Measurements to determine the radiance of one portion of a nonuniform source can be strongly influenced by radiation from other portions of the source scattered by the optical system used to transmit the radiation to the detector. Conditions under which such scattering is important and procedures to correct for it are discussed. An illustration is provided from measurements made on a nitrogen arc source.
W. H. Venable, Jr., "Effects upon Radiant Intensity Measurements Due to Scattering by Optical Elements," Appl. Opt. 9, 609-615 (1970)