Prisms deflect and disperse x-rays due to refraction very similarly to visible light. However, as the refractive index for X-rays is only very slightly different from unity and as it is even smaller than unity, the dispersion is found in the opposite direction compared to the visible range and it is observable only at very grazing incidence onto the refracting interface. Absorption will then limit the geometrical aperture of the prism to rather small dimensions. When the prism is further limited in length the aperture can be even smaller. In this case one will observe a small beam being refracted at the interface and as a result of this in the straight-through direction a small shadow. Both can easily be separated. It is proposed that this latter shadow can be used as a “negative” pinhole camera. Experimental data is presented for this application. It is discussed, that the quality of the refracting interface does not affect the shadow image and thus such device is well suited for the use at high power X-ray sources.

Date Published: 17 September 2014
PDF: 8 pages
Proc. SPIE 9210, X-Ray Free-Electron Lasers: Beam Diagnostics, Beamline Instrumentation, and Applications II, 92100L (17 September 2014); doi: 10.1117/12.2062567

Published in SPIE Proceedings Vol. 9210:
X-Ray Free-Electron Lasers: Beam Diagnostics, Beamline Instrumentation, and Applications II
Stefan P. Hau-Riege; Stefan P. Moeller; Makina Yabashi, Editor(s)