VARIABLE DEVICE EXHIBITING NON-DIFFRACTIVE THREE-DIMENSIONAL OPTICAL EFFECT

摘要

An optically variable device includes a substrate and a plurality of optical elements formed in or on the substrate and being structured to provide a three- dimensional optical effect for a viewer when light is incident on the optical elements. The plurality of optical elements are arranged as a plurality of stereo pairs structured to reflect or refract Sight to corresponding focal points in three-dimensional space apart from the optically variable device to form the three-dimensional optical effect. The optical elements include one or more optical elements that are curved structures having a curvature that is either less than or greater than a semi-circle.