INFORMATION RECORDING MEDIUM, INFORMATION RECORDING AND REPRODUCING DEVICE, AND INFORMATION RECORDING AND REPRODUCING METHOD

摘要

PROBLEM TO BE SOLVED: To optimize the thickness of a light transmission layer of an information recording medium having three or more recording layers by taking correction of spherical aberration on a recording and reproducing device side into consideration.

SOLUTION: In the recording medium being an optical disk 100 wherein a plurality of information recording layers are layered while interposing intermediate layers each having light transmission property among them on a substrate 101 and the light transmission layer is further layered thereon, the thickness and the refractive index between a disk surface and an information recording layer 106 or 102 having a thickness most separated from the standard value of the thickness of the information recording layer from the disk surface are so set that the thickness is in the range of ±37 μm of a standard value to be the upper limit of aberration permitted to all the light transmission layers and the intermediate layers from the disk surface to the information recording layer having the thickness most separated from the standard value of the thickness in the information recording layer and the refractive index is in the range of 1.5 to 1.7. A lens radiating laser beam made incident on the light transmission layer has a numerical aperture of 0.65 and the laser beam has 395 to 415 nm wavelength.

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