Sensitivity calculations are given for a novel ellipsometric technique that involves a rotating polarizer or analyzer and the measurement of signal phase angles. It is superior to optical null techniques under signal-limited conditions, and avoids the difficulties that attend precise signal-amplitude measurements. Noise coefficients as functions of optical-component settings and surface properties are presented for the technique and compared with those for the conventional ellipsometer.
R. W. Stobie, B. Rao, and M. J. Dignam, "Analysis of a novel ellipsometric technique with special advantages for infrared spectroscopy," J. Opt. Soc. Am. 65, 25-28 (1975)