A Step Towards an Invisibility Cloak

An anonymous reader alerts us to work out of Purdue University in Indiana, where researchers have produced a design for a method of cloaking objects of any shape and size at a single wavelength of visible light. The math for such an invisibility effect was worked out last year at Duke and in the UK, but the new work, to be published in Nature Photonics this month, is the first practical design. The lead researcher, Vladimir Shalaev, notes that even though the current design works only at a single wavelength, and so would not convey true invisibility, it could still be useful — against, for example, night-vision goggles or laser target designators. Shalaev calls the technical challenge of producing an all-wavelengths cloak "doable in principle."

Re:Invisible to lasers, anyway.

[Opportunist]

Weapons-grade lasers (i.e. lasers that do damage themselves) are with todays technology not really an issue. To create damage comparable to conventional methods of kaboom, you'd have to haul around a LOT more material and those pieces also tend to be a LOT more expensive. War is a cost/gain game, so don't expect to see any laser weapons too soon on the battlefields of the world.

What this aims at is laser targeting systems. Those lasers carry hardly enough firepower to cause any damage (ok, should you look RIGHT into them, maybe you might have some problem), but they point out the target to a laser guided weapon. And, well, you can't hit what you can't see (unless you decide to fire a spray of those kickass expensive laser guided weapons, which has not really a good cost/gain relation).

Re:Invisible to lasers, anyway.

[YGingras]

Except that night vision devices aren't restricted to a single wavelength. Night goggles only amplify the light in the whole spectrum. The whole thing, not a single wavelength. The output is converted to monochrome to stimulate the more sensitive rod cells. By limiting color output the pupil stays more dilated and can gather more light. Its the same thing with astronomical telescopes. You read your maps with a red light and you get eyes pieces with exit pupil [wikipedia.org] matching your night time pupil diameter.

Lightbending 101

[__aawkdb2598]

This innovation and others like it have seen far too much press already. I know, I know, it's slashdot and no one RTFA anyway, but if you did you'd quickly realize that there really is nothing to see here. Let me explain at least for those of you who will read a comment if not any of the articles appearing in popular science sources for the last several months:

Imagine for the moment placing an object behind a mirror. Better yet, inside a mirror. Amazing! You cloaked it from observation from visible wavelengths! Understood, this is much more meta and complex than all that. It bends the light around instead of sending it away. But that's all. In the same way that you can't see anything on the other side of the mirror, nothing on the other side of the mirror can see you. We're not going to see invisibility cloaks or special forces in lightbending armor out of this, because even if the technology were practical and cheap the special forces would still be blind. Any light you let in is light that's not making you invisible by being elsewhere.
These results are undeniably groundbreaking, but they are received as something entirely different from what they really are.