Optical system for detecting surface defects and disk tester and disk testing method utilizing the same optical system
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United States of America Patent
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Issued Date -
Dec 5, 2002
app pub date -
May 23, 2002
filing date -
May 30, 2001
priority date (Note) -
Abandoned
status (Latency Note)
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Abstract
A defect detecting optical system includes a light receiving optical system including an objective lens provided above the surface of the disk in parallel to the surface for receiving the scattered light and focusing an image of a test region of the disk on the light sensor through the objective lens and a plurality (n) of light illuminating systems provided around the objective lens equiangularly in a plane parallel to the disk with an angular interval of substantially 360.degree./n and emitting light beams to the test region with elevation angles in a range from 55.degree. to 60.degree. measured from the surface of the disk, where n is an integer equal to or larger than 3.
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