Many applications in the field of X-ray analytics require an X-ray beam with a high flux density at the sample position. Examples for these applications are single crystal diffraction or micro-diffraction to name but a few. An X-ray system comprising of an X-ray source with a small electron beam spot size combined with a diffracting 2-dimensional multilayer mirror is the ideal source for these applications. The mirror collects many photons from the small source, especially when it is mounted as close to the source as possible.
To achieve the goal of a high flux density the spot size on the anode of the X-ray tube should be as small as possible with a simultaneous increase of the X-ray power. A risk is the melting of the anode due to weak heat dissipation. At the same time the figure error of the multilayer mirror should be as low as possible. Large figure errors will increase the spot size of the X-ray beam at the sample position.
X-ray sources according to the principle of the "free electron laser" (FEL), will in future, be able to provide bright
radiation with pulses in the femtosecond range. Even nowadays, home-lab X-ray sources with very short pulses in the
sub-picosecond range are already available for lab experiments. These laser-based sources need different kinds of optics
to direct the emitted X-rays onto the samples. On the one hand, the optics should transfer as much flux as possible and
on the other hand, the brilliance and timestructure of the source should not be reduced too much. These requirements are
fulfilled with 2-dimensional beam shaping multilayer optics. Their design, production and their influence on the shape of
the X-ray beam will be explained in this contribution. The optics consist of bent substrates with shape tolerances below
100 nm, upon which multilayers are deposited with single layer thicknesses in the nanometer range and up to several
hundreds of pairs of layers. Furthermore, these multilayers were designed with lateral thickness gradients within ± 1%
deviation of the ideal shape. This means that a deposition precision in the picometer range is required. We use
magnetron sputtering methods for deposition, optical profilometry in order to characterize the shape of the optics and X-ray
reflectometry to characterize the multilayers.
Current and next-generation light sources, for instance third generation synchrotron sources, FLASH and the future project X-FEL require single-layer and multilayer mirrors with an active optical length of more than one meter. At the GKSS research centre, a new sputtering system for the deposition of single-layer and multilayers has been installed. This new system is able to manufacture mirrors with a maximum deposition length of 1.5m. In this paper we are going
to present the first results of this challenging system. The mirror properties are investigated by means of X-ray reflectometry, transmission electron microscopy and interference microscopy. The performance of the mirrors is analyzed, considering X-ray reflectivity, film thickness, micro-roughness and the uniformity of these properties over the whole deposition length. The results will be discussed and compared with former results.
Selected aspects of simulation, preparation and characterization of total reflection and multilayer X-ray optics will be
discussed. The best multilayer is found by calculating the optical properties of the coating. Sophisticated improvements
in deposition technology allow the precise realization of the specified parameters when manufacturing the X-ray optics.
The quality of the shape of the substrate for the optics is measured with the aid of profilometry. X-ray reflectometry
measures both film thickness as well as their lateral gradient. Last but not least we will be showing results of the
development of carbon coatings as total reflection mirrors for FEL (free electron laser) sources. Over the past years we
have developed optimized optics for the XUV range up to 200 eV. First FEL irradiation tests have shown that carbon
coatings offer high reflectivity > 95%, high radiation stability, good uniformity in thickness and roughness. An
optimized coating of two stripes for different beam energies was produced especially for a tomography beamline, where
a Ru/C multilayer was chosen for energies between 10 and 22 keV and a W/Si multilayer for energies between 22 and 45 keV.