发明授权
US5889748A Object lens and optical head for reproducing data from optical disks in
different thickness of substrate
失效
对象透镜和光学头,用于从不同厚度的基板的光盘再现数据
- 专利标题: Object lens and optical head for reproducing data from optical disks in different thickness of substrate
- 专利标题(中): 对象透镜和光学头,用于从不同厚度的基板的光盘再现数据
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申请号: US772874申请日: 1996-12-26
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公开(公告)号: US5889748A公开(公告)日: 1999-03-30
- 发明人: Takeshi Shimano , Masayuki Inoue , Akira Arimoto , Hiroyuki Minemura , Hisao Fujita , Hideaki Koyanagi
- 申请人: Takeshi Shimano , Masayuki Inoue , Akira Arimoto , Hiroyuki Minemura , Hisao Fujita , Hideaki Koyanagi
- 申请人地址: JPX Tokyo JPX Tokyo
- 专利权人: Hitachi, Ltd.,Hoya Corporation
- 当前专利权人: Hitachi, Ltd.,Hoya Corporation
- 当前专利权人地址: JPX Tokyo JPX Tokyo
- 优先权: JPX7-342203 19951228
- 主分类号: G02B13/00
- IPC分类号: G02B13/00 ; G11B7/00 ; G11B7/125 ; G11B7/135
摘要:
The objective lens has a numerical aperture NA=0.6 when reproducing a DVD having a thickness of 0.6 mm and NA=0.42 when reproducing a CD having a thickness of 1.2 mm. At a boundary of NA 0.42, a slight stepped portion is formed so as to establish a phase difference. In this case, a designed wavelength is 0.635 .mu.m, and an optimum designed substrate thickness of a central portion is approximately 0.8 mm. While the DVD is reproduced, wave front aberration is on the order of 0.025.lambda., and jitter contained in the reproduction signal of the CD is equivalent to the present jitter. As a consequence, such an objective lens and an optical head with employment of this objective lens are provided, which precisely reproduce signals from the CD having the substrate thickness of 1.2 mm, and the DVD having the substrate thickness of 0.6 mm.
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