德國科學家發明3D"隱形斗篷"

German scientists have created a three-dimensional "invisibility cloak" that can hide objects by bending light waves.

The findings, published in the journal Science on Thursday, could in the future make it possible to make large objects invisible, but for now the researchers said they were not keen to speculate on possible applications.

"For now king devices are just a beautiful and exciting benchmark to show what transformation optics can do," said Tolga Ergin of the Karlsruhe Institute of Technology.

Transformation optics use a class of materials called metamaterials that guide and control light.

In their study, Ergin and his colleagues used photonic crystals with a structure that looks like piles of wood to make an invisibility device, or cloak.

They used the cloak to conceal a small bump on a gold surface -- a bit like hiding a small object underneath a carpet and then making both the bump and the carpet invisible.

The "cloak" was composed of special lenses that work by partially bending light waves to suppress the light scattering from the bump.

"This is very exciting, because mankind has always thought about being invisible or having invisibility cloaks," Ergin told the reporters in a telephone interview. "This is the first proof of principle. It shows that the technique works."

He added, however, that it would be many years before anything as large as a person, car or tank could be made to disappear with this technique.

"There have been proposals in the field of transformation optics for different devices like beam concentrators, beam shifters, super antennas which concentrate light into one point from all directions, and much, much more," he said.

"It is really hard to say what the future will bring, but the field is definitely very broad and the possibilities are very large."

德國科學家近日研製出一種通過彎曲光線來隱藏物體的三維“隱形斗篷”。

這項發明爲大型物體隱形鋪平了道路，但研究人員稱，目前他們並不想去猜測可能的應用形式。這一最新研究成果於上週四在《科學》期刊上發表。

德國卡爾斯魯厄理工學院的研究人員托爾加•埃爾金說：“目前，這種隱形斗篷只是光學領域一個‘驚豔’的開始，讓人們知道轉換光學可以做些什麼。”

轉換光學通常使用一種“超材料”來引導和控制光束。

埃爾金及其同事在研究中使用了一種光子晶體來製造隱形斗篷。這種光子晶體的結構看上去像成堆的木頭。

研究人員使用隱形斗篷來掩蓋黃金錶面的一個小凸起，其原理就如同將一個小物體隱藏在地毯下，然後再使這個凸起和地毯都隱形。

這個“斗篷”由特殊透鏡組成，它通過部分彎曲可見光線來抑制凸起發出的光。

埃爾金在接受一個電話採訪時說：“這一發明十分令人激動，因爲人類一直都想隱形或擁有隱形斗篷。這是我們的首個隱形樣本，看來這一技術是可行的。”

但他認爲，利用上述技術使人、汽車、坦克等大型物體隱形尚需時日。

他說：“轉換光學領域曾出現過各種有關光學設備的提議，如波束集中器、波束移位器以及可將來自多個方向的光集中於一點的超級天線等等。”

“很難說將來還會有什麼發明，但轉換光學絕對是個範圍廣、充滿無限可能的領域。”

Vocabulary:

metamaterial：超材料，具有天然材料所不具備的超常物理性質的人工複合結構或複合材料