: a branch of optics that deals with those phenomena of reflection and refraction that can be mathematically deduced from simple empirical laws
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the branch of optics dealing with light as rays, esp. in the study of the effects of lenses and mirrors on light beams and of their combination in optical instruments.
[1830-40]
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geometrical optics,
the branch of optics that deals with the formation and structure of images, using geometric methods of description.
Useful english dictionary. 2012.