Freeform imaging systems: Fermat's principle unlocks 'first…
Freeform imaging systems: Fermat's principle unlocks 'first time right' design
https://phys.org/news/2021-05-freeform-imaging-fermat-principle.html
Freeform imaging systems: Fermat's principle unlocks 'first time right' design
https://phys.org/news/2021-05-freeform-imaging-fermat-principle.html