Abstract-Terahertz pulse time-domain holography method for phase imaging of breast tissue

Nikolay S. Balbekin, Quentin Cassar,  Olga A. Smolyanskaya, Maksim S. Kulya,  Nikolay V. Petrov,  Gaetan MacGrogan,  Jean-Paul Guillet,  Patrick Mounaix,  Valery V. Tuchin, 

https://www.spiedigitallibrary.org/conference-proceedings-of-spie/10887/108870G/Terahertz-pulse-time-domain-holography-method-for-phase-imaging-of/10.1117/12.2508711.short?SSO=1

Pulse holographic imaging along with time-domain spectroscopy scan and tomographic techniques are of great interest. Since the advantages of holography are the lack of focusing optics and high spatial resolution, and, comparing with tomography, less computation cost for numerical reconstruction, this technique is preferable for the analysis of thin histological samples. In this work we have created the experimental scheme that involves measurement of diffraction pattern of the collimated THz pulse field spatial distribution at some distance behind the object in the time-domain mode, thus allowing reconstruction of amplitude and phase distribution at the object plane by numerical backpropagation of the wavefront in the spectral domain. In our experiment, we used a breast biopsy sample containing cancer tissues, we also performed numerical simulations accounting for experimental conditions to confirm the conceptual applicability of the reconstruction method.

Abstract-The Role of Scattering in Quasi-Ordered Structures for Terahertz Imaging: Local Order Can Increase an Image Quality

Irina N. Dolganova, Kirill I. Zaytsev,  Stanislav O. Yurchenko, Valeriy E. Karasik, Valery V. Tuchin

https://ieeexplore.ieee.org/document/8371640/

In this paper, we propose a computational approach for description of radiation transfer in a quasi-ordered medium and study the impact of scattering on electromagnetic wave propagation and image formation. It combines finite-difference time-domain method, Monte Carlo simulations, and radiative transfer theory. Using as an example terahertz imaging, we analyze modulation transfer function (MTF) of imaging system operated at 0.25 THz for scattering material layers placed between the object and the imaging plane. We experimentally study imaging of bar-pattern test-objects through a quasi-ordered scattering medium. Both numerical and experimental results are in good agreement and demonstrate an impact of quasi-ordered scatterers on quality of THz images, i.e. particular combination of the electromagnetic wavelength and parameters of scattering materials could enhance MTF compared with ones with random particle structures.