THz spectroscopic imaging of reagents hidden in a 56 dB attenuated cardboard box using is-TPG

In 2003, we reported the development of a THz spectroscopic imaging system using a terahertz (THz) wave parametric oscillator (TPO). The system has a dynamic range below four orders of magnitude, which enables it to identify reagents through thin envelopes using THz spectroscopic imaging. Recently, we succeeded in developing a high power and high sensitivity THz wave spectroscopic imaging system using injection-seeded THz parametric generation and detection, with a dynamic range of 100 dB. In the previous study, the THz spectroscopic imaging system could successfully identify reagents through 23 mm thick envelopes. In this study, we succeeded in identification of reagents in a thicker and more complicated box, which attenuates over 50 dB at 1.3 THz, by improving the analysis method.