
Formula to design freeform singlet free of spherical aberration and astigmatism - mzs
https://www.osapublishing.org/ao/abstract.cfm?uri=ao-58-4-1010
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mzs
background on Wasserman-Wolf problem:
[https://phys.org/news/2019-08-physicists-year-old-optical-
pr...](https://phys.org/news/2019-08-physicists-year-old-optical-problem.html)

