Characterization of window materials using out-of-plane BSDF measurements, combining resolution of small-angle scattering and low level background scattering

Le résumé fourni par la source

The Bidirectional-Scatter-Distribution-Function (BSDF) is well established in research and engineering to describe scattering in terms of radiometry and geometrical optics. Two extreme cases of the BSDF are applicable to windows: First, the near Dirac-delta BSDF of transparent materials, whose imperfections govern the visual clarity. This requires high angular resolution of small-angle scattering and mandates a very ’sharply’ localised light-source. Secondly, measurements of low background scattering of transparent materials, commonly associated with haze, requires a maximum of incident power, with reduced requirements on angular resolution. We present results using our PG2 scanning gonio-photometer that uses the same servo-driven out-of-plane mechanics with different light-sources and sensor opening angles to measure these two extremes of the BSDF and combine them into a common data-set. Aspects of combing high-power incoherent sources with low-power/high-radiance coherent sources are discussed, as well as the influence of optical elements in the source beam-path.

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