Aperiodic error correction for illumination array in Fourier ptychographic microscopy

Fourier ptychographic microscopy obtains high-frequency information beyond the cutoff frequency of the objective lens by multi-angle illumination, and reconstructs large field-of-view and high-resolution images via spectrum stitching and phase retrieval. High-quality imaging of FPM requires accurate stitching of sub-aperture spectra corresponding to different illumination angles. Existing work typically designs optimization algorithms to compensate for the misalignment of sub-aperture spectra caused by the overall error of the illumination array. However, aperiodic error of the illumination array’s geometry arrangement induced during the actual manufacturing leads to inaccurate stitching of sub-aperture spectra, and consequently causes artifacts in the reconstructed images. This work proposes an aperiodic error correction method for FPM illumination modes based on prior information of illumination array’s geometry arrangement. The relative positions of each illuminating unit are measured and the measured geometry of the illumination array is used to secure accurate stitching of sub-aperture spectra corresponding to different illumination angles. Simulation and experimental results show that artifacts in the reconstructed images caused by the aperiodic error are suppressed and the resolution line pairs contrast is improved by the proposed method. The proposed method requires only a one-time measurement of the illumination array without introducing any computational complexity. It offers a simple approach to accurately compensate for sub-aperture misalignment, enabling high-quality Fourier ptychographic microscopy.