Range Points Migration Based Spectroscopic Imaging Algorithm for Wide-Beam Terahertz Subsurface Sensor

Takamaru MATSUI  Shouhei KIDERA  

IEICE TRANSACTIONS on Electronics   Vol.E103-C   No.3   pp.127-130
Publication Date: 2020/03/01
Publicized: 2019/09/25
Online ISSN: 1745-1353
DOI: 10.1587/transele.2019ECS6005
Type of Manuscript: BRIEF PAPER
Category: Electromagnetic Theory
terahertz imaging,  subsurface imaging,  range points migration,  spectroscopic imaging,  synthetic aperture processing,  radar signal processing,  

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Here, we present a novel spectroscopic imaging method based on the boundary-extraction scheme for wide-beam terahertz (THz) three-dimensional imaging. Optical-lens-focusing systems for THz subsurface imaging generally require the depth of the object from the surface to be input beforehand to achieve the desired azimuth resolution. This limitation can be alleviated by incorporating a wide-beam THz transmitter into the synthetic aperture to automatically change the focusing depth in the post-signal processing. The range point migration (RPM) method has been demonstrated to have significant advantages in terms of imaging accuracy over the synthetic-aperture method. Moreover, in the RPM scheme, spectroscopic information can be easily associated with each scattering center. Thus, we propose an RPM-based terahertz spectroscopic imaging method. The finite-difference time-domain-based numerical analysis shows that the proposed algorithm provides accurate target boundary imaging associated with each frequency-dependent characteristic.