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Studies of measurement techniques for indirect chemical sensing based on fluorescence spectroscopy and applications for fibre-optic sensors

Record type: Thesis (Doctoral)

This thesis describes experimental and theoretical studies of interrogation systems for determining fluorescent decays of order a few microseconds. The studies have enabled optimised design of interrogators for sensing oxygen using a fluorescent polymer encapsulated ruthenium complex. Two basic interrogation methods were explored, using blue LED excitation.
The Rapid Lifetime Detection (RLD) scheme, a fluorescence interrogation method based on direct interrogation of the decay curve following pulsed excitation was generalised, and a novel method for optimising measurement precision derived. The effect of background light on the optimum was quantified. Dissolved (aqueous) oxygen concentration was measured to a precision of 1 part per billion using a 1 second response time (the peak fluorescence power was only 12.5±0.5pW).
A second interrogation method, where the phase delay between an intensity modulated excitation source and the resultant fluorescence is processed to make measurements, was for the first time, fully analysed for measurement of exponential decays. When measuring fluorescence lifetimes in the range 2.9-3.3µs, a precision of 2.3 x 10-10 s Hz-0.5 was achieved. (The peak fluorescence power was 500±25pW).
A novel combination of ruby optical temperature sensor insert and oxygen sensing layer was demonstrated as a simultaneous temperature and oxygen sensor.
A new fluorescence calibration standard consisting of thermally stabilised titanium-doped sapphire sample was constructed to calibrate and test the indicators.
This work was sponsored by a BRITE EuRam European project, which helped determine the priorities of the research.

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Citation

Austin, Edward Alfred Denzil (2002) Studies of measurement techniques for indirect chemical sensing based on fluorescence spectroscopy and applications for fibre-optic sensors University of Southampton, Optoelectronic Research Centre, Doctoral Thesis , 198pp.

More information

Published date: September 2002
Organisations: University of Southampton, Optoelectronics Research Centre

Identifiers

Local EPrints ID: 50196
URI: http://eprints.soton.ac.uk/id/eprint/50196
PURE UUID: 1e9009a5-c7b9-4fa8-8fac-1e018847cc35

Catalogue record

Date deposited: 01 Feb 2008
Last modified: 17 Jul 2017 14:53

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Contributors

Author: Edward Alfred Denzil Austin
Thesis advisor: John Dakin

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