a unit of luminous exitance. The term “radlux” was derived from lux, a unit of illuminance with the same dimensional formula; it was proposed by the French physicist A. Blondel.

The radlux was introduced in the USSR in 1948 by The Statute on Photometric Units. It was defined as the luminous exitance that is the same at all points of a luminous plane surface and that emits a luminous flux in one direction of 1 lumen per sq m.

Radlux is abbreviated rlx. It was used rarely; the All-Union State Standard 7932–56, Photometric Units, replaced radlux with the unit lumen sq m (1 m/m2).


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