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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".
Dimensions: 5.25" x 3.75"
A Fresnel lens is a type of composite compact lens originally developed by French physicist Augustin-Jean Fresnel (1788–1827) for lighthouses. It has been called "the invention that saved a million ships." The design allows the construction of lenses of large aperture and short focal length without the mass and volume of material that would be required by a lens of conventional design. A Fresnel lens can be made much thinner than a comparable conventional lens, in some cases taking the form of a flat sheet. A Fresnel lens can capture more oblique light from a light source, thus allowing the light from a lighthouse equipped with one to be visible over greater distances.
The Fresnel lens reduces the amount of material required compared to a conventional lens by dividing the lens into a set of concentric annular sections. An ideal Fresnel lens would have an infinite number of sections. In each section, the overall thickness is decreased compared to an equivalent simple lens. This effectively divides the continuous surface of a standard lens into a set of surfaces of the same curvature, with stepwise discontinuities between them.
In some lenses, the curved surfaces are replaced with flat surfaces, with a different angle in each section. Such a lens can be regarded as an array of prisms arranged in a circular fashion, with steeper prisms on the edges, and a flat or slightly convex center. In the first (and largest) Fresnel lenses, each section was actually a separate prism. 'Single-piece' Fresnel lenses were later produced, being used for automobile headlamps, brake, parking, and turn signal lenses, and so on. In modern times, computer-controlled milling equipment (CNC) might be used to manufacture more complex lenses.