Time-Domain Terahertz Imaging of Layered Dielectric Structures with Interferometry-Enhanced Sensitivity

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.

Authors:
Mikhnev Valeri A., Vainshtein Sergey N., Kostamovaara Juha T.

Publication type:
A1 Journal article – refereed

Place of publication:

Keywords:
Biomedical imaging, interferometry, layered dielectric structures, nondestructive testing, solid-state terahertz (THz) pulsed source, THz active imaging

Published:

Full citation:
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

DOI:
https://doi.org/10.1109/TTHZ.2020.3003500

Read the publication here:
http://urn.fi/urn:nbn:fi-fe2020111891005