Apostilb

Apostilb ( unit symbol asb ) is an outdated unit of luminance of self-luminous bodies. In 1942, Blondel (unit symbol: blondel ) was proposed as a further name, the name was chosen in memory of the French physicist André-Eugène Blondel . A use or official definition of this name is currently not verifiable. Since 1978 the apostilb is no longer an official unit . It is a sub-unit of the Stilb (unit symbol:) and above it linked to the Lambert (unit symbol:) : ${\displaystyle \mathrm {sb} }$ ${\displaystyle \mathrm {la} }$

${\displaystyle 1\,\mathrm {asb} =1\,\mathrm {blondel} ={\frac {1}{\pi }}\cdot 10^{-4}\ \mathrm {sb} =10^{-4}\ \mathrm {la} }$

The corresponding SI unit is cd / m² (non-SI-compliant alternative designation: Nit (nt) ):

${\displaystyle {\begin{aligned}1\,\mathrm {asb} &={\frac {1}{\pi }}\cdot {\frac {\mathrm {cd} }{\mathrm {m^{2}} }}={\frac {1}{\pi }}\,\mathrm {nt} \\\Leftrightarrow \pi \,\mathrm {asb} &=1\cdot {\frac {\mathrm {cd} }{\mathrm {m^{2}} }}\end{aligned}}}$

Web link

• Luminance Unit Measurement Converter

Individual evidence

1. ↑ sizes.com: blondel , according to: Journal of the Optical Society of America, volume 32, pages 348-362.
2. ↑ Peter Kurzweil, Bernhard Frenzel, Florian Gebhard: Physics formula collection for engineers and scientists . Vieweg, Wiesbaden 2008, ISBN 978-3-8348-0251-4 , pp. 4 .