Method for designing freeform surfaces off-axial imaging system with a real exit pupil

摘要

A method for designing freeform surface off-axial three-mirror imaging system with a real exit pupil is related. An initial system is established. A surface located before the real exit pupil is defined as surface M. A number of feature rays are selected. A number of ideal intersections of the feature rays with surface M are calculated. A number of intersections of the feature rays with each surface before surface M are calculated, and each surface before surface M is obtained by surface fitting. A number of intersections of the feature rays with surface M are calculated, and surface M is obtained by surface fitting. Surface M substitute for an initial surface, and repeating steps above, until the intersections of the feature rays with surface M are close to the ideal intersections, and the intersections of the feature rays with an image surface are close to the ideal image points.