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Phase Retrieval in py4DSTEM​

  • Suite of phase retrieval algorithms, including iterative DPC and Parallax
Virtual DarkFieldDifferential PhaseContrastParallax DepthSectioningIterativePtychography
Tutorial dataset from Y Jiang et al, Nature 559, 343 (2018)
User-friendly code 
  ptycho = SingleslicePtychographicReconstruction(
      datacube=dataset,
      energy = 80e3,
      semiangle_cutoff = 21.4,
  ).preprocess(
      fit_function = "plane", # de-scan correction
  ).reconstruct(
      max_iter = 8,
      step_size = 0.5,
      gaussian_filter_sigma = 0.3, # A
  ).visualize(
  )

Check out our tutorial notebooks here!
See also talk by Dr. Stephanie Ribet tomorrow (Wed July 26 @ 11:00am, Room 200B)

  • Iterative ptychography features:
    • Gradient-descent and projection-set algorithms
    • STEM-specific regularizations (e.g. real-valued potential object, probe aberration fitting, etc.)
    • Probe-position refinement
    • Hyperparameter tuning using Bayesian optimization
    • Mixed-state reconstructions (with orthogonal-probe-relaxation)
    • Single-slice and multi-slice reconstructions
    • Overlap tomography (joint ptychographic-tomographic) reconstructions
    • Simultaneous reconstructions for electrostatic and magnetic fields