Group items tagged

Cloaking Laser could hide us from "evil aliens "

Metamaterials that absorb seismic waves rather than steer them, might be a better way to protect some buildings, say engineers

what are seismic metamaterials?

must look funny ... They calculate the properties of such a metatmaterial and how it might be constructed with a basic repeating unit in the form of a concrete cylinder some 18 metres in diameter, with four perpendicular holes in its sides (see picture). These cylinders, perhaps varying in size to absorb a range of seismic wavelengths, would need to surround the foundations of a building in cylindrical shells some 60 metres across. That needn't be prohibitively expensive but it would be a big structure that could only be constructed around isolated buildings (thereby somewhat negating the supposed benefit that other buildings in the earthquake 'shadow' might also be protected).

We propose a way of implementing an event cloaking device without the use of metamaterials. Rather than slowing down and speeding up light, we manipulate an obscurity gap by diverting the light through paths of appropriate length with an arrangement of switchable transreflective mirrors.

I forwarded the link to my experimental colleagues and here is the comment from Sergei (the master himself:) "this is what Igor has been doing - an array of plasmonic nanocables. This basically works as a wire-medium slab. All their epsilon and mu are rubbish." * If Sergei is as strict as in this comment, then it IS rubbish. He's not one of the notorious complainer (as e.g. myself.) * Please DO NOT FORWARD this to anybody else, Sergei's comment is NOT FOR PUBLIC USE!

UPDATE: I had a short chat with Sergei and Pekka, Sergei noticed that there is an increasing number of papers on metamaterials, especially in Nature and Science, which are simply wrong, this one being an example. * The idea is based on a very well known effect of wired media. What appears to be interesting about this paper is that they manage to make an optical analogue with aparently low losses. This could be interesting. * The whole interpretation as NIM, "wrong" refraction etc. is total nonsense.

wow, good to know ! But for the privacy you should be aware that this is a public group, so anyone has access to our comments i think !

more transformation optics ... 

I still believe that it is worth to check the thermal, mechanical and chemical properties of the developed metamaterials. For hyperbolic re-entries the radiation is still the dominating heat load source and a dominating bandwith may be indentified. A resistive metamaterial should be placed on the nose cap of the entry body in order to reduce local radiation heat load.

sante can you have a look at this?

anything happening on this since 3 years?

yes it seems like. most of it seems however directed toward understanding this effect, and not toward applications. But i'm still convinced that we could find many very interesting applications !!! a few references from ADS: 1 2011PhRvA..83f3807B 1.000 06/2011 A E X R C U Brida, G.; Chekhova, M. V.; Fornaro, G. A.; Genovese, M.; Lopaeva, E. D.; Berchera, I. Ruo Systematic analysis of signal-to-noise ratio in bipartite ghost imaging with classical and quantum light 2 2011PhRvA..83e3808L 1.000 05/2011 A E R U Liu, Ying-Chuan; Kuang, Le-Man Theoretical scheme of thermal-light many-ghost imaging by Nth-order intensity correlation 3 2011PhRvA..83e1803D 1.000 05/2011 A E R C U Dixon, P. Ben; Howland, Gregory A.; Chan, Kam Wai Clifford; O'Sullivan-Hale, Colin; Rodenburg, Brandon; Hardy, Nicholas D.; Shapiro, Jeffrey H.; Simon, D. S.; Sergienko, A. V.; Boyd, R. W.; Howell, John C. Quantum ghost imaging through turbulence 4 2011SPIE.7961E.160O 1.000 03/2011 A E T Ohuchi, H.; Kondo, Y. Complete erasing of ghost images caused by deeply trapped electrons on computed radiography plates 5 2011ApPhL..98k1115M 1.000 03/2011 A E R U Meyers, Ronald E.; Deacon, Keith S.; Shih, Yanhua Turbulence-free ghost imaging 6 2011ApPhL..98k1102G 1.000 03/2011 A E R C U Gan, Shu; Zhang, Su-Heng; Zhao, Ting; Xiong, Jun; Zhang, Xiangdong; Wang, Kaige Cloaking of a phase object in ghost imaging 7 2011RScI...82b3110Y 1.000 02/2011 A E R U Yang, Hao; Zhao, Baosheng; Qiu

another one ... relevant for Ariadna?

nice paper ... José and Luzi you will like it ...