Terahertz Sensing For Bomb Detection

American scientists are developing new optical sensing equipment that could promise a huge technological step-change in bomb detection and other security applications.

Researchers at Renssaelaer Polytechnic Institute are analysing the way objects emit naturally-occurring Terahertz radiation waves. They believe that by analysing the shape of these waves, they will be able to determine the type of object they're emanating from.

The scientists say this could potentially enable security services to undertake Terahertz sensing on suspicious objects, leading to a breakthrough in bomb and explosives detection.

Terahertz Sensing

Terahertz (THz) waves are naturally-occurring. Every object and substance emits them. The Rensselaer scientists have worked out a system of focusing two laser beams together in the air, creating a plasma that interacts with the natural THz waves. This creates a fluorescence which can be compared to the wave spectrum in the THz "library". This allows the material emitting the wave to be correctly identified. Scientists say the waves can be detected from up to 20 metres away using remote sensing equipment.

Dr Xi-Cheng Zhang, director of the Center for THz Research at Rensselaer, explained: "We have shown that you can focus a 800nm laser beam and a 400nm laser beam together into the air to remotely create a plasma interacting with the THz wave, and use the plasma fluorescence to convey the information of the THz wave back to the local detector."

Terahertz Bomb Detection

Although the technology is still at an embryonic stage and purely lab-based, the researchers believe it can become portable, meaning it has clear potential for security agencies in the future. The team says portable Terahertz sensors could become a new way of by airport security to check suspicious items for any explosives or detect chemical spills, say the team. They say it's ideal because it allows previously hidden materials to become visible.

"I think I can predict that, within a few years, the THz science and technology will become more available and ready for industrial and defense-related use," Dr Zhang added.

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