# Brilliance

the brilliance L (English. luminance) is the photo-metric measure for brightness. A source of light appears thus all the brighter, the smaller their surface in the comparison to luminous intensity to I is. The brilliance is what humans notice as brightness.

## definition

with the brilliance concerns it the relationship of radiated luminous intensity I and the quantity Atheir apparent bright surface. The brilliance has the unit candela per meter ² and/or. cd/m ². It is photo-metric correspondence to the radiation intensity L (λ) (unit: Watt·Meter of -2·Steradiant -1 and/or. W·m -2·SR -1) of the radiometry.One does not see perpendicular on the radiating surface, only its projection is effective (angles θ).

[itex] L= \ frac {\ mathrm {D} I} {\ mathrm {D} A \ cos (\ theta)} = \ frac {\ mathrm {d^ {2}} \ Phi} {\ mathrm {D} A \ cos (\ theta) \ mathrm {D} \ omega}< /math>

## characteristic shining densities

### brightness of the sky

• of middle ones clear sky: 8000 cd/m ²
• middle ones covered sky: 2000 cd/m ²
• Night sky with full moon: 0,1 cd/m ²
• star-clear night sky: 0,001 cd/m ²
• cloudy night sky: 1… 100 · 10 -6 cd/m ²
• perception border: 3 · 10 -6 cd/m ²

### Flächenhelligkeit of emitters

• sun disk at noon: 1600 · 10 6 cd/m ²
• sun disk on the horizon: 6· 10 6 cd/m ²
• mat bulb 60 W: 120 · 10 3 cd/m ²
• T8 cold-white fluorescence tube: 11 · 10 3 cd/m ²
• surface of the moon: 2,5 · 10 3 cd/m ²
• the Greens elektrolumineszente source of light: 30 cd/m ²

## units

into that The USA are the units Lambert and/or. the name of rivet for candelas per square meter common.

Older units of the brilliance are among other things:

• Rivet: 1 NT = 1 cd/m ²
• Stilb: 1 self-service = 1 cd/cm ² = 10,000 cd/m ²
• candelas per square foot: 1 cd/ft ² = approx.10,764 cd/m ²
• candelas per square tariff: 1 cd/in ² = approx. 1.550 cd/m ²
• Apostilb, Blondel: 1 asb = 1 blondel = 1/π · 10 -4 self-service = 1/π cd/m ²
• Skot: 1 skot =0,001 blondel = 0.001 asb = 10 -3/π cd/m ²
• Lambert: 1 la = 1 L = 10/π cd/m ² = approx. 3,183 cd/m ²
• Footlambert: 1 flat steel bar = 1/π cd/ft ² = approx. 3,426 cd/m ²