MODEL RELEASED. Compact disc manufacture. Time- exposure image of a technician visually inspecting new compact discs (CDs) on the conveyor belt of a production line as part of quality control. CDs store data (such as music, text or images) as a series of fine depressions on the disc's plastic surface, representing a digitised signal capable of being read by a laser. To reflect the laser light, the coded layer is coated with a fine film of metal which follows the depressions exactly. This is then covered by another layer of transparent plastic which prevents dust and scratches from affecting the readout. Audio compact discs have high sound quality.