  We investigate in this paper the imaging properties of an absorptive
left-handed material (LHM) slab. For a line source, a geometric explanation to
the reason of the thickness limitation on an ideal slab is given. For a lossy
slab, the imaging properties are determined by the wavelength, the slab
thickness, the distance from the source to the nearer boundary of the slab, and
the absorption effect. Varying the ratios between these quantities, the image
width can be changed from wavelength to subwavelength scale. In the former
situation, the energy density is mainly concentrated at the two image spots. In
the later case, though image of subwavelength width appears on the focal plane,
however, most energy is located at about the two boundaries of the slab, and
beyond the boundaries the wave amplitude decays exponentially. The relations
between the subwavelength imaging and uncertainty principle is also discussed.
