Microlenses fabricated by melting a photoresist on a base layer

We report on the fabrication of novel refractive microlens arrays in photoresists, in particular on lenses with numerical apertures ranging from 0.1 to 0.3. A base layer technique is described that makes it possible to fabricate lower numerical aperture lenses in resist, compared with microlenses on glass substrates. The wave aberrations were measured in a Mach-Zehnder interferometer. Diffraction-limited performance was achieved for a numerical aperture of 0.2 and a lens diameter of 270 μm.