Replication techniques for micro-optics

Materials and techniques for manufacturing replicated micro-optical elements are reviewed Factors such as choice of material, changes in physical dimensions, feature size and cost are considered. The manufacture of a 1.5 mu m period radial grating for a rotation encoder is described. Replicas of the grating were made from the same Ni shim by reel-to-reel UV embossing, CD injection moulding and flat bed hot embossing. The dimensions of the replica parts were measured and compared. The diffraction efficiency of the UV embossed replicas was found to be only slightly less than the theoretical maximum efficiency.