luminous flux

Of a source of luminous intensityI in an element of solid angled Ω is given by d Φ = I d Ω.
Source:
Green Book, 2nd ed., p. 72
PAC, 1996, 68, 957 (Glossary of terms in quantities and units in Clinical Chemistry (IUPAC-IFCC Recommendations 1996)) on page 979