The BFS hopping is a highly temperature-dependent behavior, which means that a high temperature (>800°C) would accelerate this process to reach a stable state. After BFS hopping, both the SMF and PCF show good repeatability for temperatures higher than 1000°C without annealing. The process of coating burning of a silica fiber not only introduces a loss induced by micro-bending, but also imposes a compressive stress on the bare fiber, which contributes to an additional BFS variation at the temperature period of the coating burning (∼300°C-500°C). PMID:27463893

  18. Simultaneous measurement of refractive index and temperature with micro silica sphere cavity hybrid Fabry Perot optical fiber sensor

    NASA Astrophysics Data System (ADS)

    Ranjbar Naeini, O. R.; Latifi, H.; Zibaii, M. I.

    2015-09-01

    In this article, a novel Micro Silica Sphere Cavity Hybrid Fabry Perot optical fiber sensor is reported where refractive index (RI) and temperature can be simultaneously measured. The sensor is based on Micro Silica Sphere that was fabricated using a capillary tube. The micro silica sphere and optical fiber form a Hybrid Fabry Perot cavity. The temperature cross sensitivity of this sensor is small enough to be used for accurate RI measurement. The temperature sensitivity and RI sensitivity are -0.0028 dBm/ºC, -0.0044 dBm/ºC , -24.09 dBm/RIU and -20.6 dBm/RIU respectively, using two selected resonances.

  19. Phase-shifted helical long-period grating-based temperature-insensitive optical fiber twist sensors

    NASA Astrophysics Data System (ADS)

    Gao, Ran; Zhu, Yinian; Krishnaswamy, Sridhar; Yi, Jiang

    2015-03-01

    In smart structure monitoring, twist angle is one of the most critical mechanical parameters for infrastructure deterioration. A compact temperature-insensitive optical fiber twist sensor based on multi-phase-shifted helical long period fiber grating has been proposed and experimentally demonstrated in this paper. A multi-phase-shifted helical long period fiber grating is fabricated with a multi-period rotation technology. A π / 2 and a 3π / 2 phase shift is introduced in the helical long period fiber grating by changing the period. The helical pitch can be effectively changed with a different twist rate, which is measured by calculating the wavelength difference between two phase shift peaks. Although the wavelength of the phase shift peak also shifts with a change of the temperature, the wavelength difference between two phase shift peaks is constant due to two fixed phase shifts in the helical long period fiber grating, which is extremely insensitive to temperature change for the multi-phase-shifted helical long period fiber grating. The experimental results show that a sensitivity of up to 1.959 nm/(rad/m) is achieved.

  20. Advances in Using Fiber-Optic Distributed Temperature Sensing to Identify the Mixing of Waters

    NASA Astrophysics Data System (ADS)

    Briggs, M. A.; Day-Lewis, F. D.; Rosenberry, D. O.; Harvey, J. W.; Lane, J. W., Jr.; Hare, D. K.; Boutt, D. F.; Voytek, E. B.; Buckley, S.

    2014-12-01

    Fiber-optic distributed temperature sensing (FO-DTS) provides thermal data through space and time along linear cables. When installed along a streambed, FO-DTS can capture the influence of upwelling groundwater (GW) as thermal anomalies. The planning of labor-intensive physical measurements can make use of FO-DTS data to target areas of focused GW discharge that can disproportionately affect surface-water (SW) quality and temperature. Typical longitudinal FO-DTS spatial resolution ranges 0.25 to1.0 m, and cannot resolve small-scale water-column mixing or sub-surface diurnal fluctuations. However, configurations where the cable is wrapped around rods can improve the effective vertical resolution to sub-centimeter scales, and the pipes can be actively heated to induce a thermal tracer. Longitudinal streambed and high-resolution vertical arrays were deployed at the upper Delaware River (PA, USA) and the Quashnet River (MA, USA) for aquatic habitat studies. The resultant datasets exemplify the varied uses of FO-DTS. Cold anomalies found along the Delaware River steambed coincide with zones of known mussel populations, and high-resolution vertical array data showed relatively stable in-channel thermal refugia. Cold anomalies at the Quashnet River identified in 2013 were found to persist in 2014, and seepage measurements and water samples at these locations showed high GW flux with distinctive chemistry. Cable location is paramount to seepage identification, particularly in faster flowing deep streams such as the Quashnet and Delaware Rivers where steambed FO-DTS identified many seepage zones with no surface expression. The temporal characterization of seepage dynamics are unique to FO-DTS. However, data from Tidmarsh Farms, a cranberry bog restoration site in MA, USA indicate that in slower flowing shallow steams GW inflow affects surface temperature; therefore infrared imaging can provide seepage location information similar to FO-DTS with substantially less effort.

  1. Characterizing Groundwater Flowpaths with Fiber-Optic Distributed Temperature Sensing and Stable Isotopes

    NASA Astrophysics Data System (ADS)

    Peri, L.; Gryczkowski, L.; Zheng, Y.; Liu, J.; Wang, S.; Wu, B.; Yao, Y.; Huang, X.; Wei, H.; Liu, C.; Hu, Y.; Wu, X.; Yu, L.

    2012-12-01

    The Heihe River basin of Northern China experiences high demand for scarce water. The upper watershed consists of alpine mountains and glaciers while the lower watershed is the arid Gobi Desert. The middle basin is important for agriculture production and has an extensive network of irrigation canals that reduce flow in the Heihe River. The lower watershed therefore receives reduced flow which is impacting fragile desert environments. Sustainably managing water resources in the basin while allowing for continued agriculture requires enhanced understanding of watershed function and behavior. A hydrologic model is being developed of the middle basin to help address these issues. The identification of groundwater and surface water interactions is an important component for an accurate model. Fiber-optic Distributed Temperature Sensing (DTS) is being used in 2012 to help identify these processes. Stable isotope differences (deuterium and O-18) are also being used in areas of potential groundwater discharge identified by DTS to improve understanding of flowpaths within the watershed. This interactive study promotes future sustainable water resource management to restore desert ecosystems.

  2. Machine Tests Optical Fibers In Flexure

    NASA Technical Reports Server (NTRS)

    Darejeh, Hadi; Thomas, Henry; Delcher, Ray

    1993-01-01

    Machine repeatedly flexes single optical fiber or cable or bundle of optical fibers at low temperature. Liquid nitrogen surrounds specimen as it is bent back and forth by motion of piston. Machine inexpensive to build and operate. Tests under repeatable conditions so candidate fibers, cables, and bundles evaluated for general robustness before subjected to expensive shock and vibration tests.

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

    NASA Astrophysics Data System (ADS)

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

    2011-12-01

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

  4. A miniature fiber-optic sensor for high-resolution and high-speed temperature sensing in ocean environment

    NASA Astrophysics Data System (ADS)

    Liu, Guigen; Han, Ming; Hou, Weilin; Matt, Silvia; Goode, Wesley

    2015-05-01

    Temperature measurement is one of the key quantifies in ocean research. Temperature variations on small and large scales are key to air-sea interactions and climate change, and also regulate circulation patterns, and heat exchange. The influence from rapid temperature changes within microstructures are can have strong impacts to optical and acoustical sensor performance. In this paper, we present an optical fiber sensor for the high-resolution and high-speed temperature profiling. The developed sensor consists of a thin piece of silicon wafer which forms a Fabry-Pérot interferometer (FPI) on the end of fiber. Due to the unique properties of silicon, such as large thermal diffusivity, notable thermo-optic effects and thermal expansion coefficients of silicon, the proposed sensor exhibits excellent sensitivity and fast response to temperature variation. The small mass of the tiny probe also contributes to a fast response due to the large surface-tovolume ratio. The high reflective index at infrared wavelength range and surface flatness of silicon endow the FPI a spectrum with high visibilities, leading to a superior temperature resolution along with a new data processing method developed by us. Experimental results indicate that the fiber-optic temperature sensor can achieve a temperature resolution better than 0.001°C with a sampling frequency as high as 2 kHz. In addition, the miniature footprint of the senor provide high spatial resolutions. Using this high performance thermometer, excellent characterization of the realtime temperature profile within the flow of water turbulence has been realized.

  5. Design of a radiation-hard optical fiber Bragg grating temperature sensor

    NASA Astrophysics Data System (ADS)

    Gusarov, Andrei I.; Starodubov, Dmitry S.; Berghmans, Francis; Deparis, Olivier; Defosse, Yves; Fernandez, Alberto F.; Decreton, Marc C.; Megret, Patrice; Blondel, Michel

    1999-12-01

    Optical fiber sensors (OFSs) offer numerous advantages, which include immunity to electromagnetic interference, intrinsic safety, small size, a possibly high sensitivity, multiplexing capabilities, and the possibility of remote interrogation. However, OFSs have a relatively low penetration in the commercial market, which is still dominated by standard electromechanical sensors. Nuclear environments are an example where particular OFSs might have a distinct superiority in the competition, but the feasibility of using OFSs in radiation environments still needs to be assessed. In the present paper we report on irradiation experiments performed to provide a sound basis for the design of a fiber Bragg grating based sensor capable to operate even under high total dose exposure.

  6. Modulated FT- Raman Fiber-Optic Spectroscopy: A technique for Remotely Monitoring High-Temperature Reactions in Real-Time

    NASA Technical Reports Server (NTRS)

    Cooper, John B.; Wise, Kent L.; Jensen, Brian J.

    1997-01-01

    A modification to a commercial FT-Raman spectrometer is presented for the elimination of thermal backgrounds in FT-Raman spectra. The modification involves the use of a mechanical chopper to modulate the CW laser, remote collection of the signal via fiber optics, and connection of a dual-phase digital signal processor lock-in amplifier between the detector and the spectrometer's collection electronics to demodulate and filter the optical signals. The resulting modulated FT-Raman fiber-optic spectrometer is capable of completely eliminating thermal backgrounds at temperatures exceeding 370 C. In addition, the signal/noise of generated Raman spectra is greater than for spectra collected with the conventional FT-Raman under identical conditions and incident laser power. This is true for both room-temperature and hot samples. The method allows collection of data using preexisting spectrometer software. The total cost of the modification (excluding fiber optics) is approximately $3000 and requires less than 2 h to implement. This is the first report of Fr-Raman spectra collected at temperatures in excess of 300 C in the absence of thermal backgrounds.

  7. Fiber optic communication links

    SciTech Connect

    Meyer, R. H.

    1980-01-01

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

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

    SciTech Connect

    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 fiber optic fluorescence spectrometry. Fiber optic spectrometric techniques have been developed for investigating the optical properties of these sol-gel derived materials prepared as porous optical fibers or as coatings on the surface of silica optical fibers. Optical and electron microscopic techniques have been used to observe the microstructure, such as pore size, pore shape, sensing agent distribution, of sol-gel derived material, as well as the size and morphology of nanometer metal particle doped in sol-gel derived porous silica, the nature of coating of sol-gel derived materials on silica optical fiber surface. In addition, the chemical reactions of metal ion, nanostructured semiconductor metal oxides and nanometer sized metal particles with gas components at room temperature and high temperatures have also been investigated with fiber optic spectrometric methods. Three classes of fiber optic sensors have been developed based on the thorough investigation of sol-gel chemistry and sol-gel derived materials. The first group of fiber optic sensors uses porous silica optical fibers doped with metal ions or metal oxide as transducers for sensing trace NH{sub 3} and H{sub 2}S in high temperature gas samples. The second group of

  9. Splicing Efficiently Couples Optical Fibers

    NASA Technical Reports Server (NTRS)

    Lutes, G. F.

    1985-01-01

    Method of splicing single-mode optical fibers results in very low transmission losses through joined fiber ends. Coupling losses between joined optical-fiber ends only 0.1 dB. Method needs no special operator training.

  10. Thermal properties of a fiber-optic radiation sensor for measuring gamma-rays in high-temperature conditions

    NASA Astrophysics Data System (ADS)

    Jeon, Dayeong; Yoo, Wook Jae; Shin, Sang Hun; Hong, Seunghan; Sim, Hyeok In; Kim, Seon Geun; Jang, Jae Seok; Jang, Kyoung Won; Lee, Bongsoo; Park, Byung Gi; Moon, Joo Hyun

    2015-01-01

    A fiber-optic radiation sensor (FORS) was fabricated using a cerium-doped silicate-yttriumlutetium (LYSO:Ce) scintillator crystal and a silica optical fiber (SOF) to measure gamma-rays accurately in elevated temperature conditions. Throughout this study, a LYSO:Ce crystal was employed as a sensing material of the FORS due to its high light yield (32,000 photons/MeV), fast decay time (≤ 47 ns) and high detection efficiency. Although the LYSO:Ce crystal has many desirable qualities, the thermoluminescence (TL) should be eliminated by using a heat annealing process because the light yield of the LYSO:Ce crystal varies with its TL. In this study, therefore, we obtained the TL curve of the LYSO:Ce crystal by increasing the temperature up to 280 ℃, and we demonstrated that almost all of the TL of the LYSO:Ce crystal was eliminated by the heat annealing process.