X-ray refractive collimator based on planar silicon lens

We demonstrate that Si planar parabolic lens with long focus distance can collimate high energy X-rays with microradian precision. A divergent beam from a wiggler at the ESRF ID15 beamline is reduced from 15 microradian down to 1 microradian. We propose a new imaging technique for direct measurements of beam divergence. It is shown experimentally that precision better than 1 mrad may be really achieved. Measurements are done at the energy range 60 - 90 keV. Contribution of source size and diffraction phenomena to the precision and ultimate sensitivity of the developed technique is discussed.