High-efficiency switchable flat diffractive ophthalmic lens with three-layer electrode pattern and two-layer via structures

A general design for switchable, flat, liquid crystal diffractive lens with three-layer electrode pattern and two-layer via structures is reported for near-, intermediate-, and distance-vision corrections of presbyopic eyes. The microfabricated transparent concentric ring electrodes are distributed in two layers and different voltages are applied to each electrode through bus lines in another layer. Connection between the electrodes and the bus lines is achieved by vias (conducting holes for vertical interconnections) in the third dimension. For demonstration, a lens is first tuned with a focal length of 1 m (1 diopter add power), eight-level phase modulation, and diffraction efficiency above 92% and then reconfigured to operate as a 2 diopter four-level lens with a diffraction efficiency of 78%. The lens operates with low voltages and a rise time of 150 ms. This design methodology allows the aperture needed for practical use and a power-failure-safe configuration.