photn.

Brit.

/fəʊt/, U.S.

/foʊt/,

/fɑt/

Inflections: Plural unchanged, phots.

Origin: A borrowing from French. Etymon: French phot.

Etymology: < French phot (1894 in the source translated in quot. 1894 at sense 1; 1903 in sense 2) < ancient Greek ϕωτ- , ϕῶς light (see photo- comb. form).

Physics.

†1. A unit of the product of illumination and duration, equivalent to one lux maintained for one second. Obsolete.

ΘΚΠ

the world > matter > physics > electromagnetic radiation > light > intensity of light, luminosity > [noun] > unit of light intensity > superseded terms

standard candle1850

phot1894

photon1916

1894 tr. A. Blondel in Electrician 28 Sept. 634/2 Some years ago the photographers..established under the presidency of eminent savants (MM. Abney, Cornu, Janssen, Sébert, Violle, &c.), a unit of time-illumination (illumination) specially applicable to photography, the ‘phot’.

2. A unit of illumination equal to 10,000 lux (one lumen per square centimetre).

ΘΚΠ

the world > matter > physics > electromagnetic radiation > light > intensity of light, luminosity > [noun] > unit of light intensity

lux1889

lumen1898

L1915

Lambert1915

phot1917

new candle1938

candela1950

cd1950

rayleigh1956

1917 Trans. Illuminating Engin. Soc. (U.S.) 12 440 Using the centimeter as the unit of length, the unit of illumination is one lumen per square centimeter, for which Blondel has proposed the name ‘phot’. One millilumen per square centimeter (milliphot) is more useful as a practical unit.

1939 A. W. Barton Text Bk. Light ix. 197 A metre-candle is equal to a lumen per square metre,..so that there are 10,000 metre-candles in a phot.

1953 S. W. Amos & D. C. Birkinshaw Television Engin. I. 280 The phot is rather a large unit, and its submultiple the milliphot (equal to 10⁻³ phot) is frequently used.

1972 Electroencephalogr. & Clin. Neurophysiol. 32 309 The measured illumination at the same distance from the hemisphere as the subjects' eyes was 150 phots.

1995 Vision Res. 35 776/2 At the highest mean illuminance our mixed receptoral stimulation was 539 phot td..and 465 phot td for the rod isoluminant stimuli.

This entry has been updated (OED Third Edition, March 2006; most recently modified version published online March 2022).

单词	phot
释义	photn. Brit. /fəʊt/, U.S. /foʊt/, /fɑt/ Inflections: Plural unchanged, phots. Origin: A borrowing from French. Etymon: French phot. Etymology: < French phot (1894 in the source translated in quot. 1894 at sense 1; 1903 in sense 2) < ancient Greek ϕωτ- , ϕῶς light (see photo- comb. form). Physics. †1. A unit of the product of illumination and duration, equivalent to one lux maintained for one second. Obsolete. ΘΚΠ the world > matter > physics > electromagnetic radiation > light > intensity of light, luminosity > [noun] > unit of light intensity > superseded terms standard candle1850 phot1894 photon1916 1894 tr. A. Blondel in Electrician 28 Sept. 634/2 Some years ago the photographers..established under the presidency of eminent savants (MM. Abney, Cornu, Janssen, Sébert, Violle, &c.), a unit of time-illumination (illumination) specially applicable to photography, the ‘phot’. 2. A unit of illumination equal to 10,000 lux (one lumen per square centimetre). ΘΚΠ the world > matter > physics > electromagnetic radiation > light > intensity of light, luminosity > [noun] > unit of light intensity lux1889 lumen1898 L1915 Lambert1915 phot1917 new candle1938 candela1950 cd1950 rayleigh1956 1917 Trans. Illuminating Engin. Soc. (U.S.) 12 440 Using the centimeter as the unit of length, the unit of illumination is one lumen per square centimeter, for which Blondel has proposed the name ‘phot’. One millilumen per square centimeter (milliphot) is more useful as a practical unit. 1939 A. W. Barton Text Bk. Light ix. 197 A metre-candle is equal to a lumen per square metre,..so that there are 10,000 metre-candles in a phot. 1953 S. W. Amos & D. C. Birkinshaw Television Engin. I. 280 The phot is rather a large unit, and its submultiple the milliphot (equal to 10⁻³ phot) is frequently used. 1972 Electroencephalogr. & Clin. Neurophysiol. 32 309 The measured illumination at the same distance from the hemisphere as the subjects' eyes was 150 phots. 1995 Vision Res. 35 776/2 At the highest mean illuminance our mixed receptoral stimulation was 539 phot td..and 465 phot td for the rod isoluminant stimuli. This entry has been updated (OED Third Edition, March 2006; most recently modified version published online March 2022). < n.1894
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