Patent ID: 7183765

Claim:
A micro-position sensing system comprising: light source means for producing polarized light; an optical fiber connected to said light source means and extending to a sensing end; a magneto-optic material coupled to the sensing end of the optical fiber and capable of rotating the plane of polarization of polarized light passing therethrough when subject to a magnetic field, the magneto-optic material having a reflective surface configured to back-reflect incident polarized light back through the magneto-optic material and the optical fiber; a permanent magnet positioned adjacent the magneto-optic material for providing a magnetic field thereto, said magnet being independently movable relative to the magneto-optic material in a radial direction to the longitudinal axis of the optical fiber at the sensing end so as to rotate the plane of polarization of polarized light passing through the magneto-optic material as a function of the relative position of the magnet, and said magnet having a range of motion which keeps the magneto-optic material within the range of the magnetic field to maintain continuity of response; and means for determining the position of the magnet relative to the sensing end of the optical fiber by determining the change in Faraday rotation of the plane of polarization of the back reflected polarized light from a calibrated reference position.