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.

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

A1 Journal article – refereed

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

https://doi.org/10.1109/TTHZ.2020.3003500 http://urn.fi/urn:nbn:fi-fe2020111891005