초록 ▼

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. Such illumination has sufficient intensity and duration to cause selective desorption of mole

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. Such illumination has sufficient intensity and duration 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 as indicative of the detection of the contraband substance, and activates a signaling device to provide an audible or visible alarm. The apparatus rapidly detects the presence of a wide variety of contraband substances in an accurate, reliable manner. It provides for automated screening, with the result that vagaries of human performance are virtually eliminated. False alarms are reduced and detection efficacy is increased. A traceable residue of the detected contraband is left on the article for use in forensic analysis.

대표청구항 ▼

What is claimed is: 1. 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 inf

What is claimed is: 1. 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 molecules being thermally decomposed to produce NO2 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 molecules collected by said collection system; and an outlet for release of said air, 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 NO2 within said reaction cell, and for outputting an electrical signal indicative of the detection of said light; and f. signal means for indicating the presence of said NO2 produced by the decomposition of said contraband substance, said signal means being operably connected to said light detector and responsive to the receipt of said electrical signal. 2. A system as recited by claim 1, wherein said contraband substance comprises an organo-nitro explosive. 3. A system as recited by claim 1, wherein said intensity and duration of said illumination is such that at least a portion of said contraband substance is thermally decomposed to produce molecules of NO2. 4. A system as recited by claim 1, wherein said intensity and duration of said illumination is such that at least a portion of said desorbed molecules is comprised in particles of said contraband substance ablated from said surface by said illumination. 5. A system as recited by claim 1, said collection system comprising an air pump for urging said desorbed molecules through said collection system and into said reaction cell. 6. A system as recited by claim 1, said collection system comprising a collection substrate on which molecules entering said collection system are accumulated and a heater to cause desorption of said accumulated molecules from said substrate. 7. A system as recited by claim 1, further comprising: g. a pyrolyzer located between said aperture of said collection system and said inlet of said reaction cell and containing a catalyst for pyrolyzing molecules of said contraband substance to produce NO2. 8. A system as recited by claim 1, wherein said catalyst is a heated wire comprising Pt. 9. A system as recited by claim 8, wherein said heated wire consists essentially of a Pt--Rh alloy. 10. A system as recited by claim 1 wherein said solution comprises luminol present at a concentration ranging from about 0.3 to 3 mM. 11. A system as recited by claim 1 wherein said solution comprises KOH present at a concentration ranging from about 10-3 to 5 M. 12. A system as recited by claim 1 wherein said solution comprises at least one sulfur compound present at a concentration ranging from about 10-3 to 0.1 M, said compound being selected from the group consisting of Na2S, Na2S2O4, and Na2SO3. 13. A system as recited by claim 1, wherein said solution comprises 1 mM luminol, 1 M KOH, and 0.1 M Na2SO3. 14. A system as recited by claim 1, wherein said solution further comprises a chemiluminescence enhancer. 15. A system as recited by claim 1, wherein said solution further comprises a lower alcohol. 16. A system as recited by claim 1, further comprising a semi-permeable, hydrophobic membrane separating said luminol-containing solution from said reaction zone. 17. A system as recited by claim 16, wherein said hydrophobic membrane consists essentially of at least one of PTFE and polypropylene. 18. A system as recited by claim 16, wherein said hydrophobic membrane has a pore size ranging from about 0.1 to 8 μm. 19. A system as recited by claim 16, wherein said solution is provided in a replaceable cartridge and sealed therein by said semi-permeable, hydrophobic membrane. 20. A system as recited by claim 1, wherein said light detector comprises a photomultiplier tube. 21. A system as recited by claim 1, further comprising: h. a digital computer for controlling said apparatus and analyzing the output of said detector. 22. A system as recited by claim 1, further comprising: i. motion means for relatively moving said baggage item and said beam of light to illuminate an extended interrogation zone. 23. A system as recited by claim 22, wherein said motion means comprises at least one movable optically deflecting component in said optical system which movably deflects said light to illuminate said extended interrogation zone. 24. A system as recited by claim 23, wherein said optically deflecting component is at least one rotating mirror. 25. A system as recited by claim 22, wherein said motion means comprises a conveyor belt for moving said baggage item. 26. A system as recited by claim 22, wherein said beam of light is raster scanned over said extended interrogation zone. 27. A system as recited by claim 22, wherein said signal means comprises a computer display terminal adapted to display a mapping indicative of the locations on said baggage item at which a contraband substance has been detected. 28. A system as recited by claim 27, wherein said computer display terminal is adapted to display a visual representation of said baggage item and said mapping is a false color mapping superimposed on said visual representation. 29. A system as recited by claim 1, further comprising an optical filter interposed between said reaction cell and said light detector, said filter selectively transmitting light having a wavelength within a preselected range encompassing the wavelengths emitted by said reaction between said luminol and said NO2. 30. A system as recited by claim 7, wherein said pyrolyzer is pulse heated to a temperature ranging from about 300 to 800째 C. 31. A system as recited by claim 30, wherein said temperature ranges from about 500 to 700째 C. 32. A system as recited by claim 1, wherein said solution further comprises at least one alcohol selected from the group consisting of methanol, ethanol, propanol, isopropanol, and butanol. 33. A method of scanning at least a portion of the surface of a baggage item for the presence thereon of at least one contraband substance, the method comprising the steps of: a. illuminating an interrogation area of said surface with infrared laser light to selectively desorb molecules of said contraband substance; b. thermally decomposing at least a portion of said desorbed molecules to form NO2; c. passing said NO2 into a reaction cell, said reaction cell having a reaction zone and comprising an aqueous, alkaline, luminol-containing solution; d. reacting said NO2 in said reaction cell with said luminol to produce light and e. detecting said light; and f. signaling the detection of said light to indicate the presence of said contraband substance on the surface of said baggage item. 34. A method as recited by claim 33, said reaction cell further comprising a semi-permeable, hydrophobic membrane separating said luminol solution from said reaction zone. 35. A method as recited by claim 34, wherein said luminol solution is furnished in a replaceable cartridge sealed by said semi-permeable membrane. 36. A method as recited by claim 33, wherein said illumination has an intensity and a duration such that at least a portion of said contraband substance is thermally decomposed to produce molecules of NO2. 37. A method as recited by claim 33, wherein said illumination has an intensity and a duration such that a plurality of particles of said contraband substance are ablated from said surface by said illumination. 38. A method as recited by claim 33, further comprising the steps of: g. accumulating said desorbed molecules of said contraband substance on a collection substrate; and h. heating said collection substrate to cause desorption of said accumulated molecules from substrate. 39. A method as recited by claim 38, wherein said collection substrate comprises an adsorbent. 40. A method as recited by claim 33, further comprising the step of: i. pyrolyzing said desorbed molecules to form NO2.