Compound Refractive Lens Systems

Our CRL systems are divided into three main categories:

  • Water-cooled; for white, or pink, beams
  • Braid cooled; for pink or multilayer-monochromatic beams
  • Uncooled; for monochromatic beams

Compound Refractive Lenses are used as collimating or focusing elements in x-ray beamlines on FELs and synchrotrons. A CRL is typically used on a hard x-ray beamline with the lens material being Be, Al, or Ni as the energy increases. Since autumn 2019, lenses of single crystal diamond material have been available as well. The refractive lenses can either be shaped as a rotated parabola, and focus in 2D, or as a cylindrical parabola, and focus in 1D. To learn more about the offered lens options, please see our sections on standard lenses (Al, Be, and Ni) and diamond lenses.

A key feature of CRL focusing is that it is significantly less sensitive to vibrations than for instance mirror focusing: The moment transfer of a reflective mirror and a refractive CRL is given as below, where k is the wave vector,  ϑ is the incidence angle (or angular vibration), N is the number of lenses (typically between 10 and 100 lenses are used), and δ is the real part of refractive index (which is a material and energy-dependent number, but usually it is in the order of 10-6), see figure for a visual representation of the moment transfer:

Mirror                 Q = 2k sin ϑ

CRL                       Q = N½ k δ

By this, it can be deduced that lenses are in the order of at least, for all practical purposes, 100 times less sensitive to vibrations. The same principle can be applied to surface contaminations, so CRLs are basically insensitive to, for instance, carbon depositions.

Momentum transfer for mirror and CRL (figure is from RXOPTICS).

Various CRL types are offered (see pictures to the left). CRL systems are typically delivered with a five-way transfocator system offering; pitch, yaw, lateral, vertical, and longitudinal motion of the CRL vessel.

The systems are generally modular in design and can be scaled relatively freely. We also have smaller setups that are typically used for beam collimation.


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See also our poster with CRL systems.