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. 2018 Jun 17;25(Pt 4):1048–1059. doi: 10.1107/S1600577518007208

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© Li and Jacobsen 2018

This is an open-access article distributed under the terms of the Creative Commons Attribution (CC-BY) Licence, which permits unrestricted use, distribution, and reproduction in any medium, provided the original authors and source are cited.

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Effect of using both stacked and refocusing zone plates. Four combinations were compared: a conventional zone plate alone (C), or optionally with a stacked zone plate (S), or optionally with a third diffraction order refocusing zone plate (R3). This gives combinations C, CS, CR3 and CSR3 as indicated. On the left (a) is shown the focused intensity profile and radial integral of energy, while on the right (b) is shown the set of axial intensity profiles. Adding a refocusing zone plate provides some increase in focused intensity, but only over a narrow depth of focus range reduced by a factor of due to the presence of the third diffraction order refocusing zone plate (R3). The parameters for the individual zone plates are shown in Table 3 ▸.

Inline graphic — Effect of using both stacked and refocusing zone plates. Four combinations were compared: a conventional zone plate alone (C), or optionally with a stacked zone plate (S), or optionally with a third diffraction order refocusing zone plate (R3). This gives combinations C, CS, CR3 and CSR3 as indicated. On the left (a) is shown the focused intensity profile and radial integral of energy, while on the right (b) is shown the set of axial intensity profiles. Adding a refocusing zone plate provides some increase in focused intensity, but only over a narrow depth of focus range reduced by a factor of due to the presence of the third diffraction order refocusing zone plate (R3). The parameters for the individual zone plates are shown in Table 3 ▸.