Detection and inspection device of illicit drugs in sealed envelopes using THz waves

We had proposed and developed a THz-wave apparatus for the nondestructive detection of illicit drugs and hazardous substances hidden in sealed envelopes. In actual inspection, we have proposed the following procedure: First, X- ray pre-inspection is carried out; second, the measurement of scattered THz waves is applied to pick up suspicious mails; and, third, the identification of the drugs is done by spectral fingerprinting. In this paper, our recent developments of this application and the prototype apparatus for the inspection will be presented.