Posted on 06/11/2011 3:06:20 AM PDT by LibWhacker
With a new printing technique, researchers can now make enough metamaterials to begin fabricating invisibility cloaks and superlenses.
A new printing method makes it possible to produce large sheets of metamaterials, a new class of materials designed to interact with light in ways no natural materials can. For several years, researchers working on these materials have promised invisibility cloaks, ultrahigh-resolution "superlenses," and other exotic optical devices straight from the pages of science fiction. But the materials were confined to small lab demonstrations because there was no way to make them in large enough quantities to demonstrate a practical device.
"Everyone has, perhaps conveniently, been in the position of not being able to make enough [metamaterial] to do anything with it," says John Rogers, a professor of materials science and engineering at the University of Illinois at Urbana-Champaign, who developed the new printing method. Metamaterials that interact with visible light have previously not been made in pieces larger than hundreds of micrometers.
Metamaterials are made up of intricately patterned layers, often of metals. The patterns must be on the same scale as the wavelength of the light they're designed to interact with. In the case of visible and near-infrared light, this means features on the nanoscale. Researchers have been making these materials with such time-consuming methods as electron-beam lithography.
Rogers has developed a stamp-based printing method for generating large pieces of one of the most promising types of metamaterial, which can make near-infrared light bend the "wrong" way when it passes through. Materials with this so-called negative index of refraction are particularly promising for making superlenses, night-vision invisibility cloaks, and sophisticated waveguides for telecommunications.
The Illinois group starts by molding a hard plastic stamp that's covered with a raised fishnet pattern. The stamp is then placed in an evaporation chamber and coated with a sacrificial layer, followed by alternating layers of the metamaterial ingredients—silver and magnesium fluoride—to form a layered mesh on the stamp. The stamp is then placed on a sheet of glass or flexible plastic and the sacrificial layer is etched away, transferring the patterned metal to the surface. So far Rogers says he's made metamaterial sheets a few inches per side, but by using more than one stamp he expects to increase that to square feet. And, he says, the stamped materials actually have better optical properties than metamaterials made using traditional methods.
"We can now bang out gigantic sheets of this stuff," Rogers says. Making the mold for the stamp takes care, but once that mold has been created, it doesn't take long to make many reusable stamps.
Xiang Zhang, chair of mechanical engineering at the University of California, Berkeley, says this work represents an important step toward applications for optical metamaterials. "Various metamaterials could be made bigger by this method," says Zhang, who in 2008 created the design that Rogers used for this first demonstration. "For example, macroscale 2-D lenses and cloaks may be possible, and possibly solar concentrators, too." One potential application is in lenses that integrate multiple functions in single devices, for telecommunications and imaging.
"This printing technique is quite powerful and has the potential to scale to very large areas," says Nicholas Fang, an associate professor of mechanical engineering at MIT. Fang says this type of metamaterial would be particularly interesting for infrared imaging devices.
Been there done that.
Ask any motorcycle rider about being invisible.
For some reason people are absolutely blind to anyone near them that is on a bike.
I swear if I had a full sized decal of a person on a motorcycle on the side of my big rig truck I would have a dozen cars running into me each and every day.
You’re right. They always say “I didn’t see it.”. I knew personally a guy who was killed because a woman driver didn’t see him.
The judge should take those drivers off the road by revoking their licenses.
And the Air Force swoops in to black-project this research in 3,2,1...
That was me.
In May of 1967 (day after memorial Day) I was broadsided on my way to work by a car who 'didn't see me'. I was on a Main Street, had the right of way, and wasn't speeding -- them BAM! This guy blew through from a side street.
I went flying, about 20 feet in the air, with my right ankle and some foot bones smashed, and my helmet scratched to hell from the landing (it kept me alive). I still have a 2½" screw through my ankle which was needed to hold all the little bones together. It seems like I was in a cast forever.
(if I slightly bump it, it still hurts like hell. Cowboy boots help prevent that)
I think scientists should work on something that creates an image that people WILL see. Be it from a small holo projector or some form of outerwear that has a device that triggers a mental stimuli.
I own two bikes, but instead of installing super bright high beams on them I use those obnoxious blue HID lamp kits.
Another thing that helps is to have an antenna on your bike. make it look as if your bike from a distance may be a Highway Patrol bike, I even have a project that flashes a couple of red lasers hidden in my tailights that for a micro second flashes very brightly at a person behind me.
I think the real trick to Mark 1 invisibility is an optical light frequency that actually turns off the brain, much like some Japanese cartoon flashing lights.
“Xiang Zhang, chair of mechanical engineering at the University of California, Berkeley, says this work represents an important step toward applications for optical metamaterials.”
You can already bet that the Chi-Coms are getting all the details on how to make metamaterials, too!
if I had a full sized decal of a person on a motorcycle on the side of my big rig truck I would have a dozen cars running into me each and every day.
Now tell the truth - do YOU see motorcycles as well as you see big rigs?
I got a riding-like-a-maniac ticket, and in motorcycle traffic school, the instructor told the “class” that people have “look for cars” drummed so deeply into their heads that they don’t see other vehicles, including motorcycles, trucks, and semi tractor trailers.
His exact quote, “They are looking for cars. C-A-R-S, cars. If you are not a car, they do not see you.”
That was in 1977; I’ll never forget it.
I drive a concrete mixer for my wages and I have two motorcycles I spend those wages on so I live in both worlds.
Use spies on Romulus to steal the technology.
Motorcycles are difficult to see. The car I was driving was hit by a motorcycle. He came from my right, and I didn’t see him until he was inches from the car. It was his fault, it was a young kid driving recklessly, but still, it freaked me out that I did not see him.
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