Patent ID: 7871741
Filing Date: 2011-01-18
Classification: B41M,B42D,G03H,Y10S

Abstract:
1. A method of producing a security document or article including a substrate transparent to at least visible light and a transmissive diffractive optical microstructure, including the steps of: applying an opacifying layer to at least one surface of the transparent substrate; exposing an area of the opacifying layer to laser radiation to ablate apertures in selected portions of the opacifying layer and thereby to form a transmissive diffractive optical microstructure on said surface of the substrate, wherein the transmissive diffractive optical microstructure is formed such that visible light emitted from a source on one side of the opacifying layer will pass through the apertures and create a diffraction pattern which generates an image in a plane located on the side of the opacifying layer opposed to the light source.