Preliminary investigation of surface finish of a contact lens polymer in ultra-high precision diamond turning

Abstract

Contact lens manufacture requires high deal of accuracy and surface integrity. Amidst numerous optical manufacturing techniques, single-point diamond turning is widely employed in the making of contact lenses due to its capability of producing optical surfaces of complex shapes and nanometric accuracy. This manufacturing technique is however affected by chemical and/or tribo-electric wear, which are known dominant wear mechanisms found in precision turning of polymeric materials. Therefore an adequate analysis of this manufacturing process and a cross-examination of factors affecting surface finish could aid in ensuring lens optical quality. This research work is aimed at examining the surface finishes resulting from applying various combinations of cutting parameters during ultra-high precision machining of contact lenses.