Mono (Bestek)

The design of the CASSIOPEE plane grating monochromator was done by the SOLEIL Optics Group. The starting point is the famous SX700 monochromator, but several modifications have been made by the Optics Group.
The working principle of the monochromator is sketched in the figure below. One can choose the incident angle α of the white beam on the plane grating by rotating the grating around an horizontal axis. The β angle can be chosen by rotating the plane mirror, above the grating, around a horizontal axis located below the grating plane, to ensure a constant height of the outgoing beam. For a given couple (α,β), the selected wavelength λ is given by the gratings law:

to ensure an optimal resolution on the whole photon energy range.

Caption: Principle of the CASSIOPEE monochromator.

Caption: Picture showing the inside of the CASSIOPEE monochromator, with the plane mirror cage above the four available grating cages. The monochromator was built by the BesTec company (Berlin, Germany).