Quantum cascade lasers help fight against terrorism

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The Pacific Northwest National Laboratory has developed a highly accurate method of detecting nerve gas using quantum cascade lasers. Tests have shown the Quartz Laser Photo-Acoustic Sensing technique to be able to detect one liquid drop of liquid nerve gas in the size of two Olympic swimming pools.

The device uses an extremely sensitive form of absorption spectroscopy that creates a tiny acoustic signal when a pulsed laser beam is absorbed by a gas. The lasers are paired with quartz ‘tuning forks’ that act as a microphone to record the resulting sound wave.

The quantum cascade lasers allow analysis at the wavelength range of three to 12μm. Nearly every molecule has a unique fingerprint within this range, allowing the high degree of accuracy. The device is now ready for prototyping and testing before it will be available for general use.