Hourglass Pattern Recognition Algorithms in Vortex Polarimetry: A Review With Quantitative Evaluation

Vortex retarder, a typical spatial polarization modulation device, encodes incident light’s polarization information into characteristic patterns, with pattern recognition accuracy determining polarization direction (PD) and Stokes vector measurement precision. This article reviews eight representative algorithms [local morphology, radon transform (RT), correlation, and frequency domain decomposition (FDD)] and conducts multidimensional quantitative comparisons (accuracy, efficiency, and so on) via static and dynamic experiments. Results confirm FDD’s superiority in complex scenarios and high-order vortex retarders, and provide practical technical guidance for algorithm selection for polarization measurement community.