Nearly perfect large-area quartz: 4 meV resolution for 10 keV photons over 10 cm(2).

The perfection of two commercial top-grade quartz crystal wafers has been investigated using Bragg reflection at theta(B)=89.77 degrees of a 2.0 meV bandwidth beam of 9.979 keV X-rays by the (7\bar4\bar34) lattice planes. Topographic images show small defect concentrations (<or=5 cm(-2)). Energy scan widths are below 3 meV over 8 mm x 8 mm areas and 4 meV over the whole wafer ( approximately 11 cm(2)). This suggests that quartz can be a useful optical material.