Electrical & Computer Engineering, Department of


Date of this Version



United States Patent Number: 5,757,494. Date of Patent: May 26, 1998.


The present invention is applicable generally to Spectroscopic Rotatable and Rotating Element Ellipsometers which utilize a relatively large range of wavelengths. Disclosed is a system and method for controlling the polarization state of a polarized beam of light so that it is in a range where the sensitivity of a Polarization State Detector used to measure changes in said polarized beam of light resulting from interaction with a Sample System. to noise and measurement errors etc.. is reduced. Exemplified is a system. and method of use, for simultaneously setting both measured ellipsometric ALPHA, and ellipsometric BETA parameter values, (or equivalents), within ranges. in which ranges the sensitivity of transfer functions. and mathematical regressions which utilize said ellipsometric ALPHA and ellipsometric BETA values in the calculation of sample system characterizing PSI and DELTA constant values. to noise and errors in measurement etc., is found to be negligible. The present invention allows obtaining accurate and precise sample system PSI and DELTA Values from an Ellipsometer System in which a polarized beam of light is oriented at other than a Principal of Brewster Angle of Incidence to a sample system, allows determination of DELTA values in ranges otherwise not impossible. allows determination of the "Handedness" of a polarized beam of light, and provides means for determining all of Stokes Vector and Mueller Matrix component values. The present invention also provides means for making all system components added to a conventional ellipsometer system essentially end user transparent when desired. without removal thereof from said ellipsometer system.