\Di*op"trics\, n. [Gr. ? ?: cf. F. dioptrique.]
(Optics)
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.