The extremely low thermal capacitance and high heat-transfer ability of these electrically conducting nanotube sheets, which are drawn from forest-like arrays of carbon nanotubes, enables high frequency modulation of sheet temperature over a wide temperature range, thereby providing a sharp, rapidly changing gradient of refractive index in surrounding liquid or gas.

Using these nanotube sheets, concealment can be realized over the entire optical range and rapidly turned on and off at will, using either electrical heating or a pulse of electromagnetic radiation. However, concealment is easiest to realize underwater, where the high temperature dependence of liquid refractive index can be used.

Photodeflector

Ali Aliev and his colleagues Yuri Gartstein and Ray Baughman also use this mirage effect to make photodeflectors for optical applications, like optical scanning. Advantages over prior art technologies for light deflection are low-voltage operation, the absence of an undeflected beam component and mechanical movement, large beam diameter capabilities, and low cost.

The research provides useful insights into the optimization of nanotube sheets as thermoacoustic projectors for loud speaker and sonar applications, where sound is produced by heating using an alternating electrical current.

More information can be found in the journal Nanotechnology.