| 摘要 |
PURPOSE: An optical disk is provided to obtain a reproduced signal by a recorded mark, a reproduced signal by a pre-pit, both large reproduced signals, and large tracking signals in both groove part and pre-pit part, and to have enough time when a tracking method is switched in the groove and pre-pit parts. CONSTITUTION: A tracking including recordable grooves(G) and pre-pits(PP) deeper than the grooves is formed at least on a substrate. A shallow pit region having a relatively long length is provided between the deep pit region and the groove region. An arrangement is made such that the depth(Dg) of the groove, the depth(Dsp) of the shallow pit and the depth(Ddp) of the deep pit satisfy a relation of Dg<λ/(8n),λ/(8n)<Ddp<λ/(4n) and Dg <= Dsp. A tracking method is switched in the shallot pit region during recording/playing. |
