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Design and application of a distributed optical fibre dynamic strain sensor

Design and application of a distributed optical fibre dynamic strain sensor
Design and application of a distributed optical fibre dynamic strain sensor
Over the past two decades, distributed optical fibre sensors (DOFS) based on Brillouin and Raman scattering have been extensively studied. As a result, a wide range of distributed temperature and strain sensors with different sensing range and accuracy levels have been developed. However, due to the weak nature of Brillouin and Raman scattering, most of the research in this field has been focused on DC or quasi-DC measurement of temperature and strain. On the other hand, the Rayleigh-based DOFS which have been previously proposed are only able to detect dynamic disturbances along the sensing fibre. In this thesis, a new sensing technique has been developed which is capable of quantifying and tracking multiple dynamic perturbations along the sensing fibre, simultaneously.

The sensing mechanism of the proposed technique relies on the phase of the Rayleigh backscattered light. For any given segment along the fibre, the difference in the phase of the backscattered light radiating from the two ends of that segment changes as a function of the external perturbations at that segment. Therefore, dynamic vibration along the sensing fibre can be extracted by comparing the phase of the backscattered light from two different sections of the sensing fibre. By implementing this technique using an imbalanced Mach-Zehnder Interferometer (IMZI), a distributed sensor was developed that was capable of quantifying dynamic perturbations within the frequency range of 200Hz ~5kHz along a 1km sensing fibre.

Furthermore, the same principle was used to develop a distributed magnetic field sensor. By coupling an optical fibre to a magnetostrictive wire and by using this combination as a magnetic field to strain transducer, a distributed magnetic field sensor was formed with magnetic intensity range of 1Gs - 8Gs and frequency range of 50Hz ~5kHz. In addition, the IMZI arrangement was used as a frequency-to-intensity convertor to develop a distributed dynamic strain sensor based on Brillouin scattering. The proposed sensor exhibited a strain range of 400 µ.epsilon 4 m.epsilon and a sensing range of 2km.
Masoudi, Ali
8073fb9b-2e6c-46c9-89cf-cb8670d76dc0
Masoudi, Ali
8073fb9b-2e6c-46c9-89cf-cb8670d76dc0
Newson, Trevor
6735857e-d947-45ec-8163-54ebb25daad7

Masoudi, Ali (2015) Design and application of a distributed optical fibre dynamic strain sensor. University of Southampton, Physical Sciences and Engineering, Doctoral Thesis, 132pp.

Record type: Thesis (Doctoral)

Abstract

Over the past two decades, distributed optical fibre sensors (DOFS) based on Brillouin and Raman scattering have been extensively studied. As a result, a wide range of distributed temperature and strain sensors with different sensing range and accuracy levels have been developed. However, due to the weak nature of Brillouin and Raman scattering, most of the research in this field has been focused on DC or quasi-DC measurement of temperature and strain. On the other hand, the Rayleigh-based DOFS which have been previously proposed are only able to detect dynamic disturbances along the sensing fibre. In this thesis, a new sensing technique has been developed which is capable of quantifying and tracking multiple dynamic perturbations along the sensing fibre, simultaneously.

The sensing mechanism of the proposed technique relies on the phase of the Rayleigh backscattered light. For any given segment along the fibre, the difference in the phase of the backscattered light radiating from the two ends of that segment changes as a function of the external perturbations at that segment. Therefore, dynamic vibration along the sensing fibre can be extracted by comparing the phase of the backscattered light from two different sections of the sensing fibre. By implementing this technique using an imbalanced Mach-Zehnder Interferometer (IMZI), a distributed sensor was developed that was capable of quantifying dynamic perturbations within the frequency range of 200Hz ~5kHz along a 1km sensing fibre.

Furthermore, the same principle was used to develop a distributed magnetic field sensor. By coupling an optical fibre to a magnetostrictive wire and by using this combination as a magnetic field to strain transducer, a distributed magnetic field sensor was formed with magnetic intensity range of 1Gs - 8Gs and frequency range of 50Hz ~5kHz. In addition, the IMZI arrangement was used as a frequency-to-intensity convertor to develop a distributed dynamic strain sensor based on Brillouin scattering. The proposed sensor exhibited a strain range of 400 µ.epsilon 4 m.epsilon and a sensing range of 2km.

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More information

Published date: January 2015
Organisations: University of Southampton, Optoelectronics Research Centre

Identifiers

Local EPrints ID: 375125
URI: https://eprints.soton.ac.uk/id/eprint/375125
PURE UUID: cd78562b-3328-47bf-ab61-6df0b7f65cdb
ORCID for Ali Masoudi: ORCID iD orcid.org/0000-0003-0001-6080

Catalogue record

Date deposited: 22 Jun 2015 10:02
Last modified: 16 Feb 2019 01:32

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