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Figure 2
Sample positions within a crystallization plate as determined using X-ray diffraction grid scans (the contour plots represent crystal X-ray diffraction strength) and using visible light through the on-axis microscope, which is subject to refraction effects that systematically shift the apparent crystal location. (a) and (b) show series of three images recorded with ω equal to −3°, 0° and 3°. The images in (a) were recorded with the sample-rotation axis position in the nominal OAV focal plane, whereas the images in (b) were recorded with the axis of rotation translated 400 µm downstream into the new focal plane of the OAV–plate combination. Note that in (a) the crystal appears visually to remain centred when rotated, but the diffraction data confirm that it is in fact drifting off-axis. In (b) the crystal appears to translate vertically when rotated, but X-ray diffraction confirms that is correctly centred on the axis of rotation.

Journal logoSTRUCTURAL
ISSN: 2059-7983
Volume 68| Part 5| May 2012| Pages 592-600
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