Terahertz for Mail Screening

TeraView’s Terahertz Pulsed Imaging (TPI™) is a non-destructive and non-contact technique that can image the sub-surface structure of many sample types such as tablets, plastics and composites. As terahertz radiation is not scattered significantly by soft materials like paper, it can be used to investigate the contents of envelopes and paper packages without opening.
For mail screening Terahertz Pulsed Imaging (TPI™)   can be used for two different applications.
In the example below, text was applied to paper using pencil, ballpoint and a laser printer. The pages were then placed in an envelope and scanned using Terahertz Pulsed Imaging (TPI™). The Terahertz images obtained are shown below. Whichever way the text was generated, Terahertz Pulsed Imaging (TPI™) was able to “read” the script from outside the package. In addition to mail screening TPI™ can be used to read the contents of valuable or delicate documents without having to unfold or open the item where damage might occur.

Envelope containing sheets of paper with text in pencil, ballpoint pen and laser print
In other mail screening applications, the aim is to identify materials or substances contained in a letter. These substances may be hazardous and cause harm to the recipient or could also be controlled substances being sent through the mail system. In either case, TPI™ is able to detect the presence of such materials. An added benefit of this technology is that most materials have distinct spectral fingerprints in the terahertz region. So the presence of the substance can be detected using TPI™ and terahertz spectroscopy can be used to determine its chemical identity.

TPITM cross sectional image of powder between sheets of paper.Terahertz spectra fingerprints of explosives