Rapid growth of the market of LEDs for lighting gives us urgent needs for establishment of product certification system. Having accurate and recognized measurements followed by international standardization are indispensable to ensure the reliability of the LED products with the product certification system. In this article, some technical issues about the photometry and radiometry of LEDs and recent topic and trend of the international standardization are reviewed.

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Recently, Uncertainty is becoming one of the important criteria for showing the capability of a test laboratory in LED photometric and radiometric field. This report describes the Uncertainty evaluation methods for total luminous flux measurements with goniophotometry. The mathematical model is construced based on the measurement procedure to look for the Uncertainty factors. And the evaluation methods are explained about the typical factors in the budget.

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We tried to verify the precision of the measurement of total luminous flux as mirror-type Goniophotometer at Japan Electrical safety & environment Technology laboratories (JET), this study provides for effects of ambient temperature, dead angle and stray light in total luminous flux measurement using the mirror-type Goniophotometer.

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Intercomparison of the measured total-luminous-flux values among the sphere photometers using the 76-inch, 40-inch integrating spheres and 40-inch hemisphere, and the 3.3 foot photometric distance goniophotometer was performed, and then their consistency was considered. Although stably-lighting LED lamps were selected after 100-hour aging, about 1 hour aging was required to have them stable before the measurement. Reproducibility including the difference in equipments was less than ±0.2 %. The total-luminous-flux of omnidirectional lamps having the angular luminous intensity distribution same as a standard lamp accorded in less than ±0.6 % among the sphere photometers and the goniophotometer. On the other hand, the total-luminous-flux of directional lamps accorded in more than ±1.5 %. It is thought that the total-luminous-flux of directional lamps is attenuated because of the influence of the lamp support stand and other structures in the 40-inch integrating sphere. Since the measured value of the integration hemisphere is the same as those of the large integrating spheres, there is little error caused by the structures in it.

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