Silicon planar lenses for high-energy x-ray nanofocusing

Optimizing the lens design and improving the technological process, we manufactured X-ray planar compound refractive lenses with vertical sidewalls up to 70 microns deep. The lens surface roughness in the order of 20 nm was attained. The minimal thickness of the material between two individual lenses of 2 µm was realized. Driven by the requirements of new 100 m-long beamlines at the ESRF, the first prototype chip of Si planar nanofocusing lenses was designed and manufactured. The technological breakthrough allows to reach the nanometer focusing. The optical tests of the new planar lenses were performed at the ESRF beamlines BM5 and ID15. The resolution below 200 nm was measured in the energy region of 15-80 keV. The best resolution of 150 nm was demonstrated at 50 keV energy. As a next step dedicated chip design for two-dimensional focusing with nanopositioning stages will be realized.