Nonuniform Manual Scanning for Rapid Microwave Nondestructive Evaluation Imaging

Wideband synthetic aperture radar (SAR) technique is a robust imaging tool for microwave and millimeter-wave imaging such as nondestructive evaluation applications. In this paper, we present an alternative method to conventional raster scanning involving manually selected and nonuniformly distributed measurement positions, enabling the production of complete SAR images-potentially using only a fraction of the conventionally required measured data. The user is kept informed throughout the scanning process by a stream of real-time SAR images. Finally, data reconstruction algorithms are used offline to produce high-quality images with considerably lower background noise and image artifacts as compared to the real-time images. We also introduce a novel reconstruction method that uses the components of the SAR algorithm to advantageously exploit the inherent spatial information contained in the data, resulting in a superior data reconstruction and final SAR image. This paper presents the measurement methodology along with the images obtained from three different specimens of increasing geometrical complexity.