Integrating-Sphere Photometer

integrating-sphere photometer

[′int·ə‚grād·iŋ ‚sfir fə′täm·əd·ər]
An instrument for measuring the total luminous flux of a lamp or luminaire; the source is placed inside a sphere whose inside surface has a diffusely reflecting white finish, and the light reflected from this surface onto a window is measured by an ordinary photometer. Also known as sphere photometer.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Photometer, Integrating-Sphere


a device that makes it possible to measure luminous flux with a single measurement. The primary assembly of an integrating-sphere photometer is an Uhlbricht sphere—a hollow sphere (or hollow body of a different shape) with the internal surface painted matte white. The diameter of the sphere must significantly exceed the dimensions of the light sources being measured. For example, integrating-sphere photometers up to 5 m in diameter are designed to measure the luminous fluxes of luminescent lamps. The illuminance of any point of the sphere that is shielded by a small screen from the direct rays of a light source within the sphere is proportional to the luminous flux of the source (or in the general case, to the radiation flux). The illuminance of the shielded area may be measured by any of several methods, for example, by means of a photoelectric device built into the sphere. Integrating-sphere photometers are used extensively in light and color measurements, particularly for measuring the luminous fluxes of lamps and luminaires, reflection coefficients, and transmission factors.


Tikhodeev, P. M. Svetovye izmereniia v svetotekhnike: Fotometriia, 2nd ed. Moscow-Leningrad, 1962.
The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.
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