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Green laser pointer finds traces of dangerous chemicals

12 Oct 2012

Real-time operation offers rapid benefits for security systems.

By using an ordinary green laser pointer, commonly found in offices and college lecture halls, an Israeli research team has developed a new and highly portable Raman spectrometer that detects extremely minute traces of hazardous chemicals - in real time.

The novel sensor’s compact design makes it an excellent candidate for rapid field deployment to disaster zones and areas with security concerns. The researchers will present their findings at Laser Science XXVIII — the American Physical Society Division of Laser Science’s Annual Meeting collocated with the Optical Society of America’s (OSA) Annual Meeting, Frontiers in Optics, which is taking place in Rochester, N.Y. next week.

Ilana Bar, a researcher at the Department of Physics at Ben-Gurion University of the Negev, Israel, commented, “With proper investment, we believe that this straightforward system could be deployed quite quickly as a consumer product.”

Raman spectrometers rely on highly focused beams of light delivered at precise wavelengths to illuminate small samples of materials. Very sensitive detectors then study the spectra of light that has been re-emitted, or scattered, by the sample. Most of this scattered light retains its original frequency or color, but a small percentage of the light is shifted slightly to higher or lower wavelengths, depending on the unique vibrational modes of the sample under study. By comparing the shifted and the original wavelengths, it is possible to determine the precise chemicals present in the sample.

The researchers brought this capability down to size by constructing their Raman spectrometer using a low-power and low-cost commercial green laser pointer. The green laser’s relatively short wavelength helps to improve the detection of the inherently weak Raman signal. The spectrometer also has the capability to first scan the entire sample optically, sweeping from side to side, to locate individual particles of interest – a task usually performed by large and cumbersome Raman microscopes.

“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,” added Bar.

“With proper investment this system could be deployed quite quickly as a consumer product.” Other members of the research team include Itamar Malka, Alona Petrushansky, and Salman Rosenwaks.

The presentation, which is entitled “Detection of Explosives and Latent Fingerprint Residues Utilizing Laser Pointer Based Raman Spectroscopy,” takes place on Thursday, October 18 at 2:30 p.m. EDT at the Rochester Riverside Convention Center in Rochester, N.Y., USA.

Frontiers in Optics 2012 is the Optical Society’s (OSA) 96th Annual Meeting and is being held together with Laser Science XXVIII, the annual meeting of the American Physical Society (APS) Division of Laser Science (DLS). The two meetings unite the OSA and APS communities for five days of quality, cutting-edge presentations, fascinating invited speakers and a variety of special events spanning a broad range of topics in optics and photonics—the science of light—across the disciplines of physics, biology and chemistry.

FiO 2012 will also offer a number of Short Courses designed to increase participants’ knowledge of a specific subject in the optical sciences while offering the experience of insightful teachers. An exhibit floor featuring leading optics companies will further enhance the meeting.

About the Author

Matthew Peach is a contributing editor to optics.org

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