Large-aperture switchable thin diffractive lens with interleaved electrode patterns

The authors report on a high-performance large-aperture switchable diffractive lens using nematic liquid crystal that can be used as an adaptive eyewear. The odd- and even-numbered ring electrodes are separated in two layers, avoiding the gaps between the neighboring electrodes and allowing high diffraction efficiency. It is easier to avoid shorts between neighboring conductive electrodes and fabricate lenses with larger aperture and smaller feature size. With a four-level phase modulation, a 15 mm aperture, 2 dpt lens with small aberrations and diffraction efficiency of above 75% could be demonstrated with low operating voltages. The thickness of the liquid crystal is only 5 μm. The lens switching time is about 180 ms. The on and off states of the electrically controlled lens allows near and distance vision, respectively. The focusing power of the lens can be adjusted to be either positive or negative. This structure can be extended to higher-level phase modulation with even higher efficiencies.