Optical fiber sensor and method

Abstract

An optical fiber sensor for detecting curvature of a body / structure comprises a cladding having an outer periphery. A central core receives and transmits light. The central core has Bragg gratings and is positioned in neutral planes of the cladding. Peripheral cores receive and transmit light. The peripheral cores have Bragg gratings and are peripherally positioned in the cladding with respect to the neutral planes. A connection configuration is provided in the outer periphery of the cladding to attach the optical fiber sensor to a body / structure such that the central core and the peripheral cores are in a predetermined orientation with respect to the body / structure to measure curvature of the body / structure.

Description

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to optical fibers and, more particularly, to optical fiber sensors to measure deformation.

[0003] 2. Background Art

[0004] Optical fiber systems offering sensing functions have been used in numerous applications. One known sensor technology for optical fibers is the Bragg grating sensor. The Bragg grating is a periodic variation of the refractive index along the fiber axis and it is photoimprinted in the core of the fiber by using UV light. The main property of a Bragg grating is that part of the light going along the fiber is reflected back by the grating. This process is wavelength selective and the wavelength with the highest reflectivity is called the Bragg wavelength (typically located at the center of the spectral response). Any temperature variation or strain applied to the optical fiber might result in a Bragg wavelength shift and / or spectral deformation, depending on how perturbations ...

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