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.

Abstract-A hybrid continuous-wave terahertz imaging system

Irina N. Dolganova^1,a), Kirill I. Zaytsev^1,b), Anna A. Metelkina¹,Valeriy E. Karasik¹ and Stanislav O. Yurchenko^1,c)
http://scitation.aip.org/content/aip/journal/rsi/86/11/10.1063/1.4935495
1 Bauman Moscow State Technical University, 2nd Baumanskaya str. 5, Moscow 105005, Russia
a) Electronic mail: in.dolganova@gmail.com
b) Electronic mail: kirzay@gmail.ru
c) Electronic mail: st.yurchenko@mail.ru
Rev. Sci. Instrum. 86, 113704 (2015); http://dx.doi.org/10.1063/1.4935495

A hybrid (active-passive mode) terahertz (THz) imagingsystem and an algorithm for imagingsynthesis are proposed to enhance the THz image quality. The concept of imagecontrast is used to compare active and passive THz imaging. Combining the measurement of the self-emitted radiation of the object with the back-scattered source radiation measurement, it becomes possible to use the THz image to retrieve maximum information about the object. The experimental results confirm the advantages of hybrid THz imagingsystems, which can be generalized for a wide range of applications in the material sciences, chemical physics, bio-systems, etc.

Abstract-Scattering of terahertz radiation in thin layers of dielectric materials

Irina N. Fokina ; Kirill I. Zaytsev ; Valeriy E. Karasik ; Konstantin P. Tsapenko

[-] Author Affiliations

Irina N. Fokina, Kirill I. Zaytsev, Valeriy E. Karasik, Konstantin P. Tsapenko

Bauman Moscow State Technical Univ. (Russian Federation)

http://proceedings.spiedigitallibrary.org/proceeding.aspx?articleid=1743239

Scattering of THz radiation in inhomogeneous media is an important reason of reducing spectral information in received THz signal for different applications. Scattering of THz radiation in thin layers of dielectric material was studied, particularly, in fabric materials. A structure of different types of cloth fabric was studied, and mathematical model of fabric was suggested, which is a system of dielectric cylinders. Scattering of THz radiation was modeled numerically. Scattering cross-section and indicatrix were calculated, and then spectral transmittance was computed. During a set of experiments THz spectral transmittance of various fabric materials were obtained and numerical results were approved. The developed method for receiving scattering characteristics of different materials can be used for extracting useful information from received THz signal. © (2013) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.