Full-matrix capture with phased shift migration for flaw detection in layered objects with complex geometry

This paper introduces a method for an ultrasonic imaging with a phased array based on a wave migration algorithm. The method allows for imaging layered objects with lateral velocity variations such as objects with a complex geometry or layers that are not perpendicular to the array's axis. The full-matrix capture ensures that there is enough information to reconstruct an image even when the wave indication angle is large. The method is implemented in a omega-k domain. The proposed algorithm is first tested in a single simulation of a concave object with side drilled holes under the concave surface. For evaluating the algorithm's performance three experiments are presented: one with a tilted object (surface not perpendicular with respect to the array axis) with side drilled holes and two experiments of an object with concave surface and two artificial defects under it. The results presented in the paper verify that the proposed method reconstructs images from the data gathered with the phased array.