A study of spectral correction for self‐absorption of radiation unit in integrating sphere spectral photometer

Abstract

AbstractIntegrating sphere spectral photometers are used to measure the spectral distribution, to calculate the total luminous flux, and to calculate the chromaticity coordinates of LEDs. When measuring the light source emission in an integrating sphere it is necessary to take account of self‐absorption. LEDs with colored parts, such as printed circuit boards, heat sinks, etc., require special attention. In case of a large enough sphere, the self‐absorption spectrum of an LED has a nearly flat spectral distribution and a low absorption level. Hence, the calculated total luminous flux and chromaticity coordinates of the LED are almost the same regardless of whether the self‐absorption correction is applied or not. In the case of a small integrating sphere, the spectral distribution of LED self‐absorption is slightly affected by spectrum correction samples. The correction spectrum can be measured individually for each color piece with an auxiliary lamp set up in the integrating sphere. After spectral correction, the values of the total luminous flux and chromaticity coordinates measured in a small integrating sphere closely match the results obtained in the large sphere. © 2010 Wiley Periodicals, Inc. Electron Comm Jpn, 93(12): 10–16, 2010; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/ecj.10293