Optics: measuring and testing – Inspection of flaws or impurities – Surface condition
Patent
1997-04-28
1999-08-03
Pham, Hoa Q.
Optics: measuring and testing
Inspection of flaws or impurities
Surface condition
3562431, 359205, 359216, G01N 2100
Patent
active
059332301
ABSTRACT:
A laser based inspection tool (LIT) for inspecting planar surfaces is described. In a preferred embodiment the LIT can simultaneously inspect both planar surfaces of disks for use in disk drives. The choice of a polygon scanner is preferred, but other scanning means such as a galvonometer mirror could be used. A separate polygon scanner is used for each side of the disk. The polygons are arranged in a common plane, but rotate in opposite directions to reduce the inteference which might otherwise result when the beams pass through the central hole in the disk and impinge on the detection channel for the other side. Preferably the rotation of the polygons is synchonized and angularly offset so that the two beams are synchonized and offset. The rotating polygons may conveniently be included in a system which scans each of the two laser beams through a telecentric lens assembly onto the surface and which routes the reflected light which passes back through the telecentric lens and is reflected from the polygons to the detection component.
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Imaino Wayne Isami
Juliana, Jr. Anthony
Latta Milton Russell
Lee Charles H.
Leung Wai Cheung
International Business Machines - Corporation
Knight G. Marlin
Pham Hoa Q.
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