New York scientists unveil 'invisibility cloak'

Ron Czapala

http://news.yahoo.com/york-scientists-unveil-invisibility-cloak-rival-harry-potters-014359862.html

Scientists at the University of Rochester have discovered a way to hide large objects from sight using inexpensive and readily available lenses, a technology that seems to have sprung from the pages of J.K. Rowling's Harry Potter fantasy series.

Cloaking is the process by which an object becomes hidden from view, while everything else around the cloaked object appears undisturbed.

Electrodude

It's just a bunch of lenses. It's not any real cloaking device. If you block the focal point or any rays going through the focal point, it doesn't work. If you put your hand next to the focal point, you can pretend your hand is invisible when, in reality, the rays of light are all focused through one point that your hand isn't blocking.

Ray diagram:

  ^     ^    ^     ^
--|     |----|     |--
  |\   /|    |\   /|
  | \ / |    | \ / |
--|--+--|----|--+--|--
  | / \ |    | /H\ |
  |/   \|    |/ H \|
--|     |----|  H  |--
  v     v    v  H  v

-\/+: light rays
^|v : lens
H   : "invisible" hand

EDIT: ray diagram is slightly off - one focal point is inside one of the lenses, but it's close enough and it can't really be made any better with ASCII art

ValeT

I wish real cloaking was that easy....

ganzuul

There was talk a few years ago about meta-material cloaks which work in RF. The narrative went that the material could become useful one day as they shrink feature sizes to the optical range... but RF cloaking as they showed it could be useful against radar.

Tubular

So a cloaking a donut (with a hole for the rays to pass through) would be a good test case?

Dave Hein

I've been seeing this the past few days on the internet and I thought it was a hoax. Everybody knows that this can be done with lenses, don't they? Isn't it just common knowledge? How could anybody possibly patent this idea? The first telescope I had as a kid focused the beam though a plastic collimator with a small hole in the center. The lenses in the telescope made the collimator "invisible". I discovered the collimator when I tried to use my telescope as a projector during a partial solar eclipse and melted the plastic collimator to the point where the hole closed up. I had to remove it to get my telescope working again.

Electrodude

Tubular wrote: »

So a cloaking a donut (with a hole for the rays to pass through) would be a good test case?

That's the only use I could think of for it. But that still leaves the major problem that anyone can see whatever you're trying to hide by just flying over it...