Method of and apparatus for detecting foreign substance
US4922308A · kind A · utility
34Cited by
5References
12Claims
0Family size
Assignee
Inventors
Key dates
| Filing date | Jun 29, 1987 |
| Grant date | May 1, 1990 |
| Priority date | — |
| Expiry date | Jun 29, 2007 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N2021/4792
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A method of and an apparatus for detecting a fine foreign substance in which the surface of a specimen is illuminated with linearly-polarized laser beam to detect light scattered from the surface and having passed through a polarization filter, the back side of the specimen is illuminated with light from a light source such as a mercury lamp to obtain the light and darkness information or phase information on the specimen surface by transmitted light from the specimen, and fine massive and filmy foreign substances on the specimen surface are detected on the basis of information given by the scattered light and transmitted light.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.