  The emission of pions produced within a dense, strongly-interacting system of
matter in the presence of strong radial flow and absorption is described using
a relativistic optical model formalism, replacing the attenuated or
unattenuated plane waves of earlier emission function approaches with
``distorted wave'' solutions to a relativistic wave equation including a
complex optical potential. The resulting distorted-wave emission function model
(DWEF) is used in numerical calculations to fit HBT correlations and the
resonance-corrected pion spectrum from central-collision STAR Au+Au pion data
at $\sqrt{s}= 200$ GeV. The parameters of the emission function are constrained
by adopting a pion formation temperature taken from lattice gauge calculations
and a chemical potential equal to the pion mass suggested by chiral symmetry
restoration. Excellent agreement with the STAR data are obtained. The
applications are extended by applying linear participant scaling to the
space-time parameters of the model while keeping all other parameters fixed.
This allows us to predict HBT radii over a range of centralities for both Au+Au
and Cu+Cu collisions. Good agreement is found with STAR HBT data for all but
the most peripheral collisions.
