US Patent 7726193 Electromagnetic acoustic transducer with cross-talk elimination

The electromagnetic acoustic transducer (EMAT) transducer disclosed herein is useful for the non-destructive analysis of objects. The transducer comprises a core having a winding and a coil disposed between the core and the object to be analyzed. One transducer can be used as a transmitter and another transducer as a receiver. Then selectively switching static magnetic field in either transmitter or receiver and processing data with and without static magnetic field allows for eliminating artifacts due to parasitic coupling between the transmitter/receiver pair. The switching of the static magnetic field can be implemented either by using electromagnet or a pair of permanent magnets where magnetization of one permanent magnet is reversed to provide cancellation of the static magnetic field.