Dry etching for coherent refractive microlens arrays

Coherent arrays of refractive micro-optics are fabricated in the surface of silicon using a combination of lithographic and reactive-ion etching (RIE) techniques. The aspheric profile can be approximated in a stepwise manner by iterative steps of photolithography and RIE (binary optics technology), by direct etching of a preshaped polymer microlens etch mask into the substrate, or by analog etching of a lens profile directly into the substrate through a pinhole mask.