Structure in defocused beams of X-ray mirrors: Causes and possible solutions

John P. Sutter, Simon G. Alcock, Fiona Rust, Hongchang Wang, Kawal Sawhney

Research output: Chapter or section in a book/report/conference proceedingChapter in a published conference proceeding

13 Citations (SciVal)


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.

Original languageEnglish
Title of host publicationProceedings of SPIE - The International Society for Optical Engineering
ISBN (Print)9781628412352
Publication statusPublished - 2014
EventAdaptive X-Ray Optics III - San Diego, UK United Kingdom
Duration: 17 Aug 2014 → …


ConferenceAdaptive X-Ray Optics III
Country/TerritoryUK United Kingdom
CitySan Diego
Period17/08/14 → …


  • Defocus
  • Error
  • Figure
  • Mirror
  • X-ray


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