Fig. 4. Two-dimensional images of a linear defect under complex surfaces.
Optical images of experimental setups with the stretchable ultrasonic device tested on (A) planar, (B) concave, and (C) convex surfaces showing the good conformability of the device on these surfaces (first column); simulation results showing the different wave fields and sensing modes (second column); pulse-echo signals from the defects and boundaries with high SNR (third column); and acquired 2D images using DMAS algorithms with accurate and artifact-free positions (fourth column). S wave, shear wave; L wave, longitudinal wave; SNRD, SNR of pulse-echo response from the defect.