Analysis of the Performance of a Goniometer for Studying Surface Reflection

An accurate goniometer was constructed, being a part of a system that is designed for the measurement of reflecting properties of surfaces. It can be used to orient a surface of the sample under test arbitrarily with respect to the observing direction and the direction of the shooting light beam. The high performance (revolution angle uncertainty equal to 0.1deg), which is required as a specification for the construction, is checked. Particular attention has been given to analyzing the orthogonality among the revolution axes of each goniometer component and their convergence in the goniometer center. The linearity error of each revolution motion has been measured by using a differential method, which proves to be effective in highlighting the small linearity deviation and verifying the uncertainty declared by the manufacturer.