Diffractive-refractive optics: low-aberration Bragg-case focusing by precise parabolic surfaces
| Authors | |
|---|---|
| Year of publication | 2010 |
| Type | Article in Periodical |
| Magazine / Source | Journal of Synchrotron Radiation |
| MU Faculty or unit | |
| Citation | |
| Web | http://www3.interscience.wiley.com/journal/123238603/abstract |
| Field | Solid matter physics and magnetism |
| Keywords | diffractive-refractive optics; aberration; parabolic groove; x-ray optics; x-ray diffraction |
| Description | Based on analytical formulae calculations and ray-tracing simulations a low-aberration focal spot with a high demagnification ratio was predicted for a diffractive-refractive crystal optics device with parabolic surfaces. Two Si(111) crystals with two precise parabolic-shaped grooves have been prepared and arranged in a dispersive position (+,-,-,+) with high asymmetry. Experimental testing of the device at beamline BM05 at the ESRF provided a focal spot size of 38.25 um at a focal distance of 1.4 m for 7.31 keV. This is the first experiment with a parabolic-shaped groove; all previous experiments were performed with circular grooves which introduced extreme aberration broadening of the focal spot. The calculated and simulated focal size was 10.8 um at a distance of 1.1 m at 7.31 keV. It is assumed that the difference between the measured and calculated/simulated focal spot size and focal distance is due to insufficient surface quality and to alignment imperfection. |
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