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![[Figure 1]](gui5004fig1mag.jpg)
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Figure 1
Simulations of phase retrieval algorithms applied to projections of a two-material phantom. This phantom is composed of low-Z PMMA embedded with spherical cavities (white arrow) and a high-Z aluminium cylinder which appears as a dark column in the exit surface wavefield shown in (a). Panel (b) shows the phase contrast image produced from free-space propagation via the TIE to produce Fresnel fringes at each boundary that vary in amplitude according to the materials present. Here, noise is added to simulate low-flux imaging. (c) Single material phase retrieval with equation (1) ![[link]](../../../../../../logos/arrows/s_arr.gif){kind=small} , using δ and μ for PMMA, showing accurate restoration of the low-Z/air boundaries [cf. panel (a)] but severely over-blurs the high-Z material and the surrounding area. This can be avoided with (d) two-material phase retrieval to the high-Z, low-Z interface, using equation (3) with the δ and μ values for the low-Z (PMMA) and high-Z (Al) materials, but at the expense of higher remnant noise and phase contrast fringes left around the low-Z/air boundaries of each cavity. An ideal approach would achieve the benefits of both approaches shown in (c) and (d). |
![[Figure 1]](gui5004fig1.jpg)
 | JOURNAL OF SYNCHROTRON RADIATION |
ISSN: 1600-5775
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