Security paper comprises a window covered by a transparent or translucent feature layer with motif zones comprising achromatic microstructures with angle-dependent transmission and reflection properties

摘要

Security paper comprises a window covered by a transparent or translucent feature layer with motif zones that are in the form of symbols, patterns or codes and comprise achromatic microstructures with angle-dependent transmission and reflection properties giving a different appearance when viewed from opposite sides of the feature layer. An independent claim is also included for checking the authenticity of a transparent or translucent security element by selecting a test object giving expected images of different appearance when viewed from opposite sides (of an authentic security element), observing the test object through opposite sides of the security element and comparing both images with the expected images.