NEW ULTRA-FAST INTERFEROMETRIC ELLIPSOMETRY SYSTEMS BASED ON A ZEEMAN 2-FREQUENCY LASER

It is shown that it is possible to improve the Hazebroek-Holscher interferometric ellipsometer by using a two-frequency Zeeman laser. Several optical configurations are described and theoretically analysed. The most convenient one is what we call the Le Poole system. It yields the ellipsometric angles Delta and Psi as in the Hazebroek-Holscher set-up. The new system retains the advantages of the Hazebroek-Holscher set-up, but avoids the use of any moving or rotating components and increases the signal frequency to a few megahertz (the frequency difference of the two Zeeman laser beams). So the Zeeman ellipsometer offers a new measurement technique for the study of very fast (surface) processes.