Glossary term: Lens

Description: A lens is an optical device that, due to refraction, bends light so that it either focusses or disperses. Lenses are typically made from glass, plastic or some other transparent material. Convex lenses focus light, drawing a parallel beams of light together to a point. Concave lenses disperse light, spreading parallel beams of light out so that they travel away from each other. Lenses are the main components in refracting telescopes as well as binoculars. Even if an astronomical telescope is a relecting telescope (one that uses mirrors to focus light), it is likely that the cameras and spectrographs attached to the telescope will use one or more lenses.

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Term and definition status: This term and its definition is still awaiting approval

The OAE Multilingual Glossary is a project of the IAU Office of Astronomy for Education (OAE) in collaboration with the IAU Office of Astronomy Outreach (OAO). The terms and definitions were chosen, written and reviewed by a collective effort from the OAE, the OAE Centers and Nodes, the OAE National Astronomy Education Coordinators (NAECs) and other volunteers. You can find a full list of credits here. All glossary terms and their definitions are released under a Creative Commons CC BY-4.0 license and should be credited to "IAU OAE".