Parametric analysis of the effect of scattered light upon the modulation transfer function

The modulation transfer function (MTF) is widely used as the image quality criterion of choice for imaging applications where fine detail in extended images needs to be specified or evaluated. We present a parametric analysis of the effect of scattered light upon the MTF of an imaging system and illustrate the results for three specific applications: (1) a visible Newtonian telescope with moderately good optical surfaces which produce no significant effect upon the MTF, (2) an extreme ultraviolet Newtonian telescope where scattering effects can dominate both diffrac-tion effects and aberrations in the resulting image degradation even for state-of-the-art optical surfaces, and (3) a visible system made up of three diamond-turned off-axis aspheric mirrors where we use the predicted MTF to estimate whether post-polishing is required (huge cost and schedule impact) to meet a specific image quality requirement. 1 Introduction The modulation transfer function (MTF) is widely used as the image quality criterion of choice for imaging applications where fine detail in extended images needs to be specified or evaluated. 1–3 This is particularly true for imaging systems degraded by diffraction effects and geometrical aberrations. However, there seems to be a dearth of optical engineering literature concerning the effects of scattered light upon the MTF. Exceptions include the medical x-ray imaging community involved in projection mammography 4 and the vision community where intraocular scattering effects are of concern.