DIOPTRE
Di*op"tre, n. Etym: [F. See 2d Dioptric.] (Optics)
Defn: A unit employed by oculists in numbering glasses according to the metric system; a refractive power equal to that of a glass whose principal focal distance is one meter.
DIOPTRIC
Di*op"tric, a. (Optics)
Defn: Of or pertaining to the dioptre, or to the metric system of numbering glasses. — n.
Defn: A dioptre. See Dioptre.
DIOPTRIC; DIOPTRICAL
Di*op"tric, Di*op"tric*al, a. Etym: [Gr. dioptrique.]
Defn: Of or pertaining to dioptrics; assisting vision by means of the refraction of light; refractive; as, the dioptric system; a dioptric glass or telescope. "Dioptrical principles." Nichol. Dioptric curve (Geom.), a Cartesian oval. See under Cartesian.
DIOPTRICS
Di*op"trics, n. Etym: [Gr. dioptrique.] (Optics)
Defn: The science of the refraction of light; that part of geometrical optics which treats of the laws of the refraction of light in passing from one medium into another, or through different mediums, as air, water, or glass, and esp. through different lenses; — distinguished from catoptrics, which refers to reflected light.
DIOPTRY
Di*op"try, n. (Optics)