Zone-averaged method to minimize polarizer and analyzer imperfections in a phase-modulated spectroscopic ellipsometer

We have theoretically investigated the effects of polarizer and analyzer imperfections in a phase-modulated spectroscopic ellipsometer adopting a photoelastic modulator. Jones matrices having off-diagonal elements have been introduced to represent the imperfections of the polarizer and analyzer, and the effects of the imperfections were analytically derived to the first-order approximation. It was found that the effects of the imperfections could be completely eliminated by the zone average. Also, the effects of an incorrect setting of the modulation amplitude were found to be largely reduced by the zone average.