Analytical equations for a nonconfocal stigmatic three-freeform-mirror system

This paper presents a novel method, to the best of our knowledge, to design three-freeform-mirror systems from scratch. The technique consists of getting an initial setup, before optimization, which is directly obtained from the set of all possible stigmatic three-freeform-mirror systems. Then, deformation coefficients are added to each surface and optimized to reduce aberration produced by additional fields. The method has been tested and the results are as expected.