An improved fibre optic strain sensor for gas tank monitoring with rf subcarrier phase and I&Q demodulation techniques

Graham Thursby, Fengzheng Dong, Brian Culshaw, Guido Massaro, Branko Glisic, Daniele Inaudi

Research output: Contribution to journalConference articlepeer-review

1 Scopus citations


With increased interest in the use of compressed gas as a vehicle fuel, attention has been focussed on the safety issues surrounding the tanks used to store the fuel. Currently it is necessary to remove the tanks from the vehicle in order to inspect them, which entails a considerable cost in manpower and takes the vehicle being out of service. We have been developing a sensor scheme that can provide in situ monitoring of the tanks condition. This entails bonding optical fibre sensors to the tank and using them to measure the strains experienced by the tank during pressurisation. If the tank is significantly damaged, then the tank will expand in a distorted manner. We therefore measure the strain characteristics of a healthy tank and use them as a reference for future measurements. The method of strain measurement is the well established rf subcarrier phase detection technique, however in this application the changes in optical power caused by microbending of the fibres during pressurisation produces inaccuracies. In order to overcome this problem we use both in- phase and quadrature mixing and then take the ratio of the outputs to obtain a value of arctangent that is independent of amplitude.

Original languageEnglish (US)
Article number47
Pages (from-to)381-389
Number of pages9
JournalProceedings of SPIE - The International Society for Optical Engineering
StatePublished - 2005
Externally publishedYes
EventSmart Structures and Materials 2005 - Smart Sensor Technology and Measurement Systems - San Diego, CA, United States
Duration: Mar 7 2005Mar 9 2005

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Computer Science Applications
  • Applied Mathematics
  • Electrical and Electronic Engineering


  • Damage detection
  • Optical fibre sensors
  • rf subcarrier phase detection


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