Fabrication of three-dimensional microlens arrays in sol–gel glass

We present a novel technological approach for the realization of three-dimensional microlens arrays in sol-gel glass. Hundred micron thick cylindrical SU-8 structures are used to generate a polydimethylsiloxane (PDMS) mold that is subsequently filled with AZ 4562 photoresist. During a thermal softening process, the upper part of the photoresist cylinder transforms into a spherical-like shape. An in-house developed sol-gel material with low shrinkage is then used to replicate via a second PDMS mold the photoresist lenses into crack-free glass structures with optical quality.