Detection of acoustically induced electromagnetic radiation

Electromagnetomechanical response of materials is detected through electromagnetic radiation induced by ultrasound waves. Target specimens are placed in the focusing zone of the ultrasound waves at a distance of ∼60mm from an acoustic generator. The radiation is picked up by a narrow-band loop antenna tuned to the ultrasound frequency. Due to the delay time caused by ultrasound wave propagation in the medium (water), the pulsed electromagnetic radiation from a target is well separated (temporally by ∼40μs) from the apparent signal attributed to the generator, allowing unambiguous and sensitive detection of true signals. Upon stimulation with ultrasounds, emission of electromagnetic radiation is found in bones, woods, plastics, and ferrites as well as a standard piezoelectric material (GaAs).