Non-destructive inspection of chemicals in mail envelopes using an injection-seeded terahertz-wave parametric generator

The injection-seeded terahertz parametric generator (is-TPG) is suitable for the non-destructive inspection of illicit drugs and explosives concealed in mail because of its high power generation and sensitive detectors. This study examined a terahertz (THz) spectrometry method suitable for the non-destructive detection of chemicals concealed in mail envelopes. We compared the transmission spectra of three saccharides in different covering materials using is-TPG and terahertz time-domain spectroscopy (THz-TDS).