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Article: lens
- Article from:
- The Columbia Encyclopedia, Sixth Edition
CopyrightThe Columbia Encyclopedia, Sixth Edition. Copyright 2008 Columbia University Press. (Hide copyright information)
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lens device for forming an
image
of an object by the
refraction
of light. In its simplest form it is a disk of transparent substance, commonly glass, with its two surfaces curved or with one surface plane and the other curved. Lenses are used singly or in groups in such instruments as
cameras
, projectors,
microscopes
,
telescopes
,
binoculars
, opera glasses, and
eyeglasses
. The lens of the
eye
is known as a crystalline lens.
Classification of Lenses
All rays of light passing through a lens are refracted (bent) except those that pass directly through a point called the optical center. Lenses are classified according to the way in which they bend the rays of light ...