Benny Ran
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A group of scientists from the USA and the UK demonstrated an artificial material that can produce a magnetic response to radiation at terahertz frequencies. The development of this material is another step towards the development of the innovative T-ray devices. The innovation, which was reported in Science magazine from March 5, may have many uses in the fields of imaging for biology and security purposes, biomolecular fingerprints, remote sensing and navigation in conditions of zero visibility.
Theorist John Pendry of King's College London, who is one of the authors of the document, described the preparation of the material as technological virtuosity, and said that he expects amazing applications. "This is the first material that responds magnetically to terahertz frequencies. We have proven that we can do this, and this has a powerful message for the research community."
The terahertz frequencies are in a vast area that has not yet been explored in the electromagnetic spectrum, between infrared radiation and microwave radiation, known as far infrared radiation. The terahertz frequency is 1 trillion cycles per second and its wavelength is 0.1 mm to XNUMX mm. Since it is not ionizing and has no harmful effects on DNA, radiation is considered safe.
The researchers from the University of California at Los Angeles, the University of California at San Diego and King's College London are jointly developing artificial materials that respond magnetically to terahertz frequencies, infrared and light rays, since there are almost no natural materials that respond to these frequencies.
The pursuit of the artificial materials, or metamaterials, stems from the desire to explore a strange property known as the "key that breaks negative light rays" that exists only in these materials. The diagnosis of normal optical devices is limited by the wavelength of the radiation applied (for example light or X-rays), but in a series of studies based on the work of the Russian physicist Victor Vassalgo from 1968, Prof. Pandry predicted in 2000 the existence of devices that are able to focus features whose length is shorter than the length of the light rays.
These innovative lenses, called "perfect lenses", break the wavelength barrier. The diagnosis is limited only by the quality of the materials from which the lenses are made. The perfect lenses are based on a phenomenon that was hypothesized by Weselgo, who researched new electromagnetic materials whose natural response to electric and magnetic fields is reversed. He called them "ethereal" materials because their reaction is opposite to the direction of the energy flow attributed to the light rays.
Among the many strange properties of the etheric substances, Vassalgo found that following the refraction of a light ray by an etheric substance, it is directed in the opposite direction to that in which it is directed following refraction by water or glass. This phenomenon has been called a key that breaks negative light rays. The ethereal materials react in the opposite way both to electric and magnetic fields and to light rays. However, such materials were not found and discarded in nature, and field studies were not carried out for thirty years.
In 1999 Prof. Pendri joined a team of scientists from the Marconi company to develop a new group of metamaterials. The structure of the materials was designed to scale between the dimensions of the atom and the wavelength of the radiation. The properties of materials are not limited by the periodic table and scientists can design the electromagnetic reactions as they wish, as long as they conform to the laws of electromagnetics. The team proposed the first design of a magnetic metamaterial, in which, depending on the resonance, the magnetic response is determined: positive or negative. The design is called a "truncated ring" and is similar to the letter C.
Initially, the truncated ring operated at microwave frequencies. To get a response at terahertz frequencies, the scientists increased the resonance and reduced the spacing between the material components, since its structure must be smaller than the wavelength of the radiation. "We haven't even dreamed of some of the uses of the technology yet," said Prof. Pendri. "Remember the first laser beams. Did anyone then dream of the uses they are made of today"?
Yadan the third millennium
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