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Proceedings Paper

Cr:YAG fluorescence decay for optical-fiber temperature sensors
Author(s): Vito C. Fernicola; Luigi Crovini
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Paper Abstract

The fluorescent decay time of Cr:YAG single crystals has been determined from room temperature to 300 degree(s)C in order to develop optical-fiber temperature sensors. The sensing crystal was placed at the common end of a bifurcated optical fiber with the two legs connected to the excitation source and to the photodetector, respectively. A 636-nm laser diode pulsed excitation was used to stimulate the emission of the sensitive material and the observed decay was related to the fluorescent lifetime. The absolute fluorescence lifetime was estimated by means of an exponential-decay model, which included baseline offset and noise, to within 0.2%. The calibration and estimation processes were repeated with four different Cr:YAG crystals in order to evaluate the intrinsic repeatability of the material in view of realizing a multi-probe optical-fiber thermometer with full sensor interchangeability. A two- level kinetic model was applied in order to derive the decay-time-versus-temperature curve. The results show that this model fits the experimental data with a standard error of the estimate of 1.6 microsecond(s) , that is comparable with experimental uncertainty. As a consequence of the modeling results we predict that, with the described technique, the upper temperature limit of a single probe can be extended to 400 degree(s)C with a measurement error to within +/- 1 degree(s)C.

Paper Details

Date Published: 9 March 1994
PDF: 6 pages
Proc. SPIE 2070, Fiber Optic and Laser Sensors XI, (9 March 1994); doi: 10.1117/12.169930
Show Author Affiliations
Vito C. Fernicola, Istituto di Metrologia--CNR (Italy)
Luigi Crovini, Istituto di Metrologia--CNR (Italy)


Published in SPIE Proceedings Vol. 2070:
Fiber Optic and Laser Sensors XI
Ramon P. DePaula, Editor(s)

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