Invisibility has become another step closer

July 21, 2008, 2:47 am

invisibility has become another step closer 
invisibility has become another step closer   Scientists at the University of California for the first time created a material that can change the direction of the proliferation of visible and near infrared light. This development may lay the foundation for improving the permission of optical images nanoshem high-performance computers and creating devices that provide invisibility.
One technology uses metal layers nanosetki. Another - silver nanoniti. Applications developed metamaterialov can change the normal spread of light, forcing bypass electromagnetic waves around the object. Using this technology will allow optical microscopes to distinguish individual molecules of DNA viruses or, with permission microscope should be less than the wavelength of light.
The reason for such behaviour is in a negative index of refraction. All material of natural origin have a positive refraction. For example, if a positive index of refraction we see, looking at the pond as a fish swims in water, then at a negative an impression that the same fish above the water surface.
have already been reported that some scientists managed to create metamaterialy working at optical frequencies, but these materials are limited two-dimensional structure of the single artificial atoms whose properties of refraction can not be determined, a three-dimensional materials with a negative refraction can work only with long microwaves. And previous metamaterialy were based on the physics of resonance, to achieve negative refraction it was necessary to compel them vibrate at a certain frequency.
The man sees the world through a range of electromagnetic radiation, called visible light, with a wavelength of 400 nanometers to 700 nanometers. To achieve negative refraction must have a size smaller than the length of the electromagnetic wave. It is therefore not surprising that the microwave is already reached, the length of whom were 1-300 mm.
Metal layers nanosetki
Researchers stacked together successive layers of silver and magnesium fluoride non-conducting. As a result, on short wave (1500 nm, near infrared band) scientists managed to achieve negative refraction. Another group used to grow oxide matrix nanonitey silver in the porous aluminum oxide. The distance between the threads set smaller wavelength of light in the visible spectrum.
Silver nanoniti
nanonitey vertical configuration, which built parallel, is intended only for interaction with the electric field of light waves. Magnetic field, which varies perpendicular to the plane, virtually no effect on nanoniti, significantly reducing energy losses.
Thus, both the material reaches a negative index of refraction by minimizing the energy lost during passage of light through the sample. In the case of nanosetkoy, tightly linked nanotsepi miss the light and reduce losses in passing through the metal layers. Researchers for the first time been able to observe negative refraction wave length of 660 nm, corresponding visible light red.
Innovation is that negative refraction achieved without techniques. This advantage will significantly improve the effectiveness of antennas by reducing interference. The negative refraction factor can also reverse the Doppler effect. However, despite it will be possible to use a negative index of refraction in a wide range of waves, before the emergence of invisibility cloaks are far because these metamaterialy made of metal and very fragile, and organization of large-scale production is also an issue. While this is still a big step forward.


• нанонити
• silver invisibility
• nanoniti
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