发明申请
- 专利标题: PHASE PLATE AND OPTICAL HEAD DEVICE
- 专利标题(中): 相位板和光头设备
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申请号: US11874547申请日: 2007-10-18
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公开(公告)号: US20080044125A1公开(公告)日: 2008-02-21
- 发明人: Toshimasa Kakiuchi , Koichi Murata
- 申请人: Toshimasa Kakiuchi , Koichi Murata
- 申请人地址: JP Chiyoda-ku
- 专利权人: ASAHI GLASS COMPANY LIMITED
- 当前专利权人: ASAHI GLASS COMPANY LIMITED
- 当前专利权人地址: JP Chiyoda-ku
- 优先权: JP2005-122609 20050420
- 主分类号: G02F1/035
- IPC分类号: G02F1/035
摘要:
A phase plate and an optical head device are provided, which are capable of suppressing changes of the amount of light incident on a light-receiving unit even if the phase difference caused by transmission through a protective layer of an optical recording medium differs depending on the type of optical recording medium. The phase plate includes a birefringent medium and produces a phase difference in linearly polarized light incident on the phase plate between a polarization component having a polarization direction parallel to the optic axis of the birefringent medium and a polarization component having a polarization direction perpendicular to the optic axis. In the phase plate, the birefringent medium includes a plurality of types of phase areas disposed adjacently; at least two types of adjacent phase areas are different from each other in phase differences, optic axes, or both phase differences and optic axes; and each of the plurality of types of phase areas is disposed so as to have two-fold rotational symmetry with respect to the optical axis of the phase plate.
公开/授权文献
- US07782738B2 Phase plate and optical head device 公开/授权日:2010-08-24