Abstract

Terahertz (THz) radiation has shown enormous potential for non-destructive inspection in many contexts. Here, we present a method for imaging defects in chocolate bars that can be extended to many other materials. Our method requires only a continuous wave (CW) monochromatic source and detector at relatively low frequencies (280 GHz) corresponding to a relatively long wavelength of 1.1 mm. These components are used to construct a common-path configuration enabling the capturing of several images of THz radiation diffracted by the test object at different axial depths. The captured diffraction-rich images are used to constrain the associated phase retrieval problem enabling full access to the wave field, i.e., real amplitude and phase distributions. This allows full-field diffraction-limited phase-contrast imaging. Thus, we experimentally demonstrate the possibility of identifying contaminant particles with dimensions comparable to the wavelength.

© 2022 Optica Publishing Group

Nonlinear primal–dual algorithm for the phase and absorption retrieval from a single phase contrast image

Kannara Mom, Max Langer, and Bruno Sixou
Opt. Lett. 47(20) 5389-5392 (2022)

Enhanced multiple-plane phase retrieval using adaptive support

Christian Ray L. Buco and Percival F. Almoro
Opt. Lett. 44(24) 6045-6048 (2019)

Enhanced intensity variation for multiple-plane phase retrieval using a spatial light modulator as a convenient tunable diffuser

Percival F. Almoro, Quang Duc Pham, David Ignacio Serrano-Garcia, Satoshi Hasegawa, Yoshio Hayasaki, Mitsuo Takeda, and Toyohiko Yatagai
Opt. Lett. 41(10) 2161-2164 (2016)

Terahertz phase retrieval imaging in reflection

Nikolay V. Petrov, Jean-Baptiste Perraud, Adrien Chopard, Jean-Paul Guillet, Olga A. Smolyanskaya, and Patrick Mounaix
Opt. Lett. 45(15) 4168-4171 (2020)

Phase contrast-based phase retrieval: a bridge between qualitative phase contrast and quantitative phase imaging by phase retrieval algorithms

Nathaniel Hai and Joseph Rosen
Opt. Lett. 45(20) 5812-5815 (2020)