Advanced THz MIMO Sparse Imaging Scheme Using Multipass Synthetic Aperture Focusing and Low-Rank Matrix Completion Techniques

Abstract

This paper proposes an advanced THz multipleinput-multiple-output (MIMO) near-field sparse imaging scheme for target detection that uses single-pass synthetic aperture focusing and multi-pass interferometric synthetic aperture focusing techniques to improve imaging effectiveness and efficiency. It benefits from the MIMO of linear sparse periodic array (SPA) and random sparse imaging to reduce sampling data as well as system cost. Both simulated and proof-of-concept experimental results have verified the scheme, revealing that the single-pass synthetic aperture imaging approach is sufficient to identify pure metallic targets with 3.87% of λ/2 sampling data. And multi-pass interferometric synthetic aperture imaging approach is capable of improving image quality on image signal to noise ratio and contrast, which is ideal for detecting more challenging targets. The random sparse imaging with help of low rank matrix completion (LRMC) technique has shown promising potential of achieving equivalent image quality when further reducing 43.75% data in the experiment of 5-pass imaging on a complex target, this corresponds to 82.51% data reduction compared to λ/2 sampling.

FFT-based 220 GHz Sparse Imaging for Target Detection

“…Compared to Fig. 2, image quality is obviously improved so it is competent to detect more challenging targets [7]. Due to larger volume of data used, the reconstruction time increases to 0.83 s and 0.17 s with FFT/IFFT and FFT matched filtering reconstruction approach, respectively.…”

“…Due to larger volume of data used, the reconstruction time increases to 0.83 s and 0.17 s with FFT/IFFT and FFT matched filtering reconstruction approach, respectively. Finally, sparse imaging is studied by randomly turning off some elements in SPA, which provides a solution to save system cost [7]. The reconstructions with FFT/IFFT approach of 2 Tx's & 2 Rx's off and 1 Tx & 1 Rx off are shown in Fig.…”

“…1(c). The peak gain of horn is about 23.81 dB at 220 GHz and the typical input power to the horn at 220 GHz is -13 dBm (0.05 mW) [7]. The photo of whole experimental imaging system is shown in Fig.…”

“…Thereafter, multistatic-to-monostatic conversion is applied to gain a FFT compatible data so FFT-based image reconstruction approaches can be applied [3], [8]. Different from FFT/IFFT and FFT matched filtering in [3], internal zero padding, multi-pass synthetic aperture focusing, and sparse imaging are proposed and investigated in this work [7].…”

Integrated sensing and communication in 6G: a prototype of high resolution multichannel THz sensing on portable device

“…The THz penetration characteristic was studied in tumor identification [5], which was able to distinguish between normal and tumor tissues without additional damage as X-rays do. Beside the medical appllication, nondestructive detection of THz is also promising in quality control and secuirty scanning [6,7], With technologies such as virtual aperture and sparse sampling, it is possible to image a distant object with millimeter accurcy.…”