photometer

[foh-tom-i-ter]
noun Optics.
an instrument that measures luminous intensity or brightness, luminous flux, light distribution, color, etc., usually by comparing the light emitted by two sources, one source having certain specified standard characteristics.

Origin:
1770–80; < Neo-Latin photometrum. See photo-, -meter

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World English Dictionary
photometer (fəʊˈtɒmɪtə)
 
n
See also spectrophotometer an instrument used in photometry, usually one that compares the illumination produced by a particular light source with that produced by a standard source

Collins English Dictionary - Complete & Unabridged 10th Edition
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Encyclopedia Britannica
Encyclopedia

photometer

device that measures the strength of electromagnetic radiation in the range from ultraviolet to infrared and including the visible spectrum. Such devices are generally transducers that convert an electric current into a mechanical indication-e.g., a pointer moving across a dial. The source of the current may be a selenium cell, which generates a current when light falls on it, or it may be a permanent source, such as a battery, in which case the current passes through a cadmium sulfide cell whose resistance varies with the amount of light falling on it.

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Encyclopedia Britannica, 2008. Encyclopedia Britannica Online.
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Example sentences
Color intensity is quantified using a portable photometer.
If the photometer is not calibrated in candlepower, record the unit of measurement and calculate candlepower.
Schematic of a setup for using an absolutely calibrated photometer to perform luminous intensity and illuminance measurements.
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