HERSTELLUNGSVERFAHREN FÜR EINE RÄUMLICH VERÄNDERLICHE FLÜSSIGKRISTALL-VERZÖGERUNGSPLATTE

The invention provides a space-variant liquid-crystal (LC) photo-aligned waveplate having a vortex optic axis pattern, and an apparatus and method for fabricating thereof. The method in it preferred embodiment includes exposing a substrate (15) coated with a photo-alignable material (20) such as LPP to linearly polarized UV radiation (111) through a wedge-shaped aperture (125), while rotating two of the aperture (125), the substrate and the polarization of the UV light, so that an exposure area performs a full rotation about a center point on the substrate, at angular velocities selected so as to form a vortex alignment pattern of a pre-defined order. An LC material is then deposited on the substrate in direct contact with the photo-alignable material (20) so that the LC director is aligned according to the photo-induced vortex alignment pattern. The method enables to fabricate vortex waveplate of any pre-defined vortex order.