PHOTON LUMINANCE
Definition
A <PHOTON LUMINANCE> is a <Property> that is, at a point on a surfact and in a given direction, the proton intensity dI_p of an element of that surface, divided by an <AREA> dA of the orthogonal projection of this element on a plane perpendicular to the given direction, thus L_p = dI_p /dA. Defined in ISO 80000-7 (2008) 7-52