Augustin Fresnel's echelon lens (1819)

Copyright: Bibliothèque de l'Observatoire de Paris / Sylvain Pelly

The first echelon lens designed by Augustin Fresnel and manufactured by optical engineer, François Soleil, was presented to the French Lighthouse Board, which adopted it, noting, “the superiority of brightness over parabolic reflectors.” This lens increased the lighting power of lighthouses quite significantly, at a time when maritime traffic was very busy. This type of lens is still used in many lighthouses around the world.