Definition of dioptre in English:

dioptre

Line breaks: di|optre
Pronunciation: /dʌɪˈɒptə
 
/
(US diopter)

noun

A unit of refractive power, which is equal to the reciprocal of the focal length (in metres) of a given lens: vision corrected to within one dioptre of perfect sight
More example sentences
  • The focusing power of a lens is measured in dioptres.
  • Refractive error is measured in dioptres, and myopia is designated with a minus sign.
  • The difference between the focusing powers of these two axes, measured in dioptres, is the astigmatism.

Origin

late 16th century (originally as diopter, denoting an alidade): from French, from Latin dioptra, from Greek, from di- 'through' + optos 'visible'. The term was used in the early 17th century to denote an ancient form of theodolite; the current sense dates from the late 19th century.

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