OPTICAL DISK

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PROBLEM TO BE SOLVED : To provide an optical disk wherein one or more rewritable recording layers and non-rewritable recording layers are respectively provided to enhance user convenience. SOLUTION : In the optical disk having a plurality of recording layers capable of recording and reproducing information using a laser beam on a transparent disk substrate 2 having guide grooves formed thereon and irradiated with the laser beam from only the disk substrate side, the plurality of recording layers respectively include at least one rewritable recording layer 4 and at least one non-rewritable recording layer 8 and the rewritable recording layer comprises a phase transition material reversibly generating change between an amorphous phase and a crystal phase by irradiation with the laser beam or a rare earth-transition metal based magneto-optical material. COPYRIGHT : (C)2007, JPO&INPIT