US Patent 7019890 Hybrid electro-active lens

An electro-active lens is disclosed. The lens includes at least one electro-active cell to provide a lens having at least two focal lengths, the electro-active cell capable of adjusting its focal length based on voltages applied to the electro-active cell. The voltage is supplied by an alternating current source, including a flying capacitor circuit. The electro-active lenses reduce birefringence through the use of a single cholesteric liquid crystal electro-active cell.