A compact scanning apparatus has an
infrared laser adapted to emit light. The light is delivered as a beam by an optical
system to illuminate an interrogation area on the surface of an object being scanned to cause selective
desorption of molecules of the contraband substance, which are present on the surface, without substantially damaging the surface. A
collection system collects at least a portion of the desorbed molecules. At least a portion of the collected molecules is thermally decomposed to form NO2 and transferred to a reaction
cell containing an aqueous, alkaline,
luminol-containing solution. The NO2 reacts with the
luminol to produce light by
chemiluminescence. A
light detector registers the presence of this light to carry out a rapid screening of the object for the possible presence of the contraband substance. The apparatus further includes a supplemental
detector such as a GC / IMS
detector that is activated in response to the detection of the chemiluminescent light. The supplemental
detector provides confirmation of the detection of contraband substance and activates a signaling device to provide an audible or visible alarm. The rapid pre-screening permits the apparatus to identify suspicious items, while the supplemental detection
system can be optimized for more intense, but time-consuming scrutiny of just the suspicious items. Both effective detection and high
throughput are thereby achieved in an accurate, reliable manner.