Open AccessVisualization of internal structure and internal stress in visibly opaque objects using full-field phase-shifting terahertz digital holography
Author(s) -
Masatomo Yamagiwa,
Takeo Minamikawa,
Fui Minamiji,
Tadahiko Mizuno,
Yu Tao,
Ryo Oe,
Hidenori Koresawa,
Yasuhiro Mizutani,
Tatsuya Iwata,
Hirotsugu Yamamoto,
Takeshi Yasui
Publication year - 2019
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.27.033854
Subject(s) - opacity , optics , terahertz radiation , holography , digital holography , visualization , image resolution , diffraction , phase (matter) , materials science , physics , computer science , artificial intelligence , quantum mechanics
We construct a full-field phase-shifting terahertz digital holography (PS-THz-DH) system by use of a THz quantum cascade laser and an uncooled, 2D micro-bolometer array. The PS-THz-DH enables us to separate the necessary diffraction-order image from unnecessary diffraction-order images without the need for spatial Fourier filtering, leading to suppress the decrease of spatial resolution. 3D shape of a visibly opaque object is visualized with a sub-millimeter lateral resolution and a sub-µm axial resolution. Also, the digital focusing of amplitude image enables the visualization of internal structure with the millimeter-order axial selectivity. Furthermore, the internal stress distribution of an externally compressed object is visualized from the phase image. The demonstrated results imply a possibility for non-destructive inspection of visibly opaque non-metal materials.