Abstract

Although often colorful and of historical interest, some radiometric and photometric units are redundant and illogical. The essential units are few in number. These, together with their definitions and conversion factors, are presented here.

© 1968 Optical Society of America

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Figures (1)

Fig. 1
Fig. 1

CIE spectral luminous efficiency curve, showing sensitivity of the human eye to different wavelengths of radiant energy.

Tables (3)

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Table I Radiometric and Photometric Symbols and Units

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Table II Conversion Factors for Units of Luminance

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Table III Conversion Factors for Units of Illuminance

Equations (8)

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w = Q / V .
ϕ = Q / t .
1 joule 1 second = 1 watt , W = J s - 1 .
I = ϕ / ω .
d ω = d A cos θ / D 2 ,
M = ϕ / A .
L = ( 2 ϕ ) / ( A ω cos θ ) = I / ( A cos θ ) .
E = ϕ / A .

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