It is the Multiskop, by Optrel GmbH, it works in extinction mode at single wavelength (632.8 nm).
Operational modes include:
Here you find an tutotial on the basics of the ellipsotric technique.
You can also find a detailed description in [H.Harke, R. Teppner, O.Schulz, H.Orendi, H. Motschmann, Rev.Sci.Instrum. 68(8) August 1997]