Here the role and influence of aberrations in optical imaging systems
employing partially coherent complex scalar fields is studied. Imaging systems
require aberrations to yield contrast in the output image. For linear
shift-invariant optical systems, we develop an expression for the output
cross-spectral density under the space-frequency formulation of statistically
stationary partially coherentfields. We also develop expressions for the output
cross{spectral density and associated spectral density for weak-phase,
weak-phase-amplitude, and single-material objects in one transverse spatial
dimension
