A Spectroscopic Rotating Compensator Material System Investigation System including a Dual Waveplate Pseudo-Achromatic Compensator System, and a Photo-Array for simultaneously detecting a Multiplicity of Wavelengths, is disclosed. The Spectroscopic Rotating Compensator Material System Investigation System is calibrated by a Mathematical Regression based technique involving, where desirable, Parameterization of Calibration Parameters. Calibration is possible utilizing various dimensional Data Set(s) obtained with the Spectroscopic Rotating Compensator Material System Investigation System in a 'Material System present' or in a Straight-through' configuration, said data sets being variously normalized to D.C., A.C. or combination D.C. and A.C. components thereof.
Regression calibrated spectroscopic rotating compensator ellipsometer system with pseudo-achromatic retarder system