Acceleration of RPM-based microwave imaging for non-destructive testing

A microwave ultra-wideband (UWB) radar has an advantage for high range resolution and deep penetration depth in a concrete object, and is promising for non-destructive testing for aging transportation infrastructure. The traditional delay-and-sum (DAS) based imaging algorithm inherently suffers from an insufficient resolution to identify a detailed structure of buried targets. As promising alternative, the range points migration (RPM)-based imaging method has been developed. However, this method faces a serious problem in terms of an expensive computational cost, particular in three-dimensional case. This paper, then, introduces an acceleration of the RPM-based imaging method by exploiting the feature of Envelope outer boundary extraction. The results from experimental data demonstrate that this method accurately reconstructs the shape of air cavity buried in concrete object with considerably reduced computational cost.