photometer

Estimated CEFR level: C2 — Proficiency

Estimated from word frequency; not an official CEFR classification.

Definition

noun measuring instrument for measuring the luminous intensity of a source by comparing it (visually or photoelectrically) with a standard source
noun photographic equipment that measures the intensity of light

From photo- + -meter.

They can see the changes in intensity faster than I can plot them on the photometer!" — The Colors of Space, Marion Zimmer Bradley
For the physicist speaks of degrees of luminous intensity as of real quantities: and, in fact, he measures them by the photometer. — Time and Free Will: An Essay on the Immediate Data of Consciousness, Henri Bergson

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