from The American Heritage® Dictionary of the English Language, 4th Edition

  • n. A thin optical lens consisting of concentric rings of segmental lenses and having a short focal length, used primarily in spotlights, overhead projectors, and the headlights of motor vehicles.

from Wiktionary, Creative Commons Attribution/Share-Alike License

  • n. The hollow cylindrical lens used in the Fresnel lamp.

from the GNU version of the Collaborative International Dictionary of English

  • See under lens.
  • n. a compound lens formed by placing around a central convex lens rings of glass so curved as to have the same focus; used, especially in lighthouses, for concentrating light in a particular direction; -- so called from the inventor.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

  • n. lens composed of a number of small lenses arranged to make a lightweight lens of large diameter and short focal length


After Augustin Jean Fresnel.
(American Heritage® Dictionary of the English Language, Fourth Edition)


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