High-sensitivity detection of trace gases using dynamic photoacoustic spectroscopy
Author(s)Wynn, Charles M.; Palmacci, Stephen; Clark, Michelle L.; Kunz, Roderick R.
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Lincoln Laboratory of Massachusetts Institute of Technology has developed a technique known as dynamic photoacoustic spectroscopy (DPAS) that could enable remote detection of trace gases via a field-portable laser-based system. A fielded DPAS system has the potential to enable rapid, early warning of airborne chemical threats. DPAS is a new form of photoacoustic spectroscopy that relies on a laser beam swept at the speed of sound to amplify an otherwise weak photoacoustic signal. We experimentally determine the sensitivity of this technique using trace quantities of SF[subscript 6] gas. A clutter-limited sensitivity of ~100 ppt is estimated for an integration path of 0.43 m. Additionally, detection at ranges over 5 m using two different detection modalities is demonstrated: a parabolic microphone and a laser vibrometer. Its utility in detecting ammonia emanating from solid samples in an ambient environment is also demonstrated.
Wynn, Charles M., Stephen Palmacci, Michelle L. Clark, and Roderick R. Kunz. “High-sensitivity detection of trace gases using dynamic photoacoustic spectroscopy.” Optical Engineering 53, no. 2 (February 1, 2014): 021103.
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