Cascaded diffraction in optical systems. Part I: simulation model

In every real optical system, the light beam or ray bundle is laterally limited by diaphragms or lens boundaries. Therefore, from a rigorous point of view, a diffraction calculation of the point spread function by assuming a truncation at the exit pupil is a simplification. If several boundaries at different z positions inside a system truncate the rays, cascaded diffraction occurs and the field in the exit pupil is modified in amplitude and phase by the edge diffraction effects at all relevant boundaries. A simple model for a fast estimation of these effects and a rule of thumb for real optical systems are worked out in this work.