The HD DVD is a digital optic data storage media format that uses a 120mm diameter disc. A single layer HD DVD has a storage capacity for 15GB data, as compared to a 4.7GB of a standard DVD. A dual layer HD DVD can store 30GB data, while a triple layer HD DVD has a 45GB capacity. The HD DVD is complemented with the HDTV or high definition television. A high definition television is a system that scans pictures with more than double the lines of resolution as compared to a standard format television. Therefore, equipped with 1,080 lines of resolution, in contrast with 480 lines for regular television and DVD players, it provides a very superior quality, high definition picture. Most of the HDTVs are wide screen to eliminate the letterbox effect and better viewing.

Structure

The HD DVD optical disc has two 120mm diameter substrates bonded back-to back, each having surface layer thickness of 0.6mm. Its optical pick-up head