Surface inspection of a disk by diffraction pattern sampling
US5781649A · kind A · utility
26Cited by
12References
10Claims
0Family size
Assignee
Inventor
Key dates
| Filing date | Apr 15, 1996 |
| Grant date | Jul 14, 1998 |
| Priority date | — |
| Expiry date | Apr 15, 2016 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N21/94
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
An optical inspection apparatus detects anomalies by reflecting a beam of coherent light off the surface of a sample. An anomaly present on the surface causes the reflected beam to be diffracted at an angle which corresponds to a scale of the anomaly. An optical detection array is positioned to receive the reflected diffraction pattern and produce an electrical signal which corresponds to the diffraction angle of the reflected pattern. The electrical signal may then be processed to determine the location and scale of the anomaly from the detected diffraction angle.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.