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.
A novel design for thermo-pneumatically actuated, membrane-based micro-mirror devices, using an elastomer membrane fabricated in a spin-coating process on a dry-etched silicon substrate, is presented. The silicon mirror devices are etched from the substrate and fixed to the highly elastic 50 µm thick membrane and actuated by thermo-pneumatic pressure. This pressure is generated by a micro-hotplate bonded to the backside of the silicon substrate. Such devices provide strokes from 0 to 80 µm and tilting angles in the range from 0° to 13°, relative to the substrate surface. Thermo-pneumatic actuation achieves large angle and stroke deflection, making this approach suitable for a large array of applications. Tilting mirrors, piston mirrors as well as mirror arrays have been realized using this technology.
An overview of recent activities in the area of tunable micro-optical components is given. These include polymer-based deformable mirrors for adaptive optics, tunable microlenses and arrays using fluids and membranes, pneumatically actuated scanning micromirrors and tunable Bragg filters and mirrors using swelling polymers. For each device, the structure, essential fabrication technology and optical characteristics, as well as a discussion of application areas are presented.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.