Simultaneous strain, temperature and vibration measurement using a multiplexed FBG/FFPI sensor system

A novel technique for simultaneous measurement of static-strain, temperature and vibration for structural health monitoring is demonstrated using a wavelength-multiplexed in-fibre-Bragg-grating (FBG)/fibre-Fabry-Perot-interferometer (FFPI) sensor system, which combines the advantages of both FBGs and fibre-optic low-coherence interferometry. An experimental system, including two Im long FFPIs with central wavelengths of 1531nm and 1534nm and a FBG with a central wavelength of 1555nm, is demonstrated. A static strain resolution of better than 1 mu epsilon, over a range of 5m epsilon, a temperature sensitivity of 0.1 degrees C and a vibration amplitude sensitivity of better than 1nm/root Hz have been obtained. The system cross-talk measured is less than -50dB.