Fabrication of parabolic nanofocusing x-ray lenses

We have fabricated planar parabolic lenses made of silicon and boron which have a focal distance in the range of a few millimetres at hard x-ray energies. Two silicon lenses were used in a crossed geometry to generate a microbeam with a lateral size of 160x107 nm 2 at 15 keV. The focus size of 180 nm at 22 keV and at a distance from the synchrotron radiation source of 42 m was obtained with boron lens. The performance of the silicon lenses was improved by optimising the e-beam lithography and the etching parameters. In addition, we report on the microfabrication process of diamond as well as pyrolytic graphite lenses.