Figure 1: Working principle of the spherical hyperlens.
From: Spherical hyperlens for two-dimensional sub-diffractional imaging at visible frequencies
(a) Schematic of a spherical hyperlens comprised of nine pairs of silver and titanium oxide layers. (b) Cross section of the spherical hyperlens along the green incident plane. The object with sub-wavelength features is carved in a chromium layer atop the silver–titanium oxide multilayer (also shown in light blue in a). The transverse magnetic (TM) component of unpolarized light relative to the plane is labelled by K. (c) The isofrequency contour for the TM modes in the hyperlens compared with isotropic medium made of silicon oxide. The arrows, which are of unit length and on the ultraflat curve, show that all the k components (including those much larger than the wave vectors available in dielectrics) propagate along the same radial direction, indicating the lack of diffraction.
