Finding The Invisible In The Visible

A team of scientists at the Massachusetts Institute of Technology has developed a computer program that reveals colors and motions in video that are otherwise invisible to the naked eye.

Holograms In The Palm Of Your Hand

A grid of 4,096 miniature antennas steer beams of infrared light to create patterns and images.  JIE SUN, MIT

Scientists at the Massachusetts Institute of Technology built a tiny device that contains a grid of 4,096 miniature antennas (64 by 64) that steer beams of infrared light to create patterns. Their so-called phased array was able to generate an image -- in this case a tiny MIT logo -- and "float" it a few millimeters out in front of the grid.

It's the first time anyone has built an array with so many components, as previous attempts only managed 16. It's also the first device of its kind that can steer each beam from an individual antennae in both the vertical and horizontal direction, making it possible to create three-dimensional pictures.

“At a basic level we’re showing that not only can you steer beams actively but also generate new and arbitrary patterns,” said Michael Watts, a professor in the Research Laboratory of Electronics at MIT. That opens up a number of possibilities in holography as well as imaging devices such as biomedical sensors, akin to radar. Communications is also a possibility, since fine control of light waves can reduce interference and noise.

Watts and his colleagues made antennas that control both the phase and intensity of the light it transmits. Two light beams that are 180 degrees out of phase will, if transmitted together, cancel each other out. Meanwhile light waves that are slightly out of phase will interfere with and reinforce each other in certain patterns, making the light look brighter or dimmer depending on how far in or out of phase they are.

That makes an image in the “far field” -- a technical way of saying that it’s some distance away. If one were to build a display like this in a living room, it would mean that the image would be out in front of it.

Phased arrays aren’t new: modern radar uses them all the time. But Watts and Sun transmitted signals at short wavelengths, in the near infrared as opposed to the radio waves of radar. They also made images, which hadn't been done before with a phased array at those wavelengths.

And because it’s possible to control the phase and intensity of the light, you get more than the illusion of depth from the front: a person standing on any side of the image could be shown a different perspective. A hologram would be truly 3-D, and if built with billions of antennas, would produce an image as detailed as any ordinary display. That's because each antennae essentially represents one pixel.

Sun and Watts didn't just set records for the size and number of antennas: they did it using ordinary microchip manufacturing methods. That means building a larger-scale device won't require retooling or building whole factories.

The MIT device used near infrared light. To make it work for visible light the only change would be the material the antennas and waveguides are made of -– it has to be something other than silicon. “We’re working on making it in the visible,” Watts said.

Via: "Discovery"

Discovered: A New State Of Matter, A New Kind Of Magnetism

Researchers at MIT have discovered a new state of matter with a new kind of magnetism. This new state, called a quantum spin liquid (QSL), could lead to significant advances in data storage. QSLs also exhibit a quantum phenomenon called long-range entanglement, which could lead to new types of communications systems, and more.

Generally, when we talk about magnetism’s role in the realm of technology, there are just two types: Ferromagnetism and antiferromagnetism. Ferromagnetism has been known about for centuries, and is the underlying force behind your compass’s spinning needle or the permanent bar magnets you played with at school. In ferromagnets, the spin (i.e. charge) of every electron is aligned in the same direction, causing two distinct poles. In antiferromagnets, neighboring electrons point in the opposite direction, causing the object to have zero net magnetism (pictured below). In combination with ferromagnets, antiferromagnets are used to create spin valves: the magnetic sensors used in hard drive heads.

In the case of quantum spin liquids, the material is a solid crystal — but the internal magnetic state is constantly in flux. The magnetic orientations of the electrons (their magnetic moment) fluctuate as they interact with other nearby electrons. “But there is a strong interaction between them, and due to quantum effects, they don’t lock in place,” says Young Lee, senior author of the research. It is these strong interactions that apparently allow for long-range quantum entanglement.

The existence of QSLs has been theorized since 1987, but until now no one has succeeded in actually finding one. In MIT’s case, the researchers spent 10 months growing a tiny sliver of herbertsmithite (pictured above) — a material that was suspected to be a QSL, but which had never been properly investigated. (Bonus points if you can guess who herbertsmithite is named after.) Using neutron scattering — firing a beam of neutrons at a material to analyze its structure — the researchers found that the herbertsmithite was indeed a QSL.

Moving forward, Lee says that the discovery of QSLs could lead to advances in data storage (new forms of magnetic storage) and communications (long-range entanglement). Lee also seems to think that QSLs could lead us towards higher-temperature superconductors — i.e. materials that superconduct under relatively normal conditions, rather than -200C.

Via: "Extreme Tech"

MIT Develops Miniature Shape-Shifting Robots

 ... these simplistic devices are a far cry from the dream of real-life Transformers. Now a group at MIT's Center for Bits and Atoms has created a robot that could point the way toward the real thing.

Developed by lab director Neil Gershenfeld, visiting scientist Ara Knaian, and graduate student Kenneth Cheung, the Milli-Motein is a reconfigurable robot that can be programmed to fold itself into a number of different shapes. And, after the robot has shifted into a new shape, it can hold that shape even when its power is cut off by using a what is known as an electro-permanent motor. Gershenfeld said, "[The Milli-Motein is] effectively a one-dimensional robot that can be made in a continuous strip, without conventionally moving parts, and then folded into arbitrary shapes."

However, the project's research paper, recently presented at the 2012 Intelligent Robots and Systems conference, warns that real world deployment of such robots will require cheaper, more durable materials, as well as better software and algorithms.

You can see the Milli-Motein in action in the video below.

Via Center for Bits and Atoms

Via: "Dvice"