Laser holograms to keep forgers at bay

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Media captionResearchers are etching holograms directly onto the surface of the metal

Scientists at Heriot-Watt university in Edinburgh have developed a new technique to fight counterfeiting. It uses high powered lasers to etch tiny 3D holograms directly onto metal objects to create security marks that can't be copied or peeled off. The researchers are sculpting the holograms using high powered laser pulses measured in billionths of a second.

I keep a Rolex in my sock drawer. Well it says Rolex on the face of the watch.

But given that it doesn't tick like one - and I bought it in a street market in Kuala Lumpur for a fiver - it would be remarkable if it wasn't a fake.

If only all counterfeiters were as unsophisticated. They're copying not just expensive watches, but electronics and even aircraft parts.

The potential dangers don't bear thinking about. But Prof Duncan Hand has come up with a countermeasure.

He leads Heriot-Watt's research into the applications of high power lasers in manufacturing and medicine.

"It's about making holographic structures directly onto the surface of the metal," he says.

"Rather than have a stick-on hologram as you may have seen on many devices, instead inscribing that hologram directly on the surface.

"So it's much harder for someone to replicate it."

Image caption The hologram pixels are 10 microns across

In the lab, research associate Dr Krystian Wlodarczyk is using a powerful ultraviolet laser to sculpt a 3D hologram into a piece of metal. He show me the results.

"Here we have a set of very shallow, very small, optically smooth craters which are arranged in a particular pattern.

"So when we illuminate this hologram with a collimated beam - for example a low cost, commercially available laser pointer - it generates a diffractive image."

Dr Wlodarczyk produces just such a pointer. He bounces the beam off the hologram and shines an image on the wall.

In this case it reads "Hi BBC" because he's made it in honour of our visit.

Each hologram produced this way can be unique, tamper proof and difficult - if not impossible - to replicate.

Tiny craters

The key to the process is control of the laser. Prof Hand runs through some of the tiny distances - and times - they're working with.

"Essentially what you're doing is melting a very thin layer of the metal in a very small area.

"You're doing that with a pulse from the laser that is only 35 nanoseconds long.

"If you compare that to a second, it's like a second compared to a year."

Each pulse creates a tiny crater in the surface of the metal.

How tiny? Professor Hand again: "I'm making craters that are 0.2 microns in depth. Now a micron is one thousandth of a millimetre.

"In diameter they're about 10 microns.

"And we're making multiples of these craters across the surface in order to create our pattern for our hologram."

The Heriot-Watt team is already working with commercial partners to bring the technique to market.

Real deal

The likely first application takes us back to that fake Rolex.

"The applications particularly are in jewellery, for example in expensive watches," Prof Hand says.

"Also it could be used in the aerospace industry for spare parts for aeroplanes, to confirm that they're real parts made by the real manufacturer."

The researchers are developing the technique to work on glass - and to create even smaller security marks.

With counterfeiters prepared to fake virtually anything provided there's money in it, it offers the makers of genuine products the chance to prove they're the real deal.

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