Calculation of the combined uncertainty in a rotating mirror goniophotometer of type C and an integrating sphere

Abstract

This work presents evaluation of combined uncertainty in an Ulbricht Sphere and a Rotating mirror Goniophotometer C-Type. It was considered the standards of norm ISO17025:2005, where it shows the components of the combined uncertainty calculus for Test Laboratory Accreditation. The values were obtained from a theoretical mathematical model for Luminous Flux and Luminous Intensity. In the Ulbricht Sphere the model depends of the test lamp, due to their electrical components properties. There are two models: one for the incandescent lamps and another for discharge lamps. It was used, as a reference lamps, one standard lamp of luminous flux and one standard lamp of luminous intensity, both traceable to the International Committee for Weights and Measures (Comité international des poids et mesures CIPM). It were included the factors that contribute to the uncertainty as temperature, self-absorption, stray light, and it were quantified for the numerical calculus. Finally, the expanded uncertainty (k=2) of Integrating Sphere for an incandescent test lamp was 2.52%, for an discharge test lamp was 3.21% and the goniophotometer uncertainty was 2.14%.