Meaning of LENS in English
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 (see refraction ) 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 real
inverted and photographable or visible on a screen
or it may be virtual
erect and visible only by looking through the lens.
Britannica Concise Encyclopedia. Краткая энциклопедия Британика. 2012