Real-time distortion measurement in a slab structure using hetero-core fiber optic embedded sensors

A shape sensor technique has been developed for the real-time measurement of distortion sensitive plane slab structures using a hetero-core splice fiber optic sensor. It has been found that the optical loss of hetero-core fiber sensing element monotonically increased with bending action of hetero-core portion. This sensor was applied to measure distortion in plane shape. In addition to the unique sensing capability of hetero-core sensors, we employed an LD/PD system in order to realize a cost effective real-time measurements which enabled us to carry out an accurate detection with a small standard deviation in the temporal stability of 0.004V. The developed plane shape sensor consisted of 3 hetero-core sensor elements properly arranged with 45-degree crossing angles, with producing a displacement resolution of 0.5mm for 20mm dynamic range.