发明授权
- 专利标题: Optical information processing apparatus and method of controlling position of optical spot and reproducing signals
- 专利标题(中): 光信息处理装置和控制光点位置和再现信号的方法
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申请号: US772443申请日: 1991-10-07
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公开(公告)号: US5490133A公开(公告)日: 1996-02-06
- 发明人: Shigeru Nakamura , Mariko Umeda , Takeshi Nakao , Akira Arimoto
- 申请人: Shigeru Nakamura , Mariko Umeda , Takeshi Nakao , Akira Arimoto
- 申请人地址: JPX Tokyo
- 专利权人: Hitachi, Ltd.
- 当前专利权人: Hitachi, Ltd.
- 当前专利权人地址: JPX Tokyo
- 优先权: JPX2-266205 19901005; JPX2-284246 19901024
- 主分类号: G11B7/007
- IPC分类号: G11B7/007 ; G11B7/09 ; G11B7/125 ; G11B7/135 ; G11B11/105 ; G11B7/00
摘要:
An optical information processing apparatus comprising a diffraction grating for producing a zero-order beam which is a beam emitted by a light source and allowed to pass therethrough and two plus and minus first-order sub-beams respectively having positive and negative astigmatisms, radiated in directions at slight angles different from the main beam, wherein said two sub-beams are focused at opposite positions across said main beam, wherein focusing control is performed by a focusing error signal detected from a difference of signal amplitudes obtained from the respective reflected light quantities of said two sub-beams and wherein tracking control is performed by an off-track signal obtained from a signal according to a reflected light quantity of said main beam. In an apparatus for magneto-optically reproducing information, above all else, a wave plate is inserted between the focusing lens and the separating optical system, thereby increasing the reflected light quantities and stabilizing the magneto-optical signal, focusing signal and tracking signal.