☙
A unit of luminance suggested in 1942, and named for the French physicist Andrè-Eugène Blondel (1863-1938). One blondel is pi lumens per square meter per steradian; it is equivalent to the apostilb.
Parry Moon.
A system of photometric concepts.
Journal of the Optical Society of America, volume 32, pages 348-362 (June 1942).
Page 356: “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 Andrè Blondel who did pioneer work in photometric nomenclature.”
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Last revised: 20 January 2009.