Fresnel lens is a succession of concentric rings, each consisting of an element of a simple lens, assembled in a proper relationship on a flat surface to provide a short focal length. The fresnel lens is used particularly in lighthouses and searchlights to concentrate the light into a relatively narrow beam.

Fresnel lenses can also be used as magnifiers or projection lenses. These lenses are also great for enlarging fine print in books, magazines, maps, telephone directories, recipes, etc. This can really be a great and creative gift to children as a toy and for those who need a visual aid. Fresnel lenses are most often used in light gathering applications, such as condenser systems or emitter/detector setups.