photics
/ˈfəʊtɪks/rare
noun
The branch of science concerned with the properties and phenomena of light (distinguished from optics when that term is used in relation to sight). Formerly also: (collect. plural) †devices and apparatus for providing illumination ( obsolete ).
Origin
Mid 19th century; earliest use found in Robert Mayne (1808–1868). From photic: see -ic.