Fiberoptic interferometric sensor.

摘要

An optical fiber interferometric system includes a pair of single-mode, polarization-preserving fibers having distal and proximal ends. The cladding of a selected portion of one of the fibers having been removed to allow an evanescent portion of a light wave traveling within the fiber to interact with any medium surrounding the selected portion of the fiber. A light source for producing a light of known character is coupled to the proximal ends of the pair of optical fibers for introducing a source signal to the pair of fibers. A reflector at the distal ends of the optical fibers reflects the light from the distal ends back toward the light source. The return signals are used to construct an interferogram which is observed to detect any modulation in the the phase of the light signals. The modulation is examined ratiometrically to derive a change in the index of refraction of the medium sunounding the selected portion substantially free of any environmentally induced phase noise.