Optical defect inspection apparatus
US7894052B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Feb 12, 2010 |
| Grant date | Feb 22, 2011 |
| Priority date | — |
| Expiry date | Feb 12, 2030 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N2021/95676
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A laser beam oscillated from a laser source is folded in its path by first and second plane mirrors and enters a beam expander. The surface of each plane mirror is deteriorated with illumination by the laser beam and the reflectance is reduced. To avoid a light quantity of the laser beam entering the beam expander from being reduced below a reference value, when the laser beam is illuminated over a certain time, a position on each of the first and second plane mirrors at which the laser beam is illuminated is changed by a structure for rotating and/or translating a reflecting surface of each plane mirror on a plane, which includes the plane mirror, while an optical axis is kept same. Thus, the useful life of each plane mirror can be prolonged without displacing the optical axis.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.