The science of radiation measurement. See Table of Radiometric Terms.
TABLE OF RADIOMETRIC TERMS
Term Symbol Quantity Unit
radiant energy Q energy joule (J)
radiant power Synonym optical power power watt (W)
irradiance E power incident per unit area (irrespective of angle) W•m -2
spectral irradiance E irradiance per unit wavelength interval at a given wavelength W•m -2 •nm -1
radiant emittance Synonym radiant exitance W power emitted (into a full sphere) per unit area W•m -2
radiant intensity I power per unit solid angle W•sr -1
radiance L power per unit angle per unit projected area W•sr -1 •m -2
spectral radiance L radiance per unit wavelength interval at a given wavelength W•sr -1 •m -2 •nm -1