Abstract: Device for measuring corrosion in a structure. It comprises: at least one assembly comprising a metallic part (2) intended to be fixed to the structure and able to deform under the effect of corrosion and/or a thermomechanical variation, and transduction means (4) comprising an optical fibre (3) fixed to the metallic part in a prestressed state, the transduction means being able to modify light propagating in the fibre under the effect of a stress applied to the fibre; means for measuring and processing the spectral responses supplied by the transduction means of said at least one assembly. The metallic part is segmented longitudinally in order to form an alternation of segments covered by a corrosion-protection material (8) and uncovered segments, in order to distinguish the thermomechanical influence of the structure from the mechanical effects caused by corrosion.

Abstract: Device for measuring corrosion in a structure. It comprises: at least one assembly comprising a metallic part (2) intended to be fixed to the structure and able to deform under the effect of corrosion and/or a thermomechanical variation, and transduction means (4) comprising an optical fibre (3) fixed to the metallic part in a prestressed state, the transduction means being able to modify light propagating in the fibre under the effect of a stress applied to the fibre; means for measuring and processing the spectral responses supplied by the transduction means of said at least one assembly. The metallic part is segmented longitudinally in order to form an alternation of segments covered by a corrosion-protection material (8) and uncovered segments, in order to distinguish the thermomechanical influence of the structure from the mechanical effects caused by corrosion.

Abstract: Extensometer with flexible test specimen and Bragg gratings applied in particular to the monitoring of concrete structures, is configured to measure deformations of a host material and comprises at least one test specimen which undergoes linear bending stresses, and at least one Bragg grating formed in an optic fibre and fixed to the test specimen. The extensometer configured such that any deformation of the host material is transmitted to the grating via the test specimen. The extensometer also comprises mechanical means which transform deformation of the material into bending of the test specimen, which deforms the grating.

Abstract: This extensometer, applied in particular to the monitoring of concrete structures, is intended to measure deformations of a host material and comprises at least one test specimen (18) which undergoes linear bending stresses, and at least one Bragg grating (14) formed in an optic fibre (16) and fixed to the test specimen. Any deformation of the host material is transmitted to the grating via the test specimen. The extensometer also comprises mechanical means (20, 22) which transform deformation of the material into bending of the test specimen, which deforms the grating.

Abstract: An extensometer including a base, a tensioned optical fiber, and a Bragg grating. The extensometer relates particularly to monitoring of structures. Part of the optical fiber containing the Bragg grating is arranged in a tube. This part is tensioned between the two ends of the tube. The ends of this part are fixed to the ends of the tube, and the tube is rigidly fixed to a host material.

Abstract: According to the invention, that relates particularly to monitoring of structures, part of the optical fiber (4) containing a Bragg grating (R) is arranged in a tube (16); this part is tensioned between the two ends of the tube; the ends of this part are fixed to the ends of the tube; this tube will be rigidly fixed to a host material (2).

Abstract: A Bragg grating inclinometer that includes an upper part, a lower part forming a pendulum suspended from the upper part by an articulation, at least two portions of optic fiber placed on either side of the articulation, the ends of each portion being fastened to the two parts, each portion being previously put under tension between the two parts, and at least one Bragg grating in one of the portions. Any variation in the inclination of a structure to which the upper part is fastened induces a stress on the grating, which then modifies a light propagating in the portion where it is placed. The variation in inclination is determined from the modified light. The inclinometer can be applied in particular to the surveillance of civil engineering structures.

Abstract: This inclinometer comprises an upper part (4), a lower part (6) forming a pendulum suspended from the upper part by an articulation (8), at least two portions of optic fibre (20, 22) placed on either side of said articulation, the ends of each portion being fastened to the two parts, each portion being previously put under tension between said parts, and at least one Bragg grating (24) in one of the portions. Any variation in the inclination of a structure to which is fastened the upper part induces a stress on the grating, which then modifies a light propagating in the portion where it is placed. The variation in inclination is determined from the modified light. The invention applies in particular to the surveillance of civil engineering structures.

Abstract: The present invention relates to a planar, rosette-type, optical microsystem with strain gauges having dielectric guides used for measuring a system of strains or stresses applied to a part, in which the part is under purely longitudinal strain, at least one rosette being formed by at least two strain gauges with dielectric guides (J1, J2, J3) and in which a calculating circuit makes it possible to determine said strain by resolving a system of equations.