Question:How does a CD work?
Diagram explaining how a CD stores information and how that information is read by a laser.
The bottom of a CD is shiny because it is a plastic protective layer over a reflective metal layer.
In the metal layer a series of pits are created in a circular pattern.
A laser beam is focussed to a small spot and then scanned across the surface of the disc.
The laser is not reflected to the detector when it hits a pit and so a pattern of on and off signals is recorded by the detector as the laser scans across a series of pits and the spaces between the pits (called lands).