Patent ID: 6069565
Filing Date: 2000-05-30
Classification: B64D,B64F,G08B

Abstract:
Apparatus for detecting, on a surface which specularly reflects light, the presence of a polarization altering substance on said surface comprising:means for transmitting a pulse of light over a transmitting path to said surface;means for receiving transmitted light;a receiving path for said transmitted light from said surface and from said substance to said means for receiving;means for splitting said transmitted light into a non-isolated portion and an isolated portion;means for delaying one of said non-isolated portion and said isolated portion relative to another thereof to produce a first-to-arrive signal and a second-to-arrive signal;said first-to-arrive signal being completed at an output of said means for delaying before said second-to-arrive signal arrives at said output;means for measuring a first intensity of said first-to-arrive signal and outputting a first signal;means for measuring a second intensity of light of said second-to-arrive signal and outputting a second signal;means for storing reference data, said reference data including first and second measurements, said first and second measurements corresponding to said first and second intensities respectively measured at an initial time;means for storing current data, said current data including third and fourth measurements, said third and fourth measurements corresponding to said first and second intensities respectively measured at a subsequent time; andmeans for comparing said current data to said reference data to detect the presence of said substance on said surface at said subsequent time.