Replication technology for Diffractive Optical Elements

Replication technologies such as embossing, moulding and casting in polymer materials are highly attractive for the fabrication of surface-relief Diffractive Optical Elements (DOEs) and are expected to become key technologies for their production in the future. They have very high resolution, typically in the nanometer range, and allow the fabrication of large area, complex microstructure by low-cost, high volume industrial production processes. This paper gives a summary the current main replication technologies for surface microstructure and discusses their extension to a wider range of DOE microstructures, involving developments such as the replication of deeper and higher aspect ration microstructure and the maintenance of an optically precise form for critical surfaces such as imaging DOEs. Examples and recent results for DOE fabrication by replication technology are presented. New possibilities resulting from the combination of replication technology with other processes such as dry etching and thin film coating are discussed.