

Paraxial ray optics cloaking - mhb
https://www.osapublishing.org/oe/fulltext.cfm?uri=oe-22-24-29465&id=304785

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thebooktocome
Disappointing that they don't cite the work of the of Greenleaf, Kurylev,
Lassas and Uhlmann:
[http://www.rni.helsinki.fi/~mjl/invisibility_publications.ht...](http://www.rni.helsinki.fi/~mjl/invisibility_publications.html)

They were the first to do conformal cloaking, which was later publicized in an
article in Nature circa 2008 that also failed to cite their work.

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mhb
Video:
[https://www.youtube.com/watch?v=vtKBzwKfP8E](https://www.youtube.com/watch?v=vtKBzwKfP8E)

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jasmcole
There is really nothing physically interesting in this - a two lens telescope
(in the geometric optics approximation) admits a point where rays from the
object are focussed. It's not surprising then that there are regions in
between which are unable to propagate rays to the collection optic.

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Mithaldu
I wonder if this could be used to make traffic corners slightly less
dangerous. If it could be scaled up enough, you could maybe put a tube
diagonally through a hedge, with a big viewing assembly on one end.

Otherwise, i'm a bit at a loss as to possible uses of this.

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tizzdogg
In this setup it looks like you can't obscure the center of the cylinder
defined by the lenses. That's where the background light goes. So the cloaked
region is actually a long tube with a hole through the middle, and probably
wouldn't work for street corners. It's a neat demonstration though. It seems
like the point is to show cloaking with the simplest materials and optics
possible.

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Mithaldu
> the cloaked region is actually a long tube with a hole through the middle

Exactly, and if you can make that hole small enough and long enough with the
viewport being large enough, you could use this to tunnel view through static
large structures that aren't bothered by small tunnels through them.

