Varifocal liquid lenses with integrated actuator, high focusing power and low operating voltage fabricated on 200 mm wafers

Abstract

We developed an innovative type of varifocal liquid lens actuated by electrostatic parallel plates. The 3mm diameter lens is made of a polymer membrane that encapsulates a high permittivity liquid in a cavity on top of a glass wafer. Annular electrodes situated below the membrane and on the glass wafer form the electrostatic parallel plates actuator. Applying a voltage between the electrodes reduces the gap and pushes the liquid towards the center of the lens changing the curvature of the membrane. Compared to previous liquid lenses, significant outline improvement (<6×6×0.7 mm) and supply voltage reduction (<25 V ) is demonstrated. Wave front measurements indicate an optical power change of 8 m−1 at 22V RMS that can be further improved. The lenses were fabricated on 200 mm wafers using standard microelectronics processes that make our solution a promising small outline, low voltage and low cost candidate for auto-focus devices in camera phones.