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Methoden und Instrumentierung Poster: Mi., 14:00–16:30 M-P60
Planar set of refractive lenses for hard X-ray micro spectroscopy and imaging
Vladimir Nazmov 1 , Elena Reznikova 1 , Arndt Last 1 , Jürgen Mohr 1 , Volker
Saile 1
1 PO. 3640, 76021 Karlsruhe
X-ray planar refractive lenses from SU-8 polymer and nickel have been developed during
the last four years at the IMT / FZK, Karlsruhe. The lenses are manufactured
using the LI-thography and electroplating-G steps of the LIGA-technique. By perpendicular
respectively 45 ◦ -tilted X-ray patterning linear respectively crossed lenses can
be formed to obtain a linear or a point-like focal spot. The set designed for crossed
parabolic lenses structured in the SU-8 polymer includes 17 parallel rows of a large
number of lens elements with different curvature radii and apertures. The possibility
of mechanically removing elements allows adapting the lenses of the set to any experimental
requirements. For example, synchrotron radiation with different photon
energies can be focussed on identical focal distance. Due to the low atomic number of
the atoms of SU-8 polymer, the transparency of the lenses is ∼ 0.7 with a maximal
efficiency in the range of 12-30 keV. Together with X-ray lenses with a parabolic shape,
using E-beam writing, lenses with mosaic and quasi-parabolic shapes are created, to
increase the photon flux (4 times) and increase focal depth (50 times), respectively.
For the previous testing experiments, the linear lenses formed the focal line of 105
nm width at 15.85 keV, and the cross lenses provided 0.4 x 0.8 µm 2 focus spot at
28 keV. The very large demagnification by means of the crossed lenses resulted in an
intensity gain of more than 50000. In comparison with Be-lenses, the very compact
arrangement of crossed SU-8 micro structure lens elements provides a focal distance of
several millimetres that allows focusing X-rays from synchrotron radiation sources of
different generations to a nanoscale beam.
The cross lenses were used for X-ray imaging of micro objects with a spatial resolution
of less than 0.3 µm in phase contrast mode. A magnification up to 150 was
achieved. The results of the lens characterisation at ANKA and at ESRF are presented
together with examples of lens applications like X-ray µ-spectroscopy and magnified
X-ray imaging.
Fig. 1: Row of crossed parabolic lenses