Double Crystal Monochromator | FMB Oxford

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Double Crystal Monochromator

Double Crystal Monochromator


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FMB Oxford has unparalleled expertise in customised hard x-ray monochromators, having designed and constructed more than 80 since the first unit was delivered to the ALS in 1996.

The FMB Oxford DCM, the leading monochromator for hard X-ray applications, is a versatile high performance system suitable for use on both bending magnet, wiggler and undulator beamlines. The spectral range required determines the choice of crystals; multiple sets of crystals can be installed, with in-vacuum selection. The system can be used in either fixed offset or pseudo-channel cut mode. We can provide either water-cooling or cryo-cooling for the first crystal, depending on the heat load to be dissipated and the thermal and optical performance required. We offer a range of second crystal designs: short second crystals with parallel translation; long second crystals which allow the beam to walk the length during Bragg rotation; and sagittally bent second crystals for focusing.

The DCM consists of the vacuum system, goniometer, crystal support, and manipulation mechanism, mounted on a substantial synthetic granite block. The associated electronics can be supplied mounted in a 19” rack system.


  • UHV design and manufacture throughout
  • High precision rotary table goniometer for Bragg angle rotation
  • Crystal cage mounted on rigid drive shaft for exceptional stability
  • Goniometer supported on synthetic granite plinth for superior vibrational damping
  • Slide mount for goniometer allowing easy removal when vacuum chamber is open
  • Axis of goniometer large enough to accommodate both water and cryogenic feedthroughs
  • Crystal cage configurable for vertical offset, with exit beam higher or lower than input beam
  • Compact footprint
  • Fine pitch and roll controls


  • Standard Sagittal bender
  • Enhanced Sagittal bender
  • Set of Crystals
  • Non-standard offset
  • Non-standard Bragg Angle range
  • Motorised support feet with precision hard stop
  • Multiple mounted crystal sets with in vacuum crystal translation
  • Multiple mounted crystal sets with in air crystal translation
  • Turntable to allow goniometer to rotate once withdrawn from vacuum vessel
  • Motorised first crystal roll
  • First crystal in vacuum vertical translation
  • Controllers for translation motors
  • Compton shielding
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