from The American Heritage® Dictionary of the English Language, 5th Edition.
- noun A thin optical lens consisting of concentric rings of segmental lenses and having a short focal length, used primarily in lighthouses, spotlights, overhead projectors, and the headlights of motor vehicles.
from the GNU version of the Collaborative International Dictionary of English.
- (Optics) See under
from Wiktionary, Creative Commons Attribution/Share-Alike License.
- noun The
hollow cylindrical lensused in the Fresnel lamp.
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- noun lens composed of a number of small lenses arranged to make a lightweight lens of large diameter and short focal length
from The American Heritage® Dictionary of the English Language, 4th Edition
[After Augustin Jean Fresnel.]
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