Penetrating Terahertz Hyperspectral Unmixing via Löwner-John Ellipsoid (THz HU-LJE): An Unsupervised Algorithm

We presented an unsupervised method to separate mixtures of penetrating hyperspectral THz signals, using Löwner-John ellipsoid and THz time-domain spectroscopy. Its efficacy was demonstrated in the substance system composed of chemical pellets. Compared with contemporary THz spectral unmixing methods, we blindly extracted broadband spectral signatures of pure components with significantly higher accuracy of material identification without prior knowledge/modeling of the signature.