Lenses are used to focus light. But on larger scales, conventional lenses can become too massive. The Fresnel lens allows for a lens of large aperture and short focal length useful for efficient magnification and concentration on any scale. Physicist Augustin Jean Fresnel designed its clever surface which is divided into concentric ridges. By layering these ridges to be on the same curvature, it becomes a lightweight alternative for most projects. 

These lenses are not unlike a reverse telescope. Instead of bringing in light from far away, these lenses are capable of concentrating light to a narrow point to reach great distances. 

Used in lighthouses to bring ships to safety through their concentrated beam of light, they have been called "the invention that saved a million ships".