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.

中文翻译：

---

基于多层宽带频率干涉技术的太赫兹MIMO线性阵列空间目标三维表面重建

在本文中，使用太赫兹波段的多输入多输出 (MIMO) 线性阵列研究了空间目标的三维 (3-D) 表面重建技术。传统的基于波数域积分的重建算法由于距离方向的步长固定，无法准确地重建连续曲面。为了克服这一缺点，提出了一种无相位解缠多层宽带频率干涉算法（MWFIA）。MWFIA根据干涉相位图像带宽对应的距离分辨率将目标划分为若干层，可以实现任意变化距离范围的目标的表面重建。此外，为了确保在低信噪比环境下获得令人满意的重建精度，通过在相邻中心频点的宽带二维成像结果之间进行干涉相位提取，极大地抑制了噪声引入的干涉相位误差。提供了 0.22 THz 波段的模拟和实验结果，以证明与基于波数域积分和先前基于频率干涉测量的表面重建技术相比，所提出方法的性能。