Patent ID: 6552830
Filing Date: 2003-04-22
Classification: G03H,G06K

Abstract:
In a method of making a document having an authentication element of the type including diffractive structures and non-diffractive structures substantially surrounded by said diffractive structures disposed thereupon, said method including a step of forming said diffractive structures and said non-diffractive structures in a common layer of material and characterized in that:said forming said diffractive structures and said non-diffractive structures includes forming a plurality of micro-graphical features; said forming of said micro-graphical features comprises forming a plurality of non-diffractive micro-graphical features embedded in a surround of diffractive structure; said micro-graphical features are selected from the set of micro-graphical features consisting of alphabetic symbols or characters, numerical symbols or characters, and combinations thereof, said alphabetic symbols or characters and numerical symbols or characters being selected from members of any alphabet or symbol set; and said diffractive structures and said non-diffractive structures are formed substantially simultaneously in said common layer of material.