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Updated: Jul 4, 2026

Method Development for Contactless Resonant Cavity Dielectric Spectroscopic Studies of Cellulosic Paper
Published on: October 4, 2019
Diagnosing water content in paper by terahertz radiation
D Banerjee1, W von Spiegel, M D Thomson
1Chair of Paper Technology and Mechanical Process Engineering (PMV), Technische Universität Darmstadt, Alexanderstr. 8, D-64283, Darmstadt, Germany.
Abstract:
We explore the application of terahertz spectroscopic techniques for the remote determination of the water content of paper. The aim is the development of a rapid diagnostic imaging tool applicable in paper fabrication processes. THz radiation offers a high sensitivity for water, a good spatial resolution, and insensitivity to scattering at the paper surface. The advent of THz cameras makes fast large-area image detectors feasible. In this paper, we show for the case of a 0.6-THz fixed-frequency system, that the water content of paper can be determined with high accuracy. We demonstrate a quantitative (calibrated) method for determining the moisture content in paper based on extinction and phase measurements in the lower THz range with a spatial resolution in the mm-range and scanning times below two minutes.
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