Polychromatic polarization-based shearing interferometry with channel-selective phase-gradient recovery

A polarization-encoded interferometric system operating under broadband illumination is presented for retrieving the optical phase derivative of static and time-varying transparent samples in a single exposure. The setup employs a polarized cyclic-path interferometer (PCPI) combined with a replication stage, enabling the generation of four phase-shifted interferograms with nominal π/2 steps. Although a white-light source is used, the phase reconstruction is performed independently per color channel after RGB separation, which allows channel-specific monochromatic processing without axial scanning. The green and red channels exhibit sufficient fringe visibility for phase retrieval, whereas the blue channel presents limited sensitivity due to spectral attenuation and camera responsivity. Therefore, the method functions effectively as a two-wavelength channel-selective interferometer, rather than a full multiwavelength interferometric system. A stability and repeatability assessment with 100 measurements confirmed the robustness of the proposed approach. Experimental results with static aberrated samples and dynamic optical events demonstrate the feasibility of real-time phase-derivative sensing under broadband illumination without mechanical scanning.