Scientists are a step closer to creating a cloaking device after making an object visible to the naked eye disappear for the first time.

In the past, researchers have only been able to "cloak" microscopic objects using extremely complicated physics and so-called meta-materials made on a tiny scale.

But a new study at the University of Birmingham in the UK has taken a major step forward by making a paper clip invisible - an object thousands of times bigger than in previous experiments.
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The research works by using a naturally forming crystal called calcite which has extraordinary light-bending abilities.

By placing the crystals over an object it "bounces" light around it rendering it invisible to the naked eye.

Dr Shuang Zhang, a physicist and lead investigator on the University of Birmingham team, said: "This is a huge step as, for the first time, the cloaking area is rendered at a size that is big enough for the observer to 'see' the invisible object with the naked eye.

"By using natural crystals for the first time, rather than artificial meta-materials, we have been able to scale up the size of the cloak and can hide larger objects, thousands of times bigger than the wavelength of the light."

The new technique is limited only by the size of the naturally formed crystals.

Calcite crystals can be up to 21ft long, so it could be used on a car or a military vehicle.

It may also be possible to manufacture crystals with similar qualities.

Dr Zhang explained: "Previous cloaks have succeeded at the micron level - which is much smaller than the thickness of a human hair - using a nano- or micro-fabricated artificial composite material.

"It is a very slow process to make these structures and they also restrict the size of the cloaking area.

"We believe that by using calcite, we can start to develop a cloak of significant size that will open avenues for future applications of cloaking devices," Dr Zhang said.

The research is published this week in the journal Nature Communications.

The Telegraph, London