The University of Southampton
University of Southampton Institutional Repository

Quasi-distributed optical fibre strain sensors

Quasi-distributed optical fibre strain sensors
Quasi-distributed optical fibre strain sensors
This thesis presents for the first time two complementary techniques to monitor the optical path length in optical fibre over both long and short sensing lengths. Both techniques may be used to measure the physical environment of the optical fibre, in particular strain and temperature, and are suitable for multiplexed operation.

Signal-to-noise analysis shows that current optical time domain reflectometry (OTDR) systems do not fully exploit the spatial resolution theoretically available. A new OTDR technique exploits the theoretical findings to monitor the range of reflective markers in an optical fibre. Measuring strain in fibre sections of several metres is demonstrated. 100µm spatial resolution has been achieved with a pulse duration equivalent to 1 m fibre length and within one second measurement time.

The first fibre Bragg grating interrogation system using an acousto-optic tunable filter (AOTF) is described. The interrogation system locks the AOTF wavelength to the wavelength of a selected grating. Measuring the frequency of the AOTF control signal provides an accurate measurement of the grating wavelength. A detailed system analysis is presented to enable the optimisation of system parameters. A wavelength resolution corresponding to 0.4 microstrain is achieved within 0.1sec measurement time, close to the resolution predicted by the system model. This technique allows the use of fibre gratings as sensors for the measurement of both quasi-static and dynamic strains.

The combination of the two systems facilitate the utilisation of optical fibre to monitor a structure both over a few metres and at critical points. Both sensor types offer new measurement possibilities as embedded structure monitors, for example for in-service health and usage monitoring or as nerves for active control of smart structures.
University of Southampton
Geiger, Harald
f19c4598-aea4-48c8-a252-f392c89ab18b
Geiger, Harald
f19c4598-aea4-48c8-a252-f392c89ab18b
Dakin, John
04891b9b-5fb5-4245-879e-9e7361adf904

Geiger, Harald (1995) Quasi-distributed optical fibre strain sensors. University of Southampton, Faculty of Engineering and Applied Science, Doctoral Thesis, 151pp.

Record type: Thesis (Doctoral)

Abstract

This thesis presents for the first time two complementary techniques to monitor the optical path length in optical fibre over both long and short sensing lengths. Both techniques may be used to measure the physical environment of the optical fibre, in particular strain and temperature, and are suitable for multiplexed operation.

Signal-to-noise analysis shows that current optical time domain reflectometry (OTDR) systems do not fully exploit the spatial resolution theoretically available. A new OTDR technique exploits the theoretical findings to monitor the range of reflective markers in an optical fibre. Measuring strain in fibre sections of several metres is demonstrated. 100µm spatial resolution has been achieved with a pulse duration equivalent to 1 m fibre length and within one second measurement time.

The first fibre Bragg grating interrogation system using an acousto-optic tunable filter (AOTF) is described. The interrogation system locks the AOTF wavelength to the wavelength of a selected grating. Measuring the frequency of the AOTF control signal provides an accurate measurement of the grating wavelength. A detailed system analysis is presented to enable the optimisation of system parameters. A wavelength resolution corresponding to 0.4 microstrain is achieved within 0.1sec measurement time, close to the resolution predicted by the system model. This technique allows the use of fibre gratings as sensors for the measurement of both quasi-static and dynamic strains.

The combination of the two systems facilitate the utilisation of optical fibre to monitor a structure both over a few metres and at critical points. Both sensor types offer new measurement possibilities as embedded structure monitors, for example for in-service health and usage monitoring or as nerves for active control of smart structures.

Text
Geiger 1995 thesis 960T - Version of Record
Restricted to Repository staff only
Available under License University of Southampton Thesis Licence.

More information

Published date: April 1995
Organisations: University of Southampton, Optoelectronics Research Centre

Identifiers

Local EPrints ID: 399104
URI: http://eprints.soton.ac.uk/id/eprint/399104
PURE UUID: 3e909fab-feef-44f3-b74b-4289c82d915b

Catalogue record

Date deposited: 15 Sep 2016 15:53
Last modified: 12 Feb 2020 17:35

Export record

Download statistics

Downloads from ePrints over the past year. Other digital versions may also be available to download e.g. from the publisher's website.

View more statistics

Atom RSS 1.0 RSS 2.0

Contact ePrints Soton: eprints@soton.ac.uk

ePrints Soton supports OAI 2.0 with a base URL of http://eprints.soton.ac.uk/cgi/oai2

This repository has been built using EPrints software, developed at the University of Southampton, but available to everyone to use.

We use cookies to ensure that we give you the best experience on our website. If you continue without changing your settings, we will assume that you are happy to receive cookies on the University of Southampton website.

×