Nondestructive testing by differential type of rotational magnetic sensor

It is very difficult to estimate a depth, position and shape of a minor reverse side defect because a signal derived from it is very small and noisy. Therefore, we are improving an electromagnetic non-destructive testing (NDT) system such as a rotational magnetic flux sensor and a differential type of eddy current probe to estimate it. We combined two types of the magnetic sensor into a differential type of a rotational magnetic flux sensor. This new magnetic sensor can obtain some effective information for the depth, position and shape of a reverse side defect on a metallic material plate. The experimental results show the validity of this new magnetic sensor.