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Proceedings Paper

Characterization of a quasi-distributed optical fiber chemical sensor
Author(s): Peter A. Wallace; Yatao Yang; Michael Campbell; Sheila Smith
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Paper Abstract

Techniques for distributed optical fiber chemical sensor development were investigated and a model system for pH measurement was developed and, as a result, discrete, distributed signals were obtained. Fluorescein sodium was chosen as a pH indicator for this work because of its well known properties and high fluorescent intensity. A low temperature sol-gel glass manufacturing process was utilized to immobilize the indicator onto the optical fiber core. Thin (approximately 1 micrometer) porous glass films were deposited on the surface of the optical fiber core with indicator molecules entrapped in the matrix. An OTDR technique was employed to obtain the signal at specific positions along the fiber. A dye laser, pumped by a N2 laser, produced blue light pulses at 440 nm which were launched into a 1 multiplied by 2 optical fiber coupler. A fiber with eight sensitive sections was splice to a 50:50 coupler. The indicator molecules were excited by the blue light via the evanescent wave. Part of the fluorescent light from the indicator molecules was coupled back into the fiber and transmitted back to the coupler. A fast PMT tube was attached to the other arm of the 1 by 2 coupler to detect the fluorescent light. Results were obtained for solutions of various pH value. The system appears to have potential for applications in environmental and safety monitoring.

Paper Details

Date Published: 27 November 1996
PDF: 6 pages
Proc. SPIE 2838, Distributed and Multiplexed Fiber Optic Sensors VI, (27 November 1996); doi: 10.1117/12.259794
Show Author Affiliations
Peter A. Wallace, Glasgow Caledonian Univ. (United Kingdom)
Yatao Yang, Glasgow Caledonian Univ. (United Kingdom)
Michael Campbell, Glasgow Caledonian Univ. (United Kingdom)
Sheila Smith, Glasgow Caledonian Univ. (United Kingdom)


Published in SPIE Proceedings Vol. 2838:
Distributed and Multiplexed Fiber Optic Sensors VI
Alan D. Kersey; John P. Dakin, Editor(s)

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