A basic principle of optics, that no passive optical system can increase the quantity L / n 2 , where L is the radiance of a beam and n is the local refractive index . ( 188 ) Note: "Conservation of radiance" was formerly called "conservation of brightness " or the "brightness theorem."
CONSERVATION OF RADIANCE
Meaning of CONSERVATION OF RADIANCE in English
Telecommunication standard terms English vocab. Английский словарь стандартных телекоммуникационных терминов. 2012