Nanoscale resolution interrogation scheme for simultaneous static and dynamic fiber Bragg grating strain sensing

Perry, Marcus and Orr, Philip and Niewczas, Pawel and Johnston, Michael (2012) Nanoscale resolution interrogation scheme for simultaneous static and dynamic fiber Bragg grating strain sensing. Journal of Lightwave Technology, 30 (20). 3252 - 3258. ISSN 0733-8724

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    Abstract

    A combined interrogation and signal processing technique which facilitates high-speed simultaneous static and dynamic strain demodulation of multiplexed fiber Bragg grating sensors is described. The scheme integrates passive, interferometric wavelength-demodulation and fast optical switching between wavelength division multiplexer channels with signal extraction via a software lock-in amplifier and fast Fourier transform. Static and dynamic strain measurements with noise floors of 1 nanostrain and 10 nanostrain/sqrt(Hz), between 5 mHz and 2 kHz were obtained. An inverse analysis applied to a cantilever beam set up was used to characterise and verify strain measurements using finite element modeling. By providing distributed measurements of both ultahigh-resolution static and dynamic strain, the proposed scheme will facilitate advanced structural health monitoring.