Radiant Intensity is a measure of the intensity of electromagnetic radiation. It is defined as power per unit solid angle.
Applicable units are those of quantitykind:RadiantIntensity
http://en.wikipedia.org/wiki/Radiant_intensity
https://cdd.iec.ch/cdd/iec61987/iec61987.nsf/ListsOfUnitsAllVersions/0112-2---62720%23UAD151
Radiant Intensity is a measure of the intensity of electromagnetic radiation. It is defined as power per unit solid angle.
$I = \frac{d\Phi}{d\Omega}$, where $d\Phi$ is the radiant flux leaving the source in an elementary cone containing the given direction with the solid angle $d\Omega$.