Method and apparatus for making absolute range measurements

Patent · Fri Jan 01 04:00:00 EST 1999

OSTI ID:872349

Allison, Stephen W ^[1]; Cates, Michael R ^[2]; Key, William S ^[1]; Sanders, Alvin J ^[1]; Earl, Dennis D ^[1]

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1. Knoxville, TN
2. Oak Ridge, TN

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 an object which causes it to be split (hereinafter referred to as a "beamsplitter"), and then to a target. The beam is reflected from the target onto a screen containing an aperture spaced a known distance from the beamsplitter. The aperture is sized so as to produce a Fresnel diffraction pattern. A portion of the beam travels through the aperture to a detector, spaced a known distance from the screen. The detector detects the central intensity of the beam. The distance from the object which causes the beam to be split to the target can then be calculated based upon the known wavelength, aperture radius, beam intensity, and distance from the detector to the screen. Several apparatus embodiments are disclosed for practicing the method embodiments of the present invention.

• Research Organization: LOCKHEED MARTIN ENERGY RES COR
• DOE Contract Number: AC05-96OR22464
• Assignee: University of Tennesee Research Corporation (Knoxville, TN); Lockheed Martin Energy Research Corporation (Oak Ridge, TN)
• Patent Number(s): US 5914785
• OSTI ID: 872349
• Country of Publication: United States
• Language: English

Related Subjects

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electromagnetic radiation
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hereinafter
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produce
radiation
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screen
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wavelength