In 2003, we demonstrated a non-destructive terahertz spectroscopic imaging of illicit drugs hidden in envelopes using a widely tunable THz-wave parametric source , though its dynamic range at that time was less than four orders. Recently, we have realized ten orders of dynamic range with an evolved injection seeded THz-wave spectrometer. Now we can detect drugs under much thicker obstacles than before. In this report, we introduce related topics; i) Enhanced tuning range up to 4.7 THz, ii) >90dB dynamic range THz detection using near infrared detector, iii) Comparison between is-TPG spectrometer and TDS, iv) THz Spectroscopic imaging.
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