Impedance-matched hyperlens

We propose an approach to optical imaging beyond the diffraction limit, based on transformation optics in concentric circular cylinder domains. The resulting systems allow image magnification and minimize reflection losses due to the impedance matching at the input or output boundaries. While perfect impedance matching at both surfaces can be obtained only in a system with radius-dependent magnetic permeability, we demonstrate that comparable performance can be achieved in an optimized nonmagnetic design. (C) 2007 Optical Society of America.