Liquid crystal lens with large focal length tunability and low operating voltage.

We demonstrate a tunable focus liquid crystal (LC) lens by sandwiching a homogeneous LC layer between a planar electrode and a curved electrode. The curved electrode which is made of conductive polymer has parabolic shape with a large apex distance. Such design dramatically reduces the phase loss which leads to a short focal length (~15 cm). By using a thin top glass substrate on the curved electrode side, the operating voltage of the lens cell is reduced to ~23 V(rms). This LC lens has advantages in wide focal length tunability, low operating voltage, and good mechanical stability.