Foreign substance inspecting apparatus
US4468120A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jan 28, 1982 |
| Grant date | Aug 28, 1984 |
| Priority date | — |
| Expiry date | Jan 28, 2002 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N21/94
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
An apparatus for detecting the presence of a foreign substance adhering to a planar substrate comprises irradiating means capable of emitting a light beam incident on one surface of the substrate obliquely relative to the surface, means for displacing the irradiating means and the substrate relative to each other so that the position of incidence of the light beam onto the substrate is scanned on said one surface, metering means capable of receiving a plurality of irregular reflected light beams of the light beam which have been irregularly reflected on said surface toward different directions and producing a plurality of electrical outputs corresponding to the intensity of light of the plurality of irregular reflected light beams, and means for deciding the presence of the foreign substance on the basis of the plurality of electrical outputs.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.