Sagittal focusing of high-energy synchrotron X-rays with asymmetric Laue crystals. II. Experimental studies

The use of bent asymmetric Laue crystals to focus synchrotron X-rays sagitt ally from 15 to 50 keV is described. A four-bar bender, bending a rectangul ar planar crystal, produced the necessary sagittal and meridional bending f or this unique application. Adjustments of the tilt angle and height of the bent crystal resulted in first- and second-order corrections, respectively , to the dependence of the angle of diffraction on the horizontal position on the crystal. After these corrections, the remaining variation of the dif fraction angle was of the order of 10 mu rad. The theoretical sagittal foca l length was verified. A prototype of a double-crystal sagittally focusing monochromator was constructed and tested, using two identical Laue crystals . A horizontal divergence of 3 mrad was focused to a horizontal dimension o f about 0.4 mm. The X-ray flux density at the focus was a few hundred times larger than that of unfocused X-rays.