Sub-transducer element spatial resolution ultrasound wavefront modification using passive twin-layer compensators

Experimental comparisons between the active and passive approaches were conducted where the effective feature size of the intermediate medium was varied relative to the size of the transducer array elements. We show that if the feature size of the intermediate medium is larger than the size of the transducer elements that both the active and passive approach show equally good results. However, as the apparent feature size is decreased, the active method can no longer provide sufficient compensation while the passive method continues to compensate for the wavefront degradation.