University of Oulu

V. A. Mikhnev, S. N. Vainshtein and J. T. Kostamovaara, "Time-Domain Terahertz Imaging of Layered Dielectric Structures With Interferometry-Enhanced Sensitivity," in IEEE Transactions on Terahertz Science and Technology, vol. 10, no. 5, pp. 531-539, Sept. 2020, doi: 10.1109/TTHZ.2020.3003500

Time-domain terahertz imaging of layered dielectric structures with interferometry-enhanced sensitivity

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Author: Mikhnev, Valeri A.1; Vainshtein, Sergey N.1; Kostamovaara, Juha T.1
Organizations: 1Faculty of Information Technology and Electrical Engineering, Oulu University, FIN-90014 Oulu, Finland
Format: article
Version: accepted version
Access: open
Online Access: PDF Full Text (PDF, 3.1 MB)
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Language: English
Published: Institute of Electrical and Electronics Engineers, 2020
Publish Date: 2020-11-18


This article presents a time-domain imaging technique for layered dielectric slabs using a solid-state wavelet generator with subterahertz carrier frequency. The technique utilizes the dual nature of a wavelet, i.e., both the applicability of time-of-flight measurements and the ability of wavelets to interfere in thin dielectric layers at a carrier frequency that is preserved in spite of the ultrawideband character of the signal. This results in a very high sensitivity of the time delay of the resultant pulse to variations in the effective thickness (thickness × refractive index) of the dielectric layer. It is shown using a plane-wave analysis of the pulse propagation that under certain conditions, this sensitivity enhancement can reach an order of magnitude. The experimental setup for the reflection-mode operation is described and its performance in the discrimination of healthy and malignant tissues and in the detection of corrosion under paint is demonstrated.

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Series: IEEE transactions on terahertz science and technology
ISSN: 2156-342X
ISSN-E: 2156-3446
ISSN-L: 2156-342X
Volume: 10
Issue: 5
Pages: 531 - 539
DOI: 10.1109/TTHZ.2020.3003500
Type of Publication: A1 Journal article – refereed
Field of Science: 213 Electronic, automation and communications engineering, electronics
Funding: The authors would like to thank Dr. J. Näpänkangas and Dr. R.Blanco-Sequeiros of Oulu University Hospital for providing ex vivo tissue samples for the THz measurements. Permission for the use of the breast cancer tissue samples (reg. no. 59-2009) was obtained from the Ethical Board of Oulu University Hospital, Finland.
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