DVD surface. Coloured scanning electron micrograph (SEM) of the pits that encode information on the surface of a DVD (digital versatile disc). These pits are read by a focused laser as the disc rotates. This is a double-layer DVD, which can hold up to 8.5 gigabytes (GB) of information. This upper layer is semi-transparent and is gold in colour. A second layer (not seen), bonded to the gold layer with a clear adhesive, is coloured silver. After the laser has read the information on the gold layer (from the centre of the disc outwards), the laser refocuses itself on the silver layer and reads from that, from the outer edge inwards. Magnification: x5750 at 6x7cm size.