: Microscopic depressions called pits and flat areas called lands are pressed into the plastic.
A standard audio CD is a 120 mm (4.7 in) circular disc composed of several layers: audio compact disc
CD players use a to scan the disc from the center outward along a spiral track. When the laser hits a pit , it scatters the light; when it hits a land , the light is reflected back to a sensor. The sensor translates these light changes into electrical signals (zeros and ones), which are then converted back into high-fidelity audio. The Compact Disc: An Introduction : Microscopic depressions called pits and flat areas
: A 1.2 mm thick layer of clear polycarbonate plastic . The sensor translates these light changes into electrical
: A film of acrylic lacquer seals the reflective layer to prevent corrosion and physical damage. How It Works