Patent ID: 6369919
Filing Date: 2002-04-09
Classification: B42D,G03H,Y10S

Abstract:
A holographic security debice comprising first and second holographic image generating microstructure, each structure having been originated by creating an intermediate first hologram from a respective object and a first reference beam, the two first intermediate holograms then having been illuminated with respective transfer beams which were the conjugates of the corresponding first reference beams to reconstruct their respective objects as holographic images which were then used to record the first and second holographic image generating structures on a common holographic recording medium through the process if optical interference with a second reference beam, wherein the microstructures are recorded in respective sets of substantially non-overlapping regions of the recording medium, the regions of one set being interleaved with regions of the other set, whereby the dimensions and pattern of the interleaving is substantially non-resolvable to the unaided eye, whereby the holographic security device generates two visually distinct holographic images viewed from separate viewing directions around the device and normally seen by tilting the device, and whereby each particular holographic image in viewing direction is generated structure associated with one or other set of interleaved region.