Method of inspecting microscopic surface defects
US4449818A · kind A · utility
90Cited by
0References
8Claims
0Family size
Assignee
Inventors
Key dates
| Filing date | Feb 9, 1982 |
| Grant date | May 22, 1984 |
| Priority date | — |
| Expiry date | Feb 9, 2002 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N21/88
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A method is provided for inspecting defects in the surface of an object to be inspected, wherein oblique lighting and perpendicular lighting are alternately applied to a location where a defect or a foreign substance possibly exists. Brightness detected in the location under the application of oblique lighting is evaluated as a foreign substance so as to be discriminated from a defect. Defects are classified through shape recognition of a defect pattern obtained under the application of perpendicular lighting.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.