Diffraction theory and focusing of light by a slab of left-handed material

A diffraction theory in a system consisting of left- and right-handed materials is proposed. The theory is based upon the Huygens's principle and the Kirchhoff's integral and it is valid if the wavelength is smaller than any relevant length of the system. The theory is applied to the calculation of the smearing of the foci of the Veselago lens due to the finite wavelength. We show that the Veselago lens is a unique optical instrument for the 3D imaging, but it is not a superlens as it has been claimed recently. (C) 2003 Elsevier B.V. All rights reserved.