Algorithm for compensating the impact of an imperfect quarter-waveplate in a parallel four-step phase-shifting digital holography

We propose and experimentally demonstrate an algorithm for parallel four-step phase-shifting digital holography that compensates for the imperfections of a quarter-waveplate to improve the quality of reconstructed images. We introduce two parameters to quantify the imperfectness of a quarter-waveplate and determine these parameters using the reference wave alone. The object wave is then reconstructed using these parameters, resulting in significantly improved object images. The method shown here should be useful for phase-shifting digital holography, utilizing the combination of a polarization camera and a quarter-waveplate, especially when light waves with multiple wavelengths are involved.