Using lasers and tuning forks, researchers at Pacific Northwest National Laboratory have developed a chemical weapon agent sensing technique called Quartz Laser Photo-Acoustic Sensing (QPAS) that promises to meet or exceed current and emerging defense and homeland security chemical detection requirements.
The instrument is based on Laser Photo-Acoustic Sensing (LPAS) and infrared Quantum Cascade Lasers (QCLs). LPAS is a very sensitive form of optical absorption spectroscopy, where a pulsed laser beam creates a brief absorption in a sample gas, which in turn creates a very small acoustic signal. A miniature quartz tuning fork acts as a "microphone" to record the resulting sound wave.
A conceptual design for a battery-operated, prototype QPAS sensor, which includes 10 pairs of QCLs and tuning forks, would fit into a briefcase that is 12 x 12 x 6". The entire device would weigh less than 15 pounds.
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