X-ray laser facilities are being constructed all over the world: Linac Coherent Light Source (LCLS) in California,
RIKEN X-Ray Free-Electron Laser at SPring-8 in Japan, European XFEL in Germany etc. XFEL is the next-generation
(4th) light source. However, the number of such experimental facilities (SRS and FEL) is quite limited. At the same
time, relatively small vacuum ultraviolet laboratories with impulse sources [High Harmonic Generators (HHG)] allow
one conduct in-house research. This makes the research community directly involved in experiments with time resolution
much wider. The latest radiation sources and modern physical experiments require application of the newest diffractive
elements. Such diffractive elements are required for implementation of experiments with time resolution using
synchrotron radiation sources or high harmonics generators. For example, valence state evolution or molecules
dissociation in time-resolved investigation. Modern experiments like this might require implementation of time
resolution in femto - (10-15) and even atto- (10-18) seconds.
The 2-Dimensional and 3-Dimensional variable line spacing (VLS) gratings based on total external reflection give the
unique possibility for spectroscopy and focusing in application to 4th and 5th generation synchrotron sources. We focus
on the elaboration of novel approaches for design and fabrication of 3D VLS working in the entire energy range, from
THz to hard X-rays. These optical elements have unique combination of properties and can operate at all XUV sources
including Free Electron Lasers (FELs), Energy Recovery Linacs (ERLs) and High Harmonic Generators (HHGs). Such
3D DOEs are able to cover the energy range of up to 20 keV with energy resolution λ/Δλ ≥ 1000 for soft x-ray and λ/Δλ
≥ 10000 for hard x-ray. We fabricate 3D VLS for time-resolved spectroscopy (energy range 100 – 2000 eV, 7500-9500
eV), FELs and ERLs (energy range up to 3 keV), and HHGs (energy range 10 – 200 eV).
Reflection zone plates (RZP), which consist of elliptical zone plates fabricated on a total external reflection mirror surface, can be effectively used to produce a monochromatic x-ray beam and to focus it at photon energies below 1400 eV. However, as RZPs are highly chromatic, they can be designed only for one specific photon energy. We alleviate this problem by using a novel approach: a Reflection Zone Plate Array (RZPA). Here, we report about successful implementation of novel monochromator based on RZPAs for experiments with 100 fs time resolution at the upgraded Femtoslicing facility at BESSY-II. Aiming at minimum losses in x-ray flux up to 2000 resolution, we fabricated and used an RZPA as a single optical element for diffraction and focusing. Nine Fresnel lenses, designed for the energies of 410 eV, 543 eV, 644 eV, 715 eV, 786 eV, 861 eV, 1221 eV and 1333 eV which correspond to the absorption edges of NK, O-K, Mn-L, Fe-L, Co-L, Ni-L, Gd-M and Dy-M, were fabricated on the same substrate with a diameter of 100 mm. At resolution E/ΔE up to 2000 all edges of other elements in that range (400-1400 eV) are covered, too.
Dedicated diffractive VUV- and X-ray optical elements are essential for future developments in synchrotron instrumentation and methods like e.g. time-resolved spectroscopy. The quality of optical components like gratings or diffractive focusing elements matters directly to the results achievable. On the other hand the availability of such optical components is very limited at present. In this contribution we report on the development of new methods of time-resolved x-ray spectroscopy based on novel 3D diffractive optical elements (DOE) with a unique combination of properties. Such optical elements are of highest interest for application in modern synchrotron facilities like Free Electron Lasers (FELs) as well as for laboratory facilities with high harmonic generators (HHG). The project includes theoretical work as well as the development of a dedicated technology, including metrology, to manufacture such type of optics for applications in atomic, molecular and condensed matter physics. The here discussed type of optics was successfully implemented for soft-X-ray-application at the femto-second-slicing beamline at BESSY II storage ring of the Helmholtz Zentrum Berlin. DOE are expected to be important components in beamlines at upcoming new high brilliance X-ray sources such as FELs. The application of DOE`s allows to reduce the number of optical elements in a beamline. Thus allow to provide the highest possible transmission and flux as well as preserving the unique properties of FEL´s, like wave-front and coherence.
The concept of the design and fabrication of X-ray diffraction focusing elements is discussed. This concept includes both reflection and transmission types of optics as well as equipment necessary for their fabrication.
Systematic experimental investigations of Bragg-Fresnel gratings are discussed. Gold and nickel masks with periods of 0.4 μm n 5 μm were evaporated on the surfaces of Si  symmetric and asymmetric crystals. These have been used to obtain x-ray diffraction in the energy range of 8000 eV n 8500 eV. A theoretically calculated maximum of diffraction efficiency of the order of 30 % was measured experimentally for gratings with grooves parallel to the beam direction (sagittal gratings). Diffraction effects in the crystalline substrate for the gratings with grooves perpendicular to the beam direction (meridional gratings) limit the diffraction efficiency on the order of a few percent. Experimental data are compared with the theoretical calculations dispersion and efficiency of Bragg-Fresnel gratings.