Ellipsometry is a widely used method for characterizing materials and thin films. The advantages of ellipsometry are nondestructive measurement and high precision. This method can be applied to many different applications, for example, semiconductor, chemistry, and display industry. Ellipsometers measure polarization changes at a sample in reflection or transmission configurations. Measurements in these arrangements are only possible for plane or near plane surfaces. Even slight misalignments from the ideal setting might lead to significant experimental errors. For larger misalignments, it is mostly even not possible to get any evaluable signals. To overcome this restriction, the concept of retroreflective ellipsometry was developed. The combination of reflectometric and ellipsometric measurement of samples can provide optical properties and surface topometry of samples. The retroreflector in this setup has high tilt angle tolerance, i.e., inline measurement is possible.