Metrological traceability for (O)LEDs
German article by Dr. Tobias Schneider
The SI units are disseminated by calibrations based on a chain of measurements. If this chain can be unequivocally traced to a primary representation of the SI units, this is referred to as the “(metrological) traceability” of a measurement. The measurement uncertainties that occur in every measurement are of crucial importance for metrological traceability (see info box Measurement Uncertainty). They form the links in the “chain” and establish a demonstrable link to the primary representations of the SI units and constitute a quantitative description of the uncertainty of a measurement at each point of the chain. Measurement uncertainties in the chain thus determine how long and flexible the calibration chain is to any point. A complex network of organizations, contracts and standards ensure internationally consistent implementation of metrological traceability to the SI unit system and thereby enable a practically useable realization of the SI system (Figure 1).