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polished and unpolished C* lenses and a slightly higher 1.1 µm for the Be lenses. The polishing increased the higher order spherical aberrations, as seen in the circular features of Figure 145b.

The three CRL stacks were installed on beamline ID06 to characterise the beam focusing in the focal plane and its vicinity. The results showed an improvement of performance when the C* lenses were polished, and they performed as well as the Be lenses in terms of beam size in the focal plane. Measured beam sizes in focus depend on several experimental parameters. Under the experimental conditions here, a beam size of 0.98 µm x 1.61 µm was achieved for the polished C* stack (Figure 145c) and 0.98 µm x 1.55 µm for the Be CRL. The focusing behaviour can be reproduced by simulations using XSVT metrology [5].

Furthermore, since the diamond lenses are made of single crystalline plates, they exhibit a much smaller small- angle X-ray scattering (SAXS) signal when compared to Al or Be lenses. This leads to a cleaner beam profile with less intensity around the optical axis, as shown in Figure 145d. SAXS evaluation was performed on ID02.

Diamond lenses are a general alternative to Be lenses when focusing a monochromatic beam, especially above 20 keV, when their higher absorption is less significant. They are also ideal for operation in white beam when used as collimating optics upstream of high-resolution monochromators, and potentially as a final focusing element in pink-beam experiments. Finally, due to the manufacturing process, lens radii (focusing strength) can be finely selected as opposed to pressed Be or Al lenses, which come in a few pre-selected radii.

PRINCIPAL PUBLICATION AND AUTHORS

Polished diamond X-ray lenses, R. Celestre (a), S. Antipov (b), E. Gomez (b), T. Zinn (a), R. Barrett (a), T. Roth (a), J. Synchrotron Radiat. 29, 629-643 (2022); https:/doi.org/10.1107/s1600577522001795 (a) ESRF (b) PALM Scientific, Bolingbrook (USA) formerly at Euclid Techlabs

REFERENCES

[1] A. Snigirev et al., Nature 384, 49-50 (1996). [2] T. Roth et al., MRS Bulletin 42, 430-436 (2017). [3] Y. Shvyd ko et al., MRS Bulletin 42, 437-444 (2017). [4] S. Berujon et al., J. Synchrotron Radiat. 27, 293-304 (2020). [5] R. Celestre et al., J. Synchrotron Radiat. 27, 305-318 (2020).