Switchable electro-optic diffractive lens with high efficiency for ophthalmic applications

TLDR

Presbyopia is an age‑related loss of accommodation that limits near‑vision, and conventional bifocal lenses restrict field of view, causing discomfort. The study reports a novel switchable, flat liquid‑crystal diffractive lens that adaptively changes focusing power. The lenses use electrically controlled refractive index of a 5‑µm nematic liquid‑crystal layer patterned with a circular array of transparent electrodes. The lenses achieve >90 % diffraction efficiency, <2 Vrms drive voltage, sub‑second response, minimal aberrations, and a power‑failure‑safe design, marking a significant advance toward automatic, adjustable presbyopia correction.

Abstract

Presbyopia is an age-related loss of accommodation of the human eye that manifests itself as inability to shift focus from distant to near objects. Assuming no refractive error, presbyopes have clear vision of distant objects; they require reading glasses for viewing near objects. Area-divided bifocal lenses are one example of a treatment for this problem. However, the field of view is limited in such eyeglasses, requiring the user to gaze down to accomplish near-vision tasks and in some cases causing dizziness and discomfort. Here, we report on previously undescribed switchable, flat, liquid-crystal diffractive lenses that can adaptively change their focusing power. The operation of these spectacle lenses is based on electrical control of the refractive index of a 5-mum-thick layer of nematic liquid crystal using a circular array of photolithographically defined transparent electrodes. It operates with high transmission, low voltage (<2 Vrms), fast response (<1 sec), diffraction efficiency > 90%, small aberrations, and a power-failure-safe configuration. These results represent significant advance in state-of-the-art liquid-crystal diffractive lenses for vision care and other applications. They have the potential of revolutionizing the field of presbyopia correction when combined with automatic adjustable focusing power.