A security device comprises first zero order diffractive microstructure (1) on a substrate, a second zero order diffractive microstructure (2), and an intermediate light transmissive layer (4) separating the two diffractive microstructures. The spacing (sn,n+1) between the first (1) and second (2) diffractive microstructures is small enough so that optical interferences are produced between the diffractive microstructures. A further light transmissive layer (3) covers the second diffractive microstructure (2).
申请公布号
EP1814743(A1)
申请公布日期
2007.08.08
申请号
EP20050793751
申请日期
2005.09.29
申请人
CSEM CENTRE SUISSE D'ELECTRONIQUE ET DE MICROTECHNIQUE SA