Terahertz 3-D Imaging for Non-Cooperative On-the-Move Whole Body by Scanning MIMO-Array-Based Gaussian Fan-Beam

Abstract

This work proposes a novel terahertz (THz) 3-D imaging system that combines the Gaussian-fan-beam scanning and multiple-input–multiple-output (MIMO) array to create a high frame rate, large field of view (FoV), and high-resolution radar images for continuously noncooperative on-the-move personnel security screening. The main novelty of the present system is that the 3-D THz focused images of the noncooperative on-the-move whole body can be created in real time when the persons are illuminated by scanning the MIMO-array-based Gaussian fan beam. In this article, the 3-D image is composed of a serial of 2-D slice images that are reconstructed by the proposed MIMO-array-based phase shift migration algorithm under the illumination of the THz Gaussian fan beam. Meanwhile, an analytical expression of the reconstructed point-spread function is derived to provide the theoretical spatial resolutions quantitatively. One prototype imager was designed for the proof-of-principle experiments in the 0.2 THz band, and the image reconstruction process is implemented in real time by the proposed hybrid central processing unit (CPU)–graphics processing unit (GPU) solution. At this stage, an FoV of 500 cm <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times200$ </tex-math></inline-formula> cm at a 10 m distance costs less than 0.1 s for 3-D imaging during 10 Hz mechanical Gaussian-fan-beam scanning. Finally, both simulation and experimental results validate the effectiveness of the proposed imaging algorithm on image reconstruction quality, including resolution, frame rate, and FoV.