We propose an approach to far-field optical imaging beyond the diffraction limit. The proposed system allows
image magnification, is robust with respect to material losses and can be fabricated by adapting existing
metamaterial technologies in a cylindrical geometry.
We develop the ray optic Hamiltonian for a cylindrically anisotropic medium such as the hyperlens using the
semiclassical approximation, which reveals an interesting spiralling behaviour of ray trajectories and also gives
an alternative explanation to the subdiffraction far field imaging behaviour of the device. The Hamiltonian can
be further used to derive the material parameters needed for non magnetic cloaking. Numerical simulations of
gaussian beam scattering from these devices confirm the respective semiclassical results.
We propose an approach to far field optical imaging below the diffraction limit, based on dielectric metamaterials with strong anisotropy. As opposed to the "superlens" that relies on negative index materials, our method allows image magnification and is robust with respect to material losses.
We develop a new approach to materials with negative refraction index which can be implemented for optical and infrared frequencies. In contrast to conventional designs which require simultaneously negative dielectric permittivity and magnetic permeability, our system is intrinsically non-magnetic and makes use of an anisotropic dielectric constant to provide negative refractive index in waveguide geometry. The proposed approach is not limited to the proximity of a resonance and thus allows for low loss, critical for super-lensing applications.
We demonstrate that a nanostructured plasmonic composite material
can show negative index of refraction at infrared and optical frequencies. In contrast to conventional negative refraction materials, our design does not require periodicity and thus is highly tolerant to fabrication defects. Moreover, since the proposed material is intrinsically non-magnetic (μ ≡ 1), its performance is not limited to proximity of a resonance so that the resulting structure has relatively low loss. We develop the analytical description of the relevant electromagnetic phenomena and justify our analytic results via numerical solutions of Maxwell equations.
The peculiarities of radar images and the problems of their filtering are considered. A two-stage procedure of radar image despeckling based on successive application of the local statistic Lee and sigma filters is proposed. The recommendations concerning filter parameter selection are presented. The performance characteristics of the proposed procedure are evaluated for a set of test artificial images. It is shown that the two-stage despeckling can be successfully applied to both images formed by side look aperture radar (SLAR) or synthetic aperture radar (SAR). An available trade-off of filter basic properties is provided. The examples for real data demonstrating the proposed procedure efficiency and benefits are also given.
The characteristics of snow backscattering in microwave band are considered. It is shown that they depend upon many parameters describing the state of snow cover. The basic dependences obtained from theory of radar backscattering and experimental data are discussed and compared. Real radar remote sensing data for different dates in fall/winter period are presented for Eastern regions of Ukraine. It is demonstrated that the effects predicted theoretically are observed for remote sensing images obtained from side-look radar installed on the satellite “Ocean”. It is also shown that remote sensing means in some conditions permit to get the maps of snow cover thickness but in this case the reference data from several on-land meteorological stations are needed for calibration purposes.
The outcomes of experimental investigations of shadow conical refraction, when the optical harmonics are generated, are represented in the paper for a biaxial crystal of lithium formiate. A technique allowing visual observation of conical refraction 'rings' is described. The contribution of different types of light wave interactions to a transformed radiation is mentioned.