The apostilb is an obsolete unit of
luminance
Luminance is a photometric measure of the luminous intensity per unit area of light travelling in a given direction. It describes the amount of light that passes through, is emitted from, or is reflected from a particular area, and falls withi ...
.
The
SI unit of luminance is the
candela per square metre
The candela per square metre (symbol: cd/m2) is the unit of luminance in the International System of Units (SI). The unit is based on the candela, the SI unit of luminous intensity, and the square metre, the SI unit of area. The nit (symbol: n ...
(cd/m
2). In 1942 Parry Moon proposed to rename the apostilb the blondel, after the French physicist
André Blondel
André-Eugène Blondel (28 August 1863 – 15 November 1938) was a French engineer and physicist. He is the inventor of the electromechanical oscillograph and a system of photometric units of measurement.
Life
Blondel was born in Chaumont, Ha ...
.
The symbol for the apostilb is asb.
The apostilb is defined in terms of another unit of luminance, the
stilb (sb):
:1 asb = 1/ ⋅ 10
−4 sb
: asb = 1 cd/m
2
See also
Other units of luminance:
*
Lambert (L)
*
Skot (sk)
*
Bril (bril)
*
Nit (nit)
*
Foot-lambert
A foot-lambert or footlambert (fL, sometimes fl or ft-L) is a unit of luminance in United States customary units and some other unit systems. A foot-lambert equals 1/π or 0.3183 candela per square foot, or 3.426 candela per square meter (the corre ...
(fL)
References
{{reflist
Units of luminance
Centimetre–gram–second system of units