Laser sampler offers automated testing
A laser system that automatically analyses water samples at the treatment works has been developed by researchers from the Fraunhofer Institute for Applied Solid State Physics IAF in Freiburg, Germany. The quantum cascade infrared laser forms the core of a water analysis system that can determine within a few minutes whether drinking water contains impurities and what those impurities are.
The system has been designed in order to enable immediate identification of dangerous substances. Using molecular spectroscopy, the researchers are able to examine the optical spectra of the molecules in the water.
Each chemical compound has a unique spectrum so individual molecules vibrate and absorb light at characteristic frequencies. Water itself is a very strong absorber of infrared light, but because light sources employed to date have delivered little power, examinations of this sort have been previously only been possible in a laboratory setting.
The quantum cascade laser produces light that is up to 1,000 times more concentrated than the silicon carbide thermal emitters used in the laboratory previously. Infrared radiation is emitted at longer wavelengths than the human eye canregister. For molecular spectroscopy, analysts are interested in wavelengths between 7.3 and 11 micrometers.
The researchers say that water samples will no longer need to be prepared in the laboratory, costing time and money. Instead, they can be taken in situ in the course of routine operations.
The measurement system is a little larger than a shoebox. It works automatically and requires hardly any maintenance.
Frank Fuchs, Fraunhofer IAF coordinator for the IRLSENS project, which is funded by Germany’s Federal Ministry of Education & Research (BMBF), said: “The equipment samples the water for dangerous substances at the waterworks itself in the course of routine operations, and allows for a rapid response.”
A technology demonstrator installed by project partner, instrumentation company BrukerOptik, at the KleineKinzig waterworks in the Black Forest, has proved successful. Tests were conducted on various concentrations of sweetener as a simulator substance.
Measurements were taken every three minutes over a period of six weeks with the fully automated system collecting a total of 21,000 samples. Providing there is sufficient demand, BrukerOptik says it would like to develop the measurement system into a finished product.
“If we see any such anomalies, this novel laser technology can quickly identify the dangerous substance on site and support water experts as they assess the situation,” concluded Fuchs.
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