Remote detection of explosive traces using Raman and MIR laser spectroscopy

Kurzfassung

The detection of hazardous and illicit substances, such as explosives, plays a key role in security applications. Laser based techniques are already being used for the detection of illegal narcotics, and hazardous chemicals as well as for quality control of pharmaceutical and chemical products. Applications for security checks at airports or public buildings are often discussed, however, many examples only reach a test phase. The list of requirements for real-life applications is long, including standards regarding sensitivity and false alarm rates, but also more practical challenges such as applicability in a wide range of different environments and scenarios or operational simplicity and maintenance intervals. We have designed a standoff detection system that uses UV Raman and mid-infrared spectroscopy to detect traces of explosives during security checks. A camera paired with an image recognition algorithm detects people stepping in front of the device and aligns the spectroscopic sensors to examine the surfaces of their shoes. The contactless detection of explosive traces at distances of ~1 meter is complete within seconds. During the ongoing development of the system we have investigated the spectroscopic sensitivity in a laboratory environment as well as in an outdoor venue. First results are very encouraging and involve a small number of explosives on different surfaces ranging from quartz and car panels to textiles. Both, Raman and mid-infrared spectroscopy results are presented and discussed.