OPTICAL DISK DEVICE AND OPTICAL DISK

摘要

PROBLEM TO BE SOLVED: To provide a multilayered optical disk which is made highest in storage capacity with a permissible tilt angle and the spacing between recording layers as parameters and an optical disk device dealing with such multilayered optical disk.

SOLUTION: The optical disk device is equipped with an objective lens for irradiating the optical disk having five or more layers of the laminated recording layers with light and a tilt adjusting mechanism formed between the optical axis of the light and the normal of the recording layers to control the tilt angle and performs writing of data to the recording layer selected from a plurality of the recording layer on the optical disk and/or reading out of the data recorded to the recording layer selected from the plurality of the recording layers and the numerical aperture NA of the objective lens is so determined that the distance between the recording layer arranged in the position remotest from the photoirradiated side face of the optical disk and the photoirradiated side face of the optical disk, defined as D mm, satisfies a relational expression 1.3009xD3-2.9315xD2+2.3133xD-0.0502≤NA≤1.3009xD3-2.9315xD2+2.3133xD+0.2028.

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