发明名称 |
Optical disc system having an objective lens with a numerical aperture related to the thickness of the protective layer |
摘要 |
A magneto-optical disc system includes a magneto-optical disc 40 with a light-transmitting cover layer 41, an objective lens 2 for bundling or focusing a laser beam onto a magnetic recording layer 43 of the magneto-optical disc 40 for recording information thereon and/or reproducing information therefrom, and a magnetic field generating unit 9 having a coil pattern 7 arranged on an optical glass element 8. The thickness t2 of the light-transmitting cover layer 41 falls within the range of 0.6 to 0.1 mm, and the numerical aperture (NA) of the objective lens 2 falls within the range of 0.55 to 0.70.
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申请公布号 |
US5757733(A) |
申请公布日期 |
1998.05.26 |
申请号 |
US19960613035 |
申请日期 |
1996.03.08 |
申请人 |
SONY CORPORATION |
发明人 |
WATANABE, TETSU;AOKI, YOSHIO |
分类号 |
G11B7/0037;G11B7/007;G11B7/135;G11B7/24;G11B11/105;(IPC1-7):G11B11/00 |
主分类号 |
G11B7/0037 |
代理机构 |
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代理人 |
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主权项 |
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地址 |
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