ThreePIE unable to reconstruct 2-slice simulation

[yiranlus]

Hi everyone,

I try to reconstruct a 2-slice (slice distance 100 nm, electron ptychography under 80 kV) simulation with ThreePIE. The phases of the two objects are below:

I use a probe without any aberrations.

However, the reconstructed phase of the first slice is always very weak compared to the second slice. The phases of the two slices are like this:

Here are the parameter I used for the reconstruction:

engines:
  engine00:
    name: "ePIE_multislice"
    numiter: 100
    numiter_contiguous: 10
    alpha: 0.7
    beta: 0.5
    probe_update_start: 20
    record_local_error: false
    object_norm_is_global: true
    number_of_slices: 2
    slice_thickness: 100.0e-9

Anyone have idea why I can't get correct phase in this case?