High-efficiency switchable diffractive lens

We demonstrate that, by using circular array of electrode pattern and applying multi-level phase modulation in each zone, a high-efficiency switchable electro-optic diffractive lens using liquid crystal as the active medium can be produced as a switchable eyewear. The lens is flat and the thickness of the liquid crystal is 5 μm. Two different designs are presented. In one design, all the patterned electrodes are distributed in one layer with a 1-μm gap between the electrodes. In the other design, the odd- and even-numbered electrodes are separately patterned in two layers without any lateral gaps between the electrodes. In both cases, vias are made for interconnection between the electrodes and the conductive wires. With the one-layer electrode design, both 1-diopter and 2-diopter 8-level lenses are demonstrated with an aperture of 10 mm. With the two-layer electrode design, a 2-diopter, 15-mm, 4-level lens is demonstrated. The diffraction efficiency of the 8-level lens can be higher than 90%. The ON- and OFF-state of the electrically controlled lens allow near- and distance-vision respectively for presbyopic eyes. The focusing power of the lens can be adjusted to be either positive or negative. The focusing power of the 8-level lens can be adjusted for near-, intermediate-, and distance vision. The lens is compact and easy to operate with fast response time, low voltages and low power dissipation. This is the first demonstration of the switchable lenses that almost meet the requirements for spectacle lens.