Guide to Units
The table below lists the quantities, units and notation used in radiometry and photometry.
|
Quantity |
Notation |
Unit |
|
Solid Angle |
W |
steradian (sr) |
|
Wavelength |
l |
nanometer (nm) = 10-9 meters |
|
Radiant Flux |
Fe |
Watt (W) |
|
Radiance |
Le |
Watt per steradian per sq. meter (W sr-1 m-2) |
|
Radiant Intensity |
Ie |
Watt per steradian (W sr-1) |
|
Irradiance |
Ee |
Watt per sq. meter (W m-2) |
|
Radiant Exitance |
Me |
Watt per sq. meter (W m-2) |
|
Luminous Flux |
Fv |
lumen (lm) |
|
Luminance |
Lv |
candela per sq. meter (cd m-2) = lumens per steradian per sq. meter (lm sr-1 m-2) = nit |
|
Luminous Intensity |
Iv |
candela (cd) = lumen per steradian (lm sr-1) |
|
Illuminance |
Ev |
lux = lumen per sq. meter (lm m-2) |
|
Luminous Exitance |
Mv |
lumen per sq. meter (lm m-2) |
|
Luminous Energy |
Qv |
lumen second (lm s) = Talbot |
|
Luminous Exposure |
Hv |
lux second (lx s) |