The Secret To A Real Invisibility Cloak
3D invisibility cloak unveiled. The first device to hide an object in three dimensions has been unveiled by a group of physicists in the UK and Germany. While the design only cloaks micro-scale objects from near-infrared wavelengths, the researchers claim that there is nothing in principle to prevent their design from being scaled up to hide much larger artefacts from visible light. The origins of this design date back to 2006, when David Smith and colleagues at Duke University in North Carolina created a cloak that could bend microwaves around an object, like water flowing around a smooth stone. This early cloak was made using a metamaterial – an artificially constructed material with unusual electromagnetic or other properties – which consisted of a cylinder built up from concentric rings of copper split-ring resonators. This first cloak, however, only worked in two dimensions – in other words, looking at the cylinder from above revealed the presence of the shielded object. Carpet cloak. Now Tolga Ergin and colleagues at Karlsruhe Institute of Technology in Germany, together with John Pendry of Imperial College in London, have overcome this problem by creating a “carpet cloak”. Proposed in 2008 by Pendry and Jensen Li, this involves hiding an object underneath a bump on the surface of an otherwise
smooth material – just as something might be hidden under a carpet – and then smoothing out the resulting bump. This is achieved by creating a bump on a flat mirror and then placing onto the mirror a layer of metamaterial with optical properties such that light appears to reflect off the mirror as if the bump were not there. This technique was demonstrated experimentally at two different wavelengths last year, with Smith’s group showing that it worked in the microwave region while researchers at Berkeley and Cornell University near New York obtained similar results at infrared wavelengths. However, these cloaks were also limited to just two dimensions. Ergin’s group has made a carpet cloak in three dimensions by stacking nanofabricated silicon wafers on top of one another in a “woodpile” matrix and then filling in the gaps between the wafers with varying amounts of polymer. This achieves the desired distribution of refractive indices within the structure. Hiding the bump. The cloak structure was then placed on top of a reflective gold surface containing a bump, leading to a cloaking effect using unpolarized light with wavelengths between 1.4 and 2.7 µm – the near-infrared. Importantly, this effect held for viewing angles up to 60 degrees (with zero degrees representing viewing in just two dimensions). The bump, however, was very small – just 30 µm (10–6 m) × 10 µm × 1 µm. Team member Martin Wegener says it should be possible to use existing technology to make the cloak bigger in order to hide larger objects, but that this approach would be extremely time-consuming. “Faster nanofabrication tools will have to be developed allowing for three-
dimensional structures,” he adds. For Wegener the aim of the work is not about focusing all efforts on creating invisibility cloaks, but is about exploring a range of applications in transformation optics. This involves calculating what kind of material is needed to bend light in a certain way, by considering light trajectories as the result of the warping of space. Wegener says that transformation optics should lead, for example, to the design of better antennas or smaller optical resonators. Smith describes the latest work as “very exciting” and agrees that its real importance lies in the development of transformation optics. “Demonstrations like these are paving the way for transformation optical design to become an established design methodology, like ray-tracing,” he says.news from physicsworld.com ~ The Karlsruhe Institute of Technology (KIT) is an academic research and education institution resulting from a merger of the university (Universität Karlsruhe (TH)) and the research center (Forschungszentrum Karlsruhe).It is located in the city of Karlsruhe, Germany. The university was also known as Fridericiana and was founded in 1825. In 2009, it merged with the former national nuclear research center founded in 1956 as the Kernforschungszentrum Karlsruhe (KfK). One of nine German Excellence Universities, the KIT is one of the leading technical universities in Germany, ranking 6th in Europe in terms of scientific impact. The University of Karlsruhe was founded as Polytechnische Schule, a polytechnical school, on October 7, 1825. It was modeled upon the École polytechnique in Paris. In
1865, Grand Duke Frederick I of Baden (German: Friedrich) raised the school to the status of a Hochschule, a high educational institute. Since 1902 the university also has been known as the Fridericiana in his honour. In 1885 the institution was renamed a Technische Hochschule, Institute of Technology, and in 1967 it became Universität, a full university, entailing the right to award regular doctorate degrees. Nevertheless in 1899 all technical universities, therefore including the University of Karlsruhe, were granted the right to award doctorate degrees for engineering identified as Dr. Ing.. The University of Karlsruhe has been one of the leading German institutions in computer science. A central computer laboratory was founded in 1966. The department of informatics was established three years later along with the possibility to study informatics in a regular course. On 2 August 1984 the university received the first email in Germany. On April 6, 2006 a contract for the foundation of the Karlsruhe Institute of Technology (KIT) was signed by Professor Horst Hippler and Dr. Dieter Ertmann from the University of Karlsruhe, and Professor Manfred Popp and Assistant Jur. Sigurd Lettow from Forschungszentrum Karlsruhe. The name was selected to emulate the Massachusetts Institute of Technology (MIT), the leading technical university in the United States. In 2008 Hans-Werner Hector, SAP Co-Founder, raised a 200 Million Euro fund to support excellent researchers within the university. Interestingly Hans-Werner Hector is the only founder of SAP which did not graduate regularly at the University of Karlsruhe but was given an honorary doctorate degree for his support of intellectually gifted children in 2003. The
first step to bring together the university and the research center was already made in 1985, when the Institut für Meteorologie und Klimaforschung (Institute for Meteorology and Climate Research) was founded. Both institutes, the university and the research center were merged. The university and the research center have always cooperated but the cooperation increased by Juli 2006 when the KIT was formally founded. The main reason for establishing the KIT was the participation of the university of Karlsruhe in the German Universities Excellence Initiative, including the chance to get a maximum grant of 50 Mio. € p.a. from the excellence initiative. In February 2008, the merger of the University of Karlsruhe and the Forschungszentrum Karlsruhe forming the Karlsruhe Institute of Technology was agreed upon by the state Baden-Württemberg and the federal German government.The corresponding state law was passed on 8 July 2009. KIT was formally established on 1 October 2009.The university allowes a broad band of education with the possibility of cross studies and work. The studium generale(Engl.: General studies) was established in 1949 allowing students to attend lectures not directly pertaining their study field. The “Zentrum für Angewandte Kulturwissenschaft und Studium Generale” (Engl.: Center for applied culture and general studies) was founded in 1989 to support the students as a central institution for their interdisciplinary study. Nowadays it offers specialised qualifications in the fields of “Leadership and
Entrepreneurship”, “Media – Culture – Communication”, “Internationalisation and intercultural decision-making and responsibility”, “Diversity Management”, “European Integration and Identity Studies ” as well as the classical studium generale. A possibility for a concomitant study in applied culture science is given as well. In 1979 the “Interfakultatives Institut für Anwendungen der Informatik” (Engl.: Interfacultative institute for applications of informatics) was founded. It binds together research in the fields of physics, mathematics and engineering which are based on computer science. Its mathematical pendant is the “Institut für Wissenschaftliches Rechnen und Mathem. Modellbildung” (Engl.: Institute for scientific calculations and mathematical modeling). Its aim is to enhance the exchange between mathematics and engineering in the fields of scientific calculations. The “Interfakultatives Institut für Entrepreneurship” (Engl.: Interfacultative institute for entrepreneurship) was established by SAP funding. Its teaching professors are entrepreneurs on their own. Current professor is Götz Werner, founder of dm – Drogeriemarkt. In 2001 the Center for Functional Nanostructures (CFN) was established. It merges the fields of material sciences, biology, chemistry, engineering and physics which are related to nano technology. The CFN is one of the three Exzellenzzentren (Engl.:
Excellence Instituitions) of the University of Karlsruhe. A second interdisciplinary excellence institution is the Center for Disaster Management and Risk Reduction Technology (CEDIM). The Karlsruhe School of Optics & Photonics (KSOP) was established in 2006 as a public funded project by the Deutsche Forschungsgemeinschaft (DFG) within the scope of the Excellence Initiative by the German Federal and State Governments to promote Science and Research at German universities. KSOP is the first graduate school at the Universität Karlsruhe (TH) and covers the research areas Photonic Materials & Devices, Advanced Spectroscopy, Biomedical Photonics and Optical Systems. It is supported by several Institutes and Professors of the university. The Steinbuch Centre for Computing (SCC), named after Karl Steinbuch, is the institution which was formed in 2008 out of the merging process between the main computer facilities of the University of Karlsruhe and the Forschungszentrum Karlsruhe. It is responsible for the university’s IP connectivity and provides central services (Mail, Web, Campus management) for students and employees. It supplies students with 10 full equipped computer rooms, one professional print office and a wireless network over the whole campus area. Some departments, like computer science, physics, and mathematics, run their own computer rooms as well. The SCC runs some of the fastest computers in Germany. * HP XC4000 (750 nodes with 4 cores each, 15.77 TFLOPS), * a cluster bought by a corporation of institutes of different disciplines (200 nodes with 8 cores each, 17.57 TFLOPS), * parallel calculator HP XC6000 (1.9 TFLOPS) * the two vector parallel calculators NEC SX-8R and NEC SX-9 On August 2, 1984 Michael Rotert, a research fellow at University of Karlsruhe, received the first email ever sent to Germany at his address. ~ Kalogeros Steel, Director GoodNews International Edition
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