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Structure in defocused beams of x-ray mirrors: causes and possible solutions

DOI: 10.1117/12.2061941 DOI Help

Authors: John Sutter (Diamond Light Source) , Simon Alcock (Diamond Light Source) , Fiona Rust (University of Bath) , Hongchang Wang (Diamond Light Source) , Kawal Sawhney (Diamond Light Source)
Co-authored by industrial partner: No

Type: Conference Paper
Conference: SPIE 9208 Adaptive X-Ray Optics III
Peer Reviewed: No

State: Published (Approved)
Published: September 2014

Open Access Open Access

Abstract: Grazing incidence mirrors are now a standard optic for focusing X-ray beams. Both bimorph and mechanically bendable mirrors are widely used at Diamond Light Source because they permit a wide choice of focal lengths. They can also be deliberately set out of focus to enlarge the X-ray beam, and indeed many beamline teams now wish to generate uniform beam spots of variable size. However, progress has been slowed by the appearance of fine structure in these defocused beams. Measurements showing the relationship between the medium-frequency polishing error and this structure over a variety of beam sizes will be presented. A theoretical model for the simulations of defocused beams from general mirrors will then be developed. Not only the figure error and its first derivative the slope error, but also the second derivative, the curvature error, must be considered. In conclusion, possible ways to reduce the defocused beam structure by varying the actuators' configuration and settings will be discussed. © (2014) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.

Subject Areas: Technique Development

Instruments: B16-Test Beamline , I02-Macromolecular Crystallography