Removing image artefacts in wire array metamaterials

Hyperlenses and hyperbolic media endoscopes can overcome the diffraction limit by supporting propagating high spatial frequency extraordinary waves. While hyperlenses can resolve subwavelength details far below the diffraction limit, images obtained from them are not perfect: resonant high spatial frequency slab modes as well as diffracting ordinary waves cause image distortion and artefacts. In order to use hyperlenses as broad-band subwavelength imaging devices, it is thus necessary to avoid or correct such unwanted artefacts. Here we introduce three methods, namely convolution, field averaging, and power averaging, to remove imaging artefacts over wide frequency bands, and numerically demonstrate their effectiveness based on simulations of a wire medium endoscope. We also define a projection in spatial Fourier space to effectively filter out all ordinary waves, leading to considerable reduction in image distortion. These methods are outlined and demonstrated for simple and complex apertures.