发明名称 |
Focus error detection using an equal path length lateral shearing interferometer |
摘要 |
This invention provides an equal path length lateral shearing interferometer and its implementation in focus detection devices, particularly for optical data storage devices. The interferometer comprises a beamsplitter and two abutting roof prisms. Shifting the placement of a roof prism along an axis orthogonal to the direction of light propagation and to the peak of the roof creates a lateral shear between the two output beams. Rotation a roof prism about this axis produces a tilt between the two output beams. This creates an interference pattern with a rotational orientation which is a function of the focus of the beam impinging on the optical storage medium. A pattern sensor is provided to adjust the focus of the beam in an accurate and dynamic manner.
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申请公布号 |
US5446710(A) |
申请公布日期 |
1995.08.29 |
申请号 |
US19920972578 |
申请日期 |
1992.11.06 |
申请人 |
INTERNATIONAL BUSINESS MACHINES CORPORATION |
发明人 |
GARDNER, TIMOTHY S.;STAHL, RONALD P.;SHAFAAT, SYED T. |
分类号 |
G11B7/09;(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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地址 |
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