Directional lighting and method to distinguish three dimensional information
US6901160B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Apr 26, 2001 |
| Grant date | May 31, 2005 |
| Priority date | — |
| Expiry date | Apr 10, 2023 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06T2207/30164
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
The present invention provides a method and an apparatus for evaluating the surfaces of substrates for three dimensional defects. The present invention uses low-angled lighting positioned on opposite sides of the substrate. A camera positioned above the substrate captures two images thereof, one using the first light source and one using the second. The first and second images are subtracted from one another to create a third image. Camera data suggestive of three dimensional features is emphasized by subtracting the two images and can be evaluated. A fourth image may be created by selecting the minimum values between the first and second images on a point-by-point basis. The fourth image also provides useful information in evaluating three dimensional defects.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.