The measurement of the sagittal deviation of an X-ray beam diffracted on the inclined surface of an Si(111) single crystal was performed on beamline BM5 at the ESRF, with lambda = 0.1 nm and an inclination angle, beta, of 70 degrees . The measured value agrees with the theory developed in previous papers. The topographic picture of the longitudinal edge shows a structure that can be explained in terms of the properties of inclined diffraction.

Inclined double-crystal monochromators for synchrotron radiation suffer from aberration that is connected with the horizontal divergence of the synchrotron radiation beam. Two different methods are proposed to compensate for this aberration. The first method introduces slightly different angles of inclination for the first and the second monochromator crystals. The condition for the difference of the angles of inclination is Bragg angle dependent and also depends on the projection of the distance of both crystals onto the direction of the normal to the diffracting planes. The second method uses an additional inclined double-crystal monochromator cut such that the aberration introduced by the first pair of crystals is nearly completely compensated by the second pair of crystals. This method is independent of wavelength. Both methods are illustrated by ray tracing.

No abstract

The possibility of sagittally focusing synchrotron radiation using an asymmetric Laue crystal with profiled surfaces has been experimentally demonstrated for the first time. The sample was a Si single crystal with two parallel cylindrical holes of diameter 8 mm. The axes of the holes formed an angle of 7.95 degrees with the (111) diffracting planes and were arranged vertically with respect to the diffracting planes. 15.35 keV synchrotron radiation was diffracted in the space between the holes. The minimum thickness of this Laue crystal was 0.5 mm. The diffracted beam formed an angle of 0.55 degrees with the exit surface. The experiment was performed at beamline BM05 at the ESRF. The length of the beamline was not sufficiently long to detect the focus, but the experiment clearly showed that the diffracted beam was sagittally convergent.