Accurate reconstruction of polarization parameters for channeled spectroscopic Stokes polarimeters

In this work, we present an accurate polarization reconstruction method based on the coherence demodulation technique, which is different from the previous windowing method operating in the optical path difference domain. The proposed method uses a signal multiplier and a low-pass filter to reconstruct Stokes parameters without performing any Fourier transform. Because this method does not require a Fourier transform, the Stokes reconstruction could be finished in the spectral domain. For calibrating the waveplate phase error, coherence demodulation allows for establishing an analytical model to describe the influence of waveplate imperfections on the polarization measurement process. The phase error will result in a channel shift and Fourier broadening, both of which cause serious errors during Stokes reconstruction. With the model, a method based on a linear polarizer was proposed for calibrating the phase deviation of waveplate. After that, the accurate reconstruction of polarization parameters could be achieved. An experiment was performed to check the ability of the proposed method. The experimental result showed that it has the same excellent performance of reconstructing Stokes parameters using the traditional windowing method. Finally, a series of simulations was carried out to verify the robustness of this method, which showed that the reconstruction technique is robust to misalignment and additional noise.