Fresnel lens
A Fresnel lens is an optical lens, which was originally developed for Lighthouses. It is named after its inventor, French physicist Augustin-Jean Fresnel. The name is pronounced  /freɪˈnɛl/ (fray-NELL), the 's' is silent. Before Fresnel,  Buffon and Condorcet proposed a similar design, as a way to make large burning lenses.