Patent ID: 6768666
Filing Date: 2004-07-27
Classification: G02F

Abstract:
A phase angle controlled stationary element for modifying the wavefront of incident electromagnetic radiation to produce reflected electromagnetic radiation, said element comprising a phase change material, said phase change material having a crystalline state and an amorphous state, said phase change material including a plurality of data cells, said data cells having no cross-sectional dimension that exceeds the wavelength of said incident electromagnetic radiation, said data cells comprising a matrix of said crystalline state of said phase change material with one or more marks dispersed therein, each of said marks consisting essentially of said amorphous state of said phase change material, all of said marks forming a pattern in said phase change material, said pattern providing one or more crystallinity gradients, said crystallinity gradients extending over at least two of said data cells, each of said at least two data cells of said crystallinity gradient having a different fractional crystallinity, said crystallinity gradients providing a stored phase taper, said stored phase taper influencing the phase angle at two or more different positions of said incident wavefront to differing extents to provide said reflected radiation.