Deep Flaw Detection with Giant Magnetoresistive (gmr) Based Self-nulling Probe

The use of giant magnetoresistive (GMR) sensors for electromagnetic nondestructive evaluation has grown considerably in the last few years [1-4]. Technological advances in the research and development of giant magnetoresistive materials has led to commercially available GMR sensors with many qualities well suited for electromagnetic NDE. Low cost GMR magnetometers are now available which are highly sensitive to the magnitude of the external magnetic field, have a small package size, consume little power, and operate at room temperature [5]. Incorporation of these sensors into electromagnetic NDE probes has widened the application range of the field. In particular, the low frequency sensitivity of the devices provides a practical means to perform electromagnetic inspections on thick layered conducting structures.