Ectrically controlled liquid crystal twist-planar fresnel lens

Abstract

Based on the method of photo-orientation of the azo-dye AtA-2, an electrically controlled Fresnel lens has been developed which is a microstructured liquid crystal element made up of alternating rings with twist- and planar orientations of the liquid crystal director. It is shown that the use of a control voltage makes it possible to control the effi ciency of the focusing of laser radiation, as well as to turn off the lens. An optimum control voltage (~3 V) is determined at which a maximum focal effi ciency and satisfactory quality of image construction over a wide spectral range from 530 nm to 1.1 micron are attained.