| 摘要 |
PROBLEM TO BE SOLVED: To reduce reading errors by reducing a level difference of reproduced signal levels according to pit length. SOLUTION: A pit is formed by varying pit depth according to the pit length. For example, when the pit is formed by setting the longest pit as shallower than λ/4, the pit is formed by setting the pit depth deeper as the pit length becomes shorter. In addition, when the pit is formed by setting the longest pit as deeper than λ/4, the pit is formed by setting the pit length shallower as the pit length becomes shorter. In both cases, the pit is optimally formed by setting the pit depth of the shortest pit to λ/4. |
