Nondestructive identification of wood species by terahertz spectrum

Abstract

Terahertz time-domain spectroscopy (THz-TDS) has become an emerging nondestructive detection technique due to the unique properties of THz waves; it offers safety, penetrability, and fingerprint identification, especially for commonly used non-polar materials. Here, we measure the differences in THz spectra of four wood blocks (manglietia, amur linden, black walnut, and ebony) in the frequency range of 0.1-0.9 THz. In addition, we demonstrate the principal components analysis (PCA) applied in THz absorption spectra; the principal components extracted from original data by PCA can replace the original absorption coefficient data and can clearly distinguish the wood types. Results show that THz-TDS combined with PCA can be used as an effective nondestructive identification method in the field of public security, food detection, and customs antismuggling initiatives.

Chiral Metasurface Multifocal Lens in the Terahertz Band Based on Deep Learning

“…The special position of terahertz waves in the electromagnetic spectrum gives them the advantages of low photon energy, rich spectral information, and wide bandwidth. These features have resulted in terahertz waves being widely used in nondestructive flaw detection [1], safety inspection [2], medical imaging [3], and other fields. However, the size of the optics is a challenging issue in these applications.…”