ANALYSIS OF EDGE-LOSSES IN REFLECTANCE MEASUREMENTS OF PIGMENTED MAXILLOFACIAL ELASTOMER

Edge-losses occur during reflectance measurements of pigmented maxillo facial elastomer when light is scattered within a sample beyond that p art of the surface exposed to the observation system of the optical de vice. A custom sample-holder is presented which redirects light that w ould not be measured during conventional reflectance measurement back into the sample. The amount of edge-loss occurring within thin layers of maxillofacial elastomer with tan pigment on black-and-white backing s was found to depend on sample thickness, the backing, the beam size used during conventional reflectance measurement, and the optical term bS = (2KS + K-2)(1/2). Data analysis revealed a significant interacti on among these four factors. Additionally, the edge-loss occurring dur ing the tristimulus reflectance measurement of thick samples of maxill ofacial elastomer with various concentrations of tan and black pigment was found to be linearly related to bS up to a limiting value, with n o additional edge-loss occurring for bS values above this limiting val ue. Edge-loss is an important consideration during the matching of the optical characteristics of pigmented maxillofacial material to those of human skin.