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A Fresnel lens ( / ˈfreɪnɛl, - nəl / FRAY-nel, -nəl; / ˈfrɛnɛl, - əl / FREN-el, -əl; or / freɪˈnɛl / fray-NEL[ 1]) is a type of composite compact lens which reduces the amount of material required compared to a conventional lens by dividing the lens into a set of concentric annular sections.
Augustin-Jean Fresnel. Augustin-Jean Fresnel[ Note 1] (10 May 1788 – 14 July 1827) was a French civil engineer and physicist whose research in optics led to the almost unanimous acceptance of the wave theory of light, excluding any remnant of Newton 's corpuscular theory, from the late 1830s [ 3] until the end of the 19th century. He is ...
The lens was installed in the lantern room of the new tower in Chicago, where it remained for nearly 100 years. [16] Also displayed at the fair was a hyperradiant Fresnel lens – the largest size ever made, "off the chart" of sixth through first Order. This lens was on hand when it was decided to build and outfit the Makapuʻu Point Light.
1859 – The Bodie Island Lighthouse had deteriorated and the Lighthouse Board secured a $25,000 appropriation from Congress to erect a new tower. This new tower was 80 ft (24 m). and its lantern was a third-order Fresnel lens. 1861 – In the fall of 1861, Confederate troops stacked explosives inside the tower and blew it apart.
Fresnel equations. Partial transmission and reflection of a pulse travelling from a low to a high refractive index medium. At near-grazing incidence, media interfaces appear mirror-like especially due to reflection of the s polarization, despite being poor reflectors at normal incidence. Polarized sunglasses block the s polarization, greatly ...
A Fresnel with the lens open to show the ridges. There is no lamp in the instrument. A Fresnel lantern (pronounced frəˈnɛl or fruh-nel) is a common lantern used in theatre that employs a Fresnel lens to wash light over an area of the stage. The lens produces a wider, soft-edged beam than a spotlight or key light, and is commonly used for ...
Klieg light. A Klieg light is an intense carbon arc lamp especially used in filmmaking. It is named after inventor John Kliegl and his brother Anton Kliegl. Klieg lights usually have a Fresnel lens with a spherical reflector or an ellipsoidal reflector with a lens train containing two plano-convex lenses or a single step lens.
The Fresnel number is a useful concept in physical optics. The Fresnel number establishes a coarse criterion to define the near and far field approximations. Essentially, if Fresnel number is small – less than roughly 1 – the beam is said to be in the far field. If Fresnel number is larger than 1, the beam is said to be near field.