| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an optical information recording medium wherein spherical aberration of a protective layer consisting of a plurality of layers is reduced in comparison with that in the conventional art to enable normal recording and/or reproduction. <P>SOLUTION: In an optical disk 7 having the protective layer 4 comprising a plurality of layers of a sheet layer 1, a coating layer 2, an adhesive layer 3 and the like, the ranges of the refractive index and thickness are newly defined and the refractive index and thickness of the protective layer 4 are determined in these ranges. Thereby, even if variation in thickness of the protective layer 4 is tolerated within ±3 μm, spherical aberration in the optical disk 7 can be substantially reduced to within 30 mλrms. <P>COPYRIGHT: (C)2005,JPO&NCIPI |
