Patent ID: 6946300

Claim:
A system for screening at least a portion of the surface of a baggage item for the presence thereon of a contraband substance, the system comprising: a) an infrared laser adapted to emit light; b) an optical system adapted to deliver a beam of said light emitted from said infrared laser to illuminate an interrogation area of said surface, said illumination having sufficient intensity and duration to cause selective desorption of molecules of said contraband substance present within said interrogation area without substantially damaging said surface, and at least a portion of said desorbed molecules being thermally decomposed to produce NO 2 molecules; c) a collection system having at least one aperture and being adapted to collect at least a portion of said desorbed molecules through said aperture; d) a reaction cell in communication with said collection system, said reaction cell having a reaction zone, an inlet for receiving in said reaction zone said desorbed molecules collected by said collection system; and an outlet for release of said desorbed molecules, and said reaction cell containing an alkaline, aqueous luminol-containing solution; e) a light detector for detecting light produced chemiluminescently by a chemical reaction between said luminol and said NO 2 within said reaction cell, and for outputting a first electrical signal indicative of the detection of said light; f) a supplemental detector in communication with said collection system for detecting said contraband substance and for outputting a second electrical signal indicative of the detection of said contraband substance; g) signal means for indicating the presence of said NO 2 produced by the decomposition of said contraband substance, said signal means being operably connected to said light detector and said supplemental detector and responsive to the receipt of said first or second electrical signals.