An apparatus includes a planar substrate and an array of substantially transparent spherical micro-lenses forming a pattern. The pattern has an internal two-dimensional lattice symmetry on the planar substrate. Each micro-lens includes a convex bulge or a concave depression in a surface of the planar...http://www.google.com/patents/US7297474?utm_source=gb-gplus-sharePatent US7297474 - Tunable micro-lens arrays
