Point-focusing monochromator crystal realized by hot plastic deformation of a Ge wafer

Pre-polished Ge(111) single-crystal wafers were deformed just below the melting temperature to prepare point-focusing Johansson monochromator crystals. The (111) lattice plane had curvature 2R in the focusing plane and R perpendicular to it, with a hemispherical inner surface with a radius of R = 600 mm. By using Cu Kalpha radiation, the diverging X-ray beam was focused onto a small spot.