Stilb

Physical unit
Unit name	Stilb
Unit symbol	${\displaystyle \mathrm {sb} }$
Physical quantity (s)	Luminance
Formula symbol	${\displaystyle L}$
dimension	${\displaystyle {\mathsf {N\;L^{-2}}}}$
system	CGS system of units
In SI units	${\displaystyle \mathrm {1\,sb=10^{4}\;{\frac {cd}{m^{2}}}} }$
Named after	greek stilbein , "shiny"
Derived from	Candela , square meter
See also: Apostilb , Blondel

The stilb ( sb ) is an outdated unit of luminance in non-self-luminous bodies and has not been an official unit of measurement since January 1st, 1978 .

The word is derived from the Greek word stilbein (to shine) and was coined around 1920 by André-Eugène Blondel . While the North American region preferred more pictorial terms such as “ candles per square meter”, the Stilb remained in use in Europe until the Second World War .

The stilb corresponds - with one factor - to the SI unit cd / m² :

${\displaystyle {\begin{aligned}1\ \mathrm {sb} &:=1\ \mathrm {\frac {cd}{cm^{2}}} \\&=10^{4}\ \mathrm {\frac {cd}{m^{2}}} =10^{4}\,\mathrm {nt} =10^{7}\,\mathrm {Millinit} \\\Leftrightarrow 10^{-4}\ \mathrm {sb} &=1\ \mathrm {\frac {cd}{m^{2}}} \end{aligned}}}$

with for the nit . ${\displaystyle \mathrm {nt} }$

More conversions

The apostilb or blondel was used as a subunit for self-luminous bodies :

${\displaystyle {\begin{aligned}1\ \mathrm {asb} =1\mathrm {blondel} &=\mathrm {{\frac {1}{\pi }}{\frac {cd}{m^{2}}}} &&=\mathrm {{\frac {10^{-4}}{\pi }}\ sb} \\&\approx 0{,}31831\ \mathrm {\frac {cd}{m^{2}}} &&=10^{-4}\ \mathrm {la} \\&\approx 0{,}000031831\ \mathrm {\frac {cd}{cm^{2}}} &&=\mathrm {{\frac {10^{-4}}{\pi }}\ {\frac {cd}{cm^{2}}}} \\&\approx 0{,}000031831\ \mathrm {sb} \end{aligned}}}$

${\displaystyle {\begin{alignedat}{2}\Leftrightarrow \mathrm {1\ sb} &=10^{4}\ \pi \ \mathrm {asb} \\&=10^{4}\ \pi \ \mathrm {blondel} \\&=10^{7}\ \pi \ \mathrm {sk} \\&=\pi \cdot \underbrace {\left(\mathrm {{\frac {1}{\pi }}{\frac {cd}{cm^{2}}}} \right)} _{\mathrm {la} }\\&=\pi \cdot \left(\mathrm {\frac {ft}{cm}} \right)^{2}\cdot \underbrace {\left(\mathrm {{\frac {1}{\pi }}{\frac {cd}{ft^{2}}}} \right)} _{\mathrm {ft\ la} }&&\approx 2918{,}6\ \mathrm {ft\ la} \end{alignedat}}}$

With

• ${\displaystyle \mathrm {sk} }$for the scot
• ${\displaystyle \mathrm {la} }$for the Lambert
• ${\displaystyle \mathrm {ft} }$for the foot
• ${\displaystyle \mathrm {ft\ la} }$for the footlambert .

literature

• Arthur N. Cox: Allen's Astrophysical Quantities . Springer, 2000, ISBN 978-0-387-98746-0 ( full text in the Google book search).

Individual evidence

1. ↑ Measure for measure: the story of imperial, metric, and other units in the Google book search