Standoff chemical detection using quantum cascade lasers and photoacoustic sensing techniques

Chen, Xing; Janssen, Douglas; Kostov, Dan; Choa, Fow-Sen

doi:10.1364/cleo_at.2011.jmc1

Cited by 1 publication

(2 citation statements)

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“…Later, we also added a 10 cm diameter sound reflector to the microphone, as seen in Figure 5c, to enhance sound collection efficacy. This increased the detection distance to 35 cm with a 10 dB Signal-to-Noise Ratio [24]. Next, Figure 5d shows that we replaced our microphone with a microphone that has higher sensitivity and larger sized parabolic sound reflector in the same experimental setup and we achieved a higher detection distance of 5.2 m. In our final indoor experiment, on adding a lock-in amplifier to our setup, we successfully reported detection from 41 feet (12.5 m).…”

Section: Preliminary Work Reviewmentioning

confidence: 99%

“…For example, we demonstrated PA standoff detection of TNT (trinitrotoluene), RDX (research department explosives) and nerve gas stimulant i.e., IPA (isapropanol) vapor. Figure 2 shows one such experiment where QCL was targeted at TNT and a microphone, with the parabolic sound reflector, detected the TNT with a strong SNR (above 10 dB) from a standoff detection distance of 8 feet [24][25][26][27]. Moreover, we improved our PA sensing systems' performance by replacing a single microphone element with an acoustic beam array of multiple microphone elements.…”

Section: Introductionmentioning

confidence: 99%

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Stand-Off Chemical Detection Using Photoacoustic Sensing Techniques—From Single Element to Phase Array

et al. 2018

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Abstract:Technologies that can detect harmful chemicals, such as explosive devices, harmful gas leaks, airborne chemicals or/and biological agents, are heavily invested in by the government to prevent any possible catastrophic consequences. Some key features of such technology are, but not limited to, effective signal-to-noise ratio (SNR) of the detected signal and extended distance between the detector and target. In this work, we describe the development of photoacoustic sensing techniques from simple to more complex systems. These techniques include passive and active noise filters, parabolic sound reflectors, a lock-in amplifier, and beam-forming with an array of microphones; using these techniques, we increased detection distance from a few cm in an indoor setting to over 41 feet in an outdoor setting. We also establish a theoretical mathematical model that explains the underlying principle of how SNR can be improved with an increasing number of microphone elements in the phase array. We validate this model with computational simulations as well as experimental results.

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Section: Preliminary Work Reviewmentioning

confidence: 99%