Dynamic information storage or retrieval – With servo positioning of transducer assembly over track... – Optical servo system
Patent
1991-12-05
1993-08-31
Sniezek, Andrew L.
Dynamic information storage or retrieval
With servo positioning of transducer assembly over track...
Optical servo system
369 4441, 369110, 369 13, G11B 700, G11B 2110
Patent
active
052415236
ABSTRACT:
Focus apparatus is disclosed for use as a focus error detector in an optical system. The apparatus comprises two polarizer elements of different polarization disposed at the pupil of a focusing lens. A detector is positioned at an image plane to intercept a beam from the lens and polarizer elements. The detector includes a detector element which is adapted to detect radiation in four quadrants, and an analyzer which is disposed in front of the detector element. The analyzer includes two polarizers of different polarization arranged at right angles to the polarizers disposed at the pupil of the lens. An electronic circuit is coupled to the detector for producing a focus error signal.
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Eastman Kodak Company
Randall Robert L.
Sniezek Andrew L.
Tran Thang V.
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