The digital video signal can be stored magnetically or optically. Optical media is a development of the digital domain. It is not used for analog recording or storage, only for recording or storing digital data. The primary difference between magnetic and optical media is that magnetic media are volatile, meaning that the information can be lost accidentally by exposure to a strong magnetic field. Optical media, on the other hand, are non-volatile. The data, once recorded, cannot be changed or erased except through direct action by the user.
All optical media use laser technology for recording, storing, and reproducing digital data. There are three primary components of a laser system: a laser, a lens, ...