Large-surface defect detection by single-frame spatial-carrier interferometry
US8275573B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Nov 23, 2009 |
| Grant date | Sep 25, 2012 |
| Priority date | — |
| Expiry date | Dec 31, 2030 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01B11/2441
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
An adaptive algorithm is tailored to fit the local fringe frequency of single-frame spatial-carrier data under analysis. Each set of data points used sequentially by the algorithm is first processed with a Fourier Transform to find the local frequency of the fringes being analyzed. That information is then used to adapt the algorithm to the correct phase step thus calculated, thereby optimizing the efficiency and precision with which the algorithm profiles the local surface area. As a result, defects are identified and measured with precision even when the slope of the surface varies locally to the point where the algorithm without adaptive modification would not be effective to measure them. Once so identified, the defects may be measured again locally with greater accuracy by conventional temporal PSI.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.