Proposal for ellipsometer configurations allowing phase-sensitive detection

We propose ellipsometer configurations where, by conveniently modulating either the input or the output polarization, one can determine the ellipsometric parameters, D and psi, purely from phase measurements on two harmonic components of the signal from a single detector. Such phase measurements are less sensitive to noise than the conventional amplitude measurements, and the proposed modulation techniques can allow the achievement of frequencies up to tens of megahertz. Thus a very good time resolution is achieved.