159 research outputs found
Shaping Coherent X-rays with Binary Optics
Diffractive lenses fabricated by lithographic methods are one of the most
popular image forming optics in the x-ray regime. Most commonly, binary
diffractive optics, such as Fresnel zone plates are used due to their ability
to focus at high resolution and to manipulate the x-ray wavefront. We report
here a binary zone plate design strategy to form arbitrary illuminations for
coherent multiplexing, structured illumination, and wavefront shaping
experiments. Given a desired illumination, we adjust the duty cycle, harmonic
order, and zone placement to vary both the amplitude and phase of the wavefront
at the lens. This enables the binary lithographic pattern to generate arbitrary
structured illumination optimized for a variety of applications such as
holography, interferometry, ptychography, imaging, and others.Comment: 9 pages, 4 figure
Fractal Generalized Zone Plates
The construction of fractal generalized zone plates (FraGZPs) from a set of
periodic diffractive optical elements with circular symmetry is proposed. This
allows us to increase the number of foci of a conventional fractal zone plate
(FraZP), keeping the self-similarity property within the axial irradiance. The
focusing properties of these fractal diffractive optical elements for points
not only along but also in the close vicinity of the optical axis are
investigated. In both cases analytical expressions for the irradiance are
derived. Numerical simulations of the energetic efficiency of FraGZPs under
plane wave illumination are carried out. In addition, some effects on the axial
irradiance caused by the variation in area of their transparent rings are
shown.Comment: Submitted to Optics Express, 200
Characterization of Spatial Coherence of Synchrotron Radiation with Non-Redundant Arrays of Apertures
We present a method to characterize the spatial coherence of soft X-ray
radiation from a single diffraction pattern. The technique is based on
scattering from non-redundant arrays (NRA) of slits and records the degree of
spatial coherence at several relative separations from one to 15 microns,
simultaneously. Using NRAs we measured the transverse coherence of the X-ray
beam at the XUV X-ray beamline P04 of the PETRA III synchrotron storage ring as
a function of different beam parameters. To verify the results obtained with
the NRAs additional Young's double pinhole experiments were conducted and show
good agreement.Comment: 15 pages, 6 figures, 2 tables, 42 reference
Ion beam lithography for Fresnel zone plates in X-ray microscopy
Fresnel Zone Plates (FZP) are to date very successful focusing optics for
X-rays. Established methods of fabrication are rather complex and based on
electron beam lithography (EBL). Here, we show that ion beam lithography (IBL)
may advantageously simplify their preparation. A FZP operable from the extreme
UV to the limit of the hard X-ray was prepared and tested from 450 eV to 1500
eV. The trapezoidal profile of the FZP favorably activates its 2nd order focus.
The FZP with an outermost zone width of 100 nm allows the visualization of
features down to 61, 31 and 21 nm in the 1st, 2nd and 3rd order focus
respectively. Measured efficiencies in the 1st and 2nd order of diffraction
reach the theoretical predictions
Combining scanning probe microscopy and x-ray spectroscopy
A new versatile tool, combining Shear Force Microscopy and X-Ray Spectroscopy was designed and constructed to obtain simultaneously surface topography and chemical mapping. Using a sharp optical fiber as microscope probe, it is possible to collect locally the visible luminescence of the sample. Results of tests on ZnO and on ZnWO4 thin layers are in perfect agreement with that obtained with other conventional techniques. Twin images obtained by simultaneous acquisition in near field of surface topography and of local visible light emitted by the sample under X-Ray irradiation in synchrotron environment are shown. Replacing the optical fibre by an X-ray capillary, it is possible to collect local X-ray fluorescence of the sample. Preliminary results on Co-Ti sample analysis are presented
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