3DAS: a 3-dimensional-structure authentication system
Rudolf L. van Renesse · 1995
It has been argued that the degree of microstructural order of an optical security feature is an approximate measure of its practical value for document security. Examples of highly ordered structures are diffractive devices like holograms, kinograms and zero order devices as well as interference devices like multilayer thin films and liquid crystals. An entirely different type of security feature is the random device which combines a complete lack of structural order with a high degree of security. This paper surveys the polarity of ordered and random structures.