METHOD AND DEVICE FOR DETERMINING ELONGATION AND STRAIN SENSOR USED FOR SAME

摘要

The invention relates to fibre-optic strain sensors which are intended to be embedded in materials or mounted to the surface of same in order to monitor deformations therein and to a method of taking readings from said sensors. The invention consists of a quasi-distributed-type sensor comprising one or more fibre optics (2) and having a long or short base, which can be used to measure the complete axial deformation along the length of the sensitive part and between specific pre-defined points. The fibre optics comprise: at least one Fabry-Perot cavity which is formed by reflectors (R<SUB>1</SUB>...R<SUB>I</SUB>) that are continuously sensitive to deformation and temperature, and at least one temperature-sensitive Bragg grating (B<SUB>1</SUB>...B<SUB>J</SUB>). The fibre or the fibre assembly is embedded in a sheath of material (3) having a composition and geometry that enable the optimal, continuous transmission of the deformation of the host material (1) to the measuring element. The read device (4) uses low-coherence interferometry in order to measure the length of the cavities and the frequency variation of the Bragg gratings.