Patent ID: 6965709

Claim:
A fluorescent optical position sensor, comprising: a fluorescent optical waveguide comprising a uniform concentration of fluorescent material along the waveguide's length; means for generating a non-uniform distribution of fluorescent light inside of the waveguide; photodetector means for measuring fluorescent light emitted from the waveguide; wherein said photodetector means comprises a first photodetector disposed for measuring a first intensity of light, S 1 , emitted from a proximal end of the waveguide, and a second photodetector disposed for measuring a second intensity of light, S 2 , emitted from a distal end of the waveguide; and processing means, in operative association with the first and second photodetectors, for calculating the location, X, of a position along the waveguide, based on the ratio, S 1 /S 2 , of the first and second intensities of fluorescent light emitted from the ends of the waveguide, as measured by the first and second photodetectors, respectively; as calculated according to the following formula: X = L 2 - 1 2 ⁢ α ⁢ ln ⁡ ( S 1 / S 2 ) where: L=length of the waveguide; α=0.23 B, and B=Fiber Attenuation Coefficient (in db/meter); wherein said first and second photodetectors are remotely located and are coupled to the ends of the fluorescent waveguide via first and second low-loss optical fibers, respectively; and further wherein an excitation means for exciting a localized region of fluorescence inside of the waveguide at an unknown position, X, comprises the proximal end of a third low-loss optical fiber held in close proximity by a support to said waveguide and oriented to illuminate the waveguide from the side; and wherein the distal end of the third optical fiber is coupled to a remotely-located excitation light source.