Optical properties of a liquid-crystal microlens with an arrayed planar non-uniform spiral micro-coil electrode

Abstract

A new type of liquid-crystal (LC) microlens with an arrayed planar non-uniform spiral micro-coil electrode is proposed. Arrayed cylindrical microbeam focusing and spherical microbeam focusing corresponding to a circular and an elliptical micro-coil are realized, respectively. By applying driving voltage signals over only one electrode plate of the proposed LC microlens, an orderly inclining of LC directors can be achieved in response to the generated electric field, and this is the first time such a method has been proposed to the best of our knowledge. Through adjusting driving voltage signals, the electrically tunable focusing properties are evaluated experimentally. Typical focusing performances such as an arrayed focal line with ${\sim} 1.75\,\,{\rm mm}$∼1.75mm focal length corresponding to a signal voltage of ${\sim}{45.6\,\,{\rm V}_{\rm rms}}$∼45.6Vrms and a focal point with ${\sim} 2.35\,\,{\rm mm}$∼2.35mm focal length corresponding to ${\sim}{55.0\,\,{\rm V}_{\rm rms}}$∼55.0Vrms are given, as well as several typical intermediate states. This research lays a solid basis for continuously developing LC microlens technology.