| 摘要 |
PURPOSE:To generate an SH wave in a body to be inspected through the mutual operation between an eddy current and a magnetic field by producing the magnetic field crossing the surface of the body to be inspected by an electromagnet at the upper part of the body to be inspected and supplying an AC current to a coil facing the body to be inspected. CONSTITUTION:Magnetic poles 2c and 2b of the electromagnet 2 are set opposite the top surface and flank of the body to be inspected 10 and the coil 3 is arranged between the magnetic pole 2c and body to be inspected 10. The coil 3 is made of a conductor 3b provided woven through long holes 3a of a coil base 31 in the thickness direction, and a high-frequency current is supplied intermittently to the conductor, so that currents flow in the opposite directions at intervals of the pitch of the long holes 3a. For the purpose, the base is put in a DC magnetic field and then a force is generated in parallel to the surface of the sample in opposite directions at intervals of the pitch. This force is inverted in direction in synchronism with the applied AC current to generate the SH wave which is propagated slantingly downward in the body to be inspected 10. |
