Abstract
We proposed a quantitative method to calculate water content of thin materials by terahertz (THz) imaging. First, we constructed a THz imaging system using a tunnel injection transit time (TUNNETT) THz wave generator with automatic scanning control. As a suitable imaging spatial resolution is necessary to accurately estimate water content and distribution in samples, we have improved the spatial resolution. Images of plant leaves under different conditions were taken using the THz imaging system. We have introduced an algorithm with the attenuation law of Lambert–Beer to calculate water contents from THz images. To verify the accuracy of this method, we also obtained images of a piece of cotton cloth with different contents of water. Comparison of the calculated values with the measured values obtained using an electronic balance showed that our method has a good possibility for measuring the water content of relatively thin materials by a noncontact and noninvasive method using THz images.