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article imageDeploying lasers to sniff out toxic gas

By Tim Sandle     Nov 1, 2016 in Science
The days of using dogs to sniff out toxic substances could be about to end. Scientists have pioneered a new approach for toxic gas detection based on infrared lasers, and the scientific explanation is at the quantum level.
The new approach for the simultaneous detection of multiple toxic substances involves the use of infrared lasers (a type called “quantum cascade lasers"). The method involves transmitting a laser beam through the gas so that the beam is registered by an adjacent separate detector. The identification of the gas measures the degree of light attenuation it causes.
A ring-system is involved. With this, one ring emits the laser light. This light moves through the gas and is then reflected back by a mirror. A second ring then receives the reflected light and measures its strength.
In terms of what is happening as the laser moves through the gas, electrons are passing through the laser. As this happens, electrons lose some of their energy. The degree of energy loss depends on the material that they pass through (in this case gases made of different molecules). To obtain the necessary degree of sensitivity, the device required the laser to emit light at a very specific wavelength.
Because different gases only absorb very specific amounts of infrared light, this property enables the detector to sense and interpret the constituents of the gas. In other word, each gas has its own light variable ‘fingerprint.’
The device was developed by Professor Rolf Szedlak of the institute Technische Universität Wien. The advantage of the device is based on its size (it is portable) and its ability to assess a gas for a range of different potentially toxic substances.
In a research note, Professor Szedlak, who specializes in solid state electronics, explains: “The lasers that we produce are a far cry from ordinary laser pointers. “We make what are known as quantum cascade lasers. They are made up of a sophisticated layered system of different materials and emit light in the infrared range.”
The device, once commercialized, offers the potential for the rapid assessment of potentially toxic gas clouds. The research is published in the journal ACS Photonics, in a paper titled “Remote Sensing with Commutable Monolithic Laser and Detector.”
More about Toxic gas, Quantum physics, Gas, Toxins, Sensor
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