Optical balanced detection in heterodyne interferometric ellipsometry

The control of the state of polarization of a light wave for noise reduction is implemented as optical balanced detection in a common path heterodyne interferometer, which is presented in this work for measuring ellipsometric angles in real time. These angles are determined accurately in terms of quadrature interference amplitudes and phase information by maximum likelihood estimation. Thus, the interference noise is significantly reduced by the common path design associated with the optical balanced detection approach.