OPTICAL DATA STORAGE DISC

摘要

An optical data storage disc, e.g. a compact disc, has one side formed with a pattern of indentations (11) defining a digital data recording, and this side is metallised (at 12) and further coated with a layer (14) which is embossed with a relief pattern (15) defining a holographic image. The hologram may extend across the whole surface of the disc and is visible from the top side of the disc, whilst the digital information is readable in the usual way using a laser directed at the underside of the disc.