INHOMOGENEITY DETECTION SYSTEM

摘要

The system which is the subject of this patent utilizes an array of SQUID detectors to map the magnetic field associated with test currents flowing in the component to be tested. The SQUID (acronym for Superconducting Quantum Interference Device) 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. In the preferred embodiment, multi-dimensional test currents are injected into the component being tested; the injection being made between specific electrodes (of a matrix of 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 within the body under study As the frequency increases, "skin effect" decreases the depth of the test current permitting multi-dimensional profiles of the defect to be imaged. Computer data processing permits high resolution images of inhomogeneities to be produced that are not attainable by any other means.