X-ray transmission lenses by deep x-ray lithography and LIGA technique: First results and fundamental limits.

Today's dimensionality of microtechnology enables the fabrication of precise objects, like diffraction limited x-ray transmission optics. Based on deep x-ray/LIGA technology, first results are presented concerning the fabrication and modelling of parabolic and massive-serial focalizing x-ray transmission lenses in PMMA, as opposed to standard grazing incidence reflection optics. The theoretical performance limitations of such optical systems are derived and stem from fundamental physical properties like the anomalous dispersion properties of the used materials. Parabolic x-ray transmission lenses are limited to very small numerical apertures, but behave optically like any ideal transmission lens would do. The advantages of deep x-ray LIGA technology are its favorable surface roughness and inherent precision. Unlike silicon micromachining, LIGA technique profits from a larger choice of possible materials. The importance of low-Z compounds like Lithium or Be / B is pointed out together with necessary new techniques in the framework of LIGA, like electroplating from organic solutions.