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

摘要

A multi-stack optical data storage medium, for recording using a focused radiation beam having a wavelength lambda and entering through an entrance face of the medium, has a first substrate having a first guide groove formed therein, and a first recording stack including a recordable type recording layer having a thickness d_L0G in the groove and a thickness d_L0L adjacent the groove. A second substrate has a second guide groove formed therein, and a second recording stack including a recordable type recording layer having a thickness d_L1G in the groove and a thickness d_L1L adjacent the groove. The second recording stack is at a position closer to the entrance face than the first recording stack. The depth of the first guide groove is smaller than 0.15 lambda and d_L0L is substantially equal to or larger than d_L1G.