In this paper, the design of an inexpensive integrating sphere setup is presented, enabling students
to perform optical characterization of light sources with reasonable accuracy, in a student
laboratory context. Instead of using an expensive sphere with magnesium oxide or barium sulfate
coating, a cheap polystyrene sphere is employed. In combination with a low-cost USB
spectroradiometer, the system enables the direct measurement of the spectral radiant power of a
light source. In addition to the radiant power, the luminous flux, luminous efficacy, and
distinctive colorimetric quantities (colour coordinates, colour temperature, and colour rendering
index) can be determined. Besides a description of the equipment used, the experimental measurement
procedure and some typical measurement results are presented. A comparison between the data and the
results obtained with scientific metrology instrumentation indicates reasonable accuracy. As a
result, it can be concluded that the purp…