Lens (Encyclopedia of Science)
Lenses are carefully shaped pieces of glass, plastic, or other transparent material. They are designed to manipulate light rays to create particular kinds of images. For example, the lenses in a telescope are designed to produce an enlarged view of a faraway object. Other common form of lenses are those found in eyeglasses, cameras, and microscopes.
Pioneers in lens development
Italian scientist Galileo Galilei (1564642) and Dutch scientist Antoni van Leeuwenhoek (1632723) were among the first to use lenses extensively in scientific research. Other scientistsrench mathematician René Descartes (pronounced ren-AY day-KART; 1596650) and English scientist Isaac Newton (1642727), among othersedicated most of their lives to improving lens designs. Despite the amount of time it has been in existence, the lens remains one of the simplest and most useful optical tools available.
How lenses work
Lenses work on two principles: that light always travels in straight lines, and that it travels more slowly through glass or plastic than it does through air.
Light bends when it exits one substance (the air) and enters another (a lens). It bends again as it leaves the lens. The amount of bending depends greatly upon how much the lens is curved. All lenses have at least one curved surface, and most have two....
(The entire section is 557 words.)
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