The 2021 IODC lens design problem: the down under lens

The lens design problem for the 2021 IODC is to design a 100 mm focal length lens where if the lens is flipped end-to-end but the radii are not reversed in sign, the lens has to perform the same as in its original form. The lens is used monochromatically. The goal of the problem is to maximize the product of the entrance pupil diameter and the semi-field of view while holding the RMS wavefront error to ≤ 0.070 wave within the field of view. There were 43 entries from 13 different countries. Three different commercial lens design programs were used, along with four in-house programs. The winning entry from Damien Gawron has an entrance pupil diameter of 198.4083 mm and a semi-field of view of 90° for a merit function product of 17,857 out of a maximum possible 18,000.