Acceleration of Range Points Migration-Based Microwave Imaging for Nondestructive Testing

Abstract

A microwave ultrawideband radar offers advantages of high-range resolution and deep penetration depth in low-loss media, and is a promising efficient nondestructive testing technique. The traditional delay-and-sum (DAS)-based imaging algorithm inherently suffers from insufficient accuracy in determining the detailed structure of any buried foreign body. As a promising alternative, the range points migration (RPM)-based imaging method has been developed. However, this method faces a problem in terms of high computational cost, particularly in the case of three-dimensional objects, because it requires a densely sampled outer boundary to maintain its reconstruction accuracy. Therefore, this study accelerates the RPM-based method without sacrificing the reconstruction accuracy, exploiting the feature of Envelope-based outer boundary extraction. Finite-difference time-domain numerical simulation and experimental results indicate that our proposed method accurately reconstructs small air cavities buried in a concrete object with considerably low computational cost.