Method and apparatus for magnetic detection of flaws
US4982158A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jun 23, 1988 |
| Grant date | Jan 1, 1991 |
| Priority date | — |
| Expiry date | Jun 23, 2008 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01R33/10
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
An array of SQUID detectors to map the magnetic field associated with test currents flowing in the component to be tested. The SQUID is an ultrasensitive, miniature device that transduces a faint magnetic field to a measurable voltage. Perturbation occurs in the test currents and the associated magnetic field at physical defects or inhomogeneities. Multi-dimensional test currents are injected into the component being tested; the injection being made between specific electrodes by varying the direction of the current until it is normal to the direction of the defect to maximize and amplify the effect of the perturbation. The perturbation is detected by the SQUID grid which pinpoints the location, orientation, and size of the defect. The frequency of the injected current can be made to sweep the spectrum from DC to the highest response limit of the SQUID to scan for defects at various depths. As the frequency increases, "skin effect" decreases the depth of the test current permitting multi-dimensional profiles of the defect to be imaged. Computer processing permits high resolution images of inhomogeneities to be produced.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.