Automatic Determination of Illumination Directions From Fourier Plane Images

This work explores the automated process of getting Fourier-domain shifts, the so called illumination directions, from Fourier plane images. These phase shifts are key in the implementation of modern iterative phase-recovery algorithms such as Fourier Ptychography Microscopy (FPM), Fourier Plane Imaging Microscopy (FPIM), and Dual Space Microscopy (DSM) of recent years. Incorrect illumination directions lead not only to a lack of improved resolution but, also no convergence of the phase of the light being diffracted from the sample being imaged. An algorithm has been developed that ascertains these illumination directions under a few key assumptions. These illumination directions are judged on correctness based on the synthetic Fourier plane formed in the program developed, and by implementation in FPM to see if magnitude and phase of the optical disturbance are recovered iteratively. The error of this process, along with errors shown in the implementation of DSM, are commented on with their impact in successful phase and magnitude recovery. Finally, further improvements to the algorithm developed and prospects for further generalization are discussed as future work to be done.

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