Zero-order diffractive filter

摘要

The present invention relates to Zero-order Diffractive filters (ZOFs), comprising a first layer having periodic diffractive microstructures and a second layer, wherein said first layer has a refractive index higher than said second layer by at least 0.2, and nanoparticles located in at least one of said layers which affect the refractive index of said at least one of said layers. The present invention further relates to methods of manufacturing such ZOFs, to the use such ZOFs e.g. in security devices and to the use of specific materials for manufacturing ZOFs.