Patent ID: 8883273
Filing Date: 2014-11-11
Classification: B41M,B42D,B82Y,G02B,Y10T

Abstract:
1. An optically variable security device comprising a photonic crystal, wherein the photonic crystal is provided as a self-supporting film or the photonic crystal is supported by a substrate or carrier layer, wherein the photonic crystal is configured to receive incident light and to selectively reflect or transmit the incident light to generate a first optically variable effect observable over a first set of directions and to selectively reflect or transmit the incident light to generate an optical effect observable over a second set of directions that is different from the first set of directions, wherein the first and second sets of directions lie in substantially different planes which intersect to define the normal to a crystal surface, and wherein the first optically variable effect observable over the first set of directions is different from the optical effect observable over the second set of directions.