Diopter

noun

noun ·Rare ·Advanced level

Definitions

Noun
  1. 1
    A unit of measure of the power of a lens or mirror, equal to the reciprocal of its focal length in meters. Myopia is diagnosed and measured in diopters.
  2. 2
    a unit of measurement of the refractive power of a lens which is equal to the reciprocal of the focal length measured in meters; used by oculists wordnet
  3. 3
    The dioptre adjustment mechanism of a pair of binoculars or of a camera viewfinder.
  4. 4
    A lens element attached to the front of a photographic lens to shorten the lens's minimum focus distance; also called a "close-up filter". dated
  5. 5
    Any lens system, such as a telescope. obsolete
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  1. 6
    A theodolite or similar surveyor’s angle measuring device. obsolete
  2. 7
    An alidade. obsolete
  3. 8
    A surgical speculum. obsolete
  4. 9
    An instrument for drawing the skull by projections. obsolete

Synonyms

All synonyms
dioptrelens power unitreciprocal meterrefractive power unitunit of optical power

Etymology

From Latin dioptra, from Ancient Greek διόπτρα (dióptra).

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