Optical inspection system and method for detecting flaws on a diffractive surface
US5625193A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jul 10, 1995 |
| Grant date | Apr 29, 1997 |
| Priority date | — |
| Expiry date | Jul 10, 2015 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N21/9501
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
An improved optical inspection system for detecting flaws on a diffractive surface containing surface patterns includes: an ultraviolet illumination means for illuminating a region on the diffractive surface to generate a scattered intensity distribution in response to either a flaw or a surface pattern; means for detecting the intensity level of the scattered intensity distribution at a plurality of locations about the diffractive surface; means for establishing a minimum detected intensity level; means, responsive to the minimum detected intensity level, for indicating the absence of a flaw on the illuminated region of the diffractive surface when the minimum detected intensity level is below a threshold intensity level and for indicating the presence of a flaw on the illuminated region of the diffractive surface when the minimum detected intensity level exceeds the threshold intensity level; and means for moving the diffractive surface to generate a scan pattern on the diffractive surface to inspect the entire surface.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.