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Proceedings Paper

Digital signal processing for fluorescence-based fiber optic temperature sensor
Author(s): Chunhai Hu; Yutian Wang
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Paper Abstract

The monitoring of the fluorescence lifetime of selected materials has been one of the more successful schemes in optical fiber temperature sensing. In principle, both the rise of the fluorescent signal at constant excitation and its decay are described by a first-order exponential, where the time constant ? is a function of the temperature. However few corrections must be introduced to account for instrumental contributions resulting in a baseline offset B, noise and radiation leakage from the excitation source into the detection channel. These corrections can be better applied by means of a digital signal processing circuit. The system uses modified digital phase sensitive detection with phase locked to a fixed value and the modulation period tracking the measured lifetime. It can compensate for correlated and uncorrelated offsets of the decay signal and to work with very low signal-to-noise ratio. The test results give a typical resolution of 0. 1 % for decay. Such a system has been applied to measuring the fluorescence decay time of a chromium-doped YAG crystal used as s sensing element of a optical fiber thermometer The calibration of the thermometer has shown a temperature resolution of 0. 1 0C from OC to 100 0C.

Paper Details

Date Published: 9 September 2002
PDF: 3 pages
Proc. SPIE 4920, Advanced Sensor Systems and Applications, (9 September 2002); doi: 10.1117/12.481954
Show Author Affiliations
Chunhai Hu, Yanshan Univ. (China)
Yutian Wang, Yanshan Univ. (China)

Published in SPIE Proceedings Vol. 4920:
Advanced Sensor Systems and Applications
Yun-Jiang Rao; Julian D. C. Jones; Hiroshi Naruse; Robert I. Chen, Editor(s)

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