What is Fresnel lens?
[[Image:Lentille de fresnel.jpg|thumb|upright|Lighthouse Fresnel lens, on display at the [[Musée national de la Marine]]]] [[File:Fresnel lighthouse lens diagram.png|thumb|right|250px|How a spherical Fresnel lens [[Collimated light|collimates light]]]] A '''Fresnel lens''' is an [[Lens (optics)|optical lens]], which was originally developed for [[Lighthouse]]s. It is named after its inventor, [[France|French]] [[physics|physicist]] [[Augustin-Jean Fresnel]]. The name is pronounced /freɪˈnɛl/ (fray-NELL), the 's' is silent. Before Fresnel, [[Georges-Louis Leclerc, Comte de Buffon|Buffon]] and [[marquis de Condorcet|Condorcet]] proposed a similar design, as a way to make large [[burning lens]]es. The design allows the construction of lenses of large [[aperture]] and short [[focal length]] without the weight and volume of material that would be required in conventional [[lens (optics)|lens]] design. Compared to earlier lenses, the Fresnel lens is much thinner. More light can pass through. Lighthouses that use these kind of lenses can be seen from farther away. [[File:Flat flexible plastic sheet lens.JPG|thumb|left|250px|Close-up view of a flat Fresnel lens shows concentric circles on the surface]] {{-}} {{physics-stub}} [[Category:Optics]]