Automatic lift-off compensation for pulsed eddy current inspection
US8008913B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Jun 6, 2008 |
| Grant date | Aug 30, 2011 |
| Priority date | — |
| Expiry date | Nov 20, 2029 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N27/9053
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
Variations in the lift-off separation between a probe and the surface of a structure to be tested often mask the detection of defects in the structure. A method and apparatus for automatically classifying and compensating for variations in the lift-off is described. A reference signal at a known lift-off may be weighted by a corresponding calculated ratio parameter and subtracted from a test signal to compensate for lift-off. A number of reference signals are preferably obtained and the largest magnitude gradient for each reference signal is preferably determined. The largest magnitude gradient for subsequent test signals is also obtained and the corresponding reference signal with the closest largest magnitude gradient to the test signal is identified and the corresponding reference signal is selected in the related compensation procedure. Such a method has been found to restore the signal such that lift-off is removed and defects are easily identified.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.