Switchable large-aperture liquid-crystal diffractive lenses

Abstract

Switchable large aperture liquid crystal Fresnel diffractive lenses with aperture diameters of 20-30 mm were designed, fabricated, and demonstrated experimentally with multiple 2 pi radian phase modulation in each Fresnel zone. The structure design with multiple 2 pi radian phase modulation in each Fresnel zone can reduce difficulty in micro-fabrication of the lenses. The influence of electrode gaps of Fresnel lenses on their diffraction efficiencies was examined by numerical analysis. The lenses showed fast switching speed, low driving voltages (<2 V), and high diffraction efficiencies (>62%). They have potential to be applied for autofocus imaging devices and adaptive optics system.