Hard x-ray imaging by Multilayer Zone Plates

Degrees of Freedom for sample alignment

The sample can be pre-aligned using optical microscopes; the position of the x-ray beam is known with a precision of a few µm. Alignment is carried in x,y,z direction with the M-686 and N-765 stages, first in a large defocus / working distance to the MZP to ease manoeuvring.

This pre-alignment is usually done with many (actual) eyes on the sample, to prevent crashing of the sample stage with the microscopes or – worse – the zone plate.

Sample alignment is also supported by x-ray scans with the primary beam (with MZP moved out slightly) or in holographic mode with the MZP and a large field of view.

Finally, the sample is moved in x-direction – slowly and with care – towards the MZP; the working distance is checked with the depth of focus of the in-line microscopes and a lateral macro camera.

M-686 and N-765 motors moved to extreme positions (Rendering).

FIXME: See also this animation showing the typical movements during sample alignment.