Terahertz scanner identifies hidden explosives, drugs

Terahertz scanner identifies hidden explosives, drugs

Technology News |
By eeNews Europe

"In the electromagnetic spectrum, Terahertz waves are positioned between microwaves and infrared radiation, combining the benefits of both", explains professor René Beigang from Fraunhofer IPM. Much like microwaves, the low-energy Terahertz radiation can penetrate many materials like paper, wood, light clothing, plastics and ceramics. In addition, Terahertz waves create specific reflection spectra depending on the materials they are hitting. With appropriate software these spectra can be analysed and allow conclusions regarding the material. Plus, Terahertz waves differ from X-rays in that they are a non-ionising radiation and thus harmless for humans. This property makes Terahertz waves suitable for application in mail scanners.

The scanner devised by the researchers works like this: Letters and smaller parcels enter the machine through a flap and get exposed with Terahertz waves. According to the material specific parts of these waves are more or less absorbed, generating a very characteristic spectral distribution. The waves then hit a detector which feeds the signal into a computer. "Within seconds, the machine acquired a specific ‘fingerprint’ of the material irradiated with these waves", explains Thorsten Sprenger from Huebner GmbH. "The comparison with a data base allows a very accurate identification of the material under test". Case the letter contains explosives or drugs, the machine issues an alert signal. It can test mail items at a format of up to C4 and a thickness of up to 2 cm. At the recent Photonics West exhibition in San Francisco, T-Cognition received the prestigious PrismAward.

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