| 摘要 |
<p>An optical information medium comprising at least two data layers (DL-1, DL-2) for bearing recorded information, and a servo layer (SL) for bearing tracking servo information which is independently formed from the data layers (DL-1, DL-2); wherein the medium is used with a recording or reading system wherein a data beam for recording or reading the data in the data layer (DL-1 or DL-2) and a servo beam for reading the tracking servo information in the servo layer (SL) are used, and the servo layer (SL) is read by the servo beam that had passed through the data layer (LD-1, LD-2); and a filter layer (FL) is disposed between the data layer (DL-2) and the servo layer (SL); and the filter layer (FL) exhibits higher absorption to the data beam than to the servo beam.</p> |
