Precision Bounds to Ellipsometer Systems

The theoretical precision attainable from a number of types of ideal null and photometric ellipsometers is investigated quantitatively. Photometric and modulated null ellipsometer systems are shown to be approximately comparable with respect to precision when operating under shot-noise limited conditions. Differences are due principally to intrinsic detector noise levels, which are more significant in null designs. The equations derive can be used to estimate practical measurement limits or to choose components to achieve a specific objective.