The development and performance of a temperature optical fibre sensor is presented in the article. It is based on fluorescence lifetime measurement, exploiting a simple digital signal processing scheme for on-line fluorescence lifetime determination. Experimental implementation of the sensor was preceded by a numerical ray tracing Monte Carlo optimisation of probe collection efficiency. It was shown that one-fibre probes are a preferred alternative from a collection efficiency perspective. Two- and multiple fibre probes can be optimised by proper construction to achieve several times higher efficiency than previously reported probes. Model and modified digital lock-in signal processing scheme were experimentally confirmed by a set of measurements, using alexandrite crystal as a sensing element, with HeNe laser source for excitation. Accuracy of ±0.3 K was achieved in the 20÷90 °C temperature range with almost basic equipment.
Improved probe geometry and detection scheme for fluorescence lifetime based temperature optical sensor
A. Kobe, A. Babnik, D. Kuzman, I. Bajsič, J. Možina; October 14–18, 2018. "Improved probe geometry and detection scheme for fluorescence lifetime based temperature optical sensor." Proceedings of the International Congress on Applications of Lasers & Electro-Optics. ICALEO® ‘96: Proceedings of the Lasers and Electro-Optics for Automotive Manufacturing Conference. Orlando, FL, USA. (pp. pp. E155-E162). ASME. https://doi.org/10.2351/1.5059075
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