Patent ID: 8319908

Claim:
A variable optical device for controlling the propagation of light passing through the device, said optical device comprising: at least one liquid crystal cell, each liquid crystal cell including: substrates; a liquid crystal layer through which said light passes, optical properties of said liquid crystal layer controlling said light propagation; and alignment layers on said substrates and in contact with liquid crystal material of said liquid crystal layer; a complex frequency electrical signal generator configured to generate a plurality of component drive signals having different pre-determined frequencies and combining said component drive signals into a complex frequency drive signal; and an electric field control structure arranged to apply said complex frequency drive signal to generate an electric field acting on said at least one liquid crystal layer with a spatial profile dependent on frequency and amplitude of said drive signals, said electric field control structure including: a first electrode for each said liquid crystal cell located to one side of said liquid crystal cell; at least one hole-patterned electrode defining an aperture of said optical device; and a weakly conductive material extending across said aperture.