德国科学家发明3D"隐形斗篷"
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."
德国科学家近日研制出一种通过弯曲光线来隐藏物体的三维“隐形斗篷”。
这项发明为大型物体隐形铺平了道路，但研究人员称，目前他们并不想去猜测可能的应用形式。这一最新研究成果于上周四在《科学》期刊上发表。
德国卡尔斯鲁厄理工学院的研究人员托尔加•埃尔金说：“目前，这种隐形斗篷只是光学领域一个‘惊艳’的开始，让人们知道转换光学可以做些什么。”
转换光学通常使用一种“超材料”来引导和控制光束。
埃尔金及其同事在研究中使用了一种光子晶体来制造隐形斗篷。这种光子晶体的结构看上去像成堆的木头。
研究人员使用隐形斗篷来掩盖黄金表面的一个小凸起，其原理就如同将一个小物体隐藏在地毯下，然后再使这个凸起和地毯都隐形。
这个“斗篷”由特殊透镜组成，它通过部分弯曲可见光线来抑制凸起发出的光。
埃尔金在接受一个电话采访时说：“这一发明十分令人激动，因为人类一直都想隐形或拥有隐形斗篷。这是我们的首个隐形样本，看来这一技术是可行的。”
但他认为，利用上述技术使人、汽车、坦克等大型物体隐形尚需时日。
他说：“转换光学领域曾出现过各种有关光学设备的提议，如波束集中器、波束移位器以及可将来自多个方向的光集中于一点的超级天线等等。”
“很难说将来还会有什么发明，但转换光学绝对是个范围广、充满无限可能的领域。”
Vocabulary:
metamaterial：超材料，具有天然材料所不具备的超常物理性质的人工复合结构或复合材料
