Open AccessMeasuring the criticality of the `magic condition' for a beam‐expanding monochromator
Author(s) -
Martinson Mercedes,
Chapman Dean
Publication year - 2016
Publication title -
journal of synchrotron radiation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.172
H-Index - 99
ISSN - 1600-5775
DOI - 10.1107/s1600577516012650
Subject(s) - monochromator , optics , physics , beam (structure) , coherence (philosophical gambling strategy) , bent molecular geometry , limiting , materials science , wavelength , mechanical engineering , quantum mechanics , composite material , engineering
It has been established that for cylindrically bent crystals the optimal beam characteristics occur when the geometric and single‐ray foci are matched. In the beam‐expanding monochromator developed for the BioMedical Imaging and Therapy beamlines at the Canadian Light Source, it was unclear how critical this `magic condition' was for preserving the transverse coherence of the beam. A study was conducted to determine whether misalignments away from the ideal conditions would severely affect the transverse coherence of the beam, thereby limiting phase‐based imaging techniques. The results were that the magic condition has enough flexibility to accommodate deviations of about ±1° or ±5 keV.