The injection molding of a microfeatured component, a diffractive optical element, was studied. The component has a wave-like pattern on the surface, with amplitude 0.5 μm and wavelength 3 μm. Two different polymers were used: a polymethylmethacrylate and an ethylene-norbornene copolymer (cyclic olefin copolymer). The topography was investigated using white light interferometry (WLI), atomic force microscopy (AFM), and scanning electron microscopy (SEM). A new WLI-based technique is proposed for rapid quantification of the replication of periodic surface patterns. This technique gives almost the same information regarding the degree of replication as AFM but can be performed much faster. Quantitative data on the degree of replication as function of processing conditions are presented. At optimal conditions, almost perfect replication is obtained using both materials. At suboptimal conditions, it is observed that the degree of replication increases with increasing injection velocity and increasing mold temperature, with similar characteristics for both materials. The difference in replication quality between the two materials seems to be related to the different temperature dependencies of the viscosities.
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