European Synchrotron Radiation Facility (ESRF) in-house designed Kirkpatrick–Baez (KB) focusing systems have been extensively used for high efficiency beam focusing over the past years. More recently however, increasing interest in nanofocusing techniques has directed our development efforts towards more compact, higher stability designs for dynamic focusing systems in which the optimization of numerous parameters enables mirror bending approaching its mechanical limits. Simultaneously, progress in fixed focus mirror fabrication techniques – notably ion beam figuring, differential deposition and elastic emission machining – now make the fabrication of highly elliptical, fixed focus X-ray optics an interesting option. This has simplified conception (no bending mechanics) which in turn has led to the design of miniaturized KBs.

A general overview of these recent developments in both dynamic bending and fixed focus KB systems is presented.