| 摘要 |
PROBLEM TO BE SOLVED: To equalize the quality of a reproduced signal when respective signal faces are reproduced in a 2-layer optical disk for executing high-density and one-side reading. SOLUTION: First signal layers 2 and 42, translucent films 4 and 44, middle layers 6 and 46, reflection films 10 and 50 and second signal layers 8 and 48 are formed in order, and the one-side readable 2-layer optical disk having signal pits on the translucent film sides of the first signal layers 2 and 42 and on the reflection film sides of the second signal layers 8 and 48 is produced. The thickness of the first signal layers 2 and 42, an aperture NA of the reproducing head H or the wavelength of a laser beam is adequately selected so that a focus position FP, where the laser beam for reading is focused most, can be set in the middle layers when the laser beam for reading from the reproducing head H is incident nearly vertically on the one-side readable 2-layer optical disk from the side of the first signal layer, and then jitters are approximately equalized when each of the signals of the first and the second signal layers 2, 42, 8 and 48 is reproduced. |
