| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an optical disk apparatus of low costs capable of stably performing playback or recording of each signal surface of an optical disk having a multilayered structure having a plurality of signal surfaces and attaining high density and having high capacity and a small size. <P>SOLUTION: In the optical disk apparatus performing playback or recording of the optical disk 10 having the multilayered structure provided with a substrate 11, the plurality of signal surfaces 12 and 14 layered on the substrate 11 via an intermediate layer 13 and a protective layer 15 on the surface of the plurality of signal surfaces 14 and 15, recording or playback of information is performed by focusing light from a laser light source 21 emitting light having 350 to 500 nm wavelength on the optical disk 10 wherein refractive index n<SB>1</SB>of the intermediate layer 13 is lower than the refractive index n<SB>2</SB>of the protective layer 15 by using an objective lens 25 having a numerical aperture of 0.70 to 0.75. <P>COPYRIGHT: (C)2006,JPO&NCIPI |
