High-Order Pulse-Echo Ultrasound

Multiple reflections between transducer and imaged object can naturally occur in ultrasound imaging and other acoustic sensing applications such as sonar. The repeated interaction of the emitted wave front with the imaged object is traditionally regarded as an undesired reverberation artifact, often misinterpreted as fictitious acoustic boundaries. We introduce high-order reflection pulse-echo (HOPE) ultrasound, a method that leverages high-order reflections to improve on several aspects of conventional ultrasound imaging. HOPE is experimentally demonstrated to resolve submicrometer features by breaking through the sampling limit. The major contrast enhancement of the high reflection orders allowed defects within materials invisible to conventional scanning acoustic microscopy to be revealed. The technique is further shown to improve accuracy of frequency-dependent ultrasound attenuation measurements from biological tissues. HOPE ultrasound requires no additional hardware and is easy to implement, underscoring its potential to boost imaging performance in biomedical imaging, nondestructive testing, and other acoustic sensing applications.