Laser optoacoustic detection of explosive vapors

Claspy, P. C.; Pao, Yoh‐Han; Kwong, S.; Nodov, Eugene L.

doi:10.1109/jqe.1975.1068987

Cited by 5 publications

(4 citation statements)

References 4 publications

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“…Claspy and coworkers (150) were the first to detect explosive vapors using PAS. Periodic heating with a chopped IR beam (5.8-6.7 μm) of a cell containing the vapor sample resulted in pressure fluctuations that were detected with a sensitive microphone.…”

Section: Pasmentioning

confidence: 99%

Laser-Based Detection Methods for Explosives

Munson¹,

Gottfried²,

Lucia³

et al. 2007

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Section: Pasmentioning

confidence: 99%

Laser-Based Detection Methods for Explosives

Munson¹,

Gottfried²,

Lucia³

et al. 2007

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“…[2][3][4][5][6][7][8][9][10][11][12] The low-power PA technique has been predominantly utilized in the field of spectroscopy, [11][12][13][14][15][16][17][18] with substantial applications in trace gas detection. 5,[19][20][21][22][23] It exhibited significantly higher sensitivity than most other techniques, [24][25][26][27] with concentration sensitivity in the parts per billion. [3][4][5]25,27 PA spectroscopy is a powerful analytical tool for examining the optical absorption properties of solids as it directly measures the energy absorbed by the material on exposure to light.…”

Section: Introductionmentioning

confidence: 99%

“…The typical PA cell used for spectroscopy cannot be used for high-resolution OR-PAM application as the sizes (in the range of a few millimeter to a few inches) and design of the chamber limits the focusing of light. 12,23,35,36 We also developed PA cell for spectroscopy studies. The PA cell was made using a bulk aluminum rod to avoid vibrational noise.…”

Section: Introductionmentioning

confidence: 99%

Low-power noncontact photoacoustic microscope for bioimaging applications

2017

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Abstract. An inexpensive noncontact photoacoustic (PA) imaging system using a low-power continuous wave laser and a kilohertz-range microphone has been developed. The system operates in both optical and PA imaging modes and is designed to be compatible with conventional optical microscopes. Aqueous coupling fluids are not required for the detection of the PA signals; air is used as the coupling medium. The main component of the PA system is a custom designed PA imaging sensor that consists of an air-filled sample chamber and a resonator chamber that isolates a standard kilohertz frequency microphone from the input laser. A sample to be examined is placed on the glass substrate inside the chamber. A laser focused to a small spot by a 40× objective onto the substrate enables generation of PA signals from the sample. Raster scanning the laser over the sample with micrometer-sized steps enables high-resolution PA images to be generated. A lateral resolution of 1.37 μm was achieved in this proof of concept study, which can be further improved using a higher numerical aperture objective. The application of the system was investigated on a red blood cell, with a noiseequivalent detection sensitivity of 43,887 hemoglobin molecules (72.88 × 10 −21 mol or 72.88 zeptomol). The minimum pressure detectable limit of the system was 19.1 μPa. This inexpensive, compact noncontact PA sensor is easily integrated with existing commercial optical microscopes, enabling optical and PA imaging of the same sample. Applications include forensic measurements, blood coagulation tests, and monitoring the penetration of drugs into human membrane.

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“…Kerr and Atwood first reported the use of lasers for photoacoustic gas detection, 14 and Claspy and co-workers applied the technique to detect explosive vapors. 15,16 Since then, many groups have applied the technique for detection of gases, liquids, and solids. 17 Despite the copious number of papers published on the photoacoustic detection of materials, only a few papers center on the laser photoacoustic spectroscopy of solid energetic materials by monitoring their sound emissions.…”

Section: Introductionmentioning

confidence: 99%

The Detection of Energetic Materials by Laser Photoacoustic Overtone Spectroscopy

Sausa

Cabalo²

2012

Appl Spectrosc

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Laser-based sensors offer high sensitivity and species selectivity with real-time capabilities for monitoring the vapors of some energetic materials. However, the extremely low vapor pressure of many solid energetic materials under ambient conditions impedes these sensors. In this paper, we report on a novel technique based on laser photoacoustic overtone spectroscopy to detect and differentiate solid 1,3,5-trinitrotoluene (TNT), 1.3.5-trinitro-1,3,5-triazacyclohexane (RDX), and 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (CL-20) in real time at ambient conditions. A tunable, near-infrared laser excites the target compound in the spectral region between 5800 to 6100 cm−1, and a microphone monitors the sound that they generate by non-radiative, collisional de-excitation processes. The photoacoustic signals result from first-overtone and combination absorptions of the energetic material's C–H vibrations, and the collisional processes enhance the signal at atmospheric pressure. The spectra reveal features that are unique to each measured material and these features can serve as a fingerprint for that material. We report the effects of laser energy and wavelength on signal intensity and estimate a detection limit for these compounds.

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Laser optoacoustic detection of explosive vapors

Cited by 5 publications

References 4 publications

Laser-Based Detection Methods for Explosives

Laser-Based Detection Methods for Explosives

Low-power noncontact photoacoustic microscope for bioimaging applications

The Detection of Energetic Materials by Laser Photoacoustic Overtone Spectroscopy

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