FMR Probe method utilizing main and spurious resonance modes for detecting surface flaws
US4364012A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Mar 3, 1980 |
| Grant date | Dec 14, 1982 |
| Priority date | — |
| Expiry date | Mar 3, 2000 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N22/02
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
In ferromagnetic resonance (FMR) probe apparatus for detecting surface flaws in a metal surface, probe impedance changes resulting from flaws are distinguished from impedance changes resulting from probe lift-off from the metal surface. A constant magnitude dc magnetic field and a constant frequency and constant magnitude rf magnetic field are applied to the ferromagnetic crystal and the real and imaginary components of probe impedance are detected. The impedance changes due to flaws are at least partially orthogonal to the impedance changes due to lift-out, and by observing probe impedance on an oscilloscope the presence of a flow or the occurrence of lift-off are readily identified.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.