Sunday, March 1, 2015

Quick History of Cloaking Devices

Dr. Ramki Kalyanaraman, associate professor of materials science engineering, and his colleague Dr. Gerd Duscher at UT are not the only people working to develop cloaking technologies.
From its 1966 debut in a Star Trek episode to its present form, the science of invisibility has captured the imaginations of everyone from screenwriters to physicists.
Invisibility as a concept has been used in fiction since the days of Plato.
Most commonly associated with magic, people become invisible by putting on a cloak or a cap or by gaining magical powers through a pact with the devil as seen in Christopher Marlow’s Doctor Faustus. It first appeared on the big screen in the 1933 science fiction film, The Invisible Man and continues to be a theme in comic books, video games and literature to this day.
However, it wasn’t until 1968 that the term “cloaking device” was introduced to the general public. If you are a Trekkie, you probably remember when a Romulan Bird of Prey armed with a cloaking device attacked the Starship Enterprise in the 1966 episode titled “Balance of Terror.”
It was in the 1968 episode “The Enterprise Incident” that Star Trek screenwriter Paul Schneider gives invisibility technology a name: Cloaking device.
In 1997, J.K. Rowling published Harry Potter and the Philosopher’s Stone, in which Harry Potter receives a cloak of invisibility as a gift. However, up until this point, invisibility and cloaking were still a concept of science fiction.
The British military experimented with what is known as “active cloaking” technologies in 2009. This technology uses video cameras to record the landscape and then projects the image on the front of an object, such as the hull of a tank.
Delays in the video feed and its one-dimensional view turned out to be the main problems with this cloaking technology.
The real break-through with cloaking devices came in 2006 when physicists from Duke University announced they had built the world’s first invisibility cloak using what was novel in 2006: Metamaterials.
The physicists developed a matrix of metal wires and loops on the nanoscale to control electromagnetic radiation. However, the technology only worked in two dimensions and on microwaves.
Picking up on the theme of metamaterials as the potential answer to true invisibility, scientists at the University of California, Berkeley, developed metamaterials in 2008 with extraordinary capabilities to bend electromagnetic waves. For the first time, scientists used 3-D materials to reverse the natural direction of visible and near-infrared light.
A year later, they develop a nanostructured silicon, or carpet cloak, that hid objects underneath it from optical detection. The main limitation in this case is the cloak is still visible.
In 2010, scientists at Tufts and Boston universities developed an invisibility cloak fit for a queen and capable of manipulating terahertz waves.
The cloak is made from a one centimeter square piece of silkworm silk and is stenciled with 10,000 gold resonators. Scientists blasted the metamaterial with terahertz waves and detected a resonance when usually, they would blast right through.
Since that time, advances in the use of metamaterials have increased significantly and scientists take one step closer to making a cloak of invisibility a possibility for aspiring Romulans and Harry Patter fans everywhere.

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