PHOTOMETRY
photometry
(noun) measurement of the properties of light (especially luminous intensity)
Source: WordNet® 3.1
Etymology
Noun
photometry (usually uncountable, plural photometries)
(physics) The measurement of various aspects of light, especially its intensity.
(astronomy) The measurement of the intensity and spectrum of light from stars.
Source: Wiktionary
Pho*tom"e*try, n. Etym: [Cf. F. photométrie.]
Definition: That branch of science which treats of the measurement of the
intensity of light.
Source: Webster’s Unabridged Dictionary 1913 Edition