Most typically utilized in light-gathering applications, a Fresnel lens is a compact lens originally developed by French physicist Augustin-Jean Fresnel for lighthouses. These lenses are lightweight and available in myriad sizes, provide ideal light gathering capabilities and are made of plastic. You most typically find a Fresnel lens in condenser systems or detector/emitter operations. Fresnel lenses are also found providing magnification in projection lenses and in illumination devices.
Lighthouse Lens
With a Fresnel lens, the conventional optical lens is replaced; the contours of a Fresnel lens are better able to individually refract surfaces, bend parallel light rays and focus them into a common focal length. The benefit of using a Fresnel lens is that – even though they are physically more narrow than other lenses – they can focus light much the same as a conventional optic lens, but in a smaller, thinner model. These lenses do not scatter light across a medium which means most of the material in the center of the lens will increase the absorption and weight within the object being viewed.
The idea for the Fresnel lens was first developed in the 18th century as a way to create annular rings and a curved profile. This profile would then form a conventional curved lens. The “high groove intensity” allows for better focusing performance and higher quality images being captured as compared to standard lenses.
The way the first Fresnel lenses were manufactured was through a protracted grinding of, then polishing of, the glass by hand. The process progressed to pouring of molten glass into molds to the development, in the 20th century, of injection molding of optical quality plastics; these advances have now made the Fresnel lens more practical for commercial applications.
What is a Fresnel lens used for?
- To collect and collimate the point of light source by placing it one focal length away from the source.
- The collection of solar light to concentrate it onto a photovoltaic cell or as a way to heat a surface. A Fresnel lens can be found in homes that use solar power to heat the home or a swimming pool.
- In magnifiers or projection lenses, although the quality of these lenses – in this setting – doesn’t provide the higher precision as compared to the amount of distortion noted.