ABSTRACT

There exist a great variety of fiber optic sensors (FOSs) for structural monitoring in both the academic and industrial areas. The greatest advantages of FOS are intrinsically linked to the optical fiber itself that is either used as a link between the sensor and the signal conditioner, or becomes the sensor itself in the case of long-gauge and distributed sensors. The measurement setup uses low-coherence interferometry to measure the length difference between two optical fibers installed on the structure to be monitored. Bragg gratings are periodic alterations in the index of refraction of the fiber core that can be produced by adequately exposing the fiber to intense ultraviolet (UV) light. The produced gratings typically have length of the order of 10 mm. Raman scattering is the result of a nonlinear interaction between the light traveling in a fiber and silica. Brillouin scattering sensors show an interesting potential for distributed strain and temperature monitoring.