发明名称 |
Focus detector for optical apparatus |
摘要 |
An optical disk recorder focus-error system includes a so-called "knife-edge" focus detector. The dynamic range of the detector is enlarged by placing an apertured mask intermediate the knife edge and the source of the light beam being focused. The knife-edge mask and the apertured mask can be deposited opaque films on a lens.
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申请公布号 |
US4672188(A) |
申请公布日期 |
1987.06.09 |
申请号 |
US19850762237 |
申请日期 |
1985.08.05 |
申请人 |
INTERNATIONAL BUSINESS MACHINES CORPORATION |
发明人 |
COHEN, DONALD K. |
分类号 |
G11B7/09;G11B7/135;(IPC1-7):G11B7/00 |
主分类号 |
G11B7/09 |
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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