  The question is considered about possibility of overcoming diffraction limit
at device, named superlens. This device is a flat slab, executed from material
with index of refraction n,equal n=-1. It is shown, what this device really can
focus the radiation to the spot, smaller than wavelength, but herewith
superlens works not as optical instrument, based on the laws of geometric
optics, but as certain matching device, for which does not exist diffraction
limit. This is possible if thickness of superlens is comparable with
wavelength, and distances from superlense to the wave source and to its image
are also in order of wavelength.
