ULTRASOUND-STIMULATED VIBROACOUSTIC SPECTROGRAPHY

An ultrasound method based on radiation force is presented for imaging the acoustic response of a material to mechanical excitation, Acousti c energy was emitted from solids and tissues in response to an oscilla tory radiation force produced by interfering focused beams of ultrasou nd. Frequency spec tra of ultrasound-stimulated acoustic emission exhi bited object resonances. Raster-scanning the radiation force over the object and recording the amplitude and phase of the emitted sound resu lted in data from which images related to the elastic compositions of the acoustically emitting objects could be computed. Acoustic emission signals distinguished tuning-fork resonances, submillimeter glass sph eres, and calcification in excised arteries and detected object motion s on the order of nanometers.