Patent ID: 6088161
Filing Date: 2000-07-11
Classification: B42D,G03H

Abstract:
A diffractive device having a surface relief structure which, when illuminated by a light source, generates two or more diffraction images which are observable from different ranges of viewing angles around the device, wherein at least part of the surface relief structure is arranged in a series of tracks, each track being less than 0.25 mm in width and greater than 0.5 mm in length and having a diffracting surface relief structure comprised of individual structure elements, the surface relief structure being substantially discontinuous between adjoining tracks but continuous within each track, wherein ""continuous"" means that there are no substantial differences between adjacent individual structure elements in terms or orientation curvature and spacing, and wherein the surface relief structure of each track generates a component of a diffraction image, such that a first group of the tracks generates one of the diffraction images, and a second group of tracks interspersed with the first generates a second diffraction image, each image comprising regions of a multiplicity of different colours and/or intensities.