Glass Invisibility Cloak Shields Infrared 115
An anonymous reader writes with the latest advance in the quest for a cloak of invisibility (Michigan Tech University's press release). We've been following this research as it develops; here are stories from each of the last four years. "Invisibility cloaks are slowly working their way up to shorter wavelengths — starting at millimeter-long microwaves and working their way to the nanometer wavelengths of visible light. EETimes says we are about half way there — micrometer wavelengths — in this story about using chalcogenide glass to create invisibility cloaks in the infrared. Quoting: 'Invisibility cloaks cast in chalcogenide glass can render objects invisible to infrared frequencies of light, according to researchers at Michigan Technological University... Most other demonstrations of invisibility cloaks have used metamaterials composed of free-space split-ring resonators that were constructed from metal printed-circuit board traces surrounded by traditional dielectric material. The Michigan Tech researchers... claim that by substituting nonmetallic glass resonators made from chalcogenide glass, infrared cloaks are possible too...'"
Sigh, no (Score:5, Informative)
Calling these things "invisibility cloaks" is being very, very generous.
They are fundamentally flawed in the specs: percent transmission, angle, bandwidth, and refraction.
They're more of a laboratory curiosity than anything that would fool anybody.
Re:"halfway there" on a logarithmic scale (Score:3, Informative)
Yes. On a linear scale, we're basically all the way there. So what's you're point?
Seriously, log scales are the better way to measure this sort of thing, not just for convenience. Look at Moore's law.
On the other hand, I'm confused as to why we're only halfway there. Light wavelenghts aren't nanometer in size, they're hundreds of nanometers. Which means that we've gone from 1E-3 m to 1E-6 on our way to 1E-7. In log space, we're 75% of the way there.
Finally! (Score:1, Informative)
When the Predators invade, we'll be ready!
Re:Wait...does this mean (Score:3, Informative)
You're talking about thermal imaging. That's not how IR used for night-vision works. Your IR remote control doesn't shoot a jet of warmth at the TV. It's just a spectrum of light slightly outside of what we see.
Actual IR cameras work so well for finding people because of what's REFLECTING the IR light. Synthetic materials reflect differently to the sorts of things you find in the wild. Additionally IR is useful for marking friendlies in such a way that people without IR gear can't see.
Modern night-vision goggles use a combination of low-light sensitive cameras, IR imagery and image processing to enhance the image. I'm not actually sure if you'll find thermal imaging in use at all for combat situations.
Keeping that in mind, because the images are often of such low quality the concept of bending light around an object- even with large distortion errors - works very well. You're merely adapting the entire cloak to suit the surrounds, which is exactly what modern techniques for hiding from IR cams involves, except you disguise yourself with the surrounding foliage/debris/whatever. Same materials, same colour, same IR reflectivity. Fooling our eyes in daylight is going to be a little harder.
Re:Headline parsing (Score:3, Informative)
Re:Military (Score:3, Informative)
I thought mosquitoes found animals by the carbon dioxide they breath out...
Re:not really (Score:3, Informative)
measure the surrounding background heat levels and *match them*, like a chameleon matches background visual colors
How invisibility cloaks work http://www.howstuffworks.com/invisibility-cloak.htm [howstuffworks.com]
what's that again? (Score:4, Informative)
Re:Does this mean I can hide in an oven? (Score:3, Informative)
Imagine a smoothly-flowing stream: If you put a rock in it, the flow will be disturbed. If the rock is irregularly shaped, some of the water will "bounce" back(because this is water, and not photons, it will only cause some turbulence, not actually be reflected; but such is the weakness of analogies...). If the rock has a nice, smooth, hydrodynamic sort of shape, the water will part smoothly when it hits the rock and then come back together behind the rock, with minimal disruption to the flow. The rock exists; but for a hypothetical organism that can only detect water currents(say a water bug with sensory hairs, sitting downstream), it will be invisible.
It turns out that, on small scales, under laboratory conditions(and often only in two dimensions), with exotic materials, you can cause photons to "bend around" an object, thus rendering the object effectively invisible. They don't get absorbed, so you can't detect the object by their absence, and they don't get reflected, so you can't see the object, they just take a circuitous path around the object, and continue on their merry way as though nothing was there(though, since a semicircular path is slightly longer than the straight path would have been, I suppose a sufficiently sensitive travel-time comparison system could still detect the cloaked object...)