Scientists have shown how a technology called terahertz spectroscopy could be used to help spot fake clothing and combat textile counterfeiting.

The technique involves placing a sample of fabric is then placed within a beam of terahertz radiation - a band of electromagnetic radiation that falls between microwaves and infrared light.

The properties of the terahertz waves are detected after passing through the fabric, with the composition and structure of the different types of fabric giving rise to different rates of beam scattering and absorption.

This means that each type of fabric has a distinct transmission profile associated with it, essentially giving it a signature. The detection of this signature could indicate whether or not the fabric in question is counterfeit.

The research by scientists from the National Physical Laboratory (NPL) is published in Applied Optics.

It examined fabrics made from wool, cotton, linen, silk and mixed fibres - all of which demonstrated distinct terahertz transmission properties.

The technique could clearly distinguish between fabrics that looked and felt similar but 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.

The research was carried out in collaboration with the Institute of Monitoring of Climatic and Ecological Systems in Russia.