Three-Dimensional Surface Reconstruction of Space Targets Using a Terahertz MIMO Linear Array Based on Multilayer Wideband Frequency Interferometry Techniques

In this article, the three-dimensional (3-D) surface reconstruction techniques of space targets were studied with a multiple-input-multiple-output (MIMO) linear array in the terahertz band. Conventional wavenumber domain integration-based reconstruction algorithm is unable to accurately reconstruct the continuous surfaces owing to the fixed step length in the range direction. To overcome this shortcoming, a phase unwrapping-free multilayer wideband frequency interferometry algorithm (MWFIA) was proposed. The MWFIA divides the targets into several layers based on the range resolution corresponding to the bandwidth of interference phase images, which can achieve surface reconstruction of targets with arbitrary varying range of distance. Besides, to ensure a satisfactory reconstruction accuracy under low signal-to-noise ratio environments, the interference phase errors introduced by noise are greatly suppressed by performing interference phase extraction between wideband two-dimensional imaging results of adjacent center frequency points. Both simulation and experimental results in the 0.22 THz band were provided to demonstrate the performance of the proposed method in comparison with those of the wavenumber domain integration-based and the previous frequency interferometry-based surface reconstruction techniques.