Photometric Units
Photometric Units
SI Units
Quantity |
|
|
Unit |
|
Luminous flux |
|
lumen |
|
lm |
Luminous intensity |
|
candela |
|
cd
|
Luminance |
|
cd/m2 |
|
|
Illuminance |
|
lm/m2 |
|
lx |
Non-SI Units
Luminous Intensity
|
candlepower = the candela |
|
Luminance
|
1 stilb = 1 cd/cm2 = 10,000 cd/m2 |
1 apostilb = (1/π) cd/m2 = 0.3183 cd/m2 |
1 lambert = (10,000/π) cd/m2 = 3183 cd/m2 |
1 millilambert = 0.001 lambert = 3.183 cd/m2 |
1 footlambert = (1/π) cd/ft2 = 3.426 cd/m2 |
1 candela/ft2 = 10.76 cd/m2 |
1 candela/in.2 = 1550 cd/m2 |
|
Illuminance
|
|
1 footcandle = 1 lm/ft2 = 10.76 lm/m2 or lx
|
Glossary
- illuminance
- Luminous flux incident per unit area of a surface; luminous incidence. (The use of the term "illumination" for this quantity conflicts with its more general meaning.)
- intensity
- Flux per unit solid angle.
illuminanceintensityphotometric unitsGeneral Reference