| 摘要 |
PURPOSE:To reduce the effect of contraction after forming and to increase the recording capacity than that of a conventional optical disc by forming pits or grooves to at least a part or both of regions opposite at least to a part of a non-recording region or that at the rear side. CONSTITUTION:In order to avoid deformation of pits or grooves, it is important to eliminate contraction of a non-recording region and it connects to elimination of contraction at the recording region. Thus, bits or grooves independently of signal are engraved on at least a part of the non-recording region 2, preferably to the entire region of the non-recording region 2. Further, since a stamper has a larger diameter than the disc, it is desired to give engraving to the peripheral part 4 of the non-recording region 2 of the stamper taking generation of contraction after forming into account.
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