Three-Dimensional Terahertz Coded-Aperture Imaging Based on Geometric Measures

Abstract

For synthetic aperture radars, it is difficult to achieve forward-looking and staring imaging with high resolution. Fortunately, terahertz coded-aperture imaging (TCAI), an advanced radar imaging technology, can solve this problem by producing various irradiation patterns with coded apertures. However, three-dimensional (3D) TCAI has two problems, including a heavy computational burden caused by a large-scale reference signal matrix, and poor resolving ability at low signal-to-noise ratios (SNRs). This paper proposes a 3D imaging method based on geometric measures (GMs), which can reduce the computational burden and achieve high-resolution imaging for low SNR targets. At extremely low SNRs, it is difficult to detect the range cells containing scattering information with an ordinary range profile. However, this difficulty can be overcome through GMs, which can enhance the useful signal and restrain the noise. By extracting useful data from the range profile, target information in different imaging cells can be simultaneously reconstructed. Thus, the computational complexity is distinctly reduced when the 3D image is obtained by combining reconstructed 2D imaging results. Based on the conventional TCAI (C-TCAI) model, we deduce and build a GM-based TCAI (GM-TCAI) model. Compared with C-TCAI, the experimental results demonstrate that GM-TCAI achieves a more impressive performance with regards to imaging ability and efficiency. Furthermore, GM-TCAI can be widely applied in close-range imaging fields, for instance, medical diagnosis, nondestructive detection, security screening, etc.

Three-Dimensional Terahertz Coded-Aperture Imaging Based on Back Projection

“…Therefore, GM-TCAI proposed in Ref. [ 18 ] adopts GM to find the range cells containing scattering information. Both Refs.…”

“…Therefore, Ref. [ 18 ] tries to get the right positions of the spike pulses by learning the intrinsic nature of the range profile with geometric measures (GM) [ 19 , 20 ]. Ref.…”

“…Ref. [ 18 ] attempts to introduce the GM or the information geometry into radar imaging area. Until now, TCAI has two kinds of imaging methods: time-domain TCAI, range-domain TCAI.…”

“…[ 16 ] and traditional TCAIs are time-domain TCAIs while Refs. [ 17 , 18 ] belong to range-domain TCAI.…”

Semantic Fusion and Joint Analysis of Terahertz and 3d Video Images by the Means of Object-Oriented Logic Programming

“…Active terahertz video surveillance is historically associated with such areas as radar and holography [39,41]. At present, in the field of active terahertz observation, it has been proposed to use the mechanical and digital beam formation [20,42,43], terahertz holography [44,45], time-of-flight terahertz tomography [46], synthesized apertures [47] to obtain information on the threedimensional surface of the object under study -49], coding apertures [50][51][52][53][54], frequency modulation of the signal [55], antennas from metamaterials [56], etc.…”