  We study numerically, by means of the pseudospectral time-domain method, the
unique features of imaging by a flat lens made of a left-handed metamaterial
that possesses the property of negative refraction. We confirm the earlier
finding that a left-handed flat lens can provide near-perfect imaging of a
point source and a pair of point sources with clear evidence of the
sub-wavelength resolution. We illustrate the limitation of the resolution in
the time-integrated image due to the presence of surface waves.
