Lens (optics)

Article By:

Baird, Christopher S. Department of Chemistry and Physics, West Texas A&M University, Canyon, Texas.

Last reviewed:March 2022

DOI:https://doi.org/10.1036/1097-8542.377000

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• Lens (optics), published January 2020:Download PDF Get Adobe Acrobat Reader

A transparent object that uses refraction in order to alter the light that passes through the object. In general, when a ray of light crosses the interface between two different transparent materials, the ray experiences a bending of its path. This effect is called refraction (Fig. 1). The amount of bending depends on the materials involved and on the angle at which the light meets the interface. A traditional lens is made of glass, plastic, or crystal and is surrounded by air. The overall effect of a lens on a particular light ray that passes through it is a combination of the refraction that the ray experiences when entering the front surface of the lens and the refraction it experiences when exiting the back surface of the lens. Carefully choosing the shape of the back and front surfaces of a lens allows the lens designer to choose the angle at which each ray meets each surface, and therefore choose how much each ray is bent. In this way, a lens is an effective way to control light. See also: Air; Crystal; Glass; Light; Optics; Polymer; Refraction of waves

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