A monochromator for tuning the photon energy range 600 eV and 6000 eV with a single dispersing optical element (Conference Presentation)

Recently it was found that reflection gratings of standard quality, which can be used at lower energy soft X-rays with photon energies of the order of 300 eV, diffract also efficiently X-rays with photon energies of the order of 5 keV, when these gratings are operated at grazing angle of incidence in the extreme off-plane configuration [1]. Consequently a grating employed in the extreme off-plane configuration has the capability to provide monochromatic radiation in the photon energy range from below 1 keV to far above 2 keV, where one usually switches for the same purpose between the diffraction at surface structures and the diffraction in bulk structures. Such an operation scheme requires rather complex mechanical structures. The present study will show that the tuning of diffraction gratings in the conical diffraction configuration can cover the indicated and even more extended tuning ranges employing a rather simple mechanical structure. Infact such a grating can be mounted together with a plane mirror in a pseudo channel-cut crystal monochromator configuration, i.e. with almost parallel surfaces and with fixed gap between them. The photon energy is then tuned simply by varying the angle of grazing incidence onto the pair of optics. Like in a double crystal monochromator scheme the monochromatic beam will exit from the configuration parallel to the incident beam with in most cases negligibly varying displacement in the plane of incidence. The optical performance data will be discussed depending on the properties of some state-of-the-art synchrotron radiation sources. [1] W. Jark and D. Eichert, Opt. Express 23, 22753 (2015).