Because of the size and shape of these lamps, the luminous flux is more difficult to measure than spherical lamps.
Four types of tubular lamps with lengths ranging from 60 cm to 1.50 m are circulated together with incandescent lamps which serve as reference.
Excellent agreement (about 1%) was obtained by the two laboratories which use the goniophotometer for the measurement of the luminous flux.
Even though the results of some laboratories appeared to be affected by systematic errors related to spectral distribution, length of the tube and distortions in the power supply, they were consistent with the stated uncertainties, and in no case differed by more than 5%. The results of the intercomparison should lead to the revision of the instrumentation and the procedures used in order to reduce disagreement. The intercomparison has, on the whole, managed to provide traceability to the photometric standards maintained at BIPM, IEN, NPL and PTB.
Funding SchemeCSC - Cost-sharing contracts
TW11 0LW Teddington
W1R 9A London