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: 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: 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.