Mullti-stack optical data storage medium and use of such medium

摘要

A multi-stack optical data storage medium ( 30 ) for recording using a focused radiation beam ( 40 ) having a wave-length ? and entering through an entrance face ( 41 ) of the medium ( 30 ) is described. It has a first substrate ( 31 a) with present on a side thereof a first recording stack ( 33 ) named L0, comprising a recordable type L0 recording layer ( 35 ), and formed in a first L0 guide groove ( 38 ). The L0 recording layer ( 35 ) has a thickness dL0G in the groove ( 38 ) and a thickness dL0L adjacent the groove ( 38 ). A second substrate ( 31 b) has present on a side thereof a second recording stack ( 32 ) named L1 comprising a recordable type L1 recording layer ( 34 ). The L1 recording layer has a thickness dL1G in the groove and a thickness dL1L adjacent the groove. The second recording stack ( 32 ) is present at a position closer to the entrance face ( 41 ) than the L0 recording stack ( 33 ) and is formed in a second L1 guide groove ( 37 ). The depth of the first L0 guide groove ( 38 ) is smaller than 0.15? and dL0L is substantially equal to or larger than dL1G by which it is achieved that the L0 stack ( 33 ) has a reflection level and a modulation level of recorded marks compatible with the dual layer DVD-ROM specification.