The moving-beam diffraction geometry: the DIAD application of a diffraction scanning probe

Leonardi, A.; James, A.; Reinhard, C.; Drakopoulos, M.; Williams, B.; Dehyle, H.; Filik, J.; Perera, L.; Ahmed, S.

doi:10.1107/S1600576725009811

Figure 12
Nearest-neighbor moving-beam geometry calibration error. Interplanar-distance error estimated with the nearest-neighbor calibration relative to the average of those estimated from the reference self-calibrated diffraction geometry for flat-plate NIST SRM 660b LaB₆, mapped on the imaging FOV (2580 × 2180 pixels). The test diffraction data are reduced using the geometry calibrated for the nearest-neighbor standard diffraction from regular Cartesian grids of (A), (B) 40 × 36, (C), (D) 20 × 18 and (E), (F) 10 × 9 beam offsets across the FOV. The diffraction beam moves across the imaging FOV on a Cartesian grid with a half-step offset compared with the denser calibration grid. The study is repeated with the detector positioned [(A), (C) and (E)] with conventional transmission geometry (i.e. $[\alpha = 0^\circ]$ , $[\beta = 0^\circ]$ , $[\gamma = 0^\circ]$ and $[r = 330 \ {\rm mm}]$ ) and at a standard experiment configuration [(B), (D) and (F)] shifted inboard without any tilt to allow room for the imaging camera to be in view of the sample (i.e. detector panel orthogonal to the incident-beam direction, and the pixel at the center of the detector panel at $[\alpha = \ \sim\!17^\circ]$ , $[\beta = \ \sim\!13^\circ]$ , $[\gamma =\ \sim\!4^\circ]$ and $[r = 660 \ {\rm mm}]$ ). The independent self-calibrated diffraction geometry yields an s.d. of 0.008 (1)% and ∼0.006 (5)% for the two detector configurations (Table 5

), respectively.

JOURNAL OF
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CRYSTALLOGRAPHY

ISSN: 1600-5767

Volume 59| Part 1| February 2026| Pages 12-27

https://doi.org/10.1107/S1600576725009811

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