Diffractive stack pickup head for optical disk drives and method to fabricate the pickup head
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United States of America Patent
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Jun 10, 2003
Grant Date -
May 9, 2002
app pub date -
Oct 29, 2001
filing date -
Nov 4, 1999
priority date (Note) -
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status (Latency Note)
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Abstract
The invention provides a pickup head used in an optical data storage system. The pickup head contains a diffractive optical element (DOE) stack on a semiconductor substrate. The DOE stack includes multiple diffractive lenses for providing several diffractive surfaces and a middle layer serving as a beamsplitter and servo-generating element for a light reflected from an optical storage medium. The middle layer is sandwiched by the diffractive lenses that are located on both outer parts of the DOE stack. The semiconductor substrate includes at least a laser source and several photodetectors. The middle layer serving its function preferably includes a polarization-selective DOE and a quarter-wave retarder oriented to rotate a polarization state of the laser source, so that only the light reflected from the optical storage medium is diffracted by the polarization-selective DOE.
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