Patent ID: 8439402
Filing Date: 2013-05-14
Classification: B42D,G07D

Abstract:
1. A security document and/or a document of value, comprising a sheet material including an optical structure comprising: first and second opposite outside faces; at least a first interface comprising a first screen of microreliefs and arranged in such a manner that travel through said first interface from the first outside face towards the second outside face, passes from a first medium having a first refractive index to a second medium having a second refractive index that is greater than the first; and at least one second interface comprising a second screen of microreliefs and arranged in such a manner that travel through said second interface from the first outside face towards the second outside face, passes from a third medium having a third refractive index to a fourth medium having a fourth refractive index less than the third; wherein said first and second interfaces are completely offset one relative to the other when the structure is observed in a direction substantially perpendicular to at least one of the outside faces, wherein at least one of the first screen of microreliefs and the second screen of microreliefs overlap exactly a substantially smooth zone of one of the outside faces; and wherein light is able to travel between the at least one first interface and the at least one second interface.