In modern usage, diopter or dioptre is a measure of the refractive power of an optical system.

Look up diopter in Wiktionary, the free dictionary.

Diopter may also refer to:

• Historically, a dioptric lens
• Any lens system, such as a telescope
• A diopter sight
• A close-up lens used in photography
• A theodolite or similar surveyor's angle measuring device
• A dioptra, an old surveying device
• An alidade
• A surgical speculum
• An instrument for drawing the skull by projections

• Dioptrice
• Dioptrics

This disambiguation page lists articles associated with the title Diopter.
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