In optics the noise-equivalent flux density (NEFD) or noise-equivalent irradiance (NEI) of a system is the level of flux density required to be equivalent to the noise present in the system. It is a measure used by astronomers in determining the accuracy of observations.
Famous quotes containing the word flux:
“Death not merely ends life, it also bestows upon it a silent completeness, snatched from the hazardous flux to which all things human are subject.”
—Hannah Arendt (1906–1975)