Note 1 to entry: The output can be electrical, e.g. current, voltage or a change in resistance, or chemical, e.g. in a photographic film or an actinometer, or mechanical, e.g. in a Golay detector.
Note 2 to entry: This entry was numbered 845-05-51 in IEC 60050-845:1987.
Note 3 to entry: This entry was numbered 17-856 in CIE S 017:2011.