An electrically tunable liquid crystal lens with coaxial bi-focus and single focus switching modes

A hole-patterned electrode liquid crystal (LC) lens with electrically switching coaxial bi-focus and single focus modes of tuning is demonstrated. The proposed LC lens mainly consists of a two LC layer (TLCL) structure with different thicknesses to achieve higher focusing power than the conventional hole-patterned electrode LC lens with the same aperture size. In the TLCL structure, one LC layer, doped with 3 wt % RM257, was photopolymerized to achieve a fixed focusing power of 18.5 Diopter. Due to polarization dependence in TLCL lenses, an additional 90° twisted nematic (TN) cell was used to change the incident polarization in order to switch lens functions on or off. As a result, a fixed focusing power of 18.5 Diopter was achieved when voltages of 10 Vrms were applied to the 90° TN cell. In addition, the switching capabilities of the bi-focus and single focus modes were achieved when operating individually with applied voltages from 20 Vrms to 90 Vrms, and higher voltages of over 90 Vrms, respectively. The maximum focusing power in the fabricated TLCL lens is 30.9 Diopter.