Figure 3
From: Low-dose three-dimensional hard x-ray imaging of bacterial cells
2D projections of D. radiodurans. Holographic intensity diffracted from freeze-dried D. radiodurans cells at rotation angles (a) θ = 80° and (c) θ = 0°, normalized by the empty WG far-field intensity distribution. (b,d) Corresponding phase reconstructions obtained with a modified HIO scheme as described in the main text. The coloring is scaled in rad and also mg/cm2. (e) Angular averaged power spectral density (PSD) of the phase reconstruction shown in (d) plotted as a blue line, together with the phase-contrast transfer function (PCTF). In comparison to the PSD of a single-step holographic reconstruction, shown as a red line, the modified HIO scheme recovers spatial frequencies, where the PCTF is zero. A fit of an exponential power law to the PSD in the interval [0.1,3] μm-1 is shown as a dashed black line. The transition point to the noise plateau, shown as a solid black line, is at 4 μm-1. (f) 2D projection of the tomographic 3D dataset of the cells, obtained by numerical evaluation of line integrals corresponding to a rotation angle θ = 0°.