Improvement of Optical Properties and Beam Steering Functions in a Liquid Crystal Microlens with an Extra Controlling Electrode by a Planar Structure

A new type of liquid-crystal microlens with an extra controlling electrode has been proposed for precise control of the refractive index distribution properties. The extra electrode is fabricated on a substrate outside of the conventional driving electrode in the planar structure. Fundamental optical properties, that is, the refractive index distribution and focusing properties, are investigated by using a cylinder lens which has a striped electrode structure. Variable focusing and beam steering functions are enhanced by using the additional electrode with an appropriate driving method. The improvement of the lens property is very effective particularly in the deformed electrode structure which deviates from the optimum conditions, and this finding facilitates designing of an optical system using the liquid crystal (LC) microlens for application in various fields. The beam steering range can also be extended without extreme degradation of the lens quality with some assistance from the external electrode. The extra electrode structure is also introduced in the LC microlens, and the same advantages as with the cylindrical lens can be obtained.