Delaminations, cracks and other defects in engineered structures often lie close to the
theoretical resolution limit for ultrasonic waves. While ultrasonic waveform tomography has
succeeded in detecting such features, recovery is difficult because it requires
computationally expensive high-frequency numerical wave simulations and an accurate
understanding of large-scale background variations of the engineered structure. Without
such knowledge, small defects may be incorrectly imaged or go undetected altogether. To …