Basic Illumination Definitions

1. Irradiance(辐照度)

total amount of energy received per unit area of a surface

 

2. Illuminance(照明度)

essentially same as irradiance,the difference is that illuminance measures the amount of visible light energy in photometric terms

 

3. Radiance(辐射)

measure of energy that is reflected by the surface

 

4. Luminance(亮度)

measure of photometrically weighted light energy that leaves the surface

 

5. Luminous intensity

amount of light energy that is emitted by the surface in a given direction