Awful pun in the title, sorry! So here is the news. Scientists at Rochester have invented – well, not quite invented, but significantly improved over old versions – a device which works as an invisibility cloak. The new approach not only results in better concealment of the object, but can also use cheaper materials. In fact, you can even make your own using 4 lenses! Read the full article (from which I took the Rochester cloak building instructions and the image below) here. If you or your university has a subscription to the OpticsInfoBase journal, you can read the mathematical basis of the cloak. I love the title of the paper. I bet they enjoyed writing it.
J. C. Howell, J. B. Howell, and J. S. Choi, “Amplitude-only, passive, broadband, optical spatial cloaking of very large objects,” Appl. Opt. 53, 1958-1963 (2014), URL: http://www.opticsinfobase.org/ao/abstract.cfm?URI=ao-53-9-1958
- Purchase 2 sets of 2 lenses with different focal lengths f1 and f2 (4 lenses total, 2 with f1 focal length, and 2 with f2 focal length)
- Separate the first 2 lenses by the sum of their focal lengths (So f1 lens is the first lens, f2 is the 2nd lens, and they are separated by t1= f1+f2).
- Do the same in Step 2 for the other two lenses.
- Separate the two sets by t2=2 f2 (f1+ f2) / (f1— f2) apart, so that the two f2 lenses are t2 apart.
Earlier this year, scientists from the University of Central Florida made the news with the first large-scale invisibility cloaking device. Here is their paper in Advanced Optical Materials:
Li Gao, Youngmin Kim, Abraham Vazquez-Guardado, Kazuki Shigeta, Steven Hartanto, Daniel Franklin, Christopher J. Progler, Gregory R. Bogart, John A. Rogers, and Debashis Chanda, Negative Index Materials: Materials Selections and Growth Conditions for Large-Area, Multilayered, Visible Negative Index Metamaterials Formed by Nanotransfer Printing (Advanced Optical Materials 3/2014)http://onlinelibrary.wiley.com/doi/10.1002/adom.201470019/abstract