| 摘要 |
PROBLEM TO BE SOLVED: To provide a multilevel optical data-storage medium having an adequate asymmetry. SOLUTION: In the multilevel optical data-storage medium, multilevel recording to its one virtual record cell is possible. In addition, the asymmetry between the virtual record cell S0 to which the first information is recorded and the virtual record cell S7 to which the second information different from the first information is recorded is set in a rage of -20% to 20%. By this, a symbol error rate (SER) can sufficiently be reduced. Furthermore, a bit error rate (BER) can sufficiently be reduced by setting the asymmetry in a range of -15% to 10%. |
