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Carbon nanotubes are allotropes of carbon with a cylindrical structure. These cylindrical molecules have extraordinary properties, opening doors to new advancements in nanotechnology, electronics, optics and other fields of materials science. Carbon nanotubes exhibit amazing thermal conductivity and mechanical and electrical properties. Scientists are now manipulating carbon nanotubes to form mirages which seems to make things disappear beneath it by refraction. Video and details after the break.Sadly though, the current experimental project only works under water. The mirage effect comes from thermally modulated transparent carbon nanotube sheets. The manipulation of the sheet of nanotubes origin from photothermal deflection which induces sharp changes in both current and temperature, generating a rapid change of refractive index in the surrounding liquid or gas.
The original papers were published in IOP Science under the category of Nanotechnology on October 3 2011. Here is the abstract of the entire article.
The single-beam mirage effect, also known as photothermal deflection, is studied using a free-standing, highly aligned carbon nanotube aerogel sheet as the heat source. The extremely low thermal capacitance and high heat transfer ability of these transparent forest-drawn carbon nanotube sheets enables high frequency modulation of sheet temperature over an enormous temperature range, thereby providing a sharp, rapidly changing gradient of refractive index in the surrounding liquid or gas. The advantages of temperature modulation using carbon nanotube sheets are multiple: in inert gases the temperature can reach > 2500 K; the obtained frequency range for photothermal modulation is ~ 100 kHz in gases and over 100 Hz in high refractive index liquids; and the heat source is transparent for optical and acoustical waves. Unlike for conventional heat sources for photothermal deflection, the intensity and phase of the thermally modulated beam component linearly depends upon the beam-to-sheet separation over a wide range of distances. This aspect enables convenient measurements of accurate values for thermal diffusivity and the temperature dependence of refractive index for both liquids and gases. The remarkable performance of nanotube sheets suggests possible applications as photo-deflectors and for switchable invisibility cloaks, and provides useful insights into their use as thermoacoustic projectors and sonar. Visibility cloaking is demonstrated in a liquid.Source
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