2.2 - Optical twist measurement by scatterometry

A. Hertzsch, K. Kröger & M. Großmann
To ensure that seals do not leak one of the main requirements for the shaft surface is the absence of twist structures. Twist is a periodic, generally thread-shaped microstructure which is superimposed on the roughness of the shaft surface and takes the form of waviness in the axial and circumferential directions. Using an optimized scattering geometry light scattering leads to an intensified mapping of the periodic twist structure of the shaft surface. The optical filtering...