US Patent 7570427 Geometrical phase optical elements with space-variant subwavelength gratings

A space variant polarization optical element for spatially manipulating polarization-dependent geometrical phases of an incident light beam. The element comprises a substrate with a plurality of zones of gratings with a continuously varying orientation. The orientation denoted by θ(x-y) is equal to half of a desired geometrical phase (DGP) modulus 2π. Each grating has a local period that is smaller than the wavelength of the incident light beam. In other embodiments of the present invention the substrate comprises a plurality of zones of gratings with a continuously varying orientation.