Yoshitsugu Araki

The Path from a Digital Versatile Disc (DVD) using a Red Laser to a DVD using a Blue Laser

The next generation digital versatile disc(DVD) using a blue laser is required to have 15 Gbytes capacity so that it can reproduce motion picture expert group 2(MPEG2) video stream with a main profile at a high level format for a maximum of 133 min. To achieve this goal, further improvements are necessary in both the recording and the reproducing systems. For the recording system the authors developed a super resolution recording material and an electron beam recording system. For the reproducing system the authors devised four technologies: a Viterbi decoder, a liquid crystal tilt servo system, a cross talk cancel system and a tangential adaptive equalizer. By combining these with a pick up head of 430 nm vavelength/0.6 NA lens and a 0.6-mm-thick substrate, the authors confirmed sufficient tilt margins in the case of 12.7 Gbytes (radial tilt margin: ±1.61°, tangential tilt margin: ±0.48°). Our next target is to work on the 15 Gbytes capacity.