Extension of a standoff explosive detection system to CBRN threats

Ford, Alan; Waterbury, Rob; Rose, Jeremy; Pohl, Ken; Eisterhold, Megan; Thorn, Thelma; Lee, Keesoo; Dottery, Ed

doi:10.1117/12.849815

Cited by 5 publications

(3 citation statements)

References 7 publications

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“…Thus, a CO 2 laser is additionally used, which hits the target about 0.5 μs after the 266-nm pulse. An increase of the LIBS signal by a factor of 100-300 is the additional benefit of this technique (Townsend-effect plasma spectroscopy (61) ) which extends the useful investigation range to 40 m. (60,62) Recently, femtosecond (750 fs) fiber-laser-induced LIBS has been applied to detect explosive materials involving higher scanning speeds (40 mm s −1 ), pulse energies of 3 μJ, repetition rates of 225 kHz, and a wavelength of 1030 or 800 nm (Ti:sapphire). (48,63 -65) As usual, elemental constituents included C, H, N, and O; in addition, molar emissions from CN and C 2 are observed.…”

Section: Laser-induced Breakdown Spectroscopymentioning

confidence: 99%

Laser‐ and Optical‐Based Techniques for the Detection of ExplosivesUpdate based on the original article by David L. Monts, Jagdish P. Singh and Gary M. Boudreaux,Encyclopedia of Analytical Chemistry, © 2000, John Wiley & Sons, Ltd

Hummel

Dubroca

2013

Encyclopedia of Analytical Chemistry

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A wide variety of optical‐ and laser‐based techniques have been and are currently being investigated as means of identifying and characterizing explosive materials. These efforts are hampered by the very low volatility of explosive compounds at room temperature and their tendency to ignite at higher temperatures where their vapor pressures are beginning to reach a regime where the species can be readily detected. Traditional, condensed‐phase absorption spectroscopy (both infrared (IR) and ultraviolet/ visible (UV/VIS)) requires larger samples than are frequently available and, although useful as confirmatory techniques, do not provide signatures that enable unique identification of species. The choice of nontraditional techniques for analysis of explosive materials is dependent upon the amount of sample available, the sample matrix, and sample‐imposed constraints upon the measurement. Raman spectroscopy can identify and quantify condensed phase explosive materials, but the detection limit depends upon substrate, excitation wavelength, and illumination area: limits of detection (LODs) vary from 0.05 ng for 2,4,6‐trinitrotoluene (TNT) on glass to 10 µg for nitroglycerin (NG) on silica gel. The other detection techniques considered require volatilization of either the explosive compound itself or more often of characteristic decomposition products, such as NO, NO 2 , or N 2 O. Using IR irradiation, researchers have demonstrated that photoacoustic spectroscopy (PAS) has detection limits ranging from 0.55 ppb (parts per billion) for vapor‐phase NG with 9 mm excitation to 220 ppm (parts per million) for vaporphase 2,4‐dinitrotoluene (DNT) with 6‐µm excitation. IR laser differential absorption detection of dissociation products NO, NO 2 , and/or N 2 O can achieve detection limits of a few picograms. Laser‐induced fluorescence (LIF) detection of the photofragments (typically NO) of explosive compounds yields detection limits in the tens to hundreds of ppb (by weight) range. Low LODs can be achieved using ion detection techniques: resonance‐enhanced multiphoton ionization (REMPI) spectrometry is capable of LODs for detecting vapor‐phase explosives compounds in the hundredths to tens of ppb range; ion mobility spectrometry (IMS) has vapor‐phase detection limits for common explosive compounds of typically 200 pg, but for some species can be significantly lower: for example, 1 pg for TNT.

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Section: Laser-induced Breakdown Spectroscopymentioning

confidence: 99%

Laser‐ and Optical‐Based Techniques for the Detection of ExplosivesUpdate based on the original article by David L. Monts, Jagdish P. Singh and Gary M. Boudreaux,Encyclopedia of Analytical Chemistry, © 2000, John Wiley & Sons, Ltd

Hummel

Dubroca

2013

Encyclopedia of Analytical Chemistry

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“…3,4 However, there are many situations in which physical sampling is not feasible and it is highly desirable to perform noncontact and nondestructive testing at appreciable standoff distances (>1 m). 5 Of the demonstrated standoff detection methods, the most promising ones include laserinduced breakdown spectroscopy (LIBS), 6,7 Raman spectroscopy, [8][9][10] and long-wave infrared (LWIR) spectroscopy. 11,12 The LWIR approaches can be divided into those that are passive (utilizing ambient radiation) [13][14][15] and those that are active (utilizing illumination).…”

Section: Introductionmentioning

confidence: 99%

Laser-based long-wave-infrared hyperspectral imaging system for the standoff detection of trace surface chemicals

et al. 2020

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A trace chemical detector is described that combines external-cavity quantum cascade lasers and a mercury cadmium telluride camera to capture hyperspectral images of the diffuse reflectance from a target surface in the long-wave infrared. The system is able to generate individual hypercubes in <0.1 s. When raster scanning the laser beam over the target surface, areal coverage rates of >60 cm 2 ∕s have been achieved. Results are presented for standoff distances ranging from 0.1 to 25 m. Hyperspectral images generated by the system are analyzed for spectral features that indicate the presence of trace surface contaminants. This approach has been found to be highly capable of detecting trace chemical residues on a wide variety of surfaces, and we present a collection of detection results to demonstrate the capabilities of this technology. Examples include the detection of 10 μg of saccharin powder on a wide range of substrates, 0.2 μg of an explosive residue on a computer keyboard, residual pharmaceuticals within a plastic baggie, and a contaminated fingerprint on cell phone case. © The Authors. Published by SPIE under a Creative Commons Attribution 4.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.

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“…Instead, a non-ablative, defocused or collimated, second laser pulse, in the midinfrared (IR) regiontypically a carbon dioxide (CO2) transversely excited atmospheric (TEA) laser operating at 10.6 μmis used to re-excite the plasma [30][31][32]. Whereas DP-LIBS routinely provides enhancements close to an order of magnitude, TEPS can create enhancements close to two orders of magnitude in some cases under long irradiance [33,34]. Though not certain, the larger enhancement is possibly due to plasma reheating in an airrarefied region, as is common in DP-LIBS using only near-IR wavelengths [32,[35][36][37].…”

Section: Introductionmentioning

confidence: 99%

Mid-IR enhanced laser ablation molecular isotopic spectrometry

Brown

Ford

Akpovo

et al. 2016

Spectrochimica Acta Part B: Atomic Spectroscopy

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A double-pulsed laser-induced breakdown spectroscopy (DP-LIBS) technique utilizing wavelengths in the mid-infrared (MIR) for the second pulse, referred to as double-pulse LAMIS (DP-LAMIS), was examined for its effect on detection limits compared to single-pulse laser ablation molecular isotopic spectrometry (LAMIS). A MIR carbon dioxide (CO2) laser pulse at 10.6 μm was employed to enhance spectral emissions from nanosecond-laser-induced plasma via mid-IR reheating and in turn, improve the determination of the relative abundance of isotopes in a sample. This technique was demonstrated on a collection of 10 BO and 11 BO molecular spectra created from enriched boric acid (H3BO3) isotopologues in varying concentrations. Effects on the overall ability of both LAMIS and DP-LAMIS to detect the relative abundance of boron isotopes in a starting sample were considered. Least-squares fitting to theoretical models was used to deduce plasma parameters and understand reproducibility of results. Furthermore, some optimization for conditions of the enhanced emission was achieved, along with a comparison of the overall emission intensity, plasma density, and plasma temperature generated by the two techniques.

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Extension of a standoff explosive detection system to CBRN threats

Cited by 5 publications

References 7 publications

Laser‐ and Optical‐Based Techniques for the Detection of ExplosivesUpdate based on the original article by David L. Monts, Jagdish P. Singh and Gary M. Boudreaux,Encyclopedia of Analytical Chemistry, © 2000, John Wiley & Sons, Ltd

Laser‐ and Optical‐Based Techniques for the Detection of ExplosivesUpdate based on the original article by David L. Monts, Jagdish P. Singh and Gary M. Boudreaux,Encyclopedia of Analytical Chemistry, © 2000, John Wiley & Sons, Ltd

Laser-based long-wave-infrared hyperspectral imaging system for the standoff detection of trace surface chemicals

Mid-IR enhanced laser ablation molecular isotopic spectrometry

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