# 17-21-058

Ep; E

density of incident photon flux with respect to area at a point on a real or imaginary surface

where Φp is photon flux and A is the area on which the photon flux is incident

Note 1 to entry: The corresponding radiometric quantity is "irradiance". The corresponding photometric quantity is "illuminance".

Note 2 to entry: The photon irradiance is expressed in second to the power minus one per square metre (s−1·m−2).

Note 3 to entry: This entry was numbered 845-01-39 in IEC 60050-845:1987.

Note 4 to entry: This entry was numbered 17-929 in CIE S 017:2011.

Publication date: 2020-12