Lambert (unit)

Template:Short description The lambert (symbol L) is a non-SI metric unit of luminance named for Johann Heinrich Lambert (1728–1777), a Swiss mathematician, physicist and astronomer. A related unit of luminance, the foot-lambert, is used in the lighting, cinema and flight simulation industries. The SI unit is the candela per square metre (cd/m²).

Definition

1 lambert (L) = $\frac{1}{\pi }$ candela per square centimetre (0.3183 cd/cm²) or $\frac{10^4}{\pi }$ cd m⁻² Template:Luminance conversions

See also

Other units of luminance:

• Apostilb (asb)
• Blondel (blondel)
• Bril (bril)
• Nit (nit)
• Stilb (sb)
• Skot (sk)

Template:Resize

Quantity		Unit		Dimension	Notes
Name	Symbol	Name	Symbol
Luminous energy	Template:Math	lumen second	lm⋅s	T⋅J	The lumen second is sometimes called the talbot.
Luminous flux, luminous power	Template:Math	lumen (= candela steradian)	lm (= cd⋅sr)	J	Luminous energy per unit time
Luminous intensity	Template:Math	candela (= lumen per steradian)	cd (= lm/sr)	J	Luminous flux per unit solid angle
Luminance	Template:Math	candela per square metre	cd/m2 (= lm/(sr⋅m2))	L−2⋅J	Luminous flux per unit solid angle per unit projected source area. The candela per square metre is sometimes called the nit.
Illuminance	Template:Math	lux (= lumen per square metre)	lx (= lm/m2)	L−2⋅J	Luminous flux incident on a surface
Luminous exitance, luminous emittance	Template:Math	lumen per square metre	lm/m2	L−2⋅J	Luminous flux emitted from a surface
Luminous exposure	Template:Math	lux second	lx⋅s	L−2⋅T⋅J	Time-integrated illuminance
Luminous energy density	Template:Math	lumen second per cubic metre	lm⋅s/m3	L−3⋅T⋅J
Luminous efficacy (of radiation)	Template:Math	lumen per watt	lm/W	M−1⋅L−2⋅T3⋅J	Ratio of luminous flux to radiant flux
Luminous efficacy (of a source)	Template:Mvar	lumen per watt	lm/W	M−1⋅L−2⋅T3⋅J	Ratio of luminous flux to power consumption
Luminous efficiency, luminous coefficient	Template:Mvar			1	Luminous efficacy normalized by the maximum possible efficacy
See also: Template:Hlist

References

• "Lighting Design Glossary: Luminance" at Schorsch Lighting Design Knowledgebase