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