Optical analysis of orange peel on metallic surfaces

Abstract

In this contribution, the orange peel on highly polished metallic surfaces was analysed by means of a 3D interferometric microscope and also using spectroscopic ellipsometry. Firstly, the surface topography of polished metallic samples, in view to detect orange peel, was determined using a phase-shifting interferometer. This metrological 3D analysis showed that the orange peel can be seen as a periodic waviness on the surface. Then the optical properties of the investigated samples were studied via spectroscopic ellipsometry at various incident angles. These ellipsometric measurements proved that the samples have peculiar optical properties. In particular, it was found that the resulting pseudo-dielectric function in the entire range from 1.5 eV to 2.5 eV - as obtained based on the measured ellipsometric parameters - does depend on the surface topography of the samples. Based in this experimental finding, it is then immediately shown that spectroscopic ellipsometry can be applied to qualitatively describe the orange peel on highly polished metallic surfaces.