2013 年 37 巻 1 号 p. 1-7
We report the results we obtained from applying a magnetic system to detect cracks using a thin film magnetic field sensor to measure the hole of aluminum. The thin film magnetic field sensor consisted of a coplanar line and amorphous CoFeSiB film. The main characteristic of the sensor is that the phase of the carrier signal changes when a magnetic field is applied. The sensitivity of the developed sensor was 70 deg./Oe. We used the thin film magnetic field sensor in an experiment to measure leakage magnetic flux from the surface of the aluminum while applying an AC magnetic field to the aluminum. The surface of the aluminum was scanned by an electric stage with a motor. The phase value of the sensor was converted to a voltage value, and then measured with a lock-in amplifier. As a result, the hole of aluminum was detected by measuring the distribution of the leak magnetic flux on the aluminum surface.