(糖心视频Org.com) -- "Many groups have been working devices that make objects invisible," Che Ting Chan tells 糖心视频Org.com. 鈥淢ost of these devices, however, encompass the object to be cloaked.鈥� Chan, a scientist at The Hong Kong University of Science and Technology, believes that it is possible to create a cloaking device that would be able to render an object invisible without encompassing it.
鈥淲ith the devices that encompass the object,鈥� Chan continues, 鈥渢he cloaked subject is 鈥榖lind鈥�. It can鈥檛 鈥榮ee鈥� out through the cloak. We can鈥檛 see the object, but the object can鈥檛 see us, either. We wanted to create a conceptual design that would let the object 鈥榮ee鈥� out through the cloak while hiding it from sight.鈥� Along with Yun Lai, Huanyang Chen and Zhao-Qing Zhang, Chan believes that this could be accomplished. Their ideas are published in 糖心视频ical Review Letters: 鈥�Complementary Media Invisibility Cloak that Cloaks Objects at a Distance Outside the Cloaking Shell.鈥�
Right now, such a device exists only theory. 鈥淲e haven鈥檛 built the device,鈥� Chan says, 鈥渂ut we have shown mathematically how it could work. It is a very specific description of the materials needed. If you have the time and resources, we think it could be done.鈥� He points out that it might have interesting possibilities in a number of fields where invisibility might be desirable.
Theoretically, a device such as Chan suggests, would work through complementary media. 鈥淥ur strategy is to put the cloaking device and the object to be cloak next to each other. The cloaking device is a kind of anti-object. The way the light is gathered and scattered by the two objects - the cloaking device and the object it is making invisible - would cancel each other out.鈥� Chan continues by explaining that the cloaking device would become invisible as well. 鈥淏oth must be invisible in order for this to be effective, and I think we have shown in theory how this could work.鈥�
Chan admits that 100 percent invisibility is only available for one wavelength, however. 鈥淩ight now, the usefulness, especially for military applications, is limited,鈥� he says. 鈥淵ou can only make the object invisible in one wavelength, so if I made it invisible for the visible spectrum, all someone would have to do is use radar to detect the object. A lot of work would need to be done to make a cloaking device that worked for more wavelengths.鈥� He pauses, before adding, 鈥淚t might be possible to make the object almost invisible for broader wavelengths, but that would also take a lot of work. And you still wouldn鈥檛 have 100 percent visibility.鈥�
The Hong Kong team, although interested in rendering objects invisible, is working on another ambitious project. 鈥淲e have shown that we can cause invisibility in objects, and allow them to 鈥榮ee鈥� out of the cloak,鈥� he says. 鈥淲e are now working on how to transform how an object looks. Invisibility was just the first step in this. By understanding how complementary media invisibility might work, we can also look at how it might be possible to transform the look of an object into something else. Perhaps make an apple look like a banana.鈥�
Science is beginning to sound more like magic by the day.
More information: Yun Lai, Huanyang Chen, Zhao-Qing Zhang, and C. T. Chan, 鈥淐omplementary Media Invisibility Cloak that Cloaks Objects at a Distance Outside the Cloaking Shell.鈥� 糖心视频ical Review Letters (2009). Available online: .
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