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Light rays converge when passing through a biconvex lens (top) and diverge when passing through a biconcave lens (bottom).f indicates the focus.


n. pl. lens·es
1. A ground or molded piece of glass, plastic, or other transparent material with opposite surfaces either or both of which are curved, by means of which light rays are refracted so that they converge or diverge to form an image.
2. A combination of two or more such pieces, sometimes with other optical devices such as prisms, used to form an image for viewing or photographing. Also called compound lens.
3. A thin piece of glass or plastic, as on a pair of sunglasses, that transmits light without refraction.
4. A device or phenomenon (such as a gravitational field) that causes light or other radiation to converge or diverge by an action analogous to that of a lens.
a. A transparent, biconvex structure in the eye of a vertebrate or cephalopod that is located between the iris and the vitreous humor and focuses light rays entering through the pupil to form an image on the retina.
b. A similar structure in many invertebrates.
tr.v. lensed, lens·ing, lens·es
1. Informal To make a photograph or movie of.
2. To bend or distort (light, for example) by means of a lens, especially a gravitational field.

[New Latin lēns, from Latin, lentil (from the shape of a double convex lens).]

lensed adj.
American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.


materials which colour and diffuse light
Collins English Dictionary – Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014
References in periodicals archive ?
To minimize the blurring caused by Earth's atmosphere, many astronomers use radio telescopes to search for gravitational lensing. In their ongoing study, Wilkinson and his colleagues rely on several instruments, including the Very Large Array near Socorro, N.M., and the MERLIN network of radio telescopes spread across England, to examine thousands of distant galaxies.
They note, for example, that the object believed to be a massive foreground galaxy lies at the center of the arc's curve--just where a lensing galaxy should reside.
Examining a distant cluster of galaxies, the Hubble Space Telescope has produced the sharpest picture ever of a cosmic mirage called gravitational lensing. Researchers say that as Hubble takes more of these high-resolution images, they will yield a more accurate estimate of the universe's dark matter -- material that can't be observed like ordinary matter.