illuminance, \(E\), \(E_{\text{v}}\)

https://doi.org/10.1351/goldbook.I02941
luminous flux received by a surface divided by the area of that surface.
Sources:
Green Book, 2nd ed., p. 72 (https://dev.goldbook.iupac.org/files/pdf/green_book_2ed.pdf)
PAC, 1996, 68, 957. 'Glossary of terms in quantities and units in Clinical Chemistry (IUPAC-IFCC Recommendations 1996)' on page 976 (https://doi.org/10.1351/pac199668040957)