A new approach to polymeric microlens array fabrication using soft replica molding

This letter reports a new fabrication method of polymeric, nonspherical microlens arrays based on the soft replica molding process, employing elastomeric molds with desired microlens patterns. The elastomeric molds are made of polydimethylsiloxane (PDMS) and prepared through an innovative process consisting of excimer laser microdrilling, spin coating, and soft replica molding. The demonstrated microlens arrays, made of polymethylmethacrylate, include three footprints with diameters of 50, 100, and 150 mum. Results show the microlens arrays have both good surface uniformity and high-quality optical properties. The resulting microlenses have focal lengths varying from tens to hundreds of micrometers and present low f-number ranging between 0.8 and 1.5. The facts that the PDMS elastomeric molds are chemically inert and that all processing steps are executed in ambient environment and at low temperature render the proposed approach a potential method for mass production of microlens arrays.