Appearance Measurements Of Goniochromatic Colours

Abstract

Effect pigments with their angular dependent colour impression entering more and more the portfolio of commercial products. Caused by the goniochromatic behaviour of the appearance of such objects, the spectral reflection properties in three- dimensional space must be determined in order to describe these objects appropriately. For this purpose a gonioreflectometer is needed with the ability to perform measurements of the spectral radiance factor respectively the BRDF within the full half-space (2π sr) above the device under test. At the Physikalisch-Technische Bundesanstalt (PTB), the National Metrology Institute (NMI) of Germany, such a facility for measuring appearance-related quantities has been built up. The system is named ARGon3 which stands for "3D Appearance Robot-based Gonioreflectometer". The main features within the set-up are a photometric luminance camera with a spatial resolution of 28 µm on the device under test and a line-scan camera mounted to a spectrograph, which provides measurements of spectral resolved reflection in full V(λ)-range with arbitrary angles of irradiation and detection relative to the surface normal. Within this publication goniometric measurements of reflection within 3D-space and subsequent colorimetric representation of the obtained data of a special effect pigment called Viola Fantasy from MERCK KGaA, Darmstadt, Germany are presented. This record was migrated from the OpenDepot repository service in June, 2017 before shutting down.