发明名称 |
Focus-error detection using prism-enhanced spot size monitoring |
摘要 |
An apparatus and method is described for detecting focus errors in an optical head by positioning a prism in the optical path of a return light beam reflected from an optical recording medium. The prism reduces the beam in one dimension by a factor of M and concurrently increases the divergence/convergence angle associated with a focus-error of the beam by a factor of M in this dimension, thereby desirably enhancing the focus error signal by a factor of M2. A focus error is detected by a segmented photodetector having inner and outer photosensitive regions. The photodetector generates an electrical signal indicative of the focus error from the difference in light intensities at the inner and outer regions. The photodetector preferably is segmented in such manner as to also provide a track error signal.
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申请公布号 |
US5084783(A) |
申请公布日期 |
1992.01.28 |
申请号 |
US19900511664 |
申请日期 |
1990.04.20 |
申请人 |
INTERNATIONAL BUSINESS MACHINES CORPORATION |
发明人 |
DEWEY, ANTHONY G.;LENTH, WILFRIED;RUGAR, DANIEL |
分类号 |
G02B7/28;G11B7/09;G11B7/13;G11B7/135 |
主分类号 |
G02B7/28 |
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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