| 摘要 |
Methods and instruments for suppressing multiple scattering noise and extraction of nonlinear scattering components with measurement or imaging of a region of an object with elastic waves, includes transmission of at least two elastic wave pulse complexes towards the region. The pulse complexes include a high frequency (HF) and a low frequency (LF) pulse. The HF pulse is so close to the LF pulse that it observes the modification of the object by the LF pulse at least for a part of the image depth. The frequency and/or amplitude and/or phase of said LF pulse relative to said HF pulse varies for each transmitted pulse complex to nonlinearly manipulate the object elasticity observed by the HF pulse along at least parts of its propagation, and received HF signals are picked up by transducers from at least one of scattered and transmitted components of the transmitted HF pulses. The received HF signals are processed to form measurement or image signals for display. In the process of forming said measurement or image signals, the received HF signals are delay corrected and/or pulse distortion corrected, and combined to form noise suppressed HF signals or nonlinear scattering HF signals.
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