Iterative reconstruction for snapshot intensity-modulated linear imaging spectropolarimetry without Fourier transform and phase calibration

Intensity-modulated linear imaging spectropolarimetry can measure a two-dimensional distribution of spectrally-resolved linear Stokes parameters in a single-shot polarization modulation. However, the state-of-art reconstruction method, Fourier transform method (FTM), usually transforms the modulated spectrum into the frequency domain for further processing. As a result, there is channel crosstalk issue that limits available frequency bandwidth. Then recovered spectra have artificial signals and the corresponding spectral resolutions are lower than the native resolution of the used spectrometer. In addition, FTM needs extra phase calibration to decode final spectra. In this paper, we present a continuous slide iterative method (CSIM) in the spectral domain for reconstruction to avoid the use of the Fourier transform and phase calibration. CSIM combines a sliding unit cell kernel in the spectral domain that provides unit cell tracking and a loop of two-step least-squares fit that estimates spatially-resolved polarized spectra. Both the simulations and experiments show that CSIM is more accurate and robust to noise perturbation, and can maintain the intrinsic resolution of the used spectrometer.