Imaging optical unit

Abstract

An imaging optical unit comprises a plurality of mirrors for imaging an object field into an image field. The imaging optical unit has an image-side numerical aperture greater than 0.55. Each mirror is configured so that it can be measured by a testing optical unit having at least one DOE with a predetermined maximum diameter for test wavefront generation. For the complete measurement of all reflection surfaces of the mirrors, a maximum number of DOEs of the testing optical unit and/or a maximum number of DOE test positions of the at least one DOE of the testing optical unit comes into play, which is no more than five times the number of mirrors in the imaging optical unit. The result is an imaging optical unit in which a testing-optical measurement remains manageable even in the case of a design with an image-side numerical aperture which is relatively large.

Dependencies are inferred from the claim text.