Laser technique provides tamper-proof marking of metals

Researchers at Heriot-Watt University have developed a way to etch 3D holograms directly onto metal objects.

The tamper-resistant holograms - which cannot be removed without damaging or defacing the item - are created using high-powered lasers and could help protect high-value goods such electronics and aviation parts from counterfeiting.

Using an ultraviolet (UV) nanosecond-pulsed laser, the team led by Professor Duncan Hand - director of Heriot-Watt's School of Engineering & Physical Sciences - showed they could etch holograms onto the surface of metals by melting away the surface to produce optically-smooth impressions.

Unlike current anti-counterfeit methods such as printed serial numbers, bar codes or polymer holographic stickers, the marks cannot be removed. The team is in the process of testing the technique on a number of different metals.

Dr Krystian Wlodarczyk, a researcher working on the project, said: "The holograms are visible to the naked eye and appear as smooth, shiny textures."

"They're robust to local damage and readable by using a collimated beam from a low-cost, commercially-available laser pointer, so border agencies or consumers won't need expensive technology to check an item's authenticity."

The holograms - termed laser-induced surface deformations (LISDs) - can also be authenticated using a smart phone, he added. The Heriot-Watt researchers are investigating how to make them smaller and whether they can be applied to other materials such as glass.

There are still obstacles to widespread adoption of the technology, including the fact that the holograms take around two and a half hours to etch at the moment. However, the team suggest that with modifications the marking time could be cut to around 20 seconds.

The research has been published in the Journal of Material Processing Technology.