The energy efficiency of lighting products is described in terms of luminous efficacy. It is the ratio of the produced total luminous flux and the consumed active electrical power. Luminous flux, the total amount of visible light produced by a light source, as perceived by the human eye, is often measured with integrating sphere photometers. Low uncertainties in measurements with integrating spheres require a correction factor to account for the spatial non-uniformity of the sphere. Traditionally, obtaining this correction factor has required time consuming and resource intensive goniometric measurements of the relative angular intensity distribution of the lamp under test.In this thesis, a fisheye camera method for determining spatial non-uniformity corrections in luminous flux measurements with integrating spheres is presented. Using a fisheye lens camera mounted into the detector port of an integrating sphere, the relative angular intensity distribution of a luminaire operated inside the sphere is resolved. The developed method does not require any modifications to the integrating sphere. To automate the measurement procedure, measurement and analysis software utilizing the method was developed.The developed method and software were validated by measuring the relative angular intensity distributions of twelve LED lamps of different types using the fisheye camera method with two different grade camera modules and a goniophotometer for the reference. For the luminaires tested, the deviations between the spatial correction factors obtained using the two methods ranged from 0.01 % to 0.32 %, depending on the angular spread of the measured lamp. For the fisheye camera method and a typical LED lamp, the expanded uncertainty (k = 2) for the spatial non-uniformity correction factor was determined to be 0.28 %.
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