US Patent 7126730 Electro-holographic lens

An electro-holographic lens device comprising: an active layer made from a transparent photo-refractive material, whose refractive index may be locally modified by locally applying an electric field; an array of electrodes in a predetermined density, provided adjacent the active layer for locally providing electric fields across an array of predetermined locations in the active layer; and a control unit for applying and controlling application of electric fields in a dynamically controllable predetermined locations for creating a holographic fringe pattern across the active layer.