Wide aperture (50 mm), compact and high-quality continuous focus tunable Gradient Refractive Index (GRIN) liquid crystal lenses

Abstract

Continuous tunable lenses have significant prospect to replace conventional bulky fixed power lens system. However, lightweight, fast response, large aperture (⪆1 cm) tunable lens system remained an active challenge in the field of adaptive optics. While many approaches have been reported so far, very few can be realized for practical application of optics that requires large aperture size tunable lenses. Gradient Refractive Index (GRIN) liquid crystal lenses are one of approach which gives good control over the continuous tunability, however, large aperture device suffers from very low switching speed. In this paper, without compromising the switching speed, we are reporting 5 cm aperture size GRIN liquid crystal based continuous tunable focus lens. Reported approach implements Fresnel lens like parabolic shaped segmented phase profile instead of continuous phase, which is obtained from segmented voltage distribution. The designed lens is flat, fast switching (⪅500 ms), thin (⪅ 2 mm), light weight (⪅ 10 gm), low voltage driven (⪅ 5 V), also tunable continuously between positive to negative power. Such compact system with good optical quality scopes for potential application in eyeglasses to solve presbyopia, accomodation-convergence mismatch issue in emerging head mounted display technology, and many other imaging systems.