Technology developed by the National Physical Laboratory (NPL) could help reverse the estimated £3.5bn lost each year through the production of counterfeit clothing.
The new technique – based on terahertz time-domain spectroscopy – will help customs officers ascertain whether items of clothing are fake, assisting them in the seizure and destruction of fake goods.
This technique, described in Applied Optics, requires the generation of a beam of terahertz radiation, which is a band of electromagnetic radiation that falls between microwaves and infrared light. A sample of fabric is then placed within this beam and the properties of the terahertz waves are detected after passing through the fabric.
The composition and structure of the different types of fabric give rise to different rates of beam scattering and absorption. Different fabrics posses a distinct transmission profile, which gives it a signature that indicates whether or not the fabric in question is counterfeit.
According to a statement, this research examined fabrics made from wool, cotton, linen, silk and mixed fibres, all of which demonstrated distinct terahertz transmission properties.
The technique could distinguish between fabrics that looked and felt similar but that had different compositions. It could, for example, tell the difference between plain wool and the more expensive merino wool, as well as between natural and synthetic silk.
The next stage will be to test batches of the same type of fabric from the same manufacturer in a potential collaboration. It is also necessary to create a database of the terahertz transmission properties of many different fabrics and to study further the relationship between these and the properties of the fabrics themselves.
‘Counterfeit clothes can look and feel almost exactly like the real thing and so customs officials need technological assistance to spot them,’ said John Molloy, who worked on the project at NPL. ‘Terahertz spectroscopy is a fast, safe and reliable test that could help safeguard one of the UK’s most valuable industries.’
The research was carried out in collaboration with the Institute of Monitoring of Climatic and Ecological Systems in Russia. The Applied Optics paper can be found here.