Polarization artefacts correction procedure for a spectro-polarimetric goniometer

A new goniometric device for spectro-polarimetric BRDF measurements is under development. This goniometer will measure linear and circular polarization of materials. Different instrument quality tests were realized in order to identify factors affecting the measured spectra and to obtain functional relationship between the instrument output and the real reflective properties of the materials. The most limiting of all factors influencing measured spectra was the polarization sensitivity of the spectrometer. Moreover, optical fiber bundle connected to the spectrometer input has unpredictable behavior in polarized light. In this paper, we present the artefacts produced by sensitivity of the spectrometer to the polarized light and describe the adequate measurement procedure to maintain instrument response under control and to acquire reliable BRDF measurements.