Optical security device

Abstract

A holographic effect generating structure (HEGS), either stand alone or integrated with a security diffractive image, generates a holographic optically varying image by a process of diffraction of light, this image under white light illumination generates a smoothly and continuously variable structureless optically variable apparent motion effect which moves along a pre-determined track within pre-determined limits, the device characterized that it generates 3 planes of images under white light illumination—an image plane image located at or near the image plane corresponding to the real plane of the device which defines the predetermined movement track of the apparent motion effect and its bounds, a second virtual image plane situated away from the image plane of the device forming a virtual viewing zone corresponding at which an observer would be positioned to observe the visual effect and a third image plane, which defines a region where all the light rays from the image plane artwork to the viewing zone pass through or appear to originate from which defines the defines the viewing track of the apparent motion effect.

Dependencies are inferred from the claim text.