TIME-VARYING NONLINEAR DIFFRACTION TOMOGRAPHY-A NEW FORM OF ACOUSTICAL IMAGING

摘要

The present harmonic imaging commercialised in the market is based on the nonlinear distortion of finite-amplitude ultrasonic waves when traveling through real media and this manifests itself in the frequency domain as the appearance of additional harmonic signals at integer multiples of the original frequency. Our paper deals with the interaction of two sound waves in solids or human tissues giving rise to a third sound wave formed which is a second harmonic of original frequency. This can lead to the determination of the third order elastic (TOE) constants of the human tissues and shows the possibility of a new form of elasticity imaging.