| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an optical disk device capable of precisely and stably performing access to an optical disk having a plurality of recording layers, and to provide the inexpensive optical disk having a high recording capacity. <P>SOLUTION: It is set so that t≤52 n<SP>3</SP>λ/ä(n<SP>2</SP>-1)NA<SP>4</SP>} is satisfied, where t is the interval between a first recording layer M0 and a second recording layer M1, λ is the wavelength of a light flux for irradiation, n is the equivalent refractive index of an intermediate layer ML sandwiched between the first recording layer M0 and the second recording layer M1, and NA is the numerical aperture of an objective lens for concentrating the light flux. Thus, when used in the optical disk device having a prescribed aberration correction function, even when any of the recording layers is to be accessed, the spherical aberration can be made ≤0.035λ, and an optical spot superior in the shape quality can be formed. <P>COPYRIGHT: (C)2005,JPO&NCIPI |
