| 摘要 |
<p>A recording layer (2) and a light-transmitting layer (3) are provided on a substrate (1) having a guide groove for tracking a light beam projected in a spot for information recording/reproduction. The spot light beam is projected onto the recording layer (2) through the light-transmitting layer (3) so as to record information in a first portion (G') of the recording layer corresponding to the inside (G) of the guide groove and a second portion (L') of the recording layer corresponding to a flat portion (L) between adjacent guide grooves. The depth d of the first portion (G') with respect to the second portion (L') on the light-transmitting layer side of the recording layer (2) satisfies the relation λ/5.8nf ≤ d ≤ λ/5nf where λ is the wavelength of the light and nf is the index of refraction of the light-transmitting layer (3) to the wavelength X. The reflectance of the recording layer (2) after the recording is larger than that before the recording.
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