DISTRIBUTED FIBER OPTIC SENSOR USING CLAD MATERIAL LIGHT BACKSCATTERING

摘要

A distributed fiber-optic sensor is obtained by using cladding that produces a change in the intensity of scattered light in the cladding of an optical fiber in response to a change in the environment of the cladding. The change in clad scattered light is coupled into the core causing a change in the intensity of backscattered light in the core. A sensing means such as an optical time domain refractometer is used to determine the change in intensity of the core backscattered light at a specific location along the fiber. The change in intensity of the scattered light in the clad is caused by overall changes in the amount of light in the cladding and changes in the number, size or both of the refractive index inhomogeneities in the cladding. These inhomogeneities can be, but are not limited to, composition variations, density variations of the same composition, phase separations, voids, or particulate inclusions.