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Real-time distributed temperature gradient sensing using amplitude-based C-OTDR and sensing fiber with inscribed scattering dots
Author(s): K. Hicke; S. Chruscicki; K. Krebber
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Paper Abstract

We present a technique for distributed temperature gradient sensing in real-time along an optical fiber utilizing simple amplitude-based direct-detection coherent optical time domain reflectometry (C-OTDR) and a special sensing fiber. Our technique enables us to determine phase changes or low-frequency variations of the C-OTDR signal stemming from temperature variations. The distinct feature of the used sensing fiber is its structuring with equidistant strongly scattering dots. Consecutive pairs of these scatterers form the dominant local interferometers, effectively overwriting the otherwise highly nonlinear transfer function of common optical fiber. This enables a quasi-phase-resolved evaluation of perturbation responses originating from temperature changes at sensor positions between the scatterers. Using our method, we show the measurement of a nonlinear temperature transient from a heating process with a maximum temperature gradient of 0.8°C over 20 s and a total temperature increase of 28.4°C. This method requires almost no post-processing and can be used for simultaneous distributed vibration sensing (DVS) and quantification of local temperature gradients in a single fiber, e.g., for the use in condition monitoring of infrastructure or industrial installations.

Paper Details

Date Published: 28 August 2019
PDF: 4 pages
Proc. SPIE 11199, Seventh European Workshop on Optical Fibre Sensors, 1119920 (28 August 2019); doi: 10.1117/12.2539925
Show Author Affiliations
K. Hicke, Bundesanstalt für Materialforschung und -prüfung (Germany)
S. Chruscicki, Bundesanstalt für Materialforschung und -prüfung (Germany)
K. Krebber, Bundesanstalt für Materialforschung und -prüfung (Germany)


Published in SPIE Proceedings Vol. 11199:
Seventh European Workshop on Optical Fibre Sensors
Kyriacos Kalli; Sinead O. O'Keeffe; Gilberto Brambilla, Editor(s)

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