Make Your Own Invisibility Cloak With a 3D Printer 80
cylonlover writes "Invisibility cloaks have been around in various forms since 2006, when the first cloak based on optical metamaterials was demonstrated. The design of cloaking devices has come a long way in the past seven years, as illustrated by a simple, yet highly effective, radar cloak developed by Duke University Professor Yaroslav Urzhumov, that can be made using a hobby-level 3D printer."
Re:Doesn't abscense imply presence? (Score:4, Informative)
Though I think with this cloak, you wouldn't know specifically where it is. Radio waves warping around it would be received but not in the correct location unless you projected a grid of frequencies directly at it and then watched what geometric pattern they were received in then reversed it. You wouldn't know the object's exact location otherwise. Any cloak that simply makes the radar waves disappear though would show up easily. I believe this one does wrap the waves around though, instead of just absorbing them, just they wouldn't arrive quite correctly aligned on the other side the way they would if there was no object there so like I said, a grid would tell you the radar waves are being bent by something.
Re:Doesn't abscense imply presence? (Score:5, Informative)
Read up on how they work ;-)
In short, no, they're not like blackholes.
The principle behind them is that emmissons heading into the cloak are routed around the object and then leave, and here's the clever bit, in a direction and intensity equal to what would happen if the invisible object wasn't there.
A drawback of this is, if you were building your cloak on the observable spectrum, if your inside the cloak you can't see anything outside of it (as all the incoming light gets diverted around you)! Admittedly it's only a draw back if looking around you is important, there's good reasons not to care and cool applications e.g. building a sea platform that is invisible to incoming waves (google it, my brain hurts from remembering so much already)