Patent ID: 6521884
Filing Date: 2003-02-18
Classification: G01B,G01D

Abstract:
Device for measuring the distance separating two members which can be displaced one with respect to the other comprising a permanent magnet fixed on a first surface of one of the members and a first electro-optical device fixed on a second surface of the other member, the first electro-optical device comprising:a beam source configured to emit an optical beam along a first path extending along the second surface and leading to an optical assembly, a Faraday-effect magneto-optical film disposed with optical components configured to act as a polarizer and an analyser along a second path inside the optical assembly, the Faraday-effect magneto-optical film also being disposed in a magnetic field of the permanent magnet when the first and second surfaces of the two members are in proximity to one another, the optical beam entering the optical assembly and traveling along the second path to interact with the Faraday-effect magneto-optical film and the optical components and then exiting from the optical assembly, and a photodetector disposed to receive the optical beam exiting from the optical assembly and configured to transform the optical beam luminous intensity into an electric signal whose amplitude depends on the distance separating the first and second surfaces of the two members when they are proximate to one another.