candle per square foot (cd/ft²)
candela per square meter (cd/m²)
lumen per square centimeter (lm/cm²)
lumen per square meter (lm/m²)
In photometry, illuminance is the total luminous flux incident on a surface, per unit area. It is a measure of how much the incident light illuminates the surface, wavelength-weighted by the luminosity function to correlate with human brightness perception.