The goniospectrophotometer GEFE, designed and developed at IO–CSIC (Instituto de Optica, Agencia Estatal Consejo Superior de Investigaciones Cientificas), was conceived to measure the spectral Bidirectional Reflectance Distribution Function (BRDF) at any pair of irradiation and detection directions. Although the potential of this instrument has largely been proved, it still required to be upgraded to deal with some important scattering features for the assessment of the appearance. Since it was not provided with a detector with spatial resolution, it simply could not measure spectrophotometric quantities to characterize texture through the Bidirectional Texture Function (BTF) or translucency through the more complex Bidirectional Scattering–Surface Reflectance Distribution Function (BSSRDF). Another requirement in the GEFE upgrading was to provide it with the capability of measuring fluorescence at different geometries, since some of the new pigments used in industry are fluorescent, which can have a non–negligible impact in the color of the product. Then, spectral resolution at irradiation and detection had to be available in GEFE. This paper describes the upgrading of the goniospectrophotometer GEFE, and its new capabilities through the presentation of sparkle and goniofluorescence measurements. In addition, the potential of the instrument to evaluate translucency by the measurement of the BSSRDF is briefly discussed.

Date Published: 13 March 2015
PDF: 11 pages
Proc. SPIE 9398, Measuring, Modeling, and Reproducing Material Appearance 2015, 93980E (13 March 2015); doi: 10.1117/12.2077084

Published in SPIE Proceedings Vol. 9398:
Measuring, Modeling, and Reproducing Material Appearance 2015
Maria V. Ortiz Segovia; Philipp Urban; Francisco H. Imai, Editor(s)