Security document including a nanoparticle-based authentication device

摘要

A security document (1) comprising a sheet like substrate (2) having one or more layers containing particles for forming an authentication device (10) in a first location on the security document (1), the particles having at least a first dimension in the range 1 to 200 nanometers. Various methods of producing a security document and a method of producing a security feature are also disclosed.