We propose an optical technique for the fast check of the presence, on the exposed surfaces of persons and objects, of explosives and their precursors, or drugs, or in general materials which are not allowed in restricted environments: airports, courts, places of worship, etc. The technique yields bi-dimensional pictures, with exposure time of < 1 sec, reporting the target substances, and their locations and quantities. The technique already provided laboratory preliminary results, to be completed, and fully validated for sensitivity and selectivity. The device could be used stand-alone, or integrated in the microwave sensors for the detection of hidden dangerous objects.
The present techniques, yielding physical information (eg. metal detectors for ferrous materials, or radiofrequency detectors for blunt or cutting instruments) are used on all people crossing checkpoints. On the contrary, chemical detectors are used randomly, as they require sticking substrates, to be transferred to the analizer. These latter techniques are slow, and do not guarantee a full screening. Moreover, also the checked people are not fully inspected, but only on some points. The proposed technique allows a full chemical check on all people in transit, in very short time. As a perspective, when raising the acquisition speed, the technique could be applied on (slowly) moving people, so dramatically reducing the checking time. This improvement would allow new applications, such as crowded sport or music events.