How does a DVD player read DVDs?

Answer 1

The DVD Player works a bit like the old record player. The principles include Laser Reads the Disc, Motor Spins the Disc and Device Measures Tracks.

The laser light is shone onto the disc and as it spins, minute dents in the internal metal disc are reflected back. A photo transistor or diode, pick up the reflected light as 1's and 0's. This is fed to a computer which reassembles the digital code through a digital to analogue converter and feeds it to an audio amplifier. The sound can then be heard through headphones or speakers.

In the meantime other functions of the computer control the speed of rotation of the disc, the focus of the laser, the tracking of the laser mounting, to follow the spiral series of indentations in the disc and error correction.