Measurement of Surface Displacement Excited by Emat Transducer

− The article discusses the measurement of surface displacement of an electrically conductive solid material. Deflection is excited by electro-magneto-acoustic transducer (hereinafter referred to as EMAT). Measurement is realized by laser interferometer. In our research the precise surface displacement measurement is necessary for two reasons. First is EMAT transducer numerical model convergence verification, second is the experimental optimization of EMAT transducer parameters such as sensitivity, frequency and direction characteristics. Used laser interferometer allows the accurate assessment of surface displacement in a relatively small item, which gives an advantage over using piezoelectric acoustic emission sensors that are limited by aperture effect at small wavelengths. In addition, laser interferometer is capable of surface displacement measuring directly under the EMAT device, which is very difficult with using other methods.