InvisibilityCloak
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Researchers create an acoustic cloaking device that works underwater
The concept of a cloaking device has a lot of appeal and though we're far from being able to make 3D objects invisible to the human eye, researchers continue to develop new ways in which to shield objects from other sorts of detection. At the Meeting of the Acoustical Society of America taking place this week in Minnesota, Penn State University researchers described a design they've developed that allowed a 3-foot-tall pyramid made from perforated steel plates to deflect sound waves in a way that could make it invisible to instruments like sonar.
Invisibility 'cloak' hides objects by making them seem flat
Humanity is still some distance away from a real, honest-to-goodness invisibility cloak, but British scientists are that much closer to making it practical. They've developed a coating that uses graded refractive index nanocomposite materials (just rolls off the tongue, really) to reduce an object's electromagnetic signature. Ultimately, it makes curved surfaces seem flat -- electromagnetic waves leave almost as if there were no object at all.
High-speed camera tracks light at 100 billion fps
For most of us, high-speed image capture, say 120 or 240 frames per second, is enough to get a good look at stuff happening in the blink of an eye -- like a water droplet hitting the ground or a Bichon Frisé snagging his favorite ball. For faster subjects, industrial-strength high-speed cameras can grab tens of thousands of frames per second (or more). But when your rapidly moving target is light itself, you're going to need something a bit quicker -- to the tune of 100 billion fps, according to Nature.
Mischief managed: researchers produce an invisibility cloak in just 15 minutes
Grab your Marauder's Map and get ready to roll. Researchers at Zhejiang University in China have pioneered a new, time-efficient method of producing real world invisibility cloaks made out of Teflon. While it isn't the first time we've come across an invisibility cloak, it is the first to make use of an innovation called topology optimization. Thus far, physicists working on invisibility have largely relied on metamaterials -- synthetic materials that alter the behavior of light as it interacts with objects -- but the cost and difficulty of manufacturing them has made them an impractical option. The Zhejiang team has circumvented those obstacles by creating a so-called "eyelid" out of Teflon, the computer-altered topology of which minimizes the distortion of light as it moves past a cloaked object -- and it only took 15 minutes to produce. Since the Teflon eyelid is only invisible to microwaves, it won't enable you to roam the halls of Hogwarts unseen, but the technology could potentially open up new avenues in exploring invisibility on other wavelengths. To learn more, read the full paper at the source link below.
Alt-week 6.15.13: Chris Hadfield's retirement, invisibility cloaks and dino-bird feathers
Alt-week takes a look at the best science and alternative tech stories from the last seven days. What goes up must eventually come down, and shortly after landing on Terra Firma from his last of three ISS missions, Chris Hadfield has resigned from the Canadian Space Agency. That leaves us to wax poetic on his legacy of space education and other oddities, while we also make goldfish disappear and admire dinosaur plumage. Welcome to alt-week.
Don't mind the zero-emissions Mercedes fuel-cell car behind the invisible curtain (eyes-on video)
Mercedes wanted to make a dramatic statement about how its new B-Class F-Cell car passes through the environment without leaving a trace, so it placed it behind an invisible LED curtain. We wanted to (not?) see that for ourselves at the Paris Auto Show, so took a quick tour of the magic LED cloak and the technology behind it. It doesn't work quite as well in a show hall as it did when we first saw it in its natural habitat, but the system was still a fun way to show off Merc's green ambitions. It works by passing video from behind the car taken with a Sony video camera through a laptop to a 200 x 300 resolution LED curtain. That makes the car blend in with its background, which is what such a car would do in the real world as far as its emissions go -- apart from a little water, of course. See the video below for the complete technical explanation.
Scientists use metal and silicon to create invisibility cloak (no, you can't wear it)
In the quest to achieve that much-desired invisibility cloak, scientists have redirected light, used heat monitoring and even gone underwater -- with varying degrees of success. The latest attempt at this optical illusion is from engineers at Stanford and the University of Pennsylvania, who have developed a device that can detect light without being seen itself. When the ratio of metal to silicon is just right, the light reflected from the two materials is completely canceled out. The process, called plasmonic cloaking, controls the flow of light to create optical and electronic functions while leaving nothing for the eye to see. Scientists envision this tech being used in cameras -- plasmonic cloaking could reduce blur by minimizing the cross-talk between pixels. Other applications include solar cells, sensors and solid-state lighting -- human usage is conspicuously absent on that list.
Researchers working on thermal cloak, Predators trill their disapproval
Slathering yourself with mud to avoid head-hunting aliens is great and all, but it ain't exactly the paragon of good personal hygiene. Fortunately, researchers have concocted a cleaner and less cakey defense against Predators that's more likely to be mom approved. Fresh on the heels of the microwave invisibility project at the University of Texas at Austin, French researchers have found a way to make a cloak that can hide a subject from thermal imaging devices. The concept uses alternating materials with varying rates of diffusion to move heat around and create a thermally invisible region. Conversely, the technique can be used to concentrate heat in one spot so it gets hot rapidly. Although it doesn't quite have the wow factor of Cornell's invisibility project, the thermal research may prove to be more practical because it also can be used to manage heat and improve cooling in components such as computer chips. Of course, the question now is, can it be used to cloak an entire tank?
Cornell scientists perform optical illusion, herald invisibility through bending of light (video)
Taken at face value, you'd almost think that Cornell scientists had successfully bent the fabric of time. With gobs of fiber optics at their disposal, the researchers have devised a method to distort light in a way that makes events in time undetectable to observers. Initial success in this Pentagon-backed invisibility project has cloaked an event for 40 trillionths of a second, leading Cornell scientists to tout, "You kind of create a hole in time where an event takes place. You just don't know that anything ever happened." The feat is performed by separating light into more fundamental wavelengths, first by slowing the red and speeding the blue. A resultant gap forms in the beam, which leaves a small window for subterfuge. Then, as the light passes through another set of fibers -- which slow the blue and speed the red -- light reaches the observer as if no disturbance had taken place at all. While the brilliant researchers ultimately imagine art thieves being able to pass undetected through museums with this method, the immediate challenge will be in prolonging the light gap. This could prove frustrating, however, due to the scattering and dispersion effects of light. As Cornell scientists dream of their ultimate heist, visual learners will most certainly want to check the video after the break.
Invisibility cloak made of carbon nanotubes uses 'mirage effect' to disappear
If the phrase "I solemnly swear I'm up to no good" means anything to you, you'll be happy to know that scientists have come one step closer to a Potter-style "invisibility cloak" so you can use your Marauder's Map to the fullest. With the help of carbon nanotubes, researchers have been able to make objects seem to magically vanish by using the same principle that causes mirages. As anyone who's been especially parched along Route 66 knows, optical illusions occur when heat changes the air's temperature and density, something that forces light to "bend," making us see all sorts of crazy things. Apply the same theory under water using nanotubes -- one molecule carbon coils with super high heat conductivity -- and scientists can make a sheet of the stuff "disappear." Remember, it only works underwater, so get your gillyweed ready and check out the video after the break.
BAE's infrared invisibility cloak makes tanks cold as ice, warm as cows
Warfare's constantly evolving. Daylight battles became late-night duels, and pre-noon skirmishes shifted to sundown slaughters -- some might say we're just getting lazy, but either way, thermal imaging now plays quite the vital role. Now BAE and the FMV -- Sweden's equivalent to DARPA -- have a way to mask the heat signature of heavy machinery. Adaptiv is a wall of 14 centimeter panels that monitor the ambient heat and match it, so it can't be picked out from the background radiation. The tech can also be used to replicate the profiles of other things -- you know, like a spotted calf or a Fiat 500. BAE believes the tech is scaleable for buildings and warships, the only downside being that all future commanders will have to make sure their operations are finished before dawn. Wouldn't want your soldiers to see that five o'clock (AM) shadow, now would we? [Thanks, Rob]
Duke University's underwater invisibility cloak stills troubled waters
Everyone's jumping on the invisibility cloaking bandwagon these days, but no one's quite managed to fully deliver on the promise. The same goes for two Duke University researchers who believe their mesh casing could grant the gift of concealment to underwater craft -- submarines, anyone? According to the proposed model, a specially designed shell punctuated by complex patterns of permeability and millimeter-sized pumps would eliminate the drag and turbulent wake caused by an object as it moves through the water. Utilizing the penetrable gaps in the case, water would at first accelerate, and then decelerate to its original speed before exiting -- rendering the fluid around the object virtually undisturbed. Now for the bad news: the design doesn't quite work for large-scale, real-world implementations -- hello again, submarines -- since the tech can only cloak small structures, like "a vehicle one centimetre across... [moving] at speeds of less than one centimetre per second." It's a massive bummer, we know, but we're getting there folks -- you just won't see it when it actually happens.
Duke University physicists test first air-based acoustic invisibility cloak
Firmly departing from the Stuff Of Dreams category, Duke University physicists have successfully tested an acoustic cloaking device that fools sound waves while looking nowhere near as scifi as you'd think. Layering nothing more than a bunch of hole-punched plastic sheets -- known as meta-materials, for those curious -- atop a ten centimeter long block of wood, highly-directed sound in the 1 - 4kHz range bounced right off the concealed object none the wiser. The cloaking tech owes some of its origin to the math behind transformation optics -- and maybe to the Duke team, too. Besides allowing defense department bunkers to erupt into silent applause, the research should prove useful in the construction of future concert halls. DIY hobbyists, let us know what you can rig up with some trash bags. [Thanks, Drew]
Metamaterial printing method inches us closer to invisibility cloaks
In theory, metamaterials are all kinds of awesome -- they can boost antenna strength, focus lasers, and create invisibility cloaks. But, they've been limited to day dreams lab experiments because producing the light-interfering materials in any practical quantity has been difficult and time consuming. John Rogers, a professor at the University of Illinois has figured out a way to print a layered, nano-scale mesh that bends near-infrared light in much larger amounts than previously possible. The new method, based around a plastic stamp, has been used to create sheets of metamaterial measuring a few square inches, but Rogers is confident he can scale it up to several feet. Who knows, by the time the second installment of The Deathly Hallows hits theaters in July you could get the best Harry Potter costume -- one that lets you sneak in without shelling out $13. [Thanks, Plum G.]
Inhabitat's Week in Green: sugar-covered lamps, IKEA's solar lamp, and the 30MPH all-wood racing bike
Each week our friends at Inhabitat recap the week's most interesting green developments and clean tech news for us -- it's the Week in Green. Several breakthroughs sent shock waves through the field of renewable energy this week as Inhabitat reported on a new type of "invisibility cloak" that could supercharge solar cells and researchers at MIT harnessed viruses to improve the efficiency of dye-solar cells by a full third. We also cast a keen eye on the royal wedding, which is expected to produce 6,765 tons of CO2, and we explored a new wireless charging technology being developed by Toyota and WiTricity. And if futuristic eco cities float your boat, check out this self-sustaining ecotopia designed to produce energy and food in the North Sea. We also showcased several novel electric vehicles, including the crazy Uno 3 transforming scooter which is now available for pre-order. Alternative fuels also took off as a Kentucky man unveiled a car that runs on bourbon and a mobile greenhouse powered by renewable energy hit the streets of New York City. And from the realm of pedal-powered transportation we brought you the SplinterBike - a bicycle made entirely from wood that can hit a record-breaking 30 miles per hour. In other news, energy-efficient lighting advanced by leaps and bounds this week as we flipped the switch on IKEA's new solar-powered Solvinden lamp and we spotted a crystalline "Stardust" LED lamp made from sugar at the Milan Furniture Fair. Finally, we shined a spotlight on Katy Perry's debut on American Idol as a LED-studded Extraterrestrial, and we took an exclusive look inside New York City's first LEED gold skyscraper - the Hearst Tower!
Flexible metamaterial could make your next invisibility cloak rather more comfortable
Metamaterials have a lot of potential future applications, but only one of them really gets our geeky senses tingling: invisibility cloaks. Previous theoretical examples we've seen were built upon rigid silicon substrates, meaning they'd be about as comfortable to wear as a motherboard jacket with ISA sleeves. But, a new material at the University of St. Andrews has been created that offers similar light-bending properties in a flexible package, crafted by the formation of a membrane upon a release layer, etching microscopic gold bars upon it, and then removing the release layer to have just the blingy membrane left behind. It can be tuned to bend various wavelengths, with the team having success working at wavelengths as short as 620nm -- you know, red. If there's one problem it's the size of the thing, with current prototypes measuring just 5 x 8mm, but it is said to be "scalable to industrial levels," meaning next-year's Harry Potter costume could be the best one ever.
Invisibility cloak upgraded to bend infrared light, not to mention our minds
The fabled cloak of invisibility was once considered impossible for modern science, chilling out with perpetual motion up in the clouds, but these days scientists are tilting at blurry windmills with a modicum of success several times a year. The latest advance in theory comes to us from Michigan Tech, which says it can now cloak objects in the infrared spectrum. Previous attempts using metallic metamaterials could only bend microwave radiation, the study claims, but using tiny resonators made of chalcogenide glass arranged in spokes around the object (see diagram at left) researcher Elena Semouchkina and colleagues successfully hid a simulated metal cylinder from 3.5 terahertz waves. While it's hard to say when we might see similar solutions for visible light, even a practical application of infrared cloaking could put your night vision goggles to shame, or perhaps block covert objects from being detected by those newfangled terahertz x-rays.
3D invisibility cloak fashioned out of metamaterials
Those HDTV manufacturers did tell us that 3D was going to be everywhere this year, didn't they? Keeping up with the times, scientists investigating potential methods for rendering physical objects invisible to the human eye have now moved to the full three-dimensional realm. The Karlsruhe Institute of Technology has developed a photonic metamaterial that can make things disappear when viewed from all angles, advancing from previous light refraction methods that only worked in 2D. It sounds similar to what Berkeley researchers developed not too long ago, and just like Berkeley's findings, this is a method that's still at a very early stage of development and can only cover one micrometer-tall bumps. Theoretically unlimited, the so-called carpet cloak could eventually be expanded to "hide a house," but then who's to say we'll even be living in houses by that time?
Video: simulated 'quiet zone' cloaking hides an object in 2-D
You don't have to be able to pick a Romulan out of a crowd of Vulcans to be intrigued by the idea of cloaking, and indeed many non-trekkers have tried to hide things in plain sight using electromagnetism, acoustic superlenses, or light-bending materials. The latest attempt relies on devices that emit cancelling waves of the sort anyone who's ever seen a Bose commercial should quite familiar with, combining to negate any external, incoming waves. What's different here is that they also recombine on the other side of the object being cloaked, as shown in the video below, meaning that incoming surge is then re-generated and continues on undisturbed -- potentially even reflecting back through the object again should it hit something on the far side. It's part of research at the University of Utah and, for now, only works in a theoretical two-dimensional world where triangles and squares are ruled by pentagons, hexagons, and priestly polygons. Optical camouflage is sadly not believed to be possible using this technique, but sonar and radar are likely implementations, as well as mechanisms to subvert earthquakes, tsunamis, and maybe even neighboring speed metal fans.
Electromagnetic invisibility a precursor to the real thing?
This could either be that one giant leap, or just another in a long sequence of multidirectional small steps on the Quixotic quest for undetectability. So-called dc metamaterials are the chief culprit for inciting our interest anew, as researchers from Universitat Autònoma de Barcelona have found a way to use them to render metallic objects invisible to low frequency electromagnetic waves. Composed of irregular networks of superconductors, the metamaterials are capable of granting superpowers altering the magnetic field of materials, and in theory, this advance could aid magnetic imaging in medical settings and also help cloak military vessels from magnetic detection. Of course, there's still the whole "oh, now we need a working prototype" conundrum, but hey, at least we've got the gears turning in the right direction.[Via PhysOrg]
