Deep reactive ion etching of silicon and diamond for the fabrication of planar refractive hard X-ray lenses

We report on the fabrication of diamond and silicon refractive X-ray lenses. These are made using e-beam lithography and deep reactive ion etching. The diamond lenses are promising candidates for optics meeting the extreme requirements of planned X-ray sources based on the free electron laser principle. The silicon lenses are well suited for micro-focusing applications at hard X-ray energies above 20 keV. We measured efficiencies up to 78% and a width of the line-focus down to 3 μm for these lenses. The possibility to compensate for lens aberrations using stacked lenses is discussed. A simple method for the stacking of two silicon devices (lenses) by means of micro-mechanical alignment marks is shown, giving an alignment accuracy in the micron range. © 2003 Elsevier Science B.V. All rights reserved.