The Metrological Characterization of a Goniometer for the Analysis of Surface Properties

An accurate goniometer was constructed being a part of a system devoted to the measurement of reflecting properties of surfaces. By it a surface of the sample under test can be arbitrarily oriented with respect to the observing direction and the direction of the shooting light beam. The high performances (revolution angle uncertainty equal to 0.1deg) required as specifications for the construction are checked. Particular attention is used to analyze the orthogonality among the revolution axes of each goniometer components and their convergence in the goniometer center. The linearity error of each revolution motion is measured by using a differential method. It proves to be effective to highlight the small linearity deviation and to verify the uncertainty declared by the manufacturer