| Bezeichnung | Formelzeichen | Definition | Einheitenname | Einheitenumformung | Dimension |
|---|---|---|---|---|---|
| Lichtstrom (luminous flux, luminous power) |
$ \textstyle {\mathit {\Phi _{\mathrm {v} }}}\,,F\,,P $ | $ \textstyle {\mathit {\Phi _{\mathrm {v} }}}=K_{\mathrm {m} }\int _{380\,\mathrm {nm} }^{780\,\mathrm {nm} }{\frac {\partial {\mathit {\Phi _{\mathrm {e} }}}(\lambda )}{\partial \lambda }}\cdot V(\lambda )\,\mathrm {d} \lambda $ | Lumen (lm) | $ \textstyle \mathrm {1\,lm=1\,sr\cdot cd} $ | $ {\mathsf {J}}\, $ |
| Beleuchtungsstärke (illuminance) |
$ \textstyle E_{\mathrm {v} }\, $ | $ \textstyle E_{\mathrm {v} }={\frac {\partial {\mathit {\Phi _{\mathrm {v} }}}}{\partial A}} $ | Lux (lx), früher Nox (nx), Phot (ph) | $ \textstyle \mathrm {1\,lx=1\,{\frac {lm}{m^{2}}}=1\,{\frac {sr\cdot cd}{m^{2}}}} $ | $ {\mathsf {L^{-2}\cdot J}} $ |
| Spezifische Lichtausstrahlung (luminous emittance) |
$ \textstyle M_{\mathrm {v} }\, $ | $ \textstyle M_{\mathrm {v} }={\frac {\partial {\mathit {\Phi _{\mathrm {v} }}}}{\partial A}} $ | Lux (lx) | $ \textstyle \mathrm {1\,lx=1\,{\frac {lm}{m^{2}}}=1\,{\frac {sr\cdot cd}{m^{2}}}} $ | $ {\mathsf {L^{-2}\cdot J}} $ |
| Leuchtdichte (luminance) |
$ \textstyle L_{\mathrm {v} }\, $ | $ \textstyle L_{\mathrm {v} }={\frac {\partial ^{2}{\mathit {\Phi _{\mathrm {v} }}}}{\partial \Omega \cdot \partial A_{1}\cdot \cos \varepsilon _{1}}} $ | keine eigene Einheit, manchmal Nit genannt, früher in Stilb (sb), Apostilb (asb), Lambert (la), Blondel |
$ \textstyle \mathrm {1\,{\frac {cd}{m^{2}}}=1\,{\frac {lm}{sr\cdot m^{2}}}} $ | $ {\mathsf {L^{-2}\cdot J}} $ |
| Lichtstärke (luminous intensity) |
$ \textstyle I_{\mathrm {v} }\, $ | $ \textstyle I_{\mathrm {v} }={\frac {\partial {\mathit {\Phi _{\mathrm {v} }}}}{\partial \Omega }} $ | Candela (cd) (SI-Basiseinheit), früher in Hefnerkerze (HK), Internationale Kerze (IK), Neue Kerze (NK) |
$ \textstyle \mathrm {1\,cd=1\,{\frac {lm}{sr}}} $ | $ {\mathsf {J}}\, $ |
| Lichtmenge (luminous energy) |
$ \textstyle Q_{\mathrm {v} }\, $ | $ \textstyle Q_{\mathrm {v} }=\int _{0}^{T}{\mathit {\Phi _{\mathrm {v} }}}(t)\mathrm {d} t $ | Lumensekunde (lm s), Talbot, Lumberg | $ \textstyle \mathrm {1\,lm\cdot s=1\,sr\cdot cd\cdot s} $ | $ {\mathsf {T\cdot J}} $ |
| Belichtung (luminous exposure) |
$ \textstyle H_{\mathrm {v} }\, $ | $ \textstyle H_{\mathrm {v} }=\int _{0}^{T}E_{\mathrm {v} }(t)\mathrm {d} t $ | Luxsekunde (lx s) | $ \textstyle \mathrm {1\,lx\cdot s=1\,{\frac {lm\cdot s}{m^{2}}}=1\,{\frac {sr\cdot cd\cdot s}{m^{2}}}} $ | $ {\mathsf {L^{-2}\cdot T\cdot J}} $ |
| Lichtausbeute (luminous efficacy) |
$ \textstyle \eta \,,\rho \, $ | $ \textstyle \eta ={\frac {\mathit {\Phi _{\mathrm {v} }}}{P}} $ | Lumen / Watt | $ \textstyle \mathrm {1\,{\frac {lm}{W}}=1\,{\frac {sr\cdot cd\cdot s}{J}}=1\,{\frac {sr\cdot cd\cdot s^{3}}{kg\cdot m^{2}}}} $ | $ {\mathsf {M^{-1}\cdot L^{-2}\cdot T{^{3}}\cdot J}} $ |
| Raumwinkel (solid angle) |
$ \textstyle \Omega \, $ | $ \textstyle \Omega ={\frac {S}{r^{2}}} $ | Steradiant (sr) | $ \textstyle \mathrm {1\,sr={\frac {\left[Fl{\ddot {a}}che\right]}{\left[Radius^{2}\right]}}=1\,{\frac {m^{2}}{m^{2}}}} $ | $ {\mathsf {1}}\, $ (Eins) |