| 摘要 |
<P>PROBLEM TO BE SOLVED: To specify ranges of the thickness of a light transmission layer and the refractive index of the light transmission layer which are effective in a next generation optical disk, and to provide an optical disk suitable for high-density recording. <P>SOLUTION: The refractive index of the light transmission layer of the optical disk is set so as to be in a range of 1.52-1.72; the numerical aperture of a lens for irradiation with a laser beam incident on the light transmission layer is set at 0.65, and the wavelength of the laser beam is set so as to be in a range of 395-415 nm. The thickness t of the light transmission layer is set so as to be in a range as f(n)-t1≤t≤f(n)+t2, using constants t1 and t2 determined on the basis of the permissive value of aberration and a function f(n) of the refractive index n, so that the aberration is within a specified permissive value. <P>COPYRIGHT: (C)2005,JPO&NCIPI |
