Optical device with electrodes end-to-end with electric field causing homeotropic alignment of liquid crystal in space between ends

摘要

An electrically-controllable wave plate comprises a layer of liquid crystal material having positive dielectric anisotropy, the layer being contained between two transparent plates. An alignment layer is provided on each plate for causing homeotropic alignment of the LC molecules adjacent the plate. Electrodes are so positioned that they apply an electric field substantially along the plane of the LC layer so that the molecules acquire variable tilt through the thickness of the layer, resulting in birefringence of the layer. The wave plate may be used in a polarisation controller.