STRAIN SENSOR WITH OPTICAL FIBRE BRAGG GRATINGS

摘要

Strain sensors, and in particular strain rosettes, are described and claimed, in which the strain sensing elements are fibre Bragg gratings. Strain sensors in accordance with the described invention comprise first and second fibre Bragg gratings, and a length of optical fibre connecting the gratings in series, each grating being substantially straight and the two gratings being non-parallel and having different nominal Bragg wavelengths, the connecting length of optical fibre having a bend, characterised in that a portion of the connecting length is tapered, the tapered portion including an elongate waist portion having a reduced cross sectional area and said bend is formed in the waist portion.