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

Claim 1

An electrically-controllable liquid crystal wave plate comprising a layer of liquid crystal material having positive dielectric anisotropy, the layer being contained between two transparent plates; a respective alignment layer on each plate for causing homeotropic alignment of the molecules of the liquid crystal material adjacent the respective plate; and electrode means electrically-energizable to apply an electric field in the layer of liquid crystal material whereby the molecules acquire variable tilt through the thickness of the layer of liquid crystal material, resulting in birefringence of the layer, wherein the electrode means comprises at least one pair of first conductors disposed end-to-end substantially in the plane of the layer of liquid crystal material with a space therebetween in which the electric field is generated.