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Method and apparatus for making absolute range measurements

United States Patent

September 24, 2002
View the Complete Patent at the US Patent & Trademark Office
Oak Ridge National Laboratory - Visit the Partnerships Directorate Website
This invention relates to a method and apparatus for making absolute distance or ranging measurements using Fresnel diffraction. The invention employs a source of electromagnetic radiation having a known wavelength or wavelength distribution, which sends a beam of electromagnetic radiation through a screen at least partially opaque at the wavelength. The screen has an aperture sized so as to produce a Fresnel diffraction pattern. A portion of the beam travels through the aperture to a detector spaced some distance from the screen. The detector detects the central intensity of the beam as well as a set of intensities displaced from a center of the aperture. The distance from the source to the target can then be calculated based upon the known wavelength, aperture radius, and beam intensity.
Earl; Dennis D. (Knoxville, TN), Allison; Stephen W. (Knoxville, TN), Cates; Michael R. (Oak Ridge, TN), Sanders; Alvin J. (Knoxville, TN)
UT Battelle, LLC (Oak Ridge, TN), The University of Tennessee Research Corporation (Knoxville, TN)
09/ 705,847
November 3, 2000
This invention was made with support by the United States Government under contract DE-AC05-00OR22725 awarded by the U.S. Department of Energy to UT-Battelle, LLC and the Government has certain rights in this invention.