Characterization of the gonioapparent character of colored anodized titanium surfaces

We investigate the gonioapparent character of colored anodized titanium surfaces. In appropriate experimental conditions, the anodizing process generates a homogeneous oxide layer at the surface of the metal, with a thickness comparable with the visible wavelengths of light. The anodized metallic surfaces thus exhibit interferential colors, which depend on the thickness of the oxide layer and have the particularity to vary according to the illumination and observation directions. They are said to be gonioapparent. This article describes an experimental method to characterize these variations precisely. (c) 2014 Wiley Periodicals, Inc. Col Res Appl, 40, 483-490, 2015