| 摘要 |
PROBLEM TO BE SOLVED: To obtain a stamper for a hybrid direct read after write optical disk never distorting the prepit shape in the PMA region at the time of molding, nor generating the defective mold. SOLUTION: This stamper is used for producing the hybrid direct read after write optical disk 31 having pregrooves 2 and prepit 4a, 4b by molding, and by making the pit length of the PMA region E3 longer so as to be different from the pit length of the PA region E5, the deformation due to the molding is corrected and the asymmetry in the PMA region E4 is reduced, resultantly is allowed to approach to the asymmetry of the information area, then the erroneous operation at the time of write once is reduced.
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