Disclosed are spectroscopic ellipsometer and combined spectroscopic reflectometer/ellipsometer systems. The spectroscopic ellipsometer system portion includes polarizer and analyzer elements which remain fixed in position during data acquisition, and a step-wise rotatable compensator electromagnetic beam transmitting means, which serves to enable imposing a plurality of sequentially discrete, rather than continuously varying, polarization states on said beam of electromagnetic radiation. Further disclosed is a calibration procedure for said spectroscopic ellipsometer system portion of the invention which involves the gathering of, for each of a plurality of ellipsometrically distinct sample systems, spectroscopic data at a sequential plurality of discrete electromagnetic radiation beam polarization states, combined with providing of a mathematical model of the spectroscopic ellipsometer system and application of a mathematical regression procedure.