Eddy Current Probe for Surface and Sub-Surface Inspection

NASA's Langley Research Center has developed a novel probe for eddy current sensor applications that improves detection depth and measurement resolution. Although the use of anisotropic magnetoresistive (AMR) sensors in eddy current probes to improve sensitivity at low frequencies and increase the detection depth is known, the high-frequency sensitivity and small size of these sensors is less explored. This new probe incorporates two induction sources (i.e., one high-frequency and one low-frequency) and an AMR sensor; the result is improved resolution in near-surface material characterization, combined with simultaneous deep-flaw detection. Addition of a second high-frequency induction source, oriented to produce a magnetic field orthogonal to the first, allows for near-surface anomaly detection in two dimensions.