  We show that two-dimensional arrays of thin metallic wires can guide
transverse electromagnetic (TEM) waves and focus them to the spatial dimensions
much smaller that the vacuum wavelength. This guiding property is retained for
the tapered wire bundles which can be used as multi-channel TEM endoscopes:
they capture a detailed electromagnetic field profile created by deeply
sub-wavelength features of the studied sample and magnify it for observation.
The resulting imaging method is superior to the conventional scanning
microscopy because of the parallel nature of the image acquisition by multiple
metal wires. Possible applications include terahertz and mid-infrared endoscopy
with nanoscale resolution.
