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31 August 2000 Spontaneous Brillouin-based distributed temperature fiber sensor with 35-cm spatial resolution
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Proceedings Volume 4074, Applications of Optical Fiber Sensors; (2000)
Event: Symposium on Applied Photonics, 2000, Glasgow, United Kingdom
Certain distributed sensing applications require sub-meter spatial resolution accuracy, and there is interest as to whether the Brillouin linewidth ultimately limits the spatial resolution that can be achieved. We present a single-ended, spontaneous Brillouin-based distributed temperature fiber sensor with measurements operating with a spatial accuracy of 35 cm. The sensor consists of two main components, a laser source to generate the Brillouin backscattered signal and a low cost filtering system which comprises an all-fiber Mach-Zehnder interferometer connected to a InGaAs detector and computer based averaging system. The sensing fiber was 1 km in total, consisting of three sections of conventional single-mode fiber spliced together with lengths of 600 m, 200 m and 200 m respectively. The second drum was at 67 degree(s)C, an increase of 44 degree(s)C from the two other drums at room temperature of 23 degree(s)C. The results show a rise in the Brillouin signal in the heated section. To take absolute measurements independent of fiber attenuation and localized splice/bend losses, the Brillouin signal has to be referenced to the Rayleigh backscattered signal that is independent of temperature fluctuations. The ratio of the Brillouin and Rayleigh signals (Landau-Placzek ratio) provides a temperature dependent signal which is corrected for splice/bend losses and fiber attenuation.
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Huai H. Kee, Gareth P. Lees, and Trevor P. Newson "Spontaneous Brillouin-based distributed temperature fiber sensor with 35-cm spatial resolution", Proc. SPIE 4074, Applications of Optical Fiber Sensors, (31 August 2000);

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