Patent ID: 6400146
Filing Date: 2002-06-04
Classification: G01N

Abstract:
A sensor head for detecting variations in a magnetic field induced on the surface of a test piece by an electromagnetic elongated yoke, the sensor head comprisinga reference coil for sensing magnetic fields produced by the current, the reference coil having a longitudinal axis parallel to a longitudinal axis of the elongated yoke, and the reference coil being disposed between the yoke and the test piece; a plurality of sensor coils for sensing variations in magnetic fields, each sensor coil having a longitudinal axis which intersects the longitudinal axis of the reference coil; each sensor coil being positioned between the reference coil and the yoke; and mounting means for mounting the reference coil and the plurality of sensor coils in the sensor head wherein at least one of the plurality of sensor coils has a longitudinal axis not perpendicular to the longitudinal axis of the reference coil.