Eddy current imaging apparatus and method using phase difference detection
US5006800A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Nov 6, 1989 |
| Grant date | Apr 9, 1991 |
| Priority date | — |
| Expiry date | Nov 6, 2009 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N27/82
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A phase-difference eddy current imaging system has a bridge circuit including a pair of coils with one or both coils disposed proximate an object that may contain one or more flaws. An oscillator is coupled to the bridge circuit and also to a pair of phase detectors that are coupled to the coils. A differential amplifier is coupled to the phase detectors for providing a comparison signal. A method for eddy current imaging using phase difference detection comprises providing relative movement between an object and at least one of a pair of coils, measuring the phase of the effective reactance in each of the coils, comparing the measured values, and formatting the compared values as a function of spatial position.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.