Polarization-controlled THz spectroscopic imaging for nondestructive inspection

We present a polarization-controlled terahertz (THz) wave spectroscopic imaging modality to investigate the anisotropy of the detected materials. The polarization of the emitted THz wave is controlled to be horizontal and vertical by changing the relative phase of the fundamental and second-harmonic waves in the two-color laser-induced air plasma THz generation configuration. The anisotropy of the industrial sprayed-on-foam-insulation (SOFI) is characterized by measuring its azimuthal angle dependent THz polarization response. This work demonstrated that THz wave polarization-controlled imaging technique can be used for highly sensitive industrial inspection and biological related characterization.