Interpretation of integrating sphere signal output for non-Lambertian samples.
A new formalism is derived for the analysis of signal output from double-beam integrating spheres. The analysis explicitly considers the effects of port losses and a non-Lambertian sample surface and introduces a separation of the diffusely reflected light into two parts: one which should be analyzed as a specular component and one which is fully diffuse. An experimental procedure to determine the two parameters in the formalism is described for two cases, a brushed copper and a rolled aluminum surface, and it is experimentally verified that the formalism eliminates spurious structure from the barium sulfate reference. A criterion is also given for the selection of barium sulfate or polytetrafluorethylene powder as a reference material.
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Roos
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Ribbing