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luminous intensity

Luminous flux emitted by a source in a given range of directions; the unit of measure is the lumen/steradian, now known as the candela.

mean spherical luminous intensity

The average luminous intensity of a point light source measured over all directions.

candela

SI unit of luminous intensity. It is defined as one sixtieth the normal intensity of one square centimeter of a blackbody at the solidification temperature of platinum. A point source of one candela...

candlepower

The luminous intensity of a source of light expressed in candelas.

comparison lamp

A reference incandescent light source having a luminous intensity that is used in photometry for comparison of other light sources.

Hefner unit lamp

A gas lamp used in the early 1900s as a physical standard for measurement of luminous intensity. The Hefner unit was superseded by the candle and then by the candela.

international candle

A unit of measurement of luminous intensity based on a physical standard, a set of calibrated carbon filament lamps. The old candle unit was superseded by the new candle or candela.

lumen

A lumen is a unit of measurement used to quantify the amount of luminous flux, which is the perceived power of light. In other words, the lumen measures the total amount of visible light emitted by a...

mcd

millicandela — The millicandela is equivalent to one thousandth (or 10-3) of the standard unit of luminous intensity that is the candela, which is the power emitted by a given light source in a particular direction.

Waidner-Burgess standard

A standard of luminous intensity evaluated as the luminous intensity of 1 cm2 of a blackbody at the melting point of platinum.

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