Laser beams help detect chemicals over long distances
28 Feb 2012
Researchers at the Vienna University of Technology have developed a method of detecting chemicals with a laser over a distance of more than a hundred meters.
The technique could allow engineers to keep a safe distance from explosive substances while still being able to analyse them effectively. The researchers claim this will open up a range of new applications in the chemical industry.
The method centres on the use Raman-spectroscopy to analyse the way laser light behaves in different substances.
When light is scattered, it can change its energy. For example, the photons can transfer energy to the molecules by exciting molecular vibrations. This changes the wavelength and colour of the light.
“Among hundreds of millions of photons, only a few trigger a Raman-scattering process in the sample”, explained Prof Bernhard Zachhuber, who is leading the EU-funded project.
The particles of light are scattered uniformly in all directions and a tiny fraction travel back to the light detector. From this very weak signal, a highly efficient telescope and extremely sensitive light detectors extract as much information as possible.
“Until now, the sample had to be placed very close to the laser and the light detector for this kind of Raman-spectroscopy”, said Zachhuber.
The team at TU Vienna are collaborating with organisations including the Spanish Guardia Civil and the Austrian military to develop the system further.
