Large-area origination and replication of microstructures with optical functions

Structuring surfaces on a microscopic scale allows to modify their optical properties. The exact tailoring of these properties requires very precise manufacturing techniques. On large areas, mainly replication techniques allow competitive production cost. This paper addresses the challenge of originating and replicating microstructures with optical functions with dimensions between 200nm and 50m on areas of up to half a square meter. The whole experimental process chain is described and discussed. For the microstructure origination, interference lithography was used. An argon ion laser was chosen as a coherent light source at a wavelength of 364nm. Periodic and stochastic interference patterns were recorded in positive photoresist by using large interferometer set-ups. Structures with good homogeneity were originated on areas of up to 4800 cm2 by optimizing the set-up and the photoresist processing. By carefully modeling resulting resist profiles it was possible to orig inate a wide variety of surface-relief profiles including prismatic ones. Different replication techniques like hot compression molding and UV casting are discussed. Some applications of large-area micro-structured films and sheets are presented.