Patent ID: 8879371
Filing Date: 2014-11-04
Classification: G11B

Abstract:
1. A recording medium comprising: a guide layer on which a guide track or guide tracks for tracking are formed; and a plurality of recording layers laminated on the guide layer, wherein, a same mark group is formed in a same rotational phase position of each of at least two guide tracks out of a plurality of guide tracks which are included in a beam spot at the same time which is formed on the guide layer by guide laser light irradiated on the guide layer, the mark group includes a pair of record marks which are shifted by a predetermined distance toward a right side and a left side, respectively, from a track center of the each guide track, and a depth of the pair of record marks is less than λ/6n, where λ is a wavelength of the guide laser light and n is a substrate refractive index of the recording medium.