DIFFRACTION-BASED OPTICAL GRATING STRUCTURE AND METHOD OF CREATING THE SAME

摘要

Optical elements include an optical grating structure (22) which exhibits novel pleochroic properties when rotated or viewed from changing observation locations. The optical grating structure is formed from a plurality of selectively arranged grating elements which are preferably, but not necessarily, formed from a plurality of lines or grooves (24) having a closed loop shape. The preferred closed loop lines and grooves are disposed one inside another and preferably include at least one common axis of symmetry. A two-­dimensional array (50) of such elements is arranged to define an optically variable device. A method of creating elements, arrays and optically variable devices and articles employing the same are also disclosed.