The instrument allows to orient a number of strips in such a way that they approximatively form together a part of a cylinder. The radius of this cylinder can be varied from 500 mm to ∞.
If one chooses –as strips- appropriate single crystals (for ex. Cu or Pyrolytic Graphite HOPG) the apparatus is used as a focussing monochromator or analyzer.
Horizontal bending allows focussing in the k-space which improves the resolution of a measurement.
Vertical bending allows focussing in the real space which increases the neutron flux at the sample, so at the detector position.Description :
The instrument consists of a rotation shaft on which high precision profiled discs are located one for each crystals strip. Rotation of the shaft causes rotation of the crystals by means of lever arms which are connected to the discs. Their profiles are realized in such a way that the whole crystal arrangement approximates a cylindrical surface.
Each strip is adjustable in two directions. For the “infinit radius” all strips are located in the same plane.
The focussing radius is changed by turning the disc axis (usually by a stepping motor) and measured by an encoder.
The instrument can accept each kind of crystals. For heavy materials it is however recommended to hold the strips in bearings at both sides. Then the instrument has to be mounted into a frame (on request).