High-sensitivity fibre-optic strain sensors for measuring structural distortion

Abstract
A high sensitivity fibre-optic microbend strain sensor for detecting bending of large mechanical structures has been constructed; experimental data on transmission modulation against structural strain are presented. Optical time domain reflectometry for detecting strains at several structural points simultaneously by placing many sensors in tandem along a single fibre is described. Structural bend radii of greater than 5 km have been measured.