In telecommunication, a conservation of radiance is a basic principle of optics, that no passive optical system can increase the quantity L /n2, where L is the radiance[?] of a beam and n is the local refractive index.
Note:"Conservation of radiance" was formerly called "conservation of brightness" or the "brightness theorem."
... identical to Avestan, the language of Zoroastrianism. After the consolidation of its grammar and lexicon (see History below) it turned into a classical language of ...