Diamond turning of micro-lens array on the roller featuring high aspect ratio

Abstract

Slow slide servo (S3)-assisted diamond turning combining roll-to-roll replication has been extensively regarded as a very promising technique for the generation of micro-lens arrays (MLAs) for optical applications. However, to avoid undesired interference between the flank surface of the tool and the machined structure, the aspect ratio (AR) (ratio of height to aperture) of machined MLAs is usually restricted to be very small as for the diamond-turning process. To generate MLAs with high AR on the roller, a new method is proposed to increase the practical clearance angle during turning by lowering the position of the cutting tool tip in vertical direction. The optimal tool path determination algorithm is developed with full consideration of tool radius as well as tool position. Effectiveness of the proposed method is demonstrated well experimentally through turning a MLA with AR of 0.158 (79-μm height to 500-μm aperture).