Geometry influence on the precision of light flux measurement with ulbricht integrating sphere

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Abstract
Integrating sphere is a device that canhave important structural dimensions and weight, generating the possibility for somedeformations to occur. In general, the measurement chains are used with the analysis of the sources of errors, but no information was found about the errors generated by the integrating sphere itself. Geometric errors caused by imperfections could generate systematic errors, even immediately after sphere calibration with a standard source of light. The phenomenon of multiple reflections on a surface which is not spherical will induce errors that depend on the lighting distribution of the measured luminaire and his mounting position. The paper examines these assumptions to estimate the scale of the geometric imperfections (constructive or created in time) in correlation with the errors introduced in the measured luminous flux. Original MAT LAB functions and DIALux are used to evaluate the light reflection between surfaces.