From Tomographic Phase Retrieval to Projection Tomography

Albert Fannjiang
University of California, Davis (UC Davis)

We analyze measurement schemes under which 3D unwrapped phase retrieval can be reduced to projection tomography. A key component is the deployment of a coded aperture.

Our motivation is to leverage highly successful projection-based techniques in cryo-EM to process diffraction data collected under measurement uncertainties such as sample heterogeneities, unknown orientations and positions.

First, with the introduction of a beam splitter, the dataset of diffraction patterns is reducible to that of projections under measurement uncertainties.

Second, without a beam splitter, this data reducibility holds true for random conical tilt and orthogonal tilt schemes widely used in cryo-EM.

Finally, the resulting phase unwrapping problem for 3D projection tomography can be solved by schemes including as special cases the conical tilting at a conical angle slightly greater than pi/4, the orthogonal dual-axis tilting and a combination of a conical tilting and an orthogonal single-axis tilting.

Back to Workshop I: Diffractive Imaging with Phase Retrieval