Surface inspection tool
US5933230A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Apr 28, 1997 |
| Grant date | Aug 3, 1999 |
| Priority date | — |
| Expiry date | Apr 28, 2017 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N21/8806
- WIPO fieldMeasurement
- WIPO sectorInstruments
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.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.