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."
... formed in 1983.
The initial members were the United Kingdom, France, Germany, Italy and Spain.
In 1985 France withdrew in favour of the 100% French Avions de Combat ...