| 摘要 |
PROBLEM TO BE SOLVED: To provide an electromagnetic ultrasonic sensor which can generate with strong signal intensity an ultrasonic wave capable of corresponding to different incident angles at the same frequency.SOLUTION: An electromagnetic ultrasonic sensor 1 comprises a magnet 2 which has a magnetic pole on a surface facing an inspection object W of a ferromagnetic material and applies a magnetic field to the inspection object W and a coil body 3 which generates an electromagnetic acoustic wave in the inspection object W by generating an eddy current in the inspection object W to which the magnetic field is applied by the magnet 2. The coil body 3 has such a constitution that a plurality of coils 4a-4c are arranged in a direction vertical to the magnetization direction of the magnet 2, a current is sequentially applied from the coil 4a arranged on one end toward the coil 4c arranged on the other end of the plurality of coils 4, and the timing of applying the current to the adjacent coils is delayed by a prescribed time interval Δt.SELECTED DRAWING: Figure 3A |
