You searched for: “luminous flux
luminous flux (s) (noun) (usually not plural)
The rate of flow of radiant energy, expressed by brightness that is emitted in a unit of solid angles by a uniform point source with intensities of one candela or the base unit of beaming intensity or the power emitted by a source of illumination: Dr. Young and the scientists measured the luminous flux using the latest equipment designed to indicate in lumen the rate or speed of light transmission.