Radiant exitance
AREAL DENSITY OF EXITING RADIANT FLUX
Radiant emittance; Exitance; Spectral radiant exitance; Photon exitance
In radiometry, radiant exitance or radiant emittance is the radiant flux emitted by a surface per unit area, whereas spectral exitance or spectral emittance is the radiant exitance of a surface per unit frequency or wavelength, depending on whether the spectrum is taken as a function of frequency or of wavelength. This is the emitted component of radiosity.