The condenser-monochromator with dynamical aperture synthesis for the TXM at an undulator beamline at BESSY II

TLDR: The Gottingen transmission X-ray microscope at the low emittance electron storage ring BESSY II will use the concept of dynamical aperture synthesis for the condenser-monochromator.

Abstract: The Gottingen transmission X-ray microscope at the low emittance electron storage ring BESSY II will use the concept of dynamical aperture synthesis [1] for the condenser-monochromator. The concept is well suited as a condenser, as it can match the undulator U41 to the TXM objective and has many other advantages, too. It can use an off-axis transmission zone plate with comparatively wide zones of low aspect ratio, which therefore can be produced with almost theoretical efficiency. It will deliver a monochromaticity of 1000 to 3000. As the numerical aperture of any existing micro objective zone plate can be matched, the achievable resolution increases to the theoretical limit. Phase contrast imaging is possible with annular phase plates of extremely small width, a fast switching from amplitude contrast to phase contrast is possible. Stereo imaging with arbitrary stereo axis will be possible without tilting the object.