Surface inspection method and surface inspection apparatus
US7761246B2 · kind B2 · utility
Assignee
Inventor
Key dates
| Filing date | Jan 6, 2009 |
| Grant date | Jul 20, 2010 |
| Priority date | — |
| Expiry date | Jan 6, 2029 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N21/47
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
When detecting light scattered by an object to be inspected by using a pulse laser as a light source, noise increases unless a sampling repletion period of an A/D converter is determined so as to be related to a pulse oscillation repetition period of the light source. (1) The sampling repletion period of the A/D converter is set equal to the pulse oscillation repetition period of the light source or an integer times thereof, and the sampling is synchronized with oscillation of the light source. Or (2) the sampling repletion period of the A/D converter is set equal to a half-integer times the pulse oscillation repetition period of the light source. Even if a ripple component resulting from emission pulses of the light source remains in the scattered light signal supplied to the A/D converter remains, therefore, its influence can be eliminated or reduced.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.