Hand-held laser pointers can now be used for something else besides doing presentations, projecting images of microorganisms, and disabling satellites. Next week, a group of scientists from Israel’s Ben-Gurion University of the Negev will be presenting a compact device that they created, which uses a garden-variety green laser pointer to detect dangerous substances such as explosives.
The device is a particularly small, inexpensive version of a Raman spectrometer.
These work by shining a highly-focused beam of light, at a specific wavelength, onto a sample of material. That material scatters the light. While most of the scattered light retains its original qualities, some of it experiences a shortening or lengthening of its wavelength, which is caused by the unique properties of the material. By detecting this altered wavelength and then comparing it to that of the originally-emitted light, the spectrometer is able to identify what chemicals are present in the sample.
While such spectrometers can be relatively large and expensive, the use of the consumer-grade laser pointer helped bring down the size and cost of the Israeli device – it also decreased its power requirements. Additionally, the laser’s short wavelength reportedly makes it easier for the device to detect the scattered light.
On top of that, the spectrometer is able to perform an initial optical scan of the entire sample, looking for areas of interest to analyze with the laser. Ordinarily, such a task would have to be performed using a separate Raman microscope.
Schematic drawing of the Raman spectrometer, including a laser pointer, dichroic mirror, prism, objective, x,y motorized translational stage, long wavepass edge filter, lens and a detector
“Since the overall system is modular, compact, and can be readily made portable, it can be easily applied to the detection of different compounds and for forensic examination of objects that are contaminated with drugs, explosives, and particularly explosive residues on latent fingerprints,” said Ilana Bar, a researcher on the project. “With proper investment, this system could be deployed quite quickly as a consumer product.”
The Ben-Gurion scientists will be presenting their research next Thursday in Rochester, New York, at Laser Science XXVIII - the American Physical Society Division of Laser Science’s Annual Meeting.
Source: The Optical Society