Patent ID: 6833956
Filing Date: 2004-12-21
Classification: B42D,G02B,G03H

Abstract:
A diffractive device having a surface relief structure which, when illuminated by a light source, generates one or more diffraction images which are observable from particular ranges of viewing angles around the device, including:a region of diffractive structural elements, the region having a length and a width; background diffractive structural elements distributed over the length of the region, a plurality of the background elements having a longitudinal extent which extends throughout the width of the region; and a plurality of interstitial diffractive structural elements; the interstitial elements being interspersed between the background elements such that each of the plurality of interstitial elements are interspersed at least partially longitudinally alongside a background element or alongside another interstitial element that extends alongside a background element such that the background elements extend into and between the interstitial elements, within the region, whereby the diffractive action of the background elements is modulated by the interstitial elements, with differing interstitial element configuration in differing parts of the surface relief structure producing differing diffraction effects in corresponding parts of the diffraction images.