Trilateral Intercomparison of Photometric Units Maintained at NIST (USA), NPL (UK), and PTB (Germany) |
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Authors: | Yoshi Ohno Teresa Goodman Georg Sauter |
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Affiliation: | National Institute of Standards and Technology, Gaithersburg, MD 20899-8442 USA;National Physical Laboratory, Queens Road, Teddington, Middlesex TW11 0LW UK;Physikalisch-Technische Bundesanstalt, Abteilung Optik, Photometrie, Postfach 33 45, 38023 Braunschweig, Germany |
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Abstract: | A trilateral intercomparison of photometric units between NIST (USA), NPL (UK), and PTB (Germany) has been conducted to update the knowledge of the relationship between the photometric units disseminated in the three countries. The luminous intensity unit (cd), the luminous responsivity scale (A/lx), and the luminous flux unit (lm) maintained at each laboratory were compared by circulating transfer standard lamps and photometers. The results showed that the relative luminous intensity values, with respect to the average, measured by NIST, NPL, and PTB were 1.0014, 1.0021, and 0.9966; the relative inverse values of the luminous responsivity (corresponding to illuminance) were 1.0023, 1.0011, and 0.9965; the relative luminous flux values were 0.9994, 1.0034, and 0.9972, respectively. The results agreed within the stated uncertainties of the units maintained at the three laboratories. |
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Keywords: | illuminance intercomparison luminous flux luminous intensity luminous responsivity photometer photometry units |
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