Optimization and theoretical modeling of polymer microlens arrays fabricated with the hydrophobic effect

High-performance polymer microlens arrays were fabricated by means of withd rawing substrates of patterned wettability from a monomer solution. The f-n umber (f(#)) of formed microlenses was controlled by adjustment of monomer viscosity and surface tension, substrate dipping angle and withdrawal speed , the array fill. factor, and the number of dip coats used. An optimum with drawal speed was identified at which f(#) was minimized and array uniformit y was maximized. At this optimum, arrays of f/3.48 microlenses were fabrica ted with one dip coat with uniformity of better than Deltaf/f similar to +/ -3.8%. Multiple dip coats allowed for production of f/1.38 lens arrays and uniformity of better than Deltaf/f similar to +/-5.9%. Average f(#)s were r eproducible to within 3.5%. A model was developed to describe the fluid-tra nsfer process by which monomer solution assembles on the hydrophilic domain s. The model agrees well with experimental trends. (C) 2001 Optical Society of America.