Traditional methods of assessing optical quality are based primarily on global parameters such as the rms wavefront error or performance quantifiers such as the optical quality factor (OQF). Global parameters that characterize performance, such as rms, are indirectly
correlated with imaging quality because they do not account for the spatial distribution of the errors in the aperture. Although the conventional OQF is related to performance for systems affected with arbitrary aberration forms, it does not supply information that is useful for correcting the local regions of an optical component (e.g., mirror surface). A system is presented that is directly correlated with imaging quality. The system, denoted localized wavefront performance analysis (LWPA), evaluates quality on the basis of a subpupil or local OQF (LOQF) that is specific to discrete regions of the aperture. This information is used to produce a performance map, LOQF versus pupil position, to pinpoint for correction those wavefront error regions with the lowest values. LWPA theory is described heuristically and a supporting test case is presented.