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Sunlight in atmosphere is a major cause of damage to paints, plastics, inks and other polymers, which causes billions of dollars in economic losses each year. Therefore, for many products, anti-aging ability and light stability are very important. The paper introduces two kinds of fluorescent UV lamps and xenon arc lamps which are most widely used as light sources in chambers. According to JJF1525-2015 Calibration Specification for Irradiance of Artificial Accelerated Weathering Apparatus of Xenon Arc Lamp, there are three methods to detect the irradiance: radiometer method, spectroradiometer method and standard lamp method. By analyzing the advantages and disadvantages of different measurement methods, we suggest to adopt the radiometer method in daily calibration. By radiometer method, the irradiance of two lamps both are usually calibrated at the wavelength of 340nm. In daily calibration, we found that the data of same radiometer is obviously different when we calibrating two aging chambers with different light sources. By comparisons, the main reason of the difference is different light source spectrums. The difference of spectral irradiance between lamps introduces errors in calibration. This paper provides practical experience and technical guidance for daily calibration.
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