A MEMS-based variable micro-lens system

We present a tunable liquid micro-lens system exhibiting a tuning range of back focal length between 2.3 mm and infinity achieved by applying a voltage of 0-45 V. The lens actuation mechanism is based on electro-wetting on dielectrics (EWOD) and the system is fabricated in MEMS technology. In this system, two density-matched optical fluids are located in a centring structure which was defined by an anisotropic etching process. The system design provides an initial back focal length of a few millimetres and is robust against shocks and vibrations.