| Fresnel lantern | A lantern having a lamp surrounded by a hollow cylindrical Fresnel lens. Origin: From Fresnel the inventor, a French physicist. Source: Websters Dictionary (01 Mar 1998) |
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| aristotle's lantern | <zoology> The five united jaws and accessory ossicles of certain sea urchins. Source: Websters Dictionary (01 Mar 1998) |
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| lantern | 1. Something inclosing a light, and protecting it from wind, rain, etc.; sometimes portable, as a closed vessel or case of horn, perforated tin, glass, oiled paper, or other material, having a lamp or candle within; sometimes fixed, as the glazed inclosure of a street light, or of a lighthouse light. 2. An open structure of light material set upon a roof, to give light and air to the interior. A cage or open chamber of rich architecture, open below into the building or tower which it crowns. A smaller and secondary cupola crowning a larger one, for ornament, or to admit light; such as the lantern of the cupola of the Capitol at Washington, or that of the Florence cathedral. 3. <machinery> A lantern pinion or trundle wheel. See Lantern pinion (below). 4. <engineering> A kind of cage inserted in a stuffing box and surrounding a piston rod, to separate the packing into two parts and form a chamber between for the reception of steam, etc.; called also lantern brass. 5. A perforated barrel to form a core upon. 6. <zoology> See Aristotle's lantern. Fig. 1 represents a hand lantern; fig. 2, an arm lantern; fig. 3, a breast lantern; so named from the positions in which they are carried. Dark lantern, a lantern with a single opening, which may be closed so as to conceal the light; called also bull's-eye. Lantern fly, Lantern carrier, any translucent, marine, bivalve shell of the genus Anatina, and allied genera. Magic lantern, an optical instrument consisting of a case inclosing a light, and having suitable lenses in a lateral tube, for throwing upon a screen, in a darkened room or the like, greatly magnified pictures from slides placed in the focus of the outer lens. Origin: F. Lanterne, L. Lanterna, laterna, from Gr. Light, torch. See Lamp. Source: Websters Dictionary (01 Mar 1998) |
| Fresnel, Augustin Jean | <person> French physicist, 1788-1827. See: Fresnel lens, Fresnel prism. (05 Mar 2000) |
| Fresnel fringes | <microscopy> A class of diffraction fringes formed when the source of illumination and viewing screen are at a finite distance from a diffracting edge. In the electron microscope these fringes are best seen when the object is slightly out of focus. (05 Aug 1998) |
| Fresnel lens | <physics> A lens built up, progressively, in zones or steps, each zone with its own individual radius. Considerable spherical correction is attained, and the weight of the lens is greatly reduced. Fresnel lenses were originally designed for lighthouses but they are now attainable for small spotlights, automobile headlights, and similar uses. (05 Aug 1998) |
| Fresnel prism | A prism composed of concentric annular rings. (05 Mar 2000) |
| Fresnel reflection | <microscopy> Process by which radiant flux is reflected from an optically plane boundary between two transparent dielectric materials. (05 Aug 1998) |
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