Manipulating curvature of plane wavefront using holey plates
TL;DR: In this paper, a metamaterial device made of Gradient Refractive Index Phononic Crystals is proposed to transform curvature of a wavefront generated from a single element transducer.
Abstract: Ultrasonic inspection is commonly used for Non-Destructive Evaluation (NDE). Phased array ultrasonic transducers (PAUT) enable beamforming and beam steering by implementing electronic time delays. By providing appropriate delays in exciting individual elements, PAUTs can generate a curved wavefront. The authors propose a metamaterial device made of Gradient Refractive Index Phononic Crystals to transform curvature of a wavefront generated from a single element transducer. The manipulation of the wavefront as it passes through holey region, is simulated using the finite element method. Results from experimental studies carried out on a holey plate, designed using this approach are comparable to simulation results. The authors suggest that add-on devices can be designed using this approach for tailoring wave incidence in ultrasonic inspection.