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RETROREFLECTIVE SURFACE

  • US 3,712,706 A
  • Filed: 01/04/1971
  • Issued: 01/23/1973
  • Est. Priority Date: 01/04/1971
  • Status: Expired due to Term
First Claim
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1. A retroreflector constructed so that diffraction is a dominant factor governing the angular divergence of retroreflected light from perfect retroreflection, said retroreflector consisting essentially of a hexagonal close packed array of contiguous cube corners having windows which are equilateral triangles defined at the intersecting boundaries of respective contiguous cube corners in said array by three sets of continuous parallel lines all oriented in a plane with included angles of 60* between respective lines of each such set at a common point of intersection, said cube corners each having three adjacent faces intersecting at dihedral angles of 90* + OR 2.8 minutes of arc, the respective adjacent lines in each such three sets of parallel boundary lines being all equally spaced apart with normal spacing in the range from 15.5 to 830 microns between adjacent lines of each set, said normal spacing of parallel lines being a value within the defined range selected to produce a desired angular divergence of the retroreflected light due to diffraction, and the faces of said cube corners all being essentially specular mirror surfaces having reflective coefficients of at least 0.6.

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