AAWSAP DIRD, Metamaterials for Aerospace Applications, April 2010

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Note that the hyper-lens concept does not require employing a bulky near-field
scanning optical microscope. However, the practical implementation of the hyper-lens is
by no means simple. The original implementation required depositing the sample on the
curved surface of the hyper-lens. A more practical implementation of the super-lens has
been theoretically proposed by another group (Reference 26). The concept is shown in
Figure 8. The hyper-lens involves an array of thin metallic wires converging towards the
tip. As is demonstrated, a dense array of metal wires separated by much less than the
wavelength constitutes a metamaterial with the indefinite permittivity tensor.
Specifically, the tensor component along the wires is given by:
(3)
where the z component is along the wires and perpendicular direction is normal to the
wires. Because the only propagating waves are the TEM waves satisfying the
o/ =k; c2 dispersion relation, this meta-medium is strongly anisotropic and supports
sub-wavelength waves which perform imaging. The spatial resolution is given by the
spacing between wires. Figure 8 (right panel) shows the magnified image of a small
('A/25) object placed at the tip of the hyper-lens. The magnification factor is Sx.
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Figures. Hyper-Lens Based on a Converging Array of Metal Wires. A small object can be placed at the tip,
illuminated from the top, and magnified by the expanding array of wires. Left panel : schematic. Right panel: A./25
object magnified by a factor Sx by the expanding hyper-lens. This hyper-lens can operate at mid-IR frequencies.
(Reference 26)
Another concept for sub-wavelength imaging employing metamaterials is the so-called
Far-Field Super-Lens (FSL). The concept is pioneered in Reference 27. The idea is
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