Integrated Optofluidic Iris

An optofluidic iris, which uses the absorption of an opaque liquid in combination with a second transparent liquid for defining optical apertures of variable diameters, tuned by directly deforming a ring-shaped liquid-liquid interface using electrowetting on dielectrics, is presented. The novelty lies not only in the absence of any moving parts or membranes but also in the design of the liquid ring, which allows planar microfabrication processes to be used exclusively for defining all functional parts of the iris. When compared to other optofluidic approaches, this concept combines ultracompactness, full integration, moderate drive voltage (75 V), low power consumption (<; 5 mW), highly robust and repeatable tunability, adequate tuning speed (<; 1 s), high uniform transmission (>; 86%), and an optical quality suitable for imaging applications, with a fabrication process which will allow mass fabrication.