Fresnel lens

Optics. a large lens with a surface of concentric grooves of prismatic profile, used in automobile headlights, searchlights, spotlights, etc.
[1840-50; see FRESNEL]

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Series of concentric rings, each consisting of a thin part of a simple lens, assembled on a flat surface.

G.-L.-L. Buffon (1748) first had the idea of dividing a lens surface into concentric rings to reduce the weight. In 1820 his idea was adopted by Augustin-Jean Fresnel (1788–1827) for the construction of lighthouse lenses. Fresnel lenses have the optical properties of much thicker and heavier lenses. They are used in spotlights, floodlights, railroad and traffic signals, and decorative lights. Some thin Fresnel lenses are molded in plastic, the width of the rings being only a few thousandths of an inch; such lenses are used in cameras and small projectors.

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 succession of concentric rings, each consisting of an element of a simple lens, assembled in proper relationship on a flat surface to provide a short focal length (see illustration—>). The Fresnel lens is used particularly in lighthouses and searchlights (searchlight) to concentrate the light into a relatively narrow beam. It would be almost impossible to make a large lighthouse lens of the usual solid glass-disk type because the thickness and weight would be prohibitive; the lighter Fresnel lens is constructed of elements that are separately ground and polished from suitable glass blanks and assembled to make up the complete lens.

      A one-piece molded-glass Fresnel lens is convenient for spotlights (spotlight), floodlights, railroad and traffic signals, and decorative lights in buildings. Cylindrical Fresnel lenses are used in shipboard lanterns (lantern) to increase visibility.

      A wide variety of thin Fresnel lenses are molded in plastic, the width of the rings being only a few thousandths of an inch, for use as field lenses with ground-glass screens in cameras and small projectors to increase the brightness of the outer parts of the screen.

      Georges-Louis Leclerc (Buffon, Georges-Louis Leclerc, count de) de Buffon (1748) originated the idea of dividing a lens surface into concentric rings in order to reduce the weight significantly. In 1820 this idea was adopted by Augustin-Jean Fresnel in the construction of lighthouse lenses.

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Universalium. 2010.

Look at other dictionaries:

  • Fresnel lens — Lens Lens (l[e^]nz), n.; pl. {Lenses} ( [e^]z). [L. lens a lentil. So named from the resemblance in shape of a double convex lens to the seed of a lentil. Cf. {Lentil}.] (Opt.) A piece of glass, or other transparent substance, ground with two… …   The Collaborative International Dictionary of English

  • Fresnel lens — Fres nel lens [See {Fresnel lamp}.] (Optics) See under {Lens}. [1913 Webster] …   The Collaborative International Dictionary of English

  • Fresnel lens — n. [after FRESNEL Augustin Jean] a thin optical lens of many concentric rings, having the properties of a much thicker and heavier lens: used in cameras, lighthouse beacons, etc …   English World dictionary

  • Fresnel lens — A Fresnel lens (pronounced [ frɛz.nəl] or [freɪ nɛl] ) is a type of lens invented by French physicist Augustin Jean Fresnel. Originally developed for lighthouses, the design enables the construction of lenses of large aperture and short focal… …   Wikipedia

  • Fresnel lens — noun lens composed of a number of small lenses arranged to make a lightweight lens of large diameter and short focal length • Hypernyms: ↑lens, ↑lense, ↑lens system • Part Holonyms: ↑headlight, ↑headlamp, ↑searchlight * * * …   Useful english dictionary

  • Fresnel lens — noun Etymology: Augustin J. Fresnel Date: 1865 a lens that has a surface consisting of a concentric series of simple lens sections so that a thin lens with a short focal length and large diameter is possible and that is used especially for… …   New Collegiate Dictionary

  • Fresnel lens — /frənɛl ˈlɛns/ (say fruhnel lens) noun a large lens with a short focal length, used in headlights, spotlights, etc. {See Fresnel diffraction} …   Australian English dictionary

  • Fresnel lens — Fres·nel lens (fra nelґ) [Augustin Jean Fresnel, French physicist and engineer, 1788–1827] see under lens …   Medical dictionary

  • fresnel lens — [freɪ nɛl] noun Photography a flat lens made of a number of concentric rings, to reduce spherical aberration. Origin C19: named after the French physicist and civil engineer Augustin J. Fresnel …   English new terms dictionary

  • fresnel lens — F/A/V a flat glass or acrylic lens in which the curvature of a normal lens surface has been collapsed in such a way that concentric circles are impressed on the lens surface; often used for the condenser lens in overhead projectors, in rear… …   Audio and video glossary

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