View source for Top-hat filter

The '''stilb''' ('''sb''') is the [[CGS]] unit of [[luminance]] for objects that are not self-luminous. It is equal to one [[candela]] per square centimeter or 10<sup>4</sup> [[Nit (unit)|nits]] (candelas per square meter). The name was coined by the French physicist [[André Blondel]] around 1920.<ref>Parry Moon. "System of photometer concepts", in the ''Journal of the Optical Society of America'', volume 32, number 6 (June 1942). – Page 355: "The lumen was proposed by Blondel in 1894 and is now universally accepted. The names, phot and stilb were likewise coined by Blondel (1921) and are in general use on the Continent."</ref> It comes from the Greek word ''stilbein'' meaning "to glitter".

It was in common use in Europe up to [[World War I]]. In North America self-explanatory terms such as candle per square inch and candle per square meter were more common.<ref>''American Standard Definitions of Electrical Terms'', New York: American Institute of Electrical Engineers, 1941.</ref> The unit has since largely been replaced by the SI unit: [[candela per square meter]]. The current national standard for SI in the United States discourages the use of the stilb.<ref>IEEE/ASTM SI 10-2002. ''American National Standard for Use of the International System of Units (SI): The Modern Metric System''. New York: IEEE, 30 December 2002. See Section 3.3.3.</ref>

==Unit conversion==
<!-- 1. conversion of stilb into SI-units --><math>\mathrm{1\, \frac{cd}{m^2} = 10^{-4}\, sb}</math>
<br/><br/>
<!-- 2. conversion of other CGS and SI units into stilb --><math>\mathrm{1\, sb = 1\,\frac{cd}{cm^2} = 10^4\,\frac{cd}{m^2}}</math>
<br/><br/>
<!-- 3. conversion of other coherent units into stilb --><math>\mathrm{1 \, sb = 10^4 \, nit = 10^7 \, millinit}</math>
<br/><br/>
<!-- 4. conversion of non-coherent units into stilb, for which an exact representation is possible --><math>\mathrm{1 \, sb = 1 \pi \, L = 10^3 \pi \, mL = 10^4 \, \pi \, asb = 10^4 \pi \, blondel = 10^7 \pi \, sk = 10^{11} \pi \, bril}</math>
<br/><br/>
<!-- 5. conversion of non-coherent units into stilb, for which no exact representation is possible --><math>\mathrm{1 \, sb = 10^4\,\frac{cd}{m^2} \approx 0.3048^2 \cdot 10^4 \cdot \pi \,\, fL = 2918.6...\, fL}</math>

==See also==

Other units of luminance:
<!-- in order of relevance in regard to stilb -->
* [[Nit (unit)|Nit]]&nbsp;(nit and millinit)
* [[Apostilb]]&nbsp;(asb)
* [[Blondel (unit)|Blondel]]&nbsp;(blondel)
* [[Skot (unit)|Skot]]&nbsp;(sk)
* [[Bril (unit)|Bril]]&nbsp;(bril)
* [[Lambert (unit)|Lambert]]&nbsp;(L and mL aka millilambert)
* [[Foot-lambert|Footlambert]]&nbsp;(fL)

{{SI light units}}

==Notes and references==
* [http://www.unc.edu/~rowlett/units/dictS.html Stilb ] at ''A Dictionary of Units of Measurement'', Russ Rowlett and the University of North Carolina at Chapel Hill. Accessed June 2008.
* [http://www.sizes.com/units/stilb.htm Stilb] at Sizes.com. Accessed June 2008.
<references/>

[[Category:Photometry]]
[[Category:Units of luminance]]
[[Category:Centimetre–gram–second system of units]]

{{physics-stub}}