Surface inspection method
US4543602A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Apr 29, 1983 |
| Grant date | Sep 24, 1985 |
| Priority date | — |
| Expiry date | Apr 29, 2003 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N21/88
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
In a surface inspection method in which parallel rays passing through a thin slit are projected onto a surface of a specimen and a luminous line formed on the specimen surface by the parallel rays is viewed by a television camera so as to inspect the specimen surface, a photo-electric signal showing the luminous line is picked up from an output video signal of the television camera. The time from rising state of the horizontal synchronizing signal contained in the video signal to occurrence of a pulse of the photo-electric signal is measured in each period of the horizontal synchronizing signal. The time data in each period is compared with a previously set reference value, and whether or not the specimen passes the inspection is discriminated based on variation of the comparison result.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.