Simultaneous Measurement of Strain and Acoustic Emission Using a Passive Homodyne Demodulated Fiber-Optic Sensor

  • Kexing Liu

Abstract

Simultaneous measurement of strain and acoustic emission is often required in fiber optic structural sensing. This is of particular importance in aircraft structural integrity monitoring where weight saving, minimum perturbation, and safety are essential.1 Over the past few years a number of different sensor configurations (with their respective advantages and disadvantages) have been proposed.2 Most of the techniques require either a narrow linewidth laser that is continuously tunable over a wavelength range of about 20nm without mode-hops or a relatively high power broad-band lightsource that has low intensity noise. This paper proposes a technique that uses the standard fiber Michelson interferometer with a 3x3 directional coupler to obtain quadrature outputs and to process the strain and acoustic emission signals in parallel.

Keywords

Coupler 

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References

  1. 1.
    R.M. Measures and K. Liu, Interferometric fiber optic sensor demodulation for smart structures, IEEE Circuits and Devices, 8:4 (1989).Google Scholar
  2. 2.
    K. Liu and R.M. Measures, Signal demodulation techniques for localised interferometric strain sensors, J. of Intelligent Material Structures and Systems, 15:1255 (1990).Google Scholar
  3. 3.
    K. Liu, S.M. Ferguson, and R.M. Measures, Fiber-optic interferometric sensor for the detection of acoustic emission within composite materials, Optics Letters, 15:1255 (1990).CrossRefGoogle Scholar
  4. 4.
    T. Valis, E. Tapanes, K. Liu, and R.M. Measures, Passive quadrature demodulated localized michelson fiber optic strain sensor embedded in composite materials, J. Lightwave Technology, 9:535 (1991).CrossRefGoogle Scholar
  5. 5.
    S.M. Ferguson, The detection of damage induced acoustic emission in advanced composite materials using optical fiber sensors, Master’s thesis, UTIAS (1990).Google Scholar
  6. 6.
    S.K. Sheem, Optical fiber interferometers with [3x3] directional couplers: analysis, J. Appl. Phys., 52:3865 (1981).CrossRefGoogle Scholar
  7. 7.
    K.P. Koo, A.B. Tventen, and A. Dandridge, Passive stabilisation scheme for interferometers using 3x3 fiber directional couplers, Appl. Phys. Lett., 41:616 (1982).CrossRefGoogle Scholar
  8. 8.
    ASTM, Standard test methods for flexural properties of unreinforced and reinforced plastics and electrical insulating materials (metric), ASTM Designation: D 790M-84, Annual Book of ASTM Standards, 8.01 (1984).Google Scholar

Copyright information

© Springer Science+Business Media New York 1995

Authors and Affiliations

  • Kexing Liu
    • 1
  1. 1.Canadian Marconi CompanyVille Saint-LaurentCanada

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