Small-offset Virtual Channel-cut Monochromator for Sub-micron X-ray Diffraction Beamline at Taiwan Photon Source

In this report, we illustrate the design concept of the small-offset(1mm) virtual channel-cut monochromator. The monochromator is specially designed for Sub-micron X-ray Diffraction Beamline at Taiwan Photon Source. It can offer a monochromatic beam with the resolving power better than 5000 in the range of 7 keV–25 keV and allows the beamline to cycle between the polychromatic and monochromatic modes with a fixed spot of 100 nm at the sample position. Its adjustments and the thermal deformation are reduced as possible to increase the stability of the focal point. The finite element analysis of the thermal deformation shows rather simple cooling techniques can be used. Base on above design, we expect the positional stability of the focus can be kept in around 10 nm.