title: Tunable microfluidic microlenses.
abstract: A novel type of liquid microlens, bounded by a microfabricated, distensible membrane and activated by a microfluidic liquid-handling system, is presented. By use of an elastomer membrane fabricated by spin coating onto a dry-etched silicon substrate, the liquid-filled cavity acts as a lens whereby applied pressure changes the membrane distension and thus the focal length. Both plano-convex and plano-concave lenses, individual elements as well as arrays, were fabricated and tested. The lens surface roughness was seen to be approximately 9 nm rms, and the focal length could be tuned from 1 to 18 mm. This lens represents a robust, self-contained tunable optical structure suitable for use in, for example, a medical environment.
authors.affiliation: Laboratory for Micro-optics, Institute of Microsystem Technology, University of Freiburg, Georges-Köhler-Allee 102, 79110 Freiburg, Germany. werber@imtek.de
authors.forename: Armin
authors.initials: A
authors.lastname: Werber
authors.forename: Hans
authors.initials: H
authors.lastname: Zappe