Optical disk is one of the most dense information storage devices in recent years. Its basic principle is to use a focused laser beam to optically read and write on a storage medium.

Optical disc is actually a circular thin sheet made of composite materials, and C D records, V C D and D VD discs available in the market also belong to the category of optical discs. The signals recorded on the optical disc are binary information mixed by FM video signals and audio signals, namely "0" and "1" signals. The laser beam of this signal is used to etch the master disk. When playing an optical disc, the laser can read out the binary data according to the difference between the reflected signals of pits and non-pits, and then restore it to video signals and audio signals.