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Definition of LENS
a: a piece of transparent material (as glass) that has two opposite regular surfaces either both curved or one curved and the other plane and that is used either singly or combined in an optical instrument for forming an image by focusing rays of light
: a curved piece of glass or plastic used singly or combined in eyeglasses or an optical instrument (as a microscope) for forming an image by focusing rays of light
: a device for directing or focusing radiation other than light (as sound waves, radio microwaves, or electrons)
: a highly transparent biconvex lens-shaped or nearly spherical body in the eye that focuses light rays entering the eye typically onto the retina, lies immediately behind the pupil, is made up of slender curved rod-shaped ectodermal cells in concentric lamellae surrounded by a tenuous mesoblastic capsule, and alters its focal length by becoming more or less spherical in response to the action of the ciliary muscle on a peripheral suspensory ligament
Variants of LENS
Illustration of LENS
Piece of glass or other transparent substance that is used to form an image of an object by converging or diverging rays of light from the object. Because of the curvature of its surface, different rays of light are refracted (seerefraction) through different angles. A convex lens causes rays to converge on a single point, the focal point. A concave lens causes rays to diverge as though they are coming from a focal point. Both types cause the rays to form a visual image of the object. The image may be realinverted and photographable or visible on a screenor it may be virtualerect and visible only by looking through the lens.