Fermat's principle
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Fermat's principle, also known as the principle of least time, is the link between ray optics and wave optics. Fermat's principle states that the path taken by a ray between two given points is the pa
Fig. 3: An experiment demonstrating refraction (and partial reflection) of rays – approximated by, or contained in, narrow beams
Posthumous engraving of Alhazen, used as the frontispiece to Johannes Hevelius, Selenographia, 1647
Pierre de Fermat (1607 –1665)
Christiaan Huygens (1629–1695)
Hero of Alexandria
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Hero of Alexandria was a Greek mathematician and engineer who was active in Alexandria during the Roman era. He has been described as the greatest experimentalist of antiquity and a representative of
Fermat's principle
…the OPL; it is the foundation of Lagrangian and Hamiltonian optics. If a ray follows a straight line, it obviously takes the path of least length. Hero of Alexandria, in his Catoptrics (1st century CE), showed that the ordinary law of reflection off a plane surface follows from the premise that the total length of…
Depiction in the Codex of Saint Gregory Nazianzus, Greek manuscript, 9th cent.
The book About automata by Hero of Alexandria (1589 edition)