Optics. a unit of measure of the refractive power of a lens, having the dimension of the reciprocal of length and a unit equal to the reciprocal of one meter.
Abbreviation: D.
2.
an instrument, invented by Hipparchus, to measure the apparent diameter of the sun or moon or to estimate the size or elevation of distant objects.
Also, especially British, dioptre.
Origin
1585-95; < Latindioptra < Greek: instrument for measuring height or levels, equivalent to di-di-3 + op- (for ópsesthai to see) + -tra noun suffix of means
Related forms
dioptral, adjective
Examples from the web for diopter
The higher the diopter value, the higher the magnification.
The mirror was rough ground about a diopter out of spec.
From each plot center a three-diopter prism plot was established.
The diopter is often part of the right-hand eyepiece on a binocular.
British Dictionary definitions for diopter
dioptre
/daɪˈɒptə/
noun
1.
a unit for measuring the refractive power of a lens: the reciprocal of the focal length of the lens expressed in metres
Derived Forms
dioptral, adjective
Word Origin
C16: from Latin dioptra optical instrument, from Greek, from dia- through + opsesthai to see
diopter in Medicine
diopter di·op·ter (dī-ŏp'tər) n. Abbr. D. A unit of measurement of the refractive power of lenses equal to the reciprocal of the focal length measured in meters.