  We present a method for amplifying a single or scattered impurities immersed
in a background gas of ultra cold atoms so that they can be optically imaged
and spatially resolved. Our approach relies on a Raman transfer between two
stable atomic hyperfine states that is conditioned on the presence of an
impurity atom. The amplification is based on the strong interaction among atoms
excited to Rydberg states. We perform a detailed analytical study of the
performance of the proposed scheme with particular emphasis on the influence of
many-body effects.
