Apostilb Explained

The apostilb is an obsolete unit of luminance.^[1] The SI unit of luminance is the candela per square metre (cd/m²). In 1942 Parry Moon proposed to rename the apostilb the blondel, after the French physicist André Blondel.^[2] 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/m²

See also

Other units of luminance:

• Lambert (L)
• Skot (sk)
• Bril (bril)
• Nit (nit)
• Foot-lambert (fL)

Notes and References

1. Web site: IPS Perimetric Standards, 1978 . Imaging and Perimetry Society . 1978.
2. Parry . Moon . A system of photometric concepts . Journal of the Optical Society of America . 32 . 6 . 356 . June 1942 . 10.1364/JOSA.32.000348 . The unit is pi times the lumens per square meter per steradian. Such a name is impossibly cumbersome, so a new name is proposed, the blondel, after André Blondel who did pioneer work in photometric nomenclature.. 1942JOSA...32..348M .