Detecting irregularities in a coating on a substrate
US4469442A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jan 11, 1982 |
| Grant date | Sep 4, 1984 |
| Priority date | — |
| Expiry date | Jan 11, 2002 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N2201/1045
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
Irregularities in a coating on a substrate in which the coating includes optical scattering centers can be detected by irradiating the coating with polarized light and examining light from the coating through a filter which removes light having the same polarization as the initial beam. Light scattered by the optical scattering centers is transmitted through the filter, while specularly reflected light from the top surface of the coating, from the substrate exposed by gaps in the coating, or reflected by alien material on the coating is filtered out. As a result irregularities can be detected as intensity minima of the transmitted radiation.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.