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Ahstrart: This report is on a 150 GB &layer write once disc with the newly developed recording materials for Blu-ray Disc system. We achieved the optimum recording powers and the jitter values less than 16.0 mW and 8.0 % for each layer at the user data recording rate of 72 Mhps. This result shows feasibility of realization of 6layered recordable Blu-ray disc.

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We made improvements on the previously reported hard-coat for cartridge-free Blu-ray disc from a viewpoint of an antifingerprint property. As a result of this study, two types of the hard-coat have been obtained. One is for Blu-ray discs of ROM and write-once types, and the other is for that of rewritable type. The former well inhibited a deterioration of bit error rate (bER) of the signal written prior to the fingerprint adhesion. The later exhibited low bER for the data signals written both before and after the fingerprint adhesion. These results are attributable to the area ratio of drops of fingerprint-ingredient on the disc surface, and the low area ratio resulted in a low bER. Moreover, it was confirmed that the disc with higher contact angle of oily compound exhibited the lower area ratio ofthe fingerprint.