Analysis and extraction of misalignment errors in a three-in-one composite wave-plate with an equivalent fast axis

摘要

Misalignment errors of the composite wave-plate,a typical kind of compensator used in spectroscopic ellipsometers (SE),can lead to spurious oscillations in the SE measurement.In this paper,we construct an equivalent model of the three-inone composite wave-plate through mathematical derivation,and propose a method to analyze and extract the misalignment errors of the composite wave-plate.Obvious oscillations have been observed in the equivalent fast axis azimuth of the composite wave-plate through simulations,and these oscillations can be assigned to the angular misalignment errors between the individual plates of the composite wave-plate.The waveforms and amplitudes of the oscillations in the equivalent fast axis azimuth show high sensitivity to angular misalignment errors.Conversely,angular misalignment errors can be accurately extracted from the oscillations in the equivalent fast axis of the composite waveplate.It is expected that the proposed method for analysis and extraction of misalignment errors can be used to minimize angular misalignment errors and to improve the alignment procedure of the composite wave-plate.