Harry Potter fans will be delighted to know that efforts by researchers at Duke University in the U.S. have moved one step closer to making an invisibility cloak.

But it will still be a while before you can buy one. And, judging by the effort that goes into making one, it won’t come cheap.

Nevertheless… A team led by professor David Smith (pictured at right with his latest invention) has succeeded in bending light around an object — well, more like a bump, as Smith describes it — with no distortion or scattering. That’s a first.

As Smith told CNet.com this week: “The difference between the original device and the latest model is like night and day. The new device can cloak a much wider spectrum of waves — nearly limitless — and will scale far more easily to infrared and visible light. The approach we used should help us expand and improve our abilities to cloak different types of waves.”

The cloak is composed of a fiberglass composite ‘metamaterial’ specifically designed for the task. The effect it produces is described as similar in some ways to the mirage we’ve all seen hovering above a hot asphalt highway in mid summer.

Far from providing wizards or spies with the ability to pass unseen, Smith explains that — initially, at least — his cloaking device will probably be used to bend invisible frequencies of electromagnetic radiation, such as radio waves, eliminating line-of-sight obstructions that can block transmissions.