Magnetic domain imaging in coated silicon-iron using magnetoresistive sensors

This paper presents the application of permalloy magneto-resistive sensors for non destructive magnetic domain imaging of coated Si-Fe sheets. The principles of measurement, arrangement of the sensor, operating conditions and examples of the application results are described. The presented method is based on the measurement of stray fields above the sheet surface. The domain images mapped by computer from field measurements, agree well with those obtained using a commercial domain viewer. The advantage of the presented MR based system is its suitability for automated product inspection.