radiometry, radiantflux or radiant power is the radiant energy emitted, reflected, transmitted, or received per unit time, and spectral flux or spectral
radiometry, radiant intensity is the radiantflux emitted, reflected, transmitted or received, per unit solid angle, and spectral intensity is the radiant intensity
calculated by integrating radiantflux (or power) with respect to time. The symbol Qe is often used throughout literature to denote radiant energy ("e" for "energetic"
radiometry, irradiance is the radiantflux received by a surface per unit area. The SI unit of irradiance is the watt per square metre (W⋅m−2). The CGS unit erg
Alternative symbols sometimes seen: W or E for radiant energy, P or F for radiantflux, I for irradiance, W for radiant exitance. Spectral quantities given